Meeting AgendaMeeting Agenda

TargetTarget

• Progress• Some Issues• SC

• Motion Mechanism • HX• Cell

ProgressProgress• “Pre-Preliminary” Design Document

– Nice work by Dave Meekins

• Fan (25 l/s) – Design sidetracked for HX work

• But new motor here, impellers, etc.

– ANSIS fluid flow software bought

• HX (2500+ W: 4K HX AND 15K HX)– Detailed design + drawings basically finished

• Review in progress- very positive feedback• Dave has done a great job on this- very impressive

• Motion Mechanism– Conceptual design report by Jim Dunne

• Scattering Chamber– Bates/Sample SC at JLab now. Needs to be stretched.

• Cell & manifold will be outsourced

Some IssuesSome Issues

• Tgt is a FY06 spending priority. But:

• Tgt grp getting busier– Pol tgt in Hall B (& Hall C)– GEp Hall C requires new SC & complete

redesign of loop

• As our schedule stretches, we lose priority

• Need collab. Input on dummy tgts

FY 2006 - Qweak Budget Estimates

Budget supposed to be $400k for Qweak plus another $140k carryover for the stand,plus overhead,not including any (Hall C) power supply and Compton chicane money.

Total JLab(DOE) budget is therefore $540 for capital (not including overhead) in FY2006

Actual % of cost Budget Budget Budget BudgetPlan A Cost + + conting. over- Unloaded Contin- Over-

WBSConting. Budget head Cost gency head TotalQTOR Stand 4 180 107% 15 140 28 50 218Target minus scattering chamber 2 91 67% 27 91 45 40 176Scattering Chamber 2 50 48% 15 70 35 31 136Quartz Bar Housings 1 10 100% 3 8 2 3 13Detector support & alignment structure 1 26 100% 8 20 6 7.8 33.8Primary collimator 6 50 83% 15 50 10 17.7 77.7Secondary collimators 6 80 83% 24 80 16 28.3 124.3Detector shielding 6 30 34% 9 70 17.5 25.8 113.3Beamline shielding 6 25 40% 7 50 12.5 18.4 80.91' beam pipe 6 0% - 21 5.3 7.7 34

subtotal 542 70% 121.9 600 177.3 229.7 1007overhead 121.9 229.7

Total 542.0Jlab(DOE) FY06 Budget 540 121.9

Amount overspent 2.0 0%

BudgetFY06 Plan

FY06 JLab(DOE) SpendingFY06 JLab(DOE) Spending

Scattering ChamberScattering Chamber

• Bates/Sample SC here now– Thanks to our collaborators at Bates– Msrs ~ 3’ x 3’ x 5’ tall– Will need to make it taller for our loop

• But 3’x3’ footprint OK

– Stndrd Hall C SC changes may help us to stretch (GEp needs a new one)

– New service connections, etc. for sure

Sample Tgt:Specs:• 25 l H2 inventory• Vvol=7.9 l/s @ 30 Hz• Expected ΔT=0.3K @ 1kW• 40 cm, 40 μA (~500 W)• Outer cell 7 cm φ,

0.38mm thick• Windsock tapers to 3 cm φ,

0.13 mm thick• Reynolds # ~ 107

• m = 550 g/s @ 30 Hz• Vs=5 m/s @ 30 Hz• 3mm φ raster• External pump

.

Δρ/ρ < 1000 ppm

In BeamlineIn BeamlineNew lifter section

Existing Sample SC

Motion MechanismMotion Mechanism

• Conceptual design report by Jim Dunne– sabbatical next year to build lifter!

• Recycles parts from standard pivot tgt– BDS5 motor, driver, control software

• Motion in x (~±3 cm) & y (~30 cm)

• Long thin SS 8” Φ pipe to isolate loop

• Flexlines

• 3-axis lifter, single motor ala Hall C

Top Top ViewView

3 Targets (& an out) Geometry3 Targets (& an out) Geometry

Al Dummy X0 ~ LH2 X0

LH2

Full Current CX0 ~ LH2 X0

Target OUT position

VPI Sim:

Weighted θ & Φ accepted at

FPD.

3.5 mil cell window.

