Diversified Technologies, Inc., Bedford, Massachusetts, USA
Diversified Technologies, Inc. (DTI), under an SBIR grant from the U.S. Department of Energy, assembled a prototype MOSFET-based pulse generator capable of meeting the original specifications for the Next Generation Light Source (NGLS) fast deflector. This pulse generator is also applicable to other high repetition-rate FELs with multiplexed beamlines. The unit must drive a 50 Ω load (such as a terminated TEM deflecting structure) at 10 kV, with flat-topped pulses at a 100 kHz average rate. The specification requires a 2 ns rise time (10 – 90%), a highly repeatable flattop with pulse width from 5 – 40 ns, and a fall time (90% to .01%) less than 1 μs (to allow a 1 MHz beam pulse rate). The driver must also effectively absorb high-order mode signals emerging from the deflector itself. The solid-state pulse generator is suitable for many accelerator systems with < 10 ns kicker requirements. The performance and applications of the unit will be described.
CAEP/IAE, Mianyang, Sichuan, People's Republic of China
PSI, Villigen PSI, Switzerland
Automatic Control Laboratory, ETH Zurich, Zurich, Switzerland
An automatic procedure is developed to provide the optimal operating point of a klystron. Since klystrons are nonlinear with respect to the input amplitude, a model-based amplitude controller is introduced which uses the klystron characteristic curves to obtain the appropriate high voltage power supply and amplitude, such that the operating point is close to the saturation. An advantage of the proposed design is that the overall open-loop system (from the input to the RF station to the klystron output amplitude) is linearized. The method has been successfully tested on a full scale RF system running at nominal power.
*Ch.Rapp, Effects of HPA-Nonlinearity on a 4-DPSK/OFDM-Signal …,Euro.
Conf. on Satellite Communi.,1991. <CR>
**A.Cann, Nonlinearity Model With Variable Knee…,IEEE Trans. Aerosp. Electron. Syst.,1980
Diversified Technologies, Inc., Bedford, Massachusetts, USA
Rockfield Research Inc., Las Vegas, Nevada, USA
High voltage short-pulse klystron modulators are required for numerous X-Band accelerator designs. At the very high voltages required for these transmitters, all of the existing designs are based on pulse transformers, which significantly limits their performance and efficiency. There is not a fully optimized, transformer-less modulator design capable of meeting the demanding requirements of very peak power, short pulse RF stations. Under a U.S. Department of Energy grant, Diversified Technologies, Inc. (DTI) is developing a short pulse, solid-state Marx modulator. The modulator is designed for high efficiency in the 100 kV to 500 kV range, for currents up to 250 A, pulse lengths of 0.2 to 5.0 μs, and risetimes <300 ns. Key objectives of the development effort are modularity and scalability, combined with low cost and ease of manufacture. For short-pulse modulators, this Marx topology provides a means to achieve fast risetimes and flattop control that are not available with hard switch or transformer-coupled topologies. The system is in the final stages of testing prior to installation at Yale University.