Photoelectric Emission Studies from Crystalline Silicon at 266 Nm

1983 ◽  
Vol 23 ◽  
Author(s):  
A. M. Malvezzi ◽  
J. M. Liu ◽  
N. Bloembergen
Keyword(s):  
Laser Pulse ◽  
Space Charge ◽  
Thermal Equilibrium ◽  
Crystalline Silicon ◽  
Laser Pulses ◽  
Light Fluence ◽  
Highly Nonlinear ◽  
Electron Emissions ◽  
Ion Emission ◽  
Emission Studies

ABSTRACTThree different photoelectric regimes are observed in the interaction of 15 ps, 266 nm laser pulses with crystalline silicon samples versus light fluence. A superposition of linear and quadratic photoionization is followed by a space charge limited regime up to the critical fluence F4ωth for the surface amorphization where highly nonlinear ion emission is observed. Ion and electron emissions become equal in magnitude at a fluence - ∼ 2F4ωth The absence of observable thermionic effects indicates that thermal equilibrium of the electronhole plasma and the lattice is reached during the laser pulse duration.

scholarly journals Ultra-intense laser pulses in near-critical underdense plasmas – radiation reaction and energy partitioning

2017 ◽  
Vol 83 (2) ◽  
Author(s):  
Erik Wallin ◽  
Arkady Gonoskov ◽  
Christopher Harvey ◽  
Olle Lundh ◽  
Mattias Marklund
Keyword(s):  
Laser Pulse ◽  
Pulse Propagation ◽  
Laser Energy ◽  
Radiation Reaction ◽  
Laser Pulses ◽  
High Energy ◽  
Intense Laser ◽  
Long Distance ◽  
Weakly Nonlinear ◽  
Highly Nonlinear

Although, for current laser pulse energies, the weakly nonlinear regime of laser wakefield acceleration is known to be the optimal for reaching the highest possible electron energies, the capabilities of upcoming large laser systems will provide the possibility of running highly nonlinear regimes of laser pulse propagation in underdense or near-critical plasmas. Using an extended particle-in-cell (PIC) model that takes into account all the relevant physics, we show that such regimes can be implemented with external guiding for a relatively long distance of propagation and allow for the stable transformation of laser energy into other types of energy, including the kinetic energy of a large number of high energy electrons and their incoherent emission of photons. This is despite the fact that the high intensity of the laser pulse triggers a number of new mechanisms of energy depletion, which we investigate systematically.

scholarly journals MAXIMIZING BRIGHTNESS IN PHOTOINJECTORS

2007 ◽  
Vol 22 (22) ◽  
pp. 3864-3881 ◽  
Author(s):  
C. LIMBORG-DEPREY ◽  
H. TOMIZAWA
Keyword(s):  
Laser Pulse ◽  
Space Charge ◽  
Numerical Simulations ◽  
Electron Distribution ◽  
Laser Pulses ◽  
Charge Effects ◽  
Emittance Growth ◽  
Transverse Emittance ◽  
Standard Linear ◽  
Very High

If the laser pulse driving photoinjectors could be arbitrarily shaped, the emittance growth induced by space charge effects could be totally compensated for. In particular, for RF guns, the photo-electron distribution leaving the cathode should be close to a uniform distribution contained in a 3D-ellipsoid contour. For photo-cathodes which have very fast emission times, and assuming a perfectly uniform emitting surface, this could be achieved by shaping the laser in a pulse of constant fluence and limited in space by a 3D-ellipsoid contour. Simulations show that in such conditions, with the standard linear emittance compensation, the emittance at the end of the photo-injector beamline approaches the minimum value imposed by the cathode emittance. Brightness, which is expressed as the ratio of peak current over the product of the two transverse emittance, seems to be maximized for small charges. Numerical simulations also show that for very high charge per bunch (10nC), emittances as small as 2 mm-mrad could be reached by using 3D-ellipsoidal laser pulses in an S-Band gun. The production of 3D-ellipsoidal pulses is very challenging, but seems worthwhile the effort. We briefly discuss some of the present ideas and difficulties of achieving such pulses.

scholarly journals Production of ion beams in high-power laser–plasma interactions and their applications

