ON THE QUALITY OF RESONANT ABSORPTION AS A CORONAL LOOP HEATING MECHANISM

The quality Q of a resonance is defined as the ratio of the total ener gy contained in the system to the dissipation per driving cycle. Hence , a 'good quality' resonance is one with little losses, i.e., little d issipation per driving cycle. However, for heating coronal plasmas by means of resonant absorption of waves, 'bad' quality resonances are re quired. Here, the quality of the MHD resonances that occur when an inh omogeneous coronal loop is excited by incident waves is investigated f or typical coronal loop parameter values in the frame work of linear, resistive MHD. It is shown that the resonances in coronal loops have b ad quality and, hence, yield a lot of Ohmic heating per driving cycle compared to the total energy stored in the loop. As a consequence, the time scales of the heating process are relatively short and resonant absorption turns out to be a viable candidate for the heating of the m agnetic loops observed in the solar corona.