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The 30th EPS Conference on Controlled Fusion and Plasma Physics took place in St Petersburg, Russian Federation, on 7th--11th July 2003. It was jointly organized by the Ioffe Physico-Technical Institute, the St Petersburg State Polytechnical University and Technical University Applied Physics Ltd, on behalf of the Plasma Physics Division of the European Physical Society (EPS). The members of the local organizing committee were drawn from these institutions:

B Kuteev, Chair, Polytechnical University

S Lebedev, Vice-Chair, Ioffe Institute

A Lebedev, Scientific Secretary, Ioffe Institute

V Bakharev, TUAP Ltd

V Grigor'yants, Ioffe Institute

V Sergeev, Polytechnical University

N Zhubr, Ioffe Institute

Over the years, the annual conference of the Plasma Physics Division of the European Physical Society has widened its scope. Contributions to the present conference covered widely diversified fields of plasma physics, ranging from magnetic and inertial fusion to low temperature plasmas. Plasma sizes under investigation ranged from tiny to astronomical. The topics covered during the conference were distributed over the following categories: tokamaks, stellarators, high intensity laser produced plasmas and inertial confinement, alternative magnetic confinement, plasma edge physics, plasma heating and current drive, diagnostics, basic plasma physics, astrophysical and geophysical plasmas and low temperature plasmas.

The scientific programme and paper selection were the responsibility of the Programme Committee appointed by the Board of the EPS Plasma Physics Division. The committee was composed of:

R Koch, Chairman, ERM/KMS Brussels, Belgium

E Ascasibar, CIEMAT Madrid, Spain

S Atzeni, Università di Roma, Italy

G Bonhomme, LPMI Nancy, France

C Chiuderi, Università di Firenze, Italy

B Kuteev, St Petersburg State Polytechnical,University, Russian Federation

M Mauel, Contact person APS-DPP, Columbia University New York, USA

R A Pitts, EPFL/CRPP Lausanne, Switzerland

R Salomaa, Helsinki University, Finland

B Sharkov, ITEP Moscow, Russian Federation

V Smirnov, Kurchatov Institute Moscow, Russian Federation

W Suttrop, IPP Garching, Germany

C Varandas, IST Lisbon, Portugal

F Wagner, Chair EPS-PPD, IPP Greifswald, Germany

H R Wilson, UKAEA Abingdon, UK

This committee selected 30 invited talks, in which the speakers were asked to address the general audience of plasma physicists and to exert their didactic skills. Out of the contributed papers, in total, 92 oral presentations were selected and distributed over parallel topical sessions. The other contributed papers (743) were presented as posters. The conference was attended by more than 700 participants from 41 countries. A major event during the conference was the award of the Hannes Alfv\'en Prize to Professor V E Fortov who gave a spectacular lecture on non-ideal plasmas. The associated paper is included in this special issue.

Following the tradition of this conference series, four-page summaries of the contributed papers are published as the Europhysics Conference Abstracts series, volume 27A. The publication is in the form of a CD-ROM sent free of charge to all participants and is also accessible via the website: http://www.ioffe.ru/EPS2003/.

This special issue of Plasma Physics and Controlled Fusion contains papers of the invited talks at this conference. These papers have been assessed according to the standards of the journal and examined by referees selected from or by the members of the International Programme Committee.

We are proud to provide, in this special issue, an overview of the forefront research in all major fields of plasma physics, through a set of papers accessible to the general audience of plasma physicists. The selection of this set of papers has been the work of the Programme Committee, and we would like to express our gratitude to all of its members for this successful selection. We are grateful to all authors for their efforts in providing high quality papers combining didactic introductions and accurate reports on recent developments in their field, a combination not always easy to realize. We would also like to thank all authors and referees for doing their work in due time, despite occasional short notice. Finally, we would also like to thank Plasma Physics and Controlled Fusion for the continuing support of this conference series.

The Hannes Alfvén Prize of the European Physical Society for Outstanding Contributions to Plasma Physics (2003) has been awarded to Vladimir Evgenievitch Fortov `for his seminal contributions in the area of non-ideal plasmas and strongly coupled Coulomb systems, and for his pioneering work on the generation and investigation of plasmas under extreme conditions'.

Vladimir Evgenievitch Fortov was born on 23 January 1946 in Noginsk, Russia. He studied physics at the Moscow Institute of Physics and Technology (PhD in 1976). In 1978 he was made a Professor and in 1991 he was awarded the Chair of the Moscow Institute of Physics and Technology. In the same year he became a Member of the Russian Academy of Sciences and was its vice-chairman from 1996 to 2001. From 1996 to 1998, Professor Fortov went into politics where he was just as successful, becoming Deputy Prime Minister of the Government of the Russian Federation and Minister of Science and Technology of the Russian Federation.

