We report the observation of electron-temperature-gradient (ETG) driven turbulence in laboratory plasma a large volume device. The removal unutilized primary ionizing and nonthermal electrons from uniform density imposition control gradient electron temperature ($\ensuremath{\nabla}{T}_{e}$) are all achieved by placing (2 m diameter) magnetic energy filter middle In dressed plasma, observed ETG lower hybrid range frequencies $\ensuremath{\nu}=(1--80\text{ }\text{ }\mathrm{kHz})$ is...

Investigation of highly complex electromagnetic phenomena responsible for fundamental processes in geospace plasma calls a laboratory device, large enough to provide minimum boundary effects on the waves under concern. The production volume, uniform, and quiescent density ∼1012 cm−3 requires suitable area source. influence energetic electrons study can be eliminated using pulsed, reproducible discharges so that afterglow, devoid electrons, becomes experimental plasma. Measurement over volume...

This paper describes an in-house designed large Electron Energy Filter (EEF) utilized in the Large Volume Plasma Device (LVPD) [S. K. Mattoo, V. P. Anita, L. M. Awasthi, and G. Ravi, Rev. Sci. Instrum. 72, 3864 (2001)] to secure objectives of (a) removing presence remnant primary ionizing energetic electrons non-thermal electrons, (b) introducing a radial gradient plasma electron temperature without greatly affecting profile density, (c) providing control on scale length temperature. A set...

This paper presents a theory of coupled whistler (W) and electron temperature gradient (ETG) mode using two-fluid model in high beta plasma. Non-adiabatic ion response, parallel magnetic field perturbation (δBz), perpendicular flutter (δB⊥), collisions are included the treatment theory. A linear dispersion relation for whistler-electron (W-ETG) is derived. The numerical results obtained from this compared with experimental observed large volume plasma device (LVPD) [Awasthi et al., Phys....

Observation of electromagnetic fluctuations in lower hybrid range frequencies is reported a large volume linear plasma device. The instability observed the core when narrow multifilamentary source used and it absent broad used. This high beta characterized by broadband turbulent spectra with central frequency ω=5×104 s−1 wave number k⊥=0.2 cm−1 satisfies condition k⊥ρe≤1, where ρe electron Larmor radius. When increasing axial magnetic field reduces beta, weakens magnitude component totally...

This paper presents the first controlled observations on electron temperature gradient (ETG) driven turbulence in finite beta (β ∼ 0.6) plasmas of Large Volume Plasma Device (LVPD). The observed instability is investigated core region target plasma when a ∼2 m diameter magnetic energy filter used. lower hybrid range frequencies has electromagnetic fluctuations associated with it and characterized by broadband spectra central frequency, ν ⩽ 10 kHz, wave number, k⊥ = (0.1–0.2) cm−1, which...

An electron energy filter (EEF) is embedded in the Large Volume Plasma Device plasma for carrying out studies on excitation of turbulence by a gradient temperature (ETG) described paper Mattoo et al. [S. K. al., Phys. Rev. Lett. 108, 255007 (2012)]. In this paper, we report results response to EEF. It shown that inhomogeneity magnetic field EEF switches several physical phenomena resulting regions with different characteristics, including region free from energetic electrons, suitable study...

The measurement of electron temperature in plasma by Langmuir probes, using ramped bias voltage, is seriously affected the capacitive current capacitance cable between probe tip and data acquisition system. In earlier works a dummy was used to balance currents. Under these conditions, measured kept less than few mA. Such probes are suitable for measurements where ion saturation order hundreds This paper reports that controlled balancing can be minimized 20 μA, allowing done with μA. made...

Radially inward turbulent particle flux is observed in the core region of target plasma Large Volume Plasma Device where electron temperature gradient (ETG) driven turbulence conditions are satisfied with threshold, ηETG=Ln/LT>2/3 [Mattoo et al., Phys. Rev. Lett. 108, 255007 (2012)]. The mode satisfies scale length and frequency ordering ETG (k⊥ρe≤1≪k⊥ρi,Ωi<ω≪Ωe), k⊥ perpendicular wave vector, ρe ,ρi Larmor radii ion, respectively, Ωi,Ωe, ω gyro frequencies, frequency,...

This paper discusses a large area multifilamentary plasma source used in the volume device. source, based on directly heated filaments, is simple design and produces quiescent (δn/n≈1%) plasmas of high density (⩽1018 m−3), low temperature (∼1–2 eV), over (≈1.1 m2) (≈1.6 m3). With investment ≈40 kW (1350 A, 30 V) power, filaments are to ≈2000 K yield emission current ∼1 A cm−2 at filament surface. Experiments demonstrate that this suitable for carrying out electromagnetic wave excitation...

