Penetrating Radiation Systems and Applications XIII, 2012
ABSTRACT The 200TW laser system, (Ti:Sapphire CPA system) delivering 5J in 25fs pulse with a 10Hz... more ABSTRACT The 200TW laser system, (Ti:Sapphire CPA system) delivering 5J in 25fs pulse with a 10Hz repetition rate and a contrast ratio of 1:10^-11 at the fundamental 800nm frequency, is used at the Advanced Laser Light Source (ALLS) facility to develop new generation of x-ray and pulsed particle beam sources (electrons, protons, neutrons). Experimental results on the betatron emission and electron emission from high intensity (<10^19 W/cm2) interactions with gas jet targets (1cm long supersonic nozzle) and on proton generation during high intensity (10^20 W/cm2) laser interaction with thin foil (10nm) and thick (several µm) targets will be presented and discussed. With gas jet targets, very high-resolution single shot phase contrast imaging with 10-20 keV X-rays has been demonstrated, and electrons are currently generated in the GeV range. X-ray source characterization will be presented. With foil targets, the target expansion has been measured on both sides of the target as well as proton generation (15 MeV range) at these relativistic intensities with various diagnostics (folding wave interferometer, time of flight, Thomson parabola...) We will describe the progresses we are doing to move from the laboratory experiments system to the application levels with integrated systems and compact light sources, with a special emphasis on medical applications. We are exploring the use of these high power lasers as a basic tool to image in real time with X-rays (betatron emission) tumors during their irradiation by protons (accelerated by the same laser). + funded by NSERC, CIPI, CFI, FQRNT, MDEIE, INRS, CRC program.
ABSTRACT Using a 2.3 J, 32 fs (70 TW) Ti:sapphire laser, we demonstrate highly efficient high-ord... more ABSTRACT Using a 2.3 J, 32 fs (70 TW) Ti:sapphire laser, we demonstrate highly efficient high-order surface harmonic generation from nanometric thin foils. Results show that pulse contrast currently limits the HHG efficiency.
ABSTRACT High intensity femtosecond laser pulses can be used to generate X-ray radiation. In the ... more ABSTRACT High intensity femtosecond laser pulses can be used to generate X-ray radiation. In the laser wakefield process, when a high intensity laser pulse (<1018 W/cm2) is focused onto a gas jet target, it interacts with the instantaneously created under-dense plasma and excites a wakefield wave. In the wakefield electrons are trapped and accelerated to high energies in short distances. The electrons trapped in the wakefield can perform Betatron oscillations across the propagation axis and emit X-ray photons. The Betatron X-ray beam is broadband as the radiation emission has a synchrotron distribution. The X-ray beam is collimated and its pulse duration is femtosecond. For high resolution and phase contrast X-ray imaging applications, the important feature of the X-ray Betatron beam is the μm source size. Using ALLS 100 TW class laser system we demonstrate that the Betatron X-ray beam is both energetic and bright enough to produce single laser shot phase contrast imaging of complex objects located in air.
Focusing a high intensity laser pulse, onto a thin foil target generates a plasma and energetic p... more Focusing a high intensity laser pulse, onto a thin foil target generates a plasma and energetic proton and ion beams from the target rear and front sides, propagating along the target normal. Such laser produced collimated and energetic protons beams are of high interest because of the wide range of applications: ion based fast ignitor schemes, probing of electromagnetic fields
Collimated beams of energetic protons are produced by the interaction of short duration high inte... more Collimated beams of energetic protons are produced by the interaction of short duration high intensity laser pulses with solid foils. This field has been the subject of many studies in the last decade. This interest is motivated by the wide range of application of such beams: ion based fast ignitor schemes, probing of electromagnetic fields in plasma, isotope production or hadron therapy. The recently commissioned 200 TW laser system (5 J, 25 fs, 1010 laser pulse contrast, 10 Hz repetition rate at 800 nm) at the Advanced Laser Light Source (ALLS) facility has been used to study proton acceleration with femtosecond laser pulses. The proton spectrum was characterized using a time of flight detector. Due to the high contrast of the laser pulse, foil targets as thin as 30 nm could be studied.
ABSTRACT A high intensity ultrashort laser pulse, with an intensity of the order of 10^19 W/cm^2,... more ABSTRACT A high intensity ultrashort laser pulse, with an intensity of the order of 10^19 W/cm^2, focused onto a thin foil target generates a plasma and highly energetic ion (including proton) beams from its front and rear sides which propagate along the target normal. Another interest of laser plasma interaction with ultra-thin foil is the possibility to deposit energy in the entire laser absorption depth before any expansion thus enabling target isochoric heating. With a target thickness of 30 or 15 nm the laser pulse should interact in volume and enable to reach very high temperature while the target is still at solid density. The resulting cooling of the target will then be ultra-fast and potential X-ray emission should be ultrashort. The 100 TW class laser system at the Advanced Laser Light Source facility enables laser plasma interaction study with femtosecond laser pulses, ultra thin foil targets and high contrast laser pulse intensity ratio. We used a shadowgraph diagnostic with a femtosecond laser probe to characterize the plasma expansion.
