srf gun development - cern · final weld development underway cavity completion data 7/09 ...
TRANSCRIPT
![Page 1: SRF GUN DEVELOPMENT - CERN · Final weld development underway Cavity completion data 7/09 Tentative plan to clean and test cavity at JLAB Tooling for string assembly being](https://reader034.vdocuments.us/reader034/viewer/2022042111/5e8bd5a17390a168c44d29f1/html5/thumbnails/1.jpg)
SRF GUN DEVELOPMENT
BNL’S MANY INTERESTS
Andrew Burrill on behalf of the electron cooling group
<#>
Andrew Burrill on behalf of the electron cooling group
Brookhaven National Laboratory
![Page 2: SRF GUN DEVELOPMENT - CERN · Final weld development underway Cavity completion data 7/09 Tentative plan to clean and test cavity at JLAB Tooling for string assembly being](https://reader034.vdocuments.us/reader034/viewer/2022042111/5e8bd5a17390a168c44d29f1/html5/thumbnails/2.jpg)
Agenda
� Review past SRF gun testing at BNL
� Look at programs that have grown from this
work
� Discuss novel cathode insertion design
� Application for high average current
<#>
� Application for high average current
� New Low Frequency SRF gun
� Photocathode transport
� Vacuum requirements, cleanliness, contamination
![Page 3: SRF GUN DEVELOPMENT - CERN · Final weld development underway Cavity completion data 7/09 Tentative plan to clean and test cavity at JLAB Tooling for string assembly being](https://reader034.vdocuments.us/reader034/viewer/2022042111/5e8bd5a17390a168c44d29f1/html5/thumbnails/3.jpg)
703 MHz SRF Gun for ERL
(AES Fabrication)
112 MHz Quarter wave Gun
(Niowave SBIR)
<#><#>
1.3 GHz Bare Nb injector
(AES SBIR/CRADA)
Plug Gun
Choke joint Gun
(AES Fabrication)
(JLAB modification)
![Page 4: SRF GUN DEVELOPMENT - CERN · Final weld development underway Cavity completion data 7/09 Tentative plan to clean and test cavity at JLAB Tooling for string assembly being](https://reader034.vdocuments.us/reader034/viewer/2022042111/5e8bd5a17390a168c44d29f1/html5/thumbnails/4.jpg)
1.3 GHz Injectors
Our First Foray into SRF Gun Work
Goal: To use bare Nb as a cathode
QE 2e-4 at 266 nm in lab
2e-5 in Gun
<#><#>
Testing courtesy of P.
Kneisel (JLAB)
Nb probesAl probes
![Page 5: SRF GUN DEVELOPMENT - CERN · Final weld development underway Cavity completion data 7/09 Tentative plan to clean and test cavity at JLAB Tooling for string assembly being](https://reader034.vdocuments.us/reader034/viewer/2022042111/5e8bd5a17390a168c44d29f1/html5/thumbnails/5.jpg)
1.3 GHz Plug Gun – GaAs Test System
� Gun modified to accept a
simple Nb plug
� Goal: Measure QE and beam
properties of GaAs in SRF gun
� Baseline cavity tests carried out
� Several interesting observation
with the plug inserted and with
GaAs on the plug
<#><#>
![Page 6: SRF GUN DEVELOPMENT - CERN · Final weld development underway Cavity completion data 7/09 Tentative plan to clean and test cavity at JLAB Tooling for string assembly being](https://reader034.vdocuments.us/reader034/viewer/2022042111/5e8bd5a17390a168c44d29f1/html5/thumbnails/6.jpg)
Quarter wave choke jointCavity modified by adding a quarter wavelength choke
Joint for a demountable photocathode
30
40
50
60
70
80
90
100
1.00E+09
1.00E+10
rad
(m
R/h
r)
Qo
BNL_gun1 no cathode
First Pass
Second test after FE event
<#><#>
0
10
20
30
1.00E+08
0 5 10 15 20 25 30 35 40
Epeak (MV/m)
1.00E+08
1.00E+09
1.00E+10
0 1 2 3 4 5
Qo
Epk (MV/m)
Cathode installed
Barrier
Multipacting barrier at low field in choke region
Mitigation plans
1. High Temperature bake – reduced SEY
2. Bias cathode stalk
