Abstract | Many aspects of the origin, acceleration and anisotropy of solar wind particles are poorly understood
till date. These particles can arrive at the first Lagrangian point (L1) of the Sun-Earth system from a
number of directions. Further, thermal anisotropy of the solar wind particles along and across the
Parker spiral direction is also known. Therefore, in order to understand the solar and interplanetary
processes based on solar wind measurements, it is essential to have multi-directional measurements
of both low and high energetic particles. In addition, it is also important to measure He2+ (second
most abundant ions) and H+
(most abundant ions) ions separately as their differential behavior may
throw light on the physical processes associated with the origin, acceleration and anisotropy of solar
wind. Keeping these aspects in mind, Aditya Solar wind & Particle EXperiment (ASPEX)
experiment on Aditya-L1 mission has been designed. ASPEX will make in-situ, multi-directional
measurements of the slow & fast solar wind, supra-thermal and energetic particles in the energy
range of 100 eV to 5MeV /n using its two sub-systems - Solar Wind & Ion Spectrometer (SWIS)
and the Supra Thermal & Energetic Particle Spectrometer (STEPS). |