Plasma production from helicon waves

Journal Article · Mon Jul 01 04:00:00 EDT 1996 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.871712· OSTI ID:285596

Degeling, A W; Jung, C O; Boswell, R W; Ellingboe, A R ^[1]

---

1. Space Plasma & Plasma Processing Group, Plasma Research Laboratory, Research School of Physical Sciences and Engineering, Australian National University, Canberra (Australia)

Experimental measurements taken in a large magnetoplasma show that a simple double half-turn antenna will excite {ital m}=1 helicon waves with wavelengths from 10{endash}60 cm. Increased ionization in the center of the downstream plasma is measured when the axial wavelength of the helicon wave becomes less than the characteristic length of the system, typically 50{endash}100 cm. A sharp maximum in the plasma density downstream from the source is measured for a magnetic field of 50 G, where the helicon wave phase velocity is about 3{times}10{sup 8} cms{sup {minus}1}. Transport of energy away from the source to the downstream region must occur to create the hot electrons needed for the increased ionization. A simple model shows that electrons in a Maxwellian distribution most likely to ionize for these experimental conditions also have a velocity of around 3{times}10{sup 8} cms{sup {minus}1}. This strong correlation suggests that the helicon wave is trapping electrons in the Maxwellian distribution with velocities somewhat slower than the wave and accelerating them into a quasibeam with velocity somewhat faster than the wave. The nonlinear increase in central density downstream as the power is increased for helicon waves with phase velocities close to the optimum electron velocity for ionization lends support to this idea. {copyright} {ital 1996 American Institute of Physics.}

• OSTI ID: 285596
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 7 Vol. 3; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
HELICON WAVES
IONIZATION
PHASE VELOCITY
PLASMA PRODUCTION
TRAPPED ELECTRONS