10 mil vacuum window.

Some MM DetailsSome MM Details

Coolant Issues Coolant Issues &&

Heat Exchanger Heat ExchangerDesignDesign

Heat Exchanger SchemeHeat Exchanger Scheme

4K HX>2 kW

3 atm 1.2 atm4K 20K

3 loops in series,Each at inner, mid, & outer

Layers to equalize ΔP

½” fin tube14 fpi

3” Φ

Leak test:500 psi !

15K HX design similar to 4K HX

15K HX>1 kW

15 atm 1.2 atm14K 20K

Cell Design

• Thickness of cell & windsock a compromise between engineering & experimental needs.

• Present plan: thin walled cylindrical Al cell with exit window thin nipple.

• Entrance window Be, no He backing cell.

• Flow diverter/windsock a conical, axially symmetric longitudinal Al tube.

• Total thickness of these components must be modeled. Special fluid ANSIS just bought.

• All joints in the cell/cell block will be welded or mechanical (no soldering)

VPI Sim. of transverse cell thicknessVPI Sim. of transverse cell thickness

10 mils ~ OK (ΔR~2%)

Al cell

Be cell

Mechanism for loss of rate seems

to be Bremsstrahlung ΔE, leading to greater Δθ in

QTOR

Transverse cell thickness in mils

Extended machined cell

innie

outie

10 mil Al

nipplePerforated windsock

cell block

End

Cryo Systems Capacities and Loads in equivalent g/s Rao Nov-10-04

Assumptions:

1. No degradation in the CHL & ESR Cryo Capacities 2. No increase in cryomodule static (vacuum) and dynamic loads 3. No increase in Hall magnet and transfer line static (vacuum) loads

Loads Capacity Present Near term Option -1 Option -2 Option -3 Option - 4 Option - 5Cryo loads Expected FEL @ Present FEL_Off Hall-A_Off SBR_On 4_Kw_On

FEL @ Present

CEBAF Linac 5.5 GeV 188 188 188 188 190 188 188CEBAF Linac 5.8 GeV 196 196

FEL Linac 20 20 20 20 20 20 20 FEL FL03 full power 10 10 10 10 FEL new Injector 5 5 5 5

Halls Base loads on ESR Ref. 11 11 11 11 11 11 11 11Halls Base load on CHL 5 5 5 5 5 5 5 5 Hall-C Moller 2 2 2 2 2 2 2 Hall-A Septa 5

CTF load on CHL 5

Total Cryo loads 224 241 226 208 226 241 249

Cryo CapacitiesCHL Capacity 235 235 235 235 235 235 235 235ESR Capacity 11 11 11 11 11 11 11 11SBR (estimate) 20 204 KW_Capacity_if installed 40 40

Total Cryo Capacities 246 246 246 246 246 266 286

Shutoff Hall-A (Credit) 7Shutoff Hall-C magnets (Credit) 2 2 2 2 2Shutoff Hall-C Target (Credit) 2 2 2 2 2

Available for Targets 22 5 24 42 31 29 41

Cryo Agreement/SolutionsCryo Agreement/Solutions

The G0 Target

Beam PowerBeam Power

• Need additional power for:– PID control– Conductive losses

• QW goal: 2500 W

Pb(W) = Ib(μA) · (g/cm3) · t(cm) · dE/dx(MeV/g/cm2)

~ 2100 W

With: 180 μA, 0.072 g/cm3, 35 cm, 4.7 MeV/g/cm2

Pass Energy

Desired Beam Energy: 1.165 GeVInjector Energy: 0.0620 GeV (0.1125*linac energy)

LinacEnergy E/pass Pass 1 Pass 2 Pass 3 Pass 4 Pass 5

0.551 1.103 1.165 2.268 3.371 4.474 5.577 Optimum 0.0230.283 0.567 0.598 1.165 1.732 2.298 2.865 2.7350.191 0.381 0.403 0.784 1.165 1.546 1.927 3.6730.144 0.287 0.303 0.591 0.878 1.165 1.452 4.1480.115 0.230 0.243 0.474 0.704 0.935 1.165 4.435

0.593 1.187 1.253 2.440 3.627 4.813 6.000 (maximum)0.564 1.127 1.191 2.318 3.445 4.573 5.700 (maximum these days)

0.583 1.165 1.231 2.396 3.561 4.726 5.891

With 180 uA of beam current, this beam energy gives 210 kW of total beam power.

