New Doppler Backscattering Diagnostic Designed for Pegasus-III Fusion Experiment
Researchers have designed a multifunctional Doppler backscattering (DBS) diagnostic system for the Pegasus-III tokamak experiment that will measure plasma flows, electron density fluctuations, and magnetic pitch angles. The system uses a tunable Ka-band source with advanced quasioptical steering capabilities to probe ion-scale density fluctuations across a range of plasma positions. This diagnostic will support both fundamental understanding of DBS instrumentation and Pegasus-III's research goals, including solenoid-free plasma initiation and mode conversion heating.
A new Doppler backscattering diagnostic has been designed for the Pegasus-III tokamak experiment to advance both diagnostic science and fusion research objectives. The system employs a single-channel, tunable Ka-band source with a corrugated horn antenna and homodyne receiver, featuring innovative quasioptical elements including a rotatable spinner for polarization selection and a 2D-steerable mirror. Using beam-tracing simulations, the design demonstrates capability to measure ion-scale density fluctuations with wavenumbers between 1 and 8 cm⁻¹ across the outer core plasma region to just beyond the last-closed flux surface. The system includes additional toroidal steering to enable magnetic pitch angle measurements, which are critical for locating mode conversion windows that affect heating and current drive efficiency. This multifunctional approach will support understanding of DBS instrumentation while enabling key Pegasus-III research directions such as solenoid-free plasma initiation.
What different sources said
- arXiv physicsCenter
Design of a multifunctional Doppler backscattering diagnostic for the Pegasus-III Experiment
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