E-beam-pumped semiconductor lasers

Science.gov (United States)

Rice, Robert R.; Shanley, James F.; Ruggieri, Neil F.

1995-04-01

The collapse of the Soviet Union opened many areas of laser technology to the West. E-beam- pumped semiconductor lasers (EBSL) were pursued for 25 years in several Soviet Institutes. Thin single crystal screens of II-VI alloys (ZnxCd1-xSe, CdSxSe1-x) were incorporated in laser CRTs to produce scanned visible laser beams at average powers greater than 10 W. Resolutions of 2500 lines were demonstrated. MDA-W is conducting a program for ARPA/ESTO to assess EBSL technology for high brightness, high resolution RGB laser projection application. Transfer of II-VI crystal growth and screen processing technology is underway, and initial results will be reported. Various techniques (cathodoluminescence, one- and two-photon laser pumping, etc.) have been used to assess material quality and screen processing damage. High voltage (75 kV) video electronics were procured in the U.S. to operate test EBSL tubes. Laser performance was documented as a function of screen temperature, beam voltage and current. The beam divergence, spectrum, efficiency and other characteristics of the laser output are being measured. An evaluation of the effect of laser operating conditions upon the degradation rate is being carried out by a design-of-experiments method. An initial assessment of the projected image quality will be performed.

Design of the extraction arc for the 2nd beam line of the free-electron laser FLASH

International Nuclear Information System (INIS)

Scholz, Matthias

2014-01-01

In this thesis, I deal with the design of the extraction arc for the second beam line of FLASH, an FEL (Free-Electron Laser) user facility at DESY Hamburg. Both beam lines will use the same linear accelerator and their separation will take place behind the last accelerating module. I present the constraints for the extraction arc given by the beam line layout of the existing machine, by the building environment of the new beam line and in particular, by coherent synchrotron radiation (CSR). The impact from CSR is presented, and I show how to mitigate these effects and what that means for the beam line design. The optimization of the extraction arc was done applying the downhill simplex algorithm which is presented, first in its basic form to explain the operation principle and then in a more advanced version as used in the applied program. I introduce in this thesis the final layout of the extraction arc including the following matching section. This layout fulfills all given constraints and can provide the required electron beam quality for FEL operation. In order to prove this, I present start-to-end simulations for different bunch charges and for two different wavelengths.

Laser-Compton Scattering as a Potential Electron Beam Monitor

International Nuclear Information System (INIS)

Chouffani, K.; Wells, D.; Harmon, F.; Lancaster, G.; Jones, J.

2002-01-01

LCS experiments were carried out at the Idaho Accelerator Center (IAC); sharp monochromatic x-ray lines were observed. These are produced using the so-called inverse Compton effect, whereby optical laser photons are collided with a relativistic electron beam. The back-scattered photons are then kinematically boosted to keV x-ray energies. We have first demonstrated these beams using a 20 MeV electron beam collided with a 100 MW, 7 ns Nd; YAG laser. We observed narrow LCS x-ray spectral peaks resulting from the interaction of the electron beam with the Nd; YAG laser second harmonic (532 nm). The LCS x-ray energy lines and energy deviations were measured as a function of the electron beam energy and energy-spread respectively. The results showed good agreement with the predicted valves. LCS could provide an excellent probe of electron beam energy, energy spread, transverse and longitudinal distribution and direction

Status of the ELIMED multidisciplinary and medical beam-line at ELI-Beamlines

International Nuclear Information System (INIS)

Romano, F; Cirrone, G A P; Cuttone, G; Schillaci, F; Scuderi, V; Amico, A; Candiano, G; Larosa, G; Leanza, R; Manna, R; Marchese, V; Milluzzo, G; Petringa, G; Pipek, J; Giordanengo, S; Guarachi, L F; Marchetto, F; Sacchi, R; Korn, G; Margarone, D

2017-01-01

Nowadays, one of the biggest challenges consists in using high intensity laser-target interaction to generate high-energy ions for medical purposes, eventually replacing the old paradigm of acceleration characterized by huge and complex machines. In order to investigate the feasibility of using laser-driven ion beams for multidisciplinary application, a dedicated beam transport line will be installed at the ELI-Beamlines facility in Prague (CZ), as a part of the User-oriented ELIMAIA beam-line dedicated to ion acceleration and their potential applications. The beam-line section dedicated to transport and dosimetric endpoints is called ELIMED (ELI-Beamlines MEDical and multidisciplinary applications) and will be developed by the INFN-LNS. (paper)

First Beam Test of Nanometer Spot Size Monitor Using Laser Interferometry

CERN Document Server

Walz, D

2003-01-01

The nanometer spot size monitor based on the laser interferometry (Laser-Compton Spot Size Monitor) has been tested in FFTB beam line at SLAC. A low emittance beam of 46 GeV electrons, provided by the two-mile linear accelerator, was focused into nanometer spot in the FFTB line, and its transverse dimensions were precisely measured by the spot size monitor.

First Beam Test of Nanometer Spot Size Monitor Using Laser Interferometry

International Nuclear Information System (INIS)

Walz, Dieter R

2003-01-01

The nanometer spot size monitor based on the laser interferometry (Laser-Compton Spot Size Monitor) has been tested in FFTB beam line at SLAC. A low emittance beam of 46 GeV electrons, provided by the two-mile linear accelerator, was focused into nanometer spot in the FFTB line, and its transverse dimensions were precisely measured by the spot size monitor

Beam propagation considerations in the Aurora laser system

International Nuclear Information System (INIS)

Rosoche, L.A.; Mc Leod, J.; Hanlon, J.A.

1987-01-01

Aurora is a high-power KrF laser system now being constructed for inertial confinement fusion (ICF) studies. It will use optical angular multiplexing and serial amplification by electron-beam-driven KrF amplifiers to deliver a stacked, multikilojoule 5-ns-duration laser pulse to ICF targets. The requirements of angular multiplexing KrF lasers at the multikilojoule level dictate path lengths on the order of 1 km. The inherent complicated path crossings produced by angular multiplexing and pulse stacking do not allow isolation of individual beam lines, so the optical quality of the long beam paths must be controlled. Propagation of the 248-nm light beams over long paths in air is affected by scattering, absorption thermal gradients and turbulence, beam alignment, and control and optical component figure errors

New development of hadron physics at new laser electron beam line (LEP2) of SPring-8

International Nuclear Information System (INIS)

Muramatsu, Norihito; Niiyama, Masayuki; Yosoi, Masaru

2015-01-01

This paper introduces the outline of LEPS2 beam line and two types of large detectors (electromagnetic calorimeter BGOegg and solenoid spectrometer), LEPS2/BGOegg experiment, and the target physics using LEPS2 solenoid spectrometer. In LEPS2 beam line, experiments are performed with the improvement of beam intensity by nearly one digit due to the simultaneous incidence of multiple lasers of high output, as well as with the installation of a large solid angle high-resolution detector. In LEPS2/BGOegg experiment, direct observation with a large solid angle of mesons such as π 0 , η, η', and ω has become possible, which has given expectation for new physics. As one of the physics at the core of BGOegg experiments, there is the systematic examination of interaction between η' and nucleus/nucleon. In the physics using a solenoid spectrometer, the first target is the measurement of penta-quark particle Θ + . (A.O.)

Laser stripping of the TRIUMF H- beam

International Nuclear Information System (INIS)

Lee, R.T.; Fraser, J.S.; Levy, C.D.P.

1989-03-01

A ≤ nA external beam of 50 to 200 MeV is required for certain physics and medical experiments at the same time as 200 μA is being accelerated for meson production. A mode-locked laser, synchronized with the cyclotron rf, can produce a 20 nA parasitic H 0 beam for continuous extraction. The best available Nd:YAG or Nd:YLF laser (Av. Pwr. 15 W) mode-locked at a harmonic of the cyclotron rf falls short of the required intensity by a factor of about 50. An optical delay line could trap the mode-locked pulse train to achieve the required intensity. The optical delay line is a near-concentric resonator installed half above and half below the beam plane and in which all trapped pulses cross the midplane in synchronism with the cyclotron beam bunches. An analysis of the delay line is presented in terms of the transfer matrix for one round trip in the periodic focusing system formed by the end mirrors of the resonator. An enhancement factor ≥55 is possible with 80 trapped pulses if the mirror reflectively ≥ 99%

Improvements of high-power diode laser line generators open up new application fields

Science.gov (United States)

Meinschien, J.; Bayer, A.; Bruns, P.; Aschke, L.; Lissotschenko, V. N.

2009-02-01

Beam shaping improvements of line generators based on high power diode lasers lead to new application fields as hardening, annealing or cutting of various materials. Of special interest is the laser treatment of silicon. An overview of the wide variety of applications is presented with special emphasis of the relevance of unique laser beam parameters like power density and beam uniformity. Complementary to vision application and plastic processing, these new application markets become more and more important and can now be addressed by high power diode laser line generators. Herewith, a family of high power diode laser line generators is presented that covers this wide spectrum of application fields with very different requirements, including new applications as cutting of silicon or glass, as well as the beam shaping concepts behind it. A laser that generates a 5m long and 4mm wide homogeneous laser line is shown with peak intensities of 0.2W/cm2 for inspection of railway catenaries as well as a laser that generates a homogeneous intensity distribution of 60mm x 2mm size with peak intensities of 225W/cm2 for plastic processing. For the annealing of silicon surfaces, a laser was designed that generates an extraordinary uniform intensity distribution with residual inhomogeneities (contrast ratio) of less than 3% over a line length of 11mm and peak intensities of up to 75kW/cm2. Ultimately, a laser line is shown with a peak intensity of 250kW/cm2 used for cutting applications. Results of various application tests performed with the above mentioned lasers are discussed, particularly the surface treatment of silicon and the cutting of glass.

Comparison between measurements of hyperfine structures of Pr II - lines investigated by collinear laser ion beam spectroscopy (CLIBS) ans saturation spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Akhtar, Nadeem; Anjum, Naveed [Inst. f. Experimentalphysik, Techn. Univ. Graz, Petersgasse 16, A-8010 Graz (Austria); Optics Labs, Nilore, Islamabad (Pakistan); Huehnermann, Harry [Inst. f. Experimentalphysik, Techn. Univ. Graz, Petersgasse 16, A-8010 Graz (Austria); Fachbereich Physik, Univ. Marburg/Lahn (Germany); Windholz, Laurentius [Inst. f. Experimentalphysik, Techn. Univ. Graz, Petersgasse 16, A-8010 Graz (Austria)

2011-07-01

Investigation of narrow hyperfine structures needs a reduction of the Doppler broadening of the investigated lines. Here we have used two methods: collinear laser spectroscopy (CLIBS) and laser saturation spectroscopy. In the first method, the Doppler width is reduced by accelerating Pr ions to a high velocity and excitation with a collinear laser beam, while in the second method ions with velocity group zero are selected by nonlinear saturation. In this work the hyperfine spectra of several Pr II lines were investigated using CLIBS. A line width of ca. 60 MHz was measured. The same lines were then investigated in a hollow cathode discharge lamp using intermodulated laser-induced fluorescence spectroscopy. Using this technique a spectral line width of about 200 MHz was achieved. In both methods, the excitation source is a ring dye laser operated with R6G. Using a fit program, magnetic dipole interaction constants A and the electric-quadrupole interaction constants B of the involved levels have been determined in both cases. We discuss advantages and disadvantages of both methods.

Laser spectroscopy of relativistic beams of H- and H

International Nuclear Information System (INIS)

Smith, W.W.; Tang, C.Y.; Harris, P.G.; Mohagheghi, A.H.; Bryant, H.C.; Reeder, R.A.; Toutounchi, H.; Sharifian, H.

1989-01-01

Laser spectroscopy on near-light velocity H- ions and H atoms has been carried out at the Los Alamos Meson Physics Facility using a variety of fixed frequency lasers intersecting accelerated beams at variable angles. Beam energies up to 800 MeV (v/c) = 0.84 make possible an unusually wide tuning range at modestly high resolution. A dedicated beam line, the High Resolution Atomic Beam (HIRAB), also makes possible Stark effect and field ionization studies in the multi-megavolt/cm range. Preliminary results on multiphoton detachment of fast H-ions using a pulsed CO 2 laser focussed to ∼10 11 W/cm 2 over a factor 10 photon energy range (CM frame) are presented in this paper

Automatic laser beam position control on the Isolde-Rilis experiment

CERN Document Server

Grancharova, D; Fedosseev, V; Suberlucq, Guy; CERN. Geneva. AB Department

2003-01-01

The On-Line Isotope Mass Separator ISOLDE at CERN is a facility for production of radioactive ion beams by the interaction of proton beams with a thick target. One of the most widely used types of ion source at ISOLDE is a chemically selective laser ion source based on the method of laser ionization of atoms in a hot cavity - RILIS (Resonance Ionization Laser Ion Source). The optical set-up of RILIS includes three copper vapour lasers, a set of dye lasers and frequency multiplication crystals giving up to three different beams of tuneable wavelengths. This paper will focus on the transport of the laser beams to the targets at distances of 18 m and 23 m, the development of the acquisition of their position and finally the automatic control of optics for an accurate alignment.

Beam Line Design and Beam Physics Study of Energy Recovery Linac Free Electron Laser at Peking University

International Nuclear Information System (INIS)

Wang, Guimei

2011-01-01

Energy recovering linac (ERL) offers an attractive alternative for generating intense beams of charged particles by approaching the operational efficiency of a storage ring while maintaining the superior beam quality typical of a linear accelerator. In ERLs, the decelerated beam cancels the beam loading effects of the accelerated beam with high repetition rate. Therefore, ERLs can, in principle, accelerate very high average currents with only modest amounts of RF power. So the efficiency of RF power to beam is much higher. Furthermore, the energy of beam to dump is lower, so it will reduce dump radiation. With the successful experiments in large maximum-to-injection energy ratio up to 51:1 and high power FEL up to 14kW, the use of ERL, especially combining with superconducting RF technology, provides a potentially powerful new paradigm for generation of the charged particle beams used in MW FEL, synchrotron radiation sources, high-energy electron cooling devices and so on. The 3+1/2 DC-SC photo injector and two 9cell TESLA superconducting cavity for IR SASE FEL in PKU provides a good platform to achieve high average FEL with Energy Recovery. The work of this thesis is on Beam line design and Beam dynamics study of Energy Recovery Linac Free Electron Laser for Peking University. It is the upgrade of PKU facility, which is under construction. With ERL, this facility can work in CW mode, so it can operate high average beam current without RF power constraint in main linac and generate high average FEL power. Moreover, it provides a test facility to study the key technology in ERL. System parameters are optimized for PKU ERL-FEL. The oscillation FEL output power is studied with different bunch charge, transverse emittance, bunch length and energy spread. The theory of optimal RF power and Q ext with ERL and without ERL is analyzed and applied to PKU injector and linac including microphonic effect. pace charge effect in the injector and merger is studied for beam energy

Beam Line Design and Beam Physics Study of Energy Recovery Linac Free Electron Laser at Peking University

Energy Technology Data Exchange (ETDEWEB)

Wang, Guimei [Peking Univ., Beijing (China)

2011-12-31

Energy recovering linac (ERL) offers an attractive alternative for generating intense beams of charged particles by approaching the operational efficiency of a storage ring while maintaining the superior beam quality typical of a linear accelerator. In ERLs, the decelerated beam cancels the beam loading effects of the accelerated beam with high repetition rate. Therefore, ERLs can, in principle, accelerate very high average currents with only modest amounts of RF power. So the efficiency of RF power to beam is much higher. Furthermore, the energy of beam to dump is lower, so it will reduce dump radiation. With the successful experiments in large maximum-to-injection energy ratio up to 51:1 and high power FEL up to 14kW, the use of ERL, especially combining with superconducting RF technology, provides a potentially powerful new paradigm for generation of the charged particle beams used in MW FEL, synchrotron radiation sources, high-energy electron cooling devices and so on. The 3+1/2 DC-SC photo injector and two 9cell TESLA superconducting cavity for IR SASE FEL in PKU provides a good platform to achieve high average FEL with Energy Recovery. The work of this thesis is on Beam line design and Beam dynamics study of Energy Recovery Linac Free Electron Laser for Peking University. It is the upgrade of PKU facility, which is under construction. With ERL, this facility can work in CW mode, so it can operate high average beam current without RF power constraint in main linac and generate high average FEL power. Moreover, it provides a test facility to study the key technology in ERL. System parameters are optimized for PKU ERL-FEL. The oscillation FEL output power is studied with different bunch charge, transverse emittance, bunch length and energy spread. The theory of optimal RF power and Q{sub ext} with ERL and without ERL is analyzed and applied to PKU injector and linac including microphonic effect. pace charge effect in the injector and merger is studied for beam

Development of an energy selector system for laser-driven proton beam applications

Energy Technology Data Exchange (ETDEWEB)

Scuderi, V., E-mail: scuderiv@lns.infn.it [Department of Experimental Program at ELI-Beamlines, Institute of Physics of the ASCR, ELI-Beamlines project, Na Slovance 2, Prague (Czech Republic); Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania (Italy); Bijan Jia, S. [Ferdowsi University of Mashhad, Azadi Square, Mashhad (Iran, Islamic Republic of); Carpinelli, M. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania (Italy); Cirrone, G.A.P. [Department of Experimental Program at ELI-Beamlines, Institute of Physics of the ASCR, ELI-Beamlines project, Na Slovance 2, Prague (Czech Republic); Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania (Italy); Cuttone, G. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania (Italy); Korn, G. [Department of Experimental Program at ELI-Beamlines, Institute of Physics of the ASCR, ELI-Beamlines project, Na Slovance 2, Prague (Czech Republic); Licciardello, T. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania (Italy); Maggiore, M. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, Viale dell' Universit 2, Legnaro (Pd) (Italy); Margarone, D. [Department of Experimental Program at ELI-Beamlines, Institute of Physics of the ASCR, ELI-Beamlines project, Na Slovance 2, Prague (Czech Republic); Pisciotta, P.; Romano, F. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania (Italy); Schillaci, F. [Department of Experimental Program at ELI-Beamlines, Institute of Physics of the ASCR, ELI-Beamlines project, Na Slovance 2, Prague (Czech Republic); Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania (Italy); Stancampiano, C. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania (Italy); and others

2014-03-11

Nowadays, laser-driven proton beams generated by the interaction of high power lasers with solid targets represent a fascinating attraction in the field of the new acceleration techniques. These beams can be potentially accelerated up to hundreds of MeV and, therefore, they can represent a promising opportunity for medical applications. Laser-accelerated proton beams typically show high flux (up to 10{sup 11} particles per bunch), very short temporal profile (ps), broad energy spectra and poor reproducibility. In order to overcome these limitations, these beams have be controlled and transported by means of a proper beam handling system. Furthermore, suitable dosimetric diagnostic systems must be developed and tested. In the framework of the ELIMED project, we started to design a dedicated beam transport line and we have developed a first prototype of a beam line key-element: an Energy Selector System (ESS). It is based on permanent dipoles, capable to control and select in energy laser-accelerated proton beams. Monte Carlo simulations and some preliminary experimental tests have been already performed to characterize the device. A calibration of the ESS system with a conventional proton beam will be performed in September at the LNS in Catania. Moreover, an experimental campaign with laser-driven proton beam at the Centre for Plasma Physics, Queens University in Belfast is already scheduled and will be completed within 2014.

A laser-wire beam-energy and beam-profile monitor at the BNL linac

Energy Technology Data Exchange (ETDEWEB)

Connolly, R.; Degen, C.; DeSanto, L.; Meng, W.; Michnoff, R.; Minty, M.; Nayak, S.

2011-03-28

In 2009 a beam-energy monitor was installed in the high energy beam transport (HEBT) line at the Brookhaven National Lab linac. This device measures the energies of electrons stripped from the 40mA H{sup -} beam by background gas. Electrons are stripped by the 2.0x10{sup -7}torr residual gas at a rate of {approx}1.5x10{sup -8}/cm. Since beam electrons have the same velocities as beam protons, the beam proton energy is deduced by multiplying the electron energy by m{sub p}/m{sub e}=1836. A 183.6MeV H{sup -} beam produces 100keV electrons. In 2010 we installed an optics plates containing a laser and scanning optics to add beam-profile measurement capability via photodetachment. Our 100mJ/pulse, Q-switched laser neutralizes 70% of the beam during its 10ns pulse. This paper describes the upgrades to the detector and gives profile and energy measurements.

Bunching and phase focusing of laser generated proton beams

Energy Technology Data Exchange (ETDEWEB)

Schumacher, Dennis; Hofmann, Ingo; Blazevic, Abel; Deppert, Oliver [GSI Helmholtzzentrum fuer Schwerionenforschung (Germany); Busold, Simon; Roth, Markus; Boine-Frankenheim, Oliver [TU Darmstadt (Germany); Brabetz, Christian [Universitaet Frankfurt, Frankfurt am Main (Germany); Zielbauer, Bernhard [HI Jena (Germany); Collaboration: LIGHT-Collaboration

2013-07-01

Laser accelerated proton beams can reach very high intensities and very low emittances. Therefore they are suitable as ion sources for many applications. One is the coupling into common ion accelerator structures to replace pre accelerators that are used so far. The LIGHT (Laser Ion Generation, Handling and Transport) collaboration has been founded to develop ion optics and targets and optimize laser parameter to make this coupling most efficient. In a first step a short pulse beam line for the PHELIX-laser at GSI to the experiment site Z6 has been build in order to laser accelerate protons here. In a second step a pulsed solenoid has been established to collimate the divergent ion beam. In a third step this collimated beam will be coupled into a bunching unit, which consists of a spiral resonator with three gaps which leads to an overall acceleration voltage of 1 MV. With this cavity it is not only possible to avoid the broadening of the pulse, but also to phase focus it. This talk presents also the progress towards the operation of the spiral resonator as buncher for a laser accelerated ion beam e.g. simulations, tests and performance data and shows the next steps of the beam shaping efforts.

Precision atomic beam density characterization by diode laser absorption spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Oxley, Paul; Wihbey, Joseph [Physics Department, The College of the Holy Cross, Worcester, Massachusetts 01610 (United States)

2016-09-15

We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10{sup −5} are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10{sup 4} atoms cm{sup −3}. The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

Precision atomic beam density characterization by diode laser absorption spectroscopy

International Nuclear Information System (INIS)

Oxley, Paul; Wihbey, Joseph

2016-01-01

We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10 −5 are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10 4 atoms cm −3 . The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

Precision atomic beam density characterization by diode laser absorption spectroscopy.

Science.gov (United States)

Oxley, Paul; Wihbey, Joseph

2016-09-01

We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10 -5 are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10 4 atoms cm -3 . The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

Spatial modification of laser beam under the influence of Λ-type strong pump

International Nuclear Information System (INIS)

Lee, Won Kyu; Noh, Young Chul; Jeon, Jin Ho; Lee, Jai Hyung; Chang, Joon Sung

1999-01-01

The laser beam propagating through the resonant medium undergo severe deformation because of nonlinear interaction such as self-focusing, self-defocusing, etc. When strong pump beam coexists with the probe beam, propagation characteristics can be changed. We use samarium (Sm) vapor as the nonlinear medium. Probe laser is tuned around 4f 6 6s 27 F 0 -> 4f 6 ( 7 F)6s6p( 1 P 0 ) transition line of Sm (561.601 nm) and the pump laser is tuned around 4f 6 6s 27 F 1 -> 4f 6 ( 7 F)6s6p( 1 P 0 ) transition line of Sm (572.019 nm). The probe and the pump beams are Λ-type configuration. The transmission of the probe beam is changed as the intensity and the detuning of the pump beam are varied. The degree of self-focusing is also modified. (author)

The Challenge of Interfacing the Primary Beam Lines for the AWAKE Project at CERN

CERN Document Server

Bracco, C; Gschwendtner, E; Meddahi, M; Petrenko, A; Velotti, FM

2014-01-01

The Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) at CERN foresees the simultaneous operation of a proton, a laser and an electron beam. The first stage of the experiment will consist in proving the self-modulation, in the plasma, of a long proton bunch into micro-bunches. The success of this experiment requires an almost perfect concentricity of the proton and laser beam, over the full length of the plasma cell. The complexity of integrating the laser into the proton beam line and fulfilling the strict requirements in terms of pointing precision of the proton beam at the plasma cell are described. The second stage of the experiment foresees also the injection of electron bunches to probe the accelerating wakefields driven by the proton beam. Studies were performed to evaluate the possibility of injecting the electron beam parallel and with an offset to the beam axis. This option would imply that protons and electrons will have to share the last few meters of a common beam line. Issues and po...

High resolution laser spectroscopy as a diagnostic tool in beams

International Nuclear Information System (INIS)

Bergmann, K.; Hefter, U.; Hering, P.

1977-01-01

The combination of high resolution laser spectroscopy with the technique of molecular beams allows a very detailed beam research since molecules or atoms in specific quantum states can be sampled yielding previously unavailable sources of data. In these experiments a Na/Na 2 beam emerges from a 0.2 mm nozzle and is collimated by a 2 mm wide slit 50 cm downstream. To probe the molecules a single mode Ar + -laser was used which can be tuned within the gain profile of the laser line (8 GHz) to several transitions between specific levels in the ground state and second electronically excited state of the Na 2 molecule. (Auth.)

Laser Beam Focus Analyser

DEFF Research Database (Denmark)

Nielsen, Peter Carøe; Hansen, Hans Nørgaard; Olsen, Flemming Ove

2007-01-01

the obtainable features in direct laser machining as well as heat affected zones in welding processes. This paper describes the development of a measuring unit capable of analysing beam shape and diameter of lasers to be used in manufacturing processes. The analyser is based on the principle of a rotating......The quantitative and qualitative description of laser beam characteristics is important for process implementation and optimisation. In particular, a need for quantitative characterisation of beam diameter was identified when using fibre lasers for micro manufacturing. Here the beam diameter limits...... mechanical wire being swept through the laser beam at varying Z-heights. The reflected signal is analysed and the resulting beam profile determined. The development comprised the design of a flexible fixture capable of providing both rotation and Z-axis movement, control software including data capture...

Short distance line of sight laser communication

International Nuclear Information System (INIS)

Mudassar, A.A.; Hussain, H.; Jamil-ur-Rehman

1998-01-01

Communication methods based on lasers as carrier are well known. In our work we have made a two way laser based communication system for short range (<2 Km) line of sight communication. A small piece of plane mirror (100% reflector) was mounted on the centre of a speaker cone. The speaker was positioned close to the opening of laser such that He-Ne laser beam (10 mW) after reflection from the mirror is directed towards the receiver. There is a pre-amplifier and an amplifier between a microphone and the speaker. When the diagram of the speaker vibrates, it positionally modulates the laser beam. On the receiving end, there is a photo diode, a pre-amplifier, an amplifier and a head phone. So the man on the receiving end can decode the sound signal. On each stage there is a transmitter and a receiver assembled close to each other. So the two way communication is possible in the range 20 to 20 Khz. (author)

Modematic: a fast laser beam analyzing system for high power CO2-laser beams

Science.gov (United States)

Olsen, Flemming O.; Ulrich, Dan

2003-03-01

The performance of an industrial laser is very much depending upon the characteristics of the laser beam. The ISO standards 11146 and 11154 describing test methods for laser beam parameters have been approved. To implement these methods in industry is difficult and especially for the infrared laser sources, such as the CO2-laser, the availabl analyzing systems are slow, difficult to apply and having limited reliability due to the nature of the detection methods. In an EUREKA-project the goal was defined to develop a laser beam analyzing system dedicated to high power CO2-lasers, which could fulfill the demands for an entire analyzing system, automating the time consuming pre-alignment and beam conditioning work required before a beam mode analyses, automating the analyzing sequences and data analysis required to determine the laser beam caustics and last but not least to deliver reliable close to real time data to the operator. The results of this project work will be described in this paper. The research project has led to the development of the Modematic laser beam analyzer, which is ready for the market.

A high intensity beam line of γ-rays up to 22MeV energy based on Compton backscattering

International Nuclear Information System (INIS)

Guo, W.; Xu, W.; Chen, J.G.; Ma, Y.G.; Cai, X.Z.; Wang, H.W.; Xu, Y.; Wang, C.B.; Lu, G.C.; Tian, W.D.; Yuan, R.Y.; Xu, J.Q.; Wei, Z.Y.; Yan, Z.; Shen, W.Q.

2007-01-01

Shanghai Laser Electron Gamma Source, a high intensity beam line of γ-ray, has been proposed recently. The beam line is expected to generate γ-rays up to the maximum energy of 22MeV by Compton backscattering between a CO 2 laser and electrons in the 3.5 GeV storage ring of the Shanghai Synchrotron Radiation Facility. The flux of non-collimated γ-rays is estimated to be 10 9 -10 10 s -1 when a CO 2 laser of several hundred Watt power is employed. We will discuss physics issues in the design and optimization of the beam line

Laser beam diagnostics for kilowatt power pulsed YAG laser

International Nuclear Information System (INIS)

Liu, Yi; Leong, Keng H.

1992-01-01

There is a growing need for high power YAG laser beam diagnostics with the recent introduction of such lasers in laser material processing. In this paper, we will describe the use of a commercially available laser beam analyzer (Prometec) to profile the laser beam from a 1600 W pulsed Nd:YAG laser that has a 1 mm fiber optic beam delivery system. The selection of laser pulse frequency and pulse width for the measurement is discussed. Laser beam propagation parameters by various optical components such as fibers and lenses can be determined from measurements using this device. The importance of such measurements will be discussed

Effects of a laser beam profile on Zeeman electromagnetically induced transparency in the Rb buffer gas cell

International Nuclear Information System (INIS)

Nikolić, S N; Radonjić, M; Krmpot, A J; Lučić, N M; Zlatković, B V; Jelenković, B M

2013-01-01

Electromagnetically induced transparency (EIT) due to Zeeman coherences in the Rb buffer gas cell is studied for different laser beam profiles, laser beam radii and intensities from 0.1 to 10 mW cm −2 . EIT line shapes can be approximated by the Lorentzian for wide Gaussian laser beam (6.5 mm in diameter) if laser intensity is weak and for a Π laser beam profile of the same diameter. Line shapes of EIT become non-Lorentzian for the Gaussian laser beam if it is narrow (1.3 mm in diameter) or if it has a higher intensity. EIT amplitudes and linewidths, for both laser beam profiles of the same diameter, have very similar behaviour regarding laser intensity and Rb cell temperature. EIT amplitudes are maximal at a certain laser beam intensity and this intensity is higher for narrower laser beams. The EIT linewidth estimated at zero laser intensity is about 50 nT or 0.7 kHz, which refers to 1.5 ms relaxation times of Zeeman coherences in 87 Rb atoms in our buffer gas cell. Blocking of the centre of the wide Gaussian laser beam in front of the photo detector yields Lorentzian profiles with a much better contrast to the linewidth ratio for EIT at higher intensities, above ∼2 mW cm −2 . (paper)

Laser beam alignment and profilometry using diagnostic fluorescent safety mirrors

Science.gov (United States)

Lizotte, Todd E.

