{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "\n",
    "Langmuir probe data analysis\n",
    "============================\n",
    "\n",
    "Let's analyze a few Langmuir probe characteristics using the\n",
    "`diagnostics.langmuir` subpackage. First we need to import the module and some\n",
    "basics.\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "jupyter": {
     "outputs_hidden": false
    }
   },
   "outputs": [],
   "source": [
    "%matplotlib inline\n",
    "\n",
    "import astropy.units as u\n",
    "import matplotlib.pyplot as plt\n",
    "import numpy as np\n",
    "import os\n",
    "\n",
    "from pprint import pprint\n",
    "\n",
    "from plasmapy.diagnostics.langmuir import Characteristic, swept_probe_analysis"
   ]
  },
  {
   "cell_type": "raw",
   "metadata": {
    "raw_mimetype": "text/restructuredtext"
   },
   "source": [
    "The first characteristic we analyze is a simple single-probe measurement in\n",
    "a low (ion) temperature, low density plasma with a cylindrical probe. This\n",
    "allows us to utilize OML theory implemented in :func:`~plasmapy.diagnostics.langmuir.swept_probe_analysis`.\n",
    "The data has been preprocessed with some smoothing, which allows us to obtain\n",
    "a Electron Energy Distribution Function (EEDF) as well."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "jupyter": {
     "outputs_hidden": false
    }
   },
   "outputs": [],
   "source": [
    "# Load the bias and current values stored in the .p pickle file.\n",
    "path = os.path.join(\"langmuir_samples\", \"Beckers2017.npy\")\n",
    "bias, current = np.load(path)\n",
    "\n",
    "# Create the Characteristic object, taking into account the correct units\n",
    "characteristic = Characteristic(u.Quantity(bias,  u.V),\n",
    "                                u.Quantity(current, u.A))\n",
    "\n",
    "# Calculate the cylindrical probe surface area\n",
    "probe_length = 1.145 * u.mm\n",
    "probe_diameter = 1.57 * u.mm\n",
    "probe_area = (probe_length * np.pi * probe_diameter +\n",
    "              np.pi * 0.25 * probe_diameter**2)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Now we can actually perform the analysis. Since the plasma is in Helium an\n",
    "ion mass number of 4 is entered. The results are visualized and the obtained\n",
    "EEDF is also shown.\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "jupyter": {
     "outputs_hidden": false
    },
    "nbsphinx-thumbnail": {
     "output-index": 2
    }
   },
   "outputs": [],
   "source": [
    "pprint(swept_probe_analysis(characteristic,\n",
    "                           probe_area, 'He-4+',\n",
    "                           visualize=True,\n",
    "                           plot_EEDF=True))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The cyan and yellow lines indicate the fitted electron and ion currents,\n",
    "respectively. The green line is the sum of these and agrees nicely with the\n",
    "data. This indicates a successful analysis.\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The next sample probe data is provided by David Pace. It is also obtained\n",
    "from a low relatively ion temperature and density plasma, in Argon.\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "jupyter": {
     "outputs_hidden": false
    }
   },
   "outputs": [],
   "source": [
    "# Load the data from a file and create the Characteristic object\n",
    "path = os.path.join(\"langmuir_samples\", \"Pace2015.npy\")\n",
    "bias, current = np.load(path)\n",
    "characteristic = Characteristic(u.Quantity(bias, u.V),\n",
    "                                u.Quantity(current, u.A))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Initially the electrons are assumed to be Maxwellian. To check this the fit\n",
    "of the electron growth region will be plotted.\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "jupyter": {
     "outputs_hidden": false
    }
   },
   "outputs": [],
   "source": [
    "swept_probe_analysis(characteristic,\n",
    "                     0.738 * u.cm**2,\n",
    "                     'Ar-40 1+',\n",
    "                     bimaxwellian=False,\n",
    "                     plot_electron_fit=True)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "It can be seen that this plasma is slightly bi-Maxwellian, as there are two\n",
    "distinct slopes in the exponential section. The analysis is now performed\n",
    "with bimaxwellian set to True, which yields improved results.\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "jupyter": {
     "outputs_hidden": false
    }
   },
   "outputs": [],
   "source": [
    "pprint(swept_probe_analysis(characteristic,\n",
    "                           0.738 * u.cm**2,\n",
    "                           'Ar-40 1+',\n",
    "                           bimaxwellian=True,\n",
    "                           visualize=True,\n",
    "                           plot_electron_fit=True))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The probe current resolution of the raw data is relatively poor, but the\n",
    "analysis still performs well in the ion current region. The bi-Maxwellian\n",
    "properties are not significant but do make a difference. Check this analysis\n",
    "without setting `bimaxwellian` to True!\n",
    "This is reflected in the results, which indicate that the temperatures of\n",
    "the cold and hot electron population are indeed different, but relatively\n",
    "close.\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "This Helium plasma is fully bi-Maxwellian.\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "jupyter": {
     "outputs_hidden": false
    }
   },
   "outputs": [],
   "source": [
    "# Import probe data and calculate probe surface area.\n",
    "path = os.path.join(\"langmuir_samples\", \"Beckers2017b.npy\")\n",
    "bias, current = np.load(path)\n",
    "characteristic = Characteristic(u.Quantity(bias, u.V),\n",
    "                                u.Quantity(current, u.A))\n",
    "probe_length = 1.145 * u.mm\n",
    "probe_diameter = 1.57 * u.mm\n",
    "probe_area = (probe_length * np.pi * probe_diameter +\n",
    "              np.pi * 0.25 * probe_diameter**2)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "`plot_electron_fit` is set to True to check the bi-Maxwellian properties.\n",
    "The fit converges nicely to the two slopes of the electron growth region.\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false,
    "jupyter": {
     "outputs_hidden": false
    }
   },
   "outputs": [],
   "source": [
    "pprint(swept_probe_analysis(characteristic,\n",
    "                           probe_area,\n",
    "                           'He-4+',\n",
    "                           bimaxwellian=True,\n",
    "                           plot_electron_fit=True,\n",
    "                           visualize=True))"
   ]
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Python 3",
   "language": "python",
   "name": "python3"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.8.2"
  },
  "widgets": {
   "application/vnd.jupyter.widget-state+json": {
    "state": {},
    "version_major": 2,
    "version_minor": 0
   }
  }
 },
 "nbformat": 4,
 "nbformat_minor": 4
}