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Investigation of highly complex electromagnetic phenomena responsible for fundamental processes in geospace plasma calls for a laboratory device, large enough to provide minimum boundary effects on the electromagnetic waves under concern. The production of large volume, uniform, and quiescent plasma of density ∼1012 cm−3 requires a suitable large area plasma source. The influence of energetic electrons on the phenomena under study can be eliminated using pulsed, highly reproducible discharges so that the afterglow, devoid of energetic electrons, becomes the experimental plasma. Measurement over a large volume with high spatial and temporal resolution, acquisition, and storage of voluminous data form other difficult tasks. The requirement to have tasks of plasma generation, wave excitation, and data acquisition automatically sequenced, also demands a sophisticated control system. A large volume plasma device (LVPD), possessing the following unique features, has been developed in our laboratory: (i) a large area multifilamentary source, (ii) a pulsed power system (width ⩽15 ms and turn off time ≈10 μs), (iii) a three-axes probe drive, (iv) data acquisition and control system with 1 GS/s sampling rate and ≈20 GB memory, and (v) an extended magnet coil system giving desired field profile. The achieved plasma parameters include, ne∼1012 cm−3, Te≈8 eV in the main glow, and ne≈3×1011 cm−3 and Te≈2 eV in the after glow, and plasma uniformity within 5% over 1 m in axial and radial extents. The present article describes the LVPD device.

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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 ( 10 18 m −3 ), low temperature (∼1-2 eV), over a large area (≈1.1 m 2 ) and a large volume (≈1.6 m 3 ). 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.

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This paper discusses laboratory production of an extremely large-beta (β∼103) plasma, termed ELB plasma, over an extended volume of 0.5m3. The plasma β can be varied from <1 to values as large as 103, thereby allowing us to study physical processes through a large range of β. Desired β values are achieved by tailoring the ambient magnetic field by compensating fields over time scales far less than the plasma confinement time. We observe that during this compensation, the magnetic field penetration from the wall to the plasma occurs at Whistler speed. The Whistler mode is accompanied by excitation of electrostatic ion wave. We have shown that the diamagnetism of the ELB plasma is considerably modified essentially through the effect of finiteness of electron Larmor radius (rLe) in the force equilibrium. Application of these results to the space plasma is pointed out.

This article describes hardware and software solutions to a need which is comprised of (i) acquisition of a large volume of high speed data with multiple time scales, (ii) control of various operational parameters of device and diagnostics, and (iii) processing and management of the acquired data for a large volume plasma device. The solution relies on the base of a VXI bus and uses a standard PC with a Windows 98/NT operating system and C as the programming language. The system is networked with the existing network with the result of allowing a large data storage space of processing facilities from any terminal in the laboratory.

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