5A10(a) - Short-pulse Q-switched laser with variable pulse length

1966 ◽  
Vol 2 (9) ◽  
pp. 436-441 ◽  
Author(s):  
R. Ambartsumyan ◽  
N. Basov ◽  
V. Zuev ◽  
P. Kryukov ◽  
V. Letokhov
Keyword(s):  
Short Pulse ◽  
Pulse Length

LIMITS ON PRODUCTION OF NARROW BAND PHOTONS FROM INVERSE COMPTON SCATTERING

2007 ◽  
Vol 22 (23) ◽  
pp. 4333-4342 ◽  
Author(s):  
J. ROSENZWEIG ◽  
O. WILLIAMS
Keyword(s):  
Compton Scattering ◽  
Laser Energy ◽  
Short Pulse ◽  
Pulse Length ◽  
Pulse Electron Beam ◽  
Intense Laser ◽  
Scattered Photon ◽  
Inverse Compton Scattering ◽  
Inverse Compton ◽  
Wavelength Radiation

In using the inverse Compton scattering (ICS) interaction as a high brilliance, short wavelength radiation source, one collides two beams, one an intense laser, and the other a high charge, short pulse electron beam. In order to maximize the flux of photons from ICS, one must focus both beams strongly, which implies both use of short beams and the existence of large angles in the interaction. One aspect of brilliance is the narrowness of the wavelength band emitted by the source. This paper explores the limits of ICS-based source brilliance based on inherent wavelength broadening effects that arise due to focal angles, laser energy density, and finite laser pulse length effects. It is shown that for a nominal 1% desired bandwidth, that one obtains approximately one scattered photon per electron in a head-on collision geometry.

Excimer Laser Liftoff of Epitaxial Pb(Zr,Ti)O3 Thin Films and Heterostructures

1999 ◽  
Vol 596 ◽  
Author(s):  
L. Tsakalakos ◽  
T. Sands
Keyword(s):  
Thin Films ◽  
Excimer Laser ◽  
Short Pulse ◽  
Pulse Length ◽  
Transient Liquid Phase ◽  
Film Stress ◽  
Growth Substrate ◽  
Localized Heating ◽  
Krf Excimer Laser ◽  
Local Relaxation

AbstractEpitaxial (100) and (111)-oriented Pb(Zr,Ti)O3-based thin films and heterostructures have been transferred intact from their sapphire and MgO growth substrates to silicon and polymer substrates utilizing a novel laser liftoff process. The heterostructures, while on their growth substrate, were bonded to the receptor substrates using one of several bonding methods, including van der Waals bonding to an elastomer receptor, and transient liquid-phase Pd-In bonding to Si. A single 38 ns pulse from a KrF excimer laser (<,= 248 nm) directed through the transparent growth substrate induced localized heating of the perovskite interfacial layer. At fluences corresponding to the onset of vaporization (>300 mJ/cm2), the sapphire or MgO substrate was detached. Because of the short pulse length and the low thermal conductivity of Pb-based perovskite phases, heating of the top surface of the heterostructure was minimal, thus permitting film transfer to thermally-sensitive receptor substrates. X-ray rocking curves revealed slight broadening of the principal PLZT diffraction peaks (∼10–20%), suggesting local relaxation of film stress.

Recent Developments and Future Plans for the Accelerator Based Slow Positron Facilities at AIST

2012 ◽  
Vol 733 ◽  
pp. 285-290 ◽  
Author(s):  
Brian E. O'Rourke ◽  
Nagayasu Oshima ◽  
Atsushi Kinomura ◽  
Toshiyuki Ohdaira ◽  
Ryoichi Suzuki
Keyword(s):  
Short Pulse ◽  
Pulse Length ◽  
Fiscal Year ◽  
Beam Diameter ◽  
Slow Positron ◽  
Transport Efficiency ◽  
Recent Developments ◽  
Positron Lifetime Spectroscopy ◽  
Superconducting Accelerator ◽  
Positron Production

We describe the recent installation of a new slow positron beamline at AIST and our plans to develop a dedicated superconducting accelerator for positron production. The new positron beamline is already installed and should be operational by the end of this fiscal year (March 2012). Initially positrons will be generated using a 70 MeV electron beam from the existing accelerator directed onto a newly installed converter and moderator assembly. The beamline has two experimental ports both dedicated to positron lifetime spectroscopy, one port with a focused beam (diameter ~ 30 microm) and the other unfocussed (~ 10 mm). A superconducting accelerator for positron production is currently under development. When completed, it will deliver a high frequency (~ MHz), high current (~ mA), short pulse length (< 100 ps) beam to the positron production target. We investigate the possibility of transporting the positron pulses thus produced directly onto samples for lifetime measurement. Such a scheme would remove the necessity for pulse stretching and chopping which is required with the existing LINAC and should allow for greatly increased slow positron transport efficiency.

