RF Plasma source for a Heavy Ion Fusion injector

.We have performed experiments and modeling to evaluate a proposed merging beamlet approach for use in a compact high-brightness Heavy Ion Fusion injector. We used an RF plasma source to produce the initial beamlets. An extraction current density of 100 mA/cm 2 was achieved, and the thermal temperature of the ions was below 1 eV. An array of converging beamlets was used to produce a beam with the envelope radius, convergence, and ellipticity matched to an electrostatic quadrupole channel. Experimental results were in good quantitative agreement with computer simulations and have demonstrated the feasibility of this concept. The size of a driver-scale injector system using this approach will be several times smaller than one designed using traditional single large-aperture beams. The success of this experiment has possible significant economical and technical impacts on the architecture of HIF drivers.

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“…The thermal temperature of the ions was below 1 eV. Additional details about the rf plasma source have been published 2,3 .…”

Section: Individual Beamletsmentioning

confidence: 99%

A multi-beamlet injector for heavy ion fusion: Experiments and modeling

Westenskow

Grote

Bieniosek

et al. 2007

2007 IEEE Particle Accelerator Conference (PAC)

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“…An electrostatic energy analyzer (EEA) is used to measure the beam energy and beam energy distribution. We have used cylindrical 90-degree-bend analyzers with first order focus [7] to measure the time evolution of the mean beam energy in HCX [2] and the rate of charge exchange of beam ions in a gas source on STS-100 [8]. In addition to its utility as an energy analyzer, the EEA can also be used to discriminate and analyze beam ions that have been doubly ionized by interaction with ambient gas.…”

Section: Thi-10mentioning

confidence: 99%

Diagnostics for intense heavy-ion beams in the HIF-VNL

Bieniosek

Eylon

Faltens

et al. 2005

Nuclear Instruments and Methods in Physics Research Section A:

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Modern diagnostic techniques provide detailed information on beam conditions in injector, transport, and final focus experiments in the HIF-VNL. Parameters of interest include beam current, beam energy, transverse and longitudinal distributions, emittance, and space charge neutralization. Imaging techniques, based on kapton films and optical scintillators, complement and in some cases, may replace conventional techniques based on slit scans. Time-resolved optical diagnostics that provide 4-D transverse information on the experimental beams are in operation on the existing experiments. Current work includes a compact optical diagnostic suitable for insertion in transport lines, improved algorithms for optical data analysis and interpretation, a high-resolution electrostatic energy analyzer, and an electron beam probe. A longitudinal diagnostic kicker generates longitudinal space-charge waves that travel on the beam. Time of flight of the space charge waves and an electrostatic energy analyzer provide an absolute measure of the beam energy. Special diagnostics to detect secondary electrons and gases desorbed from the wall have been developed.

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“…For operation with 10 kW of drive powers we estimated that less than 5% of the extracted ions were in the Ar ++ state. Additional details about the rf plasma source have been published 2,3,4 .…”

Section: Studying Individual Beamletsmentioning

confidence: 99%

“…We have tested a 61-beamlet extraction array using a series of Einzel lens 4 . The source apertures were 2.2 mm in diameter while all the other electrodes had 4.0 mm diameter holes.…”

Section: Full Gradient Experimentsmentioning

confidence: 99%

A Compact High-Brightness Heavy-Ion Injector

Westenskow

Grote²,

Halaxa³

et al.

Proceedings of the 2005 Particle Accelerator Conference

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To provide a compact high-brightness heavy-ion beam source for Heavy Ion Fusion (HIF) accelerators, we have been experimenting with merging multi-beamlets in an injector which uses an RF plasma source. In an 80-kV 20-microsecond experiment, the RF plasma source has produced up to 5 mA of Ar + in a single beamlet. An extraction current density of 100 mA/cm 2 was achieved, and the thermal temperature of the ions was below 1 eV. We have tested at full voltage gradient the first 4 gaps of an injector design. Einzel lens were used to focus the beamlets while reducing the beamlet to beamlet space charge interaction. We were able to reach greater than 100 kV/cm in the first four gaps. We also performed experiments on a converging 119 multi-beamlet source. Although the source has the same optics as a full 1.6 MV injector system, these test were carried out at 400 kV due to the test stand HV limit. We have measured the beam's emittance after the beamlets are merged and passed through an electrostatic quadrupole (ESQ). Our goal is to confirm the emittance growth and to demonstrate the technical feasibility of building a driver-scale HIF injector. .

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RF Plasma source for a Heavy Ion Fusion injector

Cited by 4 publications

References 2 publications

A multi-beamlet injector for heavy ion fusion: Experiments and modeling

A multi-beamlet injector for heavy ion fusion: Experiments and modeling

Diagnostics for intense heavy-ion beams in the HIF-VNL

A Compact High-Brightness Heavy-Ion Injector

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