The 14th KEKB Accelerator Review Committee!

Cooling of Crab Cavities below 4K !

KEKB Crab Cavity Group!
(presented by NAKAI Hirotaka)!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK

2Overview!

• Past results of crab cavity performancemeasurements!
• Evacuation (cooling) system!
• 1st operation of evacuation system!
• Modification of evacuation system!
• 2nd operation of evacuation system!
• Operation plan!
14th KEKB Accelerator Review Committee/20090209!

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

3Cavity Performance Measured in R&D Phase

KEK10Q010910#1 without coaxial coupler (19980229)#1 with coaxial coupler (20010530)#1 without coupler at 2.8K (19980422)
Design Value

81000.5

11.5
V[MV]

22.5

3kick

14th KEKB Accelerator Review Committee/20090209!

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

Phase Diagram of Helium

KEK

Lambda Line
Saturated Vapor
Pressure Curve
Melting Curve

Solid
Pressure [MPa]42.5

He I (Liquid)
CriticalPointHe II(Liquid)

0.2Vapor

00123456

Temperature [K]14th KEKB Accelerator Review Committee/20090209!

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

5Flow Diagram of Evacuation System (1)!

KEK

To He Ref.
Comp. Intake

To He Ref.
Comp. Intake

RotaryPumps
Cooling
Water
Heater2 kW

Oil Traps

LHe Flow
LHe Return
LN2 Flow
LN2 Return
Connection Box

NIKKO Tunnel

D10/D11 Klystron Gallery

Crab Cavity
Cryostat

14th KEKB Accelerator Review Committee/20090209!

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEK

14th KEKB Accelerator Review Committee/20090209!

6Oil Sealed Rotary Pump

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEK

7Edwards E2M275 Specifications• Displacement：4867 L/min!
• Speed：4250 L/min!
• Number of stages：2!
• Ultimate vacuum (total pressure)!
– Without gas ballast：0.1 Pa!
– With gas ballast：0.5 Pa!
• Motor power：7.5 kW!
• Recommended oil：Ultragrade 70!
• Standard oil capacity：28 L!
• Weight：225 kg!
• Cooling water：120 L/h (20°C) → 2 L/min!

14th KEKB Accelerator Review Committee/20090209!

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

8Evacuation Unit!

KEKTo Helium
Compressors

Pump Chiller

From Cryostat

Oil Traps

Rotary Pumps

14th KEKB Accelerator Review Committee/20090209!

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEK

14th KEKB Accelerator Review Committee/20090209!

9Evacuation Unit (D11)!

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

10

1st Trial Operations (1)

KEK
10/2
1.5h

HER(D10)

LER(D11)

Technical Issues
and Operations

10/3
4h

Pump #2
1h

Pump #2

Pump #1

8.5h

1h

Pump #1

Pump #1

・Bad control of bypass valve→Adjustment of hysteresis set value・LER helium level low→About 3 % offset in data acquisition loop

14th KEKB Accelerator Review Committee/20090209!

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEK

11

Summary of 1st Trial Operations (1)1. Cooling of two crab cavities down to 3.7 K and2 hours continuous operation achieved.
2. High pump temperature and operation withevacuation line heaters off.
3. Cooling capacity of original chiller not enough andreplacement by larger chillers twice.!
4. No thermal oscillation observed.
5. No problem with heat load through evcuationlines.
6. Pump oil return from oil traps to pumps necessary.
14th KEKB Accelerator Review Committee/20090209!

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

12

1st Trial Operations (2)!

KEK
10/2
1.5h

HER(D10)

10/3
4h

Pump #2
1h

Pump #2

Pump #1

10/6

10/7

10/8

9h
▲
Chiller
Pump #2
15h
Upgrade1kW→2.7kW
Pump #1▲ Chiller Upgrade2.7kW→11.2kW

LER(D11)

Technical Issuesand Operations

8.5h

1h

Pump #1

Pump #1▲
Chiller
Upgrade1kW→2.7kW

23h
Pump #1
16h
Pump #2
Chiller Upgrade▲2.7kW→11.2kW・Bad control of bypass valve→Adjustment of hysteresis set value・LER helium level low→About 3 % offset in data acquisition loop
・Chiller water temperature rise→Introduction of 11.2 kW chillers
・Pump oil flow out, cooling of pump oil and discharged helium gas

14th KEKB Accelerator Review Committee/20090209!

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

13

1st Trial Operations (HER)!

KEKCRAB HER (D10) 2008/10/07-2008/10/08
1009080

Intake 1Body 1
Intake 2
Body 2Chiller #1

Outlet 1
Motor 1
Outlet 2
Motor 2Chiller #2

Temperature [°C]

7060
50
4030
20
109:
179:
30
9:
40
9:
50
10:0010:1
010:1
510:2
510:3
510:4
510:5
511:0
2
11:1
0
11:2
0
12:0
0
13:0
0
14:0
0
15:0
0
16:0
0
17:0
0
18:0
0
19:0
0
21:0
0
23:0
0
1:00
3:00
5:00
7:00
9:
00

014th KEKB Accelerator Review Committee/20090209!

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

14

1st Trial Operations (LER)!

KEK

CRAB LER (D11) 2008/10/07-2008/10/08
100
Intake 1
Body 1Intake 2
Body 2Chiller #1
Heater90

Temperature [°C], Heater Output [W]80Outlet 1
Motor 1
Outlet 2
Motor 2Chiller #2

70
60
50
40
30
20
10

14th KEKB Accelerator Review Committee/20090209!

