Effects of discharge current and voltage on the high density of metastable helium atoms

• 来源期刊: 中国物理（英文版）
• 关键词: Penning discharge hollow-cathode discharge metastable atoms electric field
• 年，卷（期）: 2003,（5）
• 页码范围: 495-501
• 页数: 7页
• 语种: 英文

摘要

Both hollow-cathode and Penning-type discharges were adopted to excite helium atoms to a metastable state.Experimental data indicate that Penning discharge is more suitable for generating high fractions of metastables in a low-density helium beam for laser-induced fluorescence technique in measuring electric fields at the edge of a plasma.The metastable density increases with increasing helium gas pressure in the range of 1.33× 10-2-66.7Pa. The highest metastable density of 3.8 × 1016m-3 is observed at a static gas pressure of 66.7Pa. An approximately linear relationship between the density of metastable helium atoms and the plasma discharge current is observed. Magnetic field plays a very important role in producing a high density of metastable atoms in Penning discharge.