Spatial heterodyne spectroscopy for fast local magnetic field measurements of magnetized fusion plasmas
A novel spectroscopy diagnostic for measuring internal magnetic fields in high temperature magnetized plasmas has been developed. It involves spectrally resolving the Balmer- α (656 nm) neutral beam radiation split by the motional Stark effect with a spatial heterodyne spectrometer (SHS). The unique combination of high optical throughput (3.7 mm2sr) and spectral resolution (δλ ~ 0.1 nm) allows these measurements to be made with time resolution $$\ll$$1 ms. The high throughput is effectively utilized by incorporating a novel geometric Doppler broadening compensation technique in the spectrometer. The technique significantly reduces the spectral resolution penalty inherent to using large area, high-throughput optics whilemore »