The Physics of Pulsar Magnetospheres June 6th 2016 - NASA GSFC - - PowerPoint PPT Presentation

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The Physics of Pulsar Magnetospheres June 6th 2016 - NASA GSFC - - PowerPoint PPT Presentation

Jun 24, 2023 127 likes •359 views

The Physics of Pulsar Magnetospheres June 6th 2016 - NASA GSFC Developing of a specialized Particle-In-Cell code to study Pulsar Magnetospheres Gabriele Brambilla NASA GSFC, Universit degli Studi di Milano Im a grad student and I work

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Developing of a specialized Particle-In-Cell code to study Pulsar Magnetospheres The Physics of Pulsar Magnetospheres

June 6th 2016 - NASA GSFC

Gabriele Brambilla

NASA GSFC, Università degli Studi di Milano

I’m a grad student and I work with: Alice Harding Andrey Timokhin Constantinos Kalapotharakos Demosthenes Kazanas

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In PIC codes, particles moved by the fields form the currents that act on the fields themselves

Birdsall & Langdon 1985 Plasma Physics via Computer Simulation (New York: McGraw-Hill)

3D Cartesian

Electromagnetic Relativistic pusher Parallelized

PML

perfectly matched layer

Domain size

physical 3.0 RLC with PML 3.6 RLC

Resolution (max)

7203 cells 1.5 109 particles All the simulation run on Discover - NASA NCCS Most of the plots and videos are done with VisIt (produced by LLNL)

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We tested our code with typical plasma problems, like the two stream instability

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We tested our code with typical plasma problems, like the two stream instability

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We inject neutral plasma everywhere until we reach a lower magnetization limit inside a fixed radius

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[arbitrary units]

We inject neutral plasma everywhere until we reach a lower magnetization limit inside a fixed radius

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We inject neutral plasma everywhere until we reach a lower magnetization limit inside a fixed radius

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[arbitrary units]

We inject neutral plasma everywhere until we reach a lower magnetization limit inside a fixed radius

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We reached a configuration similar to the force free gradually changing the injection parameters

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In the force free solution the parallel electric field is screened except for the current sheet

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The currents flow on the current sheet and from the polar cap

[arbitrary units]

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It is necessary to keep the magnetization high to resemble the real pulsar behavior

Magnetization

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In PIC simulations the multiplicity is lower than in a real pulsar

Multiplicity

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We can look at the different contribution of electrons and positrons to the current

Positrons Electrons

[arbitrary units]

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… And we can see where electrons mostly contribute to the current and where positrons do

[arbitrary units]

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We can also look at the direction of the flows

[arbitrary units]

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There are zones in which the flows counter stream and others in which they flow in the same direction

[arbitrary units]

J

Positrons Electrons

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Looking at the energy of the particles we see the most energetic flow in the branches of the current sheet

[arbitrary units] [arbitrary units] [arbitrary units]

charge

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The knowledge of the particle energy distribution is limited by the noise and the magnetic field

maximum noise

  • pen field voltage limit
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In the whole 3D structure the most energetic particles flow out on the current sheet

corotating frame inertial frame

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