Ion source and injector development is one of the major parts of the HIF program in the USA. Our challenge is to design a cost effective driver-scale injector and to build a multiple beam module within the next couple of years. In this paper, several currentvoltage scaling laws are summarized for guiding the injector design. Following the traditional way of building injectors for HIF induction linac, we have produced a preliminary design for a multiple beam driver-scale injector. We also developed an alternate option for a high current density injector that is much smaller in size. One of the changes following this new option is the possibility of using other kinds of ion sources than the surface ionization sources. So far, we are still looking for an ideal ion source candidate that can readily meet all the essential requirements.
We are developing high-current ion sources for Heavy Ion Fusion applications. Our proposed RF plasma source starts with an array of high current density mini-beamlets (of a few mA each at ~100 mA/cm 2) that are kept separated from each other within a set of acceleration grids. After they have gained sufficient kinetic energy (>1.2 MeV), the mini-beamlets are allowed to merge together to form a high current beam (about 0.5 A) with low emittance. Simulations have been done to maximize the beam brightness within the physical constraints of the source. We have performed a series of experiments on an RF plasma source. A 80-kV 20-µs source has produced up to 5 mA of Ar + in a single beamlet and we measured the emittance of a beamlet, its energy spread, and the fraction of ions in higher charge states. We have also tested a 50-kV 61-hole multibeamlet array. Two upcoming experiments are being prepared: the first experiment will test full-gradient extraction and transport of 61 beamlets though the first four electrodes, and the second experiment will converge 119 beamlets into an ESQ channel at one-quarter scaled voltage of a 1.6 MV HIF injector. TH.P-12; PAC codes: (07.77.Ka Charged-particle beam sources and detectors)(41.85.Ar Beam extraction, beam injection)(29.27.Ac Beam injection and extraction)
In a typical heavy ion fusion driver design, the induction linac requires a multiple beam injector. We present a conceptual design for an 84-beam injector system with each beam channel carrying 0.5 A of beam current. Each channel starts with a 10-cm diameter surface ionization source followed by a 1.7 MV electrostatic Einzel lens-type preaccelerator and an electrostatic quadrupole (ESQ) matching section.The preaccelerator and matching section are 0.7 m and 5.0 m long respectively. The array has an overall diameter of 3.0 m at the ion source end and 1.0 m diameter at the exit.
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