Systematic investigations and improvements of the efficiency, purity and emittance of charge bred ion beams from the TRIUMF charge state booster.

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The TRIUMF charge state booster (CSB) raises the charge state of ions from rare isotopes prior to injection into the ISAC-I linac. Therewith, it allows the post acceleration of isotopes from elements beyond mass 30 and avoids the stripping of ions at very low kinetic energies downstream the ISAC-I Radio Frequency Quadrupole (RFQ) into an A/q mass range below 7. An inherent issue of the CSB is the operation vacuum pressure. An ECRIS does not operate at Ultra High Vacuum (UHV), which is the cause of the high level of impurities in such devices, which is an issue when dealing with very low radioactive ion intensities. However, the 1+ ->n+ conversion rate depends on the flexibility of the injection optics, the plasma conditions, the plasma confinement and the beam formation upon ion extraction, which can be optimized. The ECRIS is definitely superior to an EBIS related to the production of intense beams of rare isotopes >10^9 per second. ***The main objective of this proposal is to improve the TRIUMF CSB performance in terms of beam quality, charge breeding efficiency and beam purity, by introducing techniques which are used or under investigation at other ECRIS systems. The goal is to bring TRIUMF into the international leadership in charge breeding with ECRIS devices and to deliver higher quality and new beams to the experiments. As the injection- and the ionisation efficiency as well as the beam purity essentially depend on the plasma conditions, the two-frequency heating and the tuning of the microwave frequency, will be introduced. These techniques rely on the generation of plasma modes that allow higher plasma densities and optimum coupling of the rf-power. The project described in this proposal intends to investigate systematically the charge breeding efficiency and the beam quality by ***- modifying the plasma conditions using two frequency heating and frequency tuning***- variation of the plasma chamber working gas pressure, use of UHV technology associated with the control of the plasma chamber material and the support gas composition***- beam emittance measurements using a slit-slit emittance scanner and corresponding beam extraction calculations.***In addition, the CSB will be modified by adding a high temperature oven, to exploit a new type of beam delivery via the production of highly charged ion beams from samples in the solid state. The oven need to be resistive against reactive metals, in particular for Ti-isotopes. The goal is to demonstrate a lifetime of the oven for at least several days Ti operation. This can be used to deliver long lived 44Ti (t1/2 =59Y) to users at TRIUMF.***The significant improvement of the CSB beam properties and additional beam production capabilities will benefit the experimental program at ISAC in particular for accelerated beam experiments. The second aspect is the training of highly qualified personnel in the field of plasma ion sources in general and on ECRIS sources in particular.