The art of cryogenics: low-temperature experimental techniques

379 Pages·2008·6.02 MB·English

by  Guglielmo Ventura, Lara Risegari

The Art of Cryogenics
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The Art of Cryogenics
Low-Temperature Experimental Techniques
Guglielmo Ventura
and
Lara Risegari
Amsterdam•Boston•Heidelberg•London•NewYork•Oxford
Paris•SanDiego•SanFrancisco•Singapore•Sydney•Tokyo
Elsevier
LinacreHouse,JordanHill,OxfordOX28DP,UK
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Firstedition2008
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Contents
Preface xiii
PART I 1
1 Vacuum Techniques 3
1.1 Introduction 3
1.2 Vapour pressure 5
1.3 Mean free path and viscosity 6
1.4 Gas flow 7
1.4.1 Conductance of an orifice and of a pipe for molecular flow 9
1.4.2 Conductance of an orifice and of a pipe for viscous flow 10
1.5 Evacuation of a lumped volume 11
1.6 Vacuum pumps 12
1.6.1 Rotary vane oil-sealed mechanical pump 13
1.6.2 Booster pumps 14
1.6.3 Scroll pumps 15
1.6.4 Sorption pumps 17
1.6.5 Oil diffusion pumps 17
1.6.6 Turbomolecular pumps 20
1.6.7 Molecular drag pumps 22
1.7 Other vacuum components 23
1.8 Pressure gages 26
1.8.1 Total-pressure gages 26
1.8.2 McLeod gage 27
1.8.3 Bourdon gage 28
1.8.4 Diaphragm gage 28
1.8.5 Thermal conductivity gages 29
1.8.6 Hot cathode ionization gage 29
1.8.7 Cold cathode gage 31
1.9 Measurement of partial pressures 32
1.9.1 Leak detectors 32
References 33
v
vi Contents
PART II 35
2 Cryoliquids 37
2.1 Cryogenics: Introduction and history 37
2.2 Cryoliquids 40
2.2.1 Liquid oxygen and hydrogen 40
2.2.2 Liquid nitrogen 42
2.2.3 Liquid helium 43
2.2.4 Helium physics properties 45
2.2.4.1 Helium vapour pressure and latent heat
of evaporation 45
2.2.4.2 Helium specific heat 47
2.2.4.3 Transport properties of liquid 4He: thermal
conductivity and viscosity 51
References 53
3 Properties of Solids at Low Temperature 55
3.1 Introduction 55
3.2 Specific heat 56
3.3 Lattice specific heat 56
3.4 Electronic specific heat 58
3.5 Electronic specific heat in superconducting materials 59
3.6 Magnetic specific heat 62
3.7 Specific heat due to the amorphous state 66
3.8 Data of specific heat 69
3.9 Thermal expansion 71
3.10 Thermal conductivity 73
3.10.1 Phonons 75
3.10.2 Electron thermal conductivity 77
3.11 Superconducting metals 80
3.12 Data of low-temperature thermal conductivity 81
3.13 The Wiedemann–Franz law 83
References 84
4 Heat Transfer and Thermal Isolation 89
4.1 Introduction 89
4.2 Selection of materials of appropriate thermal conductivity 89
4.3 Heat switches 91
4.3.1 Gas heat switches 91
4.3.2 Superconducting heat switches 92
4.3.3 Other heat switches 93
4.4 Contact thermal resistance 94
References 100
Contents vii
PART III 103
5 Cooling Down to 0.3K 105
5.1 Introduction 106
5.2 Transport and storage vessels 106
5.3 Liquid 4He in the cryostats 107
5.3.1 Cool-down period 108
5.3.2 Constant temperature period 108
5.3.2.1 Heat conduction 108
5.3.2.2 Heat radiation 108
5.3.2.3 Conduction by gas particles 110
5.3.2.4 Thermoacoustic oscillations 111
5.4 4He cryostats 111
5.4.1 Cryostats for T>4(cid:2)2K 111
5.4.2 Cryostats for 1(cid:2)3K<T<4(cid:2)2K 112
5.5 3He cryostats 114
5.5.1 3He refrigerator with internal pump 115
5.6 Accessories 117
5.6.1 N transfer tubes 117
2
5.6.2 4He transfer tubes 117
5.6.3 Liquid-level detectors 119
