PVX-4000-2kV-EX Pulsed Voltage Source

1. Description

The PVX-4000-2kV-EX is an air-cooled pulse generator that produces high-voltage waveforms. Optimized for high-impedance capacitive loads, it is well suited for driving extraction grids and deflection plates for electrostatic modulation of particle beams in time-of-flight mass spectrometers and accelerators. Unlike the standard PVX-4000-2kV, it carries no internal HV power supplies of its own — the output voltage is set by customer-supplied external HV DC sources connected to the rear-panel + HV Input and − HV Input connectors, from 0 V to ±2000 V. For example, a +1000 V supply on the positive input and a −1000 V supply on the negative input gives a 2000 V total. The positive and negative inputs must not exceed 2000 V total: V_positive + |V_negative| ≤ 2000 V. It is the customer’s responsibility to verify the external HV power supplies do not exceed this total.

The system supports duty cycles from 2% to 98% and repetition rates from 40 Hz to 30,000 Hz using the internal trigger — the same range as the standard unit. Because it is not limited by an internal HV supply, the external trigger reaches a much higher ceiling: single-shot to 600 kHz, with a pulse width of 500 ns to 100% duty cycle. Front-panel BNC connectors allow the unit to be externally gated and synchronized (both 50 Ω); the sync output is synchronized to the leading edge of the output pulse and is active with either the internal or external trigger.

The PVX-4000-2kV-EX has a pulse generator built in, providing a test system that can be programmed from the front-panel LCD controls or a computer interface (RS-232 and USB). When the frequency changes, the duty cycle is maintained and the displayed pulse width updates accordingly — change the frequency before the pulse width. Up to five user configurations are stored in nonvolatile memory (location 1 holds the power-up defaults), and analog voltage monitors are provided for observing the load voltage on an oscilloscope.

See also the standard PVX-4000-2kV, which carries its own internal HV supplies for standalone bench use and covers external-gate rates to 100 kHz.

2. Safety

Always refer to the Safe Operating Area (SOA) of the PVX-4000-2kV-EX, located in the datasheet. Do not open the cover — there are no user-serviceable parts inside and opening it exposes you to shock and voids the warranty. Do not install, handle, or remove the output cables or load while the unit is operating, and allow at least 10 minutes after power-down before handling the output cable or load. Allow sufficient space for air circulation, and do not use where liquids are present or in corrosive environments; clean by wiping with a dry or damp cloth.

3. Front Panel Features

4. Rear Panel Features

Accessories included: a NEMA C14 power cord, a 2-meter pulsed output cable, and 2-meter DC voltage input cables (all PCA-9400) connecting the unit to the customer-supplied HV power supplies. Each factory cable adds 1.57 pF per 1.0 cm to the total load — include this in load calculations. If only one HV polarity is used, short the unused input connector to chassis so it is not left floating.

5. Operating Considerations

Output cabling. The PVX-4000-2kV-EX drives capacitive loads; because output current is limited, smaller load capacitance gives faster rise time. Use the shortest cable possible for the fastest rise times and best pulse fidelity. The unit was tested driving a 344 pF load at 2000 V (a 56 pF capacitor at the end of 2 m of coaxial cable with 1.57 pF/cm).

Pulse voltages. The unit is rated at a maximum output of ±2000 VDC; never exceed the ±2000 V DC maximum input voltage from the customer-supplied high-voltage power supplies. Trigger method. Use either the internal trigger source or an external gate to trigger the output pulse.

6. Local Operation

Local mode is selected automatically at power-up, allowing configuration through the front-panel display and encoder: set the trigger mode (internal or external), frequency, and pulse width; save or load configurations; enable/disable the output; reset faults; and view port settings and system status (temperature). Unlike the standard unit, output voltage is not set from the front panel — it is set directly on the customer-supplied external HV power supplies.

Setup. Press Enable to disable the output. With the unit off for at least ten minutes, connect the customer-supplied high-voltage power supplies to the positive and negative HV input connectors (verify polarity — the center pin is high voltage, the housing is the return). If only one polarity is used, ground the other input connector so it is not left floating — for example, a positive-only supply at +1010 V still requires the negative input shorted to itself or to chassis. Connect the output to the load (verify polarity), make any External Trigger, Sync, or VMON connections, connect the Enable shorting connector (or a connection under 1000 Ω), and connect AC support power.

Power up. Turn on the rear power switch; the Power LED lights and the Fault LED blinks while the unit boots (~3 seconds). If there are no faults, the Fault LED turns off; a steady Fault LED indicates an error.

Set output voltage. Set the positive high-voltage power supply for the load up to +2000 V, and the negative high-voltage power supply up to −2000 V, keeping V_positive + |V_negative| ≤ 2000 V total — for example, a positive supply at +1990 V leaves only −10 V of headroom on the negative side. Set trigger, frequency, and pulse width on their respective front-panel screens (internal frequency 40 Hz–30 kHz; pulse width 2%–98% duty). When the frequency changes the duty cycle is maintained, so set frequency before pulse width.

Enable and power down. With no faults and the Enable BNC shorted (<1000 Ω), enable the external high-voltage power supplies, then press Enable on the front panel (hold up to 2 seconds) — the green LED lights and the unit sends high-voltage pulses. To power down, press Enable to disable, turn off any external trigger, disable and power off the external HV supplies, and switch off the rear power. Use the Save/Restore Settings screens to store or recall memory locations 1–5.

7. Remote Operation

A host PC can control the PVX-4000-2kV-EX through its RS-232 and USB interfaces. Any communication on the USB port disables the RS-232 port until the unit is power-cycled (RS-232 is active by default). Serial parameters are 115,200 baud, 8 data bits, no parity, 1 stop bit, no flow control, with the ASCII newline as the end-of-packet character. The command set is based on SCPI; commands and queries must be in all capital letters, with a space before any data. The unit returns a response for every command — wait for it before sending the next. Any change typically needs less than 200 ms.

8. Command List

Because output voltage is set directly on the external HV power supplies, this model has no VOLT:POSITIVE / VOLT:NEGATIVE commands.

9. Fault Codes

10. Warranty & Service

Warranty is 1 Year standard, unless otherwise specified. Materials and workmanship, return to manufacturer included. The warranty does not apply to any product repaired or altered by unauthorized persons, subjected to misuse, neglect, or accident, or used other than in accordance with furnished instructions. Returns must be preauthorized and accompanied by a return-authorization number.

Factory service and support. Berkeley Nucleonics Corporation, 2955 Kerner Blvd., San Rafael, CA 94901. Phone: (415) 453-9955. Email: operations@berkeleynucleonics.com. Web: www.berkeleynucleonics.com.