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Tunnel Junction Refrigerators Cooling From 300 mK to 112 mK with Large Cooling Power

Tunnel Junction Refrigerators Cooling From 300 mK to 112 mK with Large Cooling Power. Galen O'Neil For Peter Lowell (his knee ). NIST Boulder NIS Team Peter Lowell Dan Schmidt Jason Underwood Joel Ullom. NIS Refrigerator. hot. (Al-Mn)Ox. Al. Al. I. Substrate (Si). cold. Al-Mn.

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Tunnel Junction Refrigerators Cooling From 300 mK to 112 mK with Large Cooling Power

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  1. Tunnel Junction Refrigerators Cooling From 300 mK to 112 mKwith Large Cooling Power Galen O'Neil For Peter Lowell (his knee ) NIST Boulder NIS Team Peter Lowell Dan Schmidt Jason Underwood Joel Ullom

  2. NIS Refrigerator hot (Al-Mn)Ox Al Al I Substrate (Si) cold Al-Mn Al-Mn SiO2 10 um hot Si hot I Junction Superconductor (Al) cold Normal Metal (AlMn) hot hot

  3. More options for refrigeration below 300 mK 2-stage 3He cheapest ~ 300 mK + ADR Moderate price 50 mK Dilution refrigerator Most expensive 10 mK NIS refrigerator cooling detectors 100 mK

  4. Previous State of the Art 320 mK 160 mK Tc=185mK Dissipating 22 pW 230 mK rest of chip = 260mK -NIS cooled X-Ray detector has best 6keV resolution with cryostat above 200mK: 9.4 eV @ 6keV -Representative of a class sensors that operate near 100mK N S cold hot A.M Clark, et al, Appl Phys Lett 86, 1734508 (2005)‏ N.M. Miller, et al, Appl Phys Lett 92, 163501 (2008)

  5. How does it work? Vbias=.5Δ/e eVbias BCS DOS BCS DOS BCS DOS

  6. Hot Electrons Tunnel Vbias=.9Δ/e eVbias BCS DOS BCS DOS

  7. Normal Metal Cools - Superconductor Heats Vbias=.9Δ/e eVbias BCS DOS BCS DOS

  8. Add a Heatsink (Quasiparticle Trap) Vbias=.9Δ/e eVbias no bias on heatsink junction BCS DOS BCS DOS

  9. NIS Refrigerator Geometry Al-Mn hot Al Al (Al-Mn)Ox I cold Al-Mn Al-Mn SiO2 hot Si

  10. Old Thermal Model IV Power NIS Junction Cooling Function of Tn I2R normal metal electrons superconductor (fixed at bath temperature) Payload Power Quasiparticle Return(Small Fraction of IV, Empirical) Electron-Phonon Coupling substrate/normal metal phonons (fixed at bath temperature)

  11. New Thermal Model with Heatsink IV Power Quasiparticle Trapping/ (Heatsink) NIS Junction Cooling Function of Tn,Ts I2R normal metal electrons normal metal trap electrons (T vs Position) superconductor (QP Density vs Position) Payload Power Electron-Phonon Coupling Quasiparticle Recombination Electron-Phonon Coupling substrate/normal metal phonons (fixed at bath temperature)

  12. Inside The Thermal Model x Al-Mn Al Al-Mn Al-Mn SiO2 Si quasiparticle:

  13. Predictions of Model Al-Mn hot (Al-Mn)Ox Al Al I cold Al-Mn Al-Mn SiO2 hot Si Previous 50nm Target 25nm

  14. Predictions of Model Al-Mn hot (Al-Mn)Ox Al Al I cold Al-Mn Al-Mn SiO2 hot Si Previous Overlayer Oxide (no overlayer trap) Target for overlayer 10 Wmm2

  15. Measured Cooling to 112 mK 300 mK ↓ 112 mK Record NIS Cooling (Large Junction) 2008 TNIS=TADR Sat July 30 2010

  16. Next Step:NIS Cooled Cryogenic Stage • 3mm chip -> 0.1uW @ 100 mK • 10 uW dissipated at 300mK

  17. NIS Junction Cooling • Function of Tn

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