Plasma diagnostics and the heating of the solar corona

• Main Author: Daniel, R. D.
• Published: University of Cambridge 2006
• Subjects: 520
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598268

Firstly, we present reviews of the background atomic, magnetohydrodynamic, and solar, physics involved in the analysis of the problem. We proceed to produce a time dependent code to calculate the Ionisation state distribution of Iron and of Argon, using some of the recent data for Ionisation coefficients by Arnaud & Raymond (1992), and Fournier et al. (1997, 1998). We also look at some data for the excited ionised states using the Chianti database amongst others. Taking the engine developed, we continue by applying it to a three stage nanoflare simulation for the heating, spanning a 2000km range. This model is drawn from various previous models developed in the literature. We look for the indications of the non Local Thermodynamic Equilibrium (LTE) processes via the concept of "signature ions". By this we mean the presence of highly charged ions which would not be expected if the temperature were simply constant and everywhere was in LTE. We make a calculation of the actual experimental line of sight results that we would obtain, if we were to take Emission Measure calculations to ascertain the Ionisation distribution within the Solar Atmosphere. We also take a look at the problem of Diagnostics based on Emission Measure Analysis, and investigate the fundamental nature of the Inversion Problem. Simply stated, it is difficult to obtain the differential emission measure (DEM) of the Transition Region because the only information that we have available to us is the intensity of spectral lines emitted from the Sun. This consists of the integral of the DEM convolved with a function representing the physics of the transition. The problems associated with the inversion of the integral, form much of the discussion together with the philosophical implications of using phenomenology as an alternative.