EHT pulse generators are designed to provide precision control over the output waveform to enable process optimization. These units have an isolated/floating output and can be biased with respect to the load or grounded. They have been designed to drive plasma loads for medical devices, basic research, and semiconductor processing.
The duty cycle, output voltage, and pulse repetition frequency can each be independently adjusted by the user from zero to their max. Isolated/floating output can be biased with respect to the load.
The user specifies required characteristics based upon application need. A build scenario could be:
rise and fall time 100 ns to 1 µs, depending on load
maximum output voltages 1 kV, 2.5 kV, 5 kV or 10 kV
maximum power 100 W, 500 W, 1000 W, 5000 W
frequency DC 100 kHz (a higher burst frequency is available), and
duty cycle 0% to 100%
The unit is delivered as a turnkey system and can be operated from the front panel, or by remote control. Current source only, or source-and-sink, options are available.
Duty cycle, pulse repetition frequency, and output voltage are all independently, user adjustable from zero to maximum value. Maximum output voltage and power are set at time of order. Please contact Sky Blue to discuss your application’s specific needs.
High Voltage Modulators
EHT modulators are designed to generate precision high voltage pulses for tube and grid driving applications. These units can respond to changing load on fast timescales (< 10 µs). They are unique in that they require low voltage inputs (< 1 kV) to produce high voltage outputs.
EHT power systems have been used for neutral beam injection systems, klystron driving, and other high power RF tube driving.
EHT also designs pulser generators to your specifications.
Sample specifications are shown below. These units can be customized.
Neutral Beam Power System
Input Voltage: 0 – 700 V
Output Voltage: 0 – 15 kV
Output Current: 0 – 40 A
Arc/Open System Shutdown Time: 3 µs
Pulse Repetition Frequency: 125 kHz
Allowable Duty Cycle: 5 – 42% where 50% is 4 µs of the 8 µs total period
Pulse Width: 8 µs – 100 ms
Shot Frequency: One per minute (0.016 Hz)
Control: External Fiber Control
Waveform of Neutral Beam Power System:15 kV for 7.5 ms pulse.Waveform of Neutral Beam Power System: Fast modulation of grid voltage. Voltage increases from 7.5 kV to 15 kV in 20 µs. Overshoot can be eliminated by changing switching duty cycle in real time.
50 kV Klystron Driver
Output voltage: 50 kV, with ripple less than or equal to ±1%
Output current: 12 A
Rise time: 600 µs
Fall time: 30 µs
Pulse length: 10 s every 10 min
Fault mitigation: less than 10 J of energy delivered to the klystron in the event of a fault
Waveform of 50 kV Klystron Driver: 50 kV output pulse with less than 1% ripple.
High Voltage Switch Module
EHT High Voltage Switch (HVS) Modules consist of a series and/or parallel arrangement of solid-state switches with integrated fiber optic trigger, precision gate drive, and fast energy storage. Using an EHT HVS module eliminates the challenges typically associated with series stacking including voltage sharing, thermal balancing, triggering. This allows the user to focus on power system development.
Low Current HVS (< 200 A)
Easily stacked in series for higher voltage operation
Fiber optically isolated gate power for fast switching
Built-in overcurrent and overvoltage protection
Optional corona bars for higher voltage stacks
Optional heat sinking for continuous high-power operation
Specifications
Max operating voltage: 10 kV
Max operating current (pulse width dependent): 200 A at 5μs
Rise time: 70 ns
Adjustable pulse width - flattop depends on capacitor bank
Adjustable pulse repetition frequency - depends on included thermal management
High Current HVS (< 1 kA)
Easily stacked in series for higher voltage operation
Fiber optically isolated gate power for fast switching
Built-in overcurrent and overvoltage protection
Optional corona bars for higher voltage stacks
Optional heat sinking for continuous high-power operation
Specifications
Max operating voltage: 10 kV
Typical operating current (pulse width dependent): 1 kA at 10 μs
Rise time: 70 ns
Adjustable pulse width - flattop depends on capacitor bank
Adjustable pulse repetition frequency - depends on included thermal management
40 kV Pulsed Power System
40 kV pulses with floating output centered around ground
Pulse width: 0.6 – 10 μs
Maximum nominal current: 800 A
Output peak power: 32 MW
AC input voltage: 120 VAC (each rack)
Pulse repetition frequency: once per two minutes
Arc Pulse Width Modulation | Arc Modulation Power System
Using the Integrated Power Module (IPM), which is a high current solid-state switch, and high voltage nanosecond pulsers, EHT developed a solid-state system to initiate, drive, and modulate an arc. By decoupling the high voltage pulse required to initiate breakdown and the high current required to sustain the arc, each component can be controlled and optimized individually.
