Luca Volpe - Academia.edu (original) (raw)
Papers by Luca Volpe
Ion stopping in warm dense matter is a process of fundamental importance for the understanding of... more Ion stopping in warm dense matter is a process of fundamental importance for the understanding of the properties of dense plasmas, the realization and the interpretation of experiments involving ion-beam-heated warm dense matter samples, and for inertial confinement fusion research. The theoretical description of the ion stopping power in warm dense matter is difficult notably due to electron coupling and degeneracy, and measurements are still largely missing. In particular, the low-velocity stopping range around the Bragg peak, that features the largest modeling uncertainties, remains virtually unexplored. Here, we report proton energy-loss measurements in warm dense plasma at unprecedented low projectile velocities, approaching significantly the Bragg-peak region. Our energy-loss data, combined with a precise target characterization based on plasma emission measurements using two independent spectroscopy diagnostics, demonstrate a significant deviation of the stopping power from c...
Optics Letters
In this work, we present a novel and practical method for generating optical vortices in highpowe... more In this work, we present a novel and practical method for generating optical vortices in highpower laser systems. Off-axis spiral phase mirrors are used at oblique angles of incidence in the beam path after amplification and compression allowing for the generation of high-power optical vortices in almost any laser system. An off-axis configuration is possible via modification of the azimuthal gradient of the spiral phase helix and is demonstrated with a simple model using a discrete spiral staircase. This work presents the design, fabrication, and implementation of off-axis spiral phase mirrors in both low and high-power laser systems.
Scientific Reports
Recent advances on laser technology have enabled the generation of ultrashort (fs) high power (PW... more Recent advances on laser technology have enabled the generation of ultrashort (fs) high power (PW) laser systems. For such large scale laser facilities there is an imperative demand for high repetition rate operation in symbiosis with beamlines or end-stations. In such extreme conditions the generation of electromagnetic pulses (EMP) during high intense laser target interaction experiments can tip the scale for the good outcome of the campaign. The EMP effects are several including interference with diagnostic devices and actuators as well as damage of electrical components. The EMP issue is quite known in the picosecond (ps) pulse laser experiments but no systematic study on EMP issues at multi-Joule fs-class lasers has been conducted thus far. In this paper we report the first experimental campaign for EMP-measurements performed at the 200 TW laser system (VEGA 2) at CLPU laser center. EMP pulse energy has been measured as a function of the laser intensity and energy together with...
Scientific Reports
The double laser pulse approach to relativistic electron beam (REB) collimation in solid targets ... more The double laser pulse approach to relativistic electron beam (REB) collimation in solid targets has been investigated at the LULI-ELFIE facility. In this scheme two collinear laser pulses are focused onto a solid target with a given intensity ratio and time delay to generate REBs. The magnetic field generated by the first laser-driven REB is used to guide the REB generated by a second delayed laser pulse. We show how electron beam collimation can be controlled by properly adjusting the ratio of focus size and the delay time between the two pulses. We found that the maximum of electron beam collimation is clearly dependent on the laser focal spot size ratio and related to the magnetic field dynamics. Cu-Kα and CTR imaging diagnostics were implemented to evaluate the collimation effects on the respectively low energy (≤100 keV) and high energy (≥MeV) components of the REB.
High Power Laser Science and Engineering
The Erasmus Plus programme ‘Innovative Education and Training in high power laser plasmas’, other... more The Erasmus Plus programme ‘Innovative Education and Training in high power laser plasmas’, otherwise known as PowerLaPs, is described. The PowerLaPs programme employs an innovative paradigm in that it is a multi-centre programme where teaching takes place in five separate institutes with a range of different aims and styles of delivery. The ‘in class’ time is limited to four weeks a year, and the programme spans two years. PowerLaPs aims to train students from across Europe in theoretical, applied and laboratory skills relevant to the pursuit of research in laser–plasma interaction physics and inertial confinement fusion (ICF). Lectures are intermingled with laboratory sessions and continuous assessment activities. The programme, which is led by workers from the Technological Educational Institute (TEI) of Crete, and supported by co-workers from the Queen’s University Belfast, the University of Bordeaux, the Czech Technical University in Prague, Ecole Polytechnique, the University ...
