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Lebedev, O.

Particle Dynamics In Accelerators And Storage Rings, Cooling Methods, New Methods Of Acceleration

NARROW-BAND FEEDBACK SYSTEM TO DAMP TRANSVERSE COHERENT OSCILLATIONS OF BEAM IN THE U70

O. Lebedevª, S. Ivanov, N. Ignashin, S. Sytov

Institute of High Energy Physics, Protvino, Russia

Abstract

Resistive-wall transverse coherent instability shows up as a major adverse factor in running the U70 proton syn-chrotron of IHEP-Protvino. The 10th azimuthal spatial harmonic of coherent beam perturbation is the worst one prone to a strong instability. To damp this particular beam mode selectively, a dedicated narrow-band feedback cir-cuit has been developed. All of its hardware (comprising beam pickup and kicker plus analogue processing elec-tronics) is housed in one and the same straight section of the ring lattice, the feedback circuit configuration thus being the local one. Such a straightforward layout mini-mizes inherent time delays and eases closing the two feedback loops servicing horizontal and vertical direc-tions. The paper contains a brief technical specification of the damping system. Experimental results acquired during its turning on and beam-testing are outlined.

ª – corresponding author

Paper 

21

RF Acceleration Systems

UPGRADE OF FEEDBACK LOOPS IN ACCELERATING CAVITIES OF U70

A. Markinª, V. Chubrik, S. Ivanov, O. Lebedev, I. Sulygin

Institute of High Energy Physics, Protvino, Russia

Abstract

The entire accelerating system of the U70 proton syn-chrotron of IHEP-Protvino comprises 40 identical ferrite-loaded cavities yielding 10 kV per gap max [1]. To ensure control over amplitude and phase of RF voltage across the each accelerating gap, two feedback loops per cavity are employed – for automatic voltage amplitude (shortly, AVC) and automatic resonant frequency (AFC) controls. Attaining higher intensity and better quality of beam in the U70 depends upon operational performance of the AVC and AFC circuits in question. To this end, these cru-cial sub-systems were recently renovated so as to imple-ment the up-to-date hardware and electrical-circuit solu-tions. The paper contains a brief technical specification of the thus updated feedbacks. Experience acquired during their turning on and beam-testing results are presented.

ª – corresponding author

Paper 

221