2004 ◽  
Vol 22 (1) ◽  
pp. 19-24 ◽  
Author(s):  
F. PEGORARO ◽  
S. ATZENI ◽  
M. BORGHESI ◽  
S. BULANOV ◽  
T. ESIRKEPOV ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Medical Physics ◽  
Ion Beam ◽  
Laser Pulses ◽  
Ion Beams ◽  
Laser Plasma Interactions ◽  
Physical Mechanisms ◽  
Short Laser Pulses ◽  
Laser Pulse Intensity ◽  
Target Design

Energetic ion beams are produced during the interaction of ultrahigh-intensity, short laser pulses with plasmas. These laser-produced ion beams have important applications ranging from the fast ignition of thermonuclear targets to proton imaging, deep proton lithography, medical physics, and injectors for conventional accelerators. Although the basic physical mechanisms of ion beam generation in the plasma produced by the laser pulse interaction with the target are common to all these applications, each application requires a specific optimization of the ion beam properties, that is, an appropriate choice of the target design and of the laser pulse intensity, shape, and duration.

scholarly journals Electron Symmetry Breaking during Attosecond Charge Migration Induced by Laser Pulses: Point Group Analyses for Quantum Dynamics

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 205
Author(s):  
Dietrich Haase ◽  
Gunter Hermann ◽  
Jörn Manz ◽  
Vincent Pohl ◽  
Jean Christophe Tremblay
Keyword(s):  
Laser Pulse ◽  
Symmetry Breaking ◽  
Electric Fields ◽  
Quantum Dynamics ◽  
Point Group ◽  
Laser Pulses ◽  
Charge Migration ◽  
Laser Control ◽  
The One ◽  
Superposition States

Quantum simulations of the electron dynamics of oriented benzene and Mg-porphyrin driven by short (<10 fs) laser pulses yield electron symmetry breaking during attosecond charge migration. Nuclear motions are negligible on this time domain, i.e., the point group symmetries G = D6h and D4h of the nuclear scaffolds are conserved. At the same time, the symmetries of the one-electron densities are broken, however, to specific subgroups of G for the excited superposition states. These subgroups depend on the polarization and on the electric fields of the laser pulses. They can be determined either by inspection of the symmetry elements of the one-electron density which represents charge migration after the laser pulse, or by a new and more efficient group-theoretical approach. The results agree perfectly with each other. They suggest laser control of symmetry breaking. The choice of the target subgroup is restricted, however, by a new theorem, i.e., it must contain the symmetry group of the time-dependent electronic Hamiltonian of the oriented molecule interacting with the laser pulse(s). This theorem can also be applied to confirm or to falsify complementary suggestions of electron symmetry breaking by laser pulses.

scholarly journals Cylindrically and non-cylindrically symmetric expansion dynamics of tin microdroplets after ultrashort laser pulse impact

2021 ◽  
Vol 127 (2) ◽  
Author(s):  
Tiago de Faria Pinto ◽  
Jan Mathijssen ◽  
Randy Meijer ◽  
Hao Zhang ◽  
Alex Bayerle ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Droplet Deformation ◽  
Cylindrically Symmetric ◽  
Linearly Polarized ◽  
Particle Hydrodynamics ◽  
Deformation Dynamics ◽  
Smoothed Particle ◽  
Asymmetric Shock

AbstractIn this work, the expansion dynamics of liquid tin micro-droplets irradiated by femtosecond laser pulses were investigated. The effects of laser pulse duration, energy, and polarization on ablation, cavitation, and spallation dynamics were studied using laser pulse durations ranging from 220 fs to 10 ps, with energies ranging from 1 to 5 mJ, for micro-droplets with an initial radius of 15 and 23 $$\upmu$$ μ m. Using linearly polarized laser pulses, cylindrically asymmetric shock waves were produced, leading to novel non-symmetric target shapes, the asymmetry of which was studied as a function of laser pulse parameters and droplet size. A good qualitative agreement was obtained between smoothed-particle hydrodynamics simulations and high-resolution stroboscopic experimental data of the droplet deformation dynamics.

ENERGETIC PROTON ACCELERATION BY ULTRAINTENSE LASER PULSES IN INHOMOGENEOUS PLASMA TARGETS

2007 ◽  
Vol 21 (03n04) ◽  
pp. 642-646 ◽  
Author(s):  
A. ABUDUREXITI ◽  
Y. MIKADO ◽  
T. OKADA
Keyword(s):  
Laser Pulse ◽  
Inhomogeneous Plasma ◽  
Laser Pulses ◽  
Proton Acceleration ◽  
Particle In Cell ◽  
Target Plasma ◽  
Plasma Target ◽  
Experimental Process ◽  
Foil Target ◽  
Proton Bunch

Particle-in-Cell (PIC) simulations of fast particles produced by a short laser pulse with duration of 40 fs and an intensity of 1020W/cm2 interacting with a foil target are performed. The experimental process is numerically simulated by considering a triangular concave target illuminated by an ultraintense laser. We have demonstrated increased acceleration and higher proton energies for triangular concave targets. We also determined the optimum target plasma conditions for maximum proton acceleration. The results indicated that a change in the plasma target shape directly affects the degree of contraction accelerated proton bunch.

Ultrafast dynamic reflectivity of vanadium pentoxide

2008 ◽  
Vol 23 (2) ◽  
pp. 308-311 ◽  
Author(s):  
Gregory J. Taft ◽  
Matthew T. Newby ◽  
Joel J. Hrebik ◽  
Marshall Onellion ◽  
Thomas F. George ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Vanadium Pentoxide ◽  
Linear Polarization ◽  
Laser Pulses ◽  
Acoustic Vibrations ◽  
Frequency Oscillation ◽  
Ultrafast Dynamic ◽  
Transverse Acoustic ◽  
Wave Numbers ◽  
Lower Frequency Oscillation

The ultrafast dynamic reflectivity of vanadium pentoxide is measured using 40 fs pulses from a self-mode-locked Ti:sapphire laser. The laser pulses excite acoustic vibrations at wave numbers of 145 and 103 cm−1. The amplitudes of the induced oscillations depend strongly on the orientation between the linear polarization of the laser pulses and the crystal axes, with the largest oscillations observed for an orientation of 45°. The higher-frequency oscillation is induced immediately upon arrival of the laser pulse, while the lower-frequency oscillation appears a few picoseconds later. The oscillations persist for approximately 10 ps after the arrival of the pulse. The oscillations are attributed to transverse acoustic modes propagating along the a-axis of the crystal.

scholarly journals Nonperturbative generation of above-threshold harmonics from pre-excited argon atoms in intense mid-infrared laser fields

2017 ◽  
Vol 5 ◽  
Author(s):  
Guihua Li ◽  
Hongqiang Xie ◽  
Ziting Li ◽  
Jinping Yao ◽  
Wei Chu ◽  
...  
Keyword(s):  
Excited State ◽  
Femtosecond Laser ◽  
Pulse Energy ◽  
Laser Pulses ◽  
Infrared Laser ◽  
Femtosecond Laser Pulses ◽  
Probe Laser ◽  
Laser Fields ◽  
Mid Infrared ◽  
Highly Nonlinear

We experimentally investigate the generation of above-threshold harmonics completely from argon atoms on an excited state using mid-infrared femtosecond laser pulses. The highly nonlinear dependences of the observed signal on the pulse energy and polarization of the probe laser pulses indicate its nonperturbative characteristic.

scholarly journals Electron and photon beams interacting with plasma

2006 ◽  
Vol 364 (1840) ◽  
pp. 635-645 ◽  
Author(s):  
Albert Reitsma ◽  
Dino Jaroszynski
Keyword(s):  
Laser Pulse ◽  
Electron Bunch ◽  
Laser Pulses ◽  
Plasma Waves ◽  
Intense Laser ◽  
Wave Number ◽  
Collective Effects ◽  
Photon Beams ◽  
Wave Dynamics ◽  
Intense Laser Pulses

A comparison is made between the interaction of electron bunches and intense laser pulses with plasma. The laser pulse is modelled with photon kinetic theory , i.e. a representation of the electromagnetic field in terms of classical quasi-particles with space and wave number coordinates, which enables a direct comparison with the phase space evolution of the electron bunch. Analytical results are presented of the plasma waves excited by a propagating electron bunch or laser pulse, the motion of electrons or photons in these plasma waves and collective effects, which result from the self-consistent coupling of the particle and plasma wave dynamics.

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