1993 年 28 巻 4 号 p. 199-208
In order to increase the luminosity of the TRISTAN electron-positron collider, eight superconducting quadrupole magnets are required. For this purpose, KEK has developed an iron-free quadrupole with a field gradient of 70T/m. It has an inner diameter of 140mm and an effective length of 1.145m. The coils, which are of cos 2Θ type, are made from four layers of 27-strand NbTi Rutherford-type cable with Kapton insulation and firmly clamped with 316LN stainless steel collars. Following the successful test of a prototype, nine quadrupoles were manufactured by industry, for which KEK provided all scientific and tehnical information about the magnet, and were installed in the TRISTAN main ring. Since they were commissioned in January 1991, the eight quadrupoles have been operated without trouble and the luminosity has been improved up to about twice the old value. The total operating time of the magnets is presently about 10, 000 hours. In this paper, a brief description of the magnets and the results of the tests as well as the experience over the first two years of operation are presented.