Status of neutral beam and supporting diagnostics on LTX-β

Neutral beam heating of LTX-β plasmas with flat temperature profiles have been observed. A challenging environment for efficient coupling of the 20 keV NBI, experimental confirmation of beam heating was achieved by optimizing plasma and beam parameters and increasing the beam tangency radius through an intentional misalignment of the ion source. The amount of observed heating remains below that predicted by NUBEAM modeling and is thought to be a result of a strong dependence on the variation in plasma and beam parameters during the discharge, along with the presence of tearing mode activity. Planned upgrades to re-aim the NBI from a tangency radius of 19 cm to 33 cm and extend the pulse length will enable more efficient beam coupling and stronger heating. The more robust coupling will relax the dependence on variations during a discharge and allow for experimental observation of heating at a wider range of plasma and beam parameters and up to the maximum beam energy of 20 keV. LTX-β is now in a vented maintenance phase during which a Neutral Particle Analyzer (NPA) and a 2D wire-calorimeter will be installed for diagnostic access to the coupled fast-ion population and beam profile for each discharge. The NPA (from UW-Madison) is being repaired and recalibrated, and the wire calorimeter is being designed and prototyped to be installed in the beam line between the beam source and vessel entry. These diagnostics and will give shot specific beam information which will further constrain beam deposition predictions. Modeling of each diagnostic and its repair/development status will be presented.