Evidence of current free double layer in high density helicon discharge
- Centre for Energy Studies, Indian Institute of Technology, New Delhi 110016 (India)
- Department of Applied Sciences and Humanities, Dronacharya College of Engineering, Gurgaon 123506 (India)
- Department of Physics, Indian Institute of Technology, New Delhi 110016 (India)
This paper investigates the formation of double layer (DL) in helicon plasmas. In the experiment, argon plasma production is using the excitation of m = -1 helicon mode with magnetic mirror field with high mirror ratio of {approx}1:1.7. We have specifically used the radio frequency compensated Langmuir probe (LP) to measure the relevant plasma parameters simultaneously so as to investigate the details about the plasma production. The DL, which consists of both warm and bulk populations towards higher potential region and only dense bulk plasmas towards the lower potential region downstream the antenna, is present in the transition region. LP measurements also show an abrupt fall of density along with a potential drop of about 20 V and (e {Delta}V{sub p}/k T{sub e}) Almost-Equal-To 12 within a few cm. The potential drop is equal to the difference of the electron temperatures between the two plasma regions forming the DL, which is present in the plateau region of mirror, unlike in several prior studies on the DL formation in the region of strong gradients in the magnetic field. The DL is strong, current-free, electric double-layer with estimated thickness of about 10 Debye lengths.
- OSTI ID:
- 22113394
- Journal Information:
- Physics of Plasmas, Vol. 20, Issue 1; Other Information: (c) 2013 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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