This paper reports experimental investigations of nonlinear electron magnetohydrodynamic (EMHD) structures the size skin depth. It is shown that difficulty exciting EMHD with k⊥de∼1 not related to any specifics antenna–plasma coupling mechanisms but a general attenuation scaling antenna size. Formation null-point or mirror geometry contribution from current leads effects in case k⊥de≪1. However, there weakening nonlinearity k⊥de∼1. Observations indicate reconnection rates may be independent...

This paper reports experimental and theoretical investigations on plasma turbulence in the source of a Large Volume Plasma Device. It is shown that highly asymmetrical localized thin rectangular slab strong excited by loss cone instability. The position coincides with injection line primary ionizing energetic electrons. Outside slab, core, weaker factor 30. consists oblique [θ=tan−1(k⊥/k||)≈87°] Quasi-Longitudinal (QL) electromagnetic whistlers broad band 40kHz<f≤80 kHz k⊥∼1.2 cm−1...

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

An automated electro-mechanical system for the positioning of plasma diagnostics has been designed and implemented in a Large Volume Plasma Device (LVPD). The consists 12 assemblies, which are orchestrated using Modbus communication protocol on 4-wire RS485 communications to meet experimental requirements. Each assembly lead screw-based mechanical structure, Wilson feed-through-based vacuum interface, bipolar stepper motor, micro-controller-based drive, optical encoder online correction...

This paper describes 5 kA, 12 ms pulsed power supply for inductive load of Electron Energy Filter (EEF) in large volume plasma device. The is based upon the principle rapid sourcing energy from capacitor bank (2.8 F/200 V) by using a static switch, comprising ten Insulated Gate Bipolar Transistors (IGBTs). A suitable mechanism developed to ensure equal sharing current and uniform distribution during operation these IGBTs. Safe commutation EEF ensured proper optimization its components...

Plasma potential measurements using a compensated center tapped emissive probe (CTEP) in quiescent plasma () of large volume device (LVPD) are presented. The CTEP shows distinct advantage over conventional (CEP) because measurement capability, independent electronics and operating conditions CEP. Its ability measuring continuous, uninterrupted (DC fluctuations) for pulsed DC discharges gives it other configurations. Also, its push fit design allows easy replacement without realizing frequent...

The data acquisition and control system (DACS) implementation for laboratory plasma experiments is a challenging task, develops gradually over time due to the: (a) rapidly evolving requirements driven by the new findings, (b) application of ideas experiments, (c) interaction software with specialized hardware (d) scales measurement controls. This motivates development based on flexible modular architecture scientific computing. We have broadly classified it as: base design dealing testing...

The electrostatic particle flux is measured in the presence of obliquely propagating quasi-longitudinal (QL) whistler turbulence (ωci<ωLH≈ω<ωce) large-volume plasma device (LVPD). QL observed with frequency band between 40 and 100 kHz, characteristic wave numbers k∥≪k⊥ are excited by reflected energetic electrons via loss cone (localised mirror type magnetic geometry) formation a transverse field [BEEF(x̂)] electron energy filter axial LVPD [Bo(ẑ)]. effect strength on radial...

Abstract We report low-frequency electromagnetic turbulence in large-volume plasma devices a region that receives magnetically screened plasma. The magnetic screen is produced by the activation of large solenoid generates strong field ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>B</mml:mi> <mml:mtext>EEF</mml:mtext> </mml:mrow> </mml:msub> </mml:math> ) transverse to background axial <mml:mi>z</mml:mi> ). strength variation...

Abstract We present a topical review of the detailed experimental investigations Electron Temperature Gradient (ETG) instability-induced turbulence and associated transport that have been carried out in Large Volume Plasma Device (LVPD) at Institute for Research. These results pertaining to high beta plasma are supported by theoretical modeling their significance with relation earlier ETG discussed. The removal non-thermal electrons control electron temperature gradient, $$\nabla {T}_{e}$$...

Abstract Conventional electrostatic probes are commonly used for measuring the plasma parameters like density, electron temperature, potential and floating respectively in a laboratory to unveil physical processes of relevance magnetosphere fusion plasmas. With such probes, real-time measurement temperature its fluctuating AC component becomes very difficult. These measurements significant as they directly give measure energy flux hence can be utilized estimating turbulence-induced loss any...

Nonlinear coherent structures on a cross-field plane are observed in the linear Large Volume Plasma Device (LVPD). The determined from conditional averaging of floating potential signals taken by an array Langmuir probes that is moved to different radial locations shot-to-shot. reference two single measure both ion saturation current and at fixed location matrix 31×9 observation locations. Our measurements show anti-correlated, structure sizes elongated direction with cross field size few cm...

This paper describes the design, construction, and calibration of an electric dipole probe demonstrates its capability by presenting results on measurement field excited a ring electrode in Large Volume Plasma Device (LVPD). It measures vacuum plasma conditions frequency range lying between . The show that it 2 mV cm−1 for developed works principle amplitude modulation. signal is transmitted through carrier 418 MHz, much higher than available sources noise present surrounding environment....