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Radiation Tolerant LED Luminaire

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Last edited by James Devine
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Radiation Tolerant LED Luminaire

Project status: In production.

Following on from work done on a radiation resistant power supply for emergency lights, a new design has been developed to cope with the higher power demands of conventional lighting in radioactive environments.
The LED luminaire is designed to be equivalent to the 58W T8 fluorescent tube with the following performance objectives:

  • Smaller physical size than an equivalent T8 luminaire to facilitate retro-fit
  • Equivalent or higher light output (>2500lm)
  • CRI >= 72
  • Lamp Life > 50,000 hours to 50% failures

image

Sample luminaire installed in the CERN PS accelerator tunnel, April 2019.

Research basis

The development of radiation hard lighting for the CERN accelerator complex started in 2009 with some initial tests on emergency luminaires. Since then the growing trend towards LED and the increasing emphasis on energy efficiency in EU directives has accelerated the obsolescence of conventional T8 fluorescent luminaires with wirewound ballasts (which, by virtue of the lack of electronic components are intrinsically very radiation hard). As a result CERN has been developing modifications to conventional LED luminaire designs which allow operation in the radioactive environment found in the accelerator tunnels.

A summary of the work on emergency lighting can be found here:

Radiation Hardening of LED Luminaires for Accelerator Tunnels

Modelling of proton irradiated GaN-based high-power white light-emitting diodes

Radiation testing of Optical and Semiconductor components for Radiation-Tolerant LED luminaires

High-energy proton irradiation effects on GaN hybrid-drain-embedded gate injection transistors

Forthcoming publication: Proton irradiation of GaN transistor based power supply operating in the linear region (RADECS 2020).

Test data from online testing (supply energised during irradiation) is still ongoing. The circuit below shows the variation used for the online tests, where a valley fill circuit has been added to reduce harmonics from the power supply. testbench_circuit

Functional specifications for electronic components

Technical Specification:

High Radiation areas - Linear Power Supply Module for LED lighting

Variant 3 electrical schematic
Variant 3 bill of materials

NB Panasonic have stopped GaN device production as of 2020/21, the Infineon IGT60R190 is a replacement part for the transistors, with an alternative footprint but "virtually identical" internal performance.

  • Input Voltage: 230V AC RMS, between phase and neutral
  • Single-phase bridge rectifier topology
  • Output voltage: 320V DC
  • 4x SiC (silicon carbide) Schottky diodes ST STPSC10H12G-TR
  • Maximum blocking voltage: 1200 V
  • Diodes radiation tested in IRRAD, up to 2×10^14 p/cm2.
  • 2x GaN Gate Injection Transistors (Panasonic PGA26E019BA / PGA26E07BA or Infineon IGT60R190)
  • GaN Gate Injection Transistors irradiation results (IRRAD) to be released soon.
  • LED string current is controlled below 400mA
  • Voltage Tolerance: +/-10%
  • Input Frequency: 50Hz
  • Frequency Tolerance: +/- 0.5Hz
  • Maximum electrical power: 65 W (measured at input terminals)
  • Earthing Regime: TN
  • Filters to be implemented in production versions on both AC and DC sides
  • Relevant standards to be observed: IEC 61000-3-2, EN 55015, EN 50082-1, EN 50082-2 (to be applied by manufacturer)

LED module (1 unit per luminaire)

  • 100x LED Osram Oslon Square GW CSSRM2.PM connected in series
  • Average DC current in our luminaire (~100 mA)
  • Typical voltage drop on LED at 100 mA: 2.7 V
  • Luminous flux (per LED) at 100 mA: ~50 lm
  • Luminous flux (per board) at 100 mA: ~5000 lm
  • Tested against radiation in IRRAD, up to 2×10^14 p/cm2.
  • 50% reduction in light output: ~10 kGy (expected >10 year lifetime in typical CERN SPS radiation environment)

The design specifically excludes a transformer in order to minimise activation of the luminaire, however significant line filtering (inductors) should be added to the design in order to meet local EMC standards (IEC etc.).

Spice simulations are provided for the electronics model.

General specifications for the luminaire construction

Project information

The design files are in LTSpice format, including the schematic and simulated electrical performance. You will need LTSpice to open the individual designs, and in some cases additional component libraries from the component manufacturers will be required.

Contacts

Commercial producers

  • Two suppliers are currently manufacturing these products under contract for CERN: Thorlux (External link) Isocom (External link)

Project Development

  • James Devine - CERN - General question about project
  • Alessandro Floriduz - CERN - Fellow (2016-2018)
  • Eva Cano Gonzalez - CERN - Fellow (2018 - )

Project Status

Date Event
02-10-2017 Completion of irradiation test campaign for LED and SIC diodes
29-01-2018 Successful circuit test of Variant 1 design
07-06-2018 Successful circuit test of Variant 2 design
14-09-2018 Successful circuit test of Variant 3 design
19-11-2018 Tender launched for industrial production of 200 luminaires
19-12-2018 Contracts awarded, start of design phase
19-06-2019 Online radiation testing of prototypes conducted at KVI Kart facility, NL
01-10-2020 First CERN installation completed in the PS and TT2 accelerator tunnels

J Devine - 03 July 2019

Files