DESIGN AND FABRICATION OF THE CORNELL ERL INJECTOR CRYOMODULE*

The Energy Recovery Linac (ERL) development effort at Cornell will first produce an ERL beam source [1]. A portion of the source is an SRF Injector cryomodule to accelerate a cw beam with 2 ps bunch length and 100 mA average current from an input energy of 0.3 MeV to an output energy of 5-15 MeV while preserving an emittance of 1 mm-mrad. The Injector cryomodule is based on TTF III technology with modifications for cw operation. In this technology, the cavity helium vessels are pumped to 1.8K (12 Torr) through a common 10 Helium Gas Return Pipe (HGRP) from which the beamline is suspended. All of the 1.8K cryomodule components are surrounded by 5K intercepts to minimize heat leak to 1.8K, and the 5K intercepts are likewise surrounded by 80K intercepts. To deliver the 0.5 MWCW average power to the beam, the Injector cryomodule contains five 1.3 GHz SRF 2-cell cavities, each cavity having two 50 kWCW coax couplers to deliver power from five 100 kWCW klystrons. Cold beamline HOM loads are placed between each cavity and outboard of the first and last cavities. The description of the ERL Injector cryomodule will begin with the SRF cavities and progress outward to the vacuum vessel. Insight gained from the fabrication process that will benefit the future ERL Linac cryomodule design will be highlighted.