Solar phenomena move about and can travel at a few hundred meters per second when they first appear. The solar wind is a stream of plasma released from the Sun's upper atmosphere. It consists of mostly electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in density, temperature and speed over time and over solar longitude. These particles can escape the Sun's gravity because of their high energy. The solar wind is divided into the slow solar wind and the fast solar wind. The slow solar wind has a velocity of about , a temperature
Plasma diagnostics Some atoms are excited by collisions within the plasma and emit radiation. This can be used to probe density fluctuations in a turbulent plasma. In very hot plasmas (as in magnetic fusion experiments), light elements are fully ionized and don't emit line radiation. When a beam of neutral atoms is fired into the plasma, electrons from beam atoms are transferred to hot plasma ions, which form hydrogenic ions which promptly emit line radiation. This radiation is analyzed for ion density, temperature, and velocity. If the plasma is not fully ionized but contains ions that fluoresce, laser-induced fluorescence can provide very