Two-Half-Period Acceleration Scheme in a Synchrotron
Abstract Generated abstract
This paper proposes a two half-cycle acceleration system for synchrotrons intended to reduce reliance on bulky external resonators and make greater use of accelerating structures integrated into the vacuum chamber. The scheme uses two successive accelerating gaps, such as annular slots in the chamber’s conducting coating, with voltage applied alternately in each half-cycle of the radio-frequency field so that particles gain energy at both locations during one revolution. The author argues that this arrangement can double the energy gain per turn while allowing the same RF generator to feed the gaps in succession, without increasing high-frequency leakage associated with chamber capacitance. Variants involving quadrant waveguides, quarter-wave resonators, and loaded waveguides are also discussed as possible implementations for particle acceleration.
Full Text
TWO-HALF-CYCLE ACCELERATION SCHEME IN A SYNCHROTRON
A. A. VOROB'EV
(Presented by the Conference on Electron Accelerators, held in Tomsk, September 2–7, 1959.)
The resonators of the accelerating system of powerful synchrotrons are complex and bulky structures, occupying a great deal of space. To accommodate them it is necessary to separate the ring electromagnet and to arrange straight sections of the accelerating chamber. Replacing external resonators with accelerating systems built into the vacuum accelerating chamber will also make it possible to increase the operating field strength of the accelerating electric field.
It has been proposed to excite in the chamber, as in a waveguide, electromagnetic waves of the corresponding type, the azimuthal component of whose electric vector is used for accelerating charged particles. By making a gap in the conducting layer of the accelerating chamber, a high-frequency field can be excited in it [1]. Such a device was used for acceleration [2].
It is proposed to carry out acceleration in a synchrotron in two successively arranged gaps, which in the simplest case are annular slots in the layer of the conducting coating of the chamber. The voltage in one slot arises in the first half-cycle, and in the second slot in the second half-cycle of the applied alternating voltage. Excitation of the voltage is possible either according to the supply scheme for cyclotron dees (in this case the quadrants of the chamber are a variety of dees), or, as B. A. Solntsev did [2], by means of a resonant system of a simpler type. A voltage maximum arises in the accelerating slot. Acceleration of charged particles can be carried out both on the fundamental wave and on harmonics. Figure 1 presents the scheme of the acceleration system under consideration.
The advantage of an acceleration system with two gaps and successive acceleration of the particles in each of them is the doubled increase in particle energy per revolution and the possibility of feeding each accelerating gap in turn from one and the same RF generator. Since the capacitance of the acceleration system, determined by the capacitance of the conducting layer of the accelerating chamber with respect to ground, remains the same as with one gap, the leakage of high-frequency power also remains unchanged.
A section of the conducting coating laid along the length of one quadrant can also be excited as a quarter-wave reson-
resonator. In this case, a maximum voltage arises at its ungrounded end. Under the condition of excitation on the other resonator, the voltages in the accelerating gap will be in antiphase, producing a doubled voltage. Finally, if loaded waveguides are used in which the propagation velocity of the electromagnetic waves is equal to the speed of light, electron acceleration can be carried out not only in the accelerating gap, but also during their drift in the waveguide.
Fig. 1.
Excitation of the quadrant waveguides can be carried out by one of the schemes developed for accelerating successive sections of linear waveguide accelerators [3].
REFERENCES
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A. A. Vorob'ev and G. V. Krivoshekov, Izv. Tomsk Polytechnic Institute, vol. 87, 358, 1957.
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B. A. Solntsev, Izv. Tomsk Polytechnic Institute, vol. 87, 338, 1957.
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A. A. Vorob'ev, B. A. Solntsev, V. N. Titov, Izv. vuzov MVO USSR — Radio Engineering, 2, 246, 1959.
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G. A. Zeitlenok, V. V. Rumyantsev, V. L. Smirnov, L. P. Fomin, V. K. Khokhlov, I. A. Grishaev, and P. M. Zeidlits, Atomic Energy, 4, 448, 1958.