BNL, Upton, Long Island, New York, USA
Stony Brook University, Stony Brook, USA
BNL, Upton, Long Island, New York, USA
eRHIC project requires construction of a FFAG ring to accelerate electrons and connect to the existing ion ring of Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. This new ring will have the same radius as the RHIC ring. Synchrotron radiation lost in the electron ring should be compensated by a CW superconducting radio frequency (SRF) cavity. Here we propose an 845 MHz single cell harmonic cavity. This cavity will experience a high average current (∼0.7 A) passing through it. With this consideration, this cavity design requires optimization to reduce higher order mode power. On the other hand, the cavity will operate at relatively high gradient up to 18 MV/m. Current design requires fundamental couplers to handle 400 kW forward RF power and HOM couplers to extract 2.5 kW HOM power.
This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
BNL, Upton, Long Island, New York, USA
A 422 MHz cavity was designed for high current FFAG lattice ERLs for high luminosity eRHIC. The cavity was optimized to be able to propagate all the HOMs out of the cavity for high BBU threshold current and low HOM power (loss factor). Coupling the full spectrum (up to 30 GHz) HOMs out of the cavity and delivering the HOM power (up to 8 kW) out of the cryomodule is a challenge. A damping scheme with 6 coaxial line HOM couplers for low frequency HOMs and 3 waveguide HOM dampers for high frequency (so that the waveguide is small) is proposed to damp the full spectrum and high power HOMs. This paper will present the cavity design and HOM damping scheme.