Under uniform pressure p, the following stresses exist

t

pr

tltrlp

t

rp

trpr

t

t

l

l

22

2

)2(2

longitudinal

tangential

AL7075-T6 Cell

in 009.0)41500(

)120)(3(

is failure) (vac pressure psia 120at

thicknesscell minimum thecelldiameter in 3 aFor

number this1/2 is stress allowable maximum The

83

is T6-7075 Al ofstrength tensileultimate The

t

ksiTult

Exotic materials

• Try Be or an AlBe alloy.– Ultimate strength is about ½ that of Al 7075– Radiation length is 4 times larger– There is some gain in doing this.

• Many issues with this choice– Safety– Machinability Something thin enough to be

useful may not be practicable.

Scaling a G0-like PumpScaling a G0-like Pump

Vane-axial (Archimedes screw) pumps:

QW/G0: Input: Output:Outer Diameter: pumpod 4.67 (in) Area: afan 52.62 (cm^2)Inner Diameter: pumpid 3.38 (in) A*pitch: apfan 234.43 (cm^3)Pitch: pitch 1.754 (in/rev) A*pitch*nu apnufan 28.13 (l/s)Frequency: nu_pump 120 (Hz) " * effi V_vol 18.57 (l/s), ie 18567 cm^3/sPump efficiency: effi_pump 66%

Density: rho 0.072 gm/cm^3 MassFlow mdot 1336.79 g/sdE/dx dedx 4.7 MeV/g/cm^2 At pump, v= vpump 5.35 m/sCp Cp 10.38 J/g-K Pump power= pumpower 19.10 Wdynamic viscosity mu_vis 1.30E-03 g/cm-s So torque needed is torque 35.11 oz-in

Flow area dim 1: flow1 2 Flow Area: aflow 7 cm^2Flow area dim 2: flow2 3.5 Stream velocity: vs 2652.37 cm/sTarget length Ltgt 35 cm transverse time t_trans 0.15 ms (time to cross beam spotPipe/cell diameter diam_cell 2 inches E dep in this time de_inc 0.009 J/cm assuming transverse flow)

dT local dT_local 0.077 KBeam current Ibeam 180 uA Beam power P_beam 2131.92 Wbeam size d_raster 0.4 cm (beam or raster size)Scattering angle theta 6 degrees has transverse dim y_scat 3.68 cm at end of cell.

Reynold's number Reynold 7.46E+05

Current Status

• Design of Hx’s complete– Drafts to be approved by Cryo– Assembly can begin in house at this point

• Cell design is underway plan to have this finished by June 1

• Loop layout complete by June 1• Pump prelim design complete by July 1

– Pump tests in Sept

• Safety (relief sizing gas handling …)

Squeezing it drySqueezing it dry

• Supplement with (more) 15K from ESR

• Run target at 21K or 22K instead of 19K

• Shave Preserve (350W 150W?)

• Schedule during Hall A reconfig. (gain 5 g/s)

• Run longer at lower beam current

• Run at higher P higher T greater cooling power

If we’re close, how to get the last little bit?

VPI Simulation:

X & Y at the exit window of the tgt

cell for events that hit the upper FPD.

No mult. scat. in tgt.

Up/θ

HorizontalΦ

QQweakweak Cooling Specs Cooling Specs

• 180 µA (parity quality) beam• 1.165 GeV in 1 pass (5.5 GeV 5 pass equiv.)

• 35 cm LH2 target• 19K or 20K operating (return) temp.• ~2.5 kW cooling power required

– ~2.1 kW beam power– ~0.4 kW overhead

• Exceeds standard capacity of ESR (1.2 kW)• Experiment installation late 2007, 1st run ~ 6 mo.

