This is a preprint of a paper intended forpubli_tion in • jourual orproceedin8_. Since : " _:__: changesmay be madebefore publication,thispreprint is madeavailablewith the ", i_i: ii understanding that it will not be cited or reproduced without the permission of the :.

We have recently initiated an investigation of elecii .. llii i This work was performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under contract no. W-7405-Eng-48.

This h a preprint of a p a~i n~n d e d forpubliotion in a jotun?l or proceeding. Since changes may be nude before pnbliotion, this preprint is made available with the understanding ttut it will not be ated or reproduced without the permhion of the author. We have measured an 36-A-~m-~ current emission density over the surface area of an 11.4-cm2-area Lead-Titanate-Zmonate @T) ferroelectric cathode with a pulsed andcathode (A-K) potential of 50 kV. We have also observed currents above those pfedicted by classical Child-Langmuir formula for a wide variety of cases. Since a plasma within the A-K gap could also lead to increase current emission we are attempting to measure the properties of the plasma near the cathode surface at emission time. In other measurements, we have observed strong gap currents in the absence of an A-K potenrial. Further, we continue to make brightness measurements of the emitted beam and observe spatially non-uniform emission and large shot-to-shot variation. Measurements show individual beamlets with a brightness as high 10lr Am-2rad-2. 7 DISCLAIMER

No abstract

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)