gas system status phase ii helium4 gas system status >status update >result of tao tests...

GAS SYSTEM STATUSPhase

II

HELIUM4 GAS SYSTEM STATUS

>Status update>Result of TAO Tests>Thermodynamic behavior of the gas>Computational fluid dynamics simulations

29th CAST Collaboration Meeting – Patras (22-23 May 2006)

Nuno Alexandre ELIAS (PH-DI)

29th CAST COLLABORATION MEETING -PATRAS

Nuno Alexandre ELIAS [PH - DI] 2


II 4He Gas system status update

• Intervention in Mars (Opened MFB below to Cryostat)

- Installation of new pressure probe on the cold bore PTAO

- Installation of new Temperature sensors inside the cryostat

- Closure of Cryostat

• Search for TAO’s with new pressure sensor

- Vacuum measurements (optimize parameters and get noise level)

- Pressure fillings (ø, 2, 4, 6,8,10 mbar fillings)

• Data taking preparations

-Gas filling of the cold bore to last pressure setting before intervention

-Quench at 12900A, Transient on PTAO

• Data taking Runs

-15 new gas settings [total 43 → P= 3.58mbar (@1.8K)]

- Fluid mechanics inside the cold bore

• Computational Simulations of Gas behavior

• PATRAS (experiment coasts)




II 4He GAS SYSTEM




II

Pressure_A 10 mbar 1 2 4 6 10

T_cold 1.8 KT_warm 120 KL_cold 5000 mmL_warm 150 mmpipe diameter 43 mm

sS_cold 77.8 m/s 78.8 78.7 78.5 78.2 77.8sS_warm 644.6 m/s 644.6 644.6 644.6 644.6 644.6visc_cold 4.6E-07 Pa.s 4.6E-07 4.6E-07 4.6E-07 4.6E-07 4.6E-07visc_warm 1.1E-05 Pa.s 1.1E-05 1.1E-05 1.1E-05 1.1E-05 1.1E-05density_cold 0.273 kg/m3 0.027 0.054 0.108 0.163 0.273density_warm 0.004 kg/m3 0.000 0.001 0.002 0.002 0.004

Alfa 66.7 66.7 66.7 66.7 66.7 66.7csi 0.03 0.03 0.03 0.03 0.03 0.03Visc_cold 1.7E-06 m/s2 1.7E-05 8.5E-06 4.2E-06 2.8E-06 1.7E-06Visc_warm 2.7E-03 m/s2 2.7E-02 1.3E-02 6.7E-03 4.5E-03 2.7E-03

Visc_c/ac 2.2E-08 m 2.2E-07 1.1E-07 5.4E-08 3.6E-08 2.2E-08Visc_h/ah 4.2E-06 m 4.2E-05 2.1E-05 1.0E-05 6.9E-06 4.2E-06

Yc.Lc^-0.5 65.4 20.7 29.2 41.3 50.6 65.4Yh.Lh^-0.5 1.1 0.3 0.5 0.7 0.8 1.1

lamdac1 1.571 1.571 1.571 1.571 1.571 1.571lamdac2 16.818 16.818 16.818 16.818 16.818 16.818Yc1 81.9 81.9 25.9 36.6 51.8 63.5 81.9Yc2 268.1 268.1 84.8 119.9 169.5 207.7 268.1

66.7 66.7 66.7 66.7 66.7 66.7omega1 24 rad/s 6.5E+01 2.1E+01 2.9E+01 4.1E+01 5.1E+01 6.5E+01 deltaomega2 262 rad/s

freq1 3.89 rad/sfreq2 41.63 rad/s

1.0

10.0

100.0

1000.0

1 10 100 1000 10000

Yc

a

THERMOACOUSTIC OSCILLATIONS (past)

• Thermoacoustic oscillations were observed with 4He gas filling for p > 2mbar with f=3.7Hz and ~6% amplitude (p/p); Isentropic model gives 3.5% density fluctuation ().

