The physics responsible for the origin and evolution of the solar wind remains an open question. Existing theories rely on magnetic reconnection and/or non-linear alfv n wave phenomena. The solar…

This federal contract award, valued at $358,099.00, was issued by the National Aeronautics and Space Administration (NASA) to the Space Science Institute (SSI), a nonprofit research organization based in Boulder, Colorado. The award supports research to improve understanding of the physical processes responsible for the origin and evolution of the solar wind, in preparation for NASA's upcoming Solar Probe Plus mission. The research will involve laboratory experiments at the University of California, Los Angeles to study shear Alfvén wave parametric instabilities, which may play a key role in solar wind heating and acceleration. The findings are expected to help interpret data from the Solar Probe Plus mission, which aims to make unprecedented in-situ measurements of the near-Sun solar environment. This award does not include a set-aside designation, as SSI competes for contracts based on scientific and technical merit. The organization has extensive experience supporting NASA, the National Science Foundation, and the Department of Energy through both prime and subcontract awards in areas such as astrophysics, planetary science, and heliophysics.

The physics responsible for the origin and evolution of the solar wind remains an open question. Existing theories rely on magnetic reconnection and/or non-linear alfv n wave phenomena. The solar probe plus mission to be launched in 2018 will pass within 8.5 solar radii of the sun, providing new in-situ measurements. In preparation for these new observations, IT is important to develop a clear idea of signatures that may indicate the presence of various physical processes that may be responsible for the heating and acceleration of the solar wind. Shear alfv n wave parametric instabilities, in which an unstable large amplitude alfv n wave non-linearly produces other modes, may be particularly important in the region solar probe plus is expected to study. For instance, the ION acoustic mode produced from parametric delay of a large amplitude alfv n wave could directly heat ions; thus, this process could help account for unexplained coronal heating. Parametric decay also produces a backward propagating alfv n wave and thus may help explain why waves propagating in both directions are observed in the solar wind. Parametric instabilities may also serve as an intermediate instability mechanism for the transfer of energy from large to small spacial scales. While there has been an abundance of theoretical work on shear alfv n wave parametric instabilities, observational evidence is extremely limited. Basic laboratory experiments may play a key role towards validating theoretical models and providing predictions for solar probe plus observations. Central question: what role do shear alfv n wave parametric instabilities play in the origin and evolution of the solar wind? Science questions: 1. Under what sets of plasma parameters are shear alfv n wave parametric instabilities observed in the lab? How do these parameters compare to what is expected to be observed by solar probe plus? 2. How do key features of the instability vary with important parameters such as plasma beta and pump wave frequency? How do these features compare to theoretical predictions? 3. Which instability signatures observed in the lab may used to inform future space observations such as solar probe plus? Methodology: experiments will be conducted at the large plasma device (lapd) at ucla, which can produce a 20M long, 60CM diameter plasma column that is ideal for wave studies. The lapd is equipped with an extensive set of diagnostics and a computer-controlled data acquisition system. Antenna and driver circuits for launching the waves are also available at the facility. The values of various dimensionless parameters (e.g. plasma beta or the ratio between plasma and electron cyclotron frequencies) can span a range of values relevant to the near-sun solar wind and corona. Relevance: the proposed research is directly relevant to the three heliophysics science goals in the 2014 NASA science plan and to the upcoming solar probe plus mission. Specifically: goal 1) parametric instabilities represent an important physical process at work in the space environmental. The process may be particularly important close to the sun, where solar probe plus aims to understand how the sun's corona is heated and how the solar wind is accelerated. Parametric instabilities may have a direct impact on coronal heating and the evolution of the solar wind, thus the proposed research is particularly timely and relevant. In particular, the list of observational signatures to be developed will greatly aid the interpretation of future mission data. Goals 2 and 3) the solar wind is an important link between different regions of our heliopshere. The improved understanding of the corona and near-earth solar wind gained from the proposed research will advance our understanding of the connections that link the sun to other regions of our solar system. This improved understanding is also crucial to future predictions of space weather events.