Experimental investigation of plasmas in a Q-machine

This report contains some of the results of the work in which I have participated during the past 2 years (1972-1974) in the Q-machine group at Risø. After a short introduction follows a theoretical discussion on collisionless damping of ion acoustic waves in the case where the derivative of the undisturbed velocity distribution function at the phase velocity equals zero. There follows a description of the Q-machine and of the preliminary results of the experiments on electron heating. Turbulence in a plasma is treated on the basis of dimensional arguments together -with an experiment on turbulence in a cusp Q-device in the next section. In the last section a simple theoretical derivation is giver of the Farley instability and a description of the first experimental investigation of this instability in a laboratory.