2011-03-01

There are a wide range of laser beam delivery systems in use for various purposes; including industrial and medical applications. Virtually all such beam delivery systems for practical purposes employ optical systems comprised of mirrors and lenses to shape, focus and guide the laser beam down to the material being processed. The goal of the laser beam delivery is to set the optimum parameters and to "fold" the beam path to reduce the mechanical length of the optical system, thereby allowing a physically compact system. In many cases, even a compact system can incorporate upwards of six mirrors and a comparable number of lenses all needing alignment so they are collinear. One of the major requirements for use of such systems in industry is a method of safe alignment. The alignment process requires that the aligner determine where the beam strikes each element. The aligner should also preferably be able to determine the shape or pattern of the laser beam at that point and its relative power. These alignments are further compounded in that the laser beams generated are not visible to the unaided human eye. Such beams are also often of relatively high power levels, and are thereby a significant hazard to the eyes of the aligner. Obvious an invisible beam makes it nearly impossible to align laser system without some form of optical assistance. The predominant method of visually aligning the laser beam delivery is the use of thermal paper, paper cards or fluorescing card material. The use of paper products which have limited power handling capability or coated plastics can produce significant debris and contaminants within the beam line that ultimately damage the optics. The use of the cards can also create significant laser light scatter jeopardizing the safety of the person aligning the system. This paper covers a new safety mirror design for use with at various UV and Near IR wavelengths (193 nm to 1064 nm) within laser beam delivery systems and how its use can

Distribution uniformity of laser-accelerated proton beams

Science.gov (United States)

Zhu, Jun-Gao; Zhu, Kun; Tao, Li; Xu, Xiao-Han; Lin, Chen; Ma, Wen-Jun; Lu, Hai-Yang; Zhao, Yan-Ying; Lu, Yuan-Rong; Chen, Jia-Er; Yan, Xue-Qing

2017-09-01

Compared with conventional accelerators, laser plasma accelerators can generate high energy ions at a greatly reduced scale, due to their TV/m acceleration gradient. A compact laser plasma accelerator (CLAPA) has been built at the Institute of Heavy Ion Physics at Peking University. It will be used for applied research like biological irradiation, astrophysics simulations, etc. A beamline system with multiple quadrupoles and an analyzing magnet for laser-accelerated ions is proposed here. Since laser-accelerated ion beams have broad energy spectra and large angular divergence, the parameters (beam waist position in the Y direction, beam line layout, drift distance, magnet angles etc.) of the beamline system are carefully designed and optimised to obtain a radially symmetric proton distribution at the irradiation platform. Requirements of energy selection and differences in focusing or defocusing in application systems greatly influence the evolution of proton distributions. With optimal parameters, radially symmetric proton distributions can be achieved and protons with different energy spread within ±5% have similar transverse areas at the experiment target. Supported by National Natural Science Foundation of China (11575011, 61631001) and National Grand Instrument Project (2012YQ030142)

Large area electron beam pumped krypton fluoride laser amplifier

International Nuclear Information System (INIS)

Sethian, J.D.; Obenschain, S.P.; Gerber, K.A.; Pawley, C.J.; Serlin, V.; Sullivan, C.A.; Webster, W.; Deniz, A.V.; Lehecka, T.; McGeoch, M.W.; Altes, R.A.; Corcoran, P.A.; Smith, I.D.; Barr, O.C.

1997-01-01

Nike is a recently completed multi-kilojoule krypton fluoride (KrF) laser that has been built to study the physics of direct drive inertial confinement fusion. This paper describes in detail both the pulsed power and optical performance of the largest amplifier in the Nike laser, the 60 cm amplifier. This is a double pass, double sided, electron beam-pumped system that amplifies the laser beam from an input of 50 J to an output of up to 5 kJ. It has an optical aperture of 60 cm x 60 cm and a gain length of 200 cm. The two electron beams are 60 cm high x 200 cm wide, have a voltage of 640 kV, a current of 540 kA, and a flat top power pulse duration of 250 ns. A 2 kG magnetic field is used to guide the beams and prevent self-pinching. Each electron beam is produced by its own Marx/pulse forming line system. The amplifier has been fully integrated into the Nike system and is used on a daily basis for laser-target experiments. copyright 1997 American Institute of Physics

Implementation and performance of beam smoothing on 10 beams of the Nova Laser

International Nuclear Information System (INIS)

Pennington, D.M.

1997-01-01

Recent simulations and experiments on Nova indicate that some level of smoothing may be required to suppress filamentation in plasmas on the National Ignition Facility (NIF), resulting in the addition of 1-D smoothing capability to the current baseline design. Control of stimulated Brillouin scattering (SBS) and filamentation is considered essential to the success of laser fusion because they affect the amount and location of laser energy delivered to the x-ray conversion region (hohlraum wall) for indirect drive and to the absorptive region for direct drive, Smoothing by spectral dispersion (SSD)[1], reduces these instabilities by reducing nonuniformities in the focal irradiance when averaged over a finite time interval. We have installed SSD on Nova to produce beam smoothing on all 10 beam lines. A single dispersion grating is located in a position common to all 10 beam lines early in the preamplifier chain. This location limits the 1 ω bandwidth to 2.2 (angstrom) with sufficient dispersion to displace the speckle field of each frequency component at the target plane by one half speckle diameter. Several beam lines were modified to allow orientation of the dispersion on each arm relative to the hohlraum wall. After conversion to the third harmonic the beam passes through a kinoform phase plate (KPP) designed to produce an elliptical spot at best focus. The KPPs produce a focal spot having an elliptical flat-top envelope with a superimposed speckle pattern. Over 93% of the energy is contained in the central 400 km. Calculations indicate a 16% rms. intensity variance will be reached after 330 ps for a single beam

Hyperfine Structure of Spectral Lines of 143Nd+, 145Nd+, 139La+, 141Pr+ and 137Ba+ Investigated by Collinear Laser Ion Beam Spectroscopy

International Nuclear Information System (INIS)

Anjum, N.

2012-01-01

In this research work the hyperfine structures of spectral lines of barium (Ba) and three lanthanides elements; praseodymium (Pr), lanthanum (La) and neodymium (Nd) have been investigated. The hyperfine splitting factors A and B of the involved levels have been determined with high accuracy and the data are compared with other published results. This research work is divided in four parts. In the 1st part, the hyperfine structures of the spectral lines of the singly ionized praseodymium (Pr II) are investigated by three different laser spectroscopic techniques; laser induced fluorescence (LIF) spectroscopy, inter-modulated saturation spectroscopy and collinear laser ion beam spectroscopy (CLIBS). The 2nd part is concerned with the a control-check of the Marburg mass separator (MARS-II), as it was shifted from the University of Marburg, Germany, to Graz University of Technology in 2002. The check is performed using a well known spectral line 5853.67 Å of the odd isotope of singly ionized barium (137Ba II). In the 3rd part of this work the hyperfine structure of spectral lines of lanthanum-139 ions (139La II) is investigated. The 4th part is devoted to the investigation of the hyperfine structure of spectral lines of two odd isotopes of singly ionized neodymium (143Nd II and 145Nd II) and the determination of the coupling constants A and B of the involved levels. To determine the hyperfine anomaly the ratios of the magnetic dipole constants, i.e A143/A145, and the electric quadrupole constants B143/B145 of the corresponding levels are also calculated. The last three parts of this research project are executed using the high resolution, Doppler reduced method of CLIBS. In CLIBS technique the ions are accelerated by applying a high potential difference (∼ 20 kV). Due to the accelerating cooling (kinematic compression) the spread in velocities in the direction of the flight is reduced several times, hence the Doppler width is reduced. The accelerated ion beam is mass

A new in-gas-laser ionization and spectroscopy laboratory for off-line studies at KU Leuven

International Nuclear Information System (INIS)

Kudryavtsev, Yu.; Creemers, P.; Ferrer, R.; Granados, C.; Gaffney, L.P.; Huyse, M.; Mogilevskiy, E.; Raeder, S.; Sels, S.; Van den Bergh, P.; Van Duppen, P.; Zadvornaya, A.

2016-01-01

The in-gas laser ionization and spectroscopy (IGLIS) technique is used to produce and to investigate short-lived radioactive isotopes at on-line ion beam facilities. In this technique, the nuclear reaction products recoiling out of a thin target are thermalized and neutralized in a high-pressure noble gas, resonantly ionized by the laser beams in a two-step process, and then extracted from the ion source to be finally accelerated and mass separated. Resonant ionization of radioactive species in the supersonic gas jet ensures very high spectral resolution because of essential reduction of broadening mechanisms. To obtain the maximum efficiency and the best spectral resolution, properties of the supersonic jet and the laser beams must be optimized. To perform these studies a new off-line IGLIS laboratory, including a new high-repetition-rate laser system and a dedicated off-line mass separator, has been commissioned. In this article, the specifications of the different components necessary to achieve optimum conditions in laser-spectroscopy studies of radioactive beams using IGLIS are discussed and the results of simulations are presented.

Numerical analysis of thermal deformation in laser beam heating of a steel plate

Energy Technology Data Exchange (ETDEWEB)

Wang, Chao; Kim, Yong-Rae; Kim, Jae-Woong [Yeungnam University, Kyongsan (Korea, Republic of)

2017-05-15

Line heating is a widely used process for plate forming or thermal straightening. Flame heating and induction heating are the traditional heating processes used by industry for line heating. However, these two heating processes are ineffective when used on small steel plates. Thus, the laser beam heating with various power profiles were carried out in this study. A comparison of numerical simulation results and experimental results found a significant difference in the thermal deformation when apply a different power profile of laser beam heating. The one-sinusoid power profile produced largest thermal deformation in this study. The laser beam heating process was simulated by established a combined heat source model, and simulated results were compared with experimental results to confirm the model’s accuracy. The mechanism of thermal deformation was investigated and the effects of model parameters were studied intensively with the finite element method. Thermal deformation was found to have a significant relationship with the amount of central zone plastic deformation. Scientists and engineers could use this study’s verified model to select appropriate parameters in laser beam heating process. Moreover, by using the developed laser beam model, the analysis of welding residual stress or hardness could also be investigated from a power profile point of view.

Compression of Ultrafast Laser Beams

Science.gov (United States)

2016-03-01

Copyright 2003, AIP Publishing LLC. DOI: http://dx.doi.org/10.1063/1.1611998.) When designing the pulse shaper, the laser beam must completely fill the...for the design of future versions of this device. The easiest way to align the pulse shaper is to use the laser beam that will be shaped, without...Afterward, an ultrafast thin beam splitter is placed into the system after the diameter of the laser beam is reduced; this is done to monitor the beam

ELIMED, future hadrontherapy applications of laser-accelerated beams

International Nuclear Information System (INIS)

Cirrone, Giuseppe A.P.; Carpinelli, Massimo; Cuttone, Giacomo; Gammino, Santo; Bijan Jia, S.; Korn, Georg; Maggiore, Mario; Manti, Lorenzo; Margarone, Daniele; Prokupek, Jan; Renis, Marcella; Romano, Francesco; Schillaci, Francesco; Tomasello, Barbara; Torrisi, Lorenzo; Tramontana, Antonella; Velyhan, Andriy

2013-01-01

Laser-ion acceleration has recently gained a great interest as an alternative to conventional and more expensive acceleration techniques. These ion beams have desirable qualities such as small source size, high luminosity and small emittance to be used in different fields as Nuclear Physics, Medical Physics, etc. This is very promising specially for the future perspective of a new concept of hadrontherapy based on laser-based devices could be developed, replacing traditional accelerating machines. Before delivering laser-driven beams for treatments they have to be handled, cleaned from unwanted particles and characterized in order to have the clinical requirements. In fact ion energy spectra have exponential trend, almost 100% energy spread and a wide angular divergence which is the biggest issue in the beam transport and, hence, in a wider use of this technology. In order to demonstrate the clinical applicability of laser-driven beams new collaboration between ELI-Beamlines project researchers from Prague (Cz) and a INFN-LNS group from Catania (I) has been already launched and scientists from different countries have already express their will in joining the project. This cooperation has been named ELIMED (MEDical application at ELIBeamlines) and will take place inside the ELI-Beamlines infrastructure located in Prague. This work describes the schedule of the ELIMED project and the design of the energy selector which will be realized at INFN-LNS. The device is an important part of the whole transport beam line which will be realised in order to make the ion beams suitable for medical applications. -- Highlights: •We simulated the energy selection system, in order to optimize the device. •We simulated the experimental setup for the run at the TARANIS laser system. •We studied the efficiency of the devise for a proton beam with an uniform energy spectrum

ELIMED, future hadrontherapy applications of laser-accelerated beams

Energy Technology Data Exchange (ETDEWEB)

Cirrone, Giuseppe A.P. [INFN-LNS, Catania (Italy); Institute of Physics of the ASCR, ELI-Beamlines Project, Prague (Czech Republic); Carpinelli, Massimo [INFN Sezione di Caglari, c/o Dipartimento di Fisica, Università di Cagliari, Cagliari (Italy); Cuttone, Giacomo; Gammino, Santo [INFN-LNS, Catania (Italy); Bijan Jia, S. [Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Korn, Georg [Institute of Physics of the ASCR, ELI-Beamlines Project, Prague (Czech Republic); Maggiore, Mario [Institute of Physics of the ASCR, ELI-Beamlines Project, Prague (Czech Republic); INFN-LNL, Legnaro (Italy); Manti, Lorenzo [University Federico II of Naples, Dip.to di Scienze Fisiche, Naples (Italy); Margarone, Daniele; Prokupek, Jan [Institute of Physics of the ASCR, ELI-Beamlines Project, Prague (Czech Republic); Renis, Marcella [University of Catania, Catania (Italy); Romano, Francesco [INFN-LNS, Catania (Italy); Centro Studi e Ricerche “E. Fermi”, Roma (Italy); Schillaci, Francesco, E-mail: francesco.schillaci@eli-beams.eu [INFN-LNS, Catania (Italy); Institute of Physics of the ASCR, ELI-Beamlines Project, Prague (Czech Republic); Tomasello, Barbara [University of Catania, Catania (Italy); Torrisi, Lorenzo [INFN-LNS, Catania (Italy); Dip. to di Fisica, University of Messina, Messina (Italy); Tramontana, Antonella [INFN-LNS, Catania (Italy); Velyhan, Andriy [Institute of Physics of the ASCR, ELI-Beamlines Project, Prague (Czech Republic)

2013-12-01

Laser-ion acceleration has recently gained a great interest as an alternative to conventional and more expensive acceleration techniques. These ion beams have desirable qualities such as small source size, high luminosity and small emittance to be used in different fields as Nuclear Physics, Medical Physics, etc. This is very promising specially for the future perspective of a new concept of hadrontherapy based on laser-based devices could be developed, replacing traditional accelerating machines. Before delivering laser-driven beams for treatments they have to be handled, cleaned from unwanted particles and characterized in order to have the clinical requirements. In fact ion energy spectra have exponential trend, almost 100% energy spread and a wide angular divergence which is the biggest issue in the beam transport and, hence, in a wider use of this technology. In order to demonstrate the clinical applicability of laser-driven beams new collaboration between ELI-Beamlines project researchers from Prague (Cz) and a INFN-LNS group from Catania (I) has been already launched and scientists from different countries have already express their will in joining the project. This cooperation has been named ELIMED (MEDical application at ELIBeamlines) and will take place inside the ELI-Beamlines infrastructure located in Prague. This work describes the schedule of the ELIMED project and the design of the energy selector which will be realized at INFN-LNS. The device is an important part of the whole transport beam line which will be realised in order to make the ion beams suitable for medical applications. -- Highlights: •We simulated the energy selection system, in order to optimize the device. •We simulated the experimental setup for the run at the TARANIS laser system. •We studied the efficiency of the devise for a proton beam with an uniform energy spectrum.

Laser spectroscopy in an lithium beam

International Nuclear Information System (INIS)

Duarte, A.; Sylvester, G.; Olivares, I.E.

1998-01-01

Full text: The absorption and fluorescence spectra were measured in a collimated and non-collimated atomic lithium beam by means of a diode laser. Spectral lines with a similar linewidth as the lines observed before in a stationary lithium vapor were observed in the non-collimated beam. The spatial structure of the gas region which emits fluorescence permits to observe in situ the hyperfine levels of lithium atoms: each level corresponds to a relatively plane and well defined region. This indicates that the atoms leave the oven following straight lines (otherwise the collisions would produce diffuse regions), which is in correspondence to the high values of the free mean path expected for the gas at this density, and the extension of the shadow left at the condensation plate. In the collimated beam (diameter D=1 mm, and divergence of 90 mrad), the absorption spectra has a width of 450 MHz (12 deg K or less), which permits the measurement of the hyperfine structure. In this case, from the absorption data we obtained ρD=2 x 10 14 atoms/m 2 . The temperature obtained from the Doppler width is consistent with the temperature obtained from the beam geometry. The lithium atom flow was measured with a quartz thickness monitor and based on estimates of the initial oven temperature and density measurements. Fluorescence measurements have better sensitivity ab do not present problems in the base line due to etalon effects. It is possible to observe the detail structure of the side wings in the line spectra

M2 qualify laser beam propagation

International Nuclear Information System (INIS)

Abdelhalim, Bencheikh; Mohamed, Bouafia

2010-01-01

One of the most important properties of a laser resonator is the highly collimated or spatially coherent nature of the laser output beam. Laser beam diameter and quality factor M 2 are significant parameters in a wide range of laser applications. This is because the spatial beam quality determines how closely the beam can be focused or how well the beam propagates over long distances without significant dispersion. In the present paper we have used three different methods to qualify the spatial structure of a laser beam propagating in free space, the results are obtained and discussed, and we have found that the Wigner distribution function is a powerful tool which allows a global characterization of any kind of beam

Coherent laser beam combining

CERN Document Server

Brignon, Arnaud

2013-01-01

Recently, the improvement of diode pumping in solid state lasers and the development of double clad fiber lasers have allowed to maintain excellent laser beam quality with single mode fibers. However, the fiber output power if often limited below a power damage threshold. Coherent laser beam combining (CLBC) brings a solution to these limitations by identifying the most efficient architectures and allowing for excellent spectral and spatial quality. This knowledge will become critical for the design of the next generation high-power lasers and is of major interest to many industrial, environme

Electron-beam-excited gas laser research

International Nuclear Information System (INIS)

Johnson, A.W.; Gerardo, J.B.; Patterson, E.L.; Gerber, R.A.; Rice, J.K.; Bingham, F.W.

1975-01-01

Net energy gain in laser fusion places requirements on the laser that are not realized by any existing laser. Utilization of relativistic electron beams (REB's), a relatively new source for the excitation of gas laser media, may lead to new lasers that could satisfy these requirements. Already REB's have been utilized to excite gas laser media and produce gas lasers that have not been produced as successfully any other way. Electron-beam-excitation has produced electronic-transition dimer lasers that have not yet been produced by any other excitation scheme (for example, Xe 2 / sup *(1)/, Kr:O(2 1 S)/sup 2/, KrF/sup *(3)/). In addition, REB's have initiated chemical reactions to produce HF laser radiation with unique and promising results. Relativistic-electron-beam gas-laser research is continuing to lead to new lasers with unique properties. Results of work carried out at Sandia Laboratories in this pioneering effort of electron-beam-excited-gas lasers are reviewed. (U.S.)

Efficient sub-Doppler transverse laser cooling of an indium atomic beam

International Nuclear Information System (INIS)

Kim, Jae-Ihn

2009-01-01

Laser cooled atomic gases and atomic beams are widely studied samples in experimental research in atomic and optical physics. For the application of ultra cold gases as model systems for e.g. quantum many particle systems, the atomic species is not very important. Thus this field is dominated by alkaline, earthalkaline elements which are easily accessible with conventional laser sources and have convenient closed cooling transition. On the other hand, laser cooled atoms may also be interesting for technological applications, for instance for the creation of novel materials by atomic nanofabrication (ANF). There it will be important to use technologically relevant materials. As an example, using group III atoms of the periodical table in ANF may open a route to generate fully 3D structured composite materials. The minimal requirement in such an ANF experiment is the collimation of an atomic beam which is accessible by one dimensional laser cooling. In this dissertation, I describe transverse laser cooling of an Indium atomic beam. For efficient laser cooling on a cycling transition, I have built a tunable, continuous-wave coherent ultraviolet source at 326 nm based on frequency tripling. For this purpose, two independent high power Yb-doped fiber amplifiers for the generation of the fundamental radiation at λ ω = 977 nm have been constructed. I have observed sub-Doppler transverse laser cooling of an Indium atomic beam on a cycling transition of In by introducing a polarization gradient in the linear-perpendicular-linear configuration. The transverse velocity spread of a laser-cooled In atomic beam at full width at half maximum was achieved to be 13.5±3.8 cm/s yielding a full divergence of only 0.48 ± 0.13 mrad. In addition, nonlinear spectroscopy of a 3-level, Λ-type level system driven by a pump and a probe beam has been investigated in order to understand the absorption line shapes used as a frequency reference in a previous two-color spectroscopy experiment

Efficient sub-Doppler transverse laser cooling of an indium atomic beam

Energy Technology Data Exchange (ETDEWEB)

Kim, Jae-Ihn

2009-07-23

Laser cooled atomic gases and atomic beams are widely studied samples in experimental research in atomic and optical physics. For the application of ultra cold gases as model systems for e.g. quantum many particle systems, the atomic species is not very important. Thus this field is dominated by alkaline, earthalkaline elements which are easily accessible with conventional laser sources and have convenient closed cooling transition. On the other hand, laser cooled atoms may also be interesting for technological applications, for instance for the creation of novel materials by atomic nanofabrication (ANF). There it will be important to use technologically relevant materials. As an example, using group III atoms of the periodical table in ANF may open a route to generate fully 3D structured composite materials. The minimal requirement in such an ANF experiment is the collimation of an atomic beam which is accessible by one dimensional laser cooling. In this dissertation, I describe transverse laser cooling of an Indium atomic beam. For efficient laser cooling on a cycling transition, I have built a tunable, continuous-wave coherent ultraviolet source at 326 nm based on frequency tripling. For this purpose, two independent high power Yb-doped fiber amplifiers for the generation of the fundamental radiation at {lambda}{sub {omega}} = 977 nm have been constructed. I have observed sub-Doppler transverse laser cooling of an Indium atomic beam on a cycling transition of In by introducing a polarization gradient in the linear-perpendicular-linear configuration. The transverse velocity spread of a laser-cooled In atomic beam at full width at half maximum was achieved to be 13.5{+-}3.8 cm/s yielding a full divergence of only 0.48 {+-} 0.13 mrad. In addition, nonlinear spectroscopy of a 3-level, {lambda}-type level system driven by a pump and a probe beam has been investigated in order to understand the absorption line shapes used as a frequency reference in a previous two

Laser beam-forming by deformable mirror for laser isotope separation

International Nuclear Information System (INIS)

Nemoto, Koshichi; Fujii, Takashi; Goto, Naohiko

1995-01-01

A rectangular laser beam of uniform intensity is very suitable for laser isotope separation. In this paper, we propose a beam-forming system which consists two deformable mirrors. One of the mirrors changes the beam intensity and the other compensates for phase distortion. We developed a deformable mirror for beam-forming. Its deformed surface is similar to the ideal mirror surface for beam-forming. We reshaped a Gaussian-like He-Ne laser beam into a beam with a more uniform intensity profile by a simple deformable mirror. (author)

TOF technique for laser-driven proton beam diagnostics for the ELIMED beamline

International Nuclear Information System (INIS)

Milluzzo, G.; Scuderi, V.; Amico, A.G.; Cirrone, G.A.P.; Cuttone, G.; Larosa, G.; Leanza, R.; Petringa, G.; Pipek, J.; Romano, F.; Napoli, M. De; Dostal, J.; Margarone, D.; Schillaci, F.; Velyhan, A.

2017-01-01

The Time of Flight (TOF) method for laser-driven ion beam diagnostics has been extensively investigated so far for low energy ion diagnostics and several works, reported in literature [1,2], have shown its efficiency in the measurement of particle beam characteristics such as ion species, energy spectrum and current. Moreover, such technique allows obtaining a shot-to-shot on-line monitoring of optically accelerated particles, necessary to control the reproducibility of the accelerated beam and to deliver a beam suitable for any kind of applications. For this reason, the ELIMED beamline [3,4], which will be entirely developed at INFN-LNS and installed in 2017 within the ion beamline ELIMAIA (ELI Multidisciplinary Applications of laser-Ion Acceleration) experimental hall at ELI-Beamlines in Prague, will be equipped with an on-line diagnostics system composed by silicon carbide and diamond detectors, using the TOF technique. In this contribution, the procedure developed for TOF signal analysis will be briefly reported.

A specialized bioengineering ion beam line

International Nuclear Information System (INIS)

Yu, L.D.; Sangyuenyongpipat, S.; Sriprom, C.; Thongleurm, C.; Suwanksum, R.; Tondee, N.; Prakrajang, K.; Vilaithong, T.; Brown, I.G.; Wiedemann, H.

2007-01-01

A specialized bioengineering ion beam line has recently been completed at Chiang Mai University to meet rapidly growing needs of research and application development in low-energy ion beam biotechnology. This beam line possesses special features: vertical main beam line, low-energy (30 keV) ion beams, double swerve of the beam, a fast pumped target chamber, and an in-situ atomic force microscope (AFM) system chamber. The whole beam line is situated in a bioclean environment, occupying two stories. The quality of the ion beam has been studied. It has proved that this beam line has significantly contributed to our research work on low-energy ion beam biotechnology

Beam Optics for Typical Part of ISOL Beam Lines

International Nuclear Information System (INIS)

Jang, Ji Ho; Kwon, Hyeok Jung; Kim, Han Sung; Cho, Yong Sub

2013-01-01

KOMAC (Korea Multi-purpose Accelerator Complex) is doing a project, the detailed design of the ISOL beam lines for the heavy ion accelerator project of IBS (Institute of Basic Science) from August 2013 to February 2014. The heavy ion beams are transported by using the electrostatic quadrupoles and electrostatic benders between the equipment. The work-scope of the project is the beam optics design of the beam lines and the detailed design of the beam optics components, the electrostatic quadrupoles and the electrostatic bender. This work summarized the initial result of beam optics design of the beam line. We performed the beam optics simulation in two regions of ISOL beam lines and found that beam envelope is less than 2 cm. We will check that the poletip file values are reasonable or not in near future, and we also applied this method to the other parts of the ISOL beam line and optimize them. The result will be used the detailed design of the electrostatic quadrupoles and benders

Laser Diode Beam Basics, Manipulations and Characterizations

CERN Document Server

Sun, Haiyin

2012-01-01

Many optical design technical books are available for many years which mainly deal with image optics design based on geometric optics and using sequential raytracing technique. Some books slightly touched laser beam manipulation optics design. On the other hand many books on laser diodes have been published that extensively deal with laser diode physics with little touching on laser diode beam manipulations and characterizations. There are some internet resources dealing with laser diode beams. However, these internet resources have not covered enough materials with enough details on laser diode beam manipulations and characterizations. A technical book concentrated on laser diode beam manipulations and characterizations can fit in to the open and provide useful information to laser diode users. Laser Diode Beam Basics, Manipulations and  Characterizations is concentrated on the very practical side of the subject, it only discusses the basic physics and mathematics that are necessary for the readers in order...

Beam Dynamics Studies for a Laser Acceleration Experiment

CERN Document Server

Spencer, James; Noble, Robert; Palmer, Dennis T; Siemann, Robert

2005-01-01

The NLC Test Accelerator at SLAC was built to address various beam dynamics issues for the Next Linear Collider. An S-Band RF gun, originally proposed for the NLCTA, is being installed together with a large-angle extraction line at 60 MeV. This is followed by a matching section, final focus and buncher for the laser acceleration experiment, E163. The laser-electron interaction area is followed by a broad range, high resolution spectrometer (HES) for electron bunch analysis. The RF gun is discussed in another paper. We discuss only the beam dynamics and high resolution analysis system at 6 MeV based on using Parmela and high-order Transport for bunch charges from 50 pC to 1 nC. Beyond the diagnostics, this system uses the emittance compensating solenoids and a low energy, high resolution spectrometer (LES) to help tune for best operating point and match to the linac. Optical symmetries in the design of the 25.5° extraction line provide 1:1 phase space transfer without linear dispersion or use of sextu...

A practical guide to handling laser diode beams

CERN Document Server

Sun, Haiyin

2015-01-01

This book offers the reader a practical guide to the control and characterization of laser diode beams.  Laser diodes are the most widely used lasers, accounting for 50% of the global laser market.  Correct handling of laser diode beams is the key to the successful use of laser diodes, and this requires an in-depth understanding of their unique properties. Following a short introduction to the working principles of laser diodes, the book describes the basics of laser diode beams and beam propagation, including Zemax modeling of a Gaussian beam propagating through a lens.  The core of the book is concerned with laser diode beam manipulations: collimating and focusing, circularization and astigmatism correction, coupling into a single mode optical fiber, diffractive optics and beam shaping, and manipulation of multi transverse mode beams.  The final chapter of the book covers beam characterization methods, describing the measurement of spatial and spectral properties, including wavelength and linewidth meas...

Absorption of aluminium X-ray lines in a laser created gold plasma

International Nuclear Information System (INIS)

Combis, P.; Busquet, M.; Louis-Jacquet, M.

