Dear Harold,
The attached MS Word file E951'82K.doc presents an EasyPlot graph of I(t), R(t)
and their product V(t) for our E951 magnet energized from 82 K by a fully
regulated power supply. The power supply has two-quadrant capability (supplies
negative as well as positive voltage). I assume--very conservatively?--that the
supply ramps to full voltage in 0.5 seconds. I assume a circuit resistance of
one milliohm--about the minimum likely with bus work of reasonable cost.
The graph considers three voltages. 671 V is the minimum to reach 7.2 kA--with
no flat top. 684 V reaches 7.2 kA with 20% less dissipation--23.2 MJ instead of
29.0 MJ. 704 V allows a flat top of 1.0 seconds, with dissipation--25.0
MJ--about 16% less than the 29.6 MJ with 678 V, the minimum that can give a flat
top of 1 second.
Another graph, E951V82K.doc, shows the reduction in dissipation (read: liquid
nitrogen consumption) and temperature rise bought by using a larger power
supply.
Good luck at CERN,
Bob W.