Qweak ContextQweak Context

3

Qweak/Cryo/Target Group MtgQweak/Cryo/Target Group Mtg

• All parties now agree on load required: – (25 g/s 4K supply, 19K return)

• All parties now agree on dual tgt design: – Up to 2500 W 4K HX – Up to 800 W 15K HX

• All parties now agree dual HX concept works– Assumes current loads– Load balancing. Flexibility.

Agreement on all fronts!

ConditionsConditions

– Tgt return temp > 19K– Additional FEL load beyond present 20 g/s

would create a conflict– Hall C HMS 80K– Hall C Moller on cold return– Hall A modest program (no high power tgt)– Special filling or extra/unusual demands

reduce load temporarily on Qweak target

Happex Lessons• June ’04: Ran successfully off main CHL coldbox

excess capacity. – Max flow received was 24 g/s– Max flow data acquired at was 20.4 g/s – Route: CHL-ESR-”15K supply”-20K return-ESR

• actual supply temp. was ~4K, returned “warm”

– Acc: 0.99 GeV/pass, 3.036 in Hall A. Hall B (4 GeV), Hall C off. Hall A spectrometers & septa on.

– 19K LH2 results: 62-75 W/(g/s) cooling power• only actually pulled 6-8 g/s due to septa limitations• We need ~2100 W cooling power 28 g/s

– 6.6K He target: estimated 23.7 W/(g/s)

Fact: Hall A ran 24 g/s off CHL excess 4K capacity in summer 04!

Happex He: 6/10-16Happex H2: 6/19-7/25Hall C: on after 6/19

23 g/s

Outstanding Cryo Issues• Can Moller operate at 5K?

– Using data for NiTi superconductors suggests yes

– A test of 5K 3Tesla Moller operation should be performed

• Moller would use ~3-4 g/s to increase total CHL draw to 19 g/s

• Hall A lead flow still 1-2 g/s, total would be ~21 g/s

• Scheme uses existing plumbing and refrigerators

• Operational procedures for Target cool down/warm up, ESR trip/recovery, CHL trip/recovery would have to be adjusted.

• Conditions would be similar to HAPEX 2004 running in Hall A

Dual Hx PossibilitiesDual Hx Possibilities

• With 4K refrigerant• Using a modest

flow of 15 g/s at the target

• 1560 W of cooling power

• With 15K refrigerant• Using modest flow

of 15 g/s at the target

• 525 W of cooling power

Total is ~2100 W of cooling power

Heat Exchangers

• To make use of all refrigeration options– Use 2 Hx– 5K refrigerant High Power Hx– 15K refrigerant Auxiliary Hx

• 4K Hx is large enough to provide > 3kW of power

• 15K Hx is large enough to provide > 700W of power

5 Scenarios1) CHL, QW 2 pass (>100% QW needs):

• No cryo-load problems, but E/pass unpopular

2) CHL, QW 1 pass (80% QW needs):• Schedule during moderate Hall A load• Same solution Hall A Happex II is using summer ‘03• Schedule while Hall A off (reconfig) 100% QW needs

3) Backup CHL (SBR) as is (60% QW):• Inefficient, insufficient

4) Upgraded SBR:• New xfer line, compressor, spare parts (~$1M)• Broader solution for JLab• 1.8 kW @ 4K (~75%), higher at 15K (being studied)

5) ESR Upgrade (>100% QW)• 4 kW goal, no load problems or QW limitations, broader

sol’n. for JLab. $3M + 3 years.1/03

Possible Sources of CoolingPossible Sources of Cooling

ESR 15K• supply: 15K

@ 12 atm• return: 20K @

3 atm• ΔH = 35 J/g• Need ~ 70 g/s

• mmax~ 25 g/s

ESR 4K• supply: 4K @

3 atm• return: 5.5K @

1.2 atm• ΔH = 26 J/g• Need ~100g/s

• mmax~ 50 g/s

CHL 4K• supply: 5K @

3 atm• return: 20K @

1.5 atm• ΔH = 104 J/g• Need ~ 24 g/s

• mmax~ 20 g/s

(@ 5.5 GeV)

ESR is 1200 W max,only half what we need

close to what we need-in fact Happex got 24 g/s

fragile!

