13 Dec. 2004 MAC Review – Future IR Heating Issues 1 Future IR Heating Issues 13 December 2004...

13 Dec. 2004 MAC Review – Future IR Heating Issues 1

Future IR Heating Issues

13 December 2004

Stan Ecklund


IR Heating Issues - Overview• Since Last Review (April)

– MD data with Vertex Bellows cooling off and – Data on bunch length dependence of HOM power.– New improved chiller system for cooling water.

• Status– HOM Heating

• Vertex Bellows 2002 Cooling is working well – Power now 500 W• Q1/Q2 Bellows

– Larger HOM absorbers in 2002.– Will need to improve HOM/Power capability - now 11 KW

– Synchrotron Radiation• LEB B1 Fan Hits LEB Leg of Q2 Crotch and Q4 chamber

– May be cause of magnet motion (~20 microns).– New Q4 chamber, bellows and Q5 chamber

• HEB – B1 fan aimed at High Power Dump must miss Q5R chamber flange. New Q5R chamber.


Near IR


IR Vacuum Chambers


Forward Vertex Bellows – Before Cooling

T_VTX2 Thermocouple( dT = 105 F = 58 C)

Beryllium Vertex Chamber B1 Chamber

Hottest Point according to model (300 C)


Forward VTX BLWS Cooling


Thermocouple LocationsT_V0B270 On Ta foil, z=blws-70mm -y x=0,z=113 mm

T_V1B270 Al Clam, end near IP, -y, theta=270 z=157

T_V2B270 Al clam, corner theta=270, z=17.5

T_VTX2 TC1: Forward alum clamshell (+y)

T_V3B000 Inboard end of blws theta=0





T_V3B_O Inboard H2O out, -x +y

T_V4B_O1 Collar H2O out -x

T_V4B_O2 Collar H2O out +x

T_V5B000 SS end of B1 Chamber theta =0

T_V5B180 SS end of B1 Chamber theta =180

T_V3B_AI Air in Bellows, top

T_V6B_AI Air btwn B1 chamber &

magnet,+y,z=295mm,slice3/slice4


VTX Bellows Cooling Installation


Vertex Bellows Cooling Added in 2002 is still working• Increased Currents: From 1500 on 1000 to 2450 on 1500

• Shorter Bunch Length

• dT=reduced by factor of 2.7

• Time constant 100 sec vs. 220 before

• OK with today’s increased currents and till 2006 plan.

• Next design needs cooled absorber


Vertex Bellows Absorber Design


Erratic Behavior Similar to Before


Cooling off T_VTX2

Forward Vertex bellows

• Step Change at 1400 ma – Step -0.004 out of 0.034

or 12%

– From bellows motion?

• Data in Blue• Fit in Red • Time constant 221 sec• Linear term 0.00985

– dT = 14 F at 1400 ma

• HOM term = 0.0341– dT = 44 F at 1400 ma


Cooling off Summary


Backward and Forward Vertex BLWS Temperatures


Angular Dependence Total T (F) at 1400 ma

60

70

80

90

100

110

120

130

-60 0 60 120 180 240 300

Angle (degrees)

V3B

V5B

V3A

V4A

V5A


Thermo Model

(May 2001)

for 100 Watts Power input

behind fingers.

Does not match data

in detail.


LER Bunch Length MD

• Vary Vrf = [2.9, 3.2, 3.8, 4.5, 4.8 MV], ILER =[500, 1000, 1400]

• Fit T(t) = T0 + L * ILER + LHOM * (ILER2 / Nb) *(Vrf /3.8 MV)

• Exponential time response of temperature • Good fit with above form with linear RF gap voltage driving HOM• For hottest TC T_VTX2

L = 0.0024 degF/ma

LHOM = 0.0123 degF/ma2

With out cooling LHOM = 0.0341 ( 2.77 times larger)

Projects to for LER HOM heating (add about 34% - 24% for HER):Jul 2004 LER 2500 ma, V=3.8 MV , HOM dT= 44 F

Jul 2005 LER 3300 ma, V=5.4 MV , HOM dT= 110 F




Vrf

I LER


Bellows Power July 2004

• Taken from max – min of Thermocouples HSTB data during a typical day

• TC on water out tubes

• Turbine flow meter measures water flow

• Mass flow meter measures air flow

• VTX 416 Watts

• Q1/Q2: 11 KW


Measured and Projected Power


LEB+HEB HOM Power ~ ib2 z-2


Be Vertex Pipe and Bellows


Synchrotron Radiation – Backward LER B1& Q1Fans

• LER Leg of Q2 Crotch chamber and Q4 chamber• dT=84 F / 2250 ma. • Suspect this is cause of observed magnet motion.• Working on ways to improve cooling on LER Q2 and Q4 chambers with additional cooling.

LEB side,+x,y=0, small Cu finger, z=-2.8 m LER Q4 vac, +x, z=-3.64 next to flange


LEB Fans


HEB Fans – new Q5 chamber


New Chiller Water System

• Improved Reliability– Heat exchange to IR2 Chiller with 4 units– Mixing valve and pump– New Allen-Bradley controllers

• Better Temperature Control– Heaters in hall for 10 individual water circuits can respond to

changes in beam heating quickly.– Sensors on IR vacuum chambers can control heaters.

• Full Flow strainer• Larger Capacity

– From 20 to 50 KW • Project completed this summer

– Some Programming work remains to be done.


Future IR Heating Issues - Summary• HOM Heating

– Planned increase in bunch current and decrease in bunch lengths drive up HOM heating dramatically.

– Increase in heating may be less if bunch length increases with bunch current.– Vertex Bellows:

• 2002 cooling works up to 1.8 A HER on 3.3 A LER• Add absorber to new design in next long downtime with ST removal.

– Q1/Q2 Bellows• Now taking out 11 KW• Expect power to increase to 22 KW• Working on design to handle higher power.

• Synchrotron Fan Heating– Backward LEB Q2 Leg and Q4 chamber needs solution for cooling/motion– Plan to take more Data to better characterize heating dependence on bunch

length, bunch current, number of bunches,…– Improve VTX Beryllium diagnostic.

• New Vacuum chambers– Spare forward Q2 chamber– Radial Ion pump– Q1/Q2 Bellows with improved power capacity– VTX Bellows with absorber– Q4, Q5 chambers …

13 Dec. 2004 MAC Review – Future IR Heating Issues 1 Future IR Heating Issues 13 December 2004...

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