{
  "id": "2403.08141",
  "version": "v1",
  "published": "2024-03-13T00:00:35.000Z",
  "updated": "2024-03-13T00:00:35.000Z",
  "title": "Parallel Diffusion Coefficient of Energetic Charged Particles in the Inner Heliosphere from the Turbulent Magnetic Fields Measured by Parker Solar Probe",
  "authors": [
    "Xiaohang Chen",
    "Joe Giacalone",
    "Fan Guo",
    "Kristopher G. Klein"
  ],
  "comment": "Accepted to ApJ",
  "categories": [
    "astro-ph.SR",
    "physics.plasm-ph",
    "physics.space-ph"
  ],
  "abstract": "Diffusion coefficients of energetic charged particles in turbulent magnetic fields are a fundamental aspect of diffusive transport theory but remain incompletely understood. In this work, we use quasi-linear theory to evaluate the spatial variation of the parallel diffusion coefficient $\\kappa_\\parallel$ from the measured magnetic turbulence power spectra in the inner heliosphere. We consider the magnetic field and plasma velocity measurements from Parker Solar Probe made during Orbits 5-13. The parallel diffusion coefficient is calculated as a function of radial distance from 0.062 to 0.8 AU, and the particle energy from 100 keV to 1GeV. We find that $\\kappa_\\parallel$ increases exponentially with both heliocentric distance and energy of particles. The fluctuations in $\\kappa_\\parallel$ are related to the episodes of large-scale magnetic structures in the solar wind. By fitting the results, we also provide an empirical formula of $\\kappa_{\\parallel}=(5.16\\pm1.22) \\times 10^{18} \\: r^{1.17\\pm0.08} \\: E^{0.71\\pm 0.02} \\; (cm^2/s)$ in the inner heliosphere which can be used as a reference in studying the transport and acceleration of solar energetic particles as well as the modulation of cosmic rays.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-03-13T00:00:35.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "parallel diffusion coefficient",
      "turbulent magnetic fields",
      "parker solar probe",
      "energetic charged particles",
      "inner heliosphere"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}