IPAC2019 - List of Authors (Harada, H.)

Paper	Title	Page
MOPGW037	Dynamic Variation of Chromaticity for Beam Instability Mitigation in the 3-GeV RCS of J-PARC	171
	P.K. Saha, H. Harada, H. Hotchi, Y. Shobuda, T. Takayanagi, F. Tamura, Y. Watanabe JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	We have studied many other dynamic approaches from that reported in the IPAC 2018 for transverse beam instability mitigation in the presence of strong space charge in the 3-GeV RCS of J-PARC. One of such a method is the introduction of an excess of chromaticity from that of natural chromaticity by reversing the sextupole magnetic fields from the middle of the acceleration cycle. The benifits of this method are twofold. It allows to utilize sextupole for chromaticty correction at lower energy and also mitigate the beam instability at higher energy because of introducing higher chromaticity. We first carried out numerical simulations by using ORBIT code, experimentally verified and then applied for the machine operation. The detail of simulation and measurements results are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW037
About •	paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTS033	J-PARC RCS: High-Order Field Components Inherent in the Injection Bump Magnets and Their Effects on the Circulating Beam During Multi-Turn Injection	2009
	H. Hotchi, H. Harada, T. Takayanagi JAEA/J-PARC, Tokai-mura, Japan
	The J-PARC RCS utilizes four sets of pulsed dipole magnets for the formation of injection orbit bump. The injection bump magnets have a large aspect ratio (gap length/core length), so there are other high-order field components inherent in their magnetic fields in addition to the main dipole component. The high-order field components, which locally exist in the injection section not following the lattice super-periodicity, have a significant influence on the circulating beam during multi-turn injection via the excitation of high-order random betatron resonances. This paper discusses the detailed mechanism of emittance growth and beam loss caused by the high-order field components of the injection bump magnets including its correction scenario on the basis of numerical simulation and experimental results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS033
About •	paper received ※ 18 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Dynamic Variation of Chromaticity for Beam Instability Mitigation in the 3-GeV RCS of J-PARC

171

P.K. Saha, H. Harada, H. Hotchi, Y. Shobuda, T. Takayanagi, F. Tamura, Y. Watanabe
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

We have studied many other dynamic approaches from that reported in the IPAC 2018 for transverse beam instability mitigation in the presence of strong space charge in the 3-GeV RCS of J-PARC. One of such a method is the introduction of an excess of chromaticity from that of natural chromaticity by reversing the sextupole magnetic fields from the middle of the acceleration cycle. The benifits of this method are twofold. It allows to utilize sextupole for chromaticty correction at lower energy and also mitigate the beam instability at higher energy because of introducing higher chromaticity. We first carried out numerical simulations by using ORBIT code, experimentally verified and then applied for the machine operation. The detail of simulation and measurements results are presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW037

About •

paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTS033

J-PARC RCS: High-Order Field Components Inherent in the Injection Bump Magnets and Their Effects on the Circulating Beam During Multi-Turn Injection

2009

H. Hotchi, H. Harada, T. Takayanagi
JAEA/J-PARC, Tokai-mura, Japan

The J-PARC RCS utilizes four sets of pulsed dipole magnets for the formation of injection orbit bump. The injection bump magnets have a large aspect ratio (gap length/core length), so there are other high-order field components inherent in their magnetic fields in addition to the main dipole component. The high-order field components, which locally exist in the injection section not following the lattice super-periodicity, have a significant influence on the circulating beam during multi-turn injection via the excitation of high-order random betatron resonances. This paper discusses the detailed mechanism of emittance growth and beam loss caused by the high-order field components of the injection bump magnets including its correction scenario on the basis of numerical simulation and experimental results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS033

About •

paper received ※ 18 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)