科研之友
微信
新浪微博
Facebook
分享链接
摘要
In this paper, a diagnostic method for magnetized and unmagnetized laboratory plasma is proposed, based on impedance measurements of a short matched dipole. The range of the measured electron densities is limited to low density plasmas (10(12) - 10(15) m(-3)), where other diagnostic methods have strong limitations on the magnetic field strength and topology, plasma dimensions, and boundary conditions. The method is designed for use in both large-and small-dimension plasma (< 10 cm) without or with strong non-homogeneous magnetic field, which can be undefined within the probe size. The design of a matched dipole probe allows to suppress the sheath resonance effects and to reach high sensitivity at relatively small probe dimensions. Validation experiments are conducted in both magnetized (B similar to 170 G) and unmagnetized (B = 0) low density (7 x 10(12) m(-3)-7 x 10(13) m(-3)) low pressure (1 mTorr) 10 cm scale plasmas. The experimentally measured data show very good agreement with an analytical theory both for a non-magnetized and a magnetized case. The electron density measured by the matched dipole and Langmuir probes in the range of 7 x 10(12) m(-3) -7 x 10(13) m(-3) show less than 30% difference. An experimentally measured tolerance/uncertainty of the dipole probe method is estimated to +/-1% for plasma densities above 2 x 10(13) m(-3). A spatial resolution is estimated from the experiments to be about 3d, where d is the dipole diameter. The diagnostic method is also validated by comparing the measured plasma impedance curves with results of analytical modelling.
- 出版日期2015-7
