1
|
Denoual E, Bergé L, Davoine X, Gremillet L. Modeling terahertz emissions from energetic electrons and ions in foil targets irradiated by ultraintense femtosecond laser pulses. Phys Rev E 2023; 108:065211. [PMID: 38243518 DOI: 10.1103/physreve.108.065211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 11/20/2023] [Indexed: 01/21/2024]
Abstract
Terahertz (THz) emissions from fast electron and ion currents driven in relativistic, femtosecond laser-foil interactions are examined theoretically. We first consider the radiation from the energetic electrons exiting the backside of the target. Our kinetic model takes account of the coherent transition radiation due to these electrons crossing the plasma-vacuum interface as well as of the synchrotron radiation due to their deflection and deceleration in the sheath field they set up in vacuum. After showing that both mechanisms tend to largely compensate each other when all the electrons are pulled back into the target, we investigate the scaling of the net radiation with the sheath field strength. We then demonstrate the sensitivity of this radiation to a percent-level fraction of escaping electrons. We also study the influence of the target thickness and laser focusing. The same sheath field that confines most of the fast electrons around the target rapidly sets into motion the surface ions. We describe the THz emission from these accelerated ions and their accompanying hot electrons by means of a plasma expansion model that allows for finite foil size and multidimensional effects. Again, we explore the dependencies of this radiation mechanism on the laser-target parameters. Under conditions typical of current ultrashort laser-solid experiments, we find that the THz radiation from the expanding plasma is much less energetic-by one to three orders of magnitude-than that due to the early-time motion of the fast electrons.
Collapse
Affiliation(s)
- E Denoual
- CEA, DAM, DIF, F-91297 Arpajon, France
- Université Paris-Saclay, CEA, LMCE, F-91680 Bruyères-le-Châtel, France
| | - L Bergé
- CEA, DAM, DIF, F-91297 Arpajon, France
- Université Paris-Saclay, CEA, LMCE, F-91680 Bruyères-le-Châtel, France
- Centre des Lasers Intenses et Applications, Université de Bordeaux-CNRS-CEA, F-33405 Talence Cedex, France
| | - X Davoine
- CEA, DAM, DIF, F-91297 Arpajon, France
- Université Paris-Saclay, CEA, LMCE, F-91680 Bruyères-le-Châtel, France
| | - L Gremillet
- CEA, DAM, DIF, F-91297 Arpajon, France
- Université Paris-Saclay, CEA, LMCE, F-91680 Bruyères-le-Châtel, France
| |
Collapse
|
2
|
Abstract
We experimentally investigated the accelerated proton beam characteristics such as maximum energy and number by varying the incident laser parameters. For this purpose, we varied the laser energy, focal spot size, polarization, and pulse duration. The proton spectra were recorded using a single-shot Thomson parabola spectrometer equipped with a microchannel plate and a high-resolution charge-coupled device with a wide detection range from a few tens of keV to several MeV. The outcome of the experimental findings is discussed in detail and compared to other theoretical works.
Collapse
|
3
|
Woldegeorgis A, Herzer S, Almassarani M, Marathapalli S, Gopal A. Modeling terahertz emission from the target rear side during intense laser-solid interactions. Phys Rev E 2019; 100:053204. [PMID: 31869893 DOI: 10.1103/physreve.100.053204] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Indexed: 11/07/2022]
Abstract
Relativistic laser-solid target interaction is a powerful source of terahertz radiation where broadband terahertz radiation is emitted from the front and rear surfaces of the target. Even though several experimental works have reported the generation of subpicosecond duration gigawatt peak power terahertz pulses from the target rear surface, the underlying physical process behind their origin is still an open question. Here we discuss a numerical model that can accurately reproduce several aspects of the experimental results. The model is based on the charged particle dynamics at the target rear surface and the evolution of the charge separation field. We identify the major contributors that are responsible for broadband terahertz emission from the rear surface of the target.
Collapse
Affiliation(s)
- A Woldegeorgis
- Institute of Optics and Quantum Electronics, Max-Wien platz 1, 07743 Jena, Germany.,Helmholtz Institute Jena, Fröbelstieg 3, 07743 Jena, Germany
| | - S Herzer
- Institute of Optics and Quantum Electronics, Max-Wien platz 1, 07743 Jena, Germany
| | - M Almassarani
- Institute of Optics and Quantum Electronics, Max-Wien platz 1, 07743 Jena, Germany.,Helmholtz Institute Jena, Fröbelstieg 3, 07743 Jena, Germany
| | - S Marathapalli
- Institute of Optics and Quantum Electronics, Max-Wien platz 1, 07743 Jena, Germany
| | - A Gopal
- Institute of Optics and Quantum Electronics, Max-Wien platz 1, 07743 Jena, Germany.,Helmholtz Institute Jena, Fröbelstieg 3, 07743 Jena, Germany
| |
Collapse
|