Speaker
Description
Summary
Following a process of proof-of-concept on the requirements for radiation and
magnetic field tolerant low-voltage power supplies to be used to power silicon
detectors in LHC experiments, a common procurement action was undertaken by the
experiments and PH-ESS group. Rather than making a custom design matching the
electrical requirements and robust enough to work in their specific environments in
term of magnetic field and radiations, it has been decided to select COTS devices
following the electrical specifications, test them and adjust their design together
with the manufacturer, to make them tolerant to magnetic field and radiations.
Based on the requirements of the all four LHC experiments for regulated low voltage
DC power supplies, a market survey for COTS devices was thus launched. A common
technical specification was established to fulfil all these requirements:
electrical, tolerance to magnetic field and radiations.
Following the market survey, two main manufacturers were selected and their
equipments were evaluated.
First of all, electrical tests were performed to ensure their compliancy to the
initial requirements. Several parameters were checked, such as static and dynamic
regulation, ripple, efficiency, overcurrent and overvoltage protection and
stability. To perform this, an in house test set up was implemented. Moreover,
electromagnetic compatibility tests were performed in order to verify the harmonic
rejection and the power factor.
The tolerance to magnetic field of these power supplies was then evaluated. The part
of the power supply or converter intended to be magnetic field tolerant was
subjected to a functional test whilst being exposed to a quoted magnetic field in a
calibrated, large aperture electromagnet. The test was repeated in three axes in
order to check the sensitive components in the worst condition.
Finally, CERN/PH/ESS group in collaboration with LHC experiments have organized
radiation campaigns. Many tests were performed using low energy neutrons to analyze
possible displacement damage (NIEL) of the control electronics and proton beam to
study Single Event Effects (SEE).
If the equipments were matching most of the specifications (specifically in term of
electrical parameters and tolerance to magnetic field), the tolerance to radiations
was limited and required some parts of the power supplies to be redesigned in
collaboration with the manufacturers.
The process of the evaluation and testing of these advanced COTS radiation and
magnetic field tolerant low-voltage power supplies will be described. An overview of
the design principles of the power supplies will be given together with the test
methods used and results obtained.
