The presence of a toroidal field ripple greater than 2% in the Alcator A tokamak allows for the trapping and rapid ∇B drift loss of ions in the port gap of the toroidal field magnet. The resulting depletion of high-energy ions is observed by perpendicular charge-exchange measurements and may point to a significant energetic ion loss mechanism in Alcator A. Smaller ripple, larger minor radius and higher toroidal field lead to greatly reduced losses in Alcator C.