Waveform for an NSP-driven pseudospark. Load voltage (yellow) and current (green) for an arc and a 1 pF voltage divider.
The EHT NSP (20 kV, 120 W) has been previously used for generating pseudosparks and initiating discharges. Using a 1 pF voltage divider and current monitor, the load voltage and current were measured. The waveform shows the voltage (yellow) reaching a peak before the discharge occurs and current (green) begins to flow. Once current starts flowing, the voltage across the electrodes collapses, and the current is constant for the duration of the pulse. In this example, the current output of the NSP was resistively limited to about 30 A. For higher current applications, the NSP can be combined with the EHT IPM, which can drive higher currents in the arc for longer duration pulses.
Circuit diagram of pulsed-power system showing simplified NSP and IPM.
The NSP and IPM were integrated into a system that can be connected to the electrode. The circuit diagram is shown above. This figure shows a simplified version of the NSP and IPM without many of their components, but the basic concept is illustrated. Diodes D1 and D3 will need to be constructed. These diodes prevent the NSP from driving the IPM and vice versa.
Waveforms for air gap arc: Vce (yellow) and load current (magenta) with 800 V charge and peak current of 700 A. PWM parameters: 2.2 MHz, 310 ns pulses (70% duty cycle).
The arc was initiated with the high voltage of the NSP and sustained with the high current of the IPM. The figure shows the voltage across the solid-state switch in the IPM (yellow) and current in the load (magenta). At a IPM charge voltage of 800 V, 700 A was pulse width modulated (PWM) at 2.2 MHz in the plasma load at 70% duty cycle. In this system, an inductor (~500 nH) was added between the IPM and D3 to minimize the current ripple. This had the additional effect of slowing down the current rise out of the IPM to ~4 μs. Alternatively, the IPM could be triggered before the NSP. No current will flow until the arc is triggered by the EHT NSP. This system could be burst at 100 Hz – 1 kHz.
Unipolar Arbitrary Pulsers (below 10 kV)
Isolated/floating output can be biased with respect to the load
Arbitrary square wave generation
Clean square wave output with fast rise/fall times
Turnkey system with front panel and/or remote pulse control
Independently user adjustable output voltage, duty cycle, and pulse repetition frequency
Drives a wide variety of loads, including plasma discharges
Pre-Pulse reduces ringing on loads with stray inductance/capacitance
Specifications
Frequency: DC – 100 kHz (higher burst frequency possible)
Maximum output voltage options: 1, 2.5, 5, or 10 kV
Maximum power options: 100, 500, 1000, or 5000 W
Current source only or source & sink options available
Waveform of Unipolar Arbitrary Pulser (below 10 kV): isolated output produces a wide range of pulse parameters with a single pulser – 1 kV, 5 μs, 100 kHz into 6 kΩ.Waveform of Unipolar Arbitrary Pulser (below 10 kV): Pre-Pulse technology off – 50 Ω load, 10 µH of inductance, and 10 nF capacitance.Waveform of Unipolar Arbitrary Pulser (below 10 kV): Pre-Pulse technology on – 50 Ω load, 10 µH of inductance, and 10 nF capacitance.
Unipolar Arbitrary Pulsers (above 10 kV)
Isolated/floating output can be biased with respect to the load
Arbitrary square wave generation
Clean square wave output at high voltage
Turnkey system with front panel and/or remote pulse control
Independently user adjustable output voltage, duty cycle, and pulse repetition frequency
Drives a wide variety of loads, including plasma discharges
Specifications
Maximum output voltage options: 10 – 40 kV
Maximum power options: 100, 500, 1000, or 5000 W
Max Frequency: 1 kHz (higher burst frequency possible)
Maximum output voltage options: 1, 2.5, 5, or 10 kV
Maximum power options: 100, 500, 1000, or 5000 W
Waveform of Bipolar Pulser: bipolar 2 μs pulses with floating output – 2 kV into 6 kΩ at 70 kHz.Waveform of Bipolar Pulser: bipolar 2 μs pulses with floating output– 6 kV into 2.5 kΩ at 100 kHz.
Isolated Pulse Generator IPG-1000: adjustable output voltage 1 – 10 kV.Arbitrary Pulse Generator APG-1500-30-P: clean square wave output with fast rise/fall times.50 kV Klystron Driver with ripple less than or equal to ±1%.EHT High Voltage Switch (HVS): Low Current (< 200 A), High Current (< 1 kA). EHT 40 kV Pulsed Power System with floating output centered around ground
