The SQUID Handbook: Fundamentals and Technology of SQUIDs and SQUID Systems

The SQUID Handbook Vol. I......Page 4
Contents......Page 8
Preface......Page 14
List of Contributors......Page 18
1 Introduction......Page 20
1.1 The Beginning......Page 21
1.2 Subsequent Developments......Page 24
1.3 The dc SQUID: A First Look......Page 26
1.4 The rf SQUID: A First Look......Page 31
1.5 Cryogenics and Systems......Page 35
1.6 Instruments: Amplifiers, Magnetometers and Gradiometers......Page 36
1.7 Applications......Page 40
1.8 Challenges and Perspectives......Page 43
1.9 Acknowledgment......Page 45
2 SQUID Theory......Page 48
2.1 Josephson Junctions......Page 49
2.1.1 RCSJ Model......Page 50
2.1.2 Thermal Noise......Page 56
2.1.3 The 1/ƒ Noise (I(0), R fluctuations)......Page 60
2.2.1 Introduction......Page 62
2.2.2 Basic Equations, dc SQUID Potential......Page 63
2.2.3.1 General Considerations......Page 69
2.2.3.2 Numerical Simulations (Langevin Equation)......Page 72
2.2.3.3 Analytical Theory of the dc SQUID......Page 78
2.2.4 Effect of Asymmetry......Page 84
2.3.1 Introduction......Page 89
2.3.2 SQUID Potential and the Equation of Motion for the Phase Difference......Page 91
2.3.3 Unitary Theory for Output Signal and Noise......Page 95
2.3.4.1 Introduction......Page 102
2.3.4.2 Adiabatic Operation; Hysteretic Phase Diagram......Page 103
2.3.4.3 Non-adiabatic Regime......Page 105
3 SQUID Fabrication Technology......Page 112
3.1 Junction Electrode Materials and Tunnel Barriers......Page 113
3.2.1 Refractory Junction Electrodes......Page 115
3.2.2 Tunnel Barrier Technology......Page 116
3.2.3 Deposition Techniques......Page 117
3.2.4 Junction Definition......Page 120
3.2.5 Dielectric Insulation......Page 121
3.2.6 Patterning Techniques......Page 122
3.2.8 Integrated SQUID Fabrication Process......Page 124
3.3.1 General Requirements and Problems......Page 126
3.3.2 Thin-film Deposition......Page 127
3.3.3 Patterning Techniques......Page 129
3.3.4 Junction Fabrication......Page 131
3.3.5 Fabrication of Single-layer Devices......Page 134
3.3.6 Fabrication of Multilayer Devices......Page 135
3.4 Future Trends......Page 137
4 SQUID Electronics......Page 146
4.2.1 Linearization of the Transfer Function......Page 147
4.2.2 Noise and Dynamic Behavior......Page 150
4.2.3 Integrator Types......Page 154
4.3.1 Fundamentals......Page 156
4.3.2.1 Flux Modulation......Page 158
4.3.2.2 Additional Positive Feedback......Page 160
4.3.3 Methods to Suppress 1/ƒ Noise......Page 162
4.3.4.1 Two–stage Configuration......Page 167
4.3.4.2 Series SQUID Arrays......Page 168
4.3.4.3 Relaxation Oscillation SQUIDs......Page 169
4.3.4.4 Digital SQUIDs......Page 171
4.4.2 Basic Building Blocks of rf SQUID Readout Electronics......Page 174
4.4.3 Construction of the Tank Circuit......Page 176
4.4.4 Coupling of the Tank Circuit to the Transmission Line......Page 178
4.4.5 Cryogenic Preamplifiers......Page 179
4.4.6 Optimization for Maximum Sensitivity......Page 181
4.4.7 Multiplexed Readouts for Multichannel rf SQUID Systems......Page 183
4.5 Trends in SQUID Electronics......Page 184
5 Practical DC SQUIDS: Configuration and Performance......Page 190
5.1 Introduction......Page 191
5.2.1 Uncoupled SQUIDs......Page 194
5.2.2 Coupled SQUIDs......Page 196
5.3.1 Overview......Page 205
5.3.2 Magnetometers for High Spatial Resolution......Page 206
5.3.3 Magnetometers for High Field Resolution......Page 207
5.4.1 Overview......Page 212
5.4.2 Thin-Film Planar Gradiometers......Page 214
5.4.3 Wire-Wound Axial Gradiometers......Page 217
5.5.2 Critical Current Fluctuations......Page 219
5.5.3 Thermally Activated Motion of Vortices......Page 220
5.5.4 Generation of vortices......Page 222
5.5.5.2 Vortex pinning......Page 224
