Summary of the RF Parallel Session
MICE Collaboration Meeting 18
June 16, 2007
Steve Virostek
Lawrence Berkeley National Lab
RF Session Talks
MuCool RF Program: RF Cavity R & D
(A. Bross)
RFCC Module Design Update
(S. Virostek)
Coupling Coil Integration with the RFCC Module
(S. Virostek)
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 2
MuCool RF Program:
RF Cavity R & D
805 and 201 MHz Studies
ANL / FNAL / IIT / LBNL
U Miss / Cockcroft
MICE Collaboration Meeting 18
June 13, 2007
Alan Bross
MuCool Test Area
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 4
MuCool Test Area
• Facility to test all components of cooling channel
(not a test of ionization cooling)
– At high beam power
• Designed to accommodate full Linac Beam
• 1.6 X 1013 p/pulse @15 Hz
– 2.4 X 1014 p/s
–  600 W into 35 cm LH2 absorber @ 400 MeV
– RF power from Linac (201 and 805 MHz test stands)
• Waveguides pipe power to MTA
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 5
MTA Hall
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 6
805 MHz
• Data seem to follow
universal curve
– Max stable gradient degrades
quickly with B field
• Remeasured
Gradient in MV/m
– Same results
– Does not condition
Peak Magnetic Field in T at the Window
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 7
805 MHz Imaging
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 8
805 MHz Sparking Damage Curved Be Window after
Processing in Magnet Field
Small amount of sparking damage on upstream window at 12 o’clock (least damage seen in
Studies). Cavity bright & clean. Damage on copper iris is mainly from previous testing.
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 9
Next 805 MHz study - Buttons
Button test
– Evaluate various materials and coatings
– Quick change over
Field Profile
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 10
First Set of Button Data – TiN Coated Cu
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 11
TiN Coated Cu – After Running
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 12
RF R&D – 201 MHz Cavity Design
• The 201 MHz Cavity is now operating
– New x-ray background data collected (see Alan’s talk)
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 13
201 MHz Cavity Status
• The flat Cu windows have been replaced w/curved Be windows
• Slower conditioning and more sparking than with the Cu. May
be due to better clean room at J-Lab during initial installation.
– However, MTA CR air quality was measured at class 100 or better
• So far the 201 w/Be windows has been conditioned to ~5MV/m
• No running for >3 weeks due to 201 power source problems
– Note: The cavity is now out of tune (beyond the range of power
source) and must be re-tuned via the jacking screws
– Cavity frequency dropped ~400 kHz w/curved Be windows installed
– Will get help @Fermilab from LBNL to do the tuning
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 14
Clean Room for 201MHz Cavity
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 15
201 MHz Sparking Damage on Flat Copper Window
coated with TiN over center portion
The inside of the cavity
appeared bright & clean
•Very little spark damage after RF
processing to 18 MV/m
•One copper splatter visible (photo)
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 16
Curved Be window Installation
Tyvek-wrapped Mike
Dickinson and Ben
Ogert installing one
of the Be windows
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 17
Plans for the MTA
• Continue 805 MHz button tests w/bare & TiN coated buttons
• We have buttons made with the following metals
–
–
–
–
–
–
Tantalum
Tungsten
Molybdenum-zirconium alloy
Niobium
Niobium-titanium alloy
Stainless steel
• Continue conditioning 201 with Be windows (if power ever
becomes available) without B field (after re-tuning).
– Then do B field scan
• Can go up to few hundred gauss at present
• Need new pumping system to go higher
• And eventually Coupling Coil
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 18
Coupling Coil Layout in the MTA
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 19
RFCC Module Design Update

