Cooling of electrically insulated high voltage electrodes down to 30 mK – Dynamic measurements

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Cooling of electrically insulated high voltage electrodes down to 30 mK – Dynamic measurements. Eisel T., Bremer J., Burghart G., Feigl S., Haug F., Koettig T. CERN, 1211 Geneva 23, Switzerland thomas.eisel@cern.ch. Content. Electrodes integrated in AEgIS - PowerPoint PPT Presentation

Text of Cooling of electrically insulated high voltage electrodes down to 30 mK – Dynamic measurements

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Cooling of electrically insulated high voltage electrodes down to 30 mK Dynamic measurements

Eisel T., Bremer J., Burghart G., Feigl S., Haug F., Koettig T. CERN, 1211 Geneva 23, Switzerlandthomas.eisel@cern.ch

Studies of the Cryogenic Part with Load Lock SystemT. Eisel,CERN TE-CRG-CIAEgISNovember 11th, 2010 Page #Cryolab1Electrodes integrated in AEgISCooling source: Dilution Refrigerator (DR)Cooling design: SandwichTheory of dynamic measurementsSimulationResults of dynamic measurementsDiscussion/ conclusionContentCooling of electrically insulated high voltage electrodes down to 30 mK Dynamic measurementsStudies of the Cryogenic Part with Load Lock SystemT. Eisel,CERN TE-CRG-CIAEgISNovember 11th, 2010 Page #CryolabAEgIS1 experiment at CERNScientific goal: influence of g upon antimatterPenning trap at 100 mK deceleration of particlesAEgISCooling of electrically insulated high voltage electrodes down to 30 mK Dynamic measurements

DRMC1 http://aegis.web.cern.ch/aegis/home.html

Studies of the Cryogenic Part with Load Lock SystemT. Eisel,CERN TE-CRG-CIAEgISNovember 11th, 2010 Page #Cryolab

Standard cooling source: DR1(0.002 to ~ 0.5) KContinuous operationDilution of 3He in 4He0.0001W @ 0.05 KDilution RefrigeratorCooling of electrically insulated high voltage electrodes down to 30 mK Dynamic measurements1 http://cdms.berkeley.edu

Studies of the Cryogenic Part with Load Lock SystemT. Eisel,CERN TE-CRG-CIAEgISNovember 11th, 2010 Page #Cryolab3He 2 protons only one neutron4SandwichCooling of electrically insulated high voltage electrodes down to 30 mK Dynamic measurements

1 G. Frossati. Experimental Techniques: Methods for Cooling Below 300 mK. Journal of Low Temperature Physics, Vol. 87, Nos. 3/4, 1992Studies of the Cryogenic Part with Load Lock SystemT. Eisel,CERN TE-CRG-CIAEgISNovember 11th, 2010 Page #CryolabAntimatter creation/ annihilation (Illuminati) is periodically (200 s)Dynamic measurementsInformation on how fast inserted heat can be transferredKey property which determines the propagation-speed of a heat wave in an homogeneous material:

materials thermal diffusivity a (m2/s)

l . . . thermal conductivity . . . densitycp . . . specific heat capacity

Theory of dyn. meas.Cooling of electrically insulated high voltage electrodes down to 30 mK Dynamic measurements

Sandwichs thermaldiffusivity a*Studies of the Cryogenic Part with Load Lock SystemT. Eisel,CERN TE-CRG-CIAEgISNovember 11th, 2010 Page #CryolabTheory of dyn. meas.Cooling of electrically insulated high voltage electrodes down to 30 mK Dynamic measurementsSemi-infinite rod (one dimensional)One end imposed temp. function TH=f(t) (sin, pulse)TC=f(t) at certain distance Alteration of the original function (phase shift, attenuation)

materials thermal diffusivity acan be analytically solved

Studies of the Cryogenic Part with Load Lock SystemT. Eisel,CERN TE-CRG-CIAEgISNovember 11th, 2010 Page #Cryolab

SimulationCooling of electrically insulated high voltage electrodes down to 30 mK Dynamic measurementsSandwich is not a semi-infinite rod (TMC=const)Imposed temp. function TH is not sinusoidal (square heat wave)Simulation (MATLAB,pdepe):TH(t)=TH,meas(t)TMC=TMC,measxS=xSapphire

TC,sim=TC,measxthermSandwichs thermaldiffusivity a*

Studies of the Cryogenic Part with Load Lock SystemT. Eisel,CERN TE-CRG-CIAEgISNovember 11th, 2010 Page #Cryolab8ResultsCooling of electrically insulated high voltage electrodes down to 30 mK Dynamic measurements

Studies of the Cryogenic Part with Load Lock SystemT. Eisel,CERN TE-CRG-CIAEgISNovember 11th, 2010 Page #Cryolab

For temperatures > 30 mK an indium deposition improves the diffusivity significantly (about a factor of 2)The surface roughness influences the diffusivity only minor contrary to static measurements1; conclusion: heat transfer mechanisms of dynamic and static measurements are differentDiscussion/ conclusionCooling of electrically insulated high voltage electrodes down to 30 mK Dynamic measurements1 Eisel T., Bremer J., Burghart G., Feigl S., Haug F., Koettig T., Cooling of electrically insulated high voltage electrodes down to 30 mK. Proceedings of the twenty third cryogenic engineering conference, Poland; 2010.

Sandwichs thermal diffusivity is more than 6 orders of magnitude smaller than the thermal diffusivity of copper or sapphire thermal boundary resistanceThe diffusivity is not constant, it diminishes with reduced temperature thermal boundary resistance The fastest heat propagation could be achieved along a Sandwich using indium deposited and polished sapphire platesStudies of the Cryogenic Part with Load Lock SystemT. Eisel,CERN TE-CRG-CIAEgISNovember 11th, 2010 Page #Cryolab