5.5.5.3 Narrow Linewidth Device Structures......Page 225
5.5.5.4 Flux Dams......Page 226
5.6.1 Hysteresis......Page 227
5.6.2 Radio-Frequency Interference......Page 228
5.6.3 Temperature Fluctuations and Drift......Page 229
6 Practical RF SQUIDs: Configuration and Performance......Page 238
6.2.1 Practical Device Optimization......Page 239
6.2.2.1 Low-Temperature Bulk Magnetometers......Page 242
6.2.2.2 Low-Temperature Thin-Film Magnetometers......Page 245
6.2.3.1 Technological Limitations......Page 247
6.2.3.3 Early Thin-Film High-T(c) Magnetometers......Page 248
6.2.3.4 Magnetometers with Coplanar Resonators......Page 249
6.2.3.5 Magnetometers with Dielectric Resonators......Page 253
6.2.3.6 Thin-Film HTS Magnetometers with Flux Transformers......Page 254
6.3.2.1 Hardware rf SQUID Gradiometers......Page 255
6.4 Low-Frequency Excess Noise in rf SQUIDs......Page 256
6.5 Response of rf SQUIDs to High-Frequency Electromagnetic Interference......Page 258
6.6 Characterization and Adjustment of rf SQUIDs......Page 260
6.7 The rf SQUID versus the dc SQUID......Page 263
6.8 Concluding Remarks and Outlook......Page 265
7 SQUID System Issues......Page 270
7.1 Introduction......Page 273
7.2.1 Introduction......Page 274
7.2.2 Liquid Cryogen Cooling (Cryostats)......Page 275
7.2.3.1 Introduction......Page 277
7.2.3.2 Joule–Thomson Coolers......Page 278
7.2.3.3 Stirling Coolers......Page 279
7.2.3.4 Gifford–McMahon Coolers......Page 280
7.2.3.5 Pulse-tube Coolers......Page 281
7.2.3.6 Comparison of Cryocoolers......Page 283
7.2.3.7 Trends in Cryocooling......Page 284
7.2.4 Cryostat or Cryocooler?......Page 285
7.2.5.1 Interference Mechanisms......Page 286
7.2.5.3 Space Separation......Page 287
7.2.5.5 Noise Suppression Techniques......Page 288
7.2.6 Material Properties......Page 289
7.3.1.1 Introduction to Shielding Effectiveness......Page 291
7.3.1.2 Absorption......Page 292
7.3.1.3 Reflection......Page 293
7.3.1.4 High-frequency Shielding......Page 295
7.3.1.5 Low-frequency Shielding......Page 296
7.3.1.7 Determination of Low-frequency Shielding, Filtering or Noise Cancellation Requirements......Page 300
7.3.2.1 RF Screening of Electronics......Page 302
7.3.2.2 Cables and Conductors......Page 303
7.3.2.3 Cable Junctions, Terminations, Connectors and Grounding......Page 304
7.3.2.4 Crosstalk......Page 305
7.3.2.5 Power Consumption and Supply......Page 306
7.4.1 Introduction......Page 308
7.4.3 Dynamic Range, Accuracy and Linearity......Page 309
7.4.4 Sampling Rate and Signal Conditioning......Page 310
7.5.1 Introduction......Page 311
7.5.2.2 Transfer Coefficient......Page 312
7.5.2.4 Effective Volume of a Gradiometer......Page 313
7.5.2.5 SQUID Noise and Bandwidth Measurements......Page 314
7.5.2.7 Slew Rate......Page 315
7.5.2.8 Nonlinearity......Page 316
7.5.3.1 Introduction......Page 317
7.5.3.3 Field-removed (FR) Characterization......Page 318
7.5.4.1 Setting up Calibration Fields......Page 320
7.5.5.2 SQUID or Flux Jumps......Page 324
7.5.5.5 Adequate Shielding of the Cryostat......Page 326
7.5.5.7 Mechanical Vibration......Page 327
7.6.1 Introduction......Page 328
7.6.2 Signals Acting on SQUID Systems......Page 329
7.6.3.1 Environmental Noise in Stationary Applications......Page 330
7.7.2 Active Shielding......Page 334
7.7.3 Noise Cancellation by Primary Sensors......Page 335
7.7.4.1 Introduction......Page 338
7.7.4.2 Static Systems......Page 342
7.7.4.3 Mobile Systems......Page 349
7.7.5 Noise Cancellation Without the References......Page 351
7.8.2 Static SQUID Systems......Page 354
7.8.3 Mobile SQUID Systems......Page 358
7.8.4 Summary of Parameters......Page 361
7.9 Concluding Remarks and System Trends......Page 363
Appendix 1......Page 376
Appendix 2......Page 386
Index......Page 402