Professor Fortov has made outstanding experimental and theoretical contributions to low temperature plasma physics. His pioneering work investigating non-ideal plasmas produced by intense shock waves initiated a new research field---the physical properties of highly compressed plasmas with strong inter-particle interactions. Under the leadership of Professor Fortov, experimental methods for generating and diagnosing these plasmas under extreme conditions were developed. To generate intense shock waves, a broad spectrum of drivers was used---chemical explosives, hypervelocity impact, lasers, relativistic electrons, heavy-ion and soft x-ray beams. Measurements of the equation of state, transport and optical properties of strongly coupled plasmas were carried out, including the interesting region lying between condensed matter and rarefied plasmas where specific plasma phase transitions and insulator--metal transitions were expected and explored.

In another area of strongly coupled plasmas, Professor Fortov led theoretical and experimental studies on `dusty plasmas', carried out over a wide range of plasma parameters, using a broad spectrum of experimental techniques and devices. These studies embraced thermal combustion, glow and rf discharges and plasmas induced by cosmic ultraviolet and nuclear radiation. Under many of these conditions, ordered structures of dust in plasma liquids and plasma crystals were observed for the first time. Investigations of dusty plasmas induced by solar radiation and dust structures in DC glow discharges were first carried out on the Mir space station under micro-gravity conditions. The Russian--German experiment on dusty plasma crystals in space was successfully started on the International Space Station (ISS) in March 2001. This experiment was the first physics experiment on board the ISS.

On the basis of his experimental results, Professor Fortov developed a general method of constructing semi-empirical equations of state of highly compressed materials. He put forward theoretical models of thermodynamical, transport and optical properties of strongly non-ideal plasmas. On the basis of these models Professor Fortov developed two-dimensional and three-dimensional computer codes for computer simulations of the processes in advanced energetic, space, nuclear and aviation systems based on high energy density plasmas.

Professor Fortov has not only contributed to plasma theory but also to more applied topics. His laboratory participated in international space projects like the VEGA project (plasma dust impact phenomena), as well as the Halley Comet exploration, and studied plasma and shock wave phenomena stimulated by the impact of the Shoemaker-Levy 9 comet with Jupiter.

Professor Fortov is an internationally well known scientist. He collaborates actively with many plasma laboratories and institutions. He has received many national and international awards, including several USSR and Russian State Awards, the A P Karpinskii-Toepfer Scientific Award for Physics and Chemistry (1997), the P Bridgman Award for High Pressure Plasma Investigations and Achievements in High Pressure Physics and Chemistry (1999), the A Einstein Medal of UNESCO (2000) and the Max Planck Award for Physics (2002). It is therefore with great pleasure and honour that the Plasma Physics Division of the European Physical Society has awarded the Hannes Alfvén prize this year to Professor Vladimir Evgenievitch Fortov.

This article first appeared on the Europhyisics News website.

See the pdf for the full article.

The first burning fusion plasma experiment based on the tokamak principle, international tokamak experimental reactor (ITER) is now ready for construction. Based on the continuous progress of many years of fusion research, the design relies upon a large and robust set of experimental data. The focus of present day fusion research is therefore shifting towards the issues of ITER plasma operation and machine availability. The latter is governed mainly by plasma–wall interaction issues, in particular the lifetime of plasma-facing components and long-term tritium retention. To coordinate the research activities in this area a task force for plasma–wall interaction (EU-PWI-TF) has been initiated by the European fusion research programme under EFDA. This contribution describes the experimental database in these areas and outlines the task force strategy and further research that will be needed to address the critical issues.

The mechanisms for the explosive loss of plasma confinement that occurs in solar flares, magnetospheric sub-storms, tokamak disruptions and edge localized modes remain largely unexplained. Modelling the rapid onset of such events provides a considerable challenge to theory. A possible explanation for these events, nonlinear explosive ballooning, is discussed. In this mechanism a narrow finger of plasma erupts from inside the plasma growing explosively and pushing aside other field lines—the instability spreads from a small region until it disturbs lines across a large section of plasma. The model predicts the observed features of some high β tokamak disruptions.

The dynamics of a guided laser pulse propagation and wakefield generation in plasma channels, ionizing gases and gas filled capillaries is investigated. The efficient generation of a regular wakefield over long distances suitable for laser wakefield accelerators is demonstrated. The different schemes of electron bunch injection and compression to provide monoenergetic electron acceleration to high energies are analysed. A possibility of effective multistage acceleration of short electron bunches with low emittance and energy spread is demonstrated. The analytical results are confirmed by the results of numerical modelling.

When the aspect ratio of a tokamak (A = R/a) decreases significantly, there is a transformation of the well studied tokamak toroidal magnetic configuration into the spherical tokamak (ST) configuration. This configuration has high natural plasma elongation and triangularity and other unique equilibrium and stability properties of ST configuration, which are discussed in this paper.

European research into ST physics is well advanced in spite of the young age of this branch of fusion science. An overview of selected experimental and theoretical results obtained at Ioffe, Culham and Frascati is given with the emphasis on their complementarity and links to the main stream of tokamak research, such as ITER. An outline of the basic ST advantages and the potential of ST research for new insights into magnetic confinement is also given. More detailed descriptions of recent advances in ST theory and experiment may be found in the invited papers by Akers and Ono in the proceedings of this conference.

