DISCRETE RANDOM HEATING EVENTS IN CORONAL LOOPS

The response of the coronal plasma in a magnetic loop to the release o f discrete, random amounts of energy quanta over fixed time intervals is investigated. Nanoflare heating (10(24) erg per event) with event l ifetimes on a scale of 1-20 s are shown to be able to maintain a coron al loop at typical coronal temperatures, approximate to 2 x 10(6) K (P arker, 1988; Kopp and Poletto, 1993). Microflare events (10(27) erg) o bserved by Porter et al. (1995) with a lifetime of approximately 1 min are also investigated and it is found that the loop apex temperature varies by at most 40% from its initial static condition. However, larg er energy events of the order of 10(28) erg (Schmieder et al., 1994) o ccur too infrequently and the plasma cools to chromospheric values. Th e implications of time-dependent heating of the corona upon observatio ns are also discussed.