Plasma Physics and Controlled Fusion
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
In this paper we specify the experimental parameters required to operate a Free Electron Laser wi... more In this paper we specify the experimental parameters required to operate a Free Electron Laser with a laser wiggler in the Angstrom region. Both the quantum and the classical regimes are discussed. The quantum regime of SASE can be reached with more realistic parameters than the classical one. The fundamental feature of the quantum SASE is the extremely narrow single-line radiation spectrum, whose line width can be four orders of magnitude smaller than the bandwidth of the classical spiky SASE spectrum.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
ABSTRACT
IEEE Transactions on Plasma Science, 2016
Nukleonika, 2016
We present the general challenges of plasma diagnostics for laser-produced plasmas and give a few... more We present the general challenges of plasma diagnostics for laser-produced plasmas and give a few more detailed examples: spherically bent crystals for X-ray imaging, velocity interferometers (VISAR) for shock studies, and proton radiography.
This paper presents the results of experiments conducted within the Work Package 10 (fusion exper... more This paper presents the results of experiments conducted within the Work Package 10 (fusion experimental programme) of the HiPER project. The aim of these experiments was to study the physics relevant for advanced ignition schemes for inertial confinement fusion, i.e. the fast ignition and the shock ignition. Such schemes allow to achieve a higher fusion gain compared to the indirect drive approach adopted in the National Ignition Facility in United States, which is important for the future inertial fusion energy reactors and for realising the inertial fusion with smaller facilities.
Journal of Laser Micro/Nanoengineering, 2013
The ablation process of the tooth (enamel, dentin and dentin-enamel junction) by 40 ps laser puls... more The ablation process of the tooth (enamel, dentin and dentin-enamel junction) by 40 ps laser pulses was investigated at 532 nm and 266 nm wavelengths. Fluorescence and scanning electron microscope (SEM) were used as diagnostics. The ablation threshold fluence was measured to be F th ~ 5 J/cm 2 for enamel and for dentin. Ablation at 532 nm laser wavelength produced a crater, both in enamel and dentin, characterized by rough borders. The behavior is completely different at 266 nm wavelength due to the selective behavior towards ablating the intertubular dentin. At 266 nm, the ablation threshold was measured to be F th ~0.3 J/cm 2 for dentin.
Physical Review E, 2014
Controlling the divergence of laser-driven fast electrons is compulsory to meet the ignition requ... more Controlling the divergence of laser-driven fast electrons is compulsory to meet the ignition requirements in the fast ignition inertial fusion scheme. It was shown recently that using two consecutive laser pulses one can improve the electron-beam collimation. In this paper we propose an extension of this method by using a sequence of several laser pulses with a gradually increasing intensity. Profiling the laser-pulse intensity opens a possibility to transfer to the electron beam a larger energy while keeping its divergence under control. We present numerical simulations performed with a radiation hydrodynamic code coupled to a reduced kinetic module. Simulation with a sequence of three laser pulses shows that the proposed method allows one to improve the efficiency of the double pulse scheme at least by a factor of 2. This promises to provide an efficient energy transport in a dense matter by a collimated beam of fast electrons, which is relevant for many applications such as ion-beam sources and could present also an interest for fast ignition inertial fusion.
ABSTRACT The interaction of 40 ps pulse duration laser emitting at 532 nm wavelength with human d... more ABSTRACT The interaction of 40 ps pulse duration laser emitting at 532 nm wavelength with human dental tissue (enamel, dentin, and dentin–enamel junction) has been investigated. The crater profile and the surface morphology have been studied by using a confocal auto-fluorescence microscope (working in reflection mode) and a scanning electron microscope. Crater profile and crater morphology were studied after applying consecutive laser pulses and it was found that the ablation depth increases with the number of consecutive pulses, leaving the crater diameter unchanged. We found that the thermal damage is reduced by using short duration laser pulses, which implies an increased retention of restorative material. We observe carbonization of the irradiated samples, which does not imply changes in the chemical composition. Finally, the use of 40 ps pulse duration laser may become a state of art in conservative dentistry.
