Niowave, Inc. — Department of Energy SBIR Phase I: In the proposed collider eRHIC, hadrons from one of the RHIC storage rings will interact w

Description

In the proposed collider eRHIC, hadrons from one of the RHIC storage rings will interact with electrons accelerated in a six-pass energy recovery linac (ERL). The maximum energy of protons will be 250 GeV and the maximum energy of electrons will be 30 GeV. The machine will heavily rely on SRF technology. One accelerator physics issue being considered in the design is that the nonlinearities of the accelerating linac in the ERL produce a spread in energy which will degrade the polarization of the electron beam. One way to compensate these nonlinearities is to use a harmonic SRF linac at a multiple of the main linac frequency of 704 MHz. There are a number of challenges in developing these SRF cavities. First, related to the very high current in the ERL, is minimizing the Higher Order Mode (HOM) power generation and damping this power efficiently. Second is maximizing the real-estate gradient in the limited space available. Third is to design a cryogenic-efficient cavity. Our approach during Phase I will be to design the cavity using 3-D electromagnetic code considering good SRF properties such as minimal surface RF fields, large shunt impedance and geometry factor, good propagation of HOMs to the location we will choose for the HOM dampers, mechanical design and optimal manufacturing techniques. In Phase II we will fabricate the niobium cavity and a set of couplers and perform tests of the performance of the system.