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# coding: utf-8 |
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# Copyright (c) 2020 Stefan Bender |
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# |
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# This file is part of pyeppaurora. |
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# pyeppaurora is free software: you can redistribute it or modify |
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# it under the terms of the GNU General Public License as published |
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# by the Free Software Foundation, version 2. |
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# See accompanying LICENSE file or http://www.gnu.org/licenses/gpl-2.0.html. |
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"""Particle precipitation spectra |
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""" |
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import numpy as np |
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__all__ = [ |
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"maxwell_general", |
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"pflux_maxwell", |
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] |
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def maxwell_general(en, en_0=10.): |
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r"""Maxwell number flux spectrum as in Fang2008 [1] |
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Defined in Fang et al., JGR 2008, Eq. (1), |
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normalized to :math:`\int_0^\infty \phi(E) \text{d}E = 1`. |
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Parameters |
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---------- |
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en: float or array_like (N,) |
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Energy in [keV] |
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en_0: float, optional |
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Characteristic energy in [keV], i.e. mode of the distribution. |
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Default: 10 keV |
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Returns |
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------- |
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phi: float or array_like (N,) |
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Normalized differential hemispherical number flux at `en` in [keV-1 cm-2 s-1] |
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([keV] or scaled by 1 keV-2 cm-2 s-1, e.g.). |
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""" |
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return en / en_0**2 * np.exp(-en / en_0) |
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def pflux_maxwell(en, en_0=10.): |
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r"""Maxwell particle flux spectrum as in Fang2008 [1] |
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Defined in Fang et al., JGR 2008, Eq. (1). |
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The total precipitating energy flux is fixed to 1 keV cm-2 s-1, |
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multiply by Q_0 [keV cm-2 s-1] to scale the particle flux. |
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Normalized to :math:`\int_0^\infty \phi(E) E \text{d}E = 1`. |
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Parameters |
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---------- |
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en: float or array_like (N,) |
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Energy in [keV] |
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en_0: float, optional |
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Characteristic energy in [keV], i.e. mode of the distribution. |
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Default: 10 keV. |
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Returns |
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------- |
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phi: float or array_like (N,) |
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Hemispherical differential particle flux at `en` in [keV-1 cm-2 s-1] |
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([kev-2] scaled by unit energy flux). |
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""" |
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return 0.5 / en_0 * maxwell_general(en, en_0) |
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st-bender /
pyeppaurora
