Probability of burn-through of defective 13 kA splices at increased energy levels

In many 13 kA splices in the machine there is a lack of bonding between the superconducting cable and the stabilising copper along with a bad contact between the bus stabiliser and the splice stabiliser. In case of a quench of such a defective splice, the current cannot bypass the cable through the copper, hence leading to excessive local heating of the cable. This may result in a thermal runaway and burn-through of the cable in a time smaller than the time constant of the circuit. Since it is not possible to protect against this fast thermal run-away, one has to limit the current to a level that is small enough so that a burn-through cannot occur. Prompt quenching of the joint, and quenching due to heat propagation through the bus and through the helium are considered. Probabilities for joint burn-through are given for the RB circuit for beam energies of 3.5, 4 and 4.5 TeV, and a decay time constant of the RB circuit of 50 and 68 s.