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 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 Item300K-60K (W)60K-4.2K (W)* Current leads (total) (HTS leads) Radiation load Shields supports (total)0.55- Magnets supports (total) Instrumentation wires (total) total % contingency *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 and

PT415 Cryocooler APT415 Cryocooler B (remote motor) Tooling windows Shields supports tubes Plus wire feed-in port Operation vacuum is 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 Calculated ΔT = 11 K  Assumptions:  Radiation load:11W;  Conduction heat of 53.2W.  1 st 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 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 supports Horizontal 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 LocationTemperature Regular 2 nd stage 4.0 ~ 4.1 K Regular 1 st stage35 K Thermal shield32 ~ 34 K Remote 2 nd stage12.7 ~ 12.8 K Remote 1 st stage29.9 ~ 30 K 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