Radiation Resistance and Life Time Estimates at Cryogenic Temperatures of Series Produced By-Pass Diodes for the LHC Magnet Protection

For the protection of the LHC superconducting magnets about 2100 specially developed by‐pass diodes have been manufactured in industry and more than one thousand of these diodes have been mounted into stacks and tested in liquid helium.By‐pass diode samples, taken from the series production, have been submitted to irradiation tests at cryogenic temperatures together with some prototype diodes up to an accumulated dose of about 2 kGy and neutron fluences up to about 3.0 1013 n cm−2 with and without intermediate warm up to 300 K.The device characteristics of the diodes under forward bias and reverse bias have been measured at 77 K and ambient versus dose and the results are presented.Using a thermo‐electrical model and new estimates for the expected dose in the LHC, the expected lifetime of the by‐pass diodes has been estimated for various positions in the LHC arcs.It turns out that for all of the by‐pass diodes across the arc elements the radiation resistance is largely sufficient. In the dispersion suppre...