IPAC2011 - List of Authors (Tang, J.)

Paper

Title

Page

Courant-Snyder Invariant Density Screening Method for Emittance Analysis

1263

J.L. Sun, H.T. Jing, J. Tang
IHEP Beijing, Beijing, People's Republic of China

The emittance is an important characteristic of describing charged particle beams. In hadron accelerators, we often meet irregular beam distributions that are not appropriate to be described with a single rms or 95% or total emittance. In many cases beam halo should be described with very different Courant-Snyder parameters from the ones for beam core. A new method – Courant-Snyder invariant density screening method is developed for analyzing emittance data clearly and accurately. The method treats emittance data from both measurements and numerical simulations. The method uses the statistical distribution of the beam around each particle in phase space to mark its local density parameter, and then uses the density distribution to calculate the beam parameters such as Courant-Snyder parameters and emittance for different beam boundary definitions. The method has been used in the calculations for the beams from difference sources, and shows its advantages over other methods. An application code based on the method including the graphic interface has also been designed using the Matlab software.

WEPS050

The MEBT Design for the China Accelerator Driven System

2604

H. Geng, H.F. Ouyang, J. Tang
IHEP Beijing, Beijing, People's Republic of China
Z. Li, S. Pei, F. Yan
IHEP Beijng, Beijing, People's Republic of China

The Medium Eneryg Beam Transport (MEBT) line plays an important role in transporting and matching the beam from the RFQ exit to the entrance to the next type of acceleration structures while provides enough beam diagnostics for beam commissing and tuning. The beam dynamics design for the 1GeV China Accelerator Driven System (CADS) is making great progress. In this paper, we will describe the design–both element choosing and beam dynamics study of the 3MeV MEBT for the CADS project.

WEPS098

Combined Momentum Collimation Method in High-intensity Rapid Cycling Proton Synchrotrons

2736

J.F. Chen, J. Tang, Y. Zou
IHEP Beijing, Beijing, People's Republic of China

A new momentum collimation method – so-called combined momentum collimation method in high-intensity synchrotrons is proposed and studied here, which makes use two-stage collimation in both the longitudinal and the transverse phase planes. The primary collimator is placed at a high-dispersion location of an arc, and the longitudinal and transverse secondary collimators are in the same arc and in the down-stream dispersion-free long straight section, respectively. The particles with positive momentum deviations will be scattered and degraded by a carbon scraper and then cleaned mainly by the transverse collimators, whereas the particles with negative momentum deviations will be scattered by a tantalum scraper and mainly cleaned by the longitudinal secondary collimators in the successive turns. Numerical simulation results using TURTLE and ORBIT codes show that this method gives high collimation efficiency for medium-energy synchrotrons. The studies have also shown two interesting effects: one is that the momentum collimation is strongly dependent on the transverse beam correlation; the other is that the material for the primary collimator plays an important role in the method.
This work was supported by the National Natural Science Foundation of China (10975150, 10775153), the CAS Knowledge Innovation Program-“CSNS R&D Studies”.

WEPS099

Physics Design of CSNS RCS Injection and Extraction System

2739

J. Qiu, N. Huang, J. Tang, S. Wang
IHEP Beijing, Beijing, People's Republic of China

In this paper, the injection and extraction system design for CSNS RCS are discussed. The injection system is designed to place all the injection devices in one uninterrupted long drift in one of the four dispersion free straight sections. Painting bumper magnets are used for both horizontal and vertical phase space painting. The beam extraction process from the CSNS RCS is a single turn two step process, requiring a group of kickers and a Lambertson septum magnet.

TUXA01

Status and Challenges of the China Spallation Neutron Source

889

S. Fu, H. Chen, Y.W. Chen, Y.L. Chi, H. Dong, L. Dong, S.X. Fang, K.X. Huang, W. Kang, J. Li, L. Ma, H.F. Ouyang, H. Qu, H. Sun, J. Tang, C.H. Wang, Q.B. Wang, S. Wang, T.G. Xu, Z.X. Xu, X. Yin, C. Zhang, J. Zhang
IHEP Beijing, Beijing, People's Republic of China

The accelerator complex of China Spallation Neutron Source (CSNS) mainly consists of an H⁻ linac of 80 MeV and a rapid-cycling synchrotron of 1.6 GeV. It operates at 25 Hz repetition rate with an initial proton beam power of 100 kW and is upgradeable to 500kW. The project will start construction in the middle of 2011 with a construction period of 6.5 years. The CSNS accelerator is the first large-scale, high-power accelerator project to be constructed in China and thus we are facing a lot of challenges. This paper presents the current status of CSNS project and summarizes the technology development during the past several years.

Slides TUXA01 [3.444 MB]

THPS041

Design of Beam Transport Line from RCS to Target for CSNS

3514

W.B. Liu, N. Huang, J. Qiu, J. Tang, S. Wang, G. Xu
IHEP Beijing, Beijing, People's Republic of China

China Spallation Neutron Source (CSNS) uses the high energy proton beam to strike the Tungsten target to generate neutrons through spallation reaction. The proton beam is extracted from the Rapid Cycling Synchrotron (RCS), whose beam power reaches 100 kW. For the sake of target lifetime, beam distribution at the target surface is required as uniform as possible. Nonlinear beam density redistribution method with two octupole magnets has been studied. Also some simulation and theoretical calculation have been done. According to the simulation result, the beam density at the target is optimized and the beam loss is under control.

