Core-halo issues for a very high intensity beam

Nghiem, P.; Chauvin, Nicolas; Simeoni, W.; Uriot, D.

doi:10.1063/1.4866400

Cited by 17 publications

(19 citation statements)

References 12 publications

(11 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Even though the halo particles play such a crucial role for the beam transport; in practice, it is not easy to explicitly define the "halo." 17 In this regard, the proposed stationary distribution, Eq. (13), presents an interesting feature that the core and the halo contributions are clearly distinguishable.…”

Section: Numerical Resultsmentioning

confidence: 99%

“…Unlike the thermodynamic equilibrium of short range interacting systems, the stationary state of the beam will depend explicitly on the initial particle distribution. In this respect, different phenomena, such as, envelope mismatch, [6][7][8][9][10][11][12][13][14][15][16][17] off-axis motion, 13,[18][19][20][21][22] beam distribution nonuniformities, [23][24][25][26][27][28][29][30] and forces due to the surrounding conductors, [31][32][33] have been investigated as the precursors of the beam relaxation. Among these phenomena, the one that has attracted most attention is the envelope mismatch, which arises from the unbalance between the external focusing force and the defocussing space-charge repulsion.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Halo formation and emittance growth in the transport of spherically symmetric mismatched bunched beams

et al. 2015

View full text Add to dashboard Cite

The effect of an initial envelope mismatch on the transport of bunched spherically symmetric beams is investigated. A particle-core model is used to estimate the maximum radius that halo particles can reach. The theory is used to obtain an empirical formula that provides the halo size as a function of system parameters. Taking into account, the incompressibility property of the Vlasov dynamics and the resulting Landau damping, an explicit form for the final stationary distribution attained by the beam is proposed. The distribution is fully self-consistent, presenting no free fitting parameters. The theory is used to predict the relevant beam transport properties, such as the final particle density distribution, the emittance growth, and the fraction of particles that will be expelled to form halo. The theoretical results are compared to the explicit N-particle dynamics simulations, showing a good agreement.

show abstract

Section: Numerical Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Halo formation and emittance growth in the transport of spherically symmetric mismatched bunched beams

et al. 2015

View full text Add to dashboard Cite

show abstract

“…However, the beam quality could still be measured by comparing the number of particles in the core of the beam. This value dropped off dramatically when the settings were not optimized, suggesting a significant beam halo effect [25,30,31]. The plots in Figs.…”

Section: Deuteron Beam Currentmentioning

confidence: 99%

Permanent-magnet quadrupoles for an interdigital H -mode drift tube linear accelerator: Optimization code and adjustable magnet design

Easton

et al. 2018

Phys. Rev. Accel. Beams

View full text Add to dashboard Cite

Magnets to be used for the internal quadrupoles of an interdigital H-mode drift tube linear accelerator (IH-DTL) using KONUS beam dynamics should be both compact in size and high in focusing field gradient. Permanent magnets are an attractive solution, but then the ability to adjust the field strength is lost. We investigated two different solutions to this problem: the first using external adjustable electromagnets; the second using internal adjustable permanent magnets. The first method moves the variability out of the resonant cavity, using adjustable electromagnet quadrupole doublets before entry into the IH-DTL to compensate for the lack of internal variability. We carried out optimization simulations with custom code that ran many instances of the LORASR beam dynamics simulation software, using different values of field strength for the external doublets. By optimizing the magnet settings for different values of input current, we were able to compensate for the space-charge forces involved in accelerating a high-intensity continuous-wave (CW) deuteron beam. Second, we designed some novel adjustable permanent-magnet quadrupoles to be used inside the cavity, which combine the advantages of small cross-section and variable field gradient. This allows much more control over the beam, and even other ion species with differing charge-to-mass ratios can be accommodated within the same accelerator design. We developed two adjustable permanent-magnet designs: one with an electromagnetic component, and the other with two concentric moving rings of Halbach-array quadrupoles.

show abstract

“…Recently, we proposed a precise determination of the corehalo limit (Nghiem et al, 2014b). The idea is to extrapolate from the case of dense uniform core surrounded by a much more tenuous halo (see Fig.…”

Section: Beam Characterizationmentioning

confidence: 99%

Advanced concepts and methods for very high intensity accelerators

et al. 2014

Self Cite

View full text Add to dashboard Cite

For very high intensity accelerators, not only beam power but also space charge is a concern. Both aspects should be taken into consideration for any analysis of accelerators aiming at comparing their performances and pointing out the challenging sections. As high beam power is an issue from the lowest energy, careful and exhaustive beam loss predictions have to be done. High space charge implies lattice compactness making the implementation of beam diagnostics very problematic, so a clear strategy for beam diagnostic has to be defined. Beam halo is no longer negligible. Its dynamics is different from that of the core and plays a significant role in the particle loss process. Therefore, beam optimization must take the halo into account and beam characterization must be able to describe the halo part in addition to the core one. This paper presents the advanced concepts and methods for beam analysis, beam loss prediction, beam optimization, beam diagnostic, and beam characterization especially dedicated to very high intensity accelerators. Examples of application of these concepts are given in the case of the IFMIF accelerators.

show abstract

Core-halo issues for a very high intensity beam

Abstract: New improvements on the Kansas State University cryogenic electron beam ion source, a user facility for low energy, highly charged ions Rev. Sci. Instrum. 71, 902 (2000

Cited by 17 publications

References 12 publications

Halo formation and emittance growth in the transport of spherically symmetric mismatched bunched beams

Halo formation and emittance growth in the transport of spherically symmetric mismatched bunched beams

Permanent-magnet quadrupoles for an interdigital H -mode drift tube linear accelerator: Optimization code and adjustable magnet design

Advanced concepts and methods for very high intensity accelerators

Contact Info

Product

Resources

About