First Point Scientific - advanced concepts and their applications in the areas of plasma physics, particle beam technology, pulsed power, and electronics.

Solid-State Pulse Modulators

First Point Scientific's patented Advanced Solid-state Modulator (ASM) technology is unique in its capabilities to deliver high voltage, high current pulses over a wide range of pulse waveforms and pulse repetition frequencies.

The Technology: FPSI has developed a new class of solid-state pulse modulator based on the company’s patented Miniature Inductive Adder (MIA) topology. These systems are designed primarily for applications requiring high power modulators with a high degree of waveform control. The MIA topology arrays solid-state control elements; in parallel using electrostatic coupling and in series using electromagnetic coupling, to achieve high current and high voltage capability.

FPSI is actively working in three areas of MIA development, pulse modulators, linear amplifiers and hybrid systems, each of which is discussed below. FPSI has developed a number of MIA systems, for both experimental and commercial applications, that demonstrate this topology over a wide range of pulse parameters. Based on our extensive experience, we believe that next generation pulse modulator or linear amplifier systems can be constructed that would greatly extend any of the pulse parameters demonstrated to date.

1. Pulse Modulators: The pulse modulators produce a “square” pulse of fixed duration in the range of 100 ns to a few microseconds with a pulse repetition frequency (prf) from single-shot to >20 kHz. The systems built to date have ranged in output voltage from less than 2 kV to over 50 kV, with typical currents on the order of 0.1 kA and pulse rise and fall times in the range of 20 to 50 ns. The pictured system was designed for use in air pollution control, to power a corona discharge reactor. The output of this modulator is 50 kV, 200 A pulses of 100 ns duration, applied at 1 kHz prf.

2. Linear Amplifiers: The linear amplifiers are designed for applications requiring precise, arbitrarily shaped waveforms and can accommodate uses that demand changes in the pulse shape from pulse-to-pulse. To date, systems have been developed to produce waveforms from 100 ns to 6 µs duration, voltage ranging from 1.5 kV to 15 kV (with a 20 kV unit under construction), load current from 0.1 kA to 0.5 kA and prf to >60 kHz. The system shown below was developed to drive an ion accelerator induction cell for beam bunching with a waveform that ramped linearly from –15 kV to + 15 kV, initially in 4 µs, but in increasingly shorter pulses as the beam compression proceeds, to a final pulse length of 100 ns. The performance demonstration for this system was a 50 pulse burst at 200 kHz prf.

3. Hybrid Systems: The fidelity of many pulse power systems is limited, because cost limitations restrict the level of sophistication that can be incorporated into those systems, even though the processes into which they are incorporated would benefit from an improved waveform. To enhance these systems, FPSI has developed the Closed-loop Amplifier Regulated Driver (CARD) topology. These hybrid systems combine a low cost modulator, which provides the bulk of the required pulse energy, with a linear amplifier MIA that provides corrections to the waveforms generated by the low cost modulator. As the power requirements for the MIA are relatively small, it is a small cost increment to the overall system. A demonstration system is under development that will generate triangular pulses ±200 kV and 300 ns in duration, to provide longitudinal phase-space matching to the ion beam in the HCX experiment at Lawrence Berkeley National Laboratory.

ACKNOWLEDGEMENT: This work was supported in part by the U.S. DOE under contract No. DE-FG03-96ER82172. This support does not constitute an endorsement by DOE of the views expressed herein.

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