1986-04-01

We have studied the absorption of aluminium X-ray lines through a gold plasma by focusing a high intensity laser-beam onto a specific target. Absorption in the wavelength range of 5 to 7 A has been evidenced and measured for Aluminium resonance lines

Transport and dosimetric solutions for the ELIMED laser-driven beam line

Czech Academy of Sciences Publication Activity Database

Cirrone, G.A.P.; Romano, F.; Scuderi, Valentina; Amato, A.; Candiano, G.; Cuttone, G.; Giove, D.; Korn, Georg; Krása, Josef; Leanza, R.; Manna, R.; Maggiore, M.; Marchese, V.; Margarone, Daniele; Milluzzo, G.; Petringa, G.; Sabini, M.G.; Schillaci, F.; Tramontana, A.; Valastro, L.; Velyhan, Andriy

2015-01-01

Roč. 796, Oct (2015), s. 99-103 ISSN 0168-9002 R&D Projects: GA MŠk ED1.1.00/02.0061; GA MŠk EE2.3.20.0279; GA MŠk EE2.3.30.0057 Grant - others:ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061; LaserZdroj (OP VK 3)(XE) CZ.1.07/2.3.00/20.0279; OP VK 4 POSTDOK(XE) CZ.1.07/2.3.00/30.0057 Institutional support: RVO:68378271 Keywords : laser-driven ion * beam-transport * Faraday cup dosimetry * absolute dosimetry Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.200, year: 2015

Laser-induced fluorescence line narrowing in atomic vapors

International Nuclear Information System (INIS)

Meier, T.; Schuessler, H.A.

1983-01-01

The use of highly monochromatic light allows the selective excitation of atoms in vapors if excitation and detection of the fluorescence is carried out collinearly. The atoms capable of absorbing light then form an atomic beam of well defined velocity along the direction of the laser beam, but no velocity selection occurs perpendicular to it. The potential of the technique for Doppler-free atomic spectroscopy and for the study of excited atom collisions is demonstrated using the Na D 1 line as an example

Suppression of dilution in Ni-Cr-Si-B alloy cladding layer by controlling diode laser beam profile

Science.gov (United States)

Tanigawa, Daichi; Funada, Yoshinori; Abe, Nobuyuki; Tsukamoto, Masahiro; Hayashi, Yoshihiko; Yamazaki, Hiroyuki; Tatsumi, Yoshihiro; Yoneyama, Mikio

2018-02-01

A Ni-Cr-Si-B alloy layer was produced on a type 304 stainless steel plate by laser cladding. In order to produce cladding layer with smooth surface and low dilution, influence of laser beam profile on cladding layer was investigated. A laser beam with a constant spatial intensity at the focus spot was used to suppress droplet formation during the cladding layer formation. This line spot, formed with a focussing unit designed by our group, suppressed droplet generation. The layer formed using this line spot with a constant spatial intensity had a much smoother surface compared to a layer formed using a line spot with a Gaussian-like beam. In addition, the dilution of the former layer was much smaller. These results indicated that a line spot with a constant spatial intensity was more effective in producing a cladding layer with smooth surface and low dilution because it suppressed droplet generation.

Laser-driven acceleration with Bessel beam

International Nuclear Information System (INIS)

Imasaki, Kazuo; Li, Dazhi

2005-01-01

A new approach of laser-driven acceleration with Bessel beam is described. Bessel beam, in contrast to the Gaussian beam, shows diffraction-free'' characteristics in its propagation, which implies potential in laser-driven acceleration. But a normal laser, even if the Bessel beam, laser can not accelerate charged particle efficiently because the difference of velocity between the particle and photon makes cyclic acceleration and deceleration phase. We proposed a Bessel beam truncated by a set of annular slits those makes several special regions in its travelling path, where the laser field becomes very weak and the accelerated particles are possible to receive no deceleration as they undergo decelerating phase. Thus, multistage acceleration is realizable with high gradient. In a numerical computation, we have shown the potential of multistage acceleration based on a three-stage model. (author)

Laser beam cutting method. Laser ko ni yoru kaitai koho

Energy Technology Data Exchange (ETDEWEB)

Kutsumizu, A. (Obayashi Corp., Osaka (Japan))

1991-07-01

In this special issue paper concerning the demolition of concrete structures, was introduced a demolition of concrete structures using laser, of which practical application is expected due to the remarkable progress of generating power and efficiency of laser radiator. The characteristics of laser beam which can give a temperature of one million centigrade at the irradiated spot, the laser radiator consisting of laser medium, laser resonator and pumping apparatus, and the laser kinds for working, such as CO{sub 2} laser, YAG laser and CO laser, were described. The basic constitution of laser cutting equipment consisting of large generating power radiator, beam transmitter, beam condenser, and nozzle for working was also illustrated. Furthermore, strong and weak points in the laser cutting for concrete and reinforcement were enumerated. Applications of laser to cutting of reinforced and unreinforced concrete constructions were shown, and the concept and safety measure for application of laser to practical demolition was discussed. 5 refs., 8 figs.

Laser line scan underwater imaging by complementary metal-oxide-semiconductor camera

Science.gov (United States)

He, Zhiyi; Luo, Meixing; Song, Xiyu; Wang, Dundong; He, Ning

2017-12-01

This work employs the complementary metal-oxide-semiconductor (CMOS) camera to acquire images in a scanning manner for laser line scan (LLS) underwater imaging to alleviate backscatter impact of seawater. Two operating features of the CMOS camera, namely the region of interest (ROI) and rolling shutter, can be utilized to perform image scan without the difficulty of translating the receiver above the target as the traditional LLS imaging systems have. By the dynamically reconfigurable ROI of an industrial CMOS camera, we evenly divided the image into five subareas along the pixel rows and then scanned them by changing the ROI region automatically under the synchronous illumination by the fun beams of the lasers. Another scanning method was explored by the rolling shutter operation of the CMOS camera. The fun beam lasers were turned on/off to illuminate the narrow zones on the target in a good correspondence to the exposure lines during the rolling procedure of the camera's electronic shutter. The frame synchronization between the image scan and the laser beam sweep may be achieved by either the strobe lighting output pulse or the external triggering pulse of the industrial camera. Comparison between the scanning and nonscanning images shows that contrast of the underwater image can be improved by our LLS imaging techniques, with higher stability and feasibility than the mechanically controlled scanning method.

Laser Induced Breakdown Spectroscopy Based on Single Beam Splitting and Geometric Configuration for Effective Signal Enhancement

Science.gov (United States)

Yang, Guang; Lin, Qingyu; Ding, Yu; Tian, Di; Duan, Yixiang

2015-01-01

A new laser induced breakdown spectroscopy (LIBS) based on single-beam-splitting (SBS) and proper optical geometric configuration has been initially explored in this work for effective signal enhancement. In order to improve the interaction efficiency of laser energy with the ablated material, a laser beam operated in pulse mode was divided into two streams to ablate/excite the target sample in different directions instead of the conventional one beam excitation in single pulse LIBS (SP-LIBS). In spatial configuration, the laser beam geometry plays an important role in the emission signal enhancement. Thus, an adjustable geometric configuration with variable incident angle between the two splitted laser beams was constructed for achieving maximum signal enhancement. With the optimized angles of 60° and 70° for Al and Cu atomic emission lines at 396.15 nm and 324.75 nm respectively, about 5.6- and 4.8-folds signal enhancements were achieved for aluminum alloy and copper alloy samples compared to SP-LIBS. Furthermore, the temporal analysis, in which the intensity of atomic lines in SP-LIBS decayed at least ten times faster than the SBS-LIBS, proved that the energy coupling efficiency of SBS-LIBS was significantly higher than that of SP-LIBS. PMID:25557721

Initial alignment method for free space optics laser beam

Science.gov (United States)

Shimada, Yuta; Tashiro, Yuki; Izumi, Kiyotaka; Yoshida, Koichi; Tsujimura, Takeshi

2016-08-01

The authors have newly proposed and constructed an active free space optics transmission system. It is equipped with a motor driven laser emitting mechanism and positioning photodiodes, and it transmits a collimated thin laser beam and accurately steers the laser beam direction. It is necessary to introduce the laser beam within sensible range of the receiver in advance of laser beam tracking control. This paper studies an estimation method of laser reaching point for initial laser beam alignment. Distributed photodiodes detect laser luminescence at respective position, and the optical axis of laser beam is analytically presumed based on the Gaussian beam optics. Computer simulation evaluates the accuracy of the proposed estimation methods, and results disclose that the methods help us to guide the laser beam to a distant receiver.

Self-focusing of laser beams in magnetized relativistic electron beams

International Nuclear Information System (INIS)

Whang, M.H.; Ho, A.Y.; Kuo, S.P.

1989-01-01

Recently, there is considerable interest in radiation focusing and optical guiding using the resonant interaction between the radiation field and electron beam. The result of radiation focusing has been shown to play a central role in the practical utilization of the FEL. This result allows the device to use longer interaction length for achieving higher output power. Likewise, the possibility of self-focusing of the laser beam in cyclotron resonance with a relativistic electron beam is also an important issue in the laser acceleration concepts for achieving high-gradient electron acceleration. The effectiveness of the acceleration process relies strongly on whether the laser intensity can be maintained at the desired level throughout the interaction. In this work, the authors study the problem concerning the self-focusing of laser beam in the relativistic electron beams under the cyclotron auto-resonance interaction. They assume that there is no electron density perturbation prohibited from the background magnetic field for the time scale of interest. The nonlinearity responsible for self-focusing process is introduced by the energy dependence of the relativistic mass of electrons. The plasma frequency varies with the electron energy which is proportional to the radiation amplitude. They then examine such a relativistic nonlinear effect on the propagation of a Gaussian beam in the electron beam. A parametric study of the dependence of the laser beam width on the axial position for various electron beam density has been performed

Beam uniformity of flat top lasers

Science.gov (United States)

Chang, Chao; Cramer, Larry; Danielson, Don; Norby, James

2015-03-01

Many beams that output from standard commercial lasers are multi-mode, with each mode having a different shape and width. They show an overall non-homogeneous energy distribution across the spot size. There may be satellite structures, halos and other deviations from beam uniformity. However, many scientific, industrial and medical applications require flat top spatial energy distribution, high uniformity in the plateau region, and complete absence of hot spots. Reliable standard methods for the evaluation of beam quality are of great importance. Standard methods are required for correct characterization of the laser for its intended application and for tight quality control in laser manufacturing. The International Organization for Standardization (ISO) has published standard procedures and definitions for this purpose. These procedures have not been widely adopted by commercial laser manufacturers. This is due to the fact that they are unreliable because an unrepresentative single-pixel value can seriously distort the result. We hereby propose a metric of beam uniformity, a way of beam profile visualization, procedures to automatically detect hot spots and beam structures, and application examples in our high energy laser production.

Laser-driven ultrafast antiproton beam

Science.gov (United States)

Li, Shun; Pei, Zhikun; Shen, Baifei; Xu, Jiancai; Zhang, Lingang; Zhang, Xiaomei; Xu, Tongjun; Yu, Yong; Bu, Zhigang

2018-02-01

Antiproton beam generation is investigated based on the ultra-intense femtosecond laser pulse by using two-dimensional particle-in-cell and Geant4 simulations. A high-flux proton beam with an energy of tens of GeV is generated in sequential radiation pressure and bubble regime and then shoots into a high-Z target for producing antiprotons. Both yield and energy of the antiproton beam increase almost linearly with the laser intensity. The generated antiproton beam has a short pulse duration of about 5 ps and its flux reaches 2 × 10 20 s - 1 at the laser intensity of 2.14 × 10 23 W / cm 2 . Compared to conventional methods, this new method based on the ultra-intense laser pulse is able to provide a compact, tunable, and ultrafast antiproton source, which is potentially useful for quark-gluon plasma study, all-optical antihydrogen generation, and so on.

Laser-driven ion acceleration with hollow laser beams

International Nuclear Information System (INIS)

Brabetz, C.; Kester, O.; Busold, S.; Bagnoud, V.; Cowan, T.; Deppert, O.; Jahn, D.; Roth, M.; Schumacher, D.

2015-01-01

The laser-driven acceleration of protons from thin foils irradiated by hollow high-intensity laser beams in the regime of target normal sheath acceleration (TNSA) is reported for the first time. The use of hollow beams aims at reducing the initial emission solid angle of the TNSA source, due to a flattening of the electron sheath at the target rear side. The experiments were conducted at the PHELIX laser facility at the GSI Helmholtzzentrum für Schwerionenforschung GmbH with laser intensities in the range from 10 18  W cm −2 to 10 20  W cm −2 . We observed an average reduction of the half opening angle by (3.07±0.42)° or (13.2±2.0)% when the targets have a thickness between 12 μm and 14 μm. In addition, the highest proton energies were achieved with the hollow laser beam in comparison to the typical Gaussian focal spot

Laser-driven ion acceleration with hollow laser beams

Energy Technology Data Exchange (ETDEWEB)

Brabetz, C., E-mail: c.brabetz@gsi.de; Kester, O. [Goethe-Universität Frankfurt am Main, 60323 Frankfurt (Germany); GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Busold, S.; Bagnoud, V. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Helmholtz-Institut Jena, 07743 Jena (Germany); Cowan, T. [Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden (Germany); Technische Universität Dresden, 01069 Dresden (Germany); Deppert, O.; Jahn, D.; Roth, M. [Technische Universität Darmstadt, 64277 Darmstadt (Germany); Schumacher, D. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt (Germany)

2015-01-15

The laser-driven acceleration of protons from thin foils irradiated by hollow high-intensity laser beams in the regime of target normal sheath acceleration (TNSA) is reported for the first time. The use of hollow beams aims at reducing the initial emission solid angle of the TNSA source, due to a flattening of the electron sheath at the target rear side. The experiments were conducted at the PHELIX laser facility at the GSI Helmholtzzentrum für Schwerionenforschung GmbH with laser intensities in the range from 10{sup 18} W cm{sup −2} to 10{sup 20} W cm{sup −2}. We observed an average reduction of the half opening angle by (3.07±0.42)° or (13.2±2.0)% when the targets have a thickness between 12 μm and 14 μm. In addition, the highest proton energies were achieved with the hollow laser beam in comparison to the typical Gaussian focal spot.

Method and apparatus for laser-controlled proton beam radiology

Science.gov (United States)

Johnstone, Carol J.

1998-01-01

A proton beam radiology system provides cancer treatment and proton radiography. The system includes an accelerator for producing an H.sup.- beam and a laser source for generating a laser beam. A photodetachment module is located proximate the periphery of the accelerator. The photodetachment module combines the H.sup.- beam and laser beam to produce a neutral beam therefrom within a subsection of the H.sup.- beam. The photodetachment module emits the neutral beam along a trajectory defined by the laser beam. The photodetachment module includes a stripping foil which forms a proton beam from the neutral beam. The proton beam is delivered to a conveyance segment which transports the proton beam to a patient treatment station. The photodetachment module further includes a laser scanner which moves the laser beam along a path transverse to the cross-section of the H.sup.- beam in order to form the neutral beam in subsections of the H.sup.- beam. As the scanning laser moves across the H.sup.- beam, it similarly varies the trajectory of the proton beam emitted from the photodetachment module and in turn varies the target location of the proton beam upon the patient. Intensity modulation of the proton beam can also be achieved by controlling the output of the laser.

Controlling Second Harmonic Efficiency of Laser Beam Interactions

Science.gov (United States)

Barnes, Norman P. (Inventor); Walsh, Brian M. (Inventor); Reichle, Donald J. (Inventor)

2011-01-01

A method is provided for controlling second harmonic efficiency of laser beam interactions. A laser system generates two laser beams (e.g., a laser beam with two polarizations) for incidence on a nonlinear crystal having a preferred direction of propagation. Prior to incidence on the crystal, the beams are optically processed based on the crystal's beam separation characteristics to thereby control a position in the crystal along the preferred direction of propagation at which the beams interact.

Raman beam combining for laser brightness enhancement

Science.gov (United States)

Dawson, Jay W.; Allen, Graham S.; Pax, Paul H.; Heebner, John E.; Sridharan, Arun K.; Rubenchik, Alexander M.; Barty, Chrisopher B. J.

2015-10-27

An optical source capable of enhanced scaling of pulse energy and brightness utilizes an ensemble of single-aperture fiber lasers as pump sources, with each such fiber laser operating at acceptable pulse energy levels. Beam combining involves stimulated Raman scattering using a Stokes' shifted seed beam, the latter of which is optimized in terms of its temporal and spectral properties. Beams from fiber lasers can thus be combined to attain pulses with peak energies in excess of the fiber laser self-focusing limit of 4 MW while retaining the advantages of a fiber laser system of high average power with good beam quality.

High power electron beam accelerators for gas laser excitation

International Nuclear Information System (INIS)

Kelly, J.G.; Martin, T.H.; Halbleib, J.A.

1976-06-01

A preliminary parameter investigation has been used to determine a possible design of a high-power, relativistic electron beam, transversely excited laser. Based on considerations of present and developing pulsed power technology, broad area diode physics and projected laser requirements, an exciter is proposed consisting of a Marx generator, pulse shaping transmission lines, radially converging ring diodes and a laser chamber. The accelerator should be able to deliver approximately 20 kJ of electron energy at 1 MeV to the 10 4 cm 2 cylindrical surface of a laser chamber 1 m long and 0.3 m in diameter in 24 ns with very small azimuthal asymmetry and uniform radial deposition

Beam Transfer Line Design for a Plasma Wakefield Acceleration Experiment (AWAKE) at the CERN SPS

CERN Document Server

Bracco, C; Brethoux, D; Clerc, V; Goddard, B; Gschwendtner, E; Jensen, L K; Kosmicki, A; Le Godec, G; Meddahi, M; Muggli, P; Mutin, C; Osborne, O; Papastergiou, K; Pardons, A; Velotti, F M; Vincke, H

2013-01-01

The world’s first proton driven plasma wakefield acceleration experiment (AWAKE) is presently being studied at CERN. The experimentwill use a high energy proton beam extracted from the SPS as driver. Two possible locations for installing the AWAKE facility were considered: the West Area and the CNGS beam line. The previous transfer line from the SPS to the West Area was completely dismantled in 2005 and would need to be fully re-designed and re-built. For this option, geometric constraints for radiation protection reasons would limit the maximum proton beam energy to 300 GeV. The existing CNGS line could be used by applying only minor changes to the lattice for the final focusing and the interface between the proton beam and the laser, required for plasma ionisation and bunch-modulation seeding. The beam line design studies performed for the two options are presented.

Collisional absorption of two laser beams in plasma

International Nuclear Information System (INIS)

Mohan, M.; Acharya, R.

1977-04-01

The collisional absorption of two laser beams is considered by solving the kinetic equation for the plasma electron. Results show that the simultaneous effect of two laser beams on the heating rate is greater as compared with the individual contribution of each laser beam when the two laser beams have a difference of frequencies equal to the plasma frequency

Laser systems configured to output a spectrally-consolidated laser beam and related methods

Science.gov (United States)

Koplow, Jeffrey P [San Ramon, CA

2012-01-10

A laser apparatus includes a plurality of pumps each of which is configured to emit a corresponding pump laser beam having a unique peak wavelength. The laser apparatus includes a spectral beam combiner configured to combine the corresponding pump laser beams into a substantially spatially-coherent pump laser beam having a pump spectrum that includes the unique peak wavelengths, and first and second selectively reflective elements spaced from each other to define a lasing cavity including a lasing medium therein. The lasing medium generates a plurality of gain spectra responsive to absorbing the pump laser beam. Each gain spectrum corresponds to a respective one of the unique peak wavelengths of the substantially spatially-coherent pump laser beam and partially overlaps with all other ones of the gain spectra. The reflective elements are configured to promote emission of a laser beam from the lasing medium with a peak wavelength common to each gain spectrum.

Beam line design using G4BeamLine

CERN Document Server

Dogan, Arda

2014-01-01

In Turkey in Ankara TAEK SANAEM Proton Accelerator Facility (PAF), there is a cyclotron which produces a focused intense 30 MeV proton beam and sends this beam to four different arms, three of which uses this beam to produce pharmaceutical medicine. The remaining one is spared for R&D purposes and the idea was to use these protons coming out from the fourth arm to use space radiation tests, which cannot be done in Turkey at the moment. However, according to SCC 25100 standards which is for 30 MeV protons, the beam coming out of cyclotron is too intense and focused to use for space radiation tests. Therefore, the main aim of my project is to design a beam line which will defocus the beam and reduce the flux so that the space radiation tests can be done according to the standards of SCC 25100.

The Final Focus Test Beam laser referene system

International Nuclear Information System (INIS)

Bressler, V.E.; Ruland, R.E.

1993-05-01

The original design for the SLAC linac included an alignment reference system with 270 diffraction gratings situated along the 3000 meter linac. These gratings have provided SLAC with a global reference line repeatable to within 200 micro meters. For the Final Focus Test Beam, this laser system has been extended and 13 new diffraction gratings have been installed. Improvements targets and the availability of new instruments allows us to evaluate the performance of the laser reference system at the 510 micro meter level. An explanation of the system and the results of our evaluation are presented

Thermal analysis of line-defect photonic crystal lasers

DEFF Research Database (Denmark)

Xue, Weiqi; Ottaviano, Luisa; Chen, Yaohui

2015-01-01

under CW optical pumping, whereas InGaAsP membranes only lase under pulsed conditions. By varying the duty cycle of the pump beam, we quantify the heating induced by optical pumping in the two material platforms and compare their thermal properties. Full 3D finite element simulations show the spatial......We report a systematic study of thermal effects in photonic crystal membrane lasers based on line-defect cavities. Two material platforms, InGaAsP and InP, are investigated experimentally and numerically. Lasers with quantum dot layers embedded in an InP membrane exhibit lasing at room temperature...

Excimer laser beam delivery systems for medical applications

Science.gov (United States)

Kubo, Uichi; Hashishin, Yuichi; Okada, Kazuyuki; Tanaka, Hiroyuki

1993-05-01

We have been doing the basic experiments of UV laser beams and biotissue interaction with both KrF and XeCl lasers. However, the conventional optical fiber can not be available for power UV beams. So we have been investigating about UV power beam delivery systems. These experiments carry on with the same elements doped quartz fibers and the hollow tube. The doped elements are OH ion, chlorine and fluorine. In our latest work, we have tried ArF excimer laser and biotissue interactions, and the beam delivery experiments. From our experimental results, we found that the ArF laser beam has high incision ability for hard biotissue. For example, in the case of the cow's bone incision, the incision depth by ArF laser was ca.15 times of KrF laser. Therefore, ArF laser would be expected to harden biotissue therapy as non-thermal method. However, its beam delivery is difficult to work in this time. We will develop ArF laser beam delivery systems.

Laser control of atomic beam motion and applications

International Nuclear Information System (INIS)

Balykin, V.I.; Letokhov, V.S.

1987-01-01

The authors present the results of an experimental investigation of the control of atomic beam motion by the light pressure of laser radiation. Collimation, focusing and reflection of the atomic beam are considered. Collimation of the atomic beam is achieved by the interaction of laser radiation with atoms, when the light pressure force depends only on the atom's velocity. A similar regime of atomic beam interaction with radiation was performed with transversal irradiation of a beam by the axis-symmetrical field. The axis-symmetrical field was formed by laser radiation reflected from the conical mirror surface of a reflecting axicon. The axis of the atomic beam coincided with that of the axicon. The collimation regime was reached under negative detuning of the laser radiation frequency from the atomic transition frequency by a value equal to several homogeneous widths. With positive detuning by the same value the regime of beam decollimation was observed. The density of atoms on the beam axis was changed by 10 3 times, when the collimation regime was replaced by that of decollimation. Focusing of the atomic beam was achieved by light pressure dependent on the atomic coordinate. Focusing was performed within the field configuration formed by divergent laser Gaussian beams propagating in the direction +- X, +- Y of a Cartesian coordinate system. Waists of the laser beams were an equal distance from the atomic beam axis. With an atomic beam propagating along the z axis, expressions for local distance and a formula for the laser lens were obtained. Focusing of the atomic beam was experimentally accomplished, and the image of the atomic beam was received. In this work they also investigated reflection of the atomic beam by laser radiation. The possibility of creating the optics of a neutral atomic beam is shown

Production and characterization of femtosecond laser-written double line waveguides in heavy metal oxide glasses

Science.gov (United States)

da Silva, Diego Silvério; Wetter, Niklaus Ursus; de Rossi, Wagner; Kassab, Luciana Reyes Pires; Samad, Ricardo Elgul

2018-01-01

We report the fabrication and characterization of double line waveguides directly written in tellurite and germanate glasses using a femtosecond laser delivering 30 μJ, 80 fs pulses at 4 kHz repetition rate. The double line waveguides produced presented internal losses inferior to 2.0 dB/cm. The output mode profile and the M2 measurements indicate multimodal guiding behavior. A better beam quality for the GeO2 - PbO waveguide was observed when compared with TeO2 - ZnO glass. Raman spectroscopy of the waveguides showed structural modification of the glassy network and indicates that a negative refractive index modification occurs at the focus of the laser beam, therefore allowing for light guiding in between two closely spaced laser written lines. The refractive index change at 632 nm is around 10-4, and the structural changes in the laser focal region of the writing, evaluated by Raman spectroscopy, corroborated our findings that these materials are potential candidates for optical waveguides and passive components. To the best of our knowledge, the two double line configuration demonstrated in the present work was not reported before for germanate or tellurite glasses.

Wavefront measurement of single-mode quantum cascade laser beam for seed application in laser-produced plasma extreme ultraviolet system.

Science.gov (United States)

Nowak, Krzysztof M; Ohta, Takeshi; Suganuma, Takashi; Yokotsuka, Toshio; Fujimoto, Junichi; Mizoguchi, Hakaru

2012-12-01

Quantum cascade laser (QCL) is a very attractive seed source for a multikilowatt pulsed CO2 lasers applied for driving extreme ultraviolet emitting plasmas. In this Letter, we investigate output beam properties of a QCL designed to address P18 and P20 lines of 10.6 micron band of CO2 molecule. In particular, output beam quality and stability are investigated for the first time. A well-defined linear polarization and a single-mode operation enabled a use of phase retrieval method for full description of QCL output beam. A direct, multi-image numerical phase retrieval technique was developed and successfully applied to the measured intensity patterns of a QCL beam. Very good agreement between the measured and reconstructed beam profiles was observed at distances ranging from QCL aperture to infinity, proving a good understanding of the beam propagation. The results also confirm a high spatial coherence and high stability of the beam parameters, the features expected from an excellent seed source.

Time of Flight based diagnostics for high energy laser driven ion beams

Science.gov (United States)

Scuderi, V.; Milluzzo, G.; Alejo, A.; Amico, A. G.; Booth, N.; Cirrone, G. A. P.; Doria, D.; Green, J.; Kar, S.; Larosa, G.; Leanza, R.; Margarone, D.; McKenna, P.; Padda, H.; Petringa, G.; Pipek, J.; Romagnani, L.; Romano, F.; Schillaci, F.; Borghesi, M.; Cuttone, G.; Korn, G.

2017-03-01

Nowadays the innovative high power laser-based ion acceleration technique is one of the most interesting challenges in particle acceleration field, showing attractive characteristics for future multidisciplinary applications, including medical ones. Nevertheless, peculiarities of optically accelerated ion beams make mandatory the development of proper transport, selection and diagnostics devices in order to deliver stable and controlled ion beams for multidisciplinary applications. This is the main purpose of the ELIMAIA (ELI Multidisciplinary Applications of laser-Ion Acceleration) beamline that will be realized and installed within 2018 at the ELI-Beamlines research center in the Czech Republic, where laser driven high energy ions, up to 60 MeV/n, will be available for users. In particular, a crucial role will be played by the on-line diagnostics system, recently developed in collaboration with INFN-LNS (Italy), consisting of TOF detectors, placed along the beamline (at different detection distances) to provide online monitoring of key characteristics of delivered beams, such as energy, fluence and ion species. In this contribution an overview on the ELIMAIA available ion diagnostics will be briefly given along with the preliminary results obtained during a test performed with high energy laser-driven proton beams accelerated at the VULCAN PW-laser available at RAL facility (U.K.).

Time of Flight based diagnostics for high energy laser driven ion beams

International Nuclear Information System (INIS)

Scuderi, V.; Margarone, D.; Schillaci, F.; Milluzzo, G.; Amico, A.G.; Cirrone, G.A.P.; Larosa, G.; Leanza, R.; Petringa, G.; Pipek, J.; Romano, F.; Alejo, A.; Doria, D.; Kar, S.; Borghesi, M.; Booth, N.; Green, J.; McKenna, P.; Padda, H.; Romagnani, L.

2017-01-01

Nowadays the innovative high power laser-based ion acceleration technique is one of the most interesting challenges in particle acceleration field, showing attractive characteristics for future multidisciplinary applications, including medical ones. Nevertheless, peculiarities of optically accelerated ion beams make mandatory the development of proper transport, selection and diagnostics devices in order to deliver stable and controlled ion beams for multidisciplinary applications. This is the main purpose of the ELIMAIA (ELI Multidisciplinary Applications of laser-Ion Acceleration) beamline that will be realized and installed within 2018 at the ELI-Beamlines research center in the Czech Republic, where laser driven high energy ions, up to 60 MeV/n, will be available for users. In particular, a crucial role will be played by the on-line diagnostics system, recently developed in collaboration with INFN-LNS (Italy), consisting of TOF detectors, placed along the beamline (at different detection distances) to provide online monitoring of key characteristics of delivered beams, such as energy, fluence and ion species. In this contribution an overview on the ELIMAIA available ion diagnostics will be briefly given along with the preliminary results obtained during a test performed with high energy laser-driven proton beams accelerated at the VULCAN PW-laser available at RAL facility (U.K.).

Laser diagnostics for picosecond e-beams

International Nuclear Information System (INIS)

Pogorelsky, I.; Ben-Zvi, I.

