Status of 201 MHz Prototype Cavity and Curved Be Windows
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Status of 201 MHz Status of 201 MHz Prototype Cavity Prototype Cavity and Curved Be Windows and Curved Be Windows Derun Li Center for Beam Physics Lawrence Berkeley National Laboratory MICE Collaboration Meeting at CERN March 28 – April 1, 2004
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Status of 201 MHz Prototype Cavity and Curved Be Windows. Derun Li Center for Beam Physics Lawrence Berkeley National Laboratory MICE Collaboration Meeting at CERN March 28 – April 1, 2004. Collaborators. R. MacGill J. Staples, S. Virostek, M. Zisman - PowerPoint PPT Presentation
Transcript of Status of 201 MHz Prototype Cavity and Curved Be Windows
Status of 201 MHz Prototype Cavity Status of 201 MHz Prototype Cavity and Curved Be Windows and Curved Be Windows
Derun Li
Center for Beam PhysicsLawrence Berkeley National Laboratory
MICE Collaboration Meeting at CERNMarch 28 – April 1, 2004
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 2
Collaborators
R. MacGill J. Staples, S. Virostek, M. Zisman Lawrence Berkeley National Laboratory, USA
R. Rimmer, L. Philips, G. Wu
Thomas Jefferson Laboratory, USA
W. Lau, S. Yang
Dept. of Physics, Oxford University, UK
D. Summers, M. Reep
Mississippi University, Oxford, MS, USA
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 3
The Cavity Design Update
Cavity profile design was last updated last summer and with considerations of – Low ratio of acceleration field versus peak surface field (~ 1.04)– Numerical simulations with MAFIA, URMEL, SUPERFISH and
ANSYS (RF, thermal and mechanical) codes– Simple (easier) fabrication without losing the performance– Cavity is ready for e-beam welding at JLab now– De-mountable window design allow for other windows and grids
> Baseline window design: curved thin(ner) Be windows (S. Yang’s talk)– Four larger (~4”) ports will be extruded: two for loop couplers,
one for vacuum and one extra– Two smaller ports for probes– Mechanical tuners similar to the ones used in SCRF cavities, and
will be developed very soon The cavity will be ready for high power test this fall
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 4
Brief Review: Cavity Concept
Spinning of half shells and e-beam welding
Water coolingchannels
Cavity design accommodatesdifferent windows
Extruding ports
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 5
The Cavity Profile update
De-mountable Pre-curved Be windows to terminate RF fields at the iris
2o tilt angle
Spherical section at the equator to ease addition of ports (± ~ 6o)Elliptical-like (two circles) nose to reduce peak surface field
6-mm Cu sheet allows for uses ofspinning technique and mechanical tuners
Stiffener ring
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 6
The Cavity Profile update (cont’d)
• RF/Coupling coil module layout• Details of the cavity profile• Ports for couplers and vacuum• Curved Be windows• Ports extruding
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 7
The Cavity Parameters
The cavity design parameters The cavity design parameters – Frequency: 201.25 MHzFrequency: 201.25 MHz– ββ = 0.87 = 0.87– Shunt impedance (VShunt impedance (VTT
22/P): ~ 22 MΩ/m/P): ~ 22 MΩ/m– Quality factor (QQuality factor (Q00): ~ 53,000): ~ 53,000– Curved Be window radius and thickness: 21-cm and 0.38-Curved Be window radius and thickness: 21-cm and 0.38-
mmmm
Nominal parameters for cooling channels in a muon collider or a neutrino factory and MICE– 16+/8 MV/m peak accelerating field– Peak input RF power ~ 4.6/1 MW per cavity (85% of Q0, 3τ
filling)– Average power dissipation per cavity ~ 8.4/1 kW – Average power dissipation per Be window ~ 100/12 watts
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 8
The 201 MHz Cavity R&D
Pleasant and effective collaboration between national labs and universities, a short summary of activities: Cavity design and engineered at LBNL Curved Be window design and engineering at LBNL and
Oxford University Cavity half-shells spun at ACME, a company in Minnesota Nose pieces, stiffener rings and fixturing made at University
of Mississippi and LBNL E-beam welding, cavity cleaning and ports extruding at JLab Design and engineering of RF loop couplers at LBNL SNS RF windows
Weekly video conference with Jlab, daily updates recently while preparing for the equator welding
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 9
Spinning @ ACME
Spinning a bowl
Spinning tools
An example of the spinning technique !
