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 1.5W@4.2K.

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