Investigation of Particle-Energization in Plasmas Through Wave-Particle Correlation Measurements

About This Grant

This award supports an experimental study of space-like plasmas in a laboratory setting. Space plasma phenomena impact human infrastructure in space, such as satellites and manned space vehicles, and technological systems on Earth, such as power grids, global positioning systems (GPS), and long-distance radio communication. One of the challenges in understanding naturally occurring phenomena in outer space is the difficulty and the expense of performing scientific measurements in space. Another challenge is that nature rarely produces the exact same event multiple times to allow for distinguishing random measurement fluctuations from the phenomena of interest. Yet, the characteristics of the plasma in the space environment are key to understanding and predicting such space plasma phenomena. This project will study how energy is transferred from waves to particles in space-like plasmas contained in the PHASMA facility at West Virginia University. The broader impacts of the project include training of graduate students in a research environment that emphasizes the synergy between basic and applied plasma physics; recruiting and retaining undergraduates into physics through involvement in cutting-edge research activities; and support of an educational initiative that provides hands-on STEM activities to K-12 students. The in-situ measurement of ion and electron velocity distribution functions in space has revolutionized the field of space physics by providing the space physics community the ability to study and understand kinetic-scale plasma processes; test theories and computational models; and to discover new plasma phenomena. The PHASMA facility has the capability to non-perturbatively measure the three-dimensional (3D) ion and electron velocity distribution functions (VDFs), magnetic fields, and turbulence in laboratory plasmas created at space-relevant conditions. This project addresses three open scientific questions in plasma physics and supports the development of a new diagnostic method, quantum beat spectroscopy (QBS), for measuring weak magnetic and electric fields in plasmas. The first study focuses on particle energization during magnetic reconnection by exploring the correlation between perturbations to the 3D electron velocity distribution function (EVDF) and spontaneously appearing electrostatic lower hybrid drift waves. The second study involves measurements of EVDF perturbations when the waves are externally driven rather than spontaneously excited by local instabilities, as in the edge of a helicon plasma source. A third study will explore the effects of flow shear on the rate of reconnection and the effects of changing the guide field strength on the direction of propagation of the reconnection site between two tilted merging flux ropes. All three of these studies will be compared to numerical and theoretical predictions. The QBS development effort will provide an exciting new method of non-perturbatively measuring weak magnetic and electric fields in low-pressure laboratory plasmas. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.