Experimental Estimation for Beat-Wave Current Generation in an Unmagnetized Plasma and Preliminary Results

Beat-wave current generation experiment in a high density compact torus (CT) is being conducted on CTIX using CO$_{2}$ lasers. Tunability of the CO$_{2}$ lasers provides many options for the wave-particle interaction experiment at a variety of plasma densities with plasma frequency in THz range. For example strong lines such as 9R(12) and 9R(30) could be chosen for an easily obtainable density of 1.28x10$^{15}$cm$^{-3}$. After restoration, two Lumonics CO$_{2}$ lasers are expected to produce approximately 100MW output power in a 50ns pulse. The amount of energy transfer from laser to plasma is determined by the laser power intensity, and by the CT density scale length [1]. The desired power density can be achieved by designing a suitable optical focusing system. In addition, the CT density can be matched to the beat-wave frequency by appropriately selecting the plasma operating conditions and timing. Extensive testing of the Marx banks and pre-ionization boards was done under a variety of operating conditions. Other preliminary results and plans for the wave-particle interaction experiment will also be reported. [1] A. N. Kaufman, B. I. Cohen, PRL, 30 1306 (1973)