On the Origin of Ultra High Energy Cosmic Rays

Fowler, T.K.; Colgate, S. A.; Li, H

doi:10.2172/963520

Cited by 2 publications

(22 citation statements)

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“…[9], and for fusion, in Refs. [12] and [13] and a paper in progress. Otherwise the main difference between the astrophysical dynamos and selfexcited spheromak dynamos for fusion concern the mission: in astrophysics, to explain jet/radiolobes as a failure of dynamo plasma confinement in the dynamo; in fusion, to achieve plasma confinement good enough to achieve nuclear ignition in a device smaller than tokamaks.…”

Section: Discussionmentioning

confidence: 99%

“…Refs. [11] and [12] use Eq. (10) to approximate the magnetic structure, giving simply Ψ TOR = (L/a) (lnR/a)Ψ POL with dynamo radius a, jet length L >> a, and radiolobe radius R ≈ L (confined by ambient pressure).…”

Section: Application To Accretion Disksmentioning

confidence: 99%

“…One could extend the coronal equilibrium model of Ref. [14] to the interior if, for example, the region interior to the corona is dominated by radiation pressure near the Eddington limit [8,12].…”

Section: Application To Accretion Disksmentioning

confidence: 99%

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Simple Model of the (alpha)(omega) Dynamo: Self-Excited Spheromaks

Fowler¹

2010

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The astrophysical αω dynamo converting angular momentum to magnetic energy can be interpreted as a self-excited Faraday dynamo together with magnetic relaxation coupling the dynamo poloidal field to the toroidal field produced by dynamo currents.Since both toroidal and poloidal fields are involved, the system can be modeled as helicity creation and transport, in a spheromak plasma configuration in quasi-equilibrium on the time scale of changes in magnetic energy. Neutral beams or plasma gun injection across field lines could create self-excited spheromaks in the laboratory.

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Section: Discussionmentioning

confidence: 99%

Section: Application To Accretion Disksmentioning

confidence: 99%

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Simple Model of the (alpha)(omega) Dynamo: Self-Excited Spheromaks

Fowler¹

2010

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“…In this section, we are mainly concerned with the central column of Figure 1, where magnetic relaxation by internal kink modes extending into the disk, discussed in Appendix B, can lead to a relaxed magnetic field with known profiles, hence describable by a 0-D model with the radius a, poloidal field B o and current I as parameters. The system evolution in time is dominated by inductance, the jet mass density being very low, just that needed to carry current ejected by an electrostatic sheath that forms at the disk surface at a location where the sheath voltage equals the energy required to escape gravity [6]. If collisions are negligible in the sheath, for a positively-charged disk the sheath current is a "runaway" ion beam with density n i given by:…”

Section: Accelerator Structurementioning

confidence: 99%

“…where <v> is the average ion speed carrying the current (→ c, the speed of light) and A the cross-sectional area. If collisions remain negligible in the jet, the runaway ion beam continues to carry the current in the jet, since relativistic electron (or electron-positron) current tends to be canceled in our fixed reference frame centered on the black hole, due to two-stream instability [6,12,13]. Higher density in laboratory jets is due to gas sources beyond the sheath.…”

Section: Accelerator Structurementioning

confidence: 99%

On the Origin of Ultra High Energy Cosmic Rays II

Fowler¹,

Colgate²,

Li³

et al. 2011

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We show that accretion disks around Active Galactic Nuclei (AGN's) could account for the enormous power in observed ultra high energy cosmic rays ≈ 10 20 eV (UHE's). In our model, cosmic rays are produced by quasi-steady acceleration of ions in magnetic structures previously proposed to explain jets around Active Galactic Nuclei (AGN's) with supermassive black holes. Steady acceleration requires that an AGN accretion disk act as a dynamo, which we show to follow from a modified Standard Model in which the magnetic torque of the dynamo replaces viscosity as the dominant mechanism accounting for angular momentum conservation during accretion. A black hole of mass M BH produces a steady dynamo voltage V ∝ √M BH giving V ≈ 10 20 volts for M BH ≈ 10 8 solar masses. The voltage V reappears as an inductive electric field at the advancing nose of a dynamo-driven jet, where plasma instability inherent in collisionless runaway acceleration allows ions to be steadily accelerated to energies ≈ V, finally ejected as cosmic rays. Transient events can produce much higher energies. The predicted disk radiation is similar to the Standard Model. Unique predictions concern the remarkable collimation of jets and emissions from the jet/radiolobe structure. Given M BH and the accretion rate, the model makes 7 predictions roughly consistent with data: (1) the jet length; (2) the jet radius; (3) the steady-state cosmic ray energy spectrum; (4) the maximum energy in this spectrum; (5) the UHE cosmic ray intensity on Earth; (6) electron synchrotron wavelengths; and (7) the power in synchrotron radiation. These qualitative successes motivate new computer simulations, experiments and data analysis to provide a quantitative verification of the model.

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On the Origin of Ultra High Energy Cosmic Rays

Cited by 2 publications

References 0 publications

Simple Model of the (alpha)(omega) Dynamo: Self-Excited Spheromaks

Simple Model of the (alpha)(omega) Dynamo: Self-Excited Spheromaks

On the Origin of Ultra High Energy Cosmic Rays II

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