Studies of the helicon plasma source with inhomogeneous magnetic field

The development of fusion facilities urges a search for materials resilient to plasma interaction. For simulations of plasma-material interaction a source of steady-state plasma is needed with sufficiently large plasma density at the level of 1013 cm-3 at least. A helicon plasma source was developed at the Budker Institute of Nuclear Physics SB RAS as a prototype of a powerful plasma source for future use in linear plasma devices for simulation of plasma-material interaction. Using Nagoya-type-III antenna hydrogen plasma is produced at 13.56 MHz frequency and with RF power up to 5 kW inside a quartz discharge chamber of 108 mm outer diameter and 400 mm axial length. Five coils installed outside the discharge chamber produce the magnetic field with two maxima at the ends of the chamber. The efficiency of the plasma production and the plasma density distribution are very sensitive to the geometry and strength of the magnetic field. In this paper, the results of the measurements of radial plasma density profiles and the electron temperature are presented. Their dependence upon the RF power, magnetic field geometry and strength, and gas pressure is discussed.