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Title: CBETA Design Report

Abstract

This Design Report describes the baseline design of the Cornell-BNL ERL Test Accelerator, as it exists on the date of its publication in June 2017. The Design Report will not change frequently in the future. In contrast, the parameter sheets that summarize the CBETA design will respond as quickly and as thoroughly as necessary to maintain configuration control.

Authors:
 [1];  [1];  [1]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
OSTI Identifier:
1412725
Report Number(s):
BNL-114549-2017-IR
DOE Contract Number:
SC0012704
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS

Citation Formats

Hoffstaetter, G., Trbojevic, D., and Mayes, C. CBETA Design Report. United States: N. p., 2017. Web. doi:10.2172/1412725.
Hoffstaetter, G., Trbojevic, D., & Mayes, C. CBETA Design Report. United States. doi:10.2172/1412725.
Hoffstaetter, G., Trbojevic, D., and Mayes, C. 2017. "CBETA Design Report". United States. doi:10.2172/1412725. https://www.osti.gov/servlets/purl/1412725.
@article{osti_1412725,
title = {CBETA Design Report},
author = {Hoffstaetter, G. and Trbojevic, D. and Mayes, C.},
abstractNote = {This Design Report describes the baseline design of the Cornell-BNL ERL Test Accelerator, as it exists on the date of its publication in June 2017. The Design Report will not change frequently in the future. In contrast, the parameter sheets that summarize the CBETA design will respond as quickly and as thoroughly as necessary to maintain configuration control.},
doi = {10.2172/1412725},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2017,
month = 6
}

Technical Report:

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  • The splitter/merger section of the CBETA project [1] consists of 4 beam lines as shown in Fig. 1. Two of the functions of the splitter’s/merger’s lines is to match the beam parameters at the exit of the Energy Recovery Linac (ERL) to the beam parameters at the entrance of the Fixed Field Alternating Gradient (FFAG) arc, and also place the reference particles of the beam bunches at the entrance of the FFAG arc on specified trajectories according to their energies. In this technical note we are presenting results from the 2D and 3D electromagnetic analysis of the S4.BEN01 magnet whichmore » is one of the dipole magnets of the 150 MeV line of the splitter/merger. In particular we present results from two designs of the S4.BEN01 magnet, one based on iron dominated current-excited magnet, and the other design based on Halbach-type permanent magnet. An evaluation of the two designs will be given in the section under “conclusion”.« less
  • The Cornell-Brookhaven Energy-Recovery-Linac Test Accelerator (CBETA) will provide a 150-MeV electron beam using four acceleration and four deceleration passes through the Cornell Main Linac Cryomodule housing six 1.3-GHz superconducting RF cavities. The return path of this 76-m-circumference accelerator will be provided by 106 fixed-field alternating-gradient (FFAG) cells which carry the four beams of 42, 78, 114 and 150 MeV. Here we describe magnet designs for the splitter and combiner regions which serve to match the on-axis linac beam to the off-axis beams in the FFAG cells, providing the path-length adjustment necessary to energy recovery for each of the four beams.more » The path lengths of the four beamlines in each of the splitter and combiner regions are designed to be adapted to 1-, 2-, 3-, and 4-pass staged operations. Design specifi- cations and modeling for the 24 dipole and 32 quadrupole electromagnets in each region are presented. The CBETA project will serve as the first demonstration of multi-pass energy recovery using superconducting RF cavities with FFAG cell optics for the return loop.« less
  • This Design Report describes the baseline design of the Cornell-BNL ERL Test Accelerator, as it exists on the date of its publication in June 2017. The Design Report will not change frequently in the future. In contrast, the parameter sheets that summarize the CBETA design will respond as quickly and as thoroughly as necessary to maintain con guration control.
  • A principle of the non-scaling Fixed Field Alternating Gradient (NS-FFAG) is that different energy beam has orbit oscillations Δx around the central circular orbit in both positive and negative direction within a small radial aperture as: Δx=D x*δp/p. For the central circular orbit Δx=0, or for the combined function magnets the field is equal to Bo (B (x) = B o + G* x). The smallest orbit offsets Δx are obtained when the defocusing magnet provides most of the bending for the central energy, while the focusing magnet could be even the regular quadrupole with the central orbit in themore » middle. Stable orbits for a very large energy range [in the case of CBETA this is 4 times in energy], is obtained using opposite polarity magnets producing linear magnetic fields, small dispersion, and very strong focusing.« less
  • The CBETA energy recovery linac uses a single xed eld alternating gradient (FFAG) beam line to return the beam for electron beams with four energies, ranging from 42 MeV to 150 MeV. To keep the beam line compact, the ends of the return line have a small radius of curvature, but the central part of the return line is straight. These are connected by transition lines that adiabatically change from one to the other. We rst describe the design or the arc cell. We then describe how a straight cell is created to be a good match to this arcmore » cell. We then describe the design of the transition line between them. The design process makes use of eld maps for the desired magnets. Because we switch magnet types as we move from the arc, through the transition, and into the straight, there are discrete jumps in the elds that degrade the adiabaticity of the transition, and we describe corrections to manage that.« less