Practical helicon sources using permanent magnets

Helicon sources are known for efficient conversion of RF energy into plasma density, but the need for a large electromagnet has impeded commercial acceptance. A novel use of permanent magnets, in which the plasma is placed below, rather than inside, a ring magnet allow the plasma to be ejected toward the substrate. The dimensions of a single source and its magnet have been optimized by computation and tested experimentally. For large area coverage, a multiple-source array has been designed and tested. In this case, RF circuitry and coupling present problems that have been solved. Measurements show that an 8-tube module should produce 10$^{12}$/cm$^3$ density 7'' below a source only 6'' in height with 2-3{\%} uniformity. Stacked modules can cover arbitrarily large substrates with this new paradigm.