• Phenomenon was studied and solutions designed; Damping plugs installed on the linking pipes

Pressure_A 10 mbar 1 2 4 6 10

T_cold 1.8 KT_warm 300 KL_cold 5000 mmL_warm 1000 mmpipe diameter 43 mm

sS_cold 77.8 m/s 78.8 78.7 78.5 78.2 77.8sS_warm 1019.1 m/s 1019.1 1019.1 1019.1 1019.1 1019.1visc_cold 4.6E-07 Pa.s 4.6E-07 4.6E-07 4.6E-07 4.6E-07 4.6E-07visc_warm 2.0E-05 Pa.s 2.0E-05 2.0E-05 2.0E-05 2.0E-05 2.0E-05density_cold 0.273 kg/m3 0.027 0.054 0.108 0.163 0.273density_warm 0.002 kg/m3 0.000 0.000 0.001 0.001 0.002

Alfa 166.7 166.7 166.7 166.7 166.7 166.7csi 0.2 0.2 0.2 0.2 0.2 0.2Visc_cold 1.7E-06 m/s2 1.7E-05 8.5E-06 4.2E-06 2.8E-06 1.7E-06Visc_warm 1.2E-02 m/s2 1.2E-01 6.2E-02 3.1E-02 2.1E-02 1.2E-02

Visc_c/ac 2.2E-08 m 2.2E-07 1.1E-07 5.4E-08 3.6E-08 2.2E-08Visc_h/ah 1.2E-05 m 1.2E-04 6.1E-05 3.0E-05 2.0E-05 1.2E-05

Yc.Lc^-0.5 65.4 20.7 29.2 41.3 50.6 65.4Yh.Lh^-0.5 0.2 0.1 0.1 0.1 0.1 0.2

lamdac1 1.571 1.571 1.571 1.571 1.571 1.571lamdac2 1.314 1.314 1.314 1.314 1.314 1.314Yc1 81.9 81.9 25.9 36.6 51.8 63.5 81.9Yc2 74.9 74.9 23.7 33.5 47.4 58.0 74.9

166.7 166.7 166.7 166.7 166.7 166.7omega1 24 rad/s 6.5E+01 2.1E+01 2.9E+01 4.1E+01 5.1E+01 6.5E+01 deltaomega2 20 rad/s

freq1 3.89 rad/sfreq2 3.25 rad/s

1.0

10.0

100.0

1000.0

1 10 100 1000 10000

Yc

a




IISearch for TAO’s with new pressure

sensor• New pressure sensor was installed inside the cryostat reading directly

the pressure of the cold bore

- Frequency spectrum of the pressure over all the measure pressure range shows NO modal oscillation with dominant frequency ~3.7 Hz above the noise level ~0.1% of the pressure setting and no relevant signal, compared with the vacuum case, was registered, other spikes attributed to electronic noise.




II QUENCH

Update to the quench transient curve

• New pressure sensor allowed to give better resolution of the curve for t<t0+100 milliseconds

• Its possible to compare the pressure increase downstream and upstream of the TAO damper

• New pressure sensor reacts faster than 100ms




II Model• Gas sent to the cold bore

T(K)

P(mbar) 0.02

T(K)

P(atm)20.34(eV)mγ

i

i

CRYO

CBB

RT

V

RT

VPn 100

j

j

bath

meteringB

RT

V

RT

VdPdn _1000 j –gas panel volumes

i

iCB

RT

V

R

VPn

8.1#

• Gas in cold boreCalculation is done taking stable conditions of the gas pressure in the metering volume

Sum of all fillings

Looking at the gas inside

• Can we assume the gas is at the same temperature as the cold bore?

• Is Tcryo a good indication of the temperature of the gas through all the cold bore?

• How does convection from hot regions affects the homogeneity of the gas inside the cold bore??

• How does the gas pressure affects these convectional effects??

• And the inclination of the magnet??

• Can this affect the coherence??

• Measurement techniques for gas density?? (laser interferometer?)




II CFD simulations

• Solid model of SS tube, outside magnet

• Temperature distribution along the pipe ( region with high temperature gradients)

• Does not take in consideration convective heat transfer due to gas

• Over 66,000 elements

• But this does not answer the question of what happens to the gas density




II CFD simulations (preliminary)

• 3D Computational fluid dynamics (CFD) model of gas inside the cold bore

• Covering all the magnet length (712,000 elements), long processing time

• Temperature on surface is an imposed boundary, coming from the solid model (future will include both fluid and solid model), windows are adiabatic.






