Abstract

New developments in magnetic field sensors have opened up important applications. In this talk a summary of important applications is shown, from biomagnetic, geophysical, astronomical, and archeological exploration to as non-destructive testing and data storage. The field ranges and frequencies for these applications are summarized, and the various interactions of magnetic fields discussed. This leads to the various technologies for magnetometers, including inductive, ferromagnetic, semiconducting, superconducting, and spin resonance devices. For this introduction, and because a large range of magnetometers will be discussed, only a handful of the relevant properties are tabulated for each sensor type. This include (1) the state variable, e.g. the voltage, frequency, or current, (2) how it measures the magnetic field, i.e. vector or scalar, (3) the noise floor at 1 Hz, (4) Operating temperature, (5) the power required, and finally, (6) the form factor. A brief survey, starting with the SQUID magnetometers, is embarked on. With this discussion, some brief examples of spectral noise and the effect on the real-time signal observed is shown. In addition, examples of some of the specific types and advances in magnetometers is expounded on where appropriate. For example, at least three distinct types of resonance magnetometers and magneto-resistive magnetometers exist. These are summarized, however, details of operation are left for talks later in the week. Wherever disruptive technologies in this area exist, such as magneto-electric and hybrid superconductor-GMR devices, a brief introduction is given, and A review of standard technologies such as the Hall effect is presented, In summary, a comparison of sensor performance is analyzed, and the considerations for selection of various technologies is discussed.

Biography

David Pappas is a Physicist and Project Leader in the Quantum Measurements Group at the National Institute of Standards and Technology. He received a B.A. in Physics from the University of Colorado in Boulder in 1986. He then went to the University of California, Irvine where he received his M.S. and Ph.D. in 1990 working in the area of surface magnetism. At UCI he won an IBM Graduate Research Fellowship, and he went on to do post-doctoral work first at IBM Almaden Research Center and then at the Naval Research Laboratory as an Office of Naval Technology Research Fellow. David then taught and did research in the Physics Department at Virginia Commonwealth University as an Assistant Professor, where he won a National Science Foundation Young Investigator award. He has published over 80 papers, and is currently the Chair of the IEEE Rocky Mountain Magnetics Chapter.