| AVS 58th Annual International Symposium and Exhibition | |
| Plasma Science and Technology Division | Tuesday Sessions |
| Session PS2-TuA |
| Session: | Plasma Diagnostics, Sensors and Control I |
| Presenter: | Yasuyuki Taniuchi, Tokai University, Japan |
| Authors: | Y. Taniuchi, Tokai University, Japan M. Utsumi, Tokai University, Japan M. Yanagisawa, Landmark Technology Corporation, Japan H. Shindo, Tokai University, Japan |
| Correspondent: | Click to Email |
A new diagnostic tool to measure plasma parameters as well as Electron Energy Distribution Function (EEDF) by a floating-emissive probe has been proposed[1], and a diagnostic system has been newly developed and applied to radio-frequency (RF) plasmas. It is generally difficult for a conventional probe method to measure EEDF in RF plasmas, because of the plasma potential fluctuation, particularly in the capacitive mode. The present method has an advantage that there is no need of an external compensation circuit and all measurements can be made in the floating condition. The method is based on measurement of the functional relationship between the floating potential change ΔVF and the heating voltage VH of emissive probe. If the plasma electrons are in Maxwellian, the equation can be obtained for the value of ΔVF as a practical and useful formula.[1]
It is important to know that the value of ΔVF contains information of electron energy distribution. In the experiment, the data of VF and ΔVF was measured in a 13.56 MHz RF plasma produced by single-loop antenna[2], as a function of VH. In the conditions of high RF power, the plasma mode was ICP and the measured values of ΔVF were in agreement with the theoretical value, stating that the plasma electron was in Maxwellian. The electron temperatures thus obtained were very consistent with those measured by Langmuir probe. The electron density was also obtained from the value of ΔVF near the plasma space potential and they were consistent with Langmuir probe data. Consequently, by using a new diagnostic system one can obtain the electron temperature and density, the plasma space potential and floating potential, as well as the EEDF in the floating condition of the probe. It should be stressed that this is the first success of floating probe to be able to measure all plasma parameters. One can also expect that the present method is applied to plasmas which are produced in insulated vessels.
References:
[1] K.Kusaba and H.Shindo, Review of Scientific Instruments, 78, 123503-1(2007).
[2] Y.Jinbo and H.Shindo, Applied Physics Express, 2, 016001-1(2009).