CHL 4K Capacity• Minimum 190 g/s, Maximum 240 g/s

– Depends on E/pass (5)

• Flatout (~5.8 GeV): uses 215 g/s (for accelerator)– Need 5g/s for Hall A lead flow, + 5g/s reserve– Leaves only 15 g/s available for QW (60%)

• Normal (< 5.5 GeV): uses 210 g/s– Still need ~ 10 g/s for lead flow + reserve– Leaves 20 g/s available for QW (80%)– Happex II solution, summer 04– If scheduled during Hall A reconfig gain 5g/s QW (100%)

• Reduced (< 3 or 4 GeV): uses 190-200 g/s– At least 30 g/s available for QW (>100%)

1/03

Refrigeration

• There are 2 refrigerators possibly available for our use.– Standard ESR at 15K (~800W)– CHL extra capacity (~5-2500W)

• Availability of this capacity is in question• Current FEL plans present Qweak with difficulties

• We need upwards of 2500W for our target.

4K HX Parameters4K HX Parameters

Hydrogen ParametersPLH2 40 psi hydrogen operating pressureTLH2 20 K temperaturerhoLH2 0.072 g/cm^3 densitymdotLH2 1336.792 g/s mass flowCpLH2 8.82 J/g-K specific heatetaLH2 1.35E-04 g/cm-s viscositylambdaLH2 9.86E-04 W/cm-K thermal conductivityPrLH2 1.3 1.21 Prandtl number = eta*Cp/lambdaAflowLH2 26.5 cm^2GLH2 12.6 g/cm^2-s 10.99 mass flow rate per unit area=mdot/AflowDeLH2 0.46 cm effective diameter for HX=4*xsectional area of tube/(perimeter of surface to which heat is transferred)AhexLH2 31 cm^2/inch effective area for heat exchange (HX)

Helium ParametersPHe 36.75 psi hydrogen operating pressureTHe 4.5 K temperaturerhoHe 0.128 g/cm^3 density 0mdotHe 5 g/s mass flowCpHe 4.89 J/g-K specific heatetaHe 3.50E-05 g/cm-s viscositylambdaHe 2.00E-04 W/cm-K thermal conductivityPrHe 0.86 0.86 Prandtl number = eta*Cp/lambdaAflowHe 0.164 cm^2GHe 30.5 g/cm^2-s 5.34 mass flow rate per unit area=mdot/AflowDeHe 0.46 cm effective diameter for heat exchange=4*xsectional area of tube/(perimeter of surface to which heat is transferred)AhexHe 3.7 cm^2/inch effective area for heat exchange

Squeezing out the Cooling PowerSqueezing out the Cooling Power

• Run at higher P– 24 psia 40

psia• Run 2K

subcooled– instead of 3K

• Increase ballast volume to reduce pressure rise on boil

• Win 3K !

4K coolant win ~15%15K coolant win 75%

4K HX Design4K HX Design

Heat Exchanger Geometrytubediam 0.5 in fin tube diameterfinheight 0.25 in fin heightfinpitch 16 fins/innlayers 3 # of layers of fintune coilsturns 15 # of turns of fin tube per layercorediam 3.625 in diameter of the inner mandrel/plug/flow diverter around which the coils are woundtubethk 0.035 in tube wall thicknesseffahe 8.72 cm^2/in effective area for heat exchange per inch of fin tube for Heeffalh2 131.74 cm^2/in effective area for heat exchange per inch of fin tube for LH2aflowHe 0.94 He flow areaaflowLH2 121.61 LH2 flow areaL1 217.95 in total length of 1st layerL2 312.20 in total length of 2nd layer H2L3 406.44 in total length of 3rd layer out 20 20.21 inL 936.59 in total length of fin tube 4.5 20.14