Ion stopping in warm dense matter is a process of fundamental importance for the understanding of... more Ion stopping in warm dense matter is a process of fundamental importance for the understanding of the properties of dense plasmas, the realization and the interpretation of experiments involving ion-beam-heated warm dense matter samples, and for inertial confinement fusion research. The theoretical description of the ion stopping power in warm dense matter is difficult notably due to electron coupling and degeneracy, and measurements are still largely missing. In particular, the low-velocity stopping range around the Bragg peak, that features the largest modeling uncertainties, remains virtually unexplored. Here, we report proton energy-loss measurements in warm dense plasma at unprecedented low projectile velocities, approaching significantly the Bragg-peak region. Our energy-loss data, combined with a precise target characterization based on plasma emission measurements using two independent spectroscopy diagnostics, demonstrate a significant deviation of the stopping power from c...
Optics Letters
In this work, we present a novel and practical method for generating optical vortices in highpowe... more In this work, we present a novel and practical method for generating optical vortices in highpower laser systems. Off-axis spiral phase mirrors are used at oblique angles of incidence in the beam path after amplification and compression allowing for the generation of high-power optical vortices in almost any laser system. An off-axis configuration is possible via modification of the azimuthal gradient of the spiral phase helix and is demonstrated with a simple model using a discrete spiral staircase. This work presents the design, fabrication, and implementation of off-axis spiral phase mirrors in both low and high-power laser systems.
Scientific Reports
Recent advances on laser technology have enabled the generation of ultrashort (fs) high power (PW... more Recent advances on laser technology have enabled the generation of ultrashort (fs) high power (PW) laser systems. For such large scale laser facilities there is an imperative demand for high repetition rate operation in symbiosis with beamlines or end-stations. In such extreme conditions the generation of electromagnetic pulses (EMP) during high intense laser target interaction experiments can tip the scale for the good outcome of the campaign. The EMP effects are several including interference with diagnostic devices and actuators as well as damage of electrical components. The EMP issue is quite known in the picosecond (ps) pulse laser experiments but no systematic study on EMP issues at multi-Joule fs-class lasers has been conducted thus far. In this paper we report the first experimental campaign for EMP-measurements performed at the 200 TW laser system (VEGA 2) at CLPU laser center. EMP pulse energy has been measured as a function of the laser intensity and energy together with...
Scientific Reports
The double laser pulse approach to relativistic electron beam (REB) collimation in solid targets ... more The double laser pulse approach to relativistic electron beam (REB) collimation in solid targets has been investigated at the LULI-ELFIE facility. In this scheme two collinear laser pulses are focused onto a solid target with a given intensity ratio and time delay to generate REBs. The magnetic field generated by the first laser-driven REB is used to guide the REB generated by a second delayed laser pulse. We show how electron beam collimation can be controlled by properly adjusting the ratio of focus size and the delay time between the two pulses. We found that the maximum of electron beam collimation is clearly dependent on the laser focal spot size ratio and related to the magnetic field dynamics. Cu-Kα and CTR imaging diagnostics were implemented to evaluate the collimation effects on the respectively low energy (≤100 keV) and high energy (≥MeV) components of the REB.
High Power Laser Science and Engineering
The Erasmus Plus programme ‘Innovative Education and Training in high power laser plasmas’, other... more The Erasmus Plus programme ‘Innovative Education and Training in high power laser plasmas’, otherwise known as PowerLaPs, is described. The PowerLaPs programme employs an innovative paradigm in that it is a multi-centre programme where teaching takes place in five separate institutes with a range of different aims and styles of delivery. The ‘in class’ time is limited to four weeks a year, and the programme spans two years. PowerLaPs aims to train students from across Europe in theoretical, applied and laboratory skills relevant to the pursuit of research in laser–plasma interaction physics and inertial confinement fusion (ICF). Lectures are intermingled with laboratory sessions and continuous assessment activities. The programme, which is led by workers from the Technological Educational Institute (TEI) of Crete, and supported by co-workers from the Queen’s University Belfast, the University of Bordeaux, the Czech Technical University in Prague, Ecole Polytechnique, the University ...
