Ajeeta Khatiwada
Colorado Research Associates
Mentor: Dr. Ashley Crouch

 

Title: Evaluating Magnetic Fields for the Helical Kink Instability

 

Abstract:
The initiation mechanism for solar energetic events is not well understood. However, Helical Kink Instability of a twisted flux tube has been proposed as one of the possible mechanisms for triggering such events. Measuring the amount of magnetic helicity or calculating the number of times magnetic field lines wind around the axis of a flux tube may enable one to predict the Kink Instability. On the basis of previous researches, a pre-existing Genetic Algorithm optimization code is modified in order to fit the model field to the observation data. The best set of parameters is then determined and the result is interpreted in the context of Kink Instability. Initially, the code is tested on simulated twisted flux tubes and is finally applied to NOAA AR 7201 observed on 06/19/1992 with the NSO/HAO Advanced Stokes Polarimeter. The value of the total twist obtained from fitting the observation to a model suggests that the flux tube is susceptible to Kink instability and the center of the torus (the circular structure of the flux tube as proposed by one of the models) is emerged out of the solar interior. Fitting the observation with different models and comparing the results suggests that better ways and more appropriate models may be required to determine the twist parameter of the flux tube.