He

out in

cell

pump/fan

4K HX Performance4K HX Performance

20 20.21 H2Delta T_LM 4.5 20.14 Heibeam 180 uA beam current dT= 15.5 0.07dedx 4.80 MeV/g/cm^2 dT_LM= 2.857 2.857draster 0.4 cm raster dimensionvflow 2652.365 cm/s flow speed from the pumpdT_flow 0.092 K expected temperature rise from this beam current & pump speedt_tgt 35 cm target thicknessPower_needed 2175.9 W power for this target length & beam currentmassflowHe 24 g/sMax_cooling 1835.749 W maximum cooling power for this mass flow and coolant dT HXPower_goal 2500 W Desired power goal for this HX H2tlh2i 20.2120 K LH2 Temp at HX inlet (from desired power & fan speed) out 20 24.1 intlh2o 20.00 K LH2 Temp at heat exchanger outlet 4.5 17thei 20.1420 K He Temp at heat exchanger inlet Hetheo 4.50 K He Temp at HX outlet (coolant supply temp) 24.1dto 15.5 K difference between the coolant and target fluid temperatures at the HX outlet out indti 0.0700 K difference between the coolant and target fldui temperatures at the HX inlet 20 24.1 H2dtlm 2.87 K needed to get power goal 4.5 17 He

2.857 determined from the tgt & coolant temps dT= 15.5 7.1-0.012 Use SOLVER from tools menu to get thei

Heat Exchanger Performance dT_LM= 10.759 10.759hHe 0.284 W/cm^2-K heat xfer rate per unit area across each boundary layer maxpower 9375.293 6.630hLH2 0.259 W/cm^2-K heat xfer rate per unit area across each boundary layerU 871.39 W/K assuming 100% HX efficiencyQdot 2500.00 W Heat transfer rate Power (W) 500Reqrd coolant 32.68 g/s need dTLM 0.574

cell

pump/fan

4K HX Performance4K HX Performance

20 20.17 H2Delta T_LM 4.5 20.15 Heibeam 180 uA beam current dT= 15.5 0.02dedx 4.80 MeV/g/cm^2 dT_LM= 2.327 2.327draster 0.4 cm raster dimensionvflow 2652.365 cm/s flow speed from the pumpdT_flow 0.092 K expected temperature rise from this beam current & pump speedt_tgt 35 cm target thicknessPower_needed 2175.9 W power for this target length & beam currentmassflowHe 24 g/sMax_cooling 1836.64 W maximum cooling power for this mass flow and coolant dT HXPower_goal 2000 W Desired power goal for this HX H2tlh2i 20.1696 K LH2 Temp at HX inlet (from desired power & fan speed) out 20 24.1 intlh2o 20.00 K LH2 Temp at heat exchanger outlet 4.5 17thei 20.1496 K He Temp at heat exchanger inlet Hetheo 4.50 K He Temp at HX outlet (coolant supply temp) 24.1dto 15.5 K difference between the coolant and target fluid temperatures at the HX outlet out indti 0.0200 K difference between the coolant and target fldui temperatures at the HX inlet 20 24.1 H2dtlm 2.30 K needed to get power goal 4.5 17 He

2.327 determined from the tgt & coolant temps dT= 15.5 7.10.032 Use SOLVER from tools menu to get thei

Heat Exchanger Performance dT_LM= 10.759 10.759hHe 0.284 W/cm^2-K heat xfer rate per unit area across each boundary layer maxpower 9375.293 6.630hLH2 0.259 W/cm^2-K heat xfer rate per unit area across each boundary layerU 871.39 W/K assuming 100% HX efficiencyQdot 2000.00 W Heat transfer rate Power (W) 500Reqrd coolant 26.13 g/s need dTLM 0.574

cell

pump/fan

Major Subsystems

• Loop Components– Heat exchangers– Recirculating pump– Cell

• Positioning system• Gas handling system

– Panel– Relief and storage

• Control system

Comparing the numbersComparing the numbers

• Old arithmetic (1/03):– CHLmax=240 g/s

– ACC needs 210 g/s

(@5.5 GeV)– less 5 g/s Hall A lead

flow– less 5 g/s reserve

– leaves 20 g/s for Qweak

• New math (11/04):– CHLmax=235 g/s

– ACC needs 188 g/s

(@5.5 GeV)– less 20 g/s FEL– less 5 g/s ESR

baseline support

– leaves 22 g/s for Qweak

2 ways ~consistent if the new CHLmax is lower to account for the Hall A lead flow.Note that neither way includes:

-5 g/s for Hall A septa (will this still be the case? I think that’s fixed now).-4 g/s for Hall C Moller (unless it’s run differently/separately)-CTF load (5-10 g/s?)