MAGNET HORIZONTAL, 3mbar






• From window to window • Only magnetic length (9.26m)







MAGNET TILTED (+8º,mfb_up), 3mbar






• Only magnetic length (9.26m)


• From window to window





• CONCLUSIONS:

- Simulations to continue with more accurate model, finer mesh, both solid and fluid.

- Simulations to be extended to other pressures, angles, and different X-ray window temperatures (heating); decision to be taken on running conditions;

- Search for density measurement techniques (to scan the cold bore length)

- Results to be studied, to see possible effects on small reduction of coherent length and its implications.

- Heating effects of the gas on the magnet extremities, might result on a broadening of the density steps when compared with the specified, study!

- TAO’s should be avoided in future system because this would increase the heat transport to the cold bore.


II

3He GAS SYSTEM

>Functions>Requirements>Schematic>Open questions>Ongoing work>Updated Cost Estimate

29th CAST Collaboration Meeting - PATRAS

Nuno Alexandre ELIAS (PH-DI)/Tapio Niinikoski (AT-ECR)




II

Purge of oil in the hermetic 3He pump

Evacuation of all volumes at room temperature

Leak testing of all volumes at room temperature

Transfer of 3He from pressurized transport cylinder into the storage vessel of the gas system

Metered transfer of 3He into the magnet bores (by pressure stepping and continuous ramping)

Recovery of 3He in the event of a magnet quench

Normal recovery of 3He

Regeneration of charcoal traps

Transfer of 3He back into the pressurized transport cylinder.

3He GAS SYSTEM

• FUNCTIONS




II

Safety against loss of 3He

Precise metering of the amount of 3He in the magnet bores (Double filling per run and possibility to make pressure ramping)

Absence of thermoacoustic oscillations

Protection of the thin X-ray windows in the event of a quench.

Remote data logging of the state of the gas system, without feedback

No safety release of 3He elsewhere except to the safe storage vessel.

3He GAS SYSTEM

• REQUIREMENTS




II 3He GAS SYSTEM

Storage

Purging

Metering and Dosing/Ramping

Axion conversion region (cold bore)

Expansion volume

Recovery and circulation




II 3He GAS SYSTEM• OPEN QUESTIONS:• METERING AND DOSING:

Option A > 2 metering volumes, filling is done before and in the middle of the run.Precise, not cheap, low flexibility. All detectors ‘see’ the same setting.

Option B > 1metering volume for 2# settings ramping during tracking, Requires mass flow meter + controller for constant ramp rate, more flexible,Absolute precision lower than A, possible TAO’s

Option C > Continuous ramping covering more than 2# settings,Requires mass flow meter + controller for constant ramp rate, more flexible, Absolute precision lower than B, possible TAO’s

Option D > Continuous ramp down during tracking.Less disruption of the magnet than A, B and C, low precision,Requires mass flow meter + controller for constant ramp rate, more flexible (ramp rate can be changed), possible TAO’s

• RUN CONDITIONS Warm windows > Low cryopumping of desorbed gases into the window foil, good for

window transparency. (effect on X-rays ??)

Cold windows > Low heat transfer into the cold bore, good for gas stable density and magnet.

• X-ray Windows > PMAX. - Sudden Increase of pressure at cold, more testing




II 3He GAS SYSTEM

• Technical Design Report is ongoing should be finalized soon. (some decisions to be done)

• Description of Functions, operations and safety matters

• Main equipment specifications and dimensions

• Main work packages identified:•WP1-Platform for 3He pump + accessories, •WP2-Design of the integration of new cryogenic and check valves inside the cryostat.•WP3-Modifications of gas lines inside the cryostat•WP4-Modification of cryostat to pass cryogenic valve head•WP5-Installation of new cryogenic and check valves•WP6-Construction of Storage volume•WP7-Construction of Expansion volume•WP8-Construction of metering volumes•WP9-Construction of command panel to operate 3He pump and electro-pneumatic valves.•WP10-Construction of gas panel •WP11-Installation of new cryogenic pressure transducer

• near FUTURE: Start drawings of integration, and invitations to bid of main equipment, discussions with suppliers.




II Updated Cost Estimation

gas system status phase ii helium4 gas system status >status update >result of tao tests...

Documents

gas system slide

t gas system status

gas system functions

gas system metered transfer

preparations gas filling

new gas settings total

new pressure probe

measure pressure range