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.
| 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 |
| 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 |
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.