A new 200 Mhz power amplifier system has been used operationally on the Bevatron Local Injector 20 MEV LINAC with two different power tetrodes: an EIMAC 4CW100,000E and a Thomson-Houston TH-535. The same basic anode and grid structures were used with both tubes. The system has provided increased power output over the 4616 tetrode previously used. Maximum operational gradients were achieved with both tubes. System testing, tube interchangeability, and high power operating data are presented

The Bevalac extraction time was increased from 1 to a maximum of 9.5 seconds, thus increasing the synchrotron duty factor and the data rate for experiments by a factor of 2-3, depending on the magnetic field. This slow rate of extraction required improved control of beam time structure, since magnet ripple remained approximately constant while the spill rate was decreased. Measurements of spill structure for the long spill are presented. Changes made to the accelerator systems are described, as well as tuning procedures found to be necessary, and the ultimate hardware limits found for the spill length

The Bevalac injector final stage RF amplifier systems have been successfully upgraded to reduce energy consumption and operating costs. The energy savings realized at completion of the project was primarily obtained by eliminating the filament power required for operation of the hard tube modulator (HTM) system. The HTM system was used to key the plate voltage to two tubes, a TH-515 which provides 800 kW of RF output power and a TH-516 which provides 2.4 MW. The first phase required modifying the amplifier structure to remove the ground connection to the final amplifier grid while maintaining a low impedance path for the grid-anode and grid-cathode RF circulating currents. The second phase provided a fixed source of DC grid bias for the TH-515 and a pulsed grid bias source for the TH-516. The bias voltages appropriately interlock the DC plate voltage supply to the final amplifiers. Construction, design, and operating parameters are described.<>

A 200-MHz intermediate power amplifier system, comprising of four separate chassis or cavity amplifiers is being developed as a driver stage for the Bevalac injector final RF amplifiers. The initial stage is a 200-W, solid-state, RF amplifier with 44 dB of gain. The two succeeding stages are cavity amplifiers that incorporate vacuum tubes. The first of the tube-type amplifiers is driven by the 200-W amplifier and contains a 3CPX800A7 triode calculated to output a maximum of 5 kW. The next stage, driven by the 5-kW amplifier, contains a 4CW25000B tetrode and is designed to drive the final amplifier. The 4CW25K stage is calculated to provide a maximum output power of 50 kW. The final stage is designed to operate with either a Varian 4CW100000e or a TH535 manufactured by Thomson-CSF. The final stage gain, using the 4CW100Ke, is calculated to be 13 dB at approximately 300-kW output. Using the Thomson tube, the stage gain is calculated to be slightly greater; however, the maximum achievable RF output power is approximately 300 kW. The system construction, design, and initial high power test results are presented.<>