1992-01-01

We propose a novel approach to picosecond e-bunch/laser pulse synchronization and spatial alignment based upon refraction and reflection of a laser beam on a plasma column created by relativistic electrons traveling through a gas or solid optical material. The technique may be used in laser accelerators and for general subpicosecond e-beam diagnostics

Status of ACCULINNA beam line

CERN Document Server

Rodin, A M; Bogdanov, D D; Golovkov, M S; Fomichev, A S; Sidorchuk, S I; Slepnev, R S; Wolski, R; Ter-Akopian, G M; Oganessian, Yu T; Yukhimchuk, A A; Perevozchikov, V V; Vinogradov, Yu I; Grishenchkin, S K; Demin, A M; Zlatoustovskii, S V; Kuryakin, A V; Filchagin, S V; Ilkaev, R I

2003-01-01

The separator ACCULINNA was upgraded to achieve new experimental requirements. The beam line was extended by new ion-optical elements beyond the cyclotron hall. The new arrangements yield much better background conditions. The intensities of sup 6 He and sup 8 He radioactive beams produced in fragmentation of 35 A MeV sup 1 sup 1 B ions were increased up to a factor of 10. The upgraded beam line was used in experiments to study the sup 5 H resonance states populated in the t+t reaction. A cryogenic liquid tritium target was designed and installed at the separator beam line.

The Two-Beam Free Electron Laser Oscillator

CERN Document Server

Thompson, Neil R

2004-01-01

A one-dimensional model of a free-electron laser operating simultaneously with two electron beams of different energies [1] is extended to an oscillator configuration. The electron beam energies are chosen so that an harmonic of the lower energy beam is at the fundamental radiation wavelength of the higher energy beam. Potential benefits over a single-beam free-electron laser oscillator are discussed.

Modification of beam lines at VEC

Energy Technology Data Exchange (ETDEWEB)

Shoor, Bivas; Chakraborty, P S; Mallik, C; Bhandari, R K [Variable Energy Cyclotron Centre, Calcutta (India)

1997-12-01

From the experience of light ion beam transportation through the Variable Energy Cyclotron beam line, it was observed that the beam line performance has to be improved in view of heavy ion acceleration program at the centre. The aim of this work was to study the feasibility of reducing the number of operational parameters without hampering the beam transmission and at the same time, to improve the vacuum of the beam line by reducing the hardware 2 refs., 1 fig.

Measurements of laser-imprinting sensitivity to relative beam mistiming in planar plastic foils driven by multiple overlapping laser beams

International Nuclear Information System (INIS)

Smalyuk, V.A.; Goncharov, V.N.; Boehly, T.R.; Delettrez, J.A.; Li, D.Y.; Marozas, J.A.; Maximov, A.V.; Meyerhofer, D.D.; Regan, S.P.; Sangster, T.C.

2005-01-01

In a direct-drive, inertial confinement fusion implosion, a spherical target is irradiated by a large number of overlapped laser beams. Imprinting of laser modulations depends on the relative arrival time of laser beams and their angles of incidence. This dependence was measured in planar plastic targets using six overlapping beams on the OMEGA laser system [T. R. Boehly, D. L. Brown, R. S. Craxton, R. L. Keck, J. P. Knauer, J. H. Kelly, T. J. Kessler, S. A. Kumpan, S. J. Loucks, S. A. Letzring, F. J. Marshall, R. L. McCrory, S. F. B. Morse, W. Seka, J. M. Soures, and C. P. Verdon, Opt. Commun. 133, 495 (1997)]. One of the beams (the imprint beam) had a special phase plate that produced two-dimensional modulations on the target, easily distinguishable from the features imprinted by the other five drive beams. The timing of the imprint beam was varied with respect to the drive beams to study imprinting sensitivity to beam mistiming. Shifting the imprint beam to arrive before the other beams significantly increased the imprint efficiency. The results are in very good agreement with the model predictions

Laser-driven acceleration with Bessel and Gaussian beams

International Nuclear Information System (INIS)

Hafizi, B.; Esarey, E.; Sprangle, P.

1997-01-01

The possibility of enhancing the energy gain in laser-driven accelerators by using Bessel laser beams is examined. Scaling laws are derived for the propagation length, acceleration gradient, and energy gain in various accelerators for both Gaussian and Bessel beam drivers. For equal beam powers, the energy gain can be increased by a factor of N 1/2 by utilizing a Bessel beam with N lobes, provided that the acceleration gradient is linearly proportional to the laser field. This is the case in the inverse free electron laser and the inverse Cherenkov accelerators. If the acceleration gradient is proportional to the square of the laser field (e.g., the laser wakefield, plasma beat wave, and vacuum beat wave accelerators), the energy gain is comparable with either beam profile. copyright 1997 American Institute of Physics

Resonance ionization laser ion sources for on-line isotope separators (invited)

International Nuclear Information System (INIS)

Marsh, B. A.

2014-01-01

A Resonance Ionization Laser Ion Source (RILIS) is today considered an essential component of the majority of Isotope Separator On Line (ISOL) facilities; there are seven laser ion sources currently operational at ISOL facilities worldwide and several more are under development. The ionization mechanism is a highly element selective multi-step resonance photo-absorption process that requires a specifically tailored laser configuration for each chemical element. For some isotopes, isomer selective ionization may even be achieved by exploiting the differences in hyperfine structures of an atomic transition for different nuclear spin states. For many radioactive ion beam experiments, laser resonance ionization is the only means of achieving an acceptable level of beam purity without compromising isotope yield. Furthermore, by performing element selection at the location of the ion source, the propagation of unwanted radioactivity downstream of the target assembly is reduced. Whilst advances in laser technology have improved the performance and reliability of laser ion sources and broadened the range of suitable commercially available laser systems, many recent developments have focused rather on the laser/atom interaction region in the quest for increased selectivity and/or improved spectral resolution. Much of the progress in this area has been achieved by decoupling the laser ionization from competing ionization processes through the use of a laser/atom interaction region that is physically separated from the target chamber. A new application of gas catcher laser ion source technology promises to expand the capabilities of projectile fragmentation facilities through the conversion of otherwise discarded reaction fragments into high-purity low-energy ion beams. A summary of recent RILIS developments and the current status of laser ion sources worldwide is presented

submitter Triggering of a pressurized spark gap by a laser beam

CERN Document Server

Deutsch, F

1968-01-01

A delay line was discharged into a terminating resistor by a spark gap of coaxial design. The spark gap was triggered by a focused laser beam, introduced along the axis; a Q-switched ruby laser giving pulses of 20 ns duration and up to 50 MW power was used. The range of operation of the gap, formative time of the breakdown and jitter were investigated for different gases at pressures above atmospheric, gap widths of 4-10 mm and voltages of up to 120 kv. Mixtures of argon and nitrogen were found to have certain advantages, such as a low threshold for ionization by the laser beam, sufficient dielectric strength, low values of the formative-time jitter and chemical inertness. Formative times of down to about 1 ns and jitters below 1 ns were found. The laser power can be relatively low (0centerdot5-5 MW). An explanation for the breakdown mechanism is proposed.

Self-amplified spontaneous emission free electron laser devices and nonideal electron beam transport

Directory of Open Access Journals (Sweden)

L. L. Lazzarino

2014-11-01

Full Text Available We have developed, at the SPARC test facility, a procedure for a real time self-amplified spontaneous emission free electron laser (FEL device performance control. We describe an actual FEL, including electron and optical beam transport, through a set of analytical formulas, allowing a fast and reliable on-line “simulation” of the experiment. The system is designed in such a way that the characteristics of the transport elements and the laser intensity are measured and adjusted, via a real time computation, during the experimental run, to obtain an on-line feedback of the laser performances. The detail of the procedure and the relevant experimental results are discussed.

Measuring contact angle and meniscus shape with a reflected laser beam.

Science.gov (United States)

Eibach, T F; Fell, D; Nguyen, H; Butt, H J; Auernhammer, G K

2014-01-01

Side-view imaging of the contact angle between an extended planar solid surface and a liquid is problematic. Even when aligning the view perfectly parallel to the contact line, focusing one point of the contact line is not possible. We describe a new measurement technique for determining contact angles with the reflection of a widened laser sheet on a moving contact line. We verified this new technique measuring the contact angle on a cylinder, rotating partially immersed in a liquid. A laser sheet is inclined under an angle φ to the unperturbed liquid surface and is reflected off the meniscus. Collected on a screen, the reflection image contains information to determine the contact angle. When dividing the laser sheet into an array of laser rays by placing a mesh into the beam path, the shape of the meniscus can be reconstructed from the reflection image. We verified the method by measuring the receding contact angle versus speed for aqueous cetyltrimethyl ammonium bromide solutions on a smooth hydrophobized as well as on a rough polystyrene surface.

Laser beam shaping design based on micromirror array

Science.gov (United States)

Fang, Han; Su, Bida; Liu, Jiaguo; Fan, Xiaoli; Jing, Wang

2017-10-01

In the practical application of the laser, it is necessary to use the laser beam shaping technology to shape the output beam of laser device to the uniform light intensity distribution. The shaping divergent optical system of compound eye integrator way is composed of beam expanding mirror group and lens array. Its working principle is to expand the output laser to a certain size of caliber, and then divide the beam with lens array into multiple sub beam, where the lens unit of lens array can control the divergence angle of sub beam through the design of focal length, with mutual superposition of the sub beam in far field, to make up for the nonuniformity of beam, so that the radiant exitance on the radiated surface may become uniform. In this paper, we use a reflective microlens array to realize the laser beam shaping. By through of the practical optical path model established, the ray tracing is carried out and the simulation results for single-mode Gaussian beam with noise circumstance is provided. The analysis results show that the laser beam shaping under different inputs can be effectively realized by use of microlens array. All the energy is within the signal window, with a high energy efficiency of more than 90%; The measured surface has a better uniformity, and the uniformity is better than 99.5% at 150m.

Diffractive beam shaping for enhanced laser polymer welding

Science.gov (United States)

Rauschenberger, J.; Vogler, D.; Raab, C.; Gubler, U.

2015-03-01

Laser welding of polymers increasingly finds application in a large number of industries such as medical technology, automotive, consumer electronics, textiles or packaging. More and more, it replaces other welding technologies for polymers, e. g. hot-plate, vibration or ultrasonic welding. At the same rate, demands on the quality of the weld, the flexibility of the production system and on processing speed have increased. Traditionally, diode lasers were employed for plastic welding with flat-top beam profiles. With the advent of fiber lasers with excellent beam quality, the possibility to modify and optimize the beam profile by beam-shaping elements has opened. Diffractive optical elements (DOE) can play a crucial role in optimizing the laser intensity profile towards the optimal M-shape beam for enhanced weld seam quality. We present results on significantly improved weld seam width constancy and enlarged process windows compared to Gaussian or flat-top beam profiles. Configurations in which the laser beam diameter and shape can be adapted and optimized without changing or aligning the laser, fiber-optic cable or optical head are shown.

Biomimetic surface structuring using cylindrical vector femtosecond laser beams

Science.gov (United States)

Skoulas, Evangelos; Manousaki, Alexandra; Fotakis, Costas; Stratakis, Emmanuel

2017-03-01

We report on a new, single-step and scalable method to fabricate highly ordered, multi-directional and complex surface structures that mimic the unique morphological features of certain species found in nature. Biomimetic surface structuring was realized by exploiting the unique and versatile angular profile and the electric field symmetry of cylindrical vector (CV) femtosecond (fs) laser beams. It is shown that, highly controllable, periodic structures exhibiting sizes at nano-, micro- and dual- micro/nano scales can be directly written on Ni upon line and large area scanning with radial and azimuthal polarization beams. Depending on the irradiation conditions, new complex multi-directional nanostructures, inspired by the Shark’s skin morphology, as well as superhydrophobic dual-scale structures mimicking the Lotus’ leaf water repellent properties can be attained. It is concluded that the versatility and features variations of structures formed is by far superior to those obtained via laser processing with linearly polarized beams. More important, by exploiting the capabilities offered by fs CV fields, the present technique can be further extended to fabricate even more complex and unconventional structures. We believe that our approach provides a new concept in laser materials processing, which can be further exploited for expanding the breadth and novelty of applications.

An intense polarized beam by a laser ionization injection

International Nuclear Information System (INIS)

Ohmori, Chihiro; Hiramatsu, Shigenori; Nakamura, Takeshi.

1990-12-01

Accumulation of protons and polarized protons by photo-ionization injection are described. This method consists of (1)producing the neutral hydrogen beam by Lorentz stripping, (2)excitation of the neutral hydrogen beam with a laser, and (3)ionization of the hydrogen beam in the 2P excited state with another laser. When the laser for the excitation is circularly polarized, we can get a polarized proton beam. An ionization efficiency of 98% and a polarization of 80% can be expected by an intense laser beam from a FEL(Free Electron Laser). (author)

Optics with an Atom Laser Beam

International Nuclear Information System (INIS)

Bloch, Immanuel; Koehl, Michael; Greiner, Markus; Haensch, Theodor W.; Esslinger, Tilman

2001-01-01

We report on the atom optical manipulation of an atom laser beam. Reflection, focusing, and its storage in a resonator are demonstrated. Precise and versatile mechanical control over an atom laser beam propagating in an inhomogeneous magnetic field is achieved by optically inducing spin flips between atomic ground states with different magnetic moment. The magnetic force acting on the atoms can thereby be effectively switched on and off. The surface of the atom optical element is determined by the resonance condition for the spin flip in the inhomogeneous magnetic field. More than 98% of the incident atom laser beam is reflected specularly

Achromatic and isochronous electron beam transport for tunable free electron lasers

International Nuclear Information System (INIS)

Bengtsson, J.; Kim, K.J.

1991-09-01

We have continued the study of a suitable electron beam transport line, which is both isochronous and achromatic, for the free electron laser being designed at Lawrence Berkeley Laboratory. A refined version of the beam transport optics is discussed that accommodates two different modes of FEL wavelength tuning. For the fine tuning involving a small change of the electron beam energy, sextupoles are added to cancel the leading nonlinear dispersion. For the main tuning involving the change of the undulator gap, a practical solution of maintaining the beam matching condition is presented. Calculation of the higher order aberrations is facilitated by a newly developed code. 11 refs., 4 figs., 3 tabs

Theoretical predictions for the polarization of the J = 0 - 1 neonlike germanium X-ray laser line in the presence of a directed beam of hot electrons

International Nuclear Information System (INIS)

Inal, M.K.; Dubau, J.; Cornille, M.

1998-01-01

The polarization of the neonlike germanium J = 0 - 1 laser line, which would arise from the existence of a directed beam of hot electrons in the amplifying plasma, is theoretically investigated. The relative populations of the magnetic sublevels in the lower J = 1 laser level have been determined by allowing for the processes of direct excitation from the 2p 6 ground level and collisional de-excitation from the upper J = 0 laser level. Elastic collisions leading to transitions between the M J = 0 and M J =1 sublevels within the lower level of the lasing line have also been taken into account. The required elastic and inelastic collision strengths for transitions between magnetic sublevels have been computed in a semi-relativistic distorted-wave approximation, for incident electron energies up to 15 keV. Our calculations predict a rather low degree of polarization for the J = 0 - 1 line, although the elastic collisions are found to play a negligibly small role in the redistribution of magnetic sublevel populations. (author)

Doughnut laser beam as an incoherent superposition of two petal beams

CSIR Research Space (South Africa)

Litvin, IA

2014-02-01

Full Text Available Laguerre–Gaussian beams with a nonzero azimuthal index are known to carry orbital angular momentum (OAM), and are routinely created external to laser cavities. The few reports of obtaining such beams from laser cavities suffer from inconclusive...

Simulation based analysis of laser beam brazing

Science.gov (United States)

Dobler, Michael; Wiethop, Philipp; Schmid, Daniel; Schmidt, Michael

2016-03-01

Laser beam brazing is a well-established joining technology in car body manufacturing with main applications in the joining of divided tailgates and the joining of roof and side panels. A key advantage of laser brazed joints is the seam's visual quality which satisfies highest requirements. However, the laser beam brazing process is very complex and process dynamics are only partially understood. In order to gain deeper knowledge of the laser beam brazing process, to determine optimal process parameters and to test process variants, a transient three-dimensional simulation model of laser beam brazing is developed. This model takes into account energy input, heat transfer as well as fluid and wetting dynamics that lead to the formation of the brazing seam. A validation of the simulation model is performed by metallographic analysis and thermocouple measurements for different parameter sets of the brazing process. These results show that the multi-physical simulation model not only can be used to gain insight into the laser brazing process but also offers the possibility of process optimization in industrial applications. The model's capabilities in determining optimal process parameters are exemplarily shown for the laser power. Small deviations in the energy input can affect the brazing results significantly. Therefore, the simulation model is used to analyze the effect of the lateral laser beam position on the energy input and the resulting brazing seam.

NIF Laser Line Replaceable Units (LRUs)

International Nuclear Information System (INIS)

Larson, D W

2003-01-01

The National Ignition Facility (NIF) is designed with its high value optical systems in cassettes called Line Replaceable Units (LRUs). Virtually all of the NIF's active components are assembled in one of the ∼4000 electrical and optical LRUs that serve between two and eight of NIF's 192 laser beam lines. Many of these LRUs are optomechanical assemblies that are roughly the size of a telephone booth. The primary design challenges for this hardware include meeting stringent mechanical precision, stability and cleanliness requirements. Pre-production units of each LRU type have been fielded on the first bundle of NIF and used to demonstrate that NIF meets its performance objectives. This presentation provides an overview of the NIF LRUs, their design and production plans for building out the remaining NIF bundles

Symmetric compression of 'laser greenhouse' targets by a few laser beams

International Nuclear Information System (INIS)

Gus'kov, Sergei Yu; Demchenko, N N; Rozanov, Vladislav B; Stepanov, R V; Zmitrenko, N V; Caruso, A; Strangio, C

2003-01-01

The possibility of efficient and symmetric compression of a target with a low-density structured absorber by a few laser beams is considered. An equation of state is proposed for a porous medium, which takes into account the special features of the absorption of high-power nanosecond laser pulses. The open version of this target is shown to allow the use of ordinary Gaussian beams, requiring no special profiling of the absorber surface. The conditions are defined under which such targets can be compressed efficiently by only two laser beams (or beam clusters). Simulations show that for a 2.1-MJ laser pulse, a seven-fold gain for the target under study is achieved. (special issue devoted to the 80th anniversary of academician n g basov's birth)

Compact compressive arc and beam switchyard for energy recovery linac-driven ultraviolet free electron lasers

Science.gov (United States)

Akkermans, J. A. G.; Di Mitri, S.; Douglas, D.; Setija, I. D.

2017-08-01

High gain free electron lasers (FELs) driven by high repetition rate recirculating accelerators have received considerable attention in the scientific and industrial communities in recent years. Cost-performance optimization of such facilities encourages limiting machine size and complexity, and a compact machine can be realized by combining bending and bunch length compression during the last stage of recirculation, just before lasing. The impact of coherent synchrotron radiation (CSR) on electron beam quality during compression can, however, limit FEL output power. When methods to counteract CSR are implemented, appropriate beam diagnostics become critical to ensure that the target beam parameters are met before lasing, as well as to guarantee reliable, predictable performance and rapid machine setup and recovery. This article describes a beam line for bunch compression and recirculation, and beam switchyard accessing a diagnostic line for EUV lasing at 1 GeV beam energy. The footprint is modest, with 12 m compressive arc diameter and ˜20 m diagnostic line length. The design limits beam quality degradation due to CSR both in the compressor and in the switchyard. Advantages and drawbacks of two switchyard lines providing, respectively, off-line and on-line measurements are discussed. The entire design is scalable to different beam energies and charges.

Effects of laser fluence on silicon modification by four-beam laser interference

International Nuclear Information System (INIS)

Zhao, Le; Li, Dayou; Wang, Zuobin; Yue, Yong; Zhang, Jinjin; Yu, Miao; Li, Siwei

2015-01-01

This paper discusses the effects of laser fluence on silicon modification by four-beam laser interference. In this work, four-beam laser interference was used to pattern single crystal silicon wafers for the fabrication of surface structures, and the number of laser pulses was applied to the process in air. By controlling the parameters of laser irradiation, different shapes of silicon structures were fabricated. The results were obtained with the single laser fluence of 354 mJ/cm 2 , 495 mJ/cm 2 , and 637 mJ/cm 2 , the pulse repetition rate of 10 Hz, the laser exposure pulses of 30, 100, and 300, the laser wavelength of 1064 nm, and the pulse duration of 7–9 ns. The effects of the heat transfer and the radiation of laser interference plasma on silicon wafer surfaces were investigated. The equations of heat flow and radiation effects of laser plasma of interfering patterns in a four-beam laser interference distribution were proposed to describe their impacts on silicon wafer surfaces. The experimental results have shown that the laser fluence has to be properly selected for the fabrication of well-defined surface structures in a four-beam laser interference process. Laser interference patterns can directly fabricate different shape structures for their corresponding applications

Laser sintering of metal powders on top of sintered layers under multiple-line laser scanning

International Nuclear Information System (INIS)

Xiao Bin; Zhang Yuwen

2007-01-01

A three-dimensional numerical model for multiple-line sintering of loose powders on top of multiple sintered layers under the irradiation of a moving Gaussian laser beam is carried out. The overlaps between vertically deposited layers and adjacent lines which strengthen bonding are taken into account. The energy equation is formulated using the temperature transforming model and solved by the finite volume method. The effects of the number of the existing sintered layers, porosity and initial temperature coupled with the optimal combination laser intensity and scanning velocity are presented. The results show that the liquid pool moves slightly towards the negative scanning direction and the shape of the liquid pool becomes shallower with higher scanning velocity. A higher laser intensity is needed to achieve the required overlaps when the number of the existing sintered layers increases. Increasing porosity or initial temperature enhances the sintering process and thus less intensity is needed for the overlap requirement

Determination of electron beam parameters by means of laser-Compton scattering

Directory of Open Access Journals (Sweden)

K. Chouffani

2006-05-01

Full Text Available Laser-Compton scattering (LCS experiments were carried out at the Idaho Accelerator Center using the 5 ns (FWHM and 22 MeV electron beam. The electron beam was brought to an approximate head-on collision with a 29 MW, 7 ns (FWHM, 10 Hz Nd:YAG laser. Clear and narrow x-ray peaks resulting from the interaction of relativistic electrons with the Nd:YAG laser second harmonic line at 532 nm were observed. We have developed a relatively new method of using LCS as a nonintercepting electron beam monitor. Our method focused on the variation of the shape of the LCS spectrum rather than the LCS intensity as a function of the observation angle in order to extract the electron beam parameters at the interaction region. The electron beam parameters were determined by making simultaneous fits to spectra taken across the LCS x-ray cone. This scan method allowed us also to determine the variation of LCS x-ray peak energies and spectral widths as a function of the detector angles. Experimental data show that in addition to being viewed as a potential bright, tunable, and quasimonochromatic x-ray source, LCS can provide important information on the electron beam pulse length, direction, energy, angular and energy spread. Since the quality of LCS x-ray peaks, such as degree of monochromaticity, peak energy and flux, depends strongly on the electron beam parameters, LCS can therefore be viewed as an important nondestructive tool for electron beam diagnostics.

Active beam position stabilization of pulsed lasers for long-distance ion profile diagnostics at the Spallation Neutron Source (SNS).

Science.gov (United States)

Hardin, Robert A; Liu, Yun; Long, Cary; Aleksandrov, Alexander; Blokland, Willem

2011-02-14

A high peak-power Q-switched laser has been used to monitor the ion beam profiles in the superconducting linac at the Spallation Neutron Source (SNS). The laser beam suffers from position drift due to movement, vibration, or thermal effects on the optical components in the 250-meter long laser beam transport line. We have designed, bench-tested, and implemented a beam position stabilization system by using an Ethernet CMOS camera, computer image processing and analysis, and a piezo-driven mirror platform. The system can respond at frequencies up to 30 Hz with a high position detection accuracy. With the beam stabilization system, we have achieved a laser beam pointing stability within a range of 2 μrad (horizontal) to 4 μrad (vertical), corresponding to beam drifts of only 0.5 mm × 1 mm at the furthest measurement station located 250 meters away from the light source.

Laser induced fluorescence spectroscopy in atomic beams of radioactive nuclides

International Nuclear Information System (INIS)

Rebel, H.; Schatz, G.

1982-01-01

Measurements of the resonant scattering of light from CW tunable dye lasers, by a well collimated atomic beam, enable hyperfine splittings and optical isotope shifts to be determined with high precision and high sensitivity. Recent off-line atomic beam experiments with minute samples, comprising measurements with stable and unstable Ba, Ca and Pb isotopes are reviewed. The experimental methods and the analysis of the data are discussed. Information on the variation of the rms charge radii and on electromagnetic moments of nuclei in long isotopic chains is presented. (orig.) [de

The elettra beam line control system

International Nuclear Information System (INIS)

Mignacco, M.; Abrami, A.; Dequal, Z.

1994-01-01

Elettra is a third generation Synchrotron Light Source located in Trieste (Italy). It consists of a full energy linac injector and a storage ring with beam energies between 1.5 and 2 GeV. The facility is scheduled to be operational by end 1993. For the whole project 22 beam lines from insertion devices are foreseen, each of them is composed of a large number of measurement and controls instruments, most of them embedded in intelligent devices; in addition each beam line can be considered unique compared to the others, having been designed to provide a different kind of synchrotron radiation. This results in a large not homogenous environment where more than 200,000 physical points have to be controlled. A joint team composed of Softeco Sismat and Digital Equipment has developed a fully automated beam line control system able to give full remote controls, with different kind of access rights, to beam line users and beam line specialists as well as a full integration with experiment control systems. ((orig.))

Multi-focus beam shaping of high power multimode lasers

Science.gov (United States)

Laskin, Alexander; Volpp, Joerg; Laskin, Vadim; Ostrun, Aleksei

2017-08-01

Beam shaping of powerful multimode fiber lasers, fiber-coupled solid-state and diode lasers is of great importance for improvements of industrial laser applications. Welding, cladding with millimetre scale working spots benefit from "inverseGauss" intensity profiles; performance of thick metal sheet cutting, deep penetration welding can be enhanced when distributing the laser energy along the optical axis as more efficient usage of laser energy, higher edge quality and reduction of the heat affected zone can be achieved. Building of beam shaping optics for multimode lasers encounters physical limitations due to the low beam spatial coherence of multimode fiber-coupled lasers resulting in big Beam Parameter Products (BPP) or M² values. The laser radiation emerging from a multimode fiber presents a mixture of wavefronts. The fiber end can be considered as a light source which optical properties are intermediate between a Lambertian source and a single mode laser beam. Imaging of the fiber end, using a collimator and a focusing objective, is a robust and widely used beam delivery approach. Beam shaping solutions are suggested in form of optics combining fiber end imaging and geometrical separation of focused spots either perpendicular to or along the optical axis. Thus, energy of high power lasers is distributed among multiple foci. In order to provide reliable operation with multi-kW lasers and avoid damages the optics are designed as refractive elements with smooth optical surfaces. The paper presents descriptions of multi-focus optics as well as examples of intensity profile measurements of beam caustics and application results.

Spectral and spatial shaping of a laser-produced ion beam for radiation-biology experiments

Directory of Open Access Journals (Sweden)

L. Pommarel

2017-03-01

Full Text Available The study of radiation biology on laser-based accelerators is most interesting due to the unique irradiation conditions they can produce, in terms of peak current and duration of the irradiation. In this paper we present the implementation of a beam transport system to transport and shape the proton beam generated by laser-target interaction for in vitro irradiation of biological samples. A set of four permanent magnet quadrupoles is used to transport and focus the beam, efficiently shaping the spectrum and providing a large and relatively uniform irradiation surface. Real time, absolutely calibrated, dosimetry is installed on the beam line, to enable shot-to-shot control of dose deposition in the irradiated volume. Preliminary results of cell sample irradiation are presented to validate the robustness of the full system.

Plasma measurement by feedback-stabilized dual-beam laser interferometer

International Nuclear Information System (INIS)

Yasuda, Akio; Kawahata, Kazuo; Kanai, Yasubumi.

1982-03-01

The plasma density in a dynamic magneto arcjet is measured by a stabilized dual-beam laser interferometer proposed by the authors. The fringe shift for a 0.63 μm beam of He-Ne laser is used to stabilize the interferometer against the effect of mechanical vibration by means of a feedback controlled speaker coil, while the other beam of 3.39 μm, for which the effect of mechanical vibrations is excluded, is used to measure plasma density. Stability of --1/500 of one fringe for 0.63 μm is obtained during a long period for frequencies lower than a few Hertz. Stability for higher frequencies, which determines the accuracy of the present measurement, is limited to --1/30 of one fringe for 0.63 μm, which corresponds to --1/200 of one fringe and a line electron density of --1.5 x 10 14 cm - 2 for 3.39 μm, by acoustic noise picked up by the speaker coil. The advantage of this technique over the single-laser technique is that the frequency response of the interferometer extends down to zero frequency. Since the effect of the neutral gas background is practically reduced to zero, the present interferometer is to be applied advantageously to the diagnostics of the plasma produced in high pressure gases. (author)

Mjollnir Rotational Line Scan Diagnostics.

Science.gov (United States)

1981-05-19

using long cavity. M8 Removable Pellicle Beam Splitter for He-Ne Lineup Beam. Removed before HF or DF laser is turned on. 27 A 27 * A r of the chopper...three probe laser lines, however three lines were sequentially measured to verify the diagnostic equipment. Two of the three lines have been monitored

System for combining laser beams of diverse frequencies

International Nuclear Information System (INIS)

1980-01-01

A system is described for combining laser beams of different frequencies into a number of beams each comprising laser radiation having components of each of the different frequencies. The system can be used in laser isotope separation facilities. (U.K.)

Laser Compton polarimetry of proton beams

International Nuclear Information System (INIS)

Stillman, A.

