Dr. Epstein’s research interests include the simulation and interpretation of x-ray spectrum and image-based diagnostics of laser-driven implosions and the theory and simulation of radiation transport in implosion experiments, including the radiative properties of matter under nonequilibrium high-energy-density conditions. Examples include quantitative measurements of fuel–shell mix based on the spectral emission of tracer materials and measurements of implosion dynamics by self-emission and by soft x-ray radiography of imploding cryogenic hydrogen shells.
Dr. Epstein outreach activities include LLE’s annual Plasma Expo display at the APS/DPP meeting, and he has mentored 25 students in as many years in the LLE Summer High School Research Program. He was also selected as an Outstanding Referee for the journals of the American Physical Society.
Dr. Epstein’s research experience began in 1965 with summer work at UCLA as a lab helper for Lowell L. Wood who is known for creating the field of inertial confinement fusion with John Nuckolls and others in 1972. In graduate school, Dr. Epstein focused on the theory of gravitational radiation, creating, with Robert V. Wagner, a weak-field expansion formalism for sources of gravitational radiation. As a postdoctoral research associate at MIT, he and Irwin I. Shapiro published a second-order expression for the bending of light by the solar gravitational field, and, on his own, showed that measurements of second-order general relativistic effects in the first binary pulsar (PSR-1913+16), including gravitational radiation, were feasible and showed that neutrinos escaping from a supernova could be a significant source of gravitational radiation.
Impressed by the challenges in the field of inertial confinement fusion and its similarities with astrophysics, he joined the Laboratory for Laser Energetics in August 1979 where he has been ever since.
A list of Dr. Epstein’s publications may be found here.
- “X-Ray Spectroscopy of Planar Laser–Plasma Interaction experiments at the National Ignition Facility,” M. J. Rosenberg, R. Epstein, A. A. Solodov, W. Seka, J. F. Myatt, P. A. Michel, M. A. Barrios, D. B. Thorn, M. Hohenberger, J. D. Moody, and S. P. Regan, Phys. Plasmas 26, 012703 (2019).
- “Simulation and Analysis of Time-Gated Monochromatic Radiographs of Cryogenic Implosions on OMEGA,” R. Epstein, C. Stoeckl, V. N. Goncharov, P. W. McKenty, F. J. Marshall, S. P. Regan, R. Betti, W. Bittle, D. R. Harding, S. X. Hu, I. V. Igumenshchev, D. Jacobs-Perkins, R. T. Janezic, J. H. Kelly, T. Z. Kosc, C. Mileham, S. F. B. Morse, P. B. Radha, B. Rice, T. C. Sangster, M. J. Shoup III, W. T. Shmayda, C. Sorce, J. Ulreich, and M. D. Wittman, High Energy Density Phys. 23, 167–177 (2017) (invited).
- “Applications and Results of X-Ray Spectroscopy in Implosion Experiments on the National Ignition Facility,” R. Epstein, S. P. Regan, B. A. Hammel, L. J. Suter, H. A. Scott, M. A. Barrios, D. K. Bradley, D. A. Callahan, C. Cerjan, G. W. Collins, S. N. Dixit, T. Döppner, M. J. Edwards, D. R. Farley, K. B. Fournier, S. Glenn, S. H. Glenzer, I. E. Golovkin, A. Hamza, D. G. Hicks, N. Izumi, O. S. Jones, M. H. Key, J. D. Kilkenny, J. L. Kline, G. A. Kyrala, O. L. Landen, T. Ma, J. J. MacFarlane, A. J. Mackinnon, R. C. Mancini, R. L. McCrory, D. D. Meyerhofer, N. B. Meezan, A. Nikroo, H.-S. Park, P. K. Patel, J. E. Ralph, B. A. Remington, T. C. Sangster, V. A. Smalyuk, P. T. Springer, R. P. J. Town, and J. L. Tucker, AIP Conf. Proc. 1811, 190004 (2017) (invited).
- “Hot-Spot Mix in Ignition-Scale Inertial Confinement Fusion Targets,” S. P. Regan, R. Epstein, B. A. Hammel, L. J. Suter, H. A. Scott, M. A. Barrios, D. K. Bradley, D. A. Callahan, C. Cerjan, G. W. Collins, S. N. Dixit, T. Döppner, M. J. Edwards, D. R. Farley, K. B. Fournier, S. Glenn, S. H. Glenzer, I. E. Golovkin, S. W. Haan, A. Hamza, D. G. Hicks, N. Izumi, O. S. Jones, J. D. Kilkenny, J. L. Kline, G. A. Kyrala, O. L. Landen, T. Ma, J. J. MacFarlane, A. J. MacKinnon, R. C. Mancini, R. L. McCrory, N. B. Meezan, D. D. Meyerhofer, A. Nikroo, H.-S. Park, J. Ralph, B. A. Remington, T. C. Sangster, V. A. Smalyuk, P. T. Springer, and R. P. J. Town, Phys. Rev. Lett. 111, 045001 (2013).
- “On the Bell–Plesset Effects: The Effects of Uniform Compression and Geometrical Convergence on the Classical Rayleigh–Taylor Instability,” R. Epstein, Phys. Plasmas 11, 5114–5124 (2004).
- “Reduction of Time-Averaged Irradiation Speckle Nonuniformity in Laser-Driven Plasmas Due to Target Ablation,” R. Epstein, J. Appl. Phys. 82, 2123–2139 (1997).
- “Electron-Temperature Measurement in Laser-Produced Plasmas by the Ratio of Isoelectronic Line Intensities,” R. S. Marjoribanks, M. C. Richardson, P. A. Jaanimagi, and R. Epstein, Phys. Rev. A 46, R1747–R1750 (1992).
- “Effect of Photoelectric Fluorescence on the Formation of X-Ray Absorption Lines in Laser-Plasma Experiments,” R. Epstein and B. Yaakobi, Phys. Rev. A 44, 5111–5117 (1991).
- “Satellite Absorption Lines and the Temperature Dependence of X-Ray Absorption Features in High-Temperature Plasmas,” R. Epstein, Phys. Rev. A 43, 961–967 (1991).
- “Anticipated Improvement in Laser Beam Uniformity Using Distributed Phase Plates with Quasirandom Patterns,” R. Epstein and S. Skupsky, J. Appl. Phys. 68, 924–931 (1990).
- “Statistical Ray Tracing in Plasmas with Random Density Fluctuations,” R. Epstein and R. S. Craxton, Phys. Rev. A 33, 1892–1902 (1986).
- “Effects of Non-Maxwellian Electron Populations in Non-LTE Simulations of Laser-Plasma Thermal Transport and Implosion Experiments,” R. Epstein, S. Skupsky, and J. Delettrez, J. Quant. Spectrosc. Radiat. Trans. 35, 131–143 (1986).
- “Post-Post-Newtonian Deflection of Light by the Sun,” R. Epstein and I. I. Shapiro, Phys. Rev. D 22, 2947–2949 (1980).
- “The Generation of Gravitational Radiation by Escaping Supernova Neutrinos,” R. Epstein, Astrophys. J. 223, 1037–1045 (1978); 231, 644(E) (1979).
- “The Binary Pulsar: Post-Newtonian Pulse Timing Effects,” R. Epstein, Astrophys. J. 216, 92–100 (1977).
- “Post-Newtonian Generation of Gravitational Waves,” R. Epstein and R. V. Wagoner, Astrophys. J. 197, 717–723 (1975).