LH2 Absorber Heat Load and Homeostasis. What has happened before… 1.Huge LH2 volumes, low heat...
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Transcript of LH2 Absorber Heat Load and Homeostasis. What has happened before… 1.Huge LH2 volumes, low heat...
What has happened before…
1. Huge LH2 volumes, low heat deposition: Bubble chambers
2. Small LH2 volumes, low heat deposition: FNAL E866
…here density fluctuations are an issue:3. Medium volumes, large heat deposition: Sample,
Slac E158Our challenge:
Large heat deposition and beam path is through entire volume of absorber!1. Liquid must move everywhere2. Need gauge of temperature and density uniformity
Sample and E158 Targets
E158 target ~60 liters Sample target ~25 liters
Beam size ~ 2mm: defines small turbulence scale, and is small part of total volume
Calibration was total measurement
Muon Ionization Coolingx x
z zP1
P2
absorber
accelerator accelerator
absorber
P1
With transverse focussing (solenoid) :
Rμ3
trans
xx
LmEβ
βf
L
ε
dz
dε
Multiple scattering
reductionemittance
max.forβLow
Heating term (Mult.Scatt.)Cooling term +
lengthradiation:LBe
c2pβ
dE
dzEβLv/cβ
R
2trans
RF cavity
RF cavity
Need to minimize heating!
Internal heat exchange: Convection is driven by heater and particle beam.Heat exchange via helium tubes nearabsorber wall.
Flow is intrinsically transverse.
Convection absorber design
Output from 2-dim Computational Fluid Dynamics (CFD) calcs. (K. Cassel, IIT). Lines indicate greatest flow near beam center.
Qualitatively demonstrated but parameters need to be measured. Prototyping of this design is being done by Shigeru Ishimoto et al at KEK.
Forced-Flow Absorber Design
Mucool ~ 100W (E. Black, IIT) Large and variablebeam width =>large scale turbulence
Establish transverseturbulent flow withnozzles
External Heat Exchange:
For ~ 8W/cm heat deposition, need to cycle 0.05 volumes/sec LH2 (e.g. 240W/30cm).
Nozzle design complicated - needs prototyping and testing.
So far… Three dimensional LH2 flow
simulations (W. Lau)
Testing 3-dimensional
simulations with water
flow test at NIU
1. Nozzle arrangement2. Heat application3. Cryo tests
Schlieren testing of convection flow
(water) test at ANL
Flow Tests Proposed
Three test modes (E.Black):
1. Absorber manifold , two plastic windows:Absorber filled with water at room temp. – the pattern of flow will be photographed by circulating water from inlet to outlet using a luminous die injected at inlet. Hard to get real window volume flow picture this way.
2. Absorber manifold, one plastic windows, one aluminum windowAbsorber subjected to a heat source. Infrared pictures taken (for forced-flow and convection absorber type). Distortion from heat distribution in window.
3. Absorber manifold , two thin Al windows, cryogenic:Absorber integrated into a cryo system, operating in test mode with extreme temperature and pressure variations considered for safety.
Yet to have a definitive determination of adequate probe placement.
Now, the questions…
1. What computations are helpful?
2. Are flow/convection predictions “linear”?
3. What tests will be useful, and how quantitative can they be?
4. What level of instrumentation will convince us of sufficient temperature uniformity?
5. How will convection and force-flow models be evaluated?