Waves in the solar photosphere
  The solar photosphere is a partially ionized medium with collisions between electrons, various metallic ions and neutral hydrogen playing an important role in the momentum and energy transport in the medium. Furthermore, the number of neutral hydrogen atom could be as large as $10^{4}$ times the number of plasma particles in the lower photosphere. The non-ideal MHD effects, namely Ohm, Ambipolar and Hall diffusion can play an important role in the photosphere. We demonstrate that Hall is an important non-ideal MHD effect in the solar photosphere and show that Hall effect can significantly affect the excitation and propagation of the waves in the medium. We also demonstrate that the non-ideal Hall dominated inhomogeneous medium can become parametrically unstable, and it could have important ramification for the photosphere and chromosphere of the sun. The analysis hints at the possibility of solar photosphere becoming parametrically unstable against the linear fluctuations. 
B. P. Pandey, J. Vranjes and V. Krishan