A PROTOTYPE TARGET WHEEL FOR THE ILC POSITRON SOURCE

In this paper we describe the design, construction and commissioning of a prototype based on the positron production target wheel planned for the International Linear Collider (ILC) positron source. The eciency of the current baseline positron source design for the ILC can be improved if the conversion target is partially immersed in the magnetic eld of the capture optics, thereby increasing the overall capture eciency for positrons by a factor of two or more. However, immersion of the rotating target wheel generates strong eddy currents leading to additional heating and stresses on the wheel. The primary purpose of our prototype, which has been assembled at Daresbury Laboratory, is to investigate the eects of eddy currents induced in a titanium alloy wheel moving with rim speeds up to 100 ms