Light ion helicon plasma sources

• Main Authors: Carter, M D, Baity Jr, F W, Goulding, R H, Jaeger, E F, Chang-Diaz, F R, Squire, J P
• Format: Conference Proceeding
• Language: English
• ISSN: 0094-243X

Helicon plasma sources are capable of producing high density plasma using steady state solenoid or mirror-like magnetic fields with a wide variety of gases. Power to produce the plasma is supplied by various antenna configurations driven at frequencies typically ranging from 1 to 50 MHz. The ability to obtain high plasma densities with high fractional ionization using readily available, low-cost components makes the helicon an attractive plasma source for many applications including plasma rocket propulsion, fusion component testing, and materials processing. However, their operation can be a sensitive function of the magnetic field strength and geometry as well as the driving frequency, especially when using light feedstock gases, such as hydrogen or helium. This sensitivity can make it difficult to design a helicon source with the characteristics required for a specific application. This paper gives an overview of various helicon configurations, experimental observations, and modeling results, with an emphasis on high density operation using light ion species. Axial variations in the plasma parameters are also shown to play an important role in understanding the behavior of the Mini-RFTF device at Oak Ridge National Laboratory. (Author)