Tabletop Ti : sapphire lasers, such as the Jena multi-Terawatt laser, can nowadays reach focused intensities of up to 10²⁰ W cm⁻². The interaction of this intense light field with a solid target—in our case tantalum—leads to the production of energetic bremsstrahlung x-rays. These are used to induce (γ,n)- and (γ,f)-reactions in ¹⁸¹Ta, ¹²⁹I, ²³²Th, ²³⁸U and ⁹Be. The results are discussed in the context of laser plasma diagnostics and photo transmutation studies on radioactive material.

We also report on fusion experiments in low-Z targets where the fusion neutrons are utilized to characterize ion acceleration processes.

Recent progress in experimental and theoretical studies of edge localized mode (ELM) physics is reviewed for the reactor relevant plasma regimes, namely the high confinement regimes, that is, H-modes and advanced scenarios.

Theoretical approaches to ELM physics, from a linear ideal magnetohydrodynamic (MHD) stability analysis to non-linear transport models with ELMs are discussed with respect to experimental observations, in particular the fast collapse of pedestal pressure profiles, magnetic measurements and scrape-off layer transport during ELMs.

High confinement regimes with different types of ELMs are addressed in this paper in the context of development of operational scenarios for ITER. The key parameters that have been identified at present to reduce the energy losses in Type I ELMs are operation at high density, high edge magnetic shear and high triangularity. However, according to the present experimental scaling for the energy losses in Type I ELMs, the extrapolation of such regimes for ITER leads to unacceptably large heat loads on the divertor target plates exceeding the material limits. High confinement H-mode scenarios at high triangularity and high density with small ELMs (Type II), mixed regimes (Type II and Type I) and combined advanced regimes at high β_p are discussed for present-day tokamaks. The optimum combination of high confinement and small MHD activity at the edge in Type II ELM scenarios is of interest to ITER. However, to date, these regimes have been achieved in a rather narrow operational window and far from ITER parameters in terms of collisionality, edge safety factor and β_p.

The compatibility of the alternative internal transport barrier (ITB) scenario with edge pedestal formation and ELMs is also addressed. Edge physics issues related to the possible combination of small benign ELMs (Type III, Type II ELMs, quiescent double barrier) and high performance ITBs are discussed for present-day experiments (JET, JT-60U, DIII-D) in terms of their relevance for ITER. Successful plasma edge control, at high triangularity (∼0.5) and high density (∼0.7n_GR), in ITB scenarios in JET is reported.

Active control of ELMs by edge current, pellet injection, impurities and external magnetic perturbations creating an ergodic zone localized at the separatrix are discussed for present-day experiments and from the perspective of future reactors.

The wave–particle interaction is central to microscopic plasma dynamics. A paradigm of such an interaction is one occurring during the weak warm beam–plasma instability: a Langmuir turbulence sets in and saturates by the formation of a plateau in the particle distribution function. A new approach permits us to deal with the regular and chaotic aspects of this problem using the classical mechanics of the corresponding N-body problem only. The classical Landau-van Kampen theory is recovered by using mathematical tools not more intricate than a finite Fourier sum. A single calculation yields spontaneous emission and the particle dynamics as well; classical explicative models of Landau damping are found to be misleading. Recent tools of Hamiltonian chaos enable us to derive the quasilinear equations in the regime of saturation of the instability. The calculations are readable by graduate students and provide a simple solution to a 20 year old controversy in the Vlasovian frame. As a result, the macroscopic irreversible evolution of a plasma is described by fully accounting for its microscopic reversible mechanics; for the first time, an old dream of the 19th century comes true: the irreversible evolution of an N-body problem is described by taking into account the true character of its chaotic motion.

An overview of recent progress in the theory of inertial confinement fusion (ICF) targets is presented. Work on traditional target schemes, based on the hydrodynamic mode of ignition, is reviewed only briefly, while most of the attention is devoted to the fast ignition approach. The general advantages of fast ignition are illustrated with a simple model for characteristic assembled fuel configurations. Special attention is paid to a newly proposed concept of a cylindrical reactor-size target, compressed and ignited (in the fast ignition mode) by two separate beams of very energetic (E_i ⪆ 0.5 GeV u⁻¹) heavy ions.

The extraordinary wave at the second harmonic of the electron cyclotron frequency produces and heats the plasma in the helically symmetric experiment. Ray-tracing calculations predict 40% first pass absorption at a plasma density of 1.5 × 10¹⁸ m⁻³ and an electron temperature of 400 eV. To measure the wave absorption, a set of absolutely calibrated microwave detectors is installed along the machine. It was found that the absorption efficiency is very high (about 0.9) in the quasi-helically symmetric (QHS) and mirror configurations, and it drops to 0.6 in the anti-mirror mode. The confinement of particles in the different configurations is studied in the neutral gas breakdown experiments. With the same gas pressure and heating power, the density for the QHS configuration has a larger growth rate (10⁴ s⁻¹) compared with the mirror (5 × 10³ s⁻¹) and anti-mirror modes (2 × 10³ s⁻¹). A study of the stored energy versus launched power and plasma density shows that it increases linearly (up to 50 J) with power and has a maximum at a low plasma density (at about 0.4 × 10¹⁸ m⁻³). The central electron temperature measured by Thomson scattering also rises linearly with heating power and reaches 600 eV at 100 kW of launched power.

