P McIntosh STFC Daresbury Laboratory Activities Daresbury SRF for PIPII 352650MHz Cavity Preparation amp Testing HPR BCP 15m diameter cryostat 150W 2K liquefier Cryomodule ID: 791454
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Slide1
Developing the Collaboration
P McIntosh
STFC
Daresbury
Laboratory
Slide2Activities @ Daresbury
SRF (for
PIP-II):
352/650MHz Cavity Preparation & Testing:
HPR
BCP
1.5m diameter cryostat
150W 2K liquefier
Cryomodule
Integration:
6 x 4.9m ISO 4 (Class 10 cleanroom)
Cavity testing post ESS high-beta cavity delivery by end 2020 and
CM integration post HL-LHC crab pre-series CM delivery end 2019
Electron-Cloud SEY
(triggered by Eric’s talk yesterday re: PIP-III main
injector):
Laser processing of beam vessels to reduce SEY to <0.8
Collaboration underway with CERN for HL-LHC and FCC
Slide3ESS High-Beta (0.86) Cavities
STFC requested to procure and test all high-
β
SRF elliptical cavities:
Nb
procurement
Dressed cavity fabrication with industry
Vertical tests
Shipment to CEA
Saclay
Total of 84 dressed 704 MHz cavities:
Plus 4 possible spares.
Operating specification:
20 MV/m @
Q
o
> 5 x 10
9
Testing specification:
23.9 MV/m @
Q
o
> 5 x 10
9
Testing rate of ~1 cavity/week
Slide4SRF Hall/Cleanroom
L
ayout
BCP not included in ESS scope
Slide5HL-LHC Pre-Series CM
Design pre-series CM
CM construction & integration @ DL
SM18 cold tests @ CERN
Slide6Laser treatment of metals in air or noble gas atmosphere
Copper Stainless Steel
N
ew Technology for SEY Reduction
Laser Induced Micro/Nano Structure Surfaces (LIMNSS)
6
Slide7Advantages Over Other M
ethods
7
There
is no need for vacuum or clean room facilities.
The laser is capable of fabricating the desired micro/nanostructure in a single step process.
Hierarchical structures containing both micro- and nanostructures can be created in a single machining step
Machining is performed through a beam of light and thus contactless.
The
process is applicable to the surfaces of any 3D object.
Many parameters can be easily adjusted resulting in a great variety of possible structures.
It is possible to lase in many different environments, such as gases, liquids, or in a
vacuum.
Slide8First results on SEY Reduction
as a function of incident electron energy
Untreated
Laser treated
Original data June 2014
Valizadeh et al. Applied
Physics
Letters 12/2014
; 105(23):
231605
And STFC Patent
8
Copper
Stainless-Steel
Aluminium
Slide9δ
max
as a function of electron dose
for Al, 306L SS
and Cu
9
Sample
Initial
After conditioning to
Q
max
δ
max
E
max
(eV)
δ
max
E
max
(eV)
Q
max
(Cmm-2)
Black Cu1.12600
0.786003.510
-3Black SS1.12
900
0.769001.7
10-2Black Al
1.45
900
0.76
600
2.0
10
-2
Cu
1.90
300
1.25
200
1.0
10
-2
SS
2.25
300
1.22
200
1.7
10
-2
Al
2.55
300
1.34
200
1.5
10
-2
Reduction of
δ
max
after conditioning is attributed to change in surface chemistry due to electron-beam induced transformation of
CuO
to sub-stoichiometric oxide, and build-up of a thin graphite C‐C bonding layer on the surface.
Slide10Surface
resistance measurements
10
Test cavities (3.9 and 7.8 GHz):
The
simulation results obtained with Microwave StudioFabricated from Al.Samples: a 100-mm diam. disk
Bulk Cu5-m thick deposited Cu on Si waferType A on copperType C on copper
Slide117.8
GHz Surface Resistance Measurements
11
Bulk
Roughness
for 7.8 GHz
SampleR (m)
r.m.s. RA (m)
Rs calc
(
m
)
R
s
meas
(
m
)
Cu bulk
1.68
10-8
4.09 10-7
2.8610
-2
2.7010-2Cu(5m)/Si
1.6810-89.08 10-9
2.2710-22.84
10-2LIMNSS-I on Cu1.68
10
-8--
5.910
-2
Al bulk
2.8210
-8
4.05
10
-7
3.40
10
-2
3.85
10
-2
Nb
bulk
1.54
10
-7
(1.0
10
-6
)
8.06
10
-2
6.75
10
-2
304-L
7.2
10
-7
1.44
10
-6
1.60
10
-1
1.6810
-1
Slide12What else do we need to know about LIMNSS?
SEY
in
magnetic fields
0.02T < B > 1T SEY at cryogenic temperatures (relevant for HL-LHC and FCC)Photo-electron emission yield (PEY):
PEY in a magnetic field:requires an access to a SR beamline
12
Slide13Testing At CERN for HL-LHC
Liner has been prepared by STFC
ASTeC
Vacuum
Science group for e-cloud test in SPS at CERN in Jan 16
13
Note:
We are also looking for further test opportunities in Other Particle Accelerators
Slide14E-cloud Mitigation in EuroCirCol
EuroCirCol
is a H2020 program for FCC studies.
WP4 includes e-cloud mitigation studies in FCC (led by STFC ASTeC).Started in June 2015 for 4-years.Collaboration with CERN, ANKA, ELBA and INFN.
14