WG2005
BNL, Upton, Long Island, New York, USA
We present a lattice design of future ERL-based electron-hadron collider eRHIC and BNL version of the lattice design LHeC . In eRHIC, an six-pass ERL installed in the existing Relativistic Heavy Ion Collider (RHIC) tunnel will collide 5-30 GeV polarized electrons with RHIC's 50-250 (325) GeV polarized protons or 20-100 (130) GeV/u heavy ions. In BNL's version for LHeC, a stand-along 3-pass 60 GeV CW ERL will collide polarized electrons with 7 TeV protons. The multiple arcs are made of Flexible Momentum Compaction lattice (FMC) allowing adjustable R56 parameter. The multiple arcs, placed above each other, are matched to the linacs straight sections with splitters and combiners. Other important eRHIC lattice components have been developed: quadrupole-less linac optics; by-pass lines around the detectors and the pass lengthening insertion (needed to match the bunch frequencies of the electrons and hadrons in wide hadron energy range).
WG2015
BNL, Upton, Long Island, New York, USA
Transverse beam break up instability is one of the main limited factor to achieve high average current operation in Energy Recovery Linacs. 30 GeV ERL is considered as an electron source for electron ion collider (eRHIC) at BNL. The full scale ERL consist of 6 passes up and 6 passes dawn through 2 SRF linacs with ~2.5 GeV gain energy each. The average current required for eRHIC is 50 mA from injector. The full scale machine has to be capable to operate at various top energies (from 5 to 30 GeV). We will present results of BBU threshold calculation based on new design BNL3 SRF cavity with HOMs dumping for different top energy settings and discuss possible scenarios to satisfy the requirements.