The Coherent Particle-Oscillation Excitation System at the VEPP-4M Collider

Resumo

A system for excitation of coherent oscillations of a bunch of particles was created to study the beam dynamics at the VEPP-4M electron-positron collider; it consisted of a pulse generator, a beam deflection device (kicker), and a control and synchronization system. The system has two independent channels for the excitation of horizontal and vertical oscillations and makes it possible to excite oscillations of a given bunch of particles. For observations of beam oscillations, a system for measuring the position of the beam in the reverse mode is used, as well as a fast multichannel photomultiplier tube (profilometer). The design and results of operation of high-voltage nanosecond shock generators with a current pulse duration of 200–250 ns at the base, a voltage up to 25 kV and a current up to 2 kA are described. Using constructive solutions, the durations of the fronts of the output pulses were reduced, which made it possible to avoid the excitation of neighboring bunches. Testing the generators for their working loads gave the following results: a horizontal impact pulse of 30 ns and a vertical impact of 50 ns, a horizontal impact pulse tip duration of ~20 ns, a maximum pulse amplitude of 25 kV, and a time instability (jitter) of ±1 ns. The results of measurements of the beam parameters obtained using this system are presented.