Fact: Hall A ran 24 g/s off CHL excess 4K capacity in summer 04!

Mass Flow Requirements at Mass Flow Requirements at Higher Return TemperaturesHigher Return Temperatures

• with 4K supply, 25 21 g/s significant given 20g/s limit

• with 15K supply, substantial savings:

85 54 g/s

Outstanding Issues

• Can Moller operate at 5K?– Using data for NiTi superconductors suggests yes– A test of 5K 3Tesla Moller operation should be

performed• Moller would use ~3-4 g/s to increase total CHL draw to

19 g/s• Hall A lead flow is still 1-2 g/s the total would be ~21 g/s• Scheme uses existing plumbing and refrigerators• Operational procedures for Target cool down/warm up,

ESR trip/recovery, CHL trip/recovery would have to be adjusted.

• Conditions would be similar to HAPEX 2004 running in Hall A

High Power Hx overview

end of questions

QW Refrigeration Solutions

• 4K/19K CHL Solution:– Supply 4 K, 3 atm– Return 19 K, 1.2 atm– ΔH ~ 103 J/g– m2500W ~ 24 g/s

• Can only get ~20 g/s max

(20 QW + 5 Hall A + 5 reserve for CHL)

• Some extra costs

– Existing xfer lines ~OK– ESR decoupled

• ~Solves QW needs, but:– Coupled to CHL ACC– 19K return is 300K at CHL– Not a general solution, but

• HAPPEX II will do this too

– Only 80% of our needs

– Tfreeze=13.8 K, small ΔP

– Scheduling issues • Similar to HAPPEX II (AC)

.

Existing Solution: Use the JLab CHL as is:

1/03

• Standard LHe tgt soln:– Use ESR (+CHL 5g/s)– Supply 4K, 3 atm – Return 5K, 1.2 atm– ΔH ~ 26 J/g– m2500W ~ 100 g/s– But mmax(ESR) ~ 45 g/s

• Includes 4K magnet flow

• Has been used for LH2 but:– Tfreeze=13.8 K, ΔP small– Low flow– Pmax (ESR) ~ 1200 W

Target Refrigeration at JLab• Standard LH2 tgt soln:

– Use ESR (+CHL 5g/s)– Supply 15K, 12 atm– Return 19K, 3 atm– ΔH ~ 31 J/g

– m2500W ~ 80 g/s

– But mmax(ESR) ~ 25 g/s• Total for both A&C

..

..

ESR for QW

1/03

QW Refrigeration Solutions

• Backup CHL 14K Soln.:– Supply 14 K, 15 atm– Return 19 K, 3 atm– ΔH ~ 38 J/g

– m2500W ~ 66 g/s

– Existing xfer lines NOT OK

• $1M for new 20K xfer line (ESRCHL), compressor upgrade, spare parts

– Plenty of capacity (~4kW)

• Also a 4K solution– less efficient, less power

• Solves QW needs, and:– Broader JLab solution

– Tfreeze, ΔP not issues @ 15K

– Efficient & safe use of our CHL backup plant

– Existing Hall C & supply lines (CHLESR) OK

.

Preferred solution: Upgrade the JLab backup CHL. ( SBR)

1/03

More Sub-cooling = Less Boiling

5K sub-cooled!

• 25 psia & 19K:

• ~ 2.5K sub-cooled

• 40 psia & 19K:

• ~ 5K sub-cooled!

• harder to boil

• Can’t lower T though

• need the cooling power, T

Coolant Loads

• New hits on reserve CHL capacity:– problem FEL cavity: 10 g/s more– (1/2) Hall A septum: +5 g/s more

– That’s 15 of the 20 g/s we were counting on for QW

• Ought to force lab to bite the bullet re SBR/ESR upgrades. HAPPEX driving timetable (for us):– presently only ~7 g/s available for them– New: SBR upgrade (~1M$) now high priority for lab

• cold return line, new compressor, sparing 4kW capacity

• Still have inefficient, $$ CHL SBR option:– 20-25 g/s 4K (tomorrow)

Scattering Chamber & LifterScattering Chamber & Lifter