40 kA dumping system for the ISR beams

The kinetic energy of the proton beam of each ISR is W = I x E x T/sub rev/. With the maximum value of current achieved so far in the ISR I approximately equal to 30 A, a proton energy E = 26 GeV, and a revolution time T/sub rev/ = 3.15 μs, the result is a maximum kinetic energy of W = 2.45 MJ. Such an energy, if suddenly lost and instantaneously dissipated in any part of the ISR, would cause a major breakdown. It was therefore necessary to build a fast and reliable system which could dump the beam whenever safety monitors indicated a hardware fault or a beam loss. The beam in each ISR is dumped by means of four fast pulsed magnets deflecting the particles vertically onto an absorber block situated in the same long straight section. In 1970, when the ISR was first put into operation, each of the four magnets in each ring was energized independently by its own 3 Ω pulse generator. By means of a special spark-gap developed for that purpose, and by switching together the four 3 Ω pulse-forming networks, it was possible to improve significantly the reliability of the system. The 0.75 OMEGA, 40 kA pulse generator now energizing the four fast pulsed magnets is described, with special attention given to the principles and technological solutions which were adopted in order to achieve the necessary reliability of the system for each type of operation, particularly during long colliding beam experiments. (auth)