Lev D. Landau and Lyman Spitzer Jr. Award for Outstanding Contributions to Plasma Physics: Unraveling the Physics of Particle Energization in Space and Astrophysical Plasmas: The Field-Particle Correlation Technique

Under the weakly collisional conditions typical of space and astrophysical plasmas, fundamental plasma processes such as kinetic plasma turbulence, collisionless magnetic reconnection, collisionless shocks, and kinetic instabilities govern the transport of energy across scales and the consequent energization of the plasma, through either the heating of the plasma species or the acceleration of a small fraction of particles to high energy. Many of these energization mechanisms remain poorly understood, but kinetic simulations and spacecraft observations present valuable opportunities to improve our understanding of the fundamental kinetic physics. The field-particle correlation technique was devised to combine measurements of the particle velocity distribution functions and electromagnetic fields at a single point in space to generate a characteristic velocity-space signature that can be used to identify the kinetic mechanism of particle energization and quantify the energization rate. In this talk, the kinetic plasma theory underlying the field-particle correlation technique will be reviewed. The technique has been successfully applied to identify different physical mechanisms involved in the dissipation of kinetic plasma turbulence, the acceleration of particles at collisionless shocks, and the heating of electrons in collisionless magnetic reconnection. The unique velocity-space signatures of these different processes can be compiled to generate a "Rosetta stone" for the definitive identification of different particle energization mechanisms in space and astrophysical plasmas. Application of the technique to large statistical samples of spacecraft data holds the promise to create predictive models of energy transport and plasma heating in turbulence, reconnection, shocks, and instabilities as a function of the plasma and system parameters

Publications Reference:

1. Afshari, A. S., Howes, G. G., Kletzing, C. A., Hartley, D. P., and Boardsen, S. A., J. Geophys. Res., 126, e2021JA029578 (2021).

*2. Chen, C. H. K., Klein, K. G., and Howes, G. G., Nat. Comm., 10, 740 (2019).

3. Klein, K. G., Howes, G. G., and TenBarge, J. M., J. Plasma Phys., 83 , 535830401 (2017).

4. Howes, G. G., Klein, K. G., and Li, T. C., J. Plasma Phys., 83 , 705830102 (2017).

5. Klein, K. G. and Howes, G. G., Astrophys. J. Lett., 826, L30 (2016).