Higher order mode beams mitigate halos in high intensity proton linacs

Pathak, Abhishek; Krishnagopal, S.

doi:10.1103/physrevaccelbeams.20.014201

Cited by 3 publications

(4 citation statements)

References 33 publications

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“…A mismatch value of Mismatch 𝑥 on the (𝑥, 𝑥 ) projection for the 𝛼 𝑥 (𝑠) and 𝛽 𝑥 (𝑠) parameters is represented as [26] 𝛼 𝑚𝑥 (𝑠) = (1 + Mismatch 𝑥 ) 2 × 𝛼 𝑥 (𝑠), where 𝛼 𝑚𝑥 (𝑠) and 𝛽 𝑚𝑥 (𝑠) are the mismatching Twiss parameters. The mismatch is defined to be similar in the other planes by replacing 𝑥 for 𝑦 or 𝑧.…”

Section: Mismatchmentioning

confidence: 99%

Beam physics design of a 30-MW beam transport to the target for an accelerator-driven subcritical system

et al. 2022

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The Japan Atomic Energy Agency's accelerator-driven subcritical system (JAEA-ADS) proposes the reduction of nuclear waste through the transmutation of minor actinides. The JAEA-ADS drives a 30-MW proton beam to a spallation target to produce neutrons for a subcritical 800-MWth reactor. The beam must be transported from the end of the linear accelerator (linac) to the target located inside the reactor core with high beam power stability and low peak density to ensure beam window integrity, which is a primary concern for the ADS project. Additionally, the design of the beam transport to the target (BTT) must be compatible with the established reactor design, and the elements that comprise the BTT must facilitate the maintenance and replacement of the fuel and the beam window. To this end, a robust-compact BTT design was developed through massive multiparticle simulations. First, the beam optics was optimized to guarantee beam window feasibility requirements by providing a low peak density of less than 0.3 μA/mm2. Then, beam stability was evaluated and improved by a simultaneous application of input beam and element errors. The input beam errors were based on the beam degradation obtained by implementing fast fault compensation in the linac, which is a key strategy to attain high-reliability operation. The results show that the BTT design fulfills reactor and beam window requirements for JAEA-ADS.

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Section: Mismatchmentioning

confidence: 99%

Beam physics design of a 30-MW beam transport to the target for an accelerator-driven subcritical system

et al. 2022

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“…The background contour plot corresponds to the level contours of Hamiltonian (1). Yellow curves are given by the approximate anharmoinc solution (5), for oscillation amplitudes of ∆ = 0.1, 0.2, 0.3, and 0.4. In the considered range of parameter space, equation ( 5) provides an adequate approximation for the phase-space portrait of Hamiltonian (1).…”

Section: A Pulsation Of the Corementioning

confidence: 99%

“…Fundamentally, this propensity towards reemergence indicates that intrinsic self-excitation of the beam through non-linear space-charge forces plays an appreciable, if not dominant, role in the process of halo formation 9,10 . In this vein, one potential suppression mechanism for beam halo formation employs nonlinear focusing, as originally proposed in 2,3 and further developed in 4,5 . Nevertheless, a detailed understanding of this halo-formation mechanism remains incomplete, and constitutes an active area of investigation [11][12][13][14] .…”

Section: Introductionmentioning

confidence: 99%

Chaotic dynamics driven by particle-core interactions

Batygin

2021

Physics of Plasmas

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High-intensity beams in modern linacs are frequently encircled by diffuse halos, which drive sustained particle losses and result in the gradual degradation of accelerating structures. In large part, the growth of halos is facilitated by internal space-charge forces within the beams, and detailed characterization of this process constitutes an active area of ongoing research. A partial understanding of dynamics that ensue within space-charge dominated beams is presented by the particle-core interaction paradigm—a mathematical model wherein single particle dynamics, subject to the collective potential of the core, is treated as a proxy for the broader behavior of the beam. In this work, we investigate the conditions for the onset of large-scale chaos within the framework of this model and demonstrate that the propensity toward stochastic evolution is strongly dependent upon the charge distribution of the beam. In particular, we show that while particle motion within a uniformly charged beam is dominantly regular, rapid deterministic chaos readily arises within space-charge dominated Gaussian beams. Importantly, we find that for sufficiently high values of the beam's space charge and beam pulsation amplitude, enhanced chaotic mixing between the core and the halo can lead to an enhanced radial diffusion of charged particles. We explain our results from analytic grounds by demonstrating that chaotic motion is driven by the intersection of two principal resonances of the system and derives the relevant overlap conditions. Additionally, our analysis illuminates a close connection between the mathematical formulation of the particle-core interaction model and the Andoyer family of integrable Hamiltonians.

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“…Fast losses are primarily caused by failure of accelerator components, thus they are unexpected and occur instantaneously. By contrast, slow losses primarily arise because of intrinsic beam transport characteristics, such as formation of the beam halo from nonlinear space charge effects [7][8][9], which are rather expected and occur slowly (these typically accumulate over 100 ms). The lost particles can collide with and be injected into the surface of the beam pipe, which causes serious damage to beam line components (see figure 2).…”

Section: Introductionmentioning

confidence: 99%

Design study of Beam Loss Monitoring system for the Rare Isotope Science Project in Korea

et al. 2019

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A: A new heavy ion accelerator facility called RAON is being constructed in Daejeon, Korea to produce rare isotope beams of various energies for the Rare Isotope Science Project (RISP). This facility is designed to use both the In-flight Fragmentation (IF) and Isotope Separation On-Line (ISOL) systems to provide a wide range of rare isotope beams to be utilized in many fundamental physics experiments and in various applications. The RAON can use both stable heavy ion beams and rare isotope beams with energies up to a few hundreds of MeV/u with 400 kW of beam power. One of the greatest challenges in operating such a high beam power facility (∼ 400 kW) is to accurately monitor the beam loss and trigger the Machine Protection System (MPS) reasonably quickly. In this paper, we report the conceptual design of the RAON beam loss monitoring system. Monte Carlo simulations using the MCNPX code were performed to understand beam loss-induced neutron and gamma radiation. The types of detectors were determined based on radiation simulations while considering the sensitivities of the detectors and response time requirements. K: Detector modelling and simulations I (interaction of radiation with matter, interaction of photons with matter, interaction of hadrons with matter, etc); Interaction of radiation with matter; Neutron detectors (cold, thermal, fast neutrons); Very low-energy charged particle detectors 1Corresponding author.

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Higher order mode beams mitigate halos in high intensity proton linacs

Cited by 3 publications

References 33 publications

Beam physics design of a 30-MW beam transport to the target for an accelerator-driven subcritical system

Beam physics design of a 30-MW beam transport to the target for an accelerator-driven subcritical system

Chaotic dynamics driven by particle-core interactions

Design study of Beam Loss Monitoring system for the Rare Isotope Science Project in Korea

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