1995-01-01

A need exists for non-destructive polarization measurements of the polarized proton beams in the AGS and, in the future, in RHIC. One way to make such measurements is to scatter photons from the polarized beams. Until now, such measurements were impossible because of the extremely low Compton scattering cross section from protons. Modern lasers now can provide enough photons per laser pulse not only to scatter from proton beams but also, at least in RHIC, to analyze their polarization

Staging laser plasma accelerators for increased beam energy

International Nuclear Information System (INIS)

Panasenko, Dmitriy; Shu, Anthony; Schroeder, Carl; Gonsalves, Anthony; Nakamura, Kei; Matlis, Nicholas; Cormier-Michel, Estelle; Plateau, Guillaume; Lin, Chen; Toth, Csaba; Geddes, Cameron; Esarey, Eric; Leemans, Wim

2008-01-01

Staging laser plasma accelerators is an efficient way of mitigating laser pump depletion in laser driven accelerators and necessary for reaching high energies with compact laser systems. The concept of staging includes coupling of additional laser energy and transporting the electron beam from one accelerating module to another. Due to laser damage threshold constraints, in-coupling laser energy with conventional optics requires distances between the accelerating modules of the order of 10m, resulting in decreased average accelerating gradient and complicated e-beam transport. In this paper we use basic scaling laws to show that the total length of future laser plasma accelerators will be determined by staging technology. We also propose using a liquid jet plasma mirror for in-coupling the laser beam and show that it has the potential to reduce distance between stages to the cm-scale.

Vaccum and beam diagnostic controls for ORIC beam lines

International Nuclear Information System (INIS)

Tatum, B.A.

1991-01-01

Vacuum and beam diagnostic equipment on beam lines from the Oak Ridge Isochronous Cyclotron, ORIC, is now controlled by a new dedicated system. The new system is based on an industrial programmable logic controller with an IBM AT personal computer providing control room operator interface. Expansion of this system requires minimal reconfiguration and programming, thus facilitating the construction of additional beam lines. Details of the implementation, operation, and performance of the system are discussed. 2 refs., 2 figs

Laser-plasma interaction with an adaptive optics wavefront-corrected laser beam

International Nuclear Information System (INIS)

Lewis, K.

2008-12-01

The propagation of an intense laser beam trough a preformed plasma is of particular interest in order to achieve laser inertial confinement fusion. Experiments carried out with a near-diffraction limited laser beam, producing a single hot spot interacting with the plasma, delivered new results, presented in this Ph.D. dissertation. In particular the first experimental observation of the filament instability confirms the numerous theoretical and numerical studies on the subject. Beam spreading and filament-ion thresholds are studied thanks to near-field and far-field images, with respect to laser intensity, time and space, and plasma transverse velocity. Same diagnostics have been applied to the stimulated Brillouin scattered light, enabling the first observation of the transverse Brillouin activity in the plasma. (author)

Electron-beam initiated HF lasers

International Nuclear Information System (INIS)

Gerber, R.A.; Patterson, E.L.

1975-01-01

Electron beams were used to ignite hydrogen/fluorine mixtures, producing laser energies up to 4.2 kJ, and giving hope that this approach may soon produce energy levels suitable for laser-fusion studies. (auth)

Laser beam trapping and propagation in cylindrical plasma columns

International Nuclear Information System (INIS)

Feit, M.D.; Fleck, J.A. Jr.

1976-01-01

An analysis of the scheme to heat magnetically confined plasma columns to kilovolt temperatures with a laser beam requires consideration of two propagation problems. The first question to be answered is whether stable beam trapping is possible. Since the laser beam creates its own density profile by heating the plasma, the propagation of the beam becomes a nonlinear phenomenon, but not necessarily a stable one. In addition, the electron density at a given time depends on the preceding history of both the medium and the laser pulse. A self-consistent time dependent treatment of the beam propagation and the medium hydrodynamics is consequently required to predict the behavior of the laser beam. Such calculations have been carried out and indicate that propagation of a laser beam in an initially uniform plasma can form a stable filament which alternately focuses and defocuses. An additional question that is discussed is whether diffractive losses associated with long propagation paths are significant

High-precision laser microcutting and laser microdrilling using diffractive beam-splitting and high-precision flexible beam alignment

Science.gov (United States)

Zibner, F.; Fornaroli, C.; Holtkamp, J.; Shachaf, Lior; Kaplan, Natan; Gillner, A.

2017-08-01

High-precision laser micro machining gains more importance in industrial applications every month. Optical systems like the helical optics offer highest quality together with controllable and adjustable drilling geometry, thus as taper angle, aspect ratio and heat effected zone. The helical optics is based on a rotating Dove-prism which is mounted in a hollow shaft engine together with other optical elements like wedge prisms and plane plates. Although the achieved quality can be interpreted as extremely high the low process efficiency is a main reason that this manufacturing technology has only limited demand within the industrial market. The objective of the research studies presented in this paper is to dramatically increase process efficiency as well as process flexibility. During the last years, the average power of commercial ultra-short pulsed laser sources has increased significantly. The efficient utilization of the high average laser power in the field of material processing requires an effective distribution of the laser power onto the work piece. One approach to increase the efficiency is the application of beam splitting devices to enable parallel processing. Multi beam processing is used to parallelize the fabrication of periodic structures as most application only require a partial amount of the emitted ultra-short pulsed laser power. In order to achieve highest flexibility while using multi beam processing the single beams are diverted and re-guided in a way that enables the opportunity to process with each partial beam on locally apart probes or semimanufactures.

Attenuation of laser power of a focused Gaussian beam during interaction between a laser and powder in coaxial laser cladding

International Nuclear Information System (INIS)

Liu Jichang; Li Lijun; Zhang Yuanzhong; Xie Xiaozhu

2005-01-01

The power of a focused laser beam with a Gaussian intensity profile attenuated by powder in coaxial laser cladding is investigated experimentally and theoretically, and its resolution model is developed. With some assumptions, it is concluded that the attenuation of laser power is an exponential function and is determined by the powder feed rate, particle moving speed, spraying angles and waist positions and diameters of the laser beam and powder flow, grain diameter and run of the laser beam through the powder flow. The attenuation of laser power increases with powder feed rate or run of laser beam through the powder flow. In the experiment presented, 300 W laser power from a focused Gaussian beam is attenuated by a coaxial powder flow. The experimental results agree well with the values calculated with the developed model

Measurement of the $\\beta$-asymmetry parameter in $^{35}$Ar decay with a laser polarized beam

CERN Multimedia

With this proposal we request beam time for the first two phases of a project that aims at measuring the $\\beta$-asymmetry parameter of the mirror $\\beta$-decay branch in $^{35}$Ar using an optically polarized Ar atom beam. The final goal of the experiment is to measure this parameter to a precision of 0.5%. This will allow the most precise determination of the V$_{ud}$ quark mixing matrix element from all the mirror transitions with an absolute uncertainty of 0.0007. The proposal will be presented in phases and we ask here 11 shifts (7 on-line + 4 off-line) for phase 1 and 15 shifts (6 on-line and 9 off-line) for phase 2. Phase 1 aims at establishing the optimal laser polarization scheme as well as the best implantation host for maintaining the polarization. Phase 2 aims at enhancing the beam polarization by removing the unpolarized part of the beam using re-ionization.

Beam shaping to provide round and square-shaped beams in optical systems of high-power lasers

Science.gov (United States)

Laskin, Alexander; Laskin, Vadim

2016-05-01

Optical systems of modern high-power lasers require control of irradiance distribution: round or square-shaped flat-top or super-Gaussian irradiance profiles are optimum for amplification in MOPA lasers and for thermal load management while pumping of crystals of solid-state ultra-short pulse lasers to control heat and minimize its impact on the laser power and beam quality while maximizing overall laser efficiency, variable profiles are also important in irradiating of photocathode of Free Electron lasers (FEL). It is suggested to solve the task of irradiance re-distribution using field mapping refractive beam shapers like piShaper. The operational principle of these devices presumes transformation of laser beam intensity from Gaussian to flat-top one with high flatness of output wavefront, saving of beam consistency, providing collimated output beam of low divergence, high transmittance, extended depth of field, negligible residual wave aberration, and achromatic design provides capability to work with ultra-short pulse lasers having broad spectrum. Using the same piShaper device it is possible to realize beams with flat-top, inverse Gauss or super Gauss irradiance distribution by simple variation of input beam diameter, and the beam shape can be round or square with soft edges. This paper will describe some design basics of refractive beam shapers of the field mapping type and optical layouts of their applying in optical systems of high-power lasers. Examples of real implementations and experimental results will be presented as well.

Laser beam-plasma plume interaction during laser welding

Science.gov (United States)

Hoffman, Jacek; Moscicki, Tomasz; Szymanski, Zygmunt

2003-10-01

Laser welding process is unstable because the keyhole wall performs oscillations which results in the oscillations of plasma plume over the keyhole mouth. The characteristic frequencies are equal to 0.5-4 kHz. Since plasma plume absorbs and refracts laser radiation, plasma oscillations modulate the laser beam before it reaches the workpiece. In this work temporary electron densities and temperatures are determined in the peaks of plasma bursts during welding with a continuous wave CO2 laser. It has been found that during strong bursts the plasma plume over the keyhole consists of metal vapour only, being not diluted by the shielding gas. As expected the values of electron density are about two times higher in peaks than their time-averaged values. Since the plasma absorption coefficient scales as ~N2e/T3/2 (for CO2 laser radiation) the results show that the power of the laser beam reaching the metal surface is modulated by the plasma plume oscillations. The attenuation factor equals 4-6% of the laser power but it is expected that it is doubled by the refraction effect. The results, together with the analysis of the colour pictures from streak camera, allow also interpretation of the dynamics of the plasma plume.

Multiple quasi-monoenergetic electron beams from laser-wakefield acceleration with spatially structured laser pulse

Energy Technology Data Exchange (ETDEWEB)

Ma, Y.; Li, M. H.; Li, Y. F.; Wang, J. G.; Tao, M. Z.; Han, Y. J.; Zhao, J. R.; Huang, K.; Yan, W. C.; Ma, J. L.; Li, Y. T. [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100080 (China); Chen, L. M., E-mail: lmchen@iphy.ac.cn [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100080 (China); Department of Physics and Astronomy and IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China); Li, D. Z. [Institute of High Energy Physics, CAS, Beijing 100049 (China); Chen, Z. Y. [Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, Sichuan 621999 (China); Sheng, Z. M. [Department of Physics and Astronomy and IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China); Department of Physics, Scottish Universities Physics Alliance, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Zhang, J. [Department of Physics and Astronomy and IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China)

2015-08-15

By adjusting the focus geometry of a spatially structured laser pulse, single, double, and treble quasi-monoenergetic electron beams were generated, respectively, in laser-wakefield acceleration. Single electron beam was produced as focusing the laser pulse to a single spot. While focusing the laser pulse to two spots that are approximately equal in energy and size and intense enough to form their own filaments, two electron beams were produced. Moreover, with a proper distance between those two focal spots, three electron beams emerged with a certain probability owing to the superposition of the diffractions of those two spots. The energy spectra of the multiple electron beams are quasi-monoenergetic, which are different from that of the large energy spread beams produced due to the longitudinal multiple-injection in the single bubble.

The Nike electron-beam-pumped KrF laser amplifiers

International Nuclear Information System (INIS)

Sethian, J.D.; Pawley, C.J.; Obenschain, S.P.

1997-01-01

Nike is a recently completed multikilojoule krypton-fluoride (KrF) laser that has been built to study the physics of direct-drive inertial confinement fusion. The two final amplifiers of the Nike laser are both electron-beam-pumped systems. This paper describes these two amplifiers, with an emphasis on the pulsed power. The smaller of the two has a 20 x 20 cm aperture, and produces an output laser beam energy in excess of 100 J. This 20 cm Amplifier uses a single 12 kJ Marx generator to inject two 300 kV, 75 kA, 140 ns flat-top electron beams into opposite sides of the laser cell. The larger amplifier in Nike has a 60 x 60 cm aperture, and amplifies the laser beam up to 5 kJ. This 60 cm amplifier has two independent electron beam systems. Each system has a 170 kJ Marx generator that produces a 670 kV, 540 kA, 240 ns flat-top electron beam. Both amplifiers are complete, fully integrated into the laser, meet the Nike system requirements, and are used routinely for laser-target experiments

A laser beam quality definition based on induced temperature rise.

Science.gov (United States)

Miller, Harold C

2012-12-17

Laser beam quality metrics like M(2) can be used to describe the spot sizes and propagation behavior of a wide variety of non-ideal laser beams. However, for beams that have been diffracted by limiting apertures in the near-field, or those with unusual near-field profiles, the conventional metrics can lead to an inconsistent or incomplete description of far-field performance. This paper motivates an alternative laser beam quality definition that can be used with any beam. The approach uses a consideration of the intrinsic ability of a laser beam profile to heat a material. Comparisons are made with conventional beam quality metrics. An analysis on an asymmetric Gaussian beam is used to establish a connection with the invariant beam propagation ratio.

Laser streaming: Turning a laser beam into a flow of liquid.

Science.gov (United States)

Wang, Yanan; Zhang, Qiuhui; Zhu, Zhuan; Lin, Feng; Deng, Jiangdong; Ku, Geng; Dong, Suchuan; Song, Shuo; Alam, Md Kamrul; Liu, Dong; Wang, Zhiming; Bao, Jiming

2017-09-01

Transforming a laser beam into a mass flow has been a challenge both scientifically and technologically. We report the discovery of a new optofluidic principle and demonstrate the generation of a steady-state water flow by a pulsed laser beam through a glass window. To generate a flow or stream in the same path as the refracted laser beam in pure water from an arbitrary spot on the window, we first fill a glass cuvette with an aqueous solution of Au nanoparticles. A flow will emerge from the focused laser spot on the window after the laser is turned on for a few to tens of minutes; the flow remains after the colloidal solution is completely replaced by pure water. Microscopically, this transformation is made possible by an underlying plasmonic nanoparticle-decorated cavity, which is self-fabricated on the glass by nanoparticle-assisted laser etching and exhibits size and shape uniquely tailored to the incident beam profile. Hydrophone signals indicate that the flow is driven via acoustic streaming by a long-lasting ultrasound wave that is resonantly generated by the laser and the cavity through the photoacoustic effect. The principle of this light-driven flow via ultrasound, that is, photoacoustic streaming by coupling photoacoustics to acoustic streaming, is general and can be applied to any liquid, opening up new research and applications in optofluidics as well as traditional photoacoustics and acoustic streaming.

High energy gain electron beam acceleration by 100TW laser

International Nuclear Information System (INIS)

Kotaki, Hideyuki; Kando, Masaki; Kondo, Shuji; Hosokai, Tomonao; Kanazawa, Shuhei; Yokoyama, Takashi; Matoba, Toru; Nakajima, Kazuhisa

2001-01-01

A laser wakefield acceleration experiment using a 100TW laser is planed at JAERI-Kansai. High quality and short pulse electron beams are necessary to accelerate the electron beam by the laser. Electron beam - laser synchronization is also necessary. A microtron with a photocathode rf-gun was prepared as a high quality electron injector. The quantum efficiency (QE) of the photocathode of 2x10 -5 was obtained. A charge of 100pC from the microtron was measured. The emittance and pulse width of the electron beam was 6π mm-mrad and 10ps, respectively. In order to produce a short pulse electron beam, and to synchronize between the electron beam and the laser pulse, an inverse free electron laser (IFEL) is planned. One of problems of LWFA is the short acceleration length. In order to overcome the problem, a Z-pinch plasma waveguide will be prepared as a laser wakefield acceleration tube for 1 GeV acceleration. (author)

Laser beam propagation in atmospheric turbulence

Science.gov (United States)

Murty, S. S. R.

1979-01-01

The optical effects of atmospheric turbulence on the propagation of low power laser beams are reviewed in this paper. The optical effects are produced by the temperature fluctuations which result in fluctuations of the refractive index of air. The commonly-used models of index-of-refraction fluctuations are presented. Laser beams experience fluctuations of beam size, beam position, and intensity distribution within the beam due to refractive turbulence. Some of the observed effects are qualitatively explained by treating the turbulent atmosphere as a collection of moving gaseous lenses of various sizes. Analytical results and experimental verifications of the variance, covariance and probability distribution of intensity fluctuations in weak turbulence are presented. For stronger turbulence, a saturation of the optical scintillations is observed. The saturation of scintillations involves a progressive break-up of the beam into multiple patches; the beam loses some of its lateral coherence. Heterodyne systems operating in a turbulent atmosphere experience a loss of heterodyne signal due to the destruction of coherence.

Free-electron laser beam

International Nuclear Information System (INIS)

Minehara, Eisuke

2003-01-01

The principle and history of free-electron laser (FEL), first evidenced in 1977, the relationship between FEL wavelength and output power, the high-power FEL driven by the superconducting linac, the X-ray FEL by the linac, and the medical use are described. FEL is the vacuum oscillator tube and essentially composed from the high-energy linac, undulator and light-resonator. It utilizes free electrons in the vacuum to generate the beam with wavelength ranging from microwave to gamma ray. The first high-power FEL developed in Japanese Atomic Energy Research Institute (JAERI) is based on the development of superconducting linac for oscillating the highest power beam. In the medical field, applications to excise brain tumors (in US) and to reconstruct experimentally blood vessels in the pig heart (in Gunma University) by lasing and laser coagulator are in progress with examinations to remove intra-vascular cholesterol mass by irradiation of 5.7μm FEL beam. Cancer cells are considered diagnosed by FEL beam of far-infrared-THz range. The FEL beam CT is expected to have a wide variety of application without the radiation exposure and its resolution is equal or superior to that of usual imaging techniques. (N.I.)

Propagation of highly aberrated laser beams in nonquadratic plasma waveguides

International Nuclear Information System (INIS)

Feit, M.D.; Fleck, J.A. Jr.; Morris, J.R.

1977-01-01

The propagation of a laser beam in a plasma column several meters long with a realistic electron density distribution is examined. The electron density distribution is based on laser-beam heating at z=0, but is otherwise uncoupled to the laser beam. The aberrated nature of the resulting lenslike medium leads to essentially aperiodic beam properties, which contrast with the completely periodic properties of Gaussian beams propagating in quadratic lenslike media. The beam is nonetheless stably trapped. These aberrated-beam properties also help to stabilize the beam against axial variations in refractive index

Design of Extended Depth-of-Focus Laser Beams Using Orthogonal Beam Expansions

Directory of Open Access Journals (Sweden)

Leonard Bergstein

2005-06-01

Full Text Available Laser beams with extended depth of focus have many practical applications, such as scanning printed bar codes. Previous work has concentrated on synthesizing such beams by approximating the nondiffracting Bessel beam solution to the wave equation. In this paper, we introduce an alternate novel synthesis method that is based on maintaining a minimum MTF value (contrast over the largest possible distance. To achieve this, the coefficients of an orthogonal beam expansion are sequentially optimized to this criterion. One of the main advantages of this method is that it can be easily generalized to noncircularly symmetrical beams by the appropriate choice of the beam expansion basis functions. This approach is found to be very useful for applications that involve scanning of the laser beam.

Self-focusing of laser beam crossing a laser plasma

International Nuclear Information System (INIS)

Bakos, J.S.; Foeldes, I.B.; Ignacz, P.N.; Soerlei, Zs.

1983-03-01

A crossed-beam experiment was performed to clarify the mechanism of self-focusing in a laser produced spark. The plasma was created by one beam and self-focusing was observed in the weak probe beam which crossed the plasma. Experimental results show that the cause of self-focusing is the nonuniform heating mechanism. (author)

Beam line design for a low energy electron beam

International Nuclear Information System (INIS)

Arvind Kumar; Mahadevan, S.

2002-01-01

The design of a beam line for transport of a 70 keV electron beam from a thermionic gun to the Plane Wave Transformer (PWT) linac incorporating two solenoid magnets, a beam profile monitor and drift sections is presented. We used beam dynamics codes EGUN, PARMELA and compare simulated results with analytical calculations. (author)

Vacuum laser acceleration using a radially polarized CO sub 2 laser beam

CERN Document Server

Liu, Y; He, P

1999-01-01

Utilizing the high-power, radially polarized CO sub 2 laser and high-quality electron beam at the Brookhaven Accelerator Test Facility, a vacuum laser acceleration scheme is proposed. In this scheme, optics configuration is simple, a small focused beam spot size can be easily maintained, and optical damage becomes less important. At least 0.5 GeV/m acceleration gradient is achievable by 1 TW laser power.

Optodynamics: dynamic aspects of laser beam-surface interaction

International Nuclear Information System (INIS)

Možina, J; Diaci, J

2012-01-01

This paper presents a synthesis of the results of our original research in the area of laser-material interaction and pulsed laser material processing with a special emphasis on the dynamic aspects of laser beam-surface interaction, which include the links between the laser material removal and the resulting material motion. In view of laser material processing, a laser beam is not only considered as a tool but also as a generator of information about the material transformation. The information is retained and conveyed by different kinds of optically induced mechanical waves. Several generation/detection schemes have been developed to extract this information, especially in the field of non-destructive material evaluation. Blast and acoustic waves, which propagate in the air surrounding the work-piece, have been studied using microphone detection as well as various setups of the laser beam deflection probe. Stress waves propagating through the work-piece have been studied using piezoelectric transducers and laser interferometers.

Laser cutting system in bridge fabricating line; Kyoryo seisaku line ni okeru laser no setsudan system

Energy Technology Data Exchange (ETDEWEB)

Kitaguchi, Y.; Yokotani, K. [Hitachi Zosen Corp., Osaka (Japan)

1994-11-01

This paper describes the laser cutting system established at a new advanced plant that was constructed by Hitachi Shipbuilding and Engineering Co., Ltd. in 1993. At the plant, the cutting line consists of four NC cutting lines: the plasma cutting machine, gas cutting machine, frame planer, and laser cutting machine. The laser cutting machine is used to cut complex shapes of relatively thin (6 - 16 mm) materials with high accuracy. The machine consists of a 3 kW CO2 laser oscillator mounted gantry type NC cutter and a slat conveyor of about 30 m long, with the maximum cutting width of 3.6 m. The NC cutting machine is provided with the automatic printing function using NC data, marking function, scheduled operation function, steel plate detector, and coordinate rotation function, etc. These functions enable unattended operation of the machine to cut multiple materials. This NC laser cutting line has the same performance data collection function for data during the operating time as other production lines. Therefore, the NC laser cutting line can be subjected to the realtime centralized control together with the other lines. All these technologies have provided high accuracy and efficiency for production as well as an environment in which many female operators can successfully work. 10 figs., 4 tabs.

CO2 laser direct writing of silver lines on epoxy resin from solid film

International Nuclear Information System (INIS)

Liu, J.G.; Chen, C.H.; Zheng, J.S.; Huang, J.Y.

2005-01-01

A technique of CO 2 laser direct writing from solid film was proposed in this paper. Patterns of silver lines were locally deposited on the non-conductive substrate using a preset layer of silver compound solid film, which was irradiated by focused CO 2 laser beam. The deposits were analyzed by XPS and EPMA. Results showed that metallic silver was dominant with an even distribution on the surface of the substrate, and part of the deposited silver had diffused into the substrate interior. The deposits had catalytic activity for the further electroless copper plating and had strong adhesion to the substrate. At last, the deposition mechanism and the dependence of the width of silver lines on the laser power and scan speed were roughly explored

Multiquantum well beam-steering device for laser satellite communication

Science.gov (United States)

Lahat, Roee; Levy, Itamar; Shlomi, Arnon

2002-01-01

With the increasing interest in laser satellite communications, new methods are sought to solve the existing problems of accurate and rapid laser beam deflection. Current solutions in the form of galvanometers or piezo fast steering mirrors with one or two degrees of freedom are bulky, power-consuming and slow. The Multi-Quantum Well (MQW) is a semiconductor device with unique potential to steer laser beams without any moving parts. We have conducted a preliminary evaluation of the potential application of the MQW as a laser beam-steering device for laser satellite communication, examining the performance of critical parameters for this type of communications.

Model for Atmospheric Propagation of Spatially Combined Laser Beams

Science.gov (United States)

2016-09-01

NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS MODEL FOR ATMOSPHERIC PROPAGATION OF SPATIALLY COMBINED LASER BEAMS by Kum Leong Lee September...MODEL FOR ATMOSPHERIC PROPAGATION OF SPATIALLY COMBINED LASER BEAMS 5. FUNDING NUMBERS 6. AUTHOR(S) Kum Leong Lee 7. PERFORMING ORGANIZATION NAME(S) AND...BLANK ii Approved for public release. Distribution is unlimited. MODEL FOR ATMOSPHERIC PROPAGATION OF SPATIALLY COMBINED LASER BEAMS Kum Leong Lee

Beam splash effects on ATLAS silicon microstrip detectors evaluated using 1-w Nd YAG laser

CERN Document Server

Hara, K; Kohriki, T; Kuwano, T; Moorhead, G F; Terada, S; Unno, Y

2005-01-01

On an incident of accelerator beam loss, the tracking detector located close to the beam line is subjected to receive intensive radiation in a short period. We used a 1-W focused Nd: YAG laser and simulated the effects on the ATLAS microstrip detector. The laser corresponds to intensity of up to 1 multiplied by 109mips/pulse with a pulse width of about 10 ns. We observed breaks on Al strips on extreme conditions, depending on the laser intensity and bias voltage applied to the silicon sensor. The break can be interpreted as the oxide breakdown due to a large voltage locally created across the oxide by the intensive signal charges. The robustness of the Semiconductor Tracker (SCT) module including readout ASICs is also evaluated.

The Beam Characteristics of High Power Diode Laser Stack

Science.gov (United States)

Gu, Yuanyuan; Fu, Yueming; Lu, Hui; Cui, Yan

2018-03-01

Direct diode lasers have some of the most attractive features of any laser. They are very efficient, compact, wavelength versatile, low cost, and highly reliable. However, the full utilization of direct diode lasers has yet to be realized. However, the poor quality of diode laser beam itself, directly affect its application ranges, in order to better use of diode laser stack, need a proper correction of optical system, which requires accurate understanding of the diode laser beam characteristics. Diode laser could make it possible to establish the practical application because of rectangular beam patterns which are suitable to make fine bead with less power. Therefore diode laser cladding will open a new field of repairing for the damaged machinery parts which must contribute to recycling of the used machines and saving of cost.

Laser scanning confocal microscope with programmable amplitude, phase, and polarization of the illumination beam.

Science.gov (United States)

Boruah, B R; Neil, M A A

2009-01-01

We describe the design and construction of a laser scanning confocal microscope with programmable beam forming optics. The amplitude, phase, and polarization of the laser beam used in the microscope can be controlled in real time with the help of a liquid crystal spatial light modulator, acting as a computer generated hologram, in conjunction with a polarizing beam splitter and two right angled prisms assembly. Two scan mirrors, comprising an on-axis fast moving scan mirror for line scanning and an off-axis slow moving scan mirror for frame scanning, configured in a way to minimize the movement of the scanned beam over the pupil plane of the microscope objective, form the XY scan unit. The confocal system, that incorporates the programmable beam forming unit and the scan unit, has been implemented to image in both reflected and fluorescence light from the specimen. Efficiency of the system to programmably generate custom defined vector beams has been demonstrated by generating a bottle structured focal volume, which in fact is the overlap of two cross polarized beams, that can simultaneously improve both the lateral and axial resolutions if used as the de-excitation beam in a stimulated emission depletion confocal microscope.

High-power direct diode laser output by spectral beam combining

Science.gov (United States)

Tan, Hao; Meng, Huicheng; Ruan, Xu; Du, Weichuan; Wang, Zhao

2018-03-01

We demonstrate a spectral beam combining scheme based on multiple mini-bar stacks, which have more diode laser combining elements, to increase the combined diode laser power and realize equal beam quality in both the fast and slow axes. A spectral beam combining diode laser output of 1130 W is achieved with an operating current of 75 A. When a 9.6 X de-magnifying telescope is introduced between the output mirror and the diffraction grating, to restrain cross-talk among diode laser emitters, a 710 W spectral beam combining diode laser output is achieved at the operating current of 70 A, and the beam quality on the fast and slow axes of the combined beam is about 7.5 mm mrad and 7.3 mm mrad respectively. The power reduction is caused by the existence of a couple resonator between the rear facet of the diode laser and the fast axis collimation lens, and it should be eliminated by using diode laser chips with higher front facet transmission efficiency and a fast axis collimation lens with lower residual reflectivity.

The KAERI laser facility with temporal laser beam shaping for application's user

International Nuclear Information System (INIS)

Hong, Sung Ki; Kim, Min Suk; Kim, Young Won; Ko, Kwanghoon; Lim, Changhwan; Seo, Young Seok

2008-01-01

The Korea Atomic Energy Research Institute(KAERI)has been developed a high energy Nd:Glass laser facility(KLF)for fast ignition research and high energy physics applications at early 2008. Now, we are researching the temporal laser beam shaping for application's user. The temporal laser beam shaping has been applied to a number of industrial applications. The KLF beam shaping system with fiber based consists of two electro optic modulator with DC bias using a Mach Zehnder interferometer, an arbitrary electronic waveform generator, a continuous wavelength fiber laser source, a fiber based pulse amplification system and DC bias source to generate temporally shaped pulses with a high extinction ratio and high resolution. RF signal waveform user defined by an arbitrary electronic waveform generator is only connected to one electro optic modulator. DC bias source with auto feed back or manual controller is connected both two electro optic modulators. Emitting laser light from a continuous wavelength fiber laser source is modulated to meet a user defined laser pulse with a high extinction ratio by two electro optic modulators. Experimental results are shown in Fig.1. Figure 1(a)shows two programmed waveforms with the signal width 10ns in an arbitrary electronic waveform generator. Figure 1(b)shows output laser pulses with sub mJ energy from amplification results of the KLF beam shaping system which can control the pulse width ranges from 400ps to sub us

Influence of laser beam profiles on received power fluctuation

Science.gov (United States)

Dordova, Lucie; Diblik, Jan

2011-09-01

Gaussian beam is very often used for the transmission of information in optical wireless links. The usage of this optical beam has its advantages and, of course, disadvantages. This work focuses on possibilities of using laser beams with different distribution of optical intensity - Top Hat beam. Creation of the optical beam with selected optical intensity profile will be briefly described. Optical beams will propagate through the "clear" and stationary atmosphere in the experimental part of this work. These results will be compared with the data obtained after a laser beam is passed through the turbulent and attenuated atmosphere. We will use an ultrasound fog generator for laser beam attenuation testing. To create the turbulence, infra radiators will be applied. Particular results obtained from different atmospheric conditions will be compared and using different types of optical beams will be assessed.

