Diversified Technologies, Inc., Bedford, Massachusetts, USA
Semiconductor thyristors have long been used as a replacement for thyratrons in low power or long pulse RF systems. To date, however, such thyristor assemblies have not demonstrated the reliability needed for installation in short pulse, high peak power RF stations used with many pulsed electron accelerators. The fast rising current in a thyristor tends to be carried in a small region, rather than across the whole device, and this localized current concentration can cause a short circuit failure. An alternate solid-state device, the insulated-gate bipolar transistor (IGBT), can readily operate at the speed needed for the accelerator, but commercial IGBTs cannot handle the voltage and current required. It is, however, possible to assemble these devices in arrays to reach the required performance levels without sacrificing their inherent speed. Diversified Technologies, Inc. (DTI) has patented and refined the technology required to build these arrays of series-parallel connected switches. DTI is currently developing an affordable, reliable, form-fit-function replacement for the klystron modulator thyratrons at SLAC capable of pulsing at 360 kV, 420 A, 6μs, and 120 Hz.
Diversified Technologies, Inc., Bedford, Massachusetts, USA
Sigma Phi Electronics, Wissembourg, France
Sigmaphi, Vannes, France
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.
Muons, Inc, Illinois, USA
JLab, Newport News, Virginia, USA
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.
ANL, Argonne, Illinois, USA
LBNL, Berkeley, California, USA
To support the current research and development in APS LINAC area, the existing LINAC rf control performance needs to be much improved, and thus an upgrade of the legacy LINAC rf electronics becomes necessary. The proposed upgrade plan centers on the concept of using a modern, network-attached, rack-mount digital electronics platform 'Internet Rack Monitor-Controller (or IRMC) to replace the existing analog ones on the legacy crate/backplane-based hardware. The system model of the envisioned IRMC is basically a 3-tier stack with a high-performance processor in the mid- layer to handle the general digital signal processing (DSP). The custom FPGA IP's in the bottom layer handle the high-speed, real-time, low-latency DSP tasks, and provide the interface ports. A network communication gateway, in conjunction with an embedded event receiver (EVR), in the top layer merges the Internet Rack Monitor-Controller device into the networks of the accelerator controls infrastructure. Although the concept is very much in trend with today's Internet-of-Things (IoT), this implementation has actually been used in accelerators for over two decades.