High power gyrotron oscillators are mainly used as millimetre wave sources for electron cyclotron resonance heating (ECRH), electron cyclotron current drive (ECCD), stability control and diagnostics of magnetically confined plasmas for energy generation by controlled thermonuclear fusion. The maximum pulse length of commercially available 1.0 MW gyrotrons, employing open-ended cylindrical resonators and chemical vapour deposition diamond output windows is 12 s at 140 GHz and 9 s at 170 GHz, with efficiencies slightly above 30%. The energy world record of 160 MJ at a power level around 0.9 MW is held by the European FZK-CRPP-CEA-TED collaboration. Total efficiencies of up to 50% have been obtained using a single-stage depressed collector (SDC). To achieve output powers of around 2 MW in continous wave operation at the ITER reference frequency 170 GHz, it is necessary to use a coaxial cavity geometry. A maximum output power of 2.2 MW at 165 GHz was obtained at FZK with an efficiency of 28% (48% in SDC operation). The availability of gyrotrons with fast frequency tunability would permit the use of a simple, fixed, non-steerable mirror antenna for local current drive experiments on ITER. This work reports on the progress in gyrotron development and the status of advanced coaxial cavity gyrotrons and step-wise frequency tunable gyrotrons.

A review of magnetohydrodynamic limits to tokamak operation in terms of current, density and pressure is given. Although the current and density limits in a tokamak usually lead to disruptive termination of the discharge, it is argued that these can be avoided by staying away from the respective limits. This is especially true since operation close to these limits is not really desirable, due to the decreased confinement at very high density and the high disruptivity at low q. On the other hand, the limit to plasma pressure set by neoclassical tearing modes (NTMs) and resistive wall modes (RWMs) is too low to guarantee economic operation of future fusion reactors. Therefore, active control of these two instabilities is now being studied. Noticeable progress has been made by NTM stabilization with ECCD. Avoidance of NTMs and RWMs by tailoring sawteeth and spinning the plasma, shows promising results. Also, experiments on direct RWM stabilization by active coils are showing their first encouraging results.

A combination of recently installed state-of-the-art imaging and profile diagnostics, together with established plasma simulation codes, are providing for the first time on Mega Ampère Spherical Tokamak (MAST) the tools required for studying confinement and transport, from the core through to the plasma edge and scrape-off-layer (SOL). The H-mode edge transport barrier is now routinely turned on and off using a combination of poloidally localized fuelling and fine balancing of the X-points. Theory, supported by experiment, indicates that the edge radial electric field and toroidal flow velocity (thought to play an important role in H-mode access) are largest if gas fuelling is concentrated at the inboard side. H-mode plasmas show predominantly type III ELM characteristics, with confinement H_H factor (w.r.t. scaling law IPB98[y, 2]) around ∼1.0. Combining MAST H-mode data with the International Tokamak Physics Activities (ITPA) analyses, results in an L–H power threshold scaling proportional to plasma surface area (rather than P_LH ∼ R²). In addition, MAST favours an inverse aspect ratio scaling P_LH ∼ ε^0.5. Similarly, the introduction of type III ELMing H-mode data to the pedestal energy regression analysis introduces a scaling W_ped ∼ ε^−2.13 and modifies the exponents on R, B_T and κ. Preliminary TRANSP simulations indicate that ion and electron thermal diffusivities in ELMing H-mode approach the ion-neoclassical level in the half-radius region of the plasma with momentum diffusivity a few times lower. Linear flux-tube ITG and ETG microstability calculations using GS2 offer explanations for the near-neoclassical ion diffusivity and significantly anomalous electron diffusivity seen on MAST. To complement the baseline quasi-steady-state H-mode, newly developed advanced regimes are being explored. In particular, 'broad' internal transport barriers (ITBs) have been formed using techniques developed at conventional aspect ratio. Electron and ion energy diffusivities are reduced towards the ion-neoclassical level in the ITB region of both co- and counter-injection NBI heated plasmas, with momentum diffusivity up to 10 times lower. Moving out to the edge and SOL, OSM2/EIRENE modelling is being used to extract edge perpendicular particle and heat diffusivities, results being consistent with the ballooning nature of power-flow seen in L-mode and reduction in outboard turbulence seen in ELM-free and inter-ELM H-mode. Modelling of parallel SOL transport requires the inclusion of the mirror force (∼10 times higher in MAST than at the conventional aspect ratio) and B2SOLPS5.0 simulations show the edge electric field to be well modelled by neoclassical theory. Transient edge transport phenomena are being studied in detail using a variety of techniques (e.g. probability density function (PDF) and power spectrum analysis, differencing and rescaling methods). Intermittent transport is associated with a radial efflux at up to a tenth of the sound speed and up to 30 cm from the separatrix. Arguably, the most dramatic edge events seen in the plasma periphery are the ELMs. Recent results using fast, high-resolution visible imaging confirm the hypothesis that ELMs have both poloidal and toroidal structures (n ∼ 10 at q = 4), consistent with recent theories of the non-linear evolution of ballooning modes.