Doppler-shifted neutral beam line shape and beam transmission

International Nuclear Information System (INIS)

Kamperschroer, J.H.; Grisham, L.R.; Kokatnur, N.; Lagin, L.J.; Newman, R.A.; O'Connor, T.E.; Stevenson, T.N.; von Halle, A.

1994-04-01

Analysis of Doppler-shifted Balmer-α line emission from the TFTR neutral beam injection systems has revealed that the line shape is well approximated by the sum of two Gaussians, or, alternatively, by a Lorentzian. For the sum of two Gaussians, the broad portion of the distribution contains 40% of the beam power and has a divergence five times that of the narrow part. Assuming a narrow 1/e- divergence of 1.3 degrees (based on fits to the beam shape on the calorimeter), the broad part has a divergence of 6.9 degrees. The entire line shape is also well approximated by a Lorentzian with a half-maximum divergence of 0.9 degrees. Up to now, fusion neutral beam modelers have assumed a single Gaussian velocity distribution, at the extraction plane, in each direction perpendicular to beam propagation. This predicts a beam transmission efficiency from the ion source to the calorimeter of 97%. Waterflow calorimetry data, however, yield a transmission efficiency of ∼75%, a value in rough agreement with predictions of the Gaussian or Lorentzian models presented here. The broad wing of the two Gaussian distribution also accurately predicts the loss in the neutralizer. An average angle of incidence for beam loss at the exit of the neutralizer is 2.2 degrees, rather than the 4.95 degrees subtended by the center of the ion source. This average angle of incidence, which is used in computing power densities on collimators, is shown to be a function of beam divergence

Research on applications of rectangular beam in micro laser propulsion

International Nuclear Information System (INIS)

Jiao, L.; Cai, J.; Ma, H.H.; Li, G.X.; Li, L.; Shen, Z.W.; Tang, Z.P.

2014-01-01

Highlights: • Diode laser bar of 808 nm is introduced into the micro laser propulsion field. • Double base propellant (DBP) coating with BOPP substrate was obtained. • The combination of laser power and energy decides the propulsion performance. • The new rectangular beam prefers to produce higher impulse. - Abstract: Micro laser propulsion is a new technology with brilliant future. In order to reduce the thruster mass and volume further, laser bar is introduced into the micro laser propulsion field. A new kind of 220 × 20 μm rectangular beam of 808 nm was obtained by oval lens compressing the light of diode at fast axes and slow axes. The effect of laser power, energy and coating thickness of double base propellant on propulsion performance was studied. Propulsion performance of double base propellant under static and dynamic mode shows some different characters. Compared to round beam, the new beam prefers to produce higher impulse. Ablation efficiency of DBP shows better performance in short laser duration. The combination of power density and energy density decides the laser propulsion performance. The new rectangular beam is appropriate for millisecond micro-laser propulsion

SLIA beam line design

International Nuclear Information System (INIS)

Petillo, J.; Chernin, D.; Kostas, C.; Mondelli, A.

1990-01-01

The Spiral Line Induction Accelerator (SLIA) is a multi-kiloampere compact electron accelerator. It uses linear induction accelerator modules on the straight sections of a racetrack spiral, with strong-focusing bends to recirculate the electrons. The strong focusing is provided by stellarator windings on the bends. Stellarator coils are used to provide the strong focusing on the bends. The matching of the electron beam from a diode through a series of accelerator modules and stellarator bends is a major issue in the design of this accelerator. The beam line design for a proof-of-concept SLIA experiment (10 kA, 7 MeV) to be carried out at Pulse Sciences, Inc. will be presented. The design will demonstrate beam matching from element to element in the focusing system, the design of an achromatic bend, and the requirements for avoiding collective instabilities

Beam transport optics for high-power laser systems

International Nuclear Information System (INIS)

Taylor, J.R.

1995-01-01

Beam transport optics receive output energy from the laser cavity and deliver it to the work site. Depending on the application, this may require a few simple elements or large complex systems. Collection of the laser energy depends on the spatial and temporal energy distribution as well as the wavelength and polarization of the laser cavity and output coupler. Transport optics can perform a variety of functions, including beam formatting, frequency doubling, and distribution to one or more work sites while maintaining or even improving the beam quality. The beam may be delivered to work sites as focused spots or images, projected to distant targets, or propagated through various media for sensing or photochemical processing. Design may involve optical modeling of the system, including diffraction effects and thermal management. A Gaussian beam profile is often used for convenience in modeling. When deviations from this ideal profile need to be considered, it is necessary to characterize the laser beam in detail. Design of the transport system requires understanding of the interaction of the laser energy with optical materials and components. Practical considerations include mounting the optics without stress and with the stability suitable for the intended application. Requirements for beam direction, stability, size, shape, and quality dictate the design approach for each specific situation. Attention also must be given to reliability, environmental, and commercial requirements. Damage to optics in high-power laser systems is a common concern. Environmental problems such as atmospheric turbulence, contamination by dust or vapor from the work site or other sources, or absorption of water vapor can directly degrade beam quality. Other potentially significant optical performance effects may result from instability and aging of the optics, temperature, humidity, pressure, transmitted vibration, and contamination from the work site or other sources

Implementation of EPICS based Control System for Radioisotope Beam line

Energy Technology Data Exchange (ETDEWEB)

Kim, Jae-Ha; Ahn, Tae-Sung; Song, Young-Gi; Kwon, Hyeok-Jung; Cho, Yong-Sub [Korea Atomic Energy Research Institute, Gyeongju (Korea, Republic of)

2015-10-15

Korea Mult-purpose Accelerator Complex (KOMAC) has been operating 100 MeV proton linear accelerator . For operating 100 MeV linac, various control system has been implemented such as vacuum, power supply, RCCS and etc. KOMAC is operating two beam lines so that clients can use 100 MeV proton beam for their experiment. KOMAC sends beam to beam line and target room using two dipole magnets and several quadrupole magnets. As demand for experiments and Radius Isotope using beam is increased, another beam line is under construction and RI beam line control system is need. To synchronize with KOMAC control system, RI beam line control system is based on Experimental Physics and Industrial control System (EPICS) software. The beam is transported to RI beam line to control magnet power supply and vacuum. Implementation of RI beam line control system is presented and some preliminary results are reported. The base RI beam line control system is implemented. It can control beam direction and vacuum. Comparing archived data and current data, RI beam line and control system will be improved. In the future, scroll pump and gate control system will be implemented using programmable logic controller PLC. RI beam interlock sequence will be added to KOMAC interlock system to protect linac.

Method of laser beam coding for control systems

Science.gov (United States)

Pałys, Tomasz; Arciuch, Artur; Walczak, Andrzej; Murawski, Krzysztof

2017-08-01

The article presents the method of encoding a laser beam for control systems. The experiments were performed using a red laser emitting source with a wavelength of λ = 650 nm and a power of P ≍ 3 mW. The aim of the study was to develop methods of modulation and demodulation of the laser beam. Results of research, in which we determined the effect of selected camera parameters, such as image resolution, number of frames per second on the result of demodulation of optical signal, is also shown in the paper. The experiments showed that the adopted coding method provides sufficient information encoded in a single laser beam (36 codes with the effectiveness of decoding at 99.9%).

Laser Beam delivering and shaping device for transfer of organic film

International Nuclear Information System (INIS)

Lee, Kangin; Kwon, Jin Hyuk; Yi, Jonghoon

2008-01-01

The laser based organic material transfer methods are developed by several groups for OLED (organic light emitting diode)fabrication. Well developed laser based methods are LITI (Laser Induced Thermal Imaging)and LIPS (Laser Induced Pattern wise Sublimation). These methods are proved to be suitable for large OLED panel fabrication. At an early stage of development, TEM"00"mode Nd:YAG laser was used for pattering organic material. The focused focused Nd:YAG laser beam generated heat in the film and the heat caused expansion of organic material coated layer. The organic film on the layer is transferred to the display panel due to pressure exerted on the display panel by the layer. Recently developed system prefers to employ a diode laser with wavelength of 800nm. Diode laser is cheaper and smaller photon source compared with the Nd:YAG laser. In this work, we use Nd doped fiber laser (wavelength=1070nm, power=10W)because the laser has stable output and well defined Gaussian beam profile compared with diode laser. We also employed fiber coupled diode laser (808nm)because it also has well defined beam distribution. In laser methods, spatially shaped beam is required for clean and sharp transfer. There are several methods for the beam shaping such as aspheric lens, diffractive optical elements, and micro lens array etc. We found that Gaussian beam can be shaped to a square hat like beam just by using simple commercial spherical lens set

Propagation and stability characteristics of a 500-m-long laser-based fiducial line for high-precision alignment of long-distance linear accelerators.

Science.gov (United States)

Suwada, Tsuyoshi; Satoh, Masanori; Telada, Souichi; Minoshima, Kaoru

2013-09-01

A laser-based alignment system with a He-Ne laser has been newly developed in order to precisely align accelerator units at the KEKB injector linac. The laser beam was first implemented as a 500-m-long fiducial straight line for alignment measurements. We experimentally investigated the propagation and stability characteristics of the laser beam passing through laser pipes in vacuum. The pointing stability at the last fiducial point was successfully obtained with the transverse displacements of ±40 μm level in one standard deviation by applying a feedback control. This pointing stability corresponds to an angle of ±0.08 μrad. This report contains a detailed description of the experimental investigation for the propagation and stability characteristics of the laser beam in the laser-based alignment system for long-distance linear accelerators.

Laser beam diagnostics for metalworking applications

International Nuclear Information System (INIS)

Ramos, T.J.; Lingenfelter, A.C.

1984-01-01

The Materials Fabrication Division of Lawrence Livermore National Laboratory (LLNL) has three pulsed Nd-YAG lasers dedicated to metalworking. The units are used in a job shop primarily for welding. They also have a number of applications requiring cutting and drilling capability. Each of these metalworking operations requires somewhat different laser beam characteristics. As most investigators have found, the mode of the laser beam and the mode stability are the key variables which must be controlled if optimum results are to be achieved. The authors use several techniques to observe and measure these variables, i.e. Charge Couple Device (CCD) Camera, Thermal Image Plate and thermal-sensitive paper

High-quality laser-accelerated ion beams for medical applications

Energy Technology Data Exchange (ETDEWEB)

Harman, Zoltan; Keitel, Christoph H. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Salamin, Yousef I. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); American University of Sharjah (United Arab Emirates)

2009-07-01

Cancer radiation therapy requires accelerated ion beams of high energy sharpness and a narrow spatial profile. As shown recently, linearly and radially polarized, tightly focused and thus extremely strong laser beams should permit the direct acceleration of light atomic nuclei up to energies that may offer the potentiality for medical applications. Radially polarized beams have better emittance than their linearly polarized counterparts. We put forward the direct laser acceleration of ions, once the refocusing of ion beams by external fields is solved or radially polarized laser pulses of sufficient power can be generated.

Monitoring the beam flux in molecular beam epitaxy using laser multiphoton ionization

International Nuclear Information System (INIS)

Chien, R.; Sogard, M.R.

1990-01-01

In this paper, we will describe a method using laser nonresonant multiphoton ionization to measure beam flux in molecular beam epitaxy (MBE) systems. The results were obtained in a test chamber where a focused excimer laser beam was used to photoionize a small fraction of the atomic and molecular beams. The constituents of the beams were identified by a time-of-flight mass spectrometer. Ion signal strength was found to be directly correlated to the temperature of the atomic beam oven. Good stability and sensitivity on gallium, aluminum, and silicon atomic beams was demonstrated. Arsenic was also detected. We demonstrated very sensitive detection of contaminant atomic and molecular constituents of our system. We have also detected the presence of short-term fluctuations in the gallium flux from an effusion source. These fluctuations, previously suspected, can be in excess of ±10%

Synchronous characterization of semiconductor microcavity laser beam.

Science.gov (United States)

Wang, T; Lippi, G L

2015-06-01

We report on a high-resolution double-channel imaging method used to synchronously map the intensity- and optical-frequency-distribution of a laser beam in the plane orthogonal to the propagation direction. The synchronous measurement allows us to show that the laser frequency is an inhomogeneous distribution below threshold, but that it becomes homogeneous across the fundamental Gaussian mode above threshold. The beam's tails deviations from the Gaussian shape, however, are accompanied by sizeable fluctuations in the laser wavelength, possibly deriving from manufacturing details and from the influence of spontaneous emission in the very low intensity wings. In addition to the synchronous spatial characterization, a temporal analysis at any given point in the beam cross section is carried out. Using this method, the beam homogeneity and spatial shape, energy density, energy center, and the defects-related spectrum can also be extracted from these high-resolution pictures.

Feedback-stabilized dual-beam laser interferometer for plasma measurements

International Nuclear Information System (INIS)

Yasuda, A.; Kanai, Y.; Kusunoki, J.; Kawahata, K.; Takeda, S.

1980-01-01

A stabilized laser interferometer is proposed with two beams as the light source. The fringe shift for a 0.63 μm beam of a He--Ne laser is used to stabilize the interferometer against the effect of mechanical vibrations via a feedback controlled speaker coil, while another beam of 3.39 μm, for which consequently the effect of the mechanical vibrations is excluded, is used to measure the plasma density. A stability of approx.1/500 of one fringe for 0.63 μm is obtained during a long period for frequencies lower than a few Hz. The stability for higher frequencies is limited to approx.1/30 of one fringe for 0.63 μm, which correspondes to approx.1/200 of one fringe for 3.39 μm, by the acoustic noise picked up by the speaker coil. Furthermore, the total accuracy is limited by the detector noise to approx.1/60 of one fringe for 3.39 μm, which corresponds to a line electron density of approx.5 x 10 14 cm -2 . The detector noise may be reduced by cooling the detector. The advantage of this technique over the single-laser technique is that the frequency response of the interferometer extends down to zero frequency. The interferometer is tested with the measurement of a plasma in a dynamic magnetic arcjet. Since the effect of the neutral gas background is reduced in the present interferometer, the application has an advantage for the diagnostics of plasmas produced in high pressure gases

Multimode laser beam analyzer instrument using electrically programmable optics.

Science.gov (United States)

Marraccini, Philip J; Riza, Nabeel A

2011-12-01

Presented is a novel design of a multimode laser beam analyzer using a digital micromirror device (DMD) and an electronically controlled variable focus lens (ECVFL) that serve as the digital and analog agile optics, respectively. The proposed analyzer is a broadband laser characterization instrument that uses the agile optics to smartly direct light to the required point photodetectors to enable beam measurements of minimum beam waist size, minimum waist location, divergence, and the beam propagation parameter M(2). Experimental results successfully demonstrate these measurements for a 500 mW multimode test laser beam with a wavelength of 532 nm. The minimum beam waist, divergence, and M(2) experimental results for the test laser are found to be 257.61 μm, 2.103 mrad, 1.600 and 326.67 μm, 2.682 mrad, 2.587 for the vertical and horizontal directions, respectively. These measurements are compared to a traditional scan method and the results of the beam waist are found to be within error tolerance of the demonstrated instrument.

Electron beam pumped KrF lasers for fusion energy

International Nuclear Information System (INIS)

Sethian, J.D.; Friedman, M.; Giuliani, J.L. Jr.; Lehmberg, R.H.; Obenschain, S.P.; Kepple, P.; Wolford, M.; Hegeler, F.; Swanekamp, S.B.; Weidenheimer, D.; Welch, D.; Rose, D.V.; Searles, S.

2003-01-01

In this paper, we describe the development of electron beam pumped KrF lasers for inertial fusion energy. KrF lasers are an attractive driver for fusion, on account of their demonstrated very high beam quality, which is essential for reducing imprint in direct drive targets; their short wavelength (248 nm), which mitigates the growth of plasma instabilities; and their modular architecture, which reduces development costs. In this paper we present a basic overview of KrF laser technology as well as current research and development in three key areas: electron beam stability and transport; KrF kinetics and laser propagation; and pulsed power. The work will be cast in context of the two KrF lasers at the Naval Research Laboratory, The Nike Laser (5 kJ, single shot), and The Electra Laser (400-700 J repetitively pulsed)

Two transparent optical sensors for the positioning of detectors using a reference laser beam

Energy Technology Data Exchange (ETDEWEB)

Barriere, J.Ch.; Blumenfeld, H.; Bourdinaud, M.; Cloue, O.; Guyot, C.; Molinie, F.; Ponsot, P.; Saudemont, J.C.; Schuller, J.P.; Schune, Ph.; Sube, S. [CEA Saclay, 91 - Gif sur Yvette (France). Dept. d' Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l' Instrumentation Associee

1999-07-01

We have developed two different optical systems in order to position detectors with respect to a reference laser beam. The first system, a telescope, permits the absolute positioning of an element with respect to a reference laser beam. The resolution is of the order of 10 {mu}m in translation and 50 {mu}rad in rotation. It is highly transparent (-90%) permitting several elements to be aligned. A calibration procedure has also been studied and is currently being tested in order to obtain an absolute alignment information. The second system is a highly transparent (95%) two dimensional position sensor which allows the accurate positioning (below 20 {mu}m) of several (up to ten) elements to which each sensor is attached, transversally to a laser beam used as a reference straight line. The present useful area of the first sensor is 20 x 20 mm{sup 2} and is 15 x 15 mm{sup 2} for the second. In both case it can be further increased to meet the experiment's requirement. (authors)

Two transparent optical sensors for the positioning of detectors using a reference laser beam

International Nuclear Information System (INIS)

Barriere, J.Ch.; Blumenfeld, H.; Bourdinaud, M.; Cloue, O.; Guyot, C.; Molinie, F.; Ponsot, P.; Saudemont, J.C.; Schuller, J.P.; Schune, Ph.; Sube, S.

1999-01-01

We have developed two different optical systems in order to position detectors with respect to a reference laser beam. The first system, a telescope, permits the absolute positioning of an element with respect to a reference laser beam. The resolution is of the order of 10 μm in translation and 50 μrad in rotation. It is highly transparent (-90%) permitting several elements to be aligned. A calibration procedure has also been studied and is currently being tested in order to obtain an absolute alignment information. The second system is a highly transparent (95%) two dimensional position sensor which allows the accurate positioning (below 20 μm) of several (up to ten) elements to which each sensor is attached, transversally to a laser beam used as a reference straight line. The present useful area of the first sensor is 20 x 20 mm 2 and is 15 x 15 mm 2 for the second. In both case it can be further increased to meet the experiment's requirement. (authors)

Simulation of a low energy beam transport line

International Nuclear Information System (INIS)

Yang Yao; Liu Zhanwen; Zhang Wenhui; Ma Hongyi; Zhang Xuezhen; Zhao Hongwei; Yao Ze'en

2012-01-01

A 2.45 GHz electron cyclotron resonance intense proton source and a low energy beam transport line with dual-Glaser lens were designed and fabricated by Institute of Modern Physics for a compact pulsed hadron source at Tsinghua. The intense proton beams extracted from the ion source are transported through the transport line to match the downstream radio frequency quadrupole accelerator. Particle-in-cell code BEAMPATH was used to carry out the beam transport simulations and optimize the magnetic field structures of the transport line. Emittance growth due to space charge and spherical aberrations of the Glaser lens were studied in both theory and simulation. The results show that narrow beam has smaller aberrations and better beam quality through the transport line. To better match the radio frequency quadrupole accelerator, a shorter transport line is desired with sufficient space charge neutralization. (authors)

Laser induced focusing for over-dense plasma beams

International Nuclear Information System (INIS)

Schmidt, Peter; Boine-Frankenheim, Oliver; Mulser, Peter

2015-01-01

The capability of ion acceleration with high power, pulsed lasers has become an active field of research in the past years. In this context, the radiation pressure acceleration (RPA) mechanism has been the topic of numerous theoretical and experimental publications. Within that mechanism, a high power, pulsed laser beam hits a thin film target. In contrast to the target normal sheath acceleration, the entire film target is accelerated as a bulk by the radiation pressure of the laser. Simulations predict heavy ion beams with kinetic energy up to GeV, as well as solid body densities. However, there are several effects which limit the efficiency of the RPA: On the one hand, the Rayleigh-Taylor-instability limits the predicted density. On the other hand, conventional accelerator elements, such as magnetic focusing devices are too bulky to be installed right after the target. Therefore, we present a new beam transport method, suitable for RPA-like/over-dense plasma beams: laser induced focusing

Laser-driven particle and photon beams and some applications

International Nuclear Information System (INIS)

Ledingham, K W D; Galster, W

2010-01-01

Outstanding progress has been made in high-power laser technology in the last 10 years with laser powers reaching petawatt (PW) values. At present, there are 15 PW lasers built or being built around the world and plans are afoot for new, even higher power, lasers reaching values of exawatt (EW) or even zetawatt (ZW) powers. Petawatt lasers generate electric fields of 10 12 V m -1 with a large fraction of the total pulse energy being converted to relativistic electrons with energies reaching in excess of 1 GeV. In turn these electrons result in the generation of beams of protons, heavy ions, neutrons and high-energy photons. These laser-driven particle beams have encouraged many to think of carrying out experiments normally associated with conventional nuclear accelerators and reactors. To this end a number of introductory articles have been written under a trial name 'Laser Nuclear Physics' (Ledingham and Norreys 1999 Contemp. Phys. 40 367, Ledingham et al 2002 Europhys. News. 33 120, Ledingham et al 2003 Science 300 1107, Takabe et al 2001 J. Plasma Fusion Res. 77 1094). However, even greater strides have been made in the last 3 or 4 years in laser technology and it is timely to reassess the potential of laser-driven particle and photon beams. It must be acknowledged right from the outset that to date laser-driven particle beams have yet to compete favourably with conventional nuclear accelerator-generated beams in any way and so this is not a paper comparing laser and conventional accelerators. However, occasionally throughout the paper as a reality check, it will be mentioned what conventional nuclear accelerators can do.

Laser-driven particle and photon beams and some applications

Energy Technology Data Exchange (ETDEWEB)

Ledingham, K W D; Galster, W, E-mail: K.Ledingham@phys.strath.ac.u [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

2010-04-15

Outstanding progress has been made in high-power laser technology in the last 10 years with laser powers reaching petawatt (PW) values. At present, there are 15 PW lasers built or being built around the world and plans are afoot for new, even higher power, lasers reaching values of exawatt (EW) or even zetawatt (ZW) powers. Petawatt lasers generate electric fields of 10{sup 12} V m{sup -1} with a large fraction of the total pulse energy being converted to relativistic electrons with energies reaching in excess of 1 GeV. In turn these electrons result in the generation of beams of protons, heavy ions, neutrons and high-energy photons. These laser-driven particle beams have encouraged many to think of carrying out experiments normally associated with conventional nuclear accelerators and reactors. To this end a number of introductory articles have been written under a trial name 'Laser Nuclear Physics' (Ledingham and Norreys 1999 Contemp. Phys. 40 367, Ledingham et al 2002 Europhys. News. 33 120, Ledingham et al 2003 Science 300 1107, Takabe et al 2001 J. Plasma Fusion Res. 77 1094). However, even greater strides have been made in the last 3 or 4 years in laser technology and it is timely to reassess the potential of laser-driven particle and photon beams. It must be acknowledged right from the outset that to date laser-driven particle beams have yet to compete favourably with conventional nuclear accelerator-generated beams in any way and so this is not a paper comparing laser and conventional accelerators. However, occasionally throughout the paper as a reality check, it will be mentioned what conventional nuclear accelerators can do.

Diode line scanner for beam diagnostics

International Nuclear Information System (INIS)

Gustov, S.A.

1987-01-01

The device-scanning diode line is described. It is applied for beam profile measuring with space precision better than ± 0.5 mm and with discreteness of 3 mm along Y-axis and 0.25 mm along X-axis. The device is easy in construction, reliable and has a small time of information acquisition (2-5 min). The working range is from 100 to 10 6 rad/min (10 6 -10 10 part/mm 2 /s for 660 MeV protons). Radioresistance is 10 7 rad. The device can be applied for precise beam line element tuning at beam transporting and emittance measuring. The fixed diode line (a simplified device version) has smaller dimensions and smaller time of data acquisition (2-5 s). It is applied for quick preliminary beamline tuning. The flowsheet and different variants of data representation on beam profile are given

Preparation of a monoenergetic sodium beam by laser cooling and deflection

International Nuclear Information System (INIS)

Nellessen, J.; Sengstock, K.; Muller, J.H.; Ertmer, W.; Wallis, H.

1989-01-01

This paper reports on a sodium atomic beam with a density of approx. 10 5 at cm 3 within a velocity interval of less than 3 m/s with a mean velocity of typically 50-160 m/s which has been produced by laser deflection of a laser cooled atomic beam. Laser cooling with the frequency chirp method decelerates and cools a considerable part of an atomic beam into a narrow velocity group with a temperature of approx 30 mK as a part of the resulting atomic beam. This velocity group has been selectively deflected up to 30 degrees - 40 degrees using a light field with k vectors always perpendicular to the atomic trajectory. If the light field is prepared by use of a cylindrical lens, the angle of deflection is nearly independent from the actual orbit radius. For a laser frequency detuning of about one natural linewidth to the red, the strong frequency dependence of the light pressure force leads to a beam collimation via detuning-locking of the atomic trajectory. To avoid optical pumping we used a frequency modulated laser beam with a sideband spacing matched to the hyperfine splitting of the ground state. As the cooling was performed by the frequency chirp method, one can use a part of the cooling laser beam as deflecting laser beam. Typical velocity distributions in the deflected and undeflected atomic beam, measured 22 cm downstream the deflection zone. It shows the perfect transfer of the cooled velocity group from the laser cooled beam into the deflected beam; curve c) shows as comparison the result for the deflection of the initial thermal atomic beam

CONTINOUS EXTRACTED BEAM IN THE AGS FAST EXTERNAL BEAM LINE

International Nuclear Information System (INIS)

GLENN, J.W.; TSOUPAS, N.; BROWN, K.A.; BIRYUKOV, V.M.

2001-01-01

A method to split off a few percent of the 6 x 10 13 AGS beam delivered to the Slow External Beam (SEB) lines and send it down the Fast External Beam line (FEB) has been developed. The mission is to feed a counter experiment off the FEB that directly measures the neutrino mass using the muon storage ring. The use of normal thin septum splitters would have an excessive loss overhead and been optically difficult. The AGS Slow Extraction uses a third integer resonance with sextuple strength so the resonance width is a few percent of the beam width. This results in a low density tail which will be clipped by a bent crystal and deflected into the FEB channel. This clipping off of the tail should reduce losses in the SEB transport line. Details of modeled orbits, particle distribution and extraction trajectories into and out off the crystal will be given

Numerical analysis of the effects of non-conventional laser beam geometries during laser melting of metallic materials

International Nuclear Information System (INIS)

Safdar, Shakeel; Li, Lin; Sheikh, M A

2007-01-01

Laser melting is an important industrial activity encountered in a variety of laser manufacturing processes, e.g. selective laser melting, welding, brazing, soldering, glazing, surface alloying, cladding etc. The majority of these processes are carried out by using either circular or rectangular beams. At present, the melt pool characteristics such as melt pool geometry, thermal gradients and cooling rate are controlled by the variation of laser power, spot size or scanning speed. However, the variations in these parameters are often limited by other processing conditions. Although different laser beam modes and intensity distributions have been studied to improve the process, no other laser beam geometries have been investigated. The effect of laser beam geometry on the laser melting process has received very little attention. This paper presents an investigation of the effects of different beam geometries including circular, rectangular and diamond shapes on laser melting of metallic materials. The finite volume method has been used to simulate the transient effects of a moving beam for laser melting of mild steel (EN-43A) taking into account Marangoni and buoyancy convection. The temperature distribution, melt pool geometry, fluid flow velocities and heating/cooling rates have been calculated. Some of the results have been compared with the experimental data

Laser beam characterization with digital holograms

CSIR Research Space (South Africa)

Forbes, A

2013-04-01

Full Text Available We show how laser beam characterization may be done in real-time with digital holograms. We illustrate the power of the techniques by applying them to a variety of laser sources, from fibers to solid-state....

Standardization of beam line representations

International Nuclear Information System (INIS)

Carey, David C.

1998-01-01

Standardization of beam line representations means that a single set of data can be used in many situations to represent a beam line. This set of data should be the same no matter what the program to be run or the calculation to be made. We have concerned ourselves with three types of standardization: (1) The same set of data should be usable by different programs. (2) The inclusion of other items in the data, such as calculations to be done, units to be used, or preliminary specifications, should be in a notation similar to the lattice specification. (3) A single set of data should be used to represent a given beam line, no matter what is being modified or calculated. The specifics of what is to be modified or calculated can be edited into the data as part of the calculation. These three requirements all have aspects not previously discussed in a public forum. Implementations into TRANSPORT will be discussed

Standardization of beam line representations

International Nuclear Information System (INIS)

Carey, David C.

1999-01-01

Standardization of beam line representations means that a single set of data can be used in many situations to represent a beam line. This set of data should be the same no matter what the program to be run or the calculation to be made. We have concerned ourselves with three types of standardization: (1) The same set of data should be usable by different programs. (2) The inclusion of other items in the data, such as calculations to be done, units to be used, or preliminary specifications, should be in a notation similar to the lattice specification. (3) A single set of data should be used to represent a given beam line, no matter what is being modified or calculated. The specifics of what is to be modified or calculated can be edited into the data as part of the calculation. These three requirements all have aspects not previously discussed in a public forum. Implementations into TRANSPORT will be discussed

Propagation of Gaussian laser beam in cold plasma of Drude model

International Nuclear Information System (INIS)

Wang Ying; Yuan Chengxun; Zhou Zhongxiang; Li Lei; Du Yanwei

2011-01-01

The propagation characters of Gaussian laser beam in plasmas of Drude model have been investigated by complex eikonal function assumption. The dielectric constant of Drude model is representative and applicable in describing the cold unmagnetized plasmas. The dynamics of ponderomotive nonlinearity, spatial diffraction, and collision attenuation is considered. The derived coupling equations determine the variations of laser beam and irradiation attenuation. The modified laser beam-width parameter F, the dimensionless axis irradiation intensity I, and the spatial electron density distribution n/n 0 have been studied in connection with collision frequency, initial laser intensity and beam-width, and electron temperature of plasma. The variations of laser beam and plasma density due to different selections of parameters are reasonably explained, and results indicate the feasible modification of the propagating characters of laser beam in plasmas, which possesses significance to fast ignition, extended propagation, and other applications.

