doc/coupling_to_plasma_from_COMSOL.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Plasma Coupling Using COMSOL Results"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "In this example, we use a COMSOL front-face coupling calculation provided by ORNL, exported as a standard Touchstone file.\n",
    "\n",
    "The Touchstone file is first import as a scikit-rf Network, which is then modified to fit the WEST ICRH antenna electrical model requirements."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 25,
   "metadata": {},
   "outputs": [],
   "source": [
    "import numpy as np\n",
    "import skrf as rf\n",
    "\n",
    "# WEST ICRH Antenna package\n",
    "import sys; sys.path.append('..')\n",
    "from west_ic_antenna import WestIcrhAntenna"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 26,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "4-Port Network: 'ORNL_front_face_conventional',  55000000.0-55000000.0 Hz, 1 pts, z0=[50.+0.j 50.+0.j 50.+0.j 50.+0.j]\n"
     ]
    }
   ],
   "source": [
    "front_face_conventional = rf.Network(\n",
    "    '../west_ic_antenna/data/Sparameters/front_faces/COMSOL/ORNL_front_face_conventional.s4p')\n",
    "print(front_face_conventional)  # 50 Ohm S-param component at a single frequency of 55 MHz"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The ports have been defined as:\n",
    "<img src=\"COMSOL_WEST_port_index.png\" />\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "So before to use the S-parameters directly to feed the electrical model, we need to:\n",
    "- deembed the ports by 0.3m.\n",
    "- renomalize port reference impedance to the front-face coax characteristic impedances. \n",
    "- reverse ports 2 and 3."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 27,
   "metadata": {},
   "outputs": [],
   "source": [
    "# creating a 50 Ohm dummy coax line to be removed from the front face \n",
    "media_coax = rf.DefinedGammaZ0(frequency=front_face_conventional.frequency) # 50 Ohm TEM media\n",
    "extra_line = media_coax.line(d=0.3, unit='m')\n",
    "# deembedding all the 4 pourts\n",
    "for port_idx in range(4):\n",
    "    front_face_conventional = rf.connect(front_face_conventional, port_idx, extra_line.inv, 0)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We expect the port to have a characteristic impedance of about 46.64 ohm, so we renormalize the Network to fit this need:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 28,
   "metadata": {},
   "outputs": [],
   "source": [
    "front_face_conventional.renormalize(46.64)  # done inplace"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "And finally, for historical reasons (may change in a near future ;), the S-matrix port ordering should be ajusted:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 29,
   "metadata": {},
   "outputs": [],
   "source": [
    "front_face_conventional.renumber([1, 2], [2, 1]) # done inplace"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "OK, so now we can create the WEST antenna object:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 30,
   "metadata": {},
   "outputs": [],
   "source": [
    "ant = WestIcrhAntenna(front_face=front_face_conventional,\n",
    "                     frequency=front_face_conventional.frequency) # restrict to single frequ"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Let's match the antenna for this coupling:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 31,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Looking for individual solutions separately for 1st guess...\n",
      "Wrong solution (out of range capacitor) ! Re-doing...\n",
      "False solution #1: [150. 150.]\n",
      "True solution #1: [52.57986227 45.88696785]\n",
      "True solution #1: [52.30894839 46.0700872 ]\n",
      "Searching for the active match point solution...\n",
      "Reducing search range to +/- 5pF around individual solutions\n",
      "True solution #1: [53.67807308 46.12207788 53.62800637 46.30935881]\n"
     ]
    }
   ],
   "source": [
    "Cs = ant.match_both_sides(f_match=55e6)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The coupling resistance of the antenna for this coupling in a nominal dipole excitation is:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 32,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([0.70081638, 0.6878438 ])"
      ]
     },
     "execution_count": 32,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "power = [1, 1]\n",
    "phase = [0, np.pi]\n",
    "\n",
    "# Coupling resistance\n",
    "ant.Rc(power, phase)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The voltage and currents are:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 44,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([[22.16126386, 23.75535708, 20.56902439, 25.21223565]])"
      ]
     },
     "execution_count": 44,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "power = [1, 1]  # MW, to adjust to fit with experiment\n",
    "phase = [0, np.pi]  # rad\n",
    "\n",
    "abs(ant.voltages(power, phase))  # results in kV"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 41,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([[0.70248687, 0.75556107, 0.65298786, 0.80405425]])"
      ]
     },
     "execution_count": 41,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "abs(ant.currents(power, phase))  # results in kA"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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