The primary goal of the project is to analyze the interactions between plasmas and neutral particles by developing a three-fluid model. The three fluids are free electrons, the ions and the neutrals. The coupling comes via collisions among the different species and the electromagnetic field that connects different regions of interest. The purpose of the analysis is to provide a more physical and analytical understanding of the coupling. Rather than starting with complicated equations and a realistic geometry the approach here will be to conduct as much analytical analyses as possible. Additional terms and equations and more realistic geometries will be gradually introduced when the simpler ones are understood.
The results of the theoretical analysis will be applied to the coupling between the magnetosphere, the ionosphere and the thermosphere, but the theoretical analysis could potentially be applied to many areas of space and astrophysical plasma phenomena. In particular the work has the potential to give new insight into the problem of chromospheric/coronal heating. Much of the research will be carried out by a graduate student.
Normal 0 false false false EN-US ZH-CN X-NONE Since the discovery of the solar atmosphere, known as the solar corona, being extremely hot, 2 million degrees, the solar coronal heating has been an outstanding science problem in solar physics and astrophysics. As we know that the temperature at the surface of the Sun, known as the photosphere, is only 6000 degrees, if the solar atmosphere is heated by the heat from the surface of the Sun, how can a heater of 6000 degrees heat its surroundings to 2 million degrees? This impossibility is known as the second law of thermal dynamics which states a simple fact that heat flows from higher temperature regions to lower ones, and not vice versa. What made this problem worse is by another observation which shows that a large amount of energy actually radiates from the lower part of the solar atmosphere, a region known as the chromosphere; i.e., the energy from the Sun not only has to heat the corona but also has to provide the energy for chromospheric radiation. Quantitatively, the energy loss in radiation is a factor of 100 bigger than needed to heat the atmosphere to 2 million degrees! People have realized that the Sun is very turbulent and the energy associated with the turbulence, similar to many atomic bombs going off everywhere on the Sun, can provide the required energy. However, the question is how the motional energy can be converted to the thermal energy. Previous theories are able to produce about few percent of the required energy based on the observed turbulence energy. Professor Paul Song and Distinguished Research Professor Vytenis Vasyliunas of Physics Department and Center for Atmospheric Research of UMASS Lowell recently proposed a new theory that may lead to final resolution of coronal heating problem. They analyzed perturbation propagation from the solar surface to the coronal through the chromosphere, a difficult mathematical-physical problem. They found that the perturbations are heavily damped and the motional energy of perturbation can be converted to heat in regions where the magnetic field is weaker. The damping and the heating is weaker in stronger field regions. Conventional wisdom has been focusing on regions of stronger magnetic field because these are where stronger perturbations are observed. Now everything becomes clear: stronger perturbations are observed in stronger field regions because they are not damped, and vice versa. This theory is able to convert the observed level of the turbulence energy to required thermal energy. They are continuing working on the consequences of the heating mechanism to explain other observed phenomena. Professors Song and Vasyliunas also recognized the similarity between the solar chromosphere and the Earth’s ionosphere/thermosphere system: both are highly-collisional weakly ionized magnetized fluids. In the earth’s magnetosphere-ionosphere/thermosphere coupling, the motional energy input from the magnetosphere, instead of from the bottom like on the sun, and dissipates in the ionosphere/thermosphere which produces many space weather phenomena and effects. The knowledge we gained in understanding of the weakly ionized magnetized fluid from the solar coronal heating can be applied to understanding the processes in the ionosphere.