Apparatus and method for increasing the bandwidth of a laser beam

Science.gov (United States)

Wilcox, Russell B.

1992-01-01

A method and apparatus using sinusoidal cross-phase modulation, provides a laser pulse having a very broad bandwidth while substantially retaining the input laser's temporal shape. The modulator may be used in a master oscillator system for a laser having a master oscillator-power amplifier (MOPA) configration. The modulator utilizes a first laser providing an output wavelength .lambda. and a second laser providing an output wavelength shifted by a small amount to .lambda.+.DELTA..lambda.. Each beam has a single, linear polarization. Each beam is coupled into a length of polarization-preserving optical fiber. The first laser beam is coupled into the optical fiber with the beam's polarization aligned with the fiber's main axis, and the second beam is coupled into the fiber with its polarization rotated from the main axis by a predetermined angle. Within the fiber, the main axis' polarization defines an interference beam and the orthogonal axis' polarization defines a signal beam. In the interference beam, the first laser beam and the parallel polarized vector component of the other beam interfere to create areas of high and low intensity, which modulates the signal beam by cross phase modulation. Upon exit from the optical fiber, the beams are coupled out and the modulated signal beam is separated out by a polarization selector. The signal beam can be applied to coherence reducing systems to provide an output that is temporally and spatially incoherent. The U.S. Government has rights in this invention pursuant to Contract No. W7405-ENG-48 between the U.S. Department of Energy and the University of California for the operation of Lawrence Livermore National Laboratory.

Analytic model of bunched beams for harmonic generation in the low-gain free electron laser regime

Directory of Open Access Journals (Sweden)

G. Penn

2006-06-01

Full Text Available One scheme for harmonic generation employs free electron lasers (FELs with two undulators: the first uses a seed laser to modulate the energy of the electron beam; following a dispersive element which acts to bunch the beam, the second undulator radiates at a higher harmonic. These processes are currently evaluated using extensive calculations or simulation codes which can be slow to evaluate and difficult to set up. We describe a simple algorithm to predict the output of a harmonic generation beam line in the low-gain FEL regime, based on trial functions for the output radiation. Full three-dimensional effects are included. This method has been implemented as a Mathematica® package, named CAMPANILE, which runs rapidly and can be generalized to include effects such as asymmetric beams and misalignments. This method is compared with simulation results using the FEL code GENESIS, both for single stages of harmonic generation and for the LUX project, a design concept for an ultrafast x-ray facility, where multiple stages upshift the input laser frequency by factors of up to 200.

Excitation of Accelerating Plasma Waves by Counter-propagating Laser Beams

International Nuclear Information System (INIS)

Gennady Shvets; Nathaniel J. Fisch; Alexander Pukhov

2001-01-01

Generation of accelerating plasma waves using two counter-propagating laser beams is considered. Colliding-beam accelerator requires two laser pulses: the long pump and the short timing beam. We emphasize the similarities and differences between the conventional laser wakefield accelerator and the colliding-beam accelerator (CBA). The highly nonlinear nature of the wake excitation is explained using both nonlinear optics and plasma physics concepts. Two regimes of CBA are considered: (i) the short-pulse regime, where the timing beam is shorter than the plasma period, and (ii) the parametric excitation regime, where the timing beam is longer than the plasma period. Possible future experiments are also outlined

Laser-accelerated proton beams as a new particle source

Energy Technology Data Exchange (ETDEWEB)

Nuernberg, Frank

2010-11-15

The framework of this thesis is the investigation of the generation of proton beams using high-intensity laser pulses. In this work, an experimental method to fully reconstruct laser-accelerated proton beam parameters, called radiochromic film imaging spectroscopy (RIS), was developed. Since the proton beam expansion is a plasma expansion with accompanying electrons, a low-energy electron spectrometer was developed, built and tested to study the electron distribution matching to the proton beam energy distribution. Two experiments were carried out at the VULCAN Petawatt laser with the aim of showing dynamic control and enhancement of proton acceleration using multiple or defocused laser pulses. Irradiating the target with a long pulse, low-intensity laser (10{sup 12} W/cm{sup 2}) prior to the main pulse ({proportional_to}ns), an optimum pre-plasma density scale length of 60 {mu}m is generated leading to an enhancement of the maximum proton energy ({proportional_to}25%), the proton flux (factor of 3) and the beam uniformity. Proton beams were generated more efficiently than previously by driving thinner target foils at a lower intensity over a large area. The optimum condition was a 2 {mu}m foil irradiated with an intensity of 10{sup 19} W/cm{sup 2} onto a 60 {mu}m spot. Laser to proton beam efficiencies of 7.8% have been achieved (2.2% before) - one of the highest conversion efficiencies ever achieved. In the frame of this work, two separate experiments at the TRIDENT laser system have shown that these laser-accelerated proton beams, with their high number of particles in a short pulse duration, are well-suited for creating isochorically heated matter in extreme conditions. Besides the manipulation of the proton beam parameters directly during the generation, the primary aim of this thesis was the capture, control and transport of laser-accelerated proton beams by a solenoidal magnetic field lense for further purpose. In a joint project proposal, the laser and

Laser-accelerated proton beams as a new particle source

International Nuclear Information System (INIS)

Nuernberg, Frank

2010-01-01

The framework of this thesis is the investigation of the generation of proton beams using high-intensity laser pulses. In this work, an experimental method to fully reconstruct laser-accelerated proton beam parameters, called radiochromic film imaging spectroscopy (RIS), was developed. Since the proton beam expansion is a plasma expansion with accompanying electrons, a low-energy electron spectrometer was developed, built and tested to study the electron distribution matching to the proton beam energy distribution. Two experiments were carried out at the VULCAN Petawatt laser with the aim of showing dynamic control and enhancement of proton acceleration using multiple or defocused laser pulses. Irradiating the target with a long pulse, low-intensity laser (10 12 W/cm 2 ) prior to the main pulse (∝ns), an optimum pre-plasma density scale length of 60 μm is generated leading to an enhancement of the maximum proton energy (∝25%), the proton flux (factor of 3) and the beam uniformity. Proton beams were generated more efficiently than previously by driving thinner target foils at a lower intensity over a large area. The optimum condition was a 2 μm foil irradiated with an intensity of 10 19 W/cm 2 onto a 60 μm spot. Laser to proton beam efficiencies of 7.8% have been achieved (2.2% before) - one of the highest conversion efficiencies ever achieved. In the frame of this work, two separate experiments at the TRIDENT laser system have shown that these laser-accelerated proton beams, with their high number of particles in a short pulse duration, are well-suited for creating isochorically heated matter in extreme conditions. Besides the manipulation of the proton beam parameters directly during the generation, the primary aim of this thesis was the capture, control and transport of laser-accelerated proton beams by a solenoidal magnetic field lense for further purpose. In a joint project proposal, the laser and plasma physics group of the Technische Universitat

Spectral beam combining of diode lasers with high efficiency

DEFF Research Database (Denmark)

Müller, André; Vijayakumar, Deepak; Jensen, Ole Bjarlin

2012-01-01

Based on spectral beam combining we obtain 16 W of output power, combining two 1063 nm DBR-tapered diode lasers. The spectral separation within the combined beam can be used for subsequent sum-frequency generation.......Based on spectral beam combining we obtain 16 W of output power, combining two 1063 nm DBR-tapered diode lasers. The spectral separation within the combined beam can be used for subsequent sum-frequency generation....

Generation of monoenergetic ion beams with a laser accelerator

International Nuclear Information System (INIS)

Pfotenhauer, Sebastian M.

2009-01-01

A method for the generation of monoenergetic proton and ion beams from a laser-based particle accelerator is presented. This method utilizes the unique space-charge effects occurring during relativistic laser-plasma interactions on solid targets in combination with a dot-like particle source. Due to this unique interaction geometry, MeV proton beams with an intrinsically narrow energy spectrum were obtained, for the first time, from a micrometer-scale laser accelerator. Over the past three years, the acceleration scheme has been consistently improved to enhance both the maximum particle energy and the reliability of the setup. The achieved degree of reliability allowed to derive the first scaling laws specifically for monoenergetic proton beams. Furthermore, the acceleration scheme was expanded on other target materials, enabling the generation of monoenergetic carbon beams. The experimental work was strongly supported by the parallel development of a complex theoretical model, which fully accounts for the observations and is in excellent agreement with numerical simulations. The presented results have an extraordinarily broad scope way beyond the current thesis: The availability of monoenergetic ion beams from a compact laser-plasma beam source - in conjunction with the unique properties of laser-produced particle beams - addresses a number of outstanding applications in fundamental research, material science and medical physics, and will help to shape a new generation of accelerators. (orig.)

Generation of monoenergetic ion beams with a laser accelerator

Energy Technology Data Exchange (ETDEWEB)

Pfotenhauer, Sebastian M.

2009-01-29

A method for the generation of monoenergetic proton and ion beams from a laser-based particle accelerator is presented. This method utilizes the unique space-charge effects occurring during relativistic laser-plasma interactions on solid targets in combination with a dot-like particle source. Due to this unique interaction geometry, MeV proton beams with an intrinsically narrow energy spectrum were obtained, for the first time, from a micrometer-scale laser accelerator. Over the past three years, the acceleration scheme has been consistently improved to enhance both the maximum particle energy and the reliability of the setup. The achieved degree of reliability allowed to derive the first scaling laws specifically for monoenergetic proton beams. Furthermore, the acceleration scheme was expanded on other target materials, enabling the generation of monoenergetic carbon beams. The experimental work was strongly supported by the parallel development of a complex theoretical model, which fully accounts for the observations and is in excellent agreement with numerical simulations. The presented results have an extraordinarily broad scope way beyond the current thesis: The availability of monoenergetic ion beams from a compact laser-plasma beam source - in conjunction with the unique properties of laser-produced particle beams - addresses a number of outstanding applications in fundamental research, material science and medical physics, and will help to shape a new generation of accelerators. (orig.)

Conception and realisation of a system for the automatic alignment of a CO2 laser beam

International Nuclear Information System (INIS)

Mardon, Nathalie

1983-01-01

The present paper deals with the continuous control of the direction of a CO 2 laser beam, with a view to laser machining. Slow deviations, due to the cavity instability, move away the beam from the focusing system axis. An automatic alignment device acting on the last flat mirror of the optical line has been designed. This mirror is actuated by 2 motors which vary its inclination in 2 directions x,y. The first part of the present paper deals with the alignment principle worked according to the specific constraints to be faced and to the characteristics of the beam. It uses the revolution symmetry of the energy distribution of the beam: 4 thermocouples surrounding the beam on a same circumference yield equals signals if the beam is centered onto the 4 sensors. An angular displacement is characterised by the difference between the signals of 2 opposed detectors. The second part presents the digital feedback system: the divergence or the beam is computed from the differential signal by a coefficient K experimentally valued. The motor commands proceed from optical geometry laws. The filtering of the thermocouple signals is necessary in order to sort the slowly changing signal related to the beam displacement, from the higher frequency signal related to the laser system instability. The system has been implemented on a 16 bit microprocessor. (author) [fr

Generation of shape-invariant flat-top laser beams

CSIR Research Space (South Africa)

Ait-Ameur, K

2015-02-01

Full Text Available A great number of laser applications need in place of the usual Gaussian beam a flat-top intensity profile in the focal plane of a focusing lens. In general the transformation of the laser beam from the Gaussian to the flat-top shape is made by a...

A directly heated electron beam line source

International Nuclear Information System (INIS)

Iqbal, M.; Masood, K.; Rafiq, M.; Chaudhry, M.A.

2002-05-01

A 140-mm cathode length, Electron Beam Line Source with a high degree of focusing of the beam is constructed. The design principles and basic characteristic considerations for electron beam line source consists of parallel plate electrode geometric array as well as a beam power of 35kW are worked out. The dimensions of the beam at the work site are 1.25xl00mm. The gun is designed basically for the study of evaporation and deposition characteristic of refractory metals for laboratory use. However, it may be equally used for melting and casting of these metals. (author)

Numerical study of neutron beam divergence in a beam-fusion scenario employing laser driven ions

Science.gov (United States)

Alejo, A.; Green, A.; Ahmed, H.; Robinson, A. P. L.; Cerchez, M.; Clarke, R.; Doria, D.; Dorkings, S.; Fernandez, J.; McKenna, P.; Mirfayzi, S. R.; Naughton, K.; Neely, D.; Norreys, P.; Peth, C.; Powell, H.; Ruiz, J. A.; Swain, J.; Willi, O.; Borghesi, M.; Kar, S.

2016-09-01

The most established route to create a laser-based neutron source is by employing laser accelerated, low atomic-number ions in fusion reactions. In addition to the high reaction cross-sections at moderate energies of the projectile ions, the anisotropy in neutron emission is another important feature of beam-fusion reactions. Using a simple numerical model based on neutron generation in a pitcher-catcher scenario, anisotropy in neutron emission was studied for the deuterium-deuterium fusion reaction. Simulation results are consistent with the narrow-divergence (∼ 70 ° full width at half maximum) neutron beam recently served in an experiment employing multi-MeV deuteron beams of narrow divergence (up to 30° FWHM, depending on the ion energy) accelerated by a sub-petawatt laser pulse from thin deuterated plastic foils via the Target Normal Sheath Acceleration mechanism. By varying the input ion beam parameters, simulations show that a further improvement in the neutron beam directionality (i.e. reduction in the beam divergence) can be obtained by increasing the projectile ion beam temperature and cut-off energy, as expected from interactions employing higher power lasers at upcoming facilities.

Beam line for Schools: beyond expectations

CERN Multimedia

Cian O'Luanaigh

2014-01-01

Out of 292 proposals for CERN's first ever "Beam line for Schools" contest, two teams of high-school students – Odysseus' Comrades from Varvakios Pilot School in Athens, Greece and Dominicuscollege from Dominicus College in Nijmegen in the Netherlands – were selected to spend 10 days conducting their proposed experiments at the fully equipped T9 beam line on CERN's Meyrin site. Dedicated CERN staff and users from across the departments have put in a huge effort to ensure the success of the project.   Detector physicist Cenk Yidriz (centre, white helmet) explains the setup of the "Beamline for schools" experiment at the T9 beamline. It's finally beam time. After months of organisation, coding, engineering and even painting the experimental area, the T9 beam line is ready to deliver protons to experiments devised and built by high-school students. “They are here to collect data and experience the l...

Propagation Characteristics of High-Power Vortex Laguerre-Gaussian Laser Beams in Plasma

Directory of Open Access Journals (Sweden)

Zhili Lin

2018-04-01

Full Text Available The propagation characteristics of high-power laser beams in plasma is an important research topic and has many potential applications in fields such as laser machining, laser-driven accelerators and laser-driven inertial confined fusion. The dynamic evolution of high-power Laguerre-Gaussian (LG beams in plasma is numerically investigated by using the finite-difference time-domain (FDTD method based on the nonlinear Drude model, with both plasma frequency and collision frequency modulated by the light intensity of laser beam. The numerical algorithms and implementation techniques of FDTD method are presented for numerically simulating the nonlinear permittivity model of plasma and generating the LG beams with predefined parameters. The simulation results show that the plasma has different field modulation effects on the two exemplified LG beams with different cross-sectional patterns. The self-focusing and stochastic absorption phenomena of high-power laser beam in plasma are also demonstrated. This research also provides a new means for the field modulation of laser beams by plasma.

Selective injection locking of a multi-mode semiconductor laser to a multi-frequency reference beam

Science.gov (United States)

Pramod, Mysore Srinivas; Yang, Tao; Pandey, Kanhaiya; Giudici, Massimo; Wilkowski, David

2014-07-01

Injection locking is a well known and commonly used method for coherent light amplification. Usually injection locking is obtained on a single-mode laser injected by a single-frequency seeding beam. In this work we show that selective injection locking of a single-frequency may also be achieved on a multi-mode semiconductor laser injected by a multi-frequency seeding beam, if the slave laser provides sufficient frequency filtering. This selective injection locking condition depends critically on the frequency detuning between the free-running slave emission frequency and each injected frequency component. Stable selective injection locking to a set of three seeding components separated by 1.2 GHz is obtained. This system provides an amplification up to 37 dB of each component. This result suggests that, using distinct slave lasers for each frequency line, a set of mutually coherent high-power radiation modes can be tuned in the GHz frequency domain.

Development of BPM/BLM DAQ System for KOMAC Beam Line

Energy Technology Data Exchange (ETDEWEB)

Song, Young-Gi; Kim, Jae-Ha; Yun, Sang-Pil; Kim, Han-Sung; Kwon, Hyeok-Jung; Cho, Yong-Sub [Korea Atomic Energy Research Institute, Gyeongju (Korea, Republic of)

2016-10-15

The proton beam is accelerated from 3 MeV to 100 MeV through 11 DTL tanks. The KOMAC installed 10 beam lines, 5 for 20-MeV beams and 5 for 100-MeV beams. The proton beam is transmitted to two target room. The KOMAC has been operating two beam lines, one for 20 MeV and one for 100 MeV. New beam line, RI beam line is under commissioning. A Data Acquisition (DAQ) system is essential to monitor beam signals in an analog front-end circuitry from BPM and BLM at beam lines. A data acquisition (DAQ) system is essential to monitor beam signals in an analog front-end circuitry from BPM and BLM at beam lines. The DAQ digitizes beam signal and the sampling is synchronized with a reference signal which is an external trigger for beam operation. The digitized data is accessible by the Experimental Physics and Industrial Control System (EPICS)-based control system, which manages the whole accelerator control. The beam monitoring system integrates BLM and BPM signals into the control system and offers realtime data to operators. The IOC, which is implemented with Linux and a PCI driver, supports data acquisition as a very flexible solution.

Generalized emittance measurements in a beam transport line

International Nuclear Information System (INIS)

Skelly, J.; Gardner, C.; Luccio, A.; Kponou, A.; Reece, K.

1991-01-01

Motivated by the need to commission 3 beam transport lines for the new AGS Booster project, we have developed a generalized emittance-measurement program; beam line specifics are entirely resident in data tables, not in program code. For instrumentation, the program requires one or more multi-wire profile monitors; one or multiple profiles are acquired from each monitor, corresponding to one or multiple tunes of the transport line. Emittances and Twiss parameters are calculated using generalized algorithms. The required matix descriptions of the beam optics are constructed by an on-line general beam modeling program. Design of the program, its algorithms, and initial experience with it will be described. 4 refs., 2 figs., 1 tab

Excimer laser beam profile recording based on electrochemical etched polycarbonate

International Nuclear Information System (INIS)

Parvin, P.; Jaleh, B.; Zangeneh, H.R.; Zamanipour, Z.; Davoud-Abadi, Gh.R.

2008-01-01

There is no polymeric detector used to register the beam profile of UV lasers. Here, a method is proposed for the measurement of intensive UV beam pattern of the excimer lasers based on the photoablated polycarbonate detector after coherent UV exposure and the subsequent electrochemical etching. UV laser induced defects in the form of self-microstructuring on polycarbonate are developed to replicate the spatial intensity distribution as a beam profiler

Excimer laser beam profile recording based on electrochemical etched polycarbonate

Energy Technology Data Exchange (ETDEWEB)

Parvin, P. [Physics Department, Amirkabir University of Technology, P.O. Box 15875-4413, Hafez Ave, Tehran (Iran, Islamic Republic of); Laser Research Center, AEOI, P.O. Box 1165-8486, Tehran (Iran, Islamic Republic of)], E-mail: parvin@aut.ac.ir; Jaleh, B. [Physics Department, Bu-Ali Sina University, Postal Code 65174, Hamedan (Iran, Islamic Republic of); Zangeneh, H.R. [Physics Department, Amirkabir University of Technology, P.O. Box 15875-4413, Hafez Ave, Tehran (Iran, Islamic Republic of); Zamanipour, Z. [Laser Research Center, AEOI, P.O. Box 1165-8486, Tehran (Iran, Islamic Republic of); Davoud-Abadi, Gh.R. [Physics Department, Amirkabir University of Technology, P.O. Box 15875-4413, Hafez Ave, Tehran (Iran, Islamic Republic of)

2008-08-15

There is no polymeric detector used to register the beam profile of UV lasers. Here, a method is proposed for the measurement of intensive UV beam pattern of the excimer lasers based on the photoablated polycarbonate detector after coherent UV exposure and the subsequent electrochemical etching. UV laser induced defects in the form of self-microstructuring on polycarbonate are developed to replicate the spatial intensity distribution as a beam profiler.

Beam manipulation for compact laser wakefield accelerator based free-electron lasers

International Nuclear Information System (INIS)

Loulergue, A; Labat, M; Benabderrahmane, C; Couprie, M E; Evain, C; Malka, V

2015-01-01

Free-electron lasers (FELs) are a unique source of light, particularly in the x-ray domain. After the success of FELs based on conventional acceleration using radio-frequency cavities, an important challenge is the development of FELs based on electron bunching accelerated by a laser wakefield accelerator (LWFA). However, the present LWFA electron bunch properties do not permit use directly for a significant FEL amplification. It is known that longitudinal decompression of electron beams delivered by state-of-the-art LWFA eases the FEL process. We propose here a second order transverse beam manipulation turning the large inherent transverse chromatic emittances of LWFA beams into direct FEL gain advantage. Numerical simulations are presented showing that this beam manipulation can further enhance by orders of magnitude the peak power of the radiation. (paper)

750 keV beam line construction at the KEK

International Nuclear Information System (INIS)

Ishimaru, H.; Anami, S.; Inagaki, T.; Sakaue, T.; Itoh, K.; Fukumoto, S.

1976-01-01

The construction of 750 keV beam line of the KEK injector of the 12 GeV proton synchrotron was described. The beam line consists of the beam focusing quadrupoles, vacuum system, the electrostatic chopper and the various beam monitors. (author)

Principles of alignment of multi-beam lasers for thermonuclear purposes

International Nuclear Information System (INIS)

Basov, N.G.; Belyan, B.F.; Zhilkin, G.P.

1978-01-01

The problems of methods and equipment for power pulse laser adjustment, as well as the problem of adjustment automatization are considered. The adjustment of a power 12-channel ''Dolphin'' laser installation on the neodymium glass is taken as a concrete object. The adjustment objects are optical track of laser installation, guidance and laser radiation focusing system on the target, the system of target delivery to the focal volume, control system of element optical quality of laser installation and laser beams, as well as target radiation conditions in vacuum chamber. List of requirements of adjustment beams, possible sources of adjustment beams, equipment complex and laser installation adjustment methods are considered. The principles and scheme solutions of automatic adjustment of optical elements are discussed and the description of working samples of automatic joints is given. The problem of working laser beams imitation by adjusting and the possibilities of automatization of laser radiation space-angle characteristics control are considered. The control scheme of adjustment processes with computer as well as the switching on of adjustment automatic subsystem in the general automatization scheme of the ''Dolphin'' installation are discussed

Automated translating beam profiler for in situ laser beam spot-size and focal position measurements

Science.gov (United States)

Keaveney, James

2018-03-01

We present a simple and convenient, high-resolution solution for automated laser-beam profiling with axial translation. The device is based on a Raspberry Pi computer, Pi Noir CMOS camera, stepper motor, and commercial translation stage. We also provide software to run the device. The CMOS sensor is sensitive over a large wavelength range between 300 and 1100 nm and can be translated over 25 mm along the beam axis. The sensor head can be reversed without changing its axial position, allowing for a quantitative estimate of beam overlap with counter-propagating laser beams. Although not limited to this application, the intended use for this device is the automated measurement of the focal position and spot-size of a Gaussian laser beam. We present example data of one such measurement to illustrate device performance.

The IFUSP microtron accelerator beam transport line

International Nuclear Information System (INIS)

Rios, Paulo Beolchi

2002-01-01

In this work, the electron optical project of the IFUSP microtron beam transport line is presented, including the operational values for the parameters of the dipolar and quadrupolar electromagnets, as well as their location along the beam line. Analytical calculations and computer simulations were performed to obtain these results, and a programming tool was developed in order to analyze the beam parameters and to help studying racetrack microtrons. The electron optical simulations were split into two different study cases: the microtron booster, and the transfer line. In the first case, it was determined the main operational parameters of a microtron working far from its usual stability conditions. In the latter, it was done the basic design of the linking line between the booster and main (not yet built) microtrons, and between them and the experimental hall, with a total path length of approximately 32 m including large horizontal and vertical deflections with variable beam energy. (author)

Full-Duplex Digital Communication on a Single Laser Beam

Science.gov (United States)

Hazzard, D. A.; MacCannell, J. A.; Lee, G.; Selves, E. R.; Moore, D.; Payne, J. A.; Garrett, C. D.; Dahlstrom, N.; Shay, T. M.

2006-01-01

A proposed free-space optical communication system would operate in a full-duplex mode, using a single constant-power laser beam for transmission and reception of binary signals at both ends of the free-space optical path. The system was conceived for two-way data communication between a ground station and a spacecraft in a low orbit around the Earth. It has been estimated that in this application, a data rate of 10 kb/s could be achieved at a ground-station-to-spacecraft distance of 320 km, using a laser power of only 100 mW. The basic system concept is also applicable to terrestrial free-space optical communications. The system (see figure) would include a diode laser at one end of the link (originally, the ground station) and a liquid-crystal- based retroreflecting modulator at the other end of the link (originally, the spacecraft). At the laser end, the beam to be transmitted would be made to pass through a quarter-wave plate, which would convert its linear polarization to right circular polarization. For transmission of data from the laser end to the retroreflector end, the laser beam would be modulated with subcarrier phase-shift keying (SC-PSK). The transmitted beam would then pass through an aperture- sharing element (ASE) - basically, a mirror with a hole in it, used to separate the paths of the transmitted and received light beams. The transmitted beam would continue outward through a telescope (which, in the original application, would be equipped with a spacecraft-tracking system) that would launch the transmitted beam along the free-space optical path to the retroreflector end.

Applicability evaluation of eddy current testing for underwater laser beam welding

International Nuclear Information System (INIS)

Kobayashi, Noriyasu; Kasuya, Takashi; Ueno, Souichi; Ochiai, Makoto; Yuguchi, Yasuhiro

2010-01-01

We clarified a defect detecting capability of eddy current testing (ECT) as a surface inspection technique for underwater laser beam welding. An underwater laser beam welding procedure includes groove caving as a preparation, laser beam welding in groove and welding surface grinding as a post treatment. Therefore groove and grinded welding surface inspections are required underwater. We curried out defect detection tests using three kinds of specimens simulated a groove, reactor vessel nozzle dissimilar metal welding materials and a laser beam welding material with a cross coil ECT probe. From experimental results, we confirmed that it is possible to detect 0.3 mm or more depth electro-discharge machining slits on machining surfaces in all specimens and an ECT has possibility as a surface inspection technique for underwater laser beam welding. (author)

Dynamic control of laser driven proton beams by exploiting self-generated, ultrashort electromagnetic pulses

Energy Technology Data Exchange (ETDEWEB)

Kar, S., E-mail: s.kar@qub.ac.uk; Ahmed, H.; Nersisyan, G.; Hanton, F.; Naughton, K.; Lewis, C. L. S.; Borghesi, M. [Centre for Plasma Physics, School of Mathematics and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Brauckmann, S.; Giesecke, A. L.; Willi, O. [Institut für Laser-und Plasmaphysik, Heinrich-Heine-Universität, Düsseldorf (Germany)

2016-05-15

As part of the ultrafast charge dynamics initiated by high intensity laser irradiations of solid targets, high amplitude EM pulses propagate away from the interaction point and are transported along any stalks and wires attached to the target. The propagation of these high amplitude pulses along a thin wire connected to a laser irradiated target was diagnosed via the proton radiography technique, measuring a pulse duration of ∼20 ps and a pulse velocity close to the speed of light. The strong electric field associated with the EM pulse can be exploited for controlling dynamically the proton beams produced from a laser-driven source. Chromatic divergence control of broadband laser driven protons (upto 75% reduction in divergence of >5 MeV protons) was obtained by winding the supporting wire around the proton beam axis to create a helical coil structure. In addition to providing focussing and energy selection, the technique has the potential to post-accelerate the transiting protons by the longitudinal component of the curved electric field lines produced by the helical coil lens.

Output Beam Polarisation of X-ray Lasers with Transient Inversion

Science.gov (United States)

Janulewicz, K. A.; Kim, C. M.; Matouš, B.; Stiel, H.; Nishikino, M.; Hasegawa, N.; Kawachi, T.

It is commonly accepted that X-ray lasers, as the devices based on amplified spontaneous emission (ASE), did not show any specific polarization in the output beam. The theoretical analysis within the uniform (single-mode) approximation suggested that the output radiation should show some defined polarization feature, but randomly changing from shot-to-shot. This hypothesis has been verified by experiment using traditional double-pulse scheme of transient inversion. Membrane beam-splitter was used as a polarization selector. It was found that the output radiation has a significant component of p-polarisation in each shot. To explain the effect and place it in the line with available, but scarce data, propagation and kinetic effects in the non-uniform plasma have been analysed.

Propagation of coherently combined truncated laser beam arrays with beam distortions in non-Kolmogorov turbulence.

Science.gov (United States)

Tao, Rumao; Si, Lei; Ma, Yanxing; Zhou, Pu; Liu, Zejin

2012-08-10

The propagation properties of coherently combined truncated laser beam arrays with beam distortions through non-Kolmogorov turbulence are studied in detail both analytically and numerically. The analytical expressions for the average intensity and the beam width of coherently combined truncated laser beam arrays with beam distortions propagating through turbulence are derived based on the combination of statistical optics methods and the extended Huygens-Fresnel principle. The effect of beam distortions, such as amplitude modulation and phase fluctuation, is studied by numerical examples. The numerical results reveal that phase fluctuations have significant influence on the spreading of coherently combined truncated laser beam arrays in non-Kolmogorov turbulence, and the effects of the phase fluctuations can be negligible as long as the phase fluctuations are controlled under a certain level, i.e., a>0.05 for the situation considered in the paper. Furthermore, large phase fluctuations can convert the beam distribution rapidly to a Gaussian form, vary the spreading, weaken the optimum truncation effects, and suppress the dependence of spreading on the parameters of the non-Kolmogorov turbulence.

