Supersonic ion beam driven by permanent-magnets-induced double layer in an expanding plasma

Kazunori Takahashi, Yutaka Shida, Tamiya Fujiwara, Kaoru Oguni

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


Plasma potential structures and ion-energy distribution functions are measured in a magnetically expanding radio-frequency plasma using permanent magnets (PMs) and in a geometrically expanding one, where the radio-frequency power and the argon-gas pressure are maintained at 250 W and 1 mtorr, respectively. In the magnetically expanding plasma, a rapid potential drop like a double-layer structure and a subsequent supersonic ion beam are detected by retarding field energy analyzers. On the other hand, a plasma potential structure following Boltzmann relation accelerates the ions in the geometrically expanding plasma. The comparison between the results in both cases indicates that the existence of the PMs is effective for the generation of the high-speed ion beam, where the mach number of the ion beam is increased to about 3.5 by using the PMs compared with the mach number of 2.3 in the operation mode of the geometrically expanding plasma.

Original languageEnglish
Pages (from-to)1532-1536
Number of pages5
JournalIEEE Transactions on Plasma Science
Issue number8 PART 2
Publication statusPublished - 2009


  • Double layer (DL)
  • Expanding plasma
  • Ion acceleration
  • Permanent magnets (PMs)
  • Plasma potential structures


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