Energy and Particle Confinement Studies on WHAM using Hα Intensity Measurements

The Wisconsin HTS Axisymmetric Mirror, WHAM, is a new experiment exploring the physics of axisymmetric mirror confinement [1]. A prototype Hydrogen Balmer-α detector array has been developed to explore particle and energy confinement in WHAM. The array collects Hα light along 5 chords at the midplane of the machine. Measurements are Abel inverted to attain an Hα emissivity profile. The system is calibrated with an integrating sphere to allow for absolute measurements of Hα emissivity. The Hα array allows for the calculation of particle source rate and charge exchange power loss. Energy and particle balance studies as well as resulting confinement times are shown for various operating configurations. Hα array measurements are also compared to predictions by the 1D neutral transport code KN1DC to attain first estimates of neutral transport in WHAM [2, 3].

[1] D. Endrizzi et al. J. Plasma Phys, 89 975890501 (2023).

[2] B. LaBombard., MIT PSFC. Rep. RR-01-3 (2001).

[3] B. Biswas et al., Sherwood (2025).