D0 - Chimeny Lead Quench Detection, Beta Solenoid
A.T. Visser · 1993
The voltage drop across the superconducting chimney lead is sensed to detect a quench. The return sense lead is mounted outside the chimney. The return sense lead and the superconducting chimney wire form a loop with area A {approx} 1.7 m{sup 2} (information from R. Ru. cinski). Changing flux through area A will induce a voltage in the sense loop and could cause false quench detection. Assume that the field through A changes 1 kGauss (0.1 Wb/m{sup 2}) in 10{sup -3} sec. The induced voltage is then: e = d0/dt = dBA/dt and e = 0.1 x 1.7/10{sup -3} = 170 V. This is probably a very pessimistic estimate, but it shows that we have to watch out. Changes of 100 Gauss in 100 msec (CDF experience?) are probably more likely and cause: e = 0.01 x 1.7/10{sup -2} {approx} 1.7 V noise. This noise is still too high because trip levels are planned to sit at {approx}50 mV? It is practically impossible to predict what the real noise values would be, but I expect them to be in the order of 1 to 10 V. This is more than we can handle and I would expect nuisance trips.