Time-of-flight laser spectrometer

International Nuclear Information System (INIS)

Izosimov, I.N.; Naumov, Yu.V.; Shishunov, N.A.

1982-01-01

A new method of laser spectroscopy with a multichannel way of recording is proposed. In the above method the beam of laser carrying out resonance excitation of studied atoms at the first stage, is directed along the atom beam. It the generation line width of this laser is much less than doppler broadening of spectral line caused by the atom velocities scattering in the beam, the selection of atoms according to velocities will take place, i. e. only atoms, having a definite projection of velocity on laser beam direction, will be excited. If laser line has several components, concealed in doppler circuit, the spectrum of velocities of excited atoms will also include several components. Spectrum of ion velocities obtained as a result of photoionization of excited atoms, reproduces within the limits of doppler circuit the structure of spectral line, corresponding to atom transition into the given excited state, as laser frequency at the dye is fixed in the process, of measurement. The method, proposed, is characterized not only by the property of multichannel but by a new way of atomic beam collimation. Analysis of ion velocities permits to carry out the regime of non-doppler spectroscopy at weakly collima-- ted atomic beams with collimation degree of 1:3. It gives a gain in sensitivity of about one order in comparison with one-channel methods while operating with high resolution (of 30 MHz order) [ru

Resonant ionization by laser beams: application to ions sources and to study the nuclear structure of radioactive tellurium isotopes

International Nuclear Information System (INIS)

Sifi, R.

2007-07-01

The radioactive ion beams that are produced through current isotope separators are well separated according to the A mass but not according to the Z parameter. The resonant ionization through laser beams applied to ion sources allows the production of radioactive ion beam in a very selective and efficient way by eliminating the isobaric contamination. The first chapter is dedicated to the resonant ionization by laser beams, we describe the principle, the experimental setting, the lasers used, the ionization schemes and the domain of application. The second chapter deals with the application of resonant ionization to laser ion sources for the production of radioactive ion beams. We present experimental tests performed for getting copper ion beams. Resonant ionization through laser is also used in the spectroscopy experiments performed at the Isolde (isotope separation on-line device) installation in CERN where more than 20 elements are ionized very efficiently. The technique is based on a frequency scanning around the excitation transition of the atoms in order to probe the hyperfine structure. Laser spectroscopy allows the determination of the hyperfine structure as well as the isotopic shift of atoms. In the third chapter the method is applied to the spectroscopy of tellurium atoms. First, we define the 2 parameters on which the extraction is based: charge radius and nuclear moments, then we present several theoretical models that we have used to assess our experimental results. (A.C.)

Laser optical pumping of sodium and lithium atom beams

International Nuclear Information System (INIS)

Cusma, J.T.

1983-01-01

The method of optical pumping with a continuous wave dye laser has been used to produce beams of polarized 23 Na atoms and polarized 6 Li atoms. Optical pumping of a 23 Na atom beam using either a multimode dye laser or a single frequency dye laser with a double passed acousto-optic modulator results in electron spin polarizations of 0.70-0.90 and nuclear spin polarizations of 0.75-0.90. Optical pumping of a 6 Li atom beam using a single frequency dye laser either with an acousto-optic modulator or with Doppler shift pumping results in electron spin polarizations of 0.77-0.95 and nuclear spin polarizations greater than 0.90. The polarization of the atom beam is measured using either the laser induced fluorescence in an intermediate magnetic field or a 6-pole magnet to determine the occupation probabilities of the ground hyperfine sublevels following optical pumping. The results of the laser optical pumping experiments agree with the results of a rate equation analysis of the optical pumping process which predicts that nearly all atoms are transferred into a single sublevel for our values of laser intensity and interaction time. The use of laser optical pumping in a polarized ion source for nuclear scattering experiments is discussed. The laser optical pumping method provides a means of constructing an intense source of polarized Li and Na ions

High quality proton beams from hybrid integrated laser-driven ion acceleration systems

Energy Technology Data Exchange (ETDEWEB)

Sinigardi, Stefano, E-mail: sinigardi@bo.infn.it [Dipartimento di Fisica e Astronomia, Università di Bologna and INFN Sezione di Bologna, Via Irnerio 46, I-40126 Bologna (Italy); Turchetti, Giorgio; Rossi, Francesco; Londrillo, Pasquale [Dipartimento di Fisica e Astronomia, Università di Bologna and INFN Sezione di Bologna, Via Irnerio 46, I-40126 Bologna (Italy); Giove, Dario; De Martinis, Carlo [Dipartimento di Fisica, Università di Milano and INFN Sezione di Milano, Via F.lli Cervi 201, I-20090 Segrate (Italy); Bolton, Paul R. [Kansai Photon Science Institute (JAEA), Umemidai 8-1-7, Kizugawa-shi, Kyoto 619-0215 (Japan)

2014-03-11

We consider a hybrid acceleration scheme for protons where the laser generated beam is selected in energy and angle and injected into a compact linac, which raises the energy from 30 to 60 MeV. The laser acceleration regime is TNSA and the energy spectrum is determined by the cutoff energy and proton temperature. The dependence of the spectrum on the target properties and the incidence angle is investigated with 2D PIC simulations. We base our work on widely available technologies and on laser with a short pulse, having in mind a facility whose cost is approximately 15M€. Using a recent experiment as the reference, we choose the laser pulse and target so that the energy spectrum obtained from the 3D PIC simulation is close to the one observed, whose cutoff energy was estimated to be over 50 MeV. Laser accelerated protons in the TNSA regime have wide energy spectrum and broad divergence. In this paper we compare three transport lines, designed to perform energy selection and beam collimation. They are based on a solenoid, a quadruplet of permanent magnetic quadrupoles and a chicane. To increase the maximum available energy, which is actually seen as an upper limit due to laser properties and available targets, we propose to inject protons into a small linac for post-acceleration. The number of selected and injected protons is the highest with the solenoid and lower by one and two orders of magnitude with the quadrupoles and the chicane respectively. Even though only the solenoid enables achieving to reach a final intensity at the threshold required for therapy with the highest beam quality, the other systems will be very likely used in the first experiments. Realistic start-to-end simulations, as the ones reported here, are relevant for the design of such experiments.

High quality proton beams from hybrid integrated laser-driven ion acceleration systems

Science.gov (United States)

Sinigardi, Stefano; Turchetti, Giorgio; Rossi, Francesco; Londrillo, Pasquale; Giove, Dario; De Martinis, Carlo; Bolton, Paul R.

2014-03-01

We consider a hybrid acceleration scheme for protons where the laser generated beam is selected in energy and angle and injected into a compact linac, which raises the energy from 30 to 60 MeV. The laser acceleration regime is TNSA and the energy spectrum is determined by the cutoff energy and proton temperature. The dependence of the spectrum on the target properties and the incidence angle is investigated with 2D PIC simulations. We base our work on widely available technologies and on laser with a short pulse, having in mind a facility whose cost is approximately 15 M €. Using a recent experiment as the reference, we choose the laser pulse and target so that the energy spectrum obtained from the 3D PIC simulation is close to the one observed, whose cutoff energy was estimated to be over 50 MeV. Laser accelerated protons in the TNSA regime have wide energy spectrum and broad divergence. In this paper we compare three transport lines, designed to perform energy selection and beam collimation. They are based on a solenoid, a quadruplet of permanent magnetic quadrupoles and a chicane. To increase the maximum available energy, which is actually seen as an upper limit due to laser properties and available targets, we propose to inject protons into a small linac for post-acceleration. The number of selected and injected protons is the highest with the solenoid and lower by one and two orders of magnitude with the quadrupoles and the chicane respectively. Even though only the solenoid enables achieving to reach a final intensity at the threshold required for therapy with the highest beam quality, the other systems will be very likely used in the first experiments. Realistic start-to-end simulations, as the ones reported here, are relevant for the design of such experiments.

High quality proton beams from hybrid integrated laser-driven ion acceleration systems

International Nuclear Information System (INIS)

Sinigardi, Stefano; Turchetti, Giorgio; Rossi, Francesco; Londrillo, Pasquale; Giove, Dario; De Martinis, Carlo; Bolton, Paul R.

2014-01-01

We consider a hybrid acceleration scheme for protons where the laser generated beam is selected in energy and angle and injected into a compact linac, which raises the energy from 30 to 60 MeV. The laser acceleration regime is TNSA and the energy spectrum is determined by the cutoff energy and proton temperature. The dependence of the spectrum on the target properties and the incidence angle is investigated with 2D PIC simulations. We base our work on widely available technologies and on laser with a short pulse, having in mind a facility whose cost is approximately 15M€. Using a recent experiment as the reference, we choose the laser pulse and target so that the energy spectrum obtained from the 3D PIC simulation is close to the one observed, whose cutoff energy was estimated to be over 50 MeV. Laser accelerated protons in the TNSA regime have wide energy spectrum and broad divergence. In this paper we compare three transport lines, designed to perform energy selection and beam collimation. They are based on a solenoid, a quadruplet of permanent magnetic quadrupoles and a chicane. To increase the maximum available energy, which is actually seen as an upper limit due to laser properties and available targets, we propose to inject protons into a small linac for post-acceleration. The number of selected and injected protons is the highest with the solenoid and lower by one and two orders of magnitude with the quadrupoles and the chicane respectively. Even though only the solenoid enables achieving to reach a final intensity at the threshold required for therapy with the highest beam quality, the other systems will be very likely used in the first experiments. Realistic start-to-end simulations, as the ones reported here, are relevant for the design of such experiments

Reverse spontaneous laser line sweeping in ytterbium fiber laser

Czech Academy of Sciences Publication Activity Database

Navrátil, Petr; Peterka, Pavel; Honzátko, Pavel; Kubeček, V.

2017-01-01

Roč. 14, č. 3 (2017), č. článku 035102. ISSN 1612-2011 R&D Projects: GA ČR(CZ) GA16-13306S Institutional support: RVO:67985882 ; RVO:68378271 Keywords : laser line sweeping * ytterbium * fiber lasers Subject RIV: BH - Optics, Masers, Lasers; BH - Optics, Masers, Lasers (FZU-D) OBOR OECD: Optics (including laser optics and quantum optics); Optics (including laser optics and quantum optics) (FZU-D) Impact factor: 2.537, year: 2016

The laser beam welding test of ODS fuel claddings

International Nuclear Information System (INIS)

Uwaba, Tomoyuki; Ukai, Shigeharu

2004-06-01

As a alternative method of pressurized resistance welding being currently developed, integrity evaluations for a laser beam welding joint between a ODS cladding tube and a FMS end plug were conducted for the purpose of studying the applicability of the laser beam welding technique to the welding with the lower end plug. The laser beam welding causes blowholes in the welding zone, whose effect on the high cycle fatigue strength of the joint is essential because of the flow-induced vibration during irradiation. The rotary bending tests using specimens with laser beam welding between ODS cladding tubes and FMS end plugs were carried out to evaluate the fatigue strength of the welding joint containing blowholes. The fatigue limit of stress amplitude about 200 MPa from 10 6 -10 7 cycles suggested that the laser beam welding joint had enough strength against the flow-induced vibration. Sizing of blowholes in the welding zone by using a micro X ray CT technique estimated the rate of defect areas due to blowholes at 1-2%. It is likely that the fatigue strength remained nearly unaffected by blowholes because of the no correlation between the breach of the rotary bending test specimen and the rate of defect area. Based on results of tensile test, internal burst test, Charpy impact test and fatigue test of welded zone, including study of allowable criteria of blowholes in the inspection, it is concluded that the laser beam welding can be probably applied to the welding between the ODS cladding tube and the FMS lower end plug. (author)

Turbulence-induced persistence in laser beam wandering.

Science.gov (United States)

Zunino, Luciano; Gulich, Damián; Funes, Gustavo; Pérez, Darío G

2015-07-01

We have experimentally confirmed the presence of long-memory correlations in the wandering of a thin Gaussian laser beam over a screen after propagating through a turbulent medium. A laboratory-controlled experiment was conducted in which coordinate fluctuations of the laser beam were recorded at a sufficiently high sampling rate for a wide range of turbulent conditions. Horizontal and vertical displacements of the laser beam centroid were subsequently analyzed by implementing detrended fluctuation analysis. This is a very well-known and widely used methodology to unveil memory effects from time series. Results obtained from this experimental analysis allow us to confirm that both coordinates behave as highly persistent signals for strong turbulent intensities. This finding is relevant for a better comprehension and modeling of the turbulence effects in free-space optical communication systems and other applications related to propagation of optical signals in the atmosphere.

Characteristics of a laser beam produced by using thermal lensing effect compensation in a fiber-coupled laser-diode-pumped Nd:YAG ceramic laser

International Nuclear Information System (INIS)

Kim, Duck-Lae; Kim, Byung-Tai

2010-01-01

The characteristics of a laser beam produced by using thermal lensing effect compensation in a fiber-coupled laser-diode Nd:YAG ceramic laser were investigated. The thermal lensing effect was compensated for by using a compensator, which was 25 mm away from the laser rod, with a focal length of 30 mm and an effective clear aperture of 22 mm. Using a compensator, the divergence and the beam propagation factor M 2 of the output beam were 5.5 mrad and 2.4, respectively, under a pump power of 12W. The high-frequency components in the compensated laser beam were removed.

Some aspects of VUV beam line design

International Nuclear Information System (INIS)

Gaupp, A.; Peatman, W.

1997-01-01

Some aspects of the design and usage of vacuum ultraviolet beam lines are discussed. Fermat's principle for imaging is introduced and applied to grating monochromators. Some typical vacuum ultraviolet beam lines are presented, and some further topics believed to be of importance today and in the future are mentioned. (author)

Atmospheric Error Correction of the Laser Beam Ranging

Directory of Open Access Journals (Sweden)

J. Saydi

2014-01-01

Full Text Available Atmospheric models based on surface measurements of pressure, temperature, and relative humidity have been used to increase the laser ranging accuracy by ray tracing. Atmospheric refraction can cause significant errors in laser ranging systems. Through the present research, the atmospheric effects on the laser beam were investigated by using the principles of laser ranging. Atmospheric correction was calculated for 0.532, 1.3, and 10.6 micron wavelengths through the weather conditions of Tehran, Isfahan, and Bushehr in Iran since March 2012 to March 2013. Through the present research the atmospheric correction was computed for meteorological data in base of monthly mean. Of course, the meteorological data were received from meteorological stations in Tehran, Isfahan, and Bushehr. Atmospheric correction was calculated for 11, 100, and 200 kilometers laser beam propagations under 30°, 60°, and 90° rising angles for each propagation. The results of the study showed that in the same months and beam emission angles, the atmospheric correction was most accurate for 10.6 micron wavelength. The laser ranging error was decreased by increasing the laser emission angle. The atmospheric correction with two Marini-Murray and Mendes-Pavlis models for 0.532 nm was compared.

Intra-cavity decomposition of a dual-directional laser beam

CSIR Research Space (South Africa)

Naidoo, Darryl

2011-01-01

Full Text Available A method of decomposing a dual-directional laser beam into a forward propagating field and a backward propagating field for an apertured plano-concave cavity is presented. An intra-cavity aperture is a simple method of laser beam shaping as higher...

High quality electron beams from a laser wakefield accelerator

Energy Technology Data Exchange (ETDEWEB)

Wiggins, S M; Issac, R C; Welsh, G H; Brunetti, E; Shanks, R P; Anania, M P; Cipiccia, S; Manahan, G G; Aniculaesei, C; Ersfeld, B; Islam, M R; Burgess, R T L; Vieux, G; Jaroszynski, D A [SUPA, Department of Physics, University of Strathclyde, Glasgow (United Kingdom); Gillespie, W A [SUPA, Division of Electronic Engineering and Physics, University of Dundee, Dundee (United Kingdom); MacLeod, A M [School of Computing and Creative Technologies, University of Abertay Dundee, Dundee (United Kingdom); Van der Geer, S B; De Loos, M J, E-mail: m.wiggins@phys.strath.ac.u [Pulsar Physics, Burghstraat 47, 5614 BC Eindhoven (Netherlands)

2010-12-15

High quality electron beams have been produced in a laser-plasma accelerator driven by femtosecond laser pulses with a peak power of 26 TW. Electrons are produced with an energy up to 150 MeV from the 2 mm gas jet accelerator and the measured rms relative energy spread is less than 1%. Shot-to-shot stability in the central energy is 3%. Pepper-pot measurements have shown that the normalized transverse emittance is {approx}1{pi} mm mrad while the beam charge is in the range 2-10 pC. The generation of high quality electron beams is understood from simulations accounting for beam loading of the wakefield accelerating structure. Experiments and self-consistent simulations indicate that the beam peak current is several kiloamperes. Efficient transportation of the beam through an undulator is simulated and progress is being made towards the realization of a compact, high peak brilliance free-electron laser operating in the vacuum ultraviolet and soft x-ray wavelength ranges.

Beam instrumentation for the BNL Heavy Ion Transfer Line

International Nuclear Information System (INIS)

Witkover, R.L.; Buxton, W.; Castillo, V.; Feigenbaum, I.; Lazos, A.; Li, Z.G.; Smith, G.; Stoehr, R.

1987-01-01

The Heavy Ion Transfer Line (HITL) was constructed to transport beams from the BNL Tandem Van de Graaff (TVDG) to be injected into the AGS. Because the beam line is approximately 2000 feet long and the particle rigidity is so low, 20 beam monitor boxes were placed along the line. The intensity ranges from 1 to 100 nanoAmps for the dc trace beam used for line set-up, to over 100 μA for the pulsed beam to be injected into the AGS. Profiles are measured using multiwire arrays (HARPS) while Faraday cups and beam transformers monitor the intensity. The electronics stations are operated through 3 Instrumentation Controllers networked to Apollo workstations in the TVDG and AGS control rooms. Details of the detectors and electronics designs and performance will be given

Faraday cup: absolute dosimetry for ELIMED beam line

International Nuclear Information System (INIS)

Leanza, R.; Romano, F.; Scuderi, V.; Amico, A.G.; Cuttone, G.; Larosa, G.; Milluzzo, G.; Petringa, G.; Pipek, J.; Cirrone, G.A.P.; Margarone, D.; Schillaci, F.

2017-01-01

The scientific community has shown a growing interest towards multidisciplinary applications of laser-driven beams. In this framework, the ELIMED (ELI-Beamlines MEDical and multidisciplinary applications) beamline will be the first transport beamline dedicated to the medical and multidisciplinary studies with laser-accelerated ion beams. Detectors for dosimetry represent one of key-element of the ELIMED beamline, allowing a dose delivering with good result as required in the clinical applications. In this contribution, a Faraday Cup for absolute dosimetry, designed and realized at INFN-LNS, is described.

Femtosecond laser-written double line waveguides in germanate and tellurite glasses

Science.gov (United States)

S. da Silva, Diego; Wetter, Niklaus U.; de Rossi, Wagner; Samad, Ricardo E.; Kassab, Luciana R. P.

2018-02-01

The authors report the fabrication and characterization of passive waveguides in GeO2-PbO and TeO2-ZnO glasses written with a femtosecond laser delivering pulses with 3μJ, 30μJ and 80fs at 4kHz repetition rate. Permanent refractive index change at the focus of the laser beam was obtained and waveguides were formed by two closely spaced laser written lines, where the light guiding occurs between them. The refractive index change at 632 nm is around 10-4 . The value of the propagation losses was around 2.0 dB/cm. The output mode profiles indicate multimodal guiding behavior. Raman measurements show structural modification of the glassy network. The results show that these materials are potential candidates for passive waveguides applications as low-loss optical components.

Characterisation of electron beams from laser-driven particle accelerators

Energy Technology Data Exchange (ETDEWEB)

Brunetti, E.; Manahan, G. G.; Shanks, R. P.; Islam, M. R.; Ersfeld, B.; Anania, M. P.; Cipiccia, S.; Issac, R. C.; Vieux, G.; Welsh, G. H.; Wiggins, S. M.; Jaroszynski, D. A. [Physics Department, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

2012-12-21

The development, understanding and application of laser-driven particle accelerators require accurate measurements of the beam properties, in particular emittance, energy spread and bunch length. Here we report measurements and simulations showing that laser wakefield accelerators can produce beams of quality comparable to conventional linear accelerators.

From laser cooling of non-relativistic to relativistic ion beams

International Nuclear Information System (INIS)

Schramm, U.; Bussmann, M.; Habs, D.

2004-01-01

Laser cooling of stored 24 Mg + ion beams recently led to the long anticipated experimental realization of Coulomb-ordered 'crystalline' ion beams in the low-energy RF-quadrupole storage ring PAul Laser CooLing Acceleration System (Munich). Moreover, systematic studies revealed severe constraints on the cooling scheme and the storage ring lattice for the attainment and maintenance of the crystalline state of the beam, which will be summarized. With the envisaged advent of high-energy heavy ion storage rings like SIS 300 at GSI (Darmstadt), which offer favourable lattice conditions for space-charge-dominated beams, we here discuss the general scaling of laser cooling of highly relativistic beams of highly charged ions and present a novel idea for direct three-dimensional beam cooling by forcing the ions onto a helical path

Real-time determination of laser beam quality by modal decomposition.

Science.gov (United States)

Schmidt, Oliver A; Schulze, Christian; Flamm, Daniel; Brüning, Robert; Kaiser, Thomas; Schröter, Siegmund; Duparré, Michael

2011-03-28

We present a real-time method to determine the beam propagation ratio M2 of laser beams. The all-optical measurement of modal amplitudes yields M2 parameters conform to the ISO standard method. The experimental technique is simple and fast, which allows to investigate laser beams under conditions inaccessible to other methods.

A beam position feedback system for beam lines at the photon factory

International Nuclear Information System (INIS)

Katsura, T.; Kamiya, Y.; Haga, K.; Mitsuhashi, T.

1987-01-01

The beam position of the synchrotron radiation produced from the Storage Ring was stabilized by a twofold position feedback system. A digital feedback system was developed to suppress the diurnal beam movement (one cycle of sin-like drifting motion per day) which became a serious problem in low-emittance operation. The feedback was applied to the closed-orbit-distortion (COD) correction system in order to cancel the position variation at all the beam lines proportionately to the variation monitored at one beam line. An analog feedback system is also used to suppress frequency components faster than the slow diurnal movement

BEAM LINE DESIGN FOR THE CERN HIRADMAT TEST FACILITY

CERN Document Server

Hessler, C; Goddard, B; Meddahi, M; Weterings, W

2009-01-01

The LHC phase II collimation project requires beam shock and impact tests of materials used for beam intercepting devices. Similar tests are also of great interest for other accelerator components such as beam entrance/exit windows and protection devices. For this purpose a dedicated High Radiation Material test facility (HiRadMat) is under study. This facility may be installed at CERN at the location of a former beam line. This paper describes the associated beam line which is foreseen to deliver a 450 GeV proton beam from the SPS with an intensity of up to 3×1013 protons per shot. Different beam line designs will be compared and the choice of the beam steering and diagnostic elements will be discussed, as well as operational issues.

Beam Line Design for the CERN Hiradmat Test Facility

CERN Document Server

Hessler, C; Goddard, B; Meddahi, M; Weterings, W

2010-01-01

The LHC phase II collimation project requires beam shock and impact tests of materials used for beam intercepting devices. Similar tests are also of great interest for other accelerator components such as beam entrance/exit windows and protection devices. For this purpose a dedicated High Radiation Material test facility (HiRadMat) is under study. This facility may be installed at CERN at the location of a former beam line. This paper describes the associated beam line which is foreseen to deliver a 450 GeV proton beam from the SPS with an intensity of up to 3×10**13 protons per shot. Different beam line designs will be compared and the choice of the beam steering and diagnostic elements will be discussed, as well as operational issues.

Generation and transport of laser accelerated ion beams

Energy Technology Data Exchange (ETDEWEB)

Schmidt, Peter; Boine-Frankenheim, Oliver [Technische Univ. Darmstadt (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Kornilov, Vladimir; Spaedtke, Peter [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Collaboration: LIGHT-Collaboration

2013-07-01

Currently the LIGHT- Project (Laser Ion Generation, Handling and Transport) is performed at the GSI Helmholtzzentrum fuer Schwerionenforschung GmbH Darmstadt. Within this project, intense proton beams are generated by laser acceleration, using the TNSA mechanism. After the laser acceleration the protons are transported through the beam pipe by a pulsed power solenoid. To study the transport a VORPAL 3D simulation is compared with CST simulation. A criterion as a function of beam parameters was worked out, to rate the importance of space charge. Furthermore, an exemplary comparison of the solenoid with a magnetic quadrupole-triplet was carried out. In the further course of the LIGHT-Project, it is planned to generate ion beams with higher kinetic energies, using ultra-thin targets. The acceleration processes that can appear are: RPA (Radiation Pressure Acceleration) and BOA (Break-Out Afterburner). Therefore the transport of an ion distribution will be studied, as it emerges from a RPA acceleration.

Traveling-wave laser-produced-plasma energy source for photoionization laser pumping and lasers incorporating said

Science.gov (United States)

Sher, Mark H.; Macklin, John J.; Harris, Stephen E.

1989-09-26

A traveling-wave, laser-produced-plasma, energy source used to obtain single-pass gain saturation of a photoionization pumped laser. A cylindrical lens is used to focus a pump laser beam to a long line on a target. Grooves are cut in the target to present a surface near normal to the incident beam and to reduce the area, and hence increase the intensity and efficiency, of plasma formation.

Statistical spatial properties of speckle patterns generated by multiple laser beams

International Nuclear Information System (INIS)

Le Cain, A.; Sajer, J. M.; Riazuelo, G.

2011-01-01

This paper investigates hot spot characteristics generated by the superposition of multiple laser beams. First, properties of speckle statistics are studied in the context of only one laser beam by computing the autocorrelation function. The case of multiple laser beams is then considered. In certain conditions, it is shown that speckles have an ellipsoidal shape. Analytical expressions of hot spot radii generated by multiple laser beams are derived and compared to numerical estimates made from the autocorrelation function. They are also compared to numerical simulations performed within the paraxial approximation. Excellent agreement is found for the speckle width as well as for the speckle length. Application to the speckle patterns generated in the Laser MegaJoule configuration in the zone where all the beams overlap is presented. Influence of polarization on the size of the speckles as well as on their abundance is studied.

Laser cooled ion beams and strongly coupled plasmas for precision experiments

International Nuclear Information System (INIS)

Bussmann, Michael

2008-01-01

This cumulative thesis summarizes experimental and theoretical results on cooling of ion beams using single-frequency, single-mode tabletop laser systems. It consists of two parts. One deals with experiments on laser-cooling of ion beams at relativistic energies, the other with simulations of stopping and sympathetic cooling of ions for precision in-trap experiments. In the first part, experimental results are presented on laser-cooling of relativistic C 3+ ion beams at a beam energy of 122 MeV/u, performed at the Experimental Storage Ring (ESR) at GSI. The main results presented in this thesis include the first attainment of longitudinally space-charge dominated relativistic ion beams using pure laser-cooling. The second part lists theoretical results on stopping and sympathetic cooling of ions in a laser-cooled one-component plasma of singly charged 24 Mg ions, which are confined in a three-dimensional harmonic trap potential. (orig.)

Line shape and ray trace calculations in saturated X-ray lasers: Application to Ni-like silver

International Nuclear Information System (INIS)

Benredjem, D.; Guilbaud, O.; Moeller, C.; Klisnick, A.; Ros, D.; Dubau, J.; Calisti, A.; Talin, B.

2006-01-01

Longitudinal coherence length in X-ray lasers depends strongly on the shape of the amplified line. We have modelled an experiment performed at the LULI facility of Ecole Polytechnique. The experiment was devoted to the study of the temporal (longitudinal) coherence of the transient Ni-like silver 4d-4p transition X-ray laser at 13.9 nm. Accurate line shape calculations using PPP, a spectral line shape code, confirm that the Voigt profile is a good approximation for this X-ray laser line. This allows us to extensively use the Voigt shape in conditions where the amplifier, i.e. the plasma produced by the interaction of a high intensity laser with a slab target, is neither stationary nor homogeneous. Our calculations involve a ray trace code which is a post-processor to the hydrodynamic simulation EHYBRID. As the effect of saturation is important for the level populations and gains we include the interaction between the amplified beam and the medium using the Maxwell-Bloch formalism. While the FWHM of the spontaneous emission profile is ∼10 mA, the amplified X-ray line exhibits gain narrowing leading to the smaller width ∼3 mA. Comparison with experiment is discussed

Transverse Laser Beam Shaping in High Brightness Electron Gun at ATF

CERN Document Server

Roychowdhury, S

2005-01-01

The brightness of electron beams from a photo injector is influenced by the transverse and longitudinal distribution of the laser beam illuminating the cathode. Previous studies at Brookhaven Accelerator Test Facility have shown that formation of an ideal e-beam with lowest transverse emittance requires uniform circular distribution of the emitted electrons. The use of the uniformly distributed power of the laser beam may not lead to that of the emitted electrons because of the non-uniform quantum efficiency. A proper shaping of the laser beam can compensate for this non-uniformity. In this paper we describe the use of digital light processing (DLP) technique based on digital mirror device (DMD) for spatial modulation of the laser beam, for measurements of the quantum efficiency map, and for creating the desirable e-beam density profiles. A DMD is aμelectronic mechanical system (MEMS) comprising of millions of highly reflectiveμmirrors controlled by underlying electronics. We present exper...

Electron beam cooling by laser

CERN Document Server

Urakawa, J; Terunuma, N; Taniguchi, T; Yamazaki, Y; Hirano, K; Nomura, M; Sakai, I; Takano, M; Sasao, N; Honda, Y; Noda, A; Bulyak, E; Gladkikh, P; Mystykov, A; Zelinsky, A; Zimmermann, Frank

2004-01-01

In 1997, Z.Huang and R.Ruth proposed a compact laser-electron storage ring (LESR) for electron beam cooling or x-ray generation. Because the laser-wire monitor in the ATF storage ring has worked well and demonstrated the achievement of the world's smallest transverse emittance for a circulating electron beam, we have started the design of a small storage ring with about 10 m circumference and the development of basic technologies for the LESR. In this paper, we describe the design and experimental results of pulse stacking in a 42-cