Thomson scattering in low temperature helium plasmas of a magnetic multipole plasma source

Abstract

Measurements of electron density and temperature of helium plasmas in a cw running magnetic multipole plasma source by repetitively laser-pulsed 90° Thomson scattering are reported. This is the first experiment in which this technique has been applied to such plasmas. Measurements are performed at a helium gas pressure of pg = 5 Pa, the discharge voltage was Ud = 100 V, the discharge current was 5 A ≤ Id ≤ 30 A, and the cathode heating current was 80 A ≤ Ih ≤ 140 A. Electron energy distribution functions obtained from the Thomson scattering spectra are studied. The obtained plasma parameters are electron temperature 1.5 eV ≤ kTe ≤ 5 eV and density 1012 cm−3 ≤ ne ≤ 4 × 1012 cm−3, respectively. The sensitivity of detection of the experiment is in the range of 109 electrons and the accuracy of the electron temperature and electron density are specified to 15% and 20%, respectively. In addition, the neutral density and helium gas temperature are obtained from the Rayleigh component of the scattered spectra. Langmuir probe measurements are performed under the same plasma conditions and a comparison of the results with Thomson scattering shows good agreement between the two diagnostics.

Updating Plasma Scattering of Electromagnetic Radiation

“…Measurements have been made on: impulse breakdown plasma in atmospheric air, Uchino et al [22]; electron cyclotron resonance (ECR) sources, Bowden et al [23]; radio frequency inductively coupled sources, Hori et al [24]; magnetic neutral loop discharges, Sakoda et al [25]; capacitatively coupled radio frequency sources, Wesseling and Kronast [26]; micro-discharge plasmas, Noguchi et al [27]; neon-mercury positive column, Bakker and Kroesen [28]; atmospheric argon plasma, Zaidi et al [29]; tin vapor discharge Kieft et al [30]; microwave plasma torch, van der Mullen et al [31]; and a magnetic multipole, Maurmann et al [32].…”

“…During the pre-pinch phase, the electron temperature and density are, respectively, in the range of 5 -30+ eV, and 10 23 -10 24 m -3 . Measurements on such plasmas have been made by Kieft et al [30]. Noguchi et al [27] and Hassaballa et al [32] made measurements in small scale (0.1 -1 mm) plasmas of a micro-discharge, as used in a plasma display.…”

Development of double-pulse lasers ablation system for generating gold ion source under applying an electric field

“…Recently, laser ablation (LA) of solid targets has been studied by installing lasers of different pulse durations in nanosecond regime [8]. In addition, application of low pressure of gas discharges are widely used in plasma spraying, plasma polymerization, charged particle accelerators, plasma processing, plasma display panels, fabrication of thin films by sputtering and etching, surface treatments and light sources [9][10][11][12][13][14][15]. Most of these applications required good understanding of laser-ablation and generation of ion sources.…”

Development of a silver ion source using nanosecond pulses of a Nd:YAG laser at different wavelengths

“…This technique is becoming increasingly popular in applications such as switching high voltage electric discharges, material synthesis, cluster formation and thin film deposition [2][3][4]. A good understanding of PLA is so significant since it can be applied in the optimization of thin film deposition, laser induced electrical break down in electronics [5] and laser assisted ion implantation with ion acceleration [6][7][8][9][10][11][12]. Moreover, low pressure electrical discharges are applied in the areas of plasma processing, deposition of thin films by sputtering, plasma polymerization, etching, welding, cutting, plasma spraying, plasma display panels and light sources [13].…”