Thermally excited Trivelpiece–Gould modes as a pure electron plasma temperature diagnostic

Abstract

Thermally excited plasma modes are observed in trapped, near-thermal-equilibrium pure electron plasmas over a temperature range of 0.05ϽkTϽ5 eV. The modes are excited and damped by thermal fluctuations in both the plasma and the receiver electronics. The thermal emission spectra together with a plasma-antenna coupling coefficient calibration uniquely determine the plasma ͑and load͒ temperature. This calibration is obtained from the mode spectra themselves when the receiver-generated noise absorption is measurable; or from separate wave reflection/absorption measurements; or from kinetic theory. This nondestructive temperature diagnostic agrees well with standard diagnostics, and may be useful for expensive species such as antimatter.

TG wave autoresonant control of plasma temperature

“…This makes the modes very difficult to interpret for the temperature measurements. In other experiments, thermally-excited fluctuations in axial motion of plasma particles have been used as a basis for temperature diagnostics [7,8]. This completely passive diagnostics has many appealing features, but, due to the transient nature of fluctuating modes, their accuracy of frequency measurements is not high enough to serve in our case as a definitive diagnostic tool.…”

Electron plasma expansion rate studies on the Electron Diffusion Gauge experimental device

“…Pure electron plasmas are trapped in the Electron Diffusion Gauge ͑EDG͒ experimental device, [1][2][3][4] a cylindrically symmetric, Malmberg-Penning trap [5][6][7][8][9][10][11][12] with inside diameter I.D.= 2 ϫ R w = 5.08 cm. Malmberg-Penning traps have a uniform magnetic field parallel to the common axis of several cylindrical electrodes, and particles with the same sign of charge can be confined by charging two nonadjacent electrodes to a sufficiently large voltage.…”

Experiments with nonneutral plasmas

“…Recent experiments have measured thermal level fluctuations of plasma modes, or more precisely Trivelpiece-Gould modes, in pure electron plasmas [23]. Figure 6 shows the result of a transmission experiment in which a sinusoidal voltage is applied to a driver electrode, and the response is measured on a well-separated receiver electrode.…”

“…temperature measurements is good, the fluctuation measurements can be used as a non-destructive temperature measurement [23]. Figure 10 shows a schematic diagram of a pure electron plasma experiment that can be used to model the ideal (incompressible and inviscid) flow of a neutral fluid [7].…”