Collective focusing of intense ion beam pulses for high-energy density physics applications

Dorf, M.; Kaganovich, Igor; Startsev, Edward A.; Davidson, Ronald C.

doi:10.1063/1.3557894

Cited by 8 publications

(9 citation statements)

References 26 publications

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“…16 However, the technical realization of the final beam focus can be significantly simplified if the collective focusing scheme (hereafter referred to as a collective focusing lens) is used. 17,18 In particular, a much weaker magnetic field (several hundred Gauss) would be required to achieve the same final focal length.…”

Section: B Collective Focusing Lens For the Beam Final Focusmentioning

confidence: 99%

“…solenoid). 17,18 Note that the NDCX-I configuration conveniently allows the ion beam pulse to extract neutralizing electron background from the plasma that fills the magneticfield-free drift section.…”

Section: B Collective Focusing Lens For the Beam Final Focusmentioning

confidence: 99%

“…However, it should also be pointed out that the collective effects of a neutralizing electron background in a weak solenoidal magnetic field were also utilized in a magnetic focusing scheme proposed by S. Robertson a few decades ago. 19 In this section we review this focusing scheme, discuss extension of the original theoretical model, 17 and finally, asses the possibility of its implementation for final focusing of intense ion beams in the NDCX-II.…”

Section: Collective Focusing Lens For the Beam Final Focusmentioning

confidence: 99%

“…17,19 We consider a neutralized ion beam pulse moving from a region of a zero magnetic field into a solenoidal magnetic lens. As the charge particles traverse the field fall-off region, where the magnetic field has a non-zero radial component they acquire angular rotation around the lens axis.…”

Section: A Collective Focusing Lensmentioning

confidence: 99%

“…30,31 Along with the ions, a free-moving electron background is also produced, and therefore it is appealing to utilize the collective focusing concept for collimation of the generated ion beam pulse. 17 However, in these applications the ion beam radius is typically larger than the collisionless electron skin depth, and therefore the condition in Eq. (38) is violated.…”

Section: A Collective Focusing Lensmentioning

confidence: 99%

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Enhanced collective focusing of intense neutralized ion beam pulses in the presence of weak solenoidal magnetic fields

et al. 2012

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The design of ion drivers for warm dense matter and high energy density physics applications and heavy ion fusion involves transverse focusing and longitudinal compression of intense ion beams to a small spot size on the target. To facilitate the process, the compression occurs in a long drift section filled with a dense background plasma, which neutralizes the intense beam self-fields. Typically, the ion bunch charge is better neutralized than its current, and as a result a net selfpinching (magnetic) force is produced. The self-pinching effect is of particular practical importance, and is used in various ion driver designs in order to control the transverse beam envelope. In the present work we demonstrate that this radial self-focusing force can be significantly enhanced if a weak (B $ 100 G) solenoidal magnetic field is applied inside the neutralized drift section, thus allowing for substantially improved transport. It is shown that in contrast to magnetic self-pinching, the enhanced collective self-focusing has a radial electric field component and occurs as a result of the overcompensation of the beam charge by plasma electrons, whereas the beam current becomes well-neutralized. As the beam leaves the neutralizing drift section, additional transverse focusing can be applied. For instance, in the neutralized drift compression experiments (NDCX) a strong (several Tesla) final focus solenoid is used for this purpose. In the present analysis we propose that the tight final focus in the NDCX experiments may possibly be achieved by using a much weaker (few hundred Gauss) magnetic lens, provided the ion beam carries an equal amount of co-moving neutralizing electrons from the preceding drift section into the lens. In this case the enhanced focusing is provided by the collective electron dynamics strongly affected by a weak applied magnetic field. V C 2012 American Institute of Physics. [http://dx.

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Section: B Collective Focusing Lens For the Beam Final Focusmentioning

confidence: 99%

Section: B Collective Focusing Lens For the Beam Final Focusmentioning

confidence: 99%

Section: Collective Focusing Lens For the Beam Final Focusmentioning

confidence: 99%

Section: A Collective Focusing Lensmentioning

confidence: 99%

Section: A Collective Focusing Lensmentioning

confidence: 99%

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Enhanced collective focusing of intense neutralized ion beam pulses in the presence of weak solenoidal magnetic fields

et al. 2012

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Neutron and Proton Diagnostics for Pulsed Plasma Fusion Devices

Talebitaher

Springham

2017

Plasma Science and Technology for Emerging Economies

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The self-focusing condition of a charged particle beam in a resistive plasma

Ning

Liang

et al. 2021

J. Plasma Phys.

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The self-focusing condition of a charged particle beam in a resistive plasma has been studied. When plasma heating is weak, the beam focusing is intensified by increasing the beam density or velocity. However, when plasma heating is strong, the beam focusing is only determined by the beam velocity. Especially, in weak heating conditions, the beam trends to be focused into the centre as a whole, and in strong heating conditions, a double-peak structure with a hollow centre is predicted to appear. Furthermore, it is found that the beam radius has a significant effect on focusing distance: a larger the beam radius will result in a longer focusing distance. Simulation results also show that when the beam radius is large enough, filamentation of the beam appears. Our results will serve as a reference for relevant beam–plasma experiments and theoretical analyses, such as heavy ion fusion and ion-beam-driven high energy density physics.

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Collective focusing of intense ion beam pulses for high-energy density physics applications

Cited by 8 publications

References 26 publications

Enhanced collective focusing of intense neutralized ion beam pulses in the presence of weak solenoidal magnetic fields

Enhanced collective focusing of intense neutralized ion beam pulses in the presence of weak solenoidal magnetic fields

Neutron and Proton Diagnostics for Pulsed Plasma Fusion Devices

The self-focusing condition of a charged particle beam in a resistive plasma

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