![Page 7: SRF GUN DEVELOPMENT - CERN · Final weld development underway Cavity completion data 7/09 Tentative plan to clean and test cavity at JLAB Tooling for string assembly being](https://reader034.vdocuments.us/reader034/viewer/2022042111/5e8bd5a17390a168c44d29f1/html5/thumbnails/7.jpg)
SRF Photoinjector at 703.75 MHz
� ½ Cell SRF injector� Demountable cathode
stalk
� High Temperature superconducting Solenoid
<#>
Solenoid
� UHV cathode transporter carts� 2 fabricated and
delivered
� Testing underway
![Page 8: SRF GUN DEVELOPMENT - CERN · Final weld development underway Cavity completion data 7/09 Tentative plan to clean and test cavity at JLAB Tooling for string assembly being](https://reader034.vdocuments.us/reader034/viewer/2022042111/5e8bd5a17390a168c44d29f1/html5/thumbnails/8.jpg)
<#><#>
![Page 9: SRF GUN DEVELOPMENT - CERN · Final weld development underway Cavity completion data 7/09 Tentative plan to clean and test cavity at JLAB Tooling for string assembly being](https://reader034.vdocuments.us/reader034/viewer/2022042111/5e8bd5a17390a168c44d29f1/html5/thumbnails/9.jpg)
High Temperature Superconducting
Solenoid already fabricated
<#><#>
FPC schematic for ½ cell gun
![Page 10: SRF GUN DEVELOPMENT - CERN · Final weld development underway Cavity completion data 7/09 Tentative plan to clean and test cavity at JLAB Tooling for string assembly being](https://reader034.vdocuments.us/reader034/viewer/2022042111/5e8bd5a17390a168c44d29f1/html5/thumbnails/10.jpg)
Injector Fabrication and Cryomodule
Status� Injector fabrication underway at Advanced Energy Systems
� Significant delays caused by ASME pressure vessel code requirements, weld and braze sample preparation
� Choke joint machining finished� Nb VTA cathode fabricated
� Final weld development underway
� Cavity completion data 7/09
<#>
� Cavity completion data 7/09
� Tentative plan to clean and test cavity at JLAB
� Tooling for string assembly being designed and fabricated in-house
� Cryomodule design complete, based on top loading, ballast tank system, similar to Linac cryomodule, going out for bid now.
![Page 11: SRF GUN DEVELOPMENT - CERN · Final weld development underway Cavity completion data 7/09 Tentative plan to clean and test cavity at JLAB Tooling for string assembly being](https://reader034.vdocuments.us/reader034/viewer/2022042111/5e8bd5a17390a168c44d29f1/html5/thumbnails/11.jpg)
VTF Injector Test Plan
� Test injector without cathode stalk� Determine operating conditions for cavity geometry
� Test with VTF cathode stalk inserted� Determine impact of cathode stalk on cavity performance
� Parallel development project with 1.3 GHz choke joint gun, working on high temperature bake of gun and biasing system
� Weld He vessel to gun and re-test
<#>
� Weld He vessel to gun and re-test
� Final chemistry and HPR pass, build into hermetic string in cleanroom
� Transfer to BNL to complete cryomodule assembly� Same group responsible for Linac cryomodule
� Transfer to ERL building for horizontal testing and cathode transporter cart integration
![Page 12: SRF GUN DEVELOPMENT - CERN · Final weld development underway Cavity completion data 7/09 Tentative plan to clean and test cavity at JLAB Tooling for string assembly being](https://reader034.vdocuments.us/reader034/viewer/2022042111/5e8bd5a17390a168c44d29f1/html5/thumbnails/12.jpg)
Injector Fundamental Power Couplers
� 2X 500 kW CW coaxial couplers
with “Pringle tip” designed and
fabricated at CPI
� In house, awaiting completion of
resonant waveguide for conditioning
� BNL will condition FPCs with our 1
<#>
� BNL will condition FPCs with our 1
