The fast and slow solar wind show different kinetic and compositional properties at 0.3-1AU - the region where in-situ observations are available so far. Remote sensing spectroscopic observations in coronal streamers and holes in the inner corona further demonstrate the differences between the two types of the solar wind. The slow solar wind appears to originate from the boundaries of predominantly closed field regions, such as streamers, while the fast wind is accelerated in coronal holes. Even though the exact acceleration mechanism of the solar wind is not fully understood - observations strongly suggest that the fast and slow solar winds are accelerated by predominantly different processes. Models show that kinetic and MHD waves play an important role in the heating and acceleration of the fast solar wind, where the low frequency waves are important in the acceleration of protons and resonant waves lead to heavy ion heating. This is supported by observations of the anisotropies and other non-Maxwellian features in the proton and ion velocity distributions. MHD turbulence appears to play an important role in the cascade of energy and heating of the fast solar wind, although important issues are not resolved. The magnetic fluctuations power laws often exhibit three typical scalings determined by the driving source, the turbulence, and the dissipation processes.The slow solar wind heating and acceleration is more gradual, and the turbulence power law scaling is more complex than in the fast wind. I will discuss resent observations and models of the solar wind acceleration and heating, and the expected observations from the Solar Orbiter mission that will likely improve our understanding of these processes.

We present a study of coronal streamers observed during the last two solar minima (1996-2008) by the Ultraviolet Coronagraph Spectrometer (UVCS) onboard SOHO, accounting for the coronal magnetic topology, extrapolated by a 3D magneto-hydrodynamic model. The results of the analysis show several differences in the physical parameters between the 1996 and 2008 observations. In particular, for the last solar minimum, we found higher kinetic temperature and lower electron density values in the expanding regions and a peculiar scenario characterized by two regimes of slow wind outflow velocity values. The observations of the Multi Element Telescope for Imaging and Spectroscopy (METIS) on board Solar Orbiter performed during quasi-corotation and out-of-ecliptic, will give new perspectives to the study of the slow wind sources and of the role of the coronal magnetic field topology in controlling the solar wind dynamics and abundance, separating between radial, longitudinal and temporal scales of small-scale structures.

Although the morphology of the Helium component of the solar corona can place significant constraints on theories of the acceleration of the solar wind, measurements of this morphology are extremely limited. This situation will be addressed with the Helium channel of the Solar Orbiter METIS instrument. Some indications of the structure of the Helium corona have been obtained from SpaceLab2 CHASE, SOHO UVCS, CDS & EIT and SECCHI EUVI. However, these do not have the spatial coverage needed to address the solar wind problem. The 2009 flight of the HERSCHEL Sounding Rocket obtained measurements of the Helium abundance from the limb to 2.5 solar radii. This is exactly the region in which this measurement is critical to distinguish between solar wind processes. The HERSCHEL sounding rocket measurements will be presented in the context of the anticipated METIS observations.

We present a few spectral diagnostics available within the SPICE spectrometer to measure electron temperatures, chemical abundances, and Doppler motions. We discuss a few science cases where we explore the possibility to link these remote-sensing observations with the local in-situ measurements of the solar wind plasma parameters. In particular, we discuss the solar wind source regions in coronal holes and active regions.

The Heavy Ion Sensor (HIS) on SO, with its high time resolution, will enable us to examine the origin, structure and evolution of the solar wind in greater detail than ever before. During the co-rotation phase, we will be able to map solar wind structures back to the Sun in a way that has not yet been possible. HIS will enable characterization of the sources, transport mechanisms and acceleration processes of the solar wind as well as solar energetic particles through the measurements of the suprathermal seed population. Additionally, HIS measurements will constrain CME initiation mechanisms and the impact CMEs have on the evolution of coronal and heliospheric magnetic field over the mission lifetime. This presentation will focus on the current state of in-situ studies of heavy ions in the solar wind and their implications for the sources of the solar wind, the nature of structures and the variability of the solar wind, the impact of CMEs in the heliosphere, and the acceleration of particles. Additionally, we will also discuss opportunities for coordinated measurements across the payload and how, when combined, we will answer key outstanding science questions of central focus to the Solar and Heliophysics communities.

Solar wind plasma is far from thermal equilibrium and particle distributions that are measured in situ at different heliocentric distances often show significant deviations from Maxwellians. Several kinetic processes are at work during the solar wind expansion and contribute to the observed non adiabatic evolution of the plasma. In this talk I will review some of the main mechanisms that are believed to play a role in the shaping of particle distribution functions at various distances from the Sun, including wave-particle and wave-wave interactions, plasma instabilities, and Coulomb collisions. In particular, observational signatures of kinetic instabilities that regulate the evolution of the ion temperature anisotropy and differential drifts will be presented. The role of these kinetic processes in the plasma energetics, as well as their influence on the local properties of turbulence and coherent structures, are also considered. Relevant implications of solar wind kinetics on the observations and challenges of future space mission as Solar Orbiter and Solar Probe Plus will be discussed.

PROBA2/SWAP is an EUV telescope that monitors the solar corona at 17.4 nm. SWAP's 54'x54' field-of-view provides a unique view of large, EUV-emitting, coronal structures with heights up to approximately 2 solar radii. The aim of the present work is to analyse the evolution of the extended corona on long timescales. For that purpose, we generate high-quality, deep-exposure SWAP images by stacking many individual images obtained at relatively high cadence. The largest coronal structures appear mainly above or at the edges of active regions and are relatively dynamic, but the images also show many large-structures near the poles that persist for multiple Carrington rotations. Here we present an analysis of the extent, persistence, and three-dimensional structure of extended structures since the beginning of the PROBA2 mission in 2010.

In-situ observations at 1 AU have shown that the slow solar wind contains non-turbulent periodic density structures that are capable of driving magnetospheric oscillations. The alpha density is often anti-correlated with the proton density, suggesting a coronal origin for these structures. Indeed, we have recently detected such periodic (~100 min) small-scale density structures in heliospheric images of the slow solar wind (Viall et al 2010) taken at heliocentric distances above 15 R_sun.

Here, we extend this work to inner coronal heights (2.5 - 15 R_sun) using imaging observations from the SECCHI COR2 coronagraphs. We verify that 80-100 min periodicities are present at these heights. The periodic structures propagate along streamer stalks. To constrain the origin of these structures, we use PFSS extrapolations and COR1 images. There is some evidence that they emanate from the edges rather than the cusp of the streamer when those structures are visible in COR2. We find a small change in periodicity with increasing height, which is suggestive of acceleration.

Reference: Viall, N. M et al. 2010, Sol. Phys., 267, 175