PRODUCTION OF FAST ELECTRONS IN A PROTOTYPE HELIAC BY HELICON WAVES

The generation of plasma by helicon waves has been investigated in the Small Heliac Experimental Apparatus [Nucl. Fusion 25, 1485 (1985)]. E vidence for wave-particle interaction in both argon and helium is pres ented iri the form of observations of the electron distribution functi on. A high energy bump-on-tail feature is shown to coincide with the w ave phase velocity and with an energy corresponding to a large ionizat ion cross section. It is shown that the bump-on-tail feature may be re lated to the ionization capability of helicon waves and may be a resul t of some form of radio frequency current drive.