MW Klystron
� Additional project with AES to test
legacy couplers to failure
![Page 13: SRF GUN DEVELOPMENT - CERN · Final weld development underway Cavity completion data 7/09 Tentative plan to clean and test cavity at JLAB Tooling for string assembly being](https://reader034.vdocuments.us/reader034/viewer/2022042111/5e8bd5a17390a168c44d29f1/html5/thumbnails/13.jpg)
Fundamental Power Coupler conditioning
� 2X 500 kW RF couplers
built for 703 MHz injector
� Plan to condition couplers at
BNL using 1 MW klystron
� Will also test spare AES Mark
II couplers to performance
limit
<#>
limit
� Designed for 350 kW
operation, will push to failure
![Page 14: SRF GUN DEVELOPMENT - CERN · Final weld development underway Cavity completion data 7/09 Tentative plan to clean and test cavity at JLAB Tooling for string assembly being](https://reader034.vdocuments.us/reader034/viewer/2022042111/5e8bd5a17390a168c44d29f1/html5/thumbnails/14.jpg)
112 MHz Injector
SBIR proof of principle design
Applications for low energy electron cooling
Demonstration of 4K gun technology
Frequency (MHz) 112.5978
Vo (MeV, beta=<0.98>) 2.7
Ecathode (MV/m) 19.67
Eo (MV/m) 28.28
Epeak (MV/m) 51.29
Bpeak (mT) 97.83
Bp/Ep (mT/(MV/m)) 1.91
Pd (W) 16.55
T (K) 4.5
Q 3.48e9
G (Ohm) 38.25
R/Q (Ohm) 126.77
<#><#>
R/Q (Ohm) 126.77
TTF 0.99
![Page 15: SRF GUN DEVELOPMENT - CERN · Final weld development underway Cavity completion data 7/09 Tentative plan to clean and test cavity at JLAB Tooling for string assembly being](https://reader034.vdocuments.us/reader034/viewer/2022042111/5e8bd5a17390a168c44d29f1/html5/thumbnails/15.jpg)
� Beer can laser size: R=5.5mm, L=11.0 deg(270ps, 8.14cm full length)
� 5nC/bunch
� Energy at gun exit and linac exit: 2.69MeV, 19.1MeV
112MHz
Gun
112MHz
Cavity
20cm 30cm 70cm 80cm5cm 160cm
Solenoids
0.455 nC Case
Work by X. Chang
<#><#>
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Em
itta
nc
e (
cm
.mr)
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0 100 200 300 400 500 600
Z (cm)
Em
itta
nce (
cm
.mr)
5 nC Case2nC Case
![Page 16: SRF GUN DEVELOPMENT - CERN · Final weld development underway Cavity completion data 7/09 Tentative plan to clean and test cavity at JLAB Tooling for string assembly being](https://reader034.vdocuments.us/reader034/viewer/2022042111/5e8bd5a17390a168c44d29f1/html5/thumbnails/16.jpg)
CsK2Sb Photocathode
� Deposition System in
house� 2 transporter carts delivered
� Base pressure 1x10-10 Torr
� System designed to eliminate
cross contamination of sources
<#>
cross contamination of sources
� Provides for quicker source
exchange
� Transporter cart
� 2 UHV systems with LN2 cooling
capability
� Awaiting replacement
thermocouple prior to re-bake
![Page 17: SRF GUN DEVELOPMENT - CERN · Final weld development underway Cavity completion data 7/09 Tentative plan to clean and test cavity at JLAB Tooling for string assembly being](https://reader034.vdocuments.us/reader034/viewer/2022042111/5e8bd5a17390a168c44d29f1/html5/thumbnails/17.jpg)
Laser System
� Lumera built a 5 W, 355 nm, 10 ps, 9.38 MHz
laser system
� Designed for BNL needs for generation of 50 mA current
� We had discussions with vendor about upgrading to
system for 500 mA if funding is available
� Will be operated at 532nm, 355nm, and 266nm
<#>
� Will be operated at 532nm, 355nm, and 266nm
� Active program for generation of spatial and temporal flat
top beams underway with good progress
� System arrived 2 weeks ago, and installation and field
testing is complete and met most expectation.
Contact: Triveni Rao