Plasma Physics and Controlled Fusion
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
In this paper we specify the experimental parameters required to operate a Free Electron Laser wi... more In this paper we specify the experimental parameters required to operate a Free Electron Laser with a laser wiggler in the Angstrom region. Both the quantum and the classical regimes are discussed. The quantum regime of SASE can be reached with more realistic parameters than the classical one. The fundamental feature of the quantum SASE is the extremely narrow single-line radiation spectrum, whose line width can be four orders of magnitude smaller than the bandwidth of the classical spiky SASE spectrum.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
ABSTRACT
IEEE Transactions on Plasma Science, 2016
Nukleonika, 2016
We present the general challenges of plasma diagnostics for laser-produced plasmas and give a few... more We present the general challenges of plasma diagnostics for laser-produced plasmas and give a few more detailed examples: spherically bent crystals for X-ray imaging, velocity interferometers (VISAR) for shock studies, and proton radiography.
This paper presents the results of experiments conducted within the Work Package 10 (fusion exper... more This paper presents the results of experiments conducted within the Work Package 10 (fusion experimental programme) of the HiPER project. The aim of these experiments was to study the physics relevant for advanced ignition schemes for inertial confinement fusion, i.e. the fast ignition and the shock ignition. Such schemes allow to achieve a higher fusion gain compared to the indirect drive approach adopted in the National Ignition Facility in United States, which is important for the future inertial fusion energy reactors and for realising the inertial fusion with smaller facilities.
Journal of Laser Micro/Nanoengineering, 2013
The ablation process of the tooth (enamel, dentin and dentin-enamel junction) by 40 ps laser puls... more The ablation process of the tooth (enamel, dentin and dentin-enamel junction) by 40 ps laser pulses was investigated at 532 nm and 266 nm wavelengths. Fluorescence and scanning electron microscope (SEM) were used as diagnostics. The ablation threshold fluence was measured to be F th ~ 5 J/cm 2 for enamel and for dentin. Ablation at 532 nm laser wavelength produced a crater, both in enamel and dentin, characterized by rough borders. The behavior is completely different at 266 nm wavelength due to the selective behavior towards ablating the intertubular dentin. At 266 nm, the ablation threshold was measured to be F th ~0.3 J/cm 2 for dentin.
Physical Review E, 2014
Controlling the divergence of laser-driven fast electrons is compulsory to meet the ignition requ... more Controlling the divergence of laser-driven fast electrons is compulsory to meet the ignition requirements in the fast ignition inertial fusion scheme. It was shown recently that using two consecutive laser pulses one can improve the electron-beam collimation. In this paper we propose an extension of this method by using a sequence of several laser pulses with a gradually increasing intensity. Profiling the laser-pulse intensity opens a possibility to transfer to the electron beam a larger energy while keeping its divergence under control. We present numerical simulations performed with a radiation hydrodynamic code coupled to a reduced kinetic module. Simulation with a sequence of three laser pulses shows that the proposed method allows one to improve the efficiency of the double pulse scheme at least by a factor of 2. This promises to provide an efficient energy transport in a dense matter by a collimated beam of fast electrons, which is relevant for many applications such as ion-beam sources and could present also an interest for fast ignition inertial fusion.
ABSTRACT The interaction of 40 ps pulse duration laser emitting at 532 nm wavelength with human d... more ABSTRACT The interaction of 40 ps pulse duration laser emitting at 532 nm wavelength with human dental tissue (enamel, dentin, and dentin–enamel junction) has been investigated. The crater profile and the surface morphology have been studied by using a confocal auto-fluorescence microscope (working in reflection mode) and a scanning electron microscope. Crater profile and crater morphology were studied after applying consecutive laser pulses and it was found that the ablation depth increases with the number of consecutive pulses, leaving the crater diameter unchanged. We found that the thermal damage is reduced by using short duration laser pulses, which implies an increased retention of restorative material. We observe carbonization of the irradiated samples, which does not imply changes in the chemical composition. Finally, the use of 40 ps pulse duration laser may become a state of art in conservative dentistry.