Two-parameter model for optimizing target beam distribution with an octupole magnet

Meigo, Shinichiro; Oi, Motoki; Fujimori, Hiroshi*

Physical Review Accelerators and Beams (Internet), 23(6), p.062802_1 - 062802_24, 2020/06

https://doi.org/10.1103/PhysRevAccelBeams.23.062802

As hadron accelerators for such as the ADS and spallation neutron source achieve increasing beam power, damage to targets is becoming increasingly severe. To mitigate this damage, nonlinear beam optics based on octupole magnets is attractive. Nonlinear optics can decrease the beam-focusing hazard due to failure of the rastering magnet. As a side effect of nonlinear optics, the beam size is known to expand drastically compared with linear optics. Nonlinear effects have been studied via a simplified filament model that ignores beam-divergence spread at the octupole magnet. In this study, a new generalized model is proposed for application to an octupole magnet, regardless of the filament-model approximation. It is found that the transverse distribution obtained by beam tracking can be specified by the introduction of only two parameters, namely the normalized octupole strength of and the of the phase advance. To achieve the two antagonistic requirements of reduction of the beam-peak density and minimization of the beam loss, the transverse distribution is surveyed for a large range of beam position. It is found that a bell-shaped distribution with 1 and 3 can satisfy requirements. This result is applied to beam transport in the spallation neutron source at J-PARC. The calculation result given by the present model shows good agreement with the experimental data, and the peak current density is reduced by 50% compared with the linear-optics case.

None

Okubo, Hiroo*

JNC TJ1400 99-008, 77 Pages, 1999/02

JNC-TJ1400-99-008.pdf:1.82MB

no abstracts in English

The Inverse estimation of current distribution using combination method of GA and neural-network

Kishimoto, Maki; Sakasai, Kaoru; Ara, Katsuyuki

MAG-93-167, p.17 - 34, 1993/09

no abstracts in English

The Application of genetic algorithms to inverse problems in electron magnetics

Kishimoto, Maki; Sakasai, Kaoru; Ara, Katsuyuki

MAG-92-235, p.83 - 96, 1992/11

no abstracts in English

Development of an optimization analysis sequence OPAS and its application to the prediction models for radioactive cesium distribution

Suzuki, Tadakazu*; Sugita, Takeshi*; Kinase, Sakae; Kurikami, Hiroshi; Kitamura, Akihiro

no journal, , 

An optimization analysis sequence OPAS was developed and applied to prediction models for radioactive cesium distribution. The method and results will be presented.