Three independent techniques are used to measure the mean ion energy in an intense ion beam accelerated with a standard pinch‐reflex diode. The experimental accelerating voltage agrees with a numerical simulation. The resulting deuteron energy is consistent with the activation results of a BN target and with the hydrodynamic motion of subrange and overrange aluminum foils bombarded by the beam. The accelerating voltage is also used to compare the experimental and computed neutron yields when the beam strikes a CD2target. The total ion current measured with an electrical diagnostic is five to ten times greater than the corresponding deuteron component. This is significantly greater than values reported previously.