High Magnetic Field Science and Its Application in the United States Current Status and Future Directions (2013) / Chapter Skim
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Appendix E: Glossary
Appendix E: Glossary
Pages 185-195
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From page 185... ...
Bitter's design meets the high conductivity and cooling requirements of high-field resistive magnets using perforated copper plates that are sandwiched between insulating layers, a small region of electrical contact being allowed between plates so that current can flow from one plate to the next. Electrical current flows through the resulting copper spiral, and coolant flows through perforations in the conductors, which are aligned vertically.
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From page 186... ...
A Cooper pair consists of two electrons that are paired together into a new state with zero net charge and angular momentum. Below the superconducting transi tion temperature, Cooper pairs form a condensate -- a macroscopically occupied single quantum state -- in which current flows without resistance.
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From page 187... ...
cyclotron frequency: Charged carriers of all kinds follow cyclotron-like spiral trajectories in strong magnetic fields, with a frequency proportional to the field strength. In doped semiconductors and metals, measurements of the cyclotron frequency give information about the effective mass of the mobile carriers.
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From page 188... ...
mass spectrometry: FT ICR is a technique in which the mass-to-charge ratios of charged particles, espe cially molecular ions, are measured from the frequencies of their cyclotron motions in a strong magnetic field. Compared with other forms of mass spectrometry, FT ICR has the highest demonstrated precision and resolution, making it the method of choice for complex mixtures of molecules and for distinguishing among chemi cal species with nominally identical masses but different elemental compositions.
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From page 189... ...
The resistive portion operates as an insert to the superconducting magnet and produces the portion of the field that exceeds the critical current and field limits of the superconducting magnet. hybrid magnet, series-connected: Hybrid magnet system where the current sup plied to the resistive insert travels first through the superconducting outer magnet.
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From page 190... ...
magnetoresistance: In some materials, electrical resistance depends dramatically on external magnetic field. Antiferromagnetically coupled magnetic layers sepa rated by nonmagnetic spacers can display an extreme form of magnetoresistance called giant magnetoresistance, which is taken advantage of in the magnetic sensors used in high-density disk drives.
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From page 191... ...
National High Magnetic Field Laboratory (NHMFL) : National laboratory for the production of high and specialized magnetic fields for scientific research.
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From page 192... ...
pulsed-field magnet: Resistive magnet designed to provide transient magnetic fields, often for durations as short as microseconds but occasionally for as long as several seconds. Because it is active for only short times, a pulsed magnet uses less power and needs less cooling than a dc magnet of similar bore and maximum field strength.
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From page 193... ...
However, it was later observed that certain two dimensional semiconducting devices display precisely quantized plateaus in their Hall resistance -- that is, the ratio of Hall voltage to current -- which reflect the tuning of charge carrier occupancy states by the external magnetic field.
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From page 194... ...
It is characterized by the complete loss of electrical resistance and the complete expulsion of weak externally applied magnetic fields (the Meissner effect)
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From page 195... ...
See preceeding entry, HTS. synchrotron light source: Relativistic charged particles traveling in circular trajec tories emit electromagnetic radiation, known as synchrotron radiation.
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