Kurt UhligWalther Meissner Institute

Garching, Germany

50 Years of Dilution Refrigeration50 Years of Dilution Refrigeration, Manchester, 16 September 2015 , Manchester, 16 September 2015

1990: Patrick Pari, Adv Cryog Eng 35: 1079 first cryogen-free DR precooled by GM cryocooler

1999: delivery of PT4-05 (#2 in CRYOMECH production line)

2002: Cryogenics 42: 73 „ 3He/4He DR with pulse tube precooling “

2007: Prouvé et al., JLTP 148: 909„Pulse-Tube Dilution Refrigeration Below 10 mK“

heat leak:Q(tot) = 70 nW

GM-precool:Q(GM) = 170 nW

T(mc2) = 4.3 mK

„Cryogen-free“ dilution refrigerators

CryomechPT405

trap

PT1

PT2

IVC

double mc

3He melting curve therm.

Cryogenics 44 (2004) 53

cfhx

flow restriction

hx‘s

shield

„Cryogen-free“ dilution refrigerators

VeriCold Inc.:•no inner vacuum can (IVC)•big mixing chamber plate•separate pulse tubes from rotary valve•all electrical feedthroughs @ 300K•precool circuit•(or gas heat switches, BlueFors)

High refrigeration powers(2.5 mW @ 120 mK)(1.75 mW@100 mK)Superconducting magnets(up to 18 T)Clear shotsTop loadingBottom loading (cold sample exchange)

~ 75% of newly sold DRs are CF

Automatic cooldown

Cryomech PT405 RM:

1st stage: 32 K40 W@ 75 K2nd stage: 2.5 K0.5 W @4 K

4He-1K-stage:

Q = 100 mW @ 1.3 K(80 m3/h pump)T(min) = 1.05 K

DR-stage:

0.7 mW @ 100 mKT(min) = 4.0 mK(CMN + fixed point device)

PT405

CMN sc FPD

CF-DR with 1K-stage(exp. on sc quantum circuits)

Vibrational heat leak:

•run fridge at base temperature•fill 1K-stage with 4He(liq)•operate 1K-pot in single cycle mode•turn off pulse tube cryocooler•see if mixing chamber temperature drops•(and make sure, still temperature and inlet pressure remain unchanged)

Cryogenics !

J. Hoehne: arXiv: 1506.08856 (CEC/ICMC 2015)

J. Hoehne, Cryocoolers 18 (2014) 319

gear pump

el. motor

cylinder

pistoncooler

oil

pV - efficiency: η ~ 70%

90 mmν = 1 Hz

Thanks for your attention!

„Cryogen-free“ dilution refrigerators

Characteristics of dry fridge: Wide geometry, no He, no 1K-pot, automatic cooldown and warmup

2004:helium: 5 €/lpower 9c / kWhPTR: 25,000 €

compare withHe-cryostat20 l (liq) / day )

2015:helium: 7.50 €/lpower 0.201 €/kWhPTR: 33,500 €

amortization: 280 days 5kW-PTR (320 days 10 kW-PTR)

amortization:266 days 5kW-PTR(330 days 10kW-PTR)

AUTOMATION!

„Cryogen-free“ dilution refrigerators

J. Hoehne: arXiv: 1506.08856 (CEC/ICMC 2015)