Production of Millimicrosecond Pulses by Radio-Frequency Sweeping of the Ion Beam in the Terminal of an Electrostatic Accelerator

Abstract

Apparatus has been installed in the high‐voltage terminal of the Brookhaven National Laboratory research electrostatic accelerator for production of ion current pulses in the millimicrosecond range by radio‐frequency sweeping of the beam across a limiting aperture between the ion source and acceleration tube. Proton and deuteron pulses with a full width at half‐maximum of about 4.5 millimicroseconds are presently available, with a pulse repetition time of 134 millimicroseconds and an average current of 1–2 microamperes. A simple electrostatic refractor rejects alternate pulses to give one pulse per rf cycle. The following advantages of this method are to be noted: (1) It minimizes the production of background radiations by ions which are not used on the target, (2) The reduced duty factor makes it potentially possible to correspondingly increase the instantaneous intensity during pulses. The usefulness of the system has been demonstrated by the measurement of the delayed deexcitation by γ emission of the first excited state in B¹⁰.