Magnetohydrodynamic (MHD) turbulence plays a major role in the dynamics and thermodynamics of astrophysical plasmas in many environments and over a wide range of scales and parameters: primary examples are the heating of stellar and accretion disk coronae, acceleration of stellar winds, and star formation in molecular clouds. In the case of the solar wind and corona in situ measurements and remote-sensing observations have given the most detailed experimental knowledge of the interplay between large-scale driving forces, the development of a turbulent cascade, and the collisionless kinetics of dissipation, than in any other natural magnetized plasma environment (with the possible exception of the earth's magnetosphere). The questions of coronal and solar wind acceleration will be reviewed here within the general context of MHD turbulence and nonlinear interactions, from the large-scale energy sources and driving to the dissipation scales dominated by wave–particle interactions, from the special role of Alfvén waves to the naturally intermittent nature of coronal energy release and solar flares.

There has been rapid progress in inertial fusion in the past few years. This progress spans the construction of ignition facilities, a wide range of target concepts and the pursuit of integrated programmes to develop fusion energy using lasers, ion beams and z-pinches.

Two ignition facilities are under construction, the national ignition facility (NIF) in the United States and the laser megajoule (LMJ) in France, and both projects are progressing towards an initial experimental capability. The laser integration line prototype beamline for LMJ and the first four beams of NIF will be available for experiments in 2003. The full 192 beam capability of NIF will be available in 2009 and ignition experiments are expected to begin shortly after that time.

There is steady progress in target science and target fabrication in preparation for indirect-drive ignition experiments on NIF. Advanced target designs may lead to 5–10 times more yield than initial target designs. There has also been excellent progress on the science of ion beam and z-pinch-driven indirect-drive targets.

Excellent progress on direct-drive targets has been obtained on the Omega laser at the University of Rochester. This includes improved performance of targets with a pulse shape predicted to result in reduced hydrodynamic instability. Rochester has also obtained encouraging results from initial cryogenic implosions.

There is widespread interest in the science of fast ignition because of its potential for achieving higher target gain with lower driver energy and relaxed target fabrication requirements. Researchers from Osaka have achieved outstanding implosion and heating results from the Gekko XII Petawatt facility and implosions suitable for fast ignition have been tested on the Omega laser.

A broad-based programme to develop lasers and ion beams for inertial fusion energy (IFE) is under way with excellent progress in drivers, chambers, target fabrication and target injection. KrF and diode pumped solid-state lasers are being developed in conjunction with dry-wall chambers and direct-drive targets. Induction accelerators for heavy ions are being developed in conjunction with thick-liquid protected wall chambers and indirect-drive targets.

ITER will be the first magnetic confinement device with burning DT plasma and fusion power of about 0.5 GW. Parameters of ITER plasma have been predicted using methodologies summarized in the ITER Physics Basis (1999 Nucl. Fusion39 2175). During the past few years, new results have been obtained that substantiate confidence in achieving Q ⩾ 10 in ITER with inductive H-mode operation. These include achievement of a good H-mode confinement near the Greenwald density at high triangularity of the plasma cross section; improvements in theory-based confinement projections for the core plasma, even though further studies are needed for understanding the transport near the plasma edge; improvement in helium ash removal due to the elastic collisions of He atoms with D/T ions in the divertor predicted by modelling; demonstration of feedback control of neoclassical tearing modes and resultant improvement in the achievable β-values; better understanding of edge localized mode (ELM) physics and development of ELM mitigation techniques; and demonstration of mitigation of plasma disruptions. ITER will have a flexibility to operate also in steady-state and intermediate (hybrid) regimes. The 'advanced tokamak' regimes with weak or negative central magnetic shear and internal transport barriers are considered as potential scenarios for steady-state operation. The paper concentrates on inductively driven plasma performance and discusses requirements for steady-state operation in ITER.

The theory of resistive wall modes (RWMs) is discussed and compared with experimental results. Special attention is given to the possibilities of stabilizing the RWM by plasma rotation and active feedback. A simple cylindrical model is used to illustrate various aspects of active control. Fully toroidal computations are also presented, including predictions for RWM stabilization in ITER. According to ideal MHD, robust control of RWM should be straightforward. Theory for stabilization by rotation is discussed, and a semikinetic model is introduced, which compares favourably with experiment. The semikinetic model produces somewhat lower rotation thresholds than previous models.

