P.

25. V.S.Arbuzov, E.I.Gorniker, E.K.Kenjebulatov, A.A.Kondakov, S.A.Krutikhin, Ya.G.Kruchkov, I.V.Kuptsov, G.Ya.Kurkin, S.V.Motygin, V.N.Osipov, V.M.Petrov,

A.

M.Pilan, A.M.Popov, E.A.Rotov, I.K.Sedlyarov, A.G.Tribendis, V.N.Volkov (Budker Institute of Nuclear Physics, Novosibirsk, Russia) Feedback system for damping of longitudinal bunch oscillations in VEPP-4 collider.

In order to luminosity increase in VEPP-4 collider at BINP, it was acceded to increase the current in four-bunch mode (2 -2 +) from 5 up to 30 in each bunch. One of the problems on the way to current increase is instability associated with longitudinal bunch oscillations. A feedback system is being developed for bunch oscillations control. The feedback system consists of two identical parts, each works with separate amplifier of 100 W and deals with only one type of particles. Each part contains two channels: one for damping of inphase oscillations, another for damping of antiphase oscillations. Decrement due to the feedback system is about 3000 1/s, that exceeds the decrement due to radiating

losses approximately by 180 times.

# Evgeny Rotov: Rotov@inp.nsk.su

# P.26. V.G.Kurakin (Lebedev Physical Institute, Moscow, Russia)

Coupling Strength and Cavity Detuning Calculations for the rf Resona- tor Excited Over an Aperture

Bubnov-Galerkin method is used to calculate the coupling strength and cavity detuning for an rf cavity that is connected to a rf waveguide over a rectangular aperture in cavity surface. Both these so call external parameters are of a value in order to develop properly accelerating system of an accelerator, microton for example. In this method, electrical fields on coupling aperture surfaces are approximated by finite sums coordinate functions and expansion coefficients are founded out by appropriate procedure of join of solution of neighboring regions. In Bubnov-Galerkin method, this procedure provides energy flow continuity while crossing coupling surfaces, and this provides fast convergence of appro- priate infinite sums. Appropriate expressions for aperture conductances are derived, fol- lowed by numeric calculations. Waveguide standing wave ratios as well as cavity detuning are represented as functions of conductances mentioned.

Dr. Vyacheslav Grigoryevich Kurakin: kurakin@x4u.lebedev.ru

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