5.7 Mechanical refrigerators 120
5.7.1 Introduction 120
5.7.2 Coolers using counterflow heat exchangers 121
5.7.2.1 Pressure drop 121
5.7.2.2 Heat transfer 121
5.7.2.3 Efficiency and length 122
5.7.2.4 Construction 123
5.7.2.5 Other liquefier details 124
5.7.3 The Collins helium liquefier 125
5.7.4 Klimenko cycle 125
5.7.5 Coolers using turbo-expanders 126
5.7.6 Brayton cycle 127
5.7.7 Coolers using regenerative heat exchangers 128
5.7.8 Philips Stirling cycle 128
5.7.9 Gifford–McMahon 130
5.8 Pulse tube refrigerators 131
5.8.1 Introduction 131
5.8.2 Two compression methods for the PTR 133
5.8.3 Simplified operation principle of PTRs 135
5.8.4 Cooling power 137
5.8.5 Multistage PTRs 139
References 139
viii Contents
6 Dilution Refrigerators 143
6.1 Introduction 143
6.2 Properties of 3He–4He liquid mixture 144
6.3 The classic DR 147
6.4 The J–T DR 153
6.5 Practical operations with a DR 156
6.6 DR in high magnetic fields 157
6.7 Dry DR 158
6.8 No-gravity dilution 158
References 160
7 Other Refrigerators 163
7.1 Introduction 163
7.2 Pomeranchuck refrigerator 163
7.2.1 The strange behaviour of 3He 164
7.3 Adiabatic demagnetization refrigerator 167
7.4 Adiabatic nuclear demagnetization 169
7.5 Electronic refrigeration 170
References 170
PART IV 173
8 Temperature Scales and Temperature Fixed Points 175
8.1 Introduction 175
8.2 Reference fixed points 176
8.3 The ITS 90 178
8.4 The provisional Low-Temperature Scale 2000 181
8.5 NBS-SRM 767a, 768 and SRD 1000 fixed point devices 184
8.6 APPENDIX: Superconductive transitions and influence
of purity and magnetic fields 187
References 190
9 Low-Temperature Thermometry 193
9.1 Introduction 193
9.2 Gas thermometry 194
9.2.1 Constant volume gas thermometry 195
9.2.2 Acoustic gas thermometry 196
9.2.3 Dielectric constant gas thermometry 197
9.3 Vapour pressure thermometry 198
9.4 3He melting curve thermometry 199
9.5 Thermocouples 200
Contents ix
9.6 Resistance thermometry 202
9.6.1 Metal thermistors 202
9.6.2 Semiconductors, carbon and metal oxide thermistors 203
9.6.2.1 Doped germanium resistors 204
9.6.2.2 Carbon resistors 205
9.6.2.3 Thick-film RuO resistors 206
2
9.6.2.4 Zirconium oxinitride 207
9.6.2.5 Junction diodes 208
9.6.3 Traps in resistance thermometry 208
9.7 Noise thermometry 211
9.8 Dielectric constant thermometry 212
9.9 Paramagnetic salt thermometry 215
9.10 Nuclear orientation thermometry 216
9.11 Magnetic thermometry with nuclear paramagnets 219
9.12 Coulomb blockade thermometry 219
References 221
10 Instrumentation for Cryogenics 225
10.1 Magnets 225
10.1.1 Superconducting magnets 225
10.1.2 Magnet wires 226
10.1.3 Magnet specifications 226
10.1.4 Persistent mode 227
10.1.5 Power supplies for magnets 228
10.2 Radio frequency shielding and filtering 228
10.2.1 Electric and magnetic fields 228
10.2.2 Superconducting shields 229
10.2.3 Electromagnetic interference filtering 229
10.3 Bridges 231
10.4 The synchronous demodulator (lock-in) 232
10.5 Temperature control 237
10.6 Low-noise cold amplifiers 238
References 240
PART V 243
11 Measurement of the Properties of Solids at Low Temperature 245
11.1 Introduction 245
11.2 Measurement of the thermal conductivity 246
11.3 Measurement of the thermal conductivity of A6061-T6 and A1050
between 4.2 and 77K 249
11.3.1 Introduction 249
11.3.2 Experiment and results 249