2K Cryogenic System Design for cERL at KEK Contents: • Background and Goal • 2 K Super-fluid Helium • Liquefier vs. Refrigerator • JT-Heat Exchager • High Performance Transfer Line • 2K Cryogenic System for cERL • Summary

KEK Kenji. Hosoyama

scale (cm)

0 5 10 15

Aluminum 80K Shield

Polyester Callor

G-10 Support Plate

G-10 Support Block

Stainless Steel ClipStainless Steel

Stainless Steel

Stainless Steel

Stainless Steel

φ 34

φ14

φ14

φ14

φ14

Screw

LN2 Flow

LN2 Flow

He Flow

He Flow

LN2 Return

LN2 Return

He Return

He Return

φ17.3

φ17.3

φ 28a

b

c

Background and Goal

• We had an old helium refrigerator (TCF200 500W at 4.4K or 250L/h ) got from NIMS (National Institute for Material Science).

• Design, construction and operation of 2K 40W cryogenic system for ILC prototype cryomodule was successfully completed.

For base line design of cERL 2K system, we adopted this. • High performance transfer line system and JT heat exchanger have

been developed by our group at KEK. • cERL 2K cryogenic system; Two 2K refrigerators for injector and main linac. Cooling power of each 2K ref. can increase up to 80W by addition of pump units. Total cooling power can upgrade by adding a new liquefier.

Helium Ref. System for cERL

Injector Linac Main Linac 2K Ref. #1 2K Ref. #2

Multi-transfer Line

Liq. Helium Dewar 3000L Helium Ref. Cold Box

TCF 200 LN2 Circulation System

Medium Pressure Helium Gas Storage

Cooling Tower Screw Type Helium Compressor

Helium Gas Pumping Units

Gas Bag

High Pressure Helium Gas Storage

Purifier

Liq. Nitrogen

Heat Load 10 mA x 5MV 2 K 8 W 4.5K 18 W 80 K 145 W

Heat Load 10 mA x 10 MV x 4 units 2 K 46 W 4.5K 30 W 80 K 191 W Heat Load 100 mA x 10 MV

2 K 31 W 4.5K 94 W 80 K 1000 W

Heat Load 10 mA x 15 MV x 4 units 2 K 102 W 4.5K 30 W 80 K 191 W

100 m3

50 m3

High Pressure Helium Compressor

2 K Super-fluid Helium

Use the latent heat of vaporization of helium Cold Pump Large System CEBAF, LHC, …. Warm Pump Small System KEK

How to make 2K Super-fluid Helium ?

Pres

sure

[bar

]

Saturated Vapor Pressure of Helium

2.0 K

4.4 K

Temperature [K]

0.03 bar

1.2 bar

Gas State

Liquid State

20 J / g

Enth

alpy

[ J /

g ]

Temperature [K] 2.0 K

latent heat of vaporization

Liq. He 1 l 1 / 8 kg 1 / 8 x 20 = 2.5 kJ Lig. He 1 l / hr -- 2.5 / 3.6 = 0.7 W

Cooling Power 1W -- Liq. He Consumption 1.4 l /hr

JT-Heat Exchanger

62 % 89 %

4.2 K

2.2 K

Super-fluid T~ 1.8 K

Normal Helium T~ 4.2 K

JT - Heat Exchanger

JT1

JT2

Pumping (Warm or Cold Pump)

Production ratio of 1.8K liquid helium can increase from 62% to 89% by lowering the temperature of expand liquid helium from 4.2K to 2.2K using the cold vaporized gas through JT-heat exchanger. Because saturated pressure of the 2K helium is very low, i.e. ~ 0.03bar, specially designed heat exchanger is required.

Small DP

2K Ref. & Cryo-module

2K Ref. Cold-box

Cryo-module

Cryo-module

2K Ref. Cold-box

2K J-T Valve

2K Heat Exchanger

2K Liq. He

Liq. Helium Level

2K Liq. He

Gas Helium Pumping

For Cool-down

Gas Helium

Gas Helium

Liq. Helium

Liq. Helium

Conceptual design of cERL 2K cryogenic system Gas Helium Pumping System

Gas Helium

Liq. He 3000 L

He Liq./ Ref. TCF 200 250 L/hr

2K Liq. He

4.4 K Liq. He

2K Cold-box #1

2K J-T Valve

2K Heat Exchanger

Multi-channel Transfer Line

Cryo-module

Gas He

Rotary Pump

Mechanical Booster Pump

2K Liq. Helium

4.4 K

2K cold boxes are installed near by cryo-modules 4K He liq. / ref. ; supply liq. He to the 2K cold boxes and cool the 4K heat loads. 2K cooling; is made by pumping at room temp. Note: 80K thermal shields are not shown. Cold connection

Detailed Design of 2K Cold Box To cool down the cryomodule from room temperature to 2K through 4.2K and to control the 2K liquid helium level constant during RF operation of SC cavity, many control valves are installed.