00
8:00
6:00
4:00
2:00
0:

0:0
22

0:0
20

0:3
18

0:3
17

0:3
16

0:3
15

0:3
140:3
130:3
1255
11:

45
11:

35
11:

11:

25

0

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK15

Summary of 1st Trial Operations (2) !
•Results of trial continuous operation !
–Pressure: 72 kPa, Temperature: 3.7 K!
–Effective pressure control with CV80 valve!
–Required cooling capacity of chillers: 11.2 kW!
–Required water flow rate of chillers: 3 L/min!
–High temperature of discharged gas (about 85°C)!
–Much flow out of pump oil (0.2 L/h)!
•Further modifications!
–Circulation and cooling of pump oil!
–Cooling of discharged helium gas!
–Temperature monitoring at control room!
–Employment of safety valve in evacuation lines!

14th KEKB Accelerator Review Committee/20090209!

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEK

16

Estimated Duration of Modification!

1. Oil circulation

1 week!

2. Pump oil cooling

3 weeks!

3. Discharged gas cooling

3 weeks!

4. Cooling tower

1 month!

5. Plumbing of cooling water

1 week!

6. Electric power lines

1 month!

7. Trial operations &commissioning !

1 week!

14th KEKB Accelerator Review Committee/20090209!

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATIONKEK17Discussions on Technical Issues• Technical discussion with the pump company!
– Temperature rise is not abnormal!
– Oil refill during operation!

• Discussions on modifications of the system!
– Cooling of pump oil and discharged helium gas!
– Required cooling power of cooling tower!
– Electric power and water supplies!
– Locations of equipment!

14th KEKB Accelerator Review Committee/20090209!

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

18

Flow Diagram of Evacuation System (2)!

KEK

To He Ref.
Comp. Intake

Cooling Water

To He Ref.
Comp. Intake

DischargedGas Chiller

CoolingWaterHeater
2 kW
LHe Flow
LHe Return
LN2 Flow
LN2 Return
Connection BoxOilChiller

NIKKO Tunnel

Oil Traps
Oil Return

D10/D11 Klystron Gallery

Crab Cavity
Cryostat

14th KEKB Accelerator Review Committee/20090209!

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

19Pump Oil Chiller Unit!

KEK

Cooling Water Pump

From/To Cooling Tower
Oil Pumps

From/To Discharged
Gas Chiller (1.8 kW)
Oil Chillers(10 kW/unit)
14th KEKB Accelerator Review Committee/20090209!

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEK

20

Equipment Locations at D10

減圧ポンプ+オイル冷却システム

Evacuation & Chiller Units
Evacuation Line Heater

14th KEKB Accelerator Review Committee/20090209!

Cooling Tower 68 kW

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

21

Equipment Locations at D11!

KEK

Evacuation Line Heater

Cooling Tower 68 kW
Evacuation & Chiller Units

14th KEKB Accelerator Review Committee/20090209!

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEK

14th KEKB Accelerator Review Committee/20090209!

22Temperature Monitoring!

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

2nd Trial Operations

KEK
12/22

12/23

12/24

12/25

13:45

HER(D10)

Operation

8:30

Pump #1 ON

Pressure: 72 kPa, Temperature: 3.7 K

Pump #2 ON
Heat Load(W)Operation

Pump #1 OFF
Pump #2 OFF

50

30

14:30

LER
(D11)

23

9:00

Pump #1 ON

Pressure: 72 kPa, Temperature: 3.7 K

Pump #2 OFF

Pump #2 ON
Heat Load(W)Technical Issues
and Operations

5030

Pump #1 OFF

60 70 8090100▲：LER oil pump #1 over current→Reset thermal protection

14th KEKB Accelerator Review Committee/20090209!

▲：Refill of pump oil (5 L)▲：Low intake gas temp.→Evac. line heater ON

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

24

2nd Trial Operations (LER)!

KEK

CRAB LER (D11) 2008/12/23-2008/12/25
10090

120
CV1P008
Intake Gas
Outlet Gas
Motor 2

CV80
P80
Pump 1 Intake
Motor 1Heater

10080
7060
50
4060

4020

Temperature [°C], Heater [W]

Pressure [kPa], Valve Openings [%]803002010-40

Date
11:0014:0017:0020:0023:002:00
5:00
8:00
10:2011:0011:4512:3013:2013:5014:3015:2017:0020:0023:002:00
5:00

0-20

14th KEKB Accelerator Review Committee/20090209!

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEK

25

Pressure Control under Heat Load

Set Helium Pressure
ＳＶ＝７２ kPa

Helium Vessel Pressure

Heat Load from Heater

Pump Intake Pressure

14th KEKB Accelerator Review Committee/20090209!

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

KEK

26

Summary of 2nd Trial Operations!

•HER (D10): continuous operation for 67 hours under !
50 W heat load.!
•LER (D11): continuous operations for 43 hours under !
50 W heat load and for 17 hours under 100 W.!
•Helium pressure can be stably controlled at 72 kPa.!
•Heat load to refrigeration system is not so large, since !
the opening of LHe supply valve is not large even under !
100 W heat load to LER crab cavity.!
•Though oil exhaust can not be suppressed, operation !
can be continued with refill of oil every 2 hours.!
•Electric currents of equipment are larger than those !
specified.!
14th KEKB Accelerator Review Committee/20090209!

NAKAI Hirotaka!

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION

27

Operation Plan

KEK• Trial operations with rf power to crab
cavities are scheduled for late March or forearly April.

14th KEKB Accelerator Review Committee/20090209!

NAKAI Hirotaka!