3D MHD MODELING OF TWISTED CORONAL LOOPS

We perform MHD modeling of a single bright coronal loop to include the interaction with a non-uniform magnetic field. The field is stressed by random footpoint rotation in the central region and its energy is dissipated into heating by growing currents through anomalous magnetic diffusivity that switches on in the corona above a current density threshold. We model an entire single magnetic flux tube in the solar atmosphere extending from the high-beta chromosphere to the low-beta corona through the steep transition region. The magnetic field expands from the chromosphere to the corona. The maximum resolution is similar to 30 km. We obtain an overall evolution typical of loop models and realistic loop emission in the EUV and X-ray bands. The plasma confined in the flux tube is heated to active region temperatures (similar to 3 MK) after similar to 2/3 hr. Upflows from the chromosphere up to similar to 100 km s(-1) fill the core of the flux tube to densities above 10(9) cm(-3). More heating is released in the low corona than the high corona and is finely structured both in space and time.