automatic tuners

cavity suspension

cavity installation
MICE Collaboration Meeting 18
June 13, 2007
Steve Virostek
Lawrence Berkeley National Lab
RF Cavity & Coupling Coil Modules in MICE
RFCC Modules
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 21
Updated RFCC Module 3D CAD Model
Cavity suspension
Automatic tuners
201 MHz RF cavity
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 22
Cavity Tuner Design Features
•Six evenly spaced automatic
tuners per cavity provide
frequency adjustment
•Layout avoids interference
with cavity ports
•Tuners touch cavity and
apply loads only at the
stiffener rings
•Tuners operate in “push”
mode only (i.e. squeezing)
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 23
Four Cavity Layout in Vacuum Vessel
•Tuner layout rotated
30º @ cavity pairs
•Actuators are off
cavity center plane to
avoid coupling coil
•Bellows connections
at vacuum vessel
feedthroughs
•0 to -460 kHz tuning
range (0 to -4 mm)
•1.6 MPa max. actuator
pressure (50 mm)
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 24
Cavity Tuner Section View
Tuner actuator
(likely air)
Dual bellows
feedthrough
Pivot point
Fixed (bolted)
connection
Ball contact only
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 25
Tuner component Details
Actuator
& bellows
assembly
Pivoting arm
Fixed arm
Forces are transmitted to the stiffener ring
by means of “push/pull” loads applied to the
tuner lever arms by the actuator assembly
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 26
Cavity Suspension System
•Six strut system
provides kinematic
cavity support
•Orthogonal strut
layout is stiff and
allows accurate
cavity positioning
•Kinematic mounts fix
cavity without overconstraint
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 27
Cavity Suspension System
1 vertical strut
3 axial struts
2 horizontal struts
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 28
Strut End Connection Details
The cavity end of the
vertical and one of
the horizontal struts
are attached directly
to the stiffener ring
The cavity end of the
axial and one of the
horizontal struts are
attached to the fixed
leg of a tuner
One end of the struts is attached to a fixed
lug welded to the ID of the vacuum vessel
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 29
Four Cavity Layout in Vacuum Vessel
•Dedicated struts (6)
for each cavity
•No contact between
cavity pairs
•Struts axially fix the
outside walls of the
cavity pairs
•Tuning deflections
increase cavity gap
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 30
Cavity Installation Sequence
•Pre-assemble cavities with Be windows and
tuners (w/o actuators)
•Slide inner cavities into vacuum vessel using
spacer/alignment blocks
•Shim cavity to align tuner & coupler vacuum
feedthrus with tuner mounts and cavity ports
•Install struts, tuner actuators and RF couplers
•Repeat same process for outer cavities
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 31
Coupling Coil Integration
with the RFCC Module
MICE Collaboration Meeting 18
June 13, 2007
Steve Virostek
Lawrence Berkeley National Lab
Coupling Coil Integration Topics
•New coupling coil design developed by LBNL &
ICST (Harbin)
•Increased coil length (+35 mm to 285 mm) results
in longer vacuum vessel
•Integration issues w/tuners and RF, vacuum &
diagnostic cavity ports
•Must transmit magnetic forces from the cold mass
supports to the vacuum vessel
•New 3D model developed by LBNL for integration
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 33
Coupling Coil Design Configuration
Cryocoolers
Cold mass
supports
Support
cone
Service
tower
He cooling pipes
Reinforcing
plates
Indented
sections
Coil assembly
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 34
Coupling Coil Gusset Connections
Gussets between cold mass
support cones and vacuum
shell transmit magnetic forces
Tuner actuators nest
between gussets
Upper Cold Mass Support Cones
Weld
Weld
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 36
Connection to Support Side Plate
Tuner
cutout
Support stand
side plate
Weld
Interior gusset
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 37
Vacuum Vessel Assembly to Coil
Vacuum weld
on interior
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 38
RF Coupler/Coil Interface
Coupler vacuum
sleeve nests in coil
vacuum shell recess
(3 mm gap)
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 39
Vacuum System/Coil Interface
Vacuum manifold
Gate valve
Vacuum pump
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 40
Vacuum System Integration
Inside cavity
vacuum connection
Vacuum
manifold
Outside cavity
vacuum connection
Gate valve
Vacuum pump
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 41
Vacuum Manifold/Coil Interface
Vacuum manifold
end nests in coil
vacuum shell recess
(3 mm gap)
Summary of the RF Parallel Session Talks from MICE CM18
Steve Virostek - Lawrence Berkeley National Lab
Page 42