Measurement of Ion Parameters by Ion Sensitive Probe in ECR Plasma

Abstract

Ion parameters in electron cyclotron resonance (ECR) microwave plasma were measured by ion sensitive probe and were compared with the electron parameters obtained by double Langmuir probe. The effects of gas pressure and microwave power on the ion temperature and density were analyzed. The spatial distribution of the ion parameters was also investigated by the ion sensitive probes with a tunable radial depth installed on different probe windows along the chamber axis. Results showed that the ion density measured by the ion sensitive probe was in good agreement with the electron density measured by the double Langmuir probe. The influence of gas pressure on the ion parameters was stronger than that of microwave power. With the increase in working pressure, the ion temperature decreased monotonously with a decreasing rate larger than that at higher pressure. The ion density first increased to a peak (42.3×10 10 cm −3 ) at 1 Pa and then decreased. The ion temperature and density increased little with the increase in the microwave power from 400 W to 800 W. The plasma far away from the resonant point is found to be radially uniform.

Transient process of a spherical tokamak plasma startup by electron cyclotron waves

“…The simulation results of this model qualitatively agree with experimental observations [18] and support the physical images discussed above.…”

Scanning ion sensitive probe for plasma profile measurements in the boundary of the Alcator C-Mod tokamak

“…Ion temperature measurements have been performed with ISPs in Q-machines, 12, 13 tokamaks, 14,15,10,[16][17][18][19] mirror machines, 20,7,21 a simple plasma device, 22 a stellarator, 23,24 linear plasma devices, 25,8,26 an electron cyclotron heating plasma, 27 and even in an unmagnetized processing plasma. 28 One has also been used to estimate tokamak plasma transport coefficients.…”

Influence of Working Pressure on Ion Sensitive Probe Measurement in Microwave ECR Plasmas

“…A schematic diagram of the experimental apparatus and the axial (z) distribution of the magnetic field were described in Ref. [14]. In this experiment, the gas flow rate was 5 sccm and controlled by a mass flow controller, and the microwave power was 800 W. The ISP was set at z = 18 cm and the axis of ISP was along the radial direction of the chamber (perpendicular to the magnetic field).…”

“…The circuit for the plasma parameters measurement was described in Ref. [14]. A bias voltage of −1.5 V was applied between the Pand G-electrodes.…”