Intense Ion Beam for Warm Dense Matter Physics

Coleman, J. E.

doi:10.2172/929701

Cited by 4 publications

(1 citation statement)

References 34 publications

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“…Data from experiments performed on NDCX-I clearly demonstrate the importance of beam neutralization for achieving a focused ion beam. In this particular experiment, the plasma source trigger timing was varied relative to the beam trigger signal (Coleman, 2008). The scintillator images of the compressed beam in Figure 3a show that if the plasma source is triggered too early (e.g., 6 μs before the beam trigger signal), the plasma will have already begun to dissipate.…”

Section: Ferroelectric Plasma Sourcementioning

confidence: 99%

Plasma source development for the NDCX-I and NDCX-II neutralized drift compression experiments

et al. 2012

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Compressed ion beams are being studied as a driver for inertial confinement fusion energy and for the creation of matter in the high-energy-density regime. In order to facilitate compression of a positive ion charge bunch longitudinally and transversely beyond the limit determined by the space-charge field of the bunch, a source of charge-neutralizing electrons must be provided. Plasma sources have been developed for the NDCX-I and NDCX-II experimental facilities, both for the 2-m-long, field-free drift regions, and for the small-diameter interior of the multi-Tesla final focus solenoid. Barium titanate based cylinders with a high dielectric coefficient are used to line the wall of the 2-m-long drift region and by applying a 9 kV pulse between the inner and outer surfaces of the cylinders, plasma with a density in the 1010 cm−3 range is formed. Results are presented from experiments using this plasma source on NDCX-I. A compact plasma source 5.1 cm long and 3.8 cm in diameter, also made using the barium titanate based material, has been developed for use in the bore of the final focus solenoid. Plasma generated near the wall of the plasma source will follow the fringing magnetic field lines of the solenoid and help to fill the bore of the magnet with plasma. Improved designs for the barium titanate plasma sources are being considered that use different inner-surface electrode materials and structures, and also use a modified electrical driver employing a spark gap crowbar switch. In addition, plasma source designs using so-called flashboard technology have been developed. In the flashboard plasma source, high density plasma is formed when the applied high voltage pulse causes a series of breakdowns between isolated copper patches aligned in rows along the surface of the 0.2 mm thick flashboard.

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Section: Ferroelectric Plasma Sourcementioning

confidence: 99%

Plasma source development for the NDCX-I and NDCX-II neutralized drift compression experiments

et al. 2012

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Progress in beam focusing and compression for warm-dense matter experiments

Seidl

Anders

Bieniosek

et al. 2009

Nuclear Instruments and Methods in Physics Research Section A:

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Effects of errors in velocity tilt on maximum longitudinal compression during neutralized drift compression of intense beam pulses: I. general description

Kaganovich

Massidda

Startsev

et al. 2012

Nuclear Instruments and Methods in Physics Research Section A:

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A b s t r a c tNeutralized drift compression offers an effective means for particle beam pulse compression and current amplification. In neutralized drift compression, a linear longitudinal velocity tilt (head-to-tail gradient) is applied to the non-relativistic beam pulse, so that the beam pulse compresses as it drifts in the focusing section. The beam current can increase by more than a factor of 100 in the longitudinal direction. We have performed an analytical study of how errors in the velocity tilt acquired by the beam in the induction bunching module limit the maximum longitudinal compression. It is found that the compression ratio is determined by the relative errors in the velocity tilt. That is, one-percent errors may limit the compression to a factor of one hundred. However, a part of the beam pulse where the errors are small may compress to much higher values, which are determined by the initial thermal spread of the beam pulse. It is also shown that sharp jumps in the compressed current density profile can be produced due to overlaying of different parts of the pulse near the focal plane. Examples of slowly varying and rapidly varying errors compared to the beam pulse duration are studied. For beam velocity errors given by a cubic function, the compression ratio can be described analytically. In this limit, a significant portion of the beam pulse is located in the broad wings of the pulse and is poorly compressed. The central part of the compressed pulse is determined by the thermal spread. The scaling law for maximum compression ratio is derived. In addition to a smooth variation in the velocity tilt, fast-changing errors during the pulse may appear in the induction bunching module if the voltage pulse is formed by several pulsed elements. Different parts of the pulse compress nearly simultaneously at the target and the compressed profile may have many peaks. The maximum compression is a function of both thermal spread and the velocity errors. The effects of the finite gap width of the bunching module on compression are analyzed analytically.

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Intense Ion Beam for Warm Dense Matter Physics

Cited by 4 publications

References 34 publications

Plasma source development for the NDCX-I and NDCX-II neutralized drift compression experiments

Plasma source development for the NDCX-I and NDCX-II neutralized drift compression experiments

Progress in beam focusing and compression for warm-dense matter experiments

Effects of errors in velocity tilt on maximum longitudinal compression during neutralized drift compression of intense beam pulses: I. general description

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