Analysis of space-resolved X-ray spectra from laser plasmas

High dynamic range, space-resolved X-ray spectra, obtained using a TlAP crystal and a cooled CCD camera as a detector, were used to investigate the electron density and temperature profiles of an aluminum laser plasma with micrometer resolution. The electron density profile retrieved from the measurements is compared with numerical predictions from the two hydrodynamics codes MEDUSA (1D) and POLLUX (2D). It is shown that 2D density profiles can be successfully reproduced by 1D simulations using a spherical geometry with an ad hoc initial radius, leading to similar electron temperature profiles

A study of laser plasmas as X-ray sources in the 1-10 keV spectral region

An experimental investigation on X-ray emission from laser-produced plasmas is presented and the properties of such an emission of interest for application purposes are examined. Plasmas were generated by focusing 1 μm, 3 ns Nd laser pulses onto Al and Cu targets at an intensity of 1013 W/cm2. The temporal evolution of the emission and its spectral features were investigated by using an X-ray streak-camera and an X-ray photodiode. In the case of Cu targets, the analysis of the emission showed two spectral components. The main component was centered at ≈ 1.2 keV and a minor component, whose intensity was measured to be 10-3 of the previous component, was observed at ≈7 keV. The X-ray conversion efficiency, in the investigated spectral region, was measured to be 1% for Cu targets and 0.3% for Al targets

Multi-GeV Electron Spectrometer

The advance in laser plasma acceleration techniques pushes the regime of the resulting accelerated particles to higher energies and intensities. In particular the upcoming experiments with the FLAME laser at LNF will enter the GeV regime with almost 1pC of electrons. From the current status of understanding of the acceleration mechanism, relatively large angular and energy spreads are expected. There is therefore the need to develop a device capable to measure the energy of electrons over three orders of magnitude (few MeV to few GeV) under still unknown angular divergences. Within the PlasmonX experiment at LNF a spectrometer is being constructed to perform these measurements. It is made of an electro-magnet and a screen made of scintillating fibers for the measurement of the trajectories of the particles. The large range of operation, the huge number of particles and the need to focus the divergence present unprecedented challenges in the design and construction of such a device. We will present the design considerations for this spectrometer and the first results from a prototype.Comment: 7 pages, 6 figures, submitted to NIM

Investigation of ultraintense femtosecond laser–plasma interactions through ω and 2ω imaging and spectroscopy

A laser–plasma interaction experiment was performed in order to match effective conditions for wake-field electron acceleration. A 30-fs pulse was made to interact with a preformed plasma generated via the exploding foil technique from a 1-μm-thick plastic film. The irradiance of the femtosecond pulse in the plasma was 1020 Wcm−2. The interaction conditions were investigated via imaging and spectroscopy at the fundamental and the second harmonic of the laser frequency, both forward and backward. Our data clearly show that conditions suitable for electron acceleration are achieved close to the propagation axis and can be easily reproduced from shot to shot. In contrast, significant growth of instabilities occurs at the boundaries of the interaction region. These observations are consistent with a preliminary evidence of forward acceleration of high-energy electrons. Optical, X-ray, and γ-ray data obtained for different positions of the foil target with respect to the laser focal plane further support this promising scenario

High brightness laser–plasma X-ray source at IFAM: Characterization and applications

A high brightness laser-plasma X-ray source has been set-up and is presently available at IFAM. A wide range of diagnostics has been set up to monitor the properties of the X-ray radiation and to control the main parameters including photon energy, flux intensity, and pulse duration. A beam extractor enables access to the X-ray radiation at atmospheric pressure. A simple, easy-to-use projection microscope has been built which is capable of single-shot micron resolution imaging with digital acquisition. Preliminary biomedical experiments show that the X-ray doses available on a single laser shot exposure of our source fully meet the conditions required for an important class of biological experiments based on X-ray induced DNA damage providing an ideal alternative to the long time exposures needed with X-ray tubes