Radiation Hardening of LED Luminaires for Accelerator Tunnels

TL;DR

This paper reports on the development and testing of radiation-hardened LED emergency luminaires for CERN's underground accelerator tunnels, including a new power converter design and irradiation testing up to 100 kGy.

Contribution

It introduces a diode bridge based AC/DC power converter for LED luminaires and provides a radiation-hardened reference design under open hardware license.

Findings

Luminaires irradiated up to 100 kGy show promising performance.

Modified luminaires meet IEC 60598-2-22 compliance after hardening.

Open hardware design encourages manufacturer adoption.

Abstract

This paper summarises progress made towards the radiation hardening of LED emergency luminaires for evacuation and emergency response within the underground areas of the CERN accelerator complex. The objective has been to radiation harden existing Commercial Off-The-Shelf (COTS) emergency luminaires to maximise lighting performance, without compromising IEC 60598-2-22 compliance. A systems level approach has been adopted, leading to the development of a diode bridge based AC/DC power converter. Modified COTS luminaires including this converter design have been irradiated (to 100 kGy TID using a Cobalt-60 source), with results of a subsequent photometric analysis presented. Following encouraging tests results, a reference design for the power converter has been released under the CERN Open Hardware License to encourage manufacturer adoption. The paper concludes with areas of interest for future research in further improving the radiation hardness of LED emergency lighting for accelerators with detailed studies at the component level for high power white LED devices and associated optical components.