MHE - Pulse Systems Group

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Pulse Systems Group

MHE represents Pulse Systems Group (PSG), a leader in pulse power technology ranging from nanosecond to picosecond range. PSG produces several families of pulse generators in the nanosecond and picosecond range, as well as a family of high frequency pulse generators. Generators are available as specified below or according to customer specifications.

Also available from PSG are a number of novel semiconductor devices with applications in pulse power.



Nanosecond Pulse Generators

Model No. Output Voltage w/ 50 Ohm load Rise Time Pulse Width avg. PRF (burst PRF) Power Supply Special Feature Dimensions (mm) Delivery (months)
NPG-80 >80KV (w/ 100 ohm load) <0.7ns 1-2ns decay 1KHz +300DC Oil cooled 300x300x150 main block 300x300x150 heat exchanger 6
NPG-20 >20KV <0.7ns 1-2ns decay 1 KHz +5, +100, +0-300VDC   300x200x120 2
NPG-10N >10KV 1-2ns 5-10ns decay 1 KHz +50, +900-1800VDC matched w/ non-ohmic load 70x50x30 2
NPG-10-100 >10KV 0.6ns 1ns decay 100KHz +200VDC   300xx200x120 3
NPG-10-25 >10KV 0.6ns 1ns decay 25KHz +200VDC   200x140x100 3
NPG-30 >30KV <0.7ns 1-2ns decay 1.5KHz +28, +300VDC   300x200x120 3
NPG-30P >30KV <4ns 20ns 3KHz 300-500VDC or 220/380VAC avg. output power >1.5KW 300x200x200 heat exchanger 4


Picosecond Pulse Generators

Model No. Output Voltage w/ 50 Ohm load Rise Time Pulse Width avg. PRF (burst PRF) Power Supply Special Feature Dimensions (mm) Delivery (months)
PPG-20 >20KV <100ps 1.5ns decay 1KHz 110/220VAC   300x230x120 2
PPG-10-25 >10K <100ps 1ns decay 25KHZ +200VDC   200x140x100 3
PPG-2 >2KV <50ps 1-2ns decay 10KHz (200KHz) 5, 27, 200VDC or 110/220VAC   300x200x120 2
PPG-2D >2KV <100ps 0.1-1ns decay 200Hz 200Hz +5, +1,000 VDC trigger delay <30ns 50x50x30 2
PPG-2S >2KV <100ps .01-10ms step 1KHz +10, +100VDC   50x50x30 2
PPG-2SV >2KV <100ps 10-100ns flat top 1KHz +10, +100VDC fall time<5ns 50x50x30 2


High Frequency Pulse Generators

Model No. Output Voltage w/ 50 Ohm load Rise Time Pulse Width avg. PRF (burst PRF) Power Supply Special Feature Dimensions (mm) Delivery (months)
HFPG1-0.5 >500V <0.7ns 1.5-2ns decay 200KHz +50VDC avg. output power ~1W 80x60x30x2 2
HFPG1P-0.5 1P-0.5 <0.7ns 1.5-2ns decay 4MHz +50VDC avg. output power ~10W 100x60x60 4
HFPG1-2.5 >2.5KV <0.7ns 1.5-2ns decay (2MHz) +100, +200VDC   120x80x60 4
HFPG1P-2.5 >2.5KV <0.7ns 1.5-2ns decay 600KHz (2MHz) +100, +200VDC avg. power>100W (liquid cooled) 240x220x200 4
HFPG2-1 >1,000V <0.7ns <2ns decay (4MHz) +50VDC for high load (transmitting antenna) 100x60x30 4
HFPG3-0.5 >500V <5ns 10ns (4MHz) +50VDC efficiency >40% 80x60x30 2
HFPG3-0.05 >50V <0.7ns <2ns decay 25MHz +12VDC   60x40x40 2
HFPG4-0.5 >500V <100ps 0.5ns decay (200KHz) +50VDC   100x60x30 4
HFPG4-2.5 >2.5KV <100ps 0.5ns decay (200KHz) +15, +100VDC   120x80x60 4
HFPG5-0.05 >50V <100ps 0.5ns decay >20MHz +12VDC   80x40x40 2
HFPG6-25A >25A <1ns <2ns decay >1MHz +24VDC for low load (laser pump) 200x60x30 2




Novel Semiconductor Devices

by Pulse Systems Group

A Short Explanation of Advantages of Opening Switches

for Achieving Uniform Discharge in Gases

Methods of pulse generation using novel semiconductor opening switches to discharge inductively stored energy have several advantages:

1. Energy is stored in an inductor at low voltage, then the current is broken quickly by use of opening switch, such as a Drift Step Recovery Diode (DSRD). The current goes to the load forming a short pulse. The load voltage during the pulse is an order of magnitude higher than the initial voltage used to store energy in the inductor. Therefore the high voltage exists only during a very short (several nanoseconds) pulse length, and only in a very small portion of the circuit (output cable). This has obvious safety advantages, and the arcing problems are not so severe as for high voltage DC.

2. The typical discharge of a capacitor by closing switch into a load may be represented as a voltage source, i.e. if the load quickly changes its resistance the current follows the resistance, and the voltage is kept constant. When the load consists of a gas discharge gap, contraction of current (filamentation) may occur, which limits the energy pumped into the gas during the pulse.

In the case of an opening switch and inductive storage, the inductor may be represented as a current source, i.e. the system tries to keep current constant in spite of changes in the load resistance. The voltage at the load matches the changing resistance to maintain a given current, because the current pulse length is self-adjusting. In this case contraction (filamentation) may be suppressed.

Russian semiconductor scientists have tested this approach in preionization systems for power CO2 lasers. The Russian laser scientists said that for the first time in their lives they saw uniformly spreading light emission from the space between large electrode plates. This phenomenon was demonstrated just before the USSR collapsed and the work, although very promising, was postponed indefinitely due to lack of funding.

3. Gas discharge utilizing opening switches was also found to be significantly more efficient (lower power consumption) than with the closing switch approach.

In addition to preionization of lasers, this technology should find application in other gas discharge systems, such as the use of small electrostatic precipitators for cleaning diesel engine exhaust. There may also be applications for flash lamps or other kinds of gas-filled tubes.