CEBAF energy recovery experiment

Abstract

A successful GeV scale energy recovery demonstration with high ratio of accelerated-to-recovered energies (501) was recently carried out on the CEBAF recirculating linear accelerator. Future high energy (multi-GeV), high current (hundreds of milli-Amperes) beams would require gigawatt-class RF systems in conventional linacs -a prohibitively expensive proposition. However, invoking energy recovery [I] alleviates extreme RF power demands; required RF power becomes nearly independent of beam current, which improves linac efficiency and increases cost effectiveness. Funhermore, energy recovering linacs promise efficiencies of storage rings, while maintaining beam quality of linacs: superior emittance and energy spread and short bunches (sub-pico sec,). Finally, energy recovery alleviates shielding, if the beam is dumped below the neutron production threshold. Jefferson Lab has demonstrated its expertise in the field of Energy Recovery Linacs (ERLs) with the successful operation of the Infrared FEL, where 5 mA of average beam current have been accelerated up to 50 MeV and the energy stored in the beam was recovered via deceleration and given back to the RF power source. To date this has been the largest scale demonstration of energy recovery.

Implications of beam filling patterns on the design of recirculating energy recovery linacs

“…So, σ V turn of pattern DSPO is larger, which makes it nonoptimal for static set points according to Eq. (25).…”

“…By adjusting the delay length or by implementing more sophisticated arcs, topologies, and injection scheme, one can manipulate the bunch order or bunch spacing. The extra path length can be in the form of a longer arc [24] or a chicane [25]. By introducing this additional path length, the topology changes from the "0" topology of Fig.…”

“…When m ¼ n ¼ 0, the bunch flips phase but remains in the same packet; which is the case of the simple recirculating FIFO scheme described in earlier sections. The beam line layout described in [25] can be an example of this. When m, n ≠ 0, the bunches do not only flip phase, but also move to later blocks and packets.…”

Design and Principles of Linear Accelerators and Colliders

“…Successful operations of high-power FEL drivers stimulated community interest in ERL technology, and there followed numerous proposals and a number of actual systems. These included: FEL drivers: the JLab IR Upgrade FEL [127], ALICE [128], and the JLab UV Demo FEL [129]; test facilities: CEBAF-ER [130], the KEK cERL [131], bERLinPro [132], ER@CEBAF [133], and PERLE [134,135]; and systems associated with nuclear physics facilities: the BNL test ERL, an electron cooler concept [136], MESA [137], and most recently, conversion of the Darmstadt S-DALINAC to an ERL [138].…”

Large dynamic range beam profile measurements

“…Continuous operation of an ERL requires that the beam loss from injection to energy recovered beam dump be typically less than 1ppm. The JLAB Energy Recovery [ER] experiment is a test of the energy recovery concept using a large number of RF cavities [5]. The electron beam is injected with 55MeV(20MeV) of energy, accelerated to 1GeV and the phase shifted 180 • and energy recovered through the RF section back down to the injected energy.…”