Neoclassical bootstrap current in solar plasma loops

Abstract

From the similarities in magnetic configurations and plasma behaviors between tokamaks and solar current-carrying plasma loops, we apply the theory of neoclassical bootstrap current in tokamaks to the solar plasma loops. We present a simplified expression of the bootstrap current in the solar plasma loops and find that there may be a considerable component of the neoclassical bootstrap current in some compact current-carrying solar flare loops; e.g. the fraction of the bootstrap current is up to 44.6% of a flare loop of the event that occurred on Aug. 25, 1999. We suggest that the neoclassical effect changes the current distribution and affects the instability of solar plasma loops. Based on the data analysis of SXT/Yohkoh, HXT/Yohkoh, GOES, and NoRP, we find that the timescale of the neoclassical tearing modes is consistent with the rising time of the impulsive phase during the event, while the timescale of the classical tearing modes is much longer than that of the event, which may provide important evidence of the bootstrap current and help us understand the mechanisms of the eruptive events, such as solar flares, prominence, and CMEs.