Self-generated Terahertz Radiation and Relativistic Optics: A Novel Diagnostic for Table top Laser Particle Accelerators

• Applicant: Privatdozentin Dr. Amrutha Gopal
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2013 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 235297462

The project focuses on the spatio-temporal characterization of the Target Normal Sheath Acceleration (TNSA) field which is responsible for the acceleration of ions and protons during relativistic laser-solid interaction. Theoretical studies have predicted that these fields are of the order of TV/m, localized in a spatial dimension comparable to the laser wavelength and may last several times the laser pulse duration. The extreme spatio-temporal characteristics of these fields make them difficult to be accessed by external probes.In this project we propose a novel, non-invasive diagnostic for the accurate measurement of these fields. The principle is simple but allows a truly powerful characterization of these extreme fields. Due to the transient nature of the TNSA field, the electron-ion sheath at the rear of the target should act as an oscillating dipole. This accelerated motion of charged particles induces electromagnetic radiation in the THz frequency domain. Initial experiments were carried out at the JETI (JEna TI-Sapphire system) laser facility at the IOQ (Institute for Optics and Quantum electronics in cooperation with the IPHT (Institute of Photonic Technology) Jena. Based on the promising results from these experiments we aim at investigating systematically the TNSA by means of both advanced THz diagnostics and computer simulation studies using Plasma Simulation Code. The ultimate goal is to relate the features of the emitted THz radiation to the dynamics of the TNSA field, and thus developing a unique diagnostic tool which can be employed to optimise the ion acceleration with lasers.

• DFG Programme: Research Grants