The MST Heavy Ion Beam Probe

A Heavy Ion Beam Probe (HIBP) has been installed on MST to obtain nonperturbing, local measurements of equilibrium and fluctuating core parameters. The 200kV ion accelerator, 100kV energy analyzer, most vacuum and electronic systems are from the ATF and TEXT HIBP's. However, each component has been reconditioned and/or rebuilt to utilize subsequent HIBP design advances. Unique to the MST-HIBP are three cross-over sweep systems which make measurements feasible at essentially all plasma radii. The broad range of possible probing angles, energies and ion species and the reproducibility of MST plasmas make it possible to address several implementation challenges. These include high levels of plasma and UV flux at MST ports, which prompted design and implementation of magnetic apertures to protect the sweeps. Also, the magnetic field being largely produced by the plasma makes determination of measurement locations exclusively from trajectory calculations difficult. This motivated the design of MST-wall mounted detectors for system alignment, calibration, and subsequent development of improved confining field models.