Detailed disruption related studies have been undertaken at JET in 2001–2003 and are compared and contrasted with results from other tokamaks. An enhanced halo current detection system has allowed more precise asymmetry measurements to be made, confirming the assumptions in the ITER design guidelines. The runaway electron database has been systematically analysed and self-consistent simulations are underway. Disruption heat deposition, which is of fundamental importance for ITER, has been investigated in JET. It has been found that normally only a small fraction of the thermal energy goes to the divertor and that during the thermal quench some energy goes to the outer wall. The neutral point has been experimentally found and a plasma control model has been used to reproduce the dedicated discharges. Helium, neon and argon puffs have been applied as disruption mitigation techniques in JET following the success of recent studies in ASDEX Upgrade, TEXTOR and DIII-D.

A major objective of the experimental program in the last phase of the W7-AS stellarator was to explore and demonstrate the high-β performance of advanced stellarators. MHD-quiescent discharges at low impurity radiation levels with volume averaged β-values of up to ⟨β⟩ = 3.4% have been achieved. A very important prerequisite was the attainment of the high density H-Mode (HDH) regime. This was made possible by the installation of extensive graphite plasma facing components designed for island divertor operation. The co-directed neutral beam injection provided increased absorbed heating power of up to 3.2 MW in high-β plasmas with B ⩽ 1.25 T. The anticipated improved features concerning equilibrium and stability at high plasma β could be verified experimentally by the comparison of x-ray data with free boundary equilibrium calculations. The maximum β found in configurations with a rotational transform around is determined by the available heating power. No evidence of a stability limit has been found in the accessible configuration space, and the discharges are remarkably quiescent at maximum β, most likely due the increase of the magnetic well depth. An increase in low m/n MHD activity is typically observed during the transition towards high β. The beneficial stability properties of net-current-free configurations could be demonstrated by comparison with configurations where a significant inductive current drive was involved. Current driven instabilities such as tearing modes and soft disruptions can prevent access to β-values as high as in the currentless case. The experimental results indicate that optimized stellarators such as W7-X can be considered as a viable option for an attractive stellarator fusion reactor.

In nearly collisionless astrophysical plasmas and magnetic fusion experiments it is of interest to understand the possibilities of fast magnetic reconnection processes. Fluid modelling of collisionless magnetic reconnection in the presence of a strong magnetic guide field has demonstrated high reconnection rates where electron inertia and electron compressibility play an important role. Numerical simulations show that the high reconnection rate involves the acceleration of electrons in an exceedingly thin current layer. However, in this fluid model of reconnection, smaller and smaller length scales develop in the current density and vorticity distributions. More appropriate for a collisionless plasma is a kinetic model. Beside the fact that kinetic effects offer additional reconnection mechanisms, kinetic effects also modify the reconnection process due to electron inertia. Kinetic effects such as thermal broadening resolve the singularities that arise in fluid models while allowing for a fast reconnection rate. In addition, kinetic theory offers an interpretation of the current structures that form in terms of a resonance with thermal electrons. Another point of interest is that reconnection in a magnetically confined plasma can bring together field lines with a temperature or density difference. A kinetic description resolves the steep gradients that would arise in a collisionless fluid model. This paper analyses these issues on the basis of stationary reconnection processes. Stationarity rules out the additional kinetic effects of wave–particle interactions such as Landau resonances.

Inertial confinement fusion capsule implosions absorbing up to 35 kJ of x-rays from a ∼220 eV dynamic hohlraum on the Z accelerator at Sandia National Laboratories have produced thermonuclear D–D neutron yields of (2.6±1.3) × 10¹⁰. Argon spectra confirm a hot fuel with T_e ∼ 1 keV and n_e ∼ (1–2) × 10²³ cm⁻³. Higher performance implosions will require radiation symmetry control improvements. Capsule implosions in a ∼70 eV double-Z-pinch-driven secondary hohlraum have been radiographed by 6.7 keV x-rays produced by the Z-beamlet laser (ZBL), demonstrating a drive symmetry of about 3% and control of P₂ radiation asymmetries to ±2%. Hemispherical capsule implosions have also been radiographed in Z in preparation for future experiments in fast ignition physics. Z-pinch-driven inertial fusion energy concepts are being developed. The refurbished Z machine (ZR) will begin providing scaling information on capsule and Z-pinch in 2006. The addition of a short pulse capability to ZBL will enable research into fast ignition physics in the combination of ZR and ZBL-petawatt. ZR could provide a test bed to study NIF-relevant double-shell ignition concepts using dynamic hohlraums and advanced symmetry control techniques in the double-pinch hohlraum backlit by ZBL.

