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A Particle-In-Cell Code to Study Astrophysical Plasma

The production of magnetic field due to counter-streaming electron-positron pair plasma beam. The result is obtained from the Shakti code. The blue and red circles represent electrons and positrons, respectively. Grid distribution is 200x200, where each cell has 8 particles per cell per species in each beam. A second-order shape function for each particle is used for current deposition.

'Shakti' is a multidimensional electromagnetic code that utilizes the Particle-In-Cell (PIC) method to study plasmas, with applications ranging from laboratory experiments to high-energy astrophysical phenomena.

Why a new code?

The PIC methods have diverse applications. However, despite decades of effort, many available codes remain difficult to use. The challenges include: 1) limited adaptability for user-defined modules, 2) inflexible simulation environment for setting up new problems, and 3) poor documentation. The Shakti code addresses these challenges by providing a modular, multidimensional, and user-friendly framework.

Shakti began as a self-tutorial project and has evolved into a robust numerical tool. The current version of the Shakti code supports one, two, and three dimensions in Cartesian geometry and is extensible to support different geometries.

The Shakti code is highly modular, supports multi-species, different distribution functions for each species (e.g., Maxwell-Boltzmann/Monoenergetic/power-law distribution), and higher-order shape functions. The code can be run on both single and multi-processors using commonly used compilers such as gcc or mpicc. While the current application focus is on the collisionless regime, where charged particles interact collectively through the electromagnetic field, instead of Coulomb interactions, the Coulomb interactions can be implemented. To explore sample test problems, click on "TestProblems". This code is currently in the development stage, to be released publicly soon.

F. Nonresonant streaming instability

Super-Alfvenic drift of relativistic particles in a nonrelativistic electron-proton plasma (this test includes three species)

E. Magnetic Reconnection

Magnetic reconnection in a highly magnetized electron-positron plasma

D. Twostream instability

Counterstreaming two beams made of electron-positron pair

C. Weibel Instability

Counter streaming beams made of electron-positrons (in-plane flow)

Counter streaming beams made of electron-positrons (out-of-plane flow)

B. Plasma Oscillation

Oscillation of electrons in electron-proton plasma

A. Charge conservation

This link is under construction.

This code is written by Siddhartha Gupta, a Postdoctoral Research Associate in the dept of Astrophysical Sciences at Princeton University. Click here to see his personal page.

Acknowledgement

SG acknowledges all members of the plasma group at the University of Chicago and Princeton University whose discussions in various forms inspired the creation of this code.