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 10
A Spun Half Shell @ ACME
August 6, 2003
Inner surface scratch was found after chemicalcleaning at JLab, and need to be mechanicallybuffed and electro-polishing.
Can be avoided by carefully monitoring andhandling during the spinning.
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 11
RF and CMM Measurements
CMM setup and scans at 0, 45 and 90 degrees, respectively
Frequency and Q measurementsof half shells; Cu tape for betterRF contacts
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 12
CMM Profiles
3 CMM scans per half shell conducted at 0o, 45o, 90o, respectively
201 MHz Muon Cavity Shell #1 CMM Profiles
0
4
8
12
16
20
0 10 20 30 40 50 60
Radial Dimension (cm)
Axi
al D
imen
sio
n (
cm)
Measured frequency of shell-1: 196.97 MHz
(simulated frequency: 197.32 MHz)
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 13
Stiffener Rings
Two stiffener rings were fabricated at Mississippi University
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 14
E-Beam Welding Preparation For The Stiffener Rings
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 15
E-Beam Welding of the S. Ring
Skip e-beam welding first to hold the stiffener ring in place, then finish the complete welding
“Spider” holder Stiffener ring
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 16
After Stiffener Ring Welding
Mechanical cleaning of the cavity inner surface (right) after e-beam welding of the stiffener ring (above)
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 17
Machining at JLab
Machining setup Cutting opening for beam iris and nose piece
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 18
Recent progress for the welding
fmeasured = 200.88 MHz
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 19
Fixturing for the welding
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 20
Ready For Equator Welding
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 21
Extruding tests at JLabExtruding tests at JLab
Prototype of Curved Be windows
Collaboration with Oxford University
Ms. S. Yang will talk on the window designs and FEA modeling
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 23
A brief review: Be window R&D
• Ideal windows– Transparent to muon beams– Perfect electric boundary to RF field– No detuning to cavity frequency
• Engineering solutions– Pre-stressed flat Be windows– Pre-curved Be windows – Grids
A pre-curved Be window:0.25 mm thick and 21 cm in radius (by Oxford Univ.)
Window profile
evolutions
From flat to curved windows
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 24
Curved Be Window Failed in forming Be window at room temperature
At that time (last MICE meeting), we believed the curved Be windows can be formed at high temperature (not at LBNL). It can be formed and brazed at Brush-Wellman Company. Purchase order has been placed. We received two curved windows recently.
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 25
Curved Be windows by BWM
Two curved Be windows for 805 MHz cavity: 0.254 mm thick and 16-cm diameterPre-formed the Be foils first at high temperature, brazed copper frames afterwards.The windows will be Ti nitrided at LBNL for high power test at MTA, Fermilab.
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 26
201 MHz cavity status201 MHz cavity status
Four half shells have been formed by spinning Cu stiffener rings were e-beam welded to two half shells The shells are being mechanically cleaned at JLab Shells are ready for machining prior to e –beam welding of
equator joint Equator weld fixturing has been fabricated at LBNL Cavity nose piece rings (Univ. of Mississippi) have been
brazed at LBNL Conceptual design of RF loop coupler with SNS RF windows E-beam welding of equator joint, READY Extruding four ports, QUALIFIED Chemical cleaning and electro-polishing of the cavity Pre-curved Be windows, QUALIFIED The cavity should be ready for test in MTA at Fermilab this
fall
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 27
Summary
The 201 MHz cavity design and fabrication go smoothly Spun shells ready for machining after e-beam welding Nose pieces, stiffener rings and fixture were made Support structures for the equator welding
Engineering design (details) is still continuing Ports (succeeded in extruding tests and qualified the
techniques) Couplers (done with conceptual design) Tuners
Significant progress on curved window design and fabrication– Succeeded in making S.S. curved windows– Succeeded in making curved Be windows for 805 MHz cavity
by Brush-Wellman company
The cavity will be ready for test at MTA, Fermilab this fall !
MICE Collaboration Mgt in CERNMarch 28 – April 1, 2004
Status of 201 MHz Prototype Cavity and Curved Be windows Derun Li
Center for Beam Physics LBNL Page 28
Questions ?Thank You!
