A 15 MeV proton diagnostic that is patterned after the ASDEX proton probe is presently being fabricated for the DIII-D tokamak. A bellows assembly inserts a silicon detector into the vacuum for plasma operation and retracts it for baking. The detector preamplifier is situated in a reentrant tube (at atmosphere) beside the detector; electrically, the whole assembly is referenced to vessel potential. Orbit calculations in realistic magnetic field geometries predict a proton detection efficiency of O(10{sup {minus}7}). The diagnostic will be used for burnup studies at high {beta} and particle transport studies in the H-mode. 25 refs., 4 figs