Paper	Title	Page
TUPC106	Courant-Snyder Invariant Density Screening Method for Emittance Analysis	1263
	J.L. Sun, H.T. Jing, J. Tang IHEP Beijing, Beijing, People's Republic of China
	The emittance is an important characteristic of describing charged particle beams. In hadron accelerators, we often meet irregular beam distributions that are not appropriate to be described with a single rms or 95% or total emittance. In many cases beam halo should be described with very different Courant-Snyder parameters from the ones for beam core. A new method – Courant-Snyder invariant density screening method is developed for analyzing emittance data clearly and accurately. The method treats emittance data from both measurements and numerical simulations. The method uses the statistical distribution of the beam around each particle in phase space to mark its local density parameter, and then uses the density distribution to calculate the beam parameters such as Courant-Snyder parameters and emittance for different beam boundary definitions. The method has been used in the calculations for the beams from difference sources, and shows its advantages over other methods. An application code based on the method including the graphic interface has also been designed using the Matlab software.

WEPS050	The MEBT Design for the China Accelerator Driven System	2604
	H. Geng, H.F. Ouyang, J. Tang IHEP Beijing, Beijing, People's Republic of China Z. Li, S. Pei, F. Yan IHEP Beijng, Beijing, People's Republic of China
	The Medium Eneryg Beam Transport (MEBT) line plays an important role in transporting and matching the beam from the RFQ exit to the entrance to the next type of acceleration structures while provides enough beam diagnostics for beam commissing and tuning. The beam dynamics design for the 1GeV China Accelerator Driven System (CADS) is making great progress. In this paper, we will describe the design–both element choosing and beam dynamics study of the 3MeV MEBT for the CADS project.

WEPS098	Combined Momentum Collimation Method in High-intensity Rapid Cycling Proton Synchrotrons	2736
	J.F. Chen, J. Tang, Y. Zou IHEP Beijing, Beijing, People's Republic of China
	A new momentum collimation method – so-called combined momentum collimation method in high-intensity synchrotrons is proposed and studied here, which makes use two-stage collimation in both the longitudinal and the transverse phase planes. The primary collimator is placed at a high-dispersion location of an arc, and the longitudinal and transverse secondary collimators are in the same arc and in the down-stream dispersion-free long straight section, respectively. The particles with positive momentum deviations will be scattered and degraded by a carbon scraper and then cleaned mainly by the transverse collimators, whereas the particles with negative momentum deviations will be scattered by a tantalum scraper and mainly cleaned by the longitudinal secondary collimators in the successive turns. Numerical simulation results using TURTLE and ORBIT codes show that this method gives high collimation efficiency for medium-energy synchrotrons. The studies have also shown two interesting effects: one is that the momentum collimation is strongly dependent on the transverse beam correlation; the other is that the material for the primary collimator plays an important role in the method. This work was supported by the National Natural Science Foundation of China (10975150, 10775153), the CAS Knowledge Innovation Program-“CSNS R&D Studies”.

WEPS099	Physics Design of CSNS RCS Injection and Extraction System	2739
	J. Qiu, N. Huang, J. Tang, S. Wang IHEP Beijing, Beijing, People's Republic of China
	In this paper, the injection and extraction system design for CSNS RCS are discussed. The injection system is designed to place all the injection devices in one uninterrupted long drift in one of the four dispersion free straight sections. Painting bumper magnets are used for both horizontal and vertical phase space painting. The beam extraction process from the CSNS RCS is a single turn two step process, requiring a group of kickers and a Lambertson septum magnet.

TUXA01	Status and Challenges of the China Spallation Neutron Source	889
	S. Fu, H. Chen, Y.W. Chen, Y.L. Chi, H. Dong, L. Dong, S.X. Fang, K.X. Huang, W. Kang, J. Li, L. Ma, H.F. Ouyang, H. Qu, H. Sun, J. Tang, C.H. Wang, Q.B. Wang, S. Wang, T.G. Xu, Z.X. Xu, X. Yin, C. Zhang, J. Zhang IHEP Beijing, Beijing, People's Republic of China
	The accelerator complex of China Spallation Neutron Source (CSNS) mainly consists of an H⁻ linac of 80 MeV and a rapid-cycling synchrotron of 1.6 GeV. It operates at 25 Hz repetition rate with an initial proton beam power of 100 kW and is upgradeable to 500kW. The project will start construction in the middle of 2011 with a construction period of 6.5 years. The CSNS accelerator is the first large-scale, high-power accelerator project to be constructed in China and thus we are facing a lot of challenges. This paper presents the current status of CSNS project and summarizes the technology development during the past several years.
	Slides TUXA01 [3.444 MB]

THPS041	Design of Beam Transport Line from RCS to Target for CSNS	3514
	W.B. Liu, N. Huang, J. Qiu, J. Tang, S. Wang, G. Xu IHEP Beijing, Beijing, People's Republic of China
	China Spallation Neutron Source (CSNS) uses the high energy proton beam to strike the Tungsten target to generate neutrons through spallation reaction. The proton beam is extracted from the Rapid Cycling Synchrotron (RCS), whose beam power reaches 100 kW. For the sake of target lifetime, beam distribution at the target surface is required as uniform as possible. Nonlinear beam density redistribution method with two octupole magnets has been studied. Also some simulation and theoretical calculation have been done. According to the simulation result, the beam density at the target is optimized and the beam loss is under control.