Heat Exchanger

Conceptual Design of JT Heat Exchanger for Version 2 (2K 30W)

Comment : Version 1 : Lamination Type (1.8 K Magnet Cooling System) Version 2 : Fined Tube Type 1/8 “ (2 K ILC Cavity Cooling System) Version 3 : Fined Tube Type 1/4” (2 K cERL Cooling System)

Cold Return Gas

Cold Return Gas

Liq. Helium In

Liq. Helium Out

SUS 60.5D

Copper 1/8” Pipe

Heat Exchanger fins are brazed to coiled tube

Heat Exchanger Fin made by punching press

Heat Exchanger

Cross-section

Lower pressure drop structure in return line Leak tight: the body made of steel parts and assembled by argon welding

System flow of cERL Cryogenic System

Multi-channel Transfer Line

Helium Ref. TFC 200 Cold Box

Cold Helium Gas Return

Liq. Helium

Liq. Helium Dewar 3000L

4.4 K Pot

4.4 K Pot

2 K Pot

2 K Pot

2K Ref. Cold Box

#1 2K Ref.

Cold Box #2

5K Shield

80K Shield

5K Shield

80K Shield

Pumping Pumping

LN2 LN2

Liquid Nitrogen Circulation System Cold Box

Liquid Nitrogen Screw Compressor 5 bar 30 Nm3/hr

Liq. N2 Helium Compressor

Pumping System

Layout of Cryogenic System

Helium Pumping System /

Gas Bag Helium Ref. Cold Box (TCF200)

Liquid Helium Dewar 3000L

Vertical Cryostats

Purifier

Multi-Transfer Line

Area for Cold Test 10 m x 5 m

2K Ref. #1

Area for Cryogenics 10 m x 20 m

Helium Ref. Cold Box for Upgrade

Liquid Helium Dewar

2K Ref. #2

10 m

10 m

High Performance Transfer Line 1

scale (cm)

0 5 10 15

Aluminum 80K Shield

Polyester Callor

G-10 Support Plate

G-10 Support Block

Stainless Steel ClipStainless Steel

Stainless Steel

Stainless Steel

Stainless Steel

φ 34

φ14

φ14

φ14

φ14

Screw

LN2 Flow

LN2 Flow

He Flow

He Flow

LN2 Return

LN2 Return

He Return

He Return

φ17.3

φ17.3

φ 28a

b

c

Small heat leak to cold helium piping ~ 0.05 W/m 80 K aluminum thermal shield, cooled by liq. nitrogen, intercept the heat leak form the room temperature parts.

Small cold mass --- thin stainless tube (0.5 t ) Stable operation during transient condition, i.e., recovery from the cold helium flow stop.

“Development of a High Performance Transfer Line System” Advances in Cryogenic Engineering Vol. 45, p1395, (2000)

Easy to assembling

Leak tight stainless welding

Good thermal contact Thermal shield is made by extrusion

Sub-transfer 80 K aluminum thermal shield Need liq. nitrogen circulation system

Main Transfer Line Sub Transfer Line

14

High Performance Transfer Line 2

Liq. He Flow Φ18, 0.5t SUS316L

Gas He Return Φ28, 0.5t SUS316L

Liq. N2 Φ14, 0.5t SUS316L

Valve Box 80K Al Thermal Shield

80K Al Shield Φ100, 2t

80K Al Thermal Shield Main Multi-Transfer Line

G10 Support Plate

Main Multi-Transfer Line

By the 80K aluminum thermal shield cooled by liquid nitrogen, the heat leak to helium line can reduce to ~ 0.05 W/m

2K Cryogenic System for cERL 1

2K Ref. 1

2K Ref. 2

Helium Ref. Cold Box

Liq. Helium Dewar 3000L Helium Gas Pumping Units

Multi-transfer Line

Gas Bag

Purifier

2K Cryogenic System for cERL 2

Summary • The cERL 2K cooling system consisted of helium refrigerator

TCF200, two 2K refrigerators with helium gas pumping system and multi-transfer line was proposed and designed in 2008.

• The main components of the system were constructed and installed in the experimental hall of the cERL by the end of FY 2009.

• Before start the new operation of helium refrigerator for cERL, we cleaned up oil in the flow line of the 1st heat exchanger using the solvent and replace the charcoal by new one.

• The commissioning of the helium refrigerator was started in September of 2010.

• The commissioning of the 2K refrigerator and helium transfer line without the cryomodule will be carried out and 2K cooling capacity will be checked very soon.