High Power Laser Science and Engineering, Volume. 7, Issue 3, 03000e45(2019)
Effect of rear surface fields on hot, refluxing and escaping electron populations via numerical simulations
Fig. 1. The electric field in the
Fig. 2. The simulated peak electric field as a function of incident laser intensity. Inset, the peak electric field as a function of the number of relativistic electrons.
Fig. 3. The internal hot-electron temperature (which is discussed further in Section
Fig. 4. The internal and refluxing electron spectra for three different laser intensities. A simple Boltzmann fit was applied to the data and the temperature determined.
Fig. 5. (a) The initial energy of the electrons prior to refluxing plotted as a function of the refluxed energy. The red dotted line represents energy equality before and after interacting with the sheath. (b) The energy difference of the refluxing electrons as a function of time. Some electrons gain energy. The largest gains and loses are observed for electrons which reach the rear of the target at the peak of the electric field.
Fig. 6. The kinetic energy and electric field of a tracked electron as a function of distance. The arrows depict the direction of travel for the electron.
Fig. 7. Similar to Figure
Fig. 8. Internal and escaping electron spectra for three different laser intensities. Also plotted are the escaping electron spectra while those electrons are still inside the target.
Fig. 9. Electron density maps of electrons with energies greater than 1 MeV at the rear of the target at four different time steps. (a) and (b) show the ‘ballistic’ electrons that escape the target. The red dotted line represents the front of these electrons, which is travelling at the speed of light. (c) and (d) are taken at much later time in the simulation. At this time the rear surface sheath has begun to expand. This expansion is much slower, but contains much more electrons than the ballistic escaping electrons.
Fig. 10. Spatial maps of the electric field at the rear of the target at four time steps that coincide with those shown in Figure
Fig. 11. (a) The initial internal electron energy plotted against the ballistic escaping energy. All these electrons appear to lose energy upon leaving the target. (b) The energy difference between the escaping electrons as a function of the time at which they pass the external boundary.
Fig. 12. The kinetic energy and electric field in the
Fig. 13. The change in energy of the escaping electrons as a function of the integrated electric field in the
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D. R. Rusby, C. D. Armstrong, G. G. Scott, M. King, P. McKenna, D. Neely. Effect of rear surface fields on hot, refluxing and escaping electron populations via numerical simulations[J]. High Power Laser Science and Engineering, 2019, 7(3): 03000e45
Category: Research Articles
Received: Mar. 15, 2019
Accepted: Jun. 12, 2019
Published Online: Jul. 26, 2019
The Author Email: D. R. Rusby (rusby1@llnl.gov)