Advanced Thomson scattering system for high-flux linear plasma generator

Abstract

An advanced Thomson scattering system has been built for a linear plasma generator for plasma surface interaction studies. The Thomson scattering system is based on a Nd:YAG laser operating at the second harmonic and a detection branch featuring a high etendue (f /3) transmission grating spectrometer equipped with an intensified charged coupled device camera. The system is able to measure electron density (n e ) and temperature (T e ) profiles close to the output of the plasma source and, at a distance of 1.25 m, just in front of a target. The detection system enables to measure 50 spatial channels of about 2 mm each, along a laser chord of 95 mm. By summing a total of 30 laser pulses (0.6 J, 10 Hz), an observational error of 3% in n e and 6% in T e (at n e = 9.4 × 10 18 m −3 ) can be obtained. Single pulse Thomson scattering measurements can be performed with the same accuracy for n e > 2.8 × 10 20 m −3 . The minimum measurable density and temperature are n e < 1 × 10 17 m −3and T e < 0.07 eV, respectively. In addition, using the Rayleigh peak, superimposed on the Thomson scattered spectrum, the neutral density (n 0 ) of the plasma can be measured with an accuracy of 25% (at n 0 = 1 × 10 20 m −3 ). In this report, the performance of the Thomson scattering system will be shown along with unprecedented accurate Thomson-Rayleigh scattering measurements on a low-temperature argon plasma expansion into a low-pressure background.

Modeling the reduction of gross lithium erosion observed under high-flux deuterium bombardment

“…1. These values were obtained by measuring n e and T e profiles with 1 Hz frequency via Thomson scattering [20] and linearly interpolating between each time point. Prior to the first measurement point at t = 1 s, n e and T e were assumed proportional to the magnet current I B .…”

The occurrence and damage of unipolar arcing on fuzzy tungsten

“…The experimental setup of Magnum-PSI plasma device is described in [12]. In MAGNUM-PSI a plasma is generated with a typical high plasma density ( ) and electron temperature of 1-2 eV (measured by a Thomson Scattering system [13]). The plasma is radially confined by the magnetic field of and flows to a water-cooled, electrically biased target, achieving a particle flux of -, ion energy of -e , and surface temperature of -.…”

Collective Thomson scattering system for determination of ion properties in a high flux plasma beam

“…1) are presented. A combination of TS 10,11 and CTS enables the simultaneous measurement of electron temperature (T e ), electron density (n e ), ion temperature (T i ) and plasma velocity (v plasma ) with high accuracy (currently 25% at Pilot-PSI, but <15% for Magnum-PSI system).…”