Penetrating Radiation Systems and Applications XIII, 2012
ABSTRACT The 200TW laser system, (Ti:Sapphire CPA system) delivering 5J in 25fs pulse with a 10Hz... more ABSTRACT The 200TW laser system, (Ti:Sapphire CPA system) delivering 5J in 25fs pulse with a 10Hz repetition rate and a contrast ratio of 1:10^-11 at the fundamental 800nm frequency, is used at the Advanced Laser Light Source (ALLS) facility to develop new generation of x-ray and pulsed particle beam sources (electrons, protons, neutrons). Experimental results on the betatron emission and electron emission from high intensity (<10^19 W/cm2) interactions with gas jet targets (1cm long supersonic nozzle) and on proton generation during high intensity (10^20 W/cm2) laser interaction with thin foil (10nm) and thick (several µm) targets will be presented and discussed. With gas jet targets, very high-resolution single shot phase contrast imaging with 10-20 keV X-rays has been demonstrated, and electrons are currently generated in the GeV range. X-ray source characterization will be presented. With foil targets, the target expansion has been measured on both sides of the target as well as proton generation (15 MeV range) at these relativistic intensities with various diagnostics (folding wave interferometer, time of flight, Thomson parabola...) We will describe the progresses we are doing to move from the laboratory experiments system to the application levels with integrated systems and compact light sources, with a special emphasis on medical applications. We are exploring the use of these high power lasers as a basic tool to image in real time with X-rays (betatron emission) tumors during their irradiation by protons (accelerated by the same laser). + funded by NSERC, CIPI, CFI, FQRNT, MDEIE, INRS, CRC program.
ABSTRACT Using a 2.3 J, 32 fs (70 TW) Ti:sapphire laser, we demonstrate highly efficient high-ord... more ABSTRACT Using a 2.3 J, 32 fs (70 TW) Ti:sapphire laser, we demonstrate highly efficient high-order surface harmonic generation from nanometric thin foils. Results show that pulse contrast currently limits the HHG efficiency.
ABSTRACT High intensity femtosecond laser pulses can be used to generate X-ray radiation. In the ... more ABSTRACT High intensity femtosecond laser pulses can be used to generate X-ray radiation. In the laser wakefield process, when a high intensity laser pulse (<1018 W/cm2) is focused onto a gas jet target, it interacts with the instantaneously created under-dense plasma and excites a wakefield wave. In the wakefield electrons are trapped and accelerated to high energies in short distances. The electrons trapped in the wakefield can perform Betatron oscillations across the propagation axis and emit X-ray photons. The Betatron X-ray beam is broadband as the radiation emission has a synchrotron distribution. The X-ray beam is collimated and its pulse duration is femtosecond. For high resolution and phase contrast X-ray imaging applications, the important feature of the X-ray Betatron beam is the μm source size. Using ALLS 100 TW class laser system we demonstrate that the Betatron X-ray beam is both energetic and bright enough to produce single laser shot phase contrast imaging of complex objects located in air.
Focusing a high intensity laser pulse, onto a thin foil target generates a plasma and energetic p... more Focusing a high intensity laser pulse, onto a thin foil target generates a plasma and energetic proton and ion beams from the target rear and front sides, propagating along the target normal. Such laser produced collimated and energetic protons beams are of high interest because of the wide range of applications: ion based fast ignitor schemes, probing of electromagnetic fields
Collimated beams of energetic protons are produced by the interaction of short duration high inte... more Collimated beams of energetic protons are produced by the interaction of short duration high intensity laser pulses with solid foils. This field has been the subject of many studies in the last decade. This interest is motivated by the wide range of application of such beams: ion based fast ignitor schemes, probing of electromagnetic fields in plasma, isotope production or hadron therapy. The recently commissioned 200 TW laser system (5 J, 25 fs, 1010 laser pulse contrast, 10 Hz repetition rate at 800 nm) at the Advanced Laser Light Source (ALLS) facility has been used to study proton acceleration with femtosecond laser pulses. The proton spectrum was characterized using a time of flight detector. Due to the high contrast of the laser pulse, foil targets as thin as 30 nm could be studied.
ABSTRACT A high intensity ultrashort laser pulse, with an intensity of the order of 10^19 W/cm^2,... more ABSTRACT A high intensity ultrashort laser pulse, with an intensity of the order of 10^19 W/cm^2, focused onto a thin foil target generates a plasma and highly energetic ion (including proton) beams from its front and rear sides which propagate along the target normal. Another interest of laser plasma interaction with ultra-thin foil is the possibility to deposit energy in the entire laser absorption depth before any expansion thus enabling target isochoric heating. With a target thickness of 30 or 15 nm the laser pulse should interact in volume and enable to reach very high temperature while the target is still at solid density. The resulting cooling of the target will then be ultra-fast and potential X-ray emission should be ultrashort. The 100 TW class laser system at the Advanced Laser Light Source facility enables laser plasma interaction study with femtosecond laser pulses, ultra thin foil targets and high contrast laser pulse intensity ratio. We used a shadowgraph diagnostic with a femtosecond laser probe to characterize the plasma expansion.
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