High-Voltage Test & Detector Biasing
Two very different jobs share the same requirement: a clean, stable DC high voltage that does exactly what it is set to do. The first job is test. High-voltage component testing and semiconductor characterization apply a known voltage and read a small response, so any noise or drift in the source shows up directly in the measurement. The second job is biasing. Photomultiplier tubes, solid-state and gas detectors, and accelerator electrodes need a bias that holds steady, because the gain of a PMT and the field at an electrode depend on it. In both cases the supply is part of the instrument, and its ripple and stability set the floor on what the rest of the system can achieve.
Berkeley Nucleonics, through its Directed Energy Division, supplies high-voltage DC across a wide span, from the bias rails detectors live on up to hundreds of kilovolts for high-voltage test, with the regulation and protection these applications demand.
The challenge
The defining requirement is a quiet, steady output. In a detector, ripple on the bias rail rides straight through to the signal, so a PMT or a semiconductor detector reading low-level events needs a bias with ripple measured in parts per million, not percent. In a test setup, drift is just as damaging as ripple: a characterization that takes minutes is worthless if the applied voltage wanders during the sweep, so the source has to hold its setpoint against time, temperature, and changing load. Reaching very high voltage, into the hundreds of kilovolts, only sharpens these demands, because the same fractional ripple is a much larger absolute disturbance.
Protection is the other half of the problem. High-voltage test exists to find the point where something breaks down, which means the supply will face arcs, flashovers, and dead shorts as a normal part of the work. It has to survive a short circuit without damage and respond cleanly, and where a load can store or return energy it has to tolerate reverse voltage rather than fail. And because these supplies sit inside automated benches, they need clean analog control so a test executive can program the voltage and read it back as part of a sequence.
The BNC approach
The DEI high-voltage supplies are built for regulation first. The PNC-Series delivers DC high voltage up to 300 kV with tight regulation, and the high-precision PNChp variant reaches ripple on the order of 10 ppm, which is the class of stability a sensitive detector or a precision characterization bench needs. Low ripple and low drift are treated as the headline specification rather than a footnote, because for these applications they are the whole point of the instrument.
Stability is what separates a usable bias from a noisy one. A photomultiplier gain rises steeply with applied voltage, so a small wander on the rail turns into a larger wander in gain, and any drift over the course of a long count smears the result. Holding the output to a tight fraction of a percent over time, temperature, and load is therefore not a luxury, it is the condition that lets a detector hold its calibration across a shift. The same stability serves a characterization sweep, where the value of the measurement rests on the applied voltage being exactly what the instrument reported when each point was taken.
Protection is designed in. The supplies are built to handle the short-circuit and flashover events that high-voltage test produces as routine occurrences, and to tolerate reverse voltage where the load can return energy, so the failure of a device under test does not become the failure of the source driving it. Analog control lets the supply sit naturally inside an automated bench, with the voltage programmed and monitored as part of a test sequence rather than set by hand. Where an application needs high current alongside high voltage, the PTN-Series covers the high-current regulated case, so a lab can pick the member of the family that matches its load. These ripple, voltage, and current figures are model capabilities; confirm them against the current published datasheet for your exact variant.
Recommended instruments
Choose by what the load demands: maximum voltage, the ripple and stability your measurement can tolerate, and whether the application also needs significant current.
- PNC-Series: DC high voltage to 300 kV, with the high-precision PNChp variant reaching roughly 10 ppm ripple for sensitive detector biasing and precision high-voltage test.
Getting started
Start from the load. Fix the maximum voltage you need to reach, then the ripple and stability your measurement or your detector can tolerate, and decide how much current the load draws at that voltage. Account for the fault behavior you expect, whether arcs in a test setup or stored energy in a biased load, and confirm the analog control interface fits your bench automation. Talk to a BNC applications engineer at info@berkeleynucleonics.com or 800-234-7858 to match a supply to your test or biasing requirement.