Faculty & Staff

Specific interests: All aspects of suprathermal (energetic) charged particle transport and acceleration in the solar wind plasma. Particle populations of interest include solar energetic particles, pickup ions, anomalous cosmic rays and galactic cosmic rays, Test particle and self-consistent finite difference and finite volume simulations of suprathermal charged particle transport and acceleration in the solar wind plasma, The acceleration of solar energetic particles at fast coronal mass ejection driven traveling bow shocks, including self-consistent wave generation, The acceleration of interstellar pickup ions at the heliospheric termination shock, including modification of the shock structure by the accelerated pickup ions (see figure), The acceleration of superthermal particles in a "sea" of contracting and merging (reconnecting) small-scale magnetic flux ropes in the supersonic solar wind plasma and in the corona, The non-diffusive parallel and perpendicular transport of energetic charged particles in intermittent low-frequency solar wind magnetic field turbulence including propagation of anomalous and galactic cosmic rays through the heliopause.

Comparison of Voyager 2 energetic ion spectral data behind the heliospheric termination shock as adapted from Decker et al., 2008 (left panel) with a kinetic focused transport theory simulation (right panel) of the shock accelerated interstellar pickup proton spectrum (left panel). The simulation illustrates the importance of including perpendicular diffusion of accelerated pickup ions across the termination shock due to magnetic field-line random walk in the shock acceleration process. The work was published in Astrophysical Journal Letters in 2013 with current Ph.D. student Aaron Arthur as the lead author.

• B.Sc. Physics and Mathematics, University of Stellenbosch, Stellenbosch, South Africa 1982

• Title: Probing the Physics of the Heliopause Sponsor & Grant No.: NASA NNX14AF43G Total Award Amount: $395,000
• Title: Energetic Charged Particles in the Heliosphere: Are Observations Consistent with Acceleration by Shocks? Sponsor: NASA Washington, D.C., HQ Total Award Amount: $1,059,173.00
• Title: Anomalous Diffusion in the Collisionless Solar wind Plasma Sponsor & Grant No.:: NSF-DOE/ARRA ATM-0904007 Total Award Amount: $438,228
• Title: Modeling the radial dependence of the shock acceleration of solar energetic particles from the corona to Earth with a time-dependent focused transport model Sponsor & Grant No.: NASA NNX09AJ79G Total award amount: $439,902
• Title: Global modeling of the ENA fluxes in the heliosphere: IBEX Guest Investigators program Sponsor: NASA Headquarters Amount: $419,799 over 3 years ($10,538 salary + benefits for Co-I le Roux)
• Proposal Title: The microphysics of the heliospheric termination shock Sponsor: NASA Washington, D.C., HQ Total Award Amount: $433,097 ($38,354 salary + benefits for Co-I le Roux)
• Title: The Physics of the Inner Heliosheath: Implications for Cosmic Rays Sponsor: NASA Headquarters Amount: $415,622 over 3 years

• ZHAO, L. L., ZANK, G. P., CHEN, Y., HU, Q., LE ROUX, J. A., DU, S. & ADHIKARI, L. 2019. Particle Acceleration at 5 au Associated with Turbulence and Small-scale Magnetic Flux Ropes. Astrophysical Journal, 872:4. 16 pp.

• STRAUSS, R. D. & LE ROUX, J. A. 2019. Solar Energetic Particle Propagation in Wave Turbulence and the Possibility of Wave Generation. Astrophysical Journal, 872:125. 15 pp.

• PRINSLOO, P. L., STRAUSS, R. D., & LE ROUX, J. A. 2019. Acceleration of Solar Wind Particles by Traveling Interplanetary Shocks. The Astrophysical Journal, 878:144. 22 pp.

• ZHAO, L.-L., ZANK, G. P., HU, Q., CHEN, Y., ADHIKARI, L., LE ROUX, J. A., ... BURLAGA, L. F. 2019. ACR Proton Acceleration Associated with Reconnection Processes beyond the Heliospheric Termination Shock. The Astrophysical Journal, 886:144. 11 pp.

• WEBB, G. M., AL-NUSSIRAT, S., MOSTAFAVI, P., BARGHOUTY, A. F., LI, G., LE ROUX, J. A., & ZANK, G. P. 2019. Particle Acceleration by Cosmic Ray Viscosity in Radio-jet Shear Flows. The Astrophysical Journal, 881:123. 25 pp.

• LE ROUX, J. A., WEBB, G. M., KHABAROVA, O. V., ZHAO, L. L., & ADHIKARI, L. 2019. Modeling Energetic Particle Acceleration and Transport in a Solar Wind Region with Contracting and Reconnecting Small-scale Flux Ropes at Earth Orbit. The Astrophysical Journal, 887:77. 25 pp.

• le Roux, J. A., Webb, G. M., Khabarova, O. V., Zhao, L. L., & Adhikari, L., Modeling Energetic Particle Acceleration and Transport in a Solar Wind Region with Contracting and Reconnecting Small-scale Flux Ropes at Earth Orbit, The Astrophysical Journal, 887, 77, 2019. 25 pp.