Since long, Nikhef has developed high voltage supplies for
photo-multiplier tubes, to be used at various experiments in high
energy physics (ACCMOR, ZEUS
and Antares). These
supplies were dedicated to supply low output currents, usually
less than 1µA. They were remotely controlled by a dedicated NIM
unit, an RS232 line and a CAN bus respectively.
Because of the growing demand for dedicated high voltage power supplies
for gaseous detectors, we have started the development of a new range
of miniHV power supplies especially for this application in the
laboratory and at small scale experiments.
miniHV
miniHV is based on three components:
The Cockroft Walton circuit to generate the high voltage. It
includes a diode leakage current compensation circuit.
A local processor to control the high voltage and to monitor the
output current. Communication with the processor proceeds via a CAN
bus. Additional lines of the CAN bus are used for the supply voltage of
miniHV.
A low voltage power supply. It is also used to split the standard
DB9 CANbus to two strings
using RJ45 cables. These must be terminated by 180 ohms each.
Specifications
For the development of miniHV we aim for the following specifications:
An output voltage between -10 and -1000 V. There is no direct
feedback by a voltage divider. A bleeder resistor is included, which
takes ~5 nA at 1000 V.
The output current is monitored with a least count of 100 pA or
less, to be read out by the CAN bus. Also the bleeder current is
monitored.
The current trip is controlled by the local processor. The
trip value is set by CAN communication.
For the CAN bus we use the CANopen protocol
The ramping speed may be adjusted over the full range from fast
ramp (< 1 s) to slow ramp (~ 1 hour)
suggestions for this page to: Henk Groenstege
.
