We studied the pressure‐dependent peak intensity and time history of the 388.9‐nm radiation emitted from the 33P→23Stransition of helium at pressures ranging from 10−2to 55 Torr, following excitation with a short (15 nsec) and intense (25 kA) burst of high‐energy (500 keV) electrons. From the decay of radiation we determined the short‐lived and long‐lived decay components and the values of the effective direct‐excitation cross section of the 33Plevel at several gas pressures. At low pressures ( p?4 Torr) we also determined the quenching cross section of the 33Plevel by ground‐state helium collisions.