Measurement of the Local Electron Temperature in Self-Compressed Plasma Stream

Abstract

The local electron temperature measurements with the double electric probe in the compression zone are presented. Electric probes make it possible to measure the electron temperature with a reasonably good spatial resolution. Double electric probe application for electron temperature measurements in the dense self-compressed plasma stream is discussed. We have shown experimentally that the electric probe operates in a diffusion regime.

Structure and local parameters of self-compressed plasma streams in external magnetic field

“…In the case when the electron energy distribution function (EEDF) is bi-Maxwellian with two well--separated temperatures [17], the results can be obtained by straight-line fi ts on the semi-logarithmic current-voltage characteristic. The two-temperature Maxwellian EEDF near the compression zone of the MPC plasma streams has been discovered for the fi rst time in our previous experiments [12].…”

“…Nevertheless, the possible local disturbances of plasma introduced by probes should be precisely analyzed. We have shown earlier that the double probe operates in the diffusion regime at a range of plasma parameters typical for the MPC discharge [12]. However, the value of the ion saturation current measured by the probe turned out to be lower than Langmuir's current due to the attenuation in the near-probe sheath.…”

“…A set of electric probes was used for the measurements of the local electron temperature and radial component of the electric fi eld. The magnetic coil installed on the MPC [11,12] produces an axial magnetic fi eld of up to 0.4 T inside the channel. The magnetic coil is 17 cm in length and 15 cm in diameter.…”

“…No systematic experimental investigations were performed up to now to analyze these issues. Our fi rst experimental studies with the MPC operating in the external axial magnetic fi eld are available in the literature [11,12]. Earlier experiments have shown that the plasma fl ow generated by the MPC has a rather complex spatial structure.…”

“…More importantly, the ratio of the intensities of different spectral lines or the pressure balance equation used previously [6,7] for electron temperature measurements cannot give its local value, especially, in the near-axis region where the compression zone forms. In order to be able to conduct local measurements, we have designed a set of magnetic and double electric probes [11,12]. Double electric probes are very useful for measurements of the electron temperature with good temporal and spatial resolution in various devices [13][14][15][16].…”