Plans for the extraction of intense beams of H- ions from the TRIUMF cyclotron

Plans are presented for the cw extraction of H- ions from TRIUMF for subsequent injection into an accumulation ring. For the injection of thousands of turns only charge changing processes are practicable and H- ions offer more flexibility than H0 atoms. The mean radius gain per turn at extraction, 1.5 mm, can be tripled by auxiliary RF cavities which increase the energy gain per turn from 0.3 to 1.0 MeV. The turn separation at a deflector entrance may also be augmented by precessional techniques using the ν/subR/ = 3/2 resonance. The H- beam then enters an electrostatic deflector with a positive voltage followed by a second deflector and standard magnetic channels. The orbit codes have been modified to obtain trajectories in extended regions of time-varying electromagnetic field. Emittance, intensity and efficiency of extraction are discussed together with the tolerances required. The conceptual design of the deflection elements and the RF cavities and amplifiers is described. Alternative schemes for the extraction of H0 atoms and H- ions in 200 turn packets are briefly reviewed