A large area multifilamentary plasma source

This paper discusses a large area multifilamentary plasma source used in the large volume plasma device. This source, based on directly heated filaments, is simple in design and produces quiescent (δn/n≈1%) plasmas of high density (⩽10¹⁸ m⁻³), low temperature (∼1–2 eV), over a large area (≈1.1 m²) and a large volume (≈1.6 m³). With the investment of ≈40 kW (1350 A, 30 V) power, the filaments are heated to ≈2000 K to yield emission current density ∼1 A cm⁻² at the filament surface. Experiments demonstrate that this source is suitable for carrying out electromagnetic wave excitation studies in the electron magnetohydrodynamics regime. There are certain inherent difficulties associated with direct heating which sets a maximum limit to the filament length and with the requirement of field tailoring. As far as the present study is concerned, these difficulties are acceptable in comparison with the distinct advantages the source possesses, in terms of its low cost and technical features, making it user-friendly.