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Mr. SQUID User's Guide Mr. SQUID® User's Guide Version 6.6 STAR Cryoelectronics, LLC 25 Bisbee Court, Suite A Santa Fe, NM 87508 U. S. A. ii ® Mr. SQUID User's Guide Manual written by Randy W. Simon, Michael J. Burns, Mark S. Colclough, Greg Zaharchuk, and Robin Cantor Advanced Experiments written by Michael J. Burns (Exp. 1-5) and Greg Zaharchuk (Exp. 6) Mr. SQUID® is a registered trademark of STAR Cryoelectronics, LLC Copyright © 1996 – 2012 STAR Cryoelectronics, LLC iii Mr. SQUID User’s Guide TABLE OF CONTENTS Technical Support .......................................................................................................................... vi Warranty ....................................................................................................................................... vii Safety Precautions ......................................................................................................................... vii 1 Introduction ..................................................................................................................... 1 2 The Mr. SQUID® System ............................................................................................... 5 2.1 System Components........................................................................................................ 5 2.2 Additional Equipment Required ..................................................................................... 5 3 Getting Started with Mr. SQUID® (New Users) ............................................................. 6 3.1 Setting Up the Mr. SQUID® System............................................................................... 6 3.2 Cooling the Mr. SQUID® Probe ..................................................................................... 8 3.3 Varying the Current Offset ............................................................................................. 9 3.4 Varying the Amplitude of the Sweep Output ................................................................. 9 3.5 Calculating the Current and Voltage............................................................................... 9 3.6 Observing V-Ι Characteristics using Mr. SQUID® ....................................................... 10 3.7 Observing V-Φ Characteristics using Mr. SQUID® ..................................................... 15 3.8 Additional SQUID Measurements ................................................................................ 18 3.9 Summary of Basic Experiments.................................................................................... 20 4 Getting Started with Mr. SQUID® (Advanced Users) .................................................. 22 4.1 Electronics Box Front Panel ......................................................................................... 22 4.2 Electronics Box Rear Panel .......................................................................................... 24 4.3 Observing V-Ι Characteristics using Mr. SQUID® (Advanced Users) ......................... 25 4.4 Observing V-Φ Characteristics using Mr. SQUID® (Advanced Users) ....................... 27 5 An Introduction to Superconductivity and SQUIDs ..................................................... 29 5.1 A Capsule History of Superconductivity ...................................................................... 29 5.2 Superconductivity: A Quantum Mechanical Phenomenon .......................................... 29 5.3 The Superconducting State ........................................................................................... 29 5.4 The Quantum of Flux .................................................................................................... 30 5.5 Superconducting Rings ................................................................................................. 31 5.6 Josephson Junctions ...................................................................................................... 32 5.7 The DC SQUID............................................................................................................. 33 5.8 Details of DC SQUID Operation .................................................................................. 34 STAR Cryoelectronics, LLC iv Mr. SQUID User’s Guide 5.9 SQUID Parameters........................................................................................................ 39 5.10 SQUID Operation ......................................................................................................... 41 5.11 Practical SQUID Magnetometers ................................................................................. 42 5.12 SQUID Applications ..................................................................................................... 44 5.13 A Brief History of SQUIDs .......................................................................................... 45 5.14 The SQUID in Mr. SQUID® ......................................................................................... 46 6 Troubleshooting and Getting Help ............................................................................... 49 6.1 Problems in V-I Mode ................................................................................................... 50 6.2 Problems in V-Φ Mode (Assuming Everything Works in V-I Mode) .......................... 51 6.3 Magnetic Flux Trapping in SQUIDs............................................................................. 51 6.4 Degaussing the Magnetic Shield ................................................................................... 52 6.5 RF Interference ............................................................................................................. 53 6.6 Customer Service .......................................................................................................... 55 7 Advanced Experiments ................................................................................................. 56 7.1 Resistance vs. Temperature of the YBCO SQUID ....................................................... 57 7.2 Building an Analog Flux-Locked Loop ........................................................................ 64 7.3 Using a Flux-Locked Loop as a Sensitive Voltmeter ................................................... 68 7.4 The AC Josephson Effect: Microwave-Induced (Shapiro) Steps at 77K and Determining h/e. ........................................................................................................... 72 7.5 Inductive Measurement of the Superconducting Transition Temperature of an HTS Film ............................................................................................................................... 78 7.6 SQUID Properties in Pumped Liquid Nitrogen ............................................................ 85 8 About STAR Cryoelectronics ....................................................................................... 89 9 Technical Specifications ............................................................................................... 90 9.1 Electronics..................................................................................................................... 90 9.2 Probe ............................................................................................................................. 90 9.3 Magnetic Shield ............................................................................................................ 90 9.4 RF Filter Module........................................................................................................... 91 9.5 Cable ............................................................................................................................. 91 9.6 Dewar ............................................................................................................................ 91 9.7 Rear Panel I/O Specifications ....................................................................................... 91 10 References ..................................................................................................................... 93 STAR Cryoelectronics, LLC v Mr. SQUID User’s Guide Revision Record Date Revision Description July 17, 2000 6.1 STAR Cryoelectronics Release January 11, 2002 6.1.1 Updated contact information April 26, 2002 6.2 Updated specifications May 10, 2002 6.2.1 Updated specifications August 8, 2003 6.2.2 Updated specifications September 8, 2007 6.3 Updated Sec. 3, Sec. 5, SQUID specs. August 17, 2009 6.4 Revised for EB-03 electronics August 13, 2011 6.5 Added rear panel I/O specifications Copyright © 2000 – 2011 by STAR Cryoelectronics, LLC, Santa Fe, NM 87508 All rights reserved. No part of this manual may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior written permission of STAR Cryoelectronics. STAR Cryoelectronics reserves the right to change the functions, features, or specifications of its products at any time, without notice. TECHNICAL SUPPORT If you have any questions or comments about this product or other products from STAR Cryoelectronics, please contact: STAR Cryoelectronics 25 Bisbee Court, Suite A Santa Fe, NM 87508 U. S. A. http://www.starcryo.com/ Technical Support: Tel.: (505) 424-6454 FAX: (505) 424-8225 Email: [email protected] STAR Cryoelectronics, LLC vi Mr. SQUID User’s Guide WARRANTY STAR Cryoelectronics Limited Warranty STAR Cryoelectronics warrants
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