CONSTRUCTION OF A LARGE THIN SOLENOID MAGNET.

A large thin solenoid, VENUS, was constructed and an excitation test without iron yoke was performed. New methods to keep high transparency for particles were applied to this solenoid. These methods were developed through a small sized superconducting model and a real sized non-superconducting model. VENUS coil was fabricated by a 'welding method' which is suited for very thin solenoids. Good cooling property of the coil was obtained by this method. Long aluminum-stabilized superconducting cable was developed. An extruded hollow aluminum coil-case was used for the coil to reduce the radiation thickness. A coil support system was tested at cooldown and excitation of the coil. It did not need re-adjustment after cooldown and did not give distinguishable effects to the coil. A large outer cylinder made of CFRP was useful for the vacuum vessel needed for the transparency.