Ion-pumping mechanism in a pulsed Penning source:: application to the production of multiply charged ions

The neutral atom density of a low-duty pulsed Penning ionized-gauge ion source (PIGIS) is sharply pulsed, according to the pulsed ion current into the cathode, which should act as a periodic ion pump in the plasma column of PIGIS. A high yield of multiply charged ions (Ar8+, 250–300 eμA; Ar7+, ∼1000 eμA) can thus be obtained under a reasonably low gas pressure during a short time (of the order of millisecond), which is sufficiently long for injection (∼160 μs) into the heavy-ion medical synchrotron (HIMAC) at NIRS.