Research on the spherical torus (or spherical tokamak) (ST) is being pursued to explore the scientific benefits of modifying the field line structure from that in more moderate aspect ratio devices, such as the conventional tokamak. The ST experiments are being conducted in various US research facilities including the MA-class National Spherical Torus Experiment (NSTX) at Princeton, and three medium sized ST research facilities: PEGASUS at University of Wisconsin, HIT-II at University of Washington, and CDX-U at Princeton. In the context of the fusion energy development path being formulated in the US, an ST-based Component Test Facility (CTF) and, ultimately a Demo device, are being discussed. For these, it is essential to develop high performance, steady-state operational scenarios. The relevant scientific issues are energy confinement, MHD stability at high beta (β), non-inductive sustainment, Ohmic-solenoid-free start-up, and power and particle handling. In the confinement area, the NSTX experiments have shown that the confinement can be up to 50% better than the ITER-98-pby2 H-mode scaling, consistent with the requirements for an ST-based CTF and Demo. In NSTX, CTF-relevant average toroidal beta values β_T of up to 35% with a near unity central β_T have been obtained. NSTX will be exploring advanced regimes where β_T up to 40% can be sustained through active stabilization of resistive wall modes. To date, the most successful technique for non-inductive sustainment in NSTX is the high beta poloidal regime, where discharges with a high non-inductive fraction (∼60% bootstrap current+NBI current drive) were sustained over the resistive skin time. Research on radio-frequency (RF) based heating and current drive utilizing high harmonic fast wave and electron Bernstein wave is also pursued on NSTX, PEGASUS, and CDX-U. For non-inductive start-up, the coaxial helicity injection, developed in HIT/HIT-II, has been adopted on NSTX to test the method up to I_p ∼ 500 kA. In parallel, start-up using a RF current drive and only external poloidal field coils are being developed on NSTX. The area of power and particle handling is expected to be challenging because of the higher power density expected in the ST relative to that in conventional aspect-ratio tokamaks. Due to its promise for power and particle handling, liquid lithium is being studied in CDX-U as a potential plasma-facing surface for a fusion reactor.

This paper presents experimental results on the accessibility and the properties of plasmas with improved confinement in TCV. First, the H-mode threshold power is measured in Ohmic plasmas. Above an Ohmic threshold density, the threshold power increases with the density. A lower threshold density is found when additional electron cyclotron heating (ECH) is applied. At these low densities, the threshold power increases dramatically with decreasing density. Only a small fraction of the wide operational domain leading to the Ohmic H-mode is found to lead to a stationary regime with edge localized modes (ELMs). The ELMs have an irregular frequency, but in TCV they can be triggered by an external magnetic perturbation that induces a rapid vertical movement of the plasma. With this perturbation, the ELM frequency can be increased. The ELM triggering mechanism is provided by the vertical movement of the plasma away from the X-point of a single null configuration. This movement induces a positive current at the plasma edge, and we deduce that the ELMs are being controlled by this modification of the plasma edge current.

Electron internal transport barriers (eITBs) are produced deep in the plasma during the stationary phase of TCV discharges. Different scenarios of ECH or electron cyclotron current drive (ECCD) at different radial locations have been used to obtain eITBs with and without inductively driven current. The eITBs are characterized by steep electron temperature gradients, high confinement improvement and a large fraction of bootstrap current. In plasmas with fully non-inductively driven current the size and the strength of the eITB are controlled by the location of the power deposition and by the co- or counter-direction of the central ECCD. Finally, a small inductive perturbation of an otherwise non-inductively driven plasma current profile progressively shrinks the eITB, confirming the link between current profiles and eITBs.

The recent development of real-time measurements and control tools in JET has enhanced the reliability and reproducibility of the relevant ITER scenarios. Diagnostics such as charge exchange, interfero-polarimetry, electron cyclotron emission have been upgraded for real-time measurements. In addition, real-time processes like magnetic equilibrium and q profile reconstruction have been developed and applied successfully in real-time q profile control experiments using model based control techniques. Plasma operation and control against magnetohydrodynamic instabilities are also benefiting from these new systems. The experience gained at JET in the field of real-time measurement and control experiments operation constitutes a very useful basis for the future operation of ITER scenarios.

The basic scales of motion and computational requirements for low frequency fluid drift turbulence are summarized in tutorial fashion. Basic signatures for each of the competing eigenmode types are given, some of which are accessible experimentally. The emphasis is on edge turbulence since it is less intuitive. The difference in physical mechanism between linear instabilities and fully developed turbulence at the same parameters is shown. The difference in physical character from more familiar MHD models is also addressed. Experimentally, one needs to measure the fluctuating potential as well as the transported quantities in order to distinguish among physical mechanisms.

In this paper, recent advances in the physics of low pressure inductively coupled plasmas (ICPs) are reviewed where the interaction of an electromagnetic field with electrons is governed by electron thermal motion rather than electron–atom collisions. Direct measurement of the rf electric field and rf current density in the plasma made it possible to distinguish between collisional and stochastic (collisionless) electron heating. Several new phenomena such as a wave phase bifurcation, phase velocity reversal, a second current layer and negative power absorption have been found and interpreted in terms of non-local electrodynamics. Nonlinear effects induced by the rf Lorentz force such as nonlinear plasma polarization and second harmonic currents, as well as modification of the spatial distribution of the plasma caused by ponderomotive forces have been demonstrated in ICP under discharge conditions typical for industrial applications.

