Beam power transmission and grid loading characteristics of a two‐stage neutral beam source are presented. The dependence of power deposition on the target, the grids, and the gas cell was studied over a wide range of extraction perveance values with the accel‐to‐extraction gap field ratio as the other parameter. The results show that the power transmission improves remarkably with increasing field ratio. For sufficiently large field ratios (≈2.5), more than 80% of the input IV power was collected on a target located 4 m downstream and subtending 2 ° half angle to the source. The sum of the grid loading is approximately double that of single‐stage accelerators; the plasma grid loading is the highest, followed by ground grid, accel grid, and extraction grid in that order.