Invited Paper PS2-TuA3
PM Helicons: A Better Mousetrap

Tuesday, October 19, 2010, 2:40 pm, Room Galisteo

Helicon discharges are known to very efficient in generating high plasma densities at low pressures for such applications as etching. The reason for this efficiency is that helicon plasmas depend on resonant waves in a magnetic field which couple the rf energy into electrons in a complicated way involving nonlinear physics. To generate the magnetic field, commercial helicon reactors employ large, heavy electromagnets and a correspondingly large dc power supply to drive them. A new type of helicon discharge has been developed that uses the remote field of annular permanent magnets (PMs) and an array of small tubes that incorporate constructive interference of a reflected helicon wave [1-3]. With 3kW at 13.56 MHz, an 8-tube test device has produced argon plasmas of density 2-6 x 10¹¹ cm^-3 over ~20 x 50 cm areas with +/- 3-5% uniformity [4]. The source needs only 15 cm of vertical space. A code HELIC is used for the design of the wave properties, and a new code EQM has recently been developed to predict the equilibrium profiles of plasma and neutral densities and of electron temperature, With 27.12 MHz it is possible to design a very compact plasma thruster for spacecraft.

*mail to:ffchen@ee.ucla.edu

1. F.F. Chen and H. Torreblanca, Plasma Phys. Control. Fusion 49, A81 (2007).

2. F.F. Chen and H. Torreblanca, Phys. Plasmas 16, 057102 (2009).

3. F.F. Chen and H. Torreblanca, Plasma Sources Sci. Technol. 16, 593 (2007).