Experimental observation of return current effects in passive plasma lenses

Govil, R.; Leemans, Wim

doi:10.1063/1.58857

Cited by 2 publications

(3 citation statements)

References 3 publications

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“…The higher the ion beam energy and the worse the ion beam quality, the higher the cost of cooling. Accumulation and cooling must be introduced into the accelerator system at an energy level far above that of the ion source extraction energy, in order to make use of the rise of the intensity limit, which grows with β 3 = (v i /c) 3 (Eq. 1).…”

Section: Applicationsmentioning

confidence: 99%

“…In the past a few cases of successful neutralization schemes for low-energy charged particle beams with particle clouds or beams of opposite polarity or with a low-density plasma have been demonstrated [1,2,3]. A new method of neutralizing heavy-ion beams with intense pulsed, low-energy electron beams generated by ferroelectrically-driven electron guns has recently been experimentally applied to the extraction from a laser ion source and is reported in Refs.…”

Section: Introductionmentioning

confidence: 99%

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Neutralization principles for the extraction and transport of ion beams

Riege¹

2000

Nuclear Instruments and Methods in Physics Research Section A:

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The strict application of conventional extraction techniques of ion beams from a plasma source is characterized by a natural intensity limit determined by space charge.The extracted current may be enhanced far beyond this limit by neutralizing the space charge of the extracted ions in the first extraction gap of the source with electrons injected from the opposite side. The transverse and longitudinal emittances of a neutralized ion beam, hence its brightness, are preserved. Results of beam compensation experiments, which have been carried out with a laser ion source, are resumed for proposing a general scheme of neutralizing ion sources and their adjacent low-energy beam transport channels with electron beams. Many technical applications of high-mass ion beam neutralization technology may be identified: the enhancement of ion source output for injection into high-intensity, low-and high-energy accelerators, or ion thrusters in space technology, for the neutral beams needed for plasma heating of magnetic confinement fusion devices, and for future accelerator-driven systems for fusion, fission and nuclear waste incineration. The strict application of conventional extraction techniques of ion beams from a plasma source is characterized by a natural intensity limit determined by space charge. The extracted current may be enhanced far beyond this limit by neutralizing the space charge of the extracted ions in the first extraction gap of the source with electrons injected from the opposite side. The transverse and longitudinal emittances of a neutralized ion beam, hence its brightness, are preserved. Results of beam compensation experiments, which have been carried out with a laser ion source, are resumed for proposing a general scheme of neutralizing ion sources and their adjacent low-energy beam transport channels with electron beams. Many technical applications of high-mass ion beam neutralization technology may be identified: the enhancement of ion source output for injection into high-intensity, low-and high-energy accelerators, for ion thrusters in space technology, for the neutral beams needed for plasma heating of magnetic confinement fusion devices, and for future accelerator-driven systems for fusion, fission and nuclear waste incineration. CERN LHC/2000-5

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Section: Applicationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Neutralization principles for the extraction and transport of ion beams

Riege¹

2000

Nuclear Instruments and Methods in Physics Research Section A:

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“…The beam-plasma system is the subject of many recent investigations motivated by applications such as plasma wake eld acceleration schemes 9], including the most recent E-157 experiment 10,11], the use of plasma lenses for beam focusing 12,13,14,15], applications of intense beamsfor plasma heating 16,17], microwave generation 18] and ion acceleration 19]. Di erent aspects of beamdynamics in a plasma have beeninvestigated including detailed calculations of the induced return plasma currents without 20] and with 21,22] the e ect of collisions between plasma electrons and ions, with and without an externally applied static magnetic eld 23].…”

Section: Introductionmentioning

confidence: 99%

Collisionless relaxation in beam-plasma systems

Backhaus

2001

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This thesis reports the results from the theoretical investigations, both numerical and analytical, of collisionless relaxation phenomena in beam-plasma systems. Many results of this work can also be applied to other lossless systems of plasma physics, beam physics and astrophysics.Di erent aspects of the physics of collisionless relaxation and its modeling are addressed. A new theoretical framework, named Coupled Moment Equations (CME), is derived and used in numerical and analytical studies of the relaxation of second order moments such as beam size and emittance oscillations. This technique extends the well-known envelope equation formalism, and it can be applied to general systems with nonlinear forces. It is based on a systematic moment expansion of the Vlasov equation. In contrast to the envelope equation, which is derived assuming constant rms beam emittance, the CME model allows the emittance to vary through coupling to higher order moments. The CME model is implemented in slab geometry in the absence of return currents. The CME simulation yields rms beam sizes, velocity spreads and emittances that are in good agreement with particle-in-cell (PIC) simulations for a wide range of system parameters.The mechanism of relaxation is also considered within the framework of the CME system. It is discovered that the rapid relaxation or beam size oscillations can be attributed to a resonant coupling between di erent modes of the system. A simple analytical estimate of the relaxation time is developed.The nal state of the system reached after the relaxation is complete is investigated. New and accurate analytical results for the second order moments in the phase-mixed 2 state are obtained. Unlike previous results, these connect the nal values of the second order moments with the initial beam mismatch. These analytical estimates are in good agreement with the CME model and PIC simulations. Predictions for the nal density and temperature are developed that show main important features of the spatial dependence of the pro les. Di erent aspect of the nal coarse-grained state such as its non-thermal nature, the appearance of 'hot' regions on the periphery and the core-halo character of the density are investigated.Professor Jonathan S. Wurtele Dissertation Committee Chair iii To my grandmothers, whose di erent lives were always an inspiration...

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Experimental observation of return current effects in passive plasma lenses

Cited by 2 publications

References 3 publications

Neutralization principles for the extraction and transport of ion beams

Neutralization principles for the extraction and transport of ion beams

Collisionless relaxation in beam-plasma systems

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