Page 2 - Overview of TAE technologies’ HHFW project on LAPD

array antenna, and a variety of plasma diagnostics that allow volumetric measurements with computer-controlled probes, the LAPD facility [5] at UCLA is uniquely and ideally positioned for the proposed experimental studies.
The topics to be addressed on LAPD include: (a) launching of HHFW with desired wave spectra of k// (or n// parallel refractive index) by precisely controlling relative phasing between antenna straps; (b) experimentally validating fast wave coupling and propagation predicated by cold-plasma full wave modeling; (c) optimizing wave coupling by exploring the effects of edge density profiles, antenna-plasma distance, and phasing between straps.
HHFW ANTENNA SIMULATION, DESIGN, FABRICATION, AND INSTALLATION
Based on available ports and operational parameters of LAPD, a high-power-capable phased-array (4-strap) antenna has been calculated and designed through collaboration amongst TAE, ORNL, ASIPP, and UCLA. Antenna 3D electromagnetic simulations with MicroWave Studio (MWS) software was performed by ORNL RF group. For high power operation (200 kW for each strap), the key parameters of antenna geometric structure that need to be optimized include strap length and width, distance between straps, septa thickness and gap, Faraday screen transparency and element sizes, slot height and length, and gap between strap backplane to back wall.
(a) (b)
FIGURE 1. Calculated antenna vacuum spectrum at 10 MHz for the phasing of (a) [0, π, 0, π]; (b) [0, π/6, π/3, π/2].
(a) (b)
FIGURE 2. Newly built phased-array (4-strap) HHFW antenna for LAPD (a) outline of antenna mechanical design; (b) photo of HHFW antenna installed in LAPD vacuum vessel.
There is a trade-off between the choice of wave frequency and relative phasing. As shown in Figure 1, for a given frequency (10 MHz at 1 kG), antenna k-spectrum can be tailored by varying phasing between straps. To obtain a
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