Abstract
The simulation survey of TAE Technologies has demonstrated that high harmonic fast wave (HHFW) heating is a promising method for core electron heating of FRC plasma. This study mainly describes the HHFW antenna mechanical design and assembly on the basis of the results of electromagnetic simulations performed by Oak Ridge National Laboratory (ORNL), the available port dimensions, and antenna installation position of the LAPD. Compared to the original scheme, this antenna is also optimized in the design. It is found that the E field distribution of optimized antenna becomes even, and the maximum electric field decreases by approximately 14%. The current on the antenna box and FS is reduced after optimization, whereas the maximum J density decreases from 53.3 kA to 14.5 kA. The reflection performance of the port at 30 MHz is also improved after the structural optimization; The k// spectrum distribution is sharper at the monopole phase (0, 0, 0, 0) and dipole phase (0, π, 0, π) and (0, 90, 270,180) than other phases. The optimized antenna can obtain a maximum |k//| spectrum, which peaks about |k//| = 30 m−1 at the dipole phase (0, π, 0, π). The analysis results and assembly strategy can provide useful reference and guidance for the study of HHFW antenna design and fabrication in LAPD or other magnetic confined fusion devices.
Highlights
Antennas can transform guided waves propagating along transmission lines into electromagnetic waves propagating in unbounded media, or vice versa
A recent survey by Tri Alpha Energy (TAE) Technologies indicates that high harmonic fast wave (HHFW) heating, which has been successfully adapted to high beta, over-dense spherical Tokamak plasmas, such as the National Spherical Torus Experiment (NSTX), for the experiments of core electron heating and off-axis current drive, can balance the conflict between good wave accessibility and efficient power damping of electrons [5, 6]. is discovery motivates a project on the experimental study of HHFW antenna-plasma coupling and wave propagation on a reliable test bench, such as the large plasma device (LAPD) at the University of California-Los Angeles (UCLA), before
Science and Technology of Nuclear Installations the method of HHFW electron heating is employed on the C-2W, an advanced beam-drive field-reversed configuration (FRC) device recently built at TAE. erefore, in the framework of the collaboration agreement between TAE and Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP), ASIPP is in charge of the design and fabrication of a high-power capable, phased array HHFW antenna for the radio frequency (RF) project of TAE on the LAPD at UCLA
Summary
Antennas can transform guided waves propagating along transmission lines into electromagnetic waves propagating in unbounded media, or vice versa. Antenna is an important method of heating plasma in magnetic confined fusion devices. Science and Technology of Nuclear Installations the method of HHFW electron heating is employed on the C-2W, an advanced beam-drive field-reversed configuration (FRC) device recently built at TAE. Ion cyclotron range of frequencies (ICRF) antennas have been used as an efficient heating method in many tokamak devices, such as the Tokamak Fusion Test Reactor (TFTR), Joint European Torus (JET), Experimental Advanced Superconducting Tokamak (EAST), and ITER. E RF rectification sheath potential reduces the heating performance of the ICRF antenna through the acceleration of ions and causes a local hot spot on the ICRF structure, which has been observed during the experiments hosted in tokamaks. An LAPD was designed with the capability to diagnose and model the effect of RF rectification sheath potential and impurity production on an ICRF antenna. Some experiments on an LAPD were proposed to investigate the sheaths caused by an actively powered RF antenna [16]
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