Standard diagnostics for fundamental plasma parameters and for plasma physics are routinely utilized for daily operation and physics studies in the large helical device (LHD) with high reliability. Diagnostics for steady-state plasma are under intensive development, especially for T_e, n_e (yttrium–aluminium garnet (YAG) laser Thomson, CO₂ laser polarimeter), data acquisition in steady-state and heat-resistant probes. To clarify the plasma properties of the helical structure, two- or three-dimensional diagnostics are being aggressively developed: tangential cameras (fast SX TV, photon counting CCD, H_α TV); tomography (tangential SX CCD, bolometer); imaging (bolometer, ECE, reflectometer). Divertor and edge physics are important key issues for steady-state operation. Diagnostics for neutral flux (H_α array, Zeeman spectroscopy) and n_e (fast scanning probe, Li beam probe, pulsed radar reflectometer) are also in advanced stages of development. In addition to these, advanced diagnostics are being intensively developed in LHD through domestic and international collaborations.

Interaction of waves in the ion cyclotron range of frequencies (ICRF) with a plasma has a number of key properties that make them attractive beyond pure heating. First, the waves can interact resonantly with either the plasma ions or electrons. In the case of ion cyclotron damping, a small number of resonant ions are often accelerated to high energies. These ions, apart from heating the bulk plasma via Coulomb collisions, can increase fusion reactivity, affect plasma stability and drive current. They have also been invaluable in diagnostic applications and simulations of fusion-born 3.5 MeV alpha-particles. The second key property of ICRF waves is the transfer of wave momentum to the plasma. This allows one to drive current, affect plasma rotation and induce radial transport of the fast-ions with toroidally directed waves. Finally, ICRF power deposition is rather narrow and its location can be externally controlled, which has important applications in improving the plasma performance, affecting the local plasma transport and providing a tool for plasma transport studies. Representative examples from present-day tokamak experiments are reviewed to highlight the available capabilities.

For several reasons, improved-confinement achieved in the reversed field pinch (RFP) during the last few years can be characterized as 'tokamak-like'. Historically, RFP plasmas have had relatively poor confinement due to tearing instability which causes magnetic stochasticity and enhanced transport. Tearing reduction is achieved through modification of the inductive current drive, which dramatically improves confinement. The electron temperature increases to >1 keV and the electron heat diffusivity decreases to ∼5 m² s⁻¹, comparable with the transport level expected in a tokamak plasma of the same size and current. This corresponds to a 10-fold increase in global energy confinement. Runaway electrons are confined, and Fokker–Planck modelling of the electron distribution reveals that the diffusion at high energy is independent of the parallel velocity, uncharacteristic of stochastic transport. Improved-confinement occurs simultaneously with increased beta ∼15%, while maintaining a magnetic field strength ten times weaker than a comparable tokamak. Measurements of the current, magnetic, and electric field profiles show that a simple Ohm's Law applies to this RFP sustained without dynamo relaxation.

Since 30 years already, the All-Russia Institute of Experimental Physics (VNIIEF) is engaged in investigations on the problem of inertial confinement fusion. The high-power laser facilities 'Iskra 5' (Kirillov G A et al 1990 Laser Particle Beams8 827–31) and 'Luch' (Sukharev S A 3rd Int. Conf. on Solid State Lasers for Application to Inertial Confinement Fusion ed W H Lowdermilk Proc. SPIE3492 12–24) were created and are operating now in the framework of this programme. The main lines of the work at these facilities are the investigation of the physics of thermonuclear targets and the development of laser technologies. This work resulted in the development of a project of the new generation facility 'Iskra-6'.

This report presents the main results of these works carried out at Russian Federal Nuclear Center—VNIIEF in the period 1991–2002.

Zonal flows, thought crucial to the saturation and self-regulation of turbulence and turbulent transport in magnetically confined plasmas, have been observed and characterized in the edge region of DIII-D plasmas. These flows exhibit temperature scaling characteristics and spatial features predicted for geodesic acoustic modes (GAMs), a class of higher-frequency zonal flows seen in nonlinear simulations of plasma turbulence. The zonal flows (GAMs) have been observed in the turbulence flow-field in the radial region 0.85 ⩽ r/a ⩽ 1.0 via application of time-delay-estimation techniques to two-dimensional measurements of density fluctuations, obtained with beam emission spectroscopy. Spatial and temporal analysis of the resulting flow-field demonstrates the existence of a coherent oscillation (approximately 15 kHz) in the poloidal flow of density fluctuations that has a long poloidal wavelength, possibly m = 0, narrow radial extent (k_rρ_i < 0.2), and a frequency that varies monotonically with the local temperature. The approximate effective shearing rate, dv_θ/d r, of the flow is of the same order of magnitude as the measured nonlinear decorrelation rate of the turbulence. These characteristics are consistent with predicted features of zonal flows, specifically identified as GAMs, observed in three-dimensional Braginskii simulations of core/edge turbulence.