DEFLECTOR POWER SUPPLY FOR SECTOR-FOCUSED CYCLOTRONS

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Abstract
Because of the higher particle energy sector-focused cyclotrons require higher gradients in their electrostatic deflectors than ordinary cyclotrons. A higher operating gradient can be achieved by exciting the deflector from a low- energy-storage power supply that permits control of the electrode surface heating during each spark. A pair of high-frequency Cockcroft-Walton rectifiers with this capability was built for the Lawrence Radiation Laboratory's 88-Inch Cyclotron. Each rectifier consists of a six-stage circuit designed to deliver 120 kv at 5 mamp. It is driven by a 100-kc oscillator. The rectifier is built from inexpensive silicon diodes, each with a rating of 600 piV, 0.75 amp, and a storage time of 2 mu sec. The diodes are assembled on etched circuit boards. Between decks of the rectifier, 900-pf, 30-kv ceramic capacitors similar to those in television sets are used. The dc output voltage is controlled by plate modulation of the oscillator and regulated to 0.01% by an electronic regulator. The rectifier is protected against spark-induced surge currents by an electronic crowbar operating on the screen grid of the oscillator. (auth)

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