LBNL Test Cryostat Preliminary Design Review Tuning – Field Correction Soren Prestemon, Diego...
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Transcript of LBNL Test Cryostat Preliminary Design Review Tuning – Field Correction Soren Prestemon, Diego...
LBNL Test Cryostat Preliminary Design Review
Tuning – Field Correction Soren Prestemon, Diego Arbelaez,
Heng Pan, Scott Myers, Taekyung Ki
Outline• Existing cryostat review – Structure and capacities – Features of each main part– Recent cooling down test results
• The extended system– Extension details This is new, to be “reviewed”
The Existing Tuning Cryostat Structures • Vacuum Chamber
• Thermal Shields Assembly Tower shields
Main horizontal shields and flexible connections
• Suspension System Shields supports
Cold mass supports
• Binary Current Leads (Copper + HTS) Three rated current leads which carry 30A, 100A, and 500A
• Instrumentation
Cold mass support (vertical)
Cold mass support (horizontal)
Thermal shields supports
Instrumentation port
Instrumentation port
PT415 Cryocooler
Plus wire feed-in
The Existing Tuning Cryostat Structures overview
The Existing Tuning Cryostat Structures overview
Existing Magnet assembly
Tower shielding Cold box support Assembly (vertical)
Main shielding
• The existing cryostat is a conduction-cooled system with two cryocoolers (cryogen-free system).
• The cold mass could work at 4.5 K~40K with adjustable heaters.
• Thermal shields will work at around 50~60K.
• The existing cryostat has a designed heat load of < 2W at 4.5K, additional heat will apply to tune the operation temperature from 20K~40K.
The Existing Tuning Cryostat Features
The Existing Tuning Cryostat Overall heat load
Item 300K-60K (W) 60K-4.2K (W)*
Current leads (total) 52 1.08 (HTS leads)
Radiation load 11 0.06
Shields supports (total) 0.55 -
Magnets supports (total) 0.72 0.3
Instrumentation wires (total) 0.56 0.05
total 68.83 1.49
30% contingency 84.27 1.94
• *this column just shows the designed heat load for the existing cryostat, does not apply for the 20K~40K application.
• The current leads include one pair of 500A, one pair of 100A and two pairs of 30A.
• The cooling capacity of PT415 is 40W@45K and [email protected].
PT415 Cryocooler A PT415 Cryocooler B (remote motor)
Tooling windows
Shields supports tubes
Plus wire feed-in port
Operation vacuum is 10-7-10-6 torr
The Existing Tuning Cryostat Vacuum Chamber
The Existing Tuning Cryostat Thermal Shields Assembly
• Consists of tower shields, a main shield, thermal interception accessories, all of which are made of OFHC copper.
• Designed working temperature is 50~60K.• Flexible connections are adopted to connect the tower
shields and the main shield.• 45 layers of MLI superinsulation are applied on the outer
surfaces; one layer of Mylar is attached to the inner surfaces to reduce the emissivity.
The Existing Tuning Cryostat Thermal Shields Assembly
thermal interceptions
Copper lead
Tower shields
Main shield
45 layers of MLI blankets
The Existing Tuning Cryostat Thermal shields thermal analysis
CalculatedΔT = 11 K
Assumptions: Radiation load:11W; Conduction heat of 53.2W. 1st stage cold head is 55K
The test result (without the load of current leads ) is ΔT=3K
Horizontal supports
Bracket connected to “cold box” (old design)
G10 rod
Steel stud for G10 rod (G10 rod is inserted to the stud and glued by epoxy)
Release hole for epoxy
Release hole for epoxy
Warm end
Cold end
Formed bellows
Stainless steel tube
G10 rod
Cold mass cooling box
316 steel connection
G10 bracket
Vertical supports
Existing Cold Mass Assembly
The Existing Tuning Cryostat Cold mass suspension system• Consists of vertical and horizontal supports:
– Vertical support s are to load the entire cold mass;– Horizontal supports are to do the cold mass alignment.
• The vertical supports are designed to be able to load 300 lbs . • Both types of the supports have very low heat leaks.
The Existing Tuning Cryostat Cold mass suspension system
• Assume the cold end is 4.5K. • The heat leak through each vertical
support is 0.1W, the heat through the horizontal support is 0.05W.
Vertical supportsHorizontal supports
The Existing Tuning Cryostat Binary current leads
• There are three rated current leads: 500A,
100A and 30A.
• All of the current leads consist of
traditional copper leads (RRR=30 ) and HTS
leads.
• The size of copper leads have been
optimized for the minimum heat leak(for
500A lead, the minimum heat leak at full
current is 21W, 15.7W with zero current).
HTS leads
Thermal interception
Copper lead
The Existing Tuning Cryostat Instrumentation
Main GUI
Compressor GUI
• Monitor temperatures, vacuum, voltages, and status of compressors
• Extendable GPIB Bus for all of the measurements.
Labview based program has been developed for monitoring and recording data.
The Existing Tuning Cryostat Cooling down test
Location TemperatureRegular 2nd stage 4.0 ~ 4.1 K
Regular 1st stage 35 K
Thermal shield 32 ~ 34 K
Remote 2nd stage 12.7 ~ 12.8 K
Remote 1st stage 29.9 ~ 30 K
0 1 2 3 4 5 6 70
50
100
150
200
250
300
Tem
per
ature
(K
)
Operation hours
Regular 2nd-stage cold-end
Remote 2nd-stage cold-end
Regular 1st-stage cold-end
Remote 1st-stage cold-end
Tower (Remote)
Main Shield (hole cover-left)
Main Shield (hole cover-rigth)
Main Shield (middle_bottom)
Main Shield (end-left)
Main Shield (end-right)
Remote cooler being repaired by Cryomech.
Heat load : ~ 1.1 W
The Proposed Extended Cryostat Shielding extending
• The main shield can be extended with two extension spools at both ends.
• The extensions will NOT affect the thermal performance.
The New Extension spool
The original end flanges will remain
The Proposed Extended Cryostat Shielding extending
Extension shielding
Bolt connections
The overall length of new shields is about 77.1 in
The Proposed Extended Cryostat Vacuum chamber extending
The original vacuum chamber
The original end flanges will remain
Extension spool
Application of Cryostat to Central Field Corrector Development and Testing
• Small scale testing of undulator tuning system will begin in the cryostat in its current configuration– 100 A current leads– Temperature operation from 4.5 K to ~ 40 K– Instrumentation ports for heater switches and temperature sensors– Field measurements with pulsed wire method (local measurements
at fixed point with hall probe)
• Extended cryostat will be used to qualify the full length correctors for use in the ANL cryostat– Will accommodate lengths exceeding the ANL cryostat vacuum
chamber – Support system can accommodate the vacuum chamber length and
has ample load capacity for the chamber and corrector weight