eRHIC Wencan Xu May 1 2019 1 Basic Information Proposal Title Novel Third Harmonic cavity for Full luminosity eRHIC Principal Investigator Wencan Xu DepartmentDivision ColliderAccelerator Department ID: 797633
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Slide1
Novel Third Harmonic Cavity for Full Luminosity eRHIC
Wencan Xu May 1, 2019
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Slide2Basic Information
Proposal Title: Novel Third Harmonic cavity for Full luminosity eRHIC
Principal Investigator: Wencan Xu
Department/Division: Collider-Accelerator Department
Other Investigators: Kevin Smith, Cliff Brutus, Doug Holmes, Mike Blaskiewicz, Tianmu Xin, Binping Xiao, Alex ZaltsmanProposal Term: From - Oct.2019 To – Sept. 2022
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Slide3Project Description: Problem and Idea
3
eRHIC
electron storage ring and other high intensity storage ring requires a third harmonic cavity to improve beam stability by lengthening stored electron bunches and reducing their peak current.
The presence of a gap in high intensity bunch train generates a non-controllable transient beam loading on a traditional TM010 mode SRF cavity, with R/Q ~ 100
Ω
.
To minimize such effect, this LDRD project aims to design a novel TM011 mode third harmonic cavity, to reduce R/Q lower than 1/3 of a typical TM010 SRF cavity, while
E
pk
and
B
pk remain reasonable for 2 MV in a one-cell 1.773 GHz SRF cavity. The challenge of the TM011 mode cavity is that the lower-order-mode (TM010 mode) has to be damped, in addition to the higher-order-modes (HOMs). Geometry optimization to minimize the overlapping between bunch spectrum and cavity modes.On-cell damper (LOM) and beam-pipe absorber (HOM) to damp the full spectrum.
TM010
TM011
Slide44
Parameters
3
rd
harmonic cavity in Current pCDRNew cavity (preliminary result)
Frequency [MHz]
1800
1800
Operating Mode
TM010
TM011
R/Q [Ω]
102
37Epk @ 2MV43.2
19
Bpk
@ 2 MV
94.894
Project Description : Preliminary Proof
The idea for TM011 mode cavity was to trade the cavity geometry volume for R/Q.
Without much optimizing effort, transient beam loading in TM010 cavity induced voltage is more than 50 % of the operating voltage (impossible to control), but only 18% in TM011 cavity (similar with
eRHIC’s
main storage ring cavity, controllable).
TM010
TM011
Slide5Expected Results5
Optimization of TM011 mode third harmonic cavity (including both LOM and HOM damper ) for eRHIC
application
Prototypes of Cu third harmonic cavity, LOM damper and HOM damper for room temperature measurement.
Slide66
Return on Investment
Program: NP
Return on Investment
The third harmonic SRF cavity is a critical component for full luminosity eRHIC, so it is strategic for BNL.The potential for future direct programmatic funding is to apply this concept in other colliders and storage rings involving high bunch charge electron beamsTotal Effort (FTE): This project requires RF physics design and support from mechanical engineer.Scientific: 0.2Post Doc: 0Other: 0.2
Slide7Funding Requirements
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Based on vendor quotes and engineering estimates, total project cost is $331,792
for two
years.
Fiscal
Year
FY2020
FY2021
Total Funds
$106,173
$225,619
Labor
00MST$96,000$204,000Dept. O/H00Lab G&A$10,173$21,619
Slide88
Summary
Third harmonic cavity is a crucial component for full luminosity
eRHIC
.
Transient beam loading in a traditional TM010 mode cavity causes cavity impossible to be controlled.
This LDRD aims to development a novel TM011 cavity with R/Q lower than 1/3 of a typical TM010 SRF cavity, while not compromising other SRF parameters.
The proposed project is strategic for BNL and can be applied to other high intensity colliders and storage rings.
Slide9Backup slides9