My research focus is to fi�nd out where and at what rates in the plasma charged fusion products, created inside of a fusion plasma, are created; this is called the product profile. A prototype diagnostic, or instrument, will be designed, constructed, assembled, and installed in the Mega Amp Spherical Tokamak (MAST) in the Culham Centre for Fusion Energy (CCFE) in the United Kingdom for data collection. Subsequent data analysis will be used to reconstruct the time-dependent charged fusion product profile from deuterium-deuterium reactions in the plasma. This will allow studies of plasma instabilities (such as toridal Alfven eigenmodes and fi�shbones) and neutral beam ion density profi�le effects on plasma stability. Plasma instability studies become vital to reduce hindrances on plasma performance so as not to impede efficient fusion energy production. The Proton Detector (or Charged Fusion Products Diagnostic) provides the foundation for future research in spherical tokamaks, especially as these devices upgrade to higher density plasmas. [Excerpt from Dissertation Proposal]