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1 The Spinning Magnet Accelerator Cosmic CERNs and SLACs Robert Sheldon April 12, 2001
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2 Space Plasma Cyclotrons
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3/27 The "resonance condition for a cyclotron and the need for synchronization. u The maximum energy determined by maximum gyroradius of pole magnet u Center feed, rim exit. u Dipole=cyclotron u but NOT a betatron. The Synchro-Cyclotron
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4/27 Drift Motion in B-field Gradients x
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5/27 The Stochastic Dipole Cyclotron u Universe has dipoles. u Drift trapping more robust than gyrotrap because of edges. u Stochastically driven has power at all freq. u Adiabatic heating from inward diffusion (3rd invariant violation). u Adiabatic central heating--> escaping flux is cooler. u Rim feed, center exit. u The center is filled with the magnet, limiting the energy. u Diffusion rate slows near the center, limiting the power. PROCON
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6/27 Insufficiency of the SDC Although the radiation belts of the earth have 10 s MeV particles, either GeV s precipitate into the center, or keV s adiabatically escape, cooling off. From a Mars vantage point, the Earth dipole is a weak source of keV particles and atoms. Nor does adiabatic heating explain power law tails. The Dipole is a better trap than accelerator.
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7/27 MeV electrons 10/14/96
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8/27 1 MeV electron in T96 Cusp
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9/27 The Quadrupole Cusp u 2-Dipole interactions = Quadrupole. A Dipole embedded in flowing plasma creates a quadrupole cusp. u How likely? About like binary stars. u Quadrupole is both a drift+gyro trap. u Q is center feed, rim exit. Hi E escape. u Q has no center magnet permitting higher maximum energies. u Q is NOT adiabatic==> chaotic accel!
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10/27 Quadrupole Cosmic Scales u Planetary Magnetospheres u Stellar Heliospheres u Binary stars u Galactic magnetic fields u Galaxy clusters u keV (Mercury) to MeV (Jupiter) u 10 - 100 MeV as observed at Sun u 1-10 GeV u 10-100 GeV ? u TeV?
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11 Plasma Linear Accelerators
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13/27 Parallel Electric Fields l Whipple, JGR 1977. Ne = Ni, quasi-neutrality n kT e || E
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14/27 Heuristics for Parallel-Efield
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15/27 High Injection Density in Storms
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16/27 Necessary Conditions u Inhomogeneous strong B-field such that grad-B drifts dominate over ExB Dipole field! Ubiquitous u Source of hot plasma Injected directly (accretion disks) Convected from elsewhere (plasmasheet) u Spinning central magnet? u Result: Rim feed, axial exit accelerator. Efficient
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17/27 Herbig-Haro Objects: Stars with Accretion Disks HH30
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18/27 Blazar and Schematic Jet
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19/27 Quasar & Microquasar Jets Cygnus A 3C273
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20/27 Quadrupole Electric Field: 1st Excited State of a Dipole B-field + + + + - - - -
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21/27 Can SLAC power jets? u The maximum electric field of such a system is limited by 2nd order forces ((FXB) X B). Using some typical numbers for YSO for magnetic field strength, we get limiting energies of keV - MeV. u Applying same formula to quasar jets, we get ~1 GeV. Precisely the value that explains observations! u Q: What does a black hole magnetosphere look like? How does plasma affect equil.?
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22/27 Preliminary Conclusions u Both mechanisms are topological Ubiquitous. Scale to all sizes. u Quadrupole cyclotrons = 2 dipoles Planets embedded in flowing plasma Opposing magnetic fields, e.g. binary stars Stars (galaxies) moving through a plasma background u Jets =accretion disks + spinning B-fields. YSO, AGN, micro-quasars,Herbig-Haro Earth has half an accretion disk=plasmasheet
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23 The UAH Spinning Terrella Accelerator
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24/27 Experimental Setup u Bell jar, oil roughing pump, HV power supply, Nd-B ceramic magnet u Needle valve used to control the pressure from 10-400 mTorr u Simple
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25/27 Negatively Biased Magnet
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26/27 Arcs and Sparks
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27/27 Characteristics of Discharge u KeV of Voltage u Discharge lasts 30 microseconds u Calculated milliCoulombs of charge u Estimated nF capacitance of magnetic field u In better vacuum (or collisionless plasma) potentials are limited by 2 nd order plasma drifts u Result: Space charge accelerator
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28/27 Some References u Sheldon & Spurrier, "The Spinning Terrella Experiment", Phys. Plasmas, 8, 1111-1118, 2001. u Sheldon, "The Bimodal Magnetosphere", Adv. Sp. Res., 25, 2347-2356, 2000. u Sheldon, Spence & Fennel, "Observation of 40keV field-aligned beams", Geophys. Res. Lett. 25, 1617-1620, 1998. u All at: http://cspar181.uah.edu/RbS/http://cspar181.uah.edu/RbS/
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