Status of high harmonic fast wave experimental campaign on Large Plasma Device.

The high harmonic fast wave (HHFW) project on Large Plasma Device (LAPD) at University of California, Los Angeles (UCLA) is led by TAE Technologies in collaboration with UCLA, Oak Ridge National Laboratory (ORNL), and Princeton Plasma Physics Laboratory (PPPL); the main objective of this project is to utilize LAPD as the testbed to study fast waves' coupling and propagation in D plasma, as well as to validate full wave Petra-M code with experimental measurements. The HHFW antenna on LAPD is a high-power-capable, phased-array 4-strap antenna. Each strap has an individual set of RF amplifier, transmission line, dual directional coupler, and matching network; in addition, there is a decoupler and a phase detector connected between two adjacent coaxial transmission lines near the feedthrough of the HHFW antenna. The second HHFW experimental campaign on LAPD was conducted in November 2021, right after the upgrade and commissioning of new LaB6 sources, which are routinely used to generate target plasmas for a variety of plasma physics studies. The major tasks of this HHFW campaign are: 1. install, calibrate and commission RF components such as matching networks, directional couplers, V/I probe, decouplers, and phase detectors (these components were not ready to install during the first HHFW experimental campaign); 2. integrate all sort of RF signals into LAPD data acquisition system; 3. tune impedance matching network to increase the RF power coupled into D plasma; 4. study phased-array HHFW antenna-plasma coupling by varying antenna-plasma distance and the phase shift between straps; 5. revisit the study of HHFW propagation in D plasma by scanning fast wave B filed at near field (in front of antenna) and far field (4 m away from the antenna center), as well as in the vertical plane and horizontal plane of the machine. Detailed experimental results will be presented. [ABSTRACT FROM AUTHOR]