Summarv As a part of che manufacturing processes, several mechanical measurements are made on ISABELLE dipoles. These are done both Co control the process and co provide information for the evaluation of the behavior of the completed magnets. This paper discusses the Young's Modulus (E • 1-3 x 10° psi), the thermal contraction of the coil assembly (AL/L •-290+17 x 10~^ at 77"XJ, and the loss of applied prescress wich time (~-20* for times 20 days).
BNL 25772To investigate the performance that can be achieved for low energy heavy 1on particle acceleration, a two megahertz low beta linac Is being built. This structure, intended for acceleration of 260 keV xenon or 400 keV mercury, is comprised of a quarter wavelength parallel plate resonator used to support drift tubes forming 4 g*/2 structure. The 20 gap accelerator, to be driven by a 30 kilowatt transmitter, will provide 10 milliamperes of mercury ions at the 1.8 MeV energy level. Focussing 1s achieved by a unique arrangement of electrostatic quadruples. A plan view of the accelerating system is ?h "wn in Figure 1. I. Radio Frequency Power AmplifierThe radio frequency power amplifier is a departure from what night be considered conventional for accelerating systems.1 Instead of designing and prototyping a new system, a 20 year old, 4-to 30-MHz communications transmitter was purchased, rebuilt and modified to operate at 2 MHz. The resulting system required a minimal budget and only four months for completion.The transmitter was a typical 30 kV unmodulated unit. It consisted of five stages of which the last three operated in a saturated cla'ss C mode, and thus, fixed gain. Its output was designed for balanced loads ranging from 300 to 800 ohms.Certain modifications had to be made before it would be a useable rf system. First, interstage coupling networks had to be altered to tune to 2 MHz. Also, the final tank circuit and output matching networks were discarded and the plates of the final amplifier were coupled directly to a 3000 ohm impedance tap point on the transmission line/resonator as shown in Figure 2. Finally, additional capacitance was added to the high voltage power supply to allow for pulsed operation at nearly the peak power supply voltage with only a small droop. Mercury vapor rectifiers were retained. Since the capacitance of the equivalent shunt resonator circuit is high, 1 x 10*9 farads, the stored energy of 2.S joules at 100 kilovolts operation will ease the beam loading problem.
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