1. Meeting on Solar Wind Turbulence, Kennebunkport, June 4-7, 2013
Sharp Boundaries of Small-Scale and Middle-Scale Solar Wind Structures and possible role of electrostatic potential in it’s formation.
M. Riazantseva1,2, G. Zastenker1, I. Aleshin 3, O. Trubachev 4
1- Space Research Institute, Russian Academy of Sciences
2- Skobeltsyn Institute of Nuclear Physics of Moscow State University
3- Schmidt Joint Institute of Physics of the Earth, Russian Academy of Sciences
4- Physic faculty of Moscow State University
Contact person: Maria Riazantseva

2. Ion flux jump with absence of pressure balance on front.
The sharp (with front duration of several seconds) ion flux changes are observed often in the solar wind plasma (not due to shocks). These changes are boundaries of small- and middle-scale solar wind plasma structures and are the part of solar wind turbulence.
The total pressure is not in balance in more than 10% of the events (changing of the pressure is more than 30% ). When pressure is not in balance, the events should evolve. However they don’t change during long time periods in many cases.
Riazantseva M.O., Zastenker G.N., Richardson J.D., P.E. Eiges Sharp boundaries of the solar wind small-scale and middle-scale structures. J. Geophys. Res., V.110, A12110, doi: /2005JA
An example of a jump of the solar wind ion flux. Bulk velocity, proton temperature and magnetic field value and direction stay stable.

3. Model of formation of density jump in isotropic plasma
Spatial variations of the plasma pressure can be associated with the existence of an electrostatic potential barrier, so-called double layer. The imbalance of the total pressure is explained by the existence of regions in which the quasineutrality of plasma is violated.
Model gives the possibility to estimate the maximum density jump if plasma parameters are known. The good quality electric field measurements are needed for proofing of this hypothesis .
A comparison of the model with observations. Points represent events with sufficiently large imbalance of pressure: dP/P > 30% (β > 1, Te > Ti). The solid curve presents the maximum value of a density jump at a given temperature ratio of the components.
Aleshin I. M. , Zastenker , G. N. , Riazantseva M.O., Trubachev O.O., Possible Role of Electrostatic Potential in Formation of Sharp Boundaries of Small-Scale and Middle-Scale Solar Wind Structures, Cosmic Research, 2007, Vol. 45, No. 3, pp. 181–185.