High Current Diffusion Type Diodes at Cryogenic Temperatures for the LHC Superconducting Magnet Protection
High-current by-pass diodes are required for the protection of the superconducting magnets for the Large Hadron Collider LHC at CERN. These diodes are at liquid helium temperature and will be exposed to irradiation. With the re-location of the by-pass diodes for the main dipoles underneath the iron yoke, and of those for the quadrupoles at the bottom of the cryostat the new estimations for the irradiation dose amounts to about 30 Gy with a neutron fluence of about 1.5 × 1011 n/cm2 for the dipole diodes, and about 100 Gy and 5 × 1011 n/cm2 for the quadrupole diodes over 10 years. These relatively low doses may allow the use of diffusion type diodes instead of epitaxial diodes. The electrical characteristics of several diodes were measured at temperatures in the range between 1.8 K and 300 K. Diffusion type diodes from three manufacturers were submitted to high current endurance tests in liquid helium. Electrical characteristics and temperatures were measured versus time and showed acceptable results. First irradiation tests show that modified diffusion diodes can be used at least for the dipole by-pass.
KeywordsBoron Helium Lime Expense Gallium
Unable to display preview. Download preview PDF.
- 1.L. Burnod, J. B. Jeanneret, and H. Schönbacher. Expected doses inside and around LHC dipoles, AC/DI/FA/ Note 93–06 (1993)Google Scholar
- 2.G. Stevenson, Private communication, 16.06.97Google Scholar
- 3.V. Berland, D. Hagedorn, A. Gharib, Power diodes submitted to radiation at 77 K in an accelerator environment — target T6 of TCC2 in the SPS -, CERN/LHC-ICP/VB 95–125, Internal note, July 1995.Google Scholar
- 5.D. Hagedorn, W. Nägele, Quench protection diodes for the LHC at CERN, “Advances in Cryogenic Engineering (Materials)”, Vol.38, 1992Google Scholar
- 6.V. Berland, D. Hagedorn, A. Gharib, Comparison between two types of power diodes submitted to high current cycle endurance tests, CERN/LHC-ICP/VB 96–01, Internal Note April 1996Google Scholar
- 7.V. Berland, D. Hagedorn, H. Gerstenberg, Behaviour of the future LHC magnet protection diodes irradiated in a nuclear reactor at 4.6 K with intermediate annealing, RADiation Effects on Components and Systems conference (RADECS 95), Arcachon-France, September 1995.Google Scholar