High Duty Factor, Monochromatic Extraction from EROS

Simulations of the monochromatic extraction process in the pulse stretcher ring (PSR) of the Saskatchewan Accelerator Laboratory have been done using several different RF techniques. The effects of the extraction sextupoles on circulating particles cancel over several turns unless the PSR tune approaches a 1/3 integer resonance condition. This is accomplished by having a large chromaticity (-15) and allowing the energy of the particles to decrease either through synchrotron radiation losses or by changing the RF frequency of the PSR cavity. In the synchrotron loss mode the particles can be delayed by trapping them in the RF bucket and spilling them at a later time by abruptly lowering the RF voltage. Results indicate that it should be possible to extract a beam with a duty factor greater than 70%, an energy spread of ±10-4 and horizontal emittance less than 0.8 mm-mrad for all operating energies.