Excitation of a superconducting large thin solenoid magnet

A superconducting large thin solenoid magnet was contructed for the VENUS detector in the TRISTAN 30 GeV e+e- collider. The magnet has a 3.4 m warm bore diameter and a 5.24 m usable length with a material thickness of 0.52 radiation length. The first excitation was successfully performed up to 4000 A with no quench. Several forced quenches using a heater mounted on the coil were made to check the safety of operation. The quench propagation velocity was clearly measured in these quenches. The “quench back” phenomenon was observed about one second after the shut off of the power supply. The field quality of the magnet was found to be uniform within an accuracy of 0.3 per cent. The success of the first excitation was immediately followed by the assembly of the detector. VENUS was rolled into the TRISTAN collider storage ring and is now prepared for the first collision of e+ and e-.