{ "cells": [ { "attachments": {}, "cell_type": "markdown", "id": "4d53d061", "metadata": {}, "source": [ "# Updating Plasma and Convergence\n", "\n", "As light travels through a real plasma, it has effects on the properties of the plasma due to light-matter\n", "interactions as well as the presence of extra energy from the light. Additionally, as [previously discussed](../montecarlo/propagation.rst), properties of the plasma affect how light travels through it. This is a typical equilibrium problem. We solve for the plasma properties by finding a steady-state solution; that is, the actual plasma will be in a state such that the plasma state will not change as\n", "light propagates through it, because the effects of the light on the plasma and the effects of the plasma on the\n", "light are in equilibrium.\n", "\n", "One of TARDIS's main goals is to determine this plasma state (as we need the actual plasma properties in order to\n", "get an accurate spectrum). This is done in an iterative process. After each [Monte Carlo iteration](../montecarlo/index.rst) (which sends light through the supernova ejecta), TARDIS uses the [Monte Carlo estimators](../montecarlo/estimators.rst)\n", "how the propagating light affects the plasma state, after which the plasma state is updated (as will be explained below and demonstrated in the code example). We do this many times, and attempt to have the plasma state converge\n", "to the steady-state we are looking for. In fact, all but the last Monte Carlo iteration is used for this purpose\n", "(after which TARDIS will have the necessary plasma state for its last iteration which calculates the spectrum).\n", "\n", "