High stress test: MOSFET dT=80°C, maximum rated junction temperature is 150°C. Thus critical ambient temperature ~70°C
Environmental validation tests:
360 power cycles per year may be critical for the RaToPUS
Requirement comes from G. Kasprowicz, but they don't use the DI/OT in radiation!
Above 375Gy power cycling the RaToPUS causes a short on the main MOSFET, however it is rather unlikely that the RaToPUS will reach the requested lifetime of 20 years even in a non-rad environment, hence the dose of 500 Gy (PIC) may be split on 2x10 years = 250 Gy if replacing after that time. Probably even less than 10 years. (The same applies to COTS PSUs)
MoniMod may also fail before 500Gy, but it’s not critical
Also temperature cycles are not considered yet which can cause degradation
Power cycles may be tested in a non-rad environment to at least validate this requirement there
The inductors of the RaToPUS cause a vibration (100 Hz) in operation.
Silicon potting can be used for components. COTS PSU do use that.
EoL Test - RaToPUS:
Justification to not do an EoL test for the RaToPUS see slides
Next steps: Consult EPC for experience and advice
Environmental Stress Screening:
Time and personpower effort:
Good experience for a 22h T-cycling, which would mean approximately 30min every morning to prepare and start the test
TBD how many DI/OT crates can be fitted into the climatic chamber. Potential interaction with humidity regulation to be taken into account
Reliability Demonstration - Run In:
Test bench is to be developped (ESS test bench to be adapted). IN could be a candidate for SW.
Test bench design:
Irradiation test setups can be reused (e.g. for RaToPUS)
Personpower will be needed to perform the tests (ESS; Run In)
Major Outcomes & Actions
Get in touch with G. Kasprowicz whether the DI/OT will be power cycled daily
Check manufacturer lifetime data of COTS PSUs
Discuss with R. Garcia Alia which headroom in terms of radiation dose (Gy) is required (PIC requirement: 25Gy/year for 20 years of lifetime)
Fan tray: Whereever possible fans should be used also in radiation areas to keep the crate temperature as low as possible, thus increasing the reliability
To be assessed if a power cycle test can/should be performed without radiation stress
Vibration test for the RaToPUS? -> Check potential acceleration model or simulate in Ansys
Assess the use of potting compound to reduce the effect of vibration from the inductors
To be checked which (degradation) parameters of the RaToPUS can be measured to be able to identify potential wear out and replace before failure. Also, modules with any monitored degradation can be replaced after some time in operation (>5 years) and then tested at accelerated conditions to determine the propagation of the degrading characteristic
Consult EPC for potential EoL tests or alternative strategies
Define load-sharing ratio for the redundant RaToPUS
Organise meeting with IN to discuss test bench (GW/SW/database) development. Also consult BI to profit from existing DB logging, GUI etc.