ANL, Argonne, Illinois, USA
The APS Upgrade of a multi-bend achromat (MBA) storage ring requires a fast bipolar power supply for the fast correction magnets. The key performance requirement of the power supply includes a small-signal bandwidth of 10 kHz for the output current. This requirement presents a challenge to the design because of the high inductance of the magnet load and a limited input DC voltage. A prototype DC/DC power supply utilizing a MOSFET H-bridge circuit with a 500 kHz PWM has been developed and tested successfully. The prototype achieved a 10-kHz bandwidth with less than 3-dB attenuation for a signal 0.5% of the maximum operating current of 15 amperes. This paper presents the design of the power circuit, the PWM method, the control loop, and the test results.
Fermilab, Batavia, Illinois, USA
Green Mountain Radio Research, Boone, USA
GMRR has developed solid-state RF-power modules that deliver up to 650 W at frequencies from 325 to 704 MHz. The nominal output of 500 W is delivered with an overall efficiency from 79% at 704 MHz to 83% percent at 325 MHz. In contrast to conventional solid-state power amplifiers, high efficiency is maintained over a wide range of output powers; e.g., 70 percent or better for outputs of 30 W or higher. Each 500-W module contains five 120-W RF power amplifiers (PAs) and a Gysel* splitter and combiner. The class-F** PAs employ GaN FETs and produce over 120 W with efficiencies from 82-86%. A class-S modulator maintains high efficiency over nearly the entire range of amplitudes. Supporting hardware includes a control computer, DSP, low-level RF amplifiers, and drivers. The 500-W modules are intended to be building blocks of a multi-kW RF power source. A system based these modules will consume 1/3 to 1/2 of the prime power required by a system based upon klystrons or conventional solid-state amplifiers and will have significantly lower cooling requirements.
* U. H. Gysel, Int. Microwave Symp. Digest, May 12 - 14, 1975.
** F. H. Raab et al., IEEE Trans. Microwave Theory Tech., March 2002.
RadiaBeam Systems, Santa Monica, California, USA
RadiaBeam, Santa Monica, California, USA
UC Davis, Davis, USA
Sierra Nevada Corporation, Irvine, USA
JLAB upgrade program requires a ~8 kW, 1497 MHz amplifier operating at more than 55-60% efficiency, and 8 kW CW power to replace up to 340 klystrons. One of possibilities for the klystron replacement is usage of high electron mobility packaged GaN transistors applied in array of highly efficient amplifiers using precise in-phase, low-loss combiners-dividers. Design features and challenges related to amplifier modules and radial multi-way dividers/combiners are discussed including HFSS simulations and measurements.
Diversified Technologies, Inc., Bedford, Massachusetts, USA
Diversified Technologies, Inc. (DTI) has designed, built, and demonstrated a prototype pulse amplifier for stripline kicker service capable of less than 5 ns rise and fall times, 5 to 90 ns pulse lengths, peak power greater than 13.7 MW at pulse repetition rates exceeding 100 kHz, and measured jitter under 100 ps. The resulting pulse is precise and repeatable, and will be of great interest to accelerator facilities requiring electromagnetic kickers. The pulse generator is based on the original specifications for the NGLS fast deflector. DTI's planar inductive adder configuration uses compensated-silicon power transistors in low inductance leadless packages with a novel charge-pump gate drive to achieve unmatched performance. The unit was brought to LBNL, compared with other researcher's efforts, and was judged very favorably. A number of development prototypes have been constructed and tested, including a successful 18.7 kV, 749 A unit. The modularity of this design will enable configuration of systems to a wide range of potential applications in both kickers and other high speed requirements, including high performance radars, directed energy systems, and excimer lasers.
IBS, Daejeon, Republic of Korea