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Matt ThorntonMPhys Mathematics and Theoretical Physics, University of St Andrews 2016REU Student - Summer 2015 Contact: matthew.charles.thornton [at] physics.org Office: EPS 230 Supervisor: Dana Longcope |
Research projectSolar flares are among the most energetic events on the sun. Through magnetic reconnection, magnetic energy is released as kinetic energy and thermal energy, accelerating the coronal plasma to high speeds. This hot and fast plasma can release radio waves, x rays, and EUV light which can be detected. In my project I computationally solve the dynamical equations governing a magnetic flux tube after reconnection has occurred, and study how the initial conditions of the magnetic field affect the density and temperature of the plasma. Throughout the summer I have also attended lectures and seminars hosted by MSU on various aspects of solar physics, space science, instrumentation and optics.Here's what I've been up to each week: week 1 - introduced to PREFT, the program I'll be working in for the summer. I begin simulating flux tube retraction and observe shocks forming in the plasma. As a first wee project I write a program to track the motion of the shock front through space, and observe that it moves at the Alfven speed as expected. Also attended IDL tutorials. week 2 - I spent a decent amount of time becoming increasingly familiar with PREFT and IDL. Lots of time spent reading papers (some linked to below) and learning about flares from the Cambridge Encyclopedia of the Sun (Lang).week 3 - beginning to investigate energy released in the flare due to magnetic reconnection, and how it distributes itself. I observe that magnetic energy is converted into kinetic energy by the Lorentz force and then changed into thermal energy by the shocks - this confirms some of my background reading. Qualitative notes made on how peak flux tube temperature/pressure vary with time and with changing magnetic field strength. week 4 - spending most of the week collecting data. I want to know how the initial conditions of the flux tube (eg. its length, the angle at which it is bent, the magnetic field strength, the position of the bend) affect its subsequent evolution. Also building some of the machinery which will quantiatively analyse my data. week 5 - I am focusing mainly on the peak temperatures and peak pressures of the flux tube. I found that my simulations nicely matched theoretical considerations for how the peak temperature should vary with magnetic field strength, flux tube length, bend angle. Calculations only valid for a certain form of heat flux - will investigate this further soon. week 6 - time spent gathering missing points in data, and preparing for the midterm presentation. Made qualitative notes on how peak temperature varies for a different thermal conductivity (designed to limit the heat flux and keep it below a maximum physical value). week 7 - Delivered midterm presentation on Monday afternoon, and learned what the other REU students have been working on. Latter half of the week spent working on theoretical predictions of peak temperature for the modified thermal conduction. The data can be fitted by a basic power law, which fed further into my theoretical considerations. Possible equation to predict peak temperature derived and seems to fit the simulated data reasonably well. week 8 - Spent time refining my equations for the peak temperature and fitting them to data from simulations in IDL. Found good fits as I vary how the heat flux is limited. Plotting a graph of peak temperature against the heat flux limiting factor reveals the power law that my equation should have for this parameter. I'll go back and slightly alter my equation toward the end of this week and hopefully it will fit my simulation data much better week 9 - we all had a great weekend at the lake house belonging to one of the professors in physics, a couple hours North of Bozeman. Lots of time spent on the lake (rafting and swimming), sitting around the campfire, and sleeping under the stars. Research-wise, I'm spending part of this week refining my expression for the peak flare temperature. My predictions only seem to fit the simulations when the flux tube has an initial bend angle of ~90 degrees or less - it'd be nice to have an expression which works at higher bend angles. |
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Here is my midterm presentation Here is my final presentation Here is a link to a movie from the Solar Dynamics Observatory Here is some info on magnetic reconnection Here is some info on solar flares |