Monte Carlo Simulation of the Laser-Induced Temperature Dynamics in Very Thin Scattering and Absorbing Biological Layer Piles

2018 ◽  
Author(s):  
Reginald C. Eze
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Radiation Transport ◽  
Short Pulse ◽  
Pulse Length ◽  
Thin Layers ◽  
Thermal Dissipation ◽  
Traditional Model ◽  
Target Area ◽  
Temperature Dynamics

Radiative-thermal models of light transport in tissue are presented that stimulates the thermal effects of pulsed laser radiation on very thin scattering and absorbing biological layers. Thermal therapies require a firm understanding of temperature-depth relationship for tissue modification or destruction, especially through very thin layers that are characterized by contrasting opto-thermal properties. Temperature distribution in biological layers of thicknesses in the order of their mean free path or less are evaluated before the onset of thermal diffusion for both the traditional model of Monte Carlo simulation and that with new features tailored for very thin layers. Temperature dynamics in very thin layers such as skin in dermatology is a typical example. For instance, during the heating of small volumes of tissue as in fractional photothermolysis, nonablative dermal remodeling and ablative skin resurfacing, short pulse lasers are used by choosing pulse length sufficiently short that will not damage the surrounding healthy tissue, but sufficiently long enough to allow damage, necrosis or coagulation over the entire target area. This is in contrast to the situation where thermal dissipation due to heat conduction is the principal determinant of tissue damage. Numerical results obtained from both models differ significantly. While the model designed specifically for very thin scattering layers tends to confine temperature rise to specific layers, the traditional model have a tendency to misjudge the layers of interest thereby giving rise to temperature increase in undesired locations. These results will advance our understanding of radiation transport in layers that are extremely very thin, and help develop better treatment modules for laser therapeutic treatment regimes in surgery and dermatology.

scholarly journals Radio Echo Sounding On Temperate Glaciers

1975 ◽  
Vol 14 (70) ◽  
pp. 57-69 ◽  
Author(s):  
R. H. Goodman
Keyword(s):  
Short Pulse ◽  
Pulse Length ◽  
Beam Width ◽  
Field Trials ◽  
Water Levels ◽  
Quality Data ◽  
Real Time Analysis ◽  
Radio Echo Sounding ◽  
Excellent Spatial Resolution ◽  
Echo Sounder

A high-resolution radio echo sounder operating at a frequency of 620 MHz has been developed for studies of temperate glaciers. Excellent spatial resolution is obtained through the use of a short pulse length (70 ns) and an antenna beam width of 5.2°. Large amounts of high-quality data may be rapidly collected since the sounder incorporates an automatic positioning system and an on-line computer. Real time analysis of the echoes facilitates the understanding of complex reflecting horizons observed in temperate glaciers.Results obtained during field trials of the echo sounder on both the Wapta Icefield and Athabasca Glacier are given. Intraglacial structures which may be due to water levels within the ice have been detected.

Laser Desorption Combined with Laser Postionization for Mass Spectrometry

2019 ◽  
Vol 12 (1) ◽  
pp. 225-245 ◽  
Author(s):  
Luke Hanley ◽  
Raveendra Wickramasinghe ◽  
Yeni P. Yung
Keyword(s):  
Mass Spectrometry ◽  
Near Infrared ◽  
Extreme Ultraviolet ◽  
Short Pulse ◽  
Ambient Pressure ◽  
Pulse Length ◽  
Ultrashort Pulses ◽  
High Sensitivity ◽  
Laser Desorption ◽  
Direct Laser

Lasers with pulse lengths from nanoseconds to femtoseconds and wavelengths from the mid-infrared to extreme ultraviolet (UV) have been used for desorption or ablation in mass spectrometry. Such laser sampling can often benefit from the addition of a second laser for postionization of neutrals. The advantages offered by laser postionization include the ability to forego matrix application, high lateral resolution, decoupling of ionization from desorption, improved analysis of electrically insulating samples, and potential for high sensitivity and depth profiling while minimizing differential detection. A description of postionization by vacuum UV radiation is followed by a consideration of multiphoton, short pulse, and other postionization strategies. The impacts of laser pulse length and wavelength are considered for laser desorption or laser ablation at low pressures. Atomic and molecular analysis via direct laser desorption/ionization using near-infrared ultrashort pulses is described. Finally, the postionization of clusters, the role of gaseous collisions, sampling at ambient pressure, atmospheric pressure photoionization, and the addition of UV postionization to MALDI are considered.

scholarly journals Divertor heat flux challenge and mitigation in SPARC

2020 ◽  
Vol 86 (5) ◽  
Author(s):  
A. Q. Kuang ◽  
S. Ballinger ◽  
D. Brunner ◽  
J. Canik ◽  
A. J. Creely ◽  
...  
Keyword(s):  
Heat Flux ◽  
Short Pulse ◽  
Fusion Energy ◽  
Pulse Length ◽  
Target Surface ◽  
Theoretical Models ◽  
Baseline Scenario ◽  
Parallel Edge ◽  
Compact Size ◽  
Order Of Magnitude

Owing to its high magnetic field, high power, and compact size, the SPARC experiment will operate with divertor conditions at or above those expected in reactor-class tokamaks. Power exhaust at this scale remains one of the key challenges for practical fusion energy. Based on empirical scalings, the peak unmitigated divertor parallel heat flux is projected to be greater than 10 GW m−2. This is nearly an order of magnitude higher than has been demonstrated to date. Furthermore, the divertor parallel Edge-Localized Mode (ELM) energy fluence projections (~11–34 MJ m−2) are comparable with those for ITER. However, the relatively short pulse length (~25 s pulse, with a ~10 s flat top) provides the opportunity to consider mitigation schemes unsuited to long-pulse devices including ITER and reactors. The baseline scenario for SPARC employs a ~1 Hz strike point sweep to spread the heat flux over a large divertor target surface area to keep tile surface temperatures within tolerable levels without the use of active divertor cooling systems. In addition, SPARC operation presents a unique opportunity to study divertor heat exhaust mitigation at reactor-level plasma densities and power fluxes. Not only will SPARC test the limits of current experimental scalings and serve for benchmarking theoretical models in reactor regimes, it is also being designed to enable the assessment of long-legged and X-point target advanced divertor magnetic configurations. Experimental results from SPARC will be crucial to reducing risk for a fusion pilot plant divertor design.

scholarly journals FemtoMAX – an X-ray beamline for structural dynamics at the short-pulse facility of MAX IV

2018 ◽  
Vol 25 (2) ◽  
pp. 570-579 ◽  
Author(s):  
Henrik Enquist ◽  
Andrius Jurgilaitis ◽  
Amelie Jarnac ◽  
Åsa U. J. Bengtsson ◽  
Matthias Burza ◽  
...  
Keyword(s):  
Structural Dynamics ◽  
Short Pulse ◽  
Pulse Length ◽  
Interatomic Distances ◽  
Beam Position ◽  
X Ray ◽  
Storage Media ◽  
Functional Dynamics ◽  
Manufacturing Techniques ◽  
Beam Position Monitors

The FemtoMAX beamline facilitates studies of the structural dynamics of materials. Such studies are of fundamental importance for key scientific problems related to programming materials using light, enabling new storage media and new manufacturing techniques, obtaining sustainable energy by mimicking photosynthesis, and gleaning insights into chemical and biological functional dynamics. The FemtoMAX beamline utilizes the MAX IV linear accelerator as an electron source. The photon bursts have a pulse length of 100 fs, which is on the timescale of molecular vibrations, and have wavelengths matching interatomic distances (Å). The uniqueness of the beamline has called for special beamline components. This paper presents the beamline design including ultrasensitive X-ray beam-position monitors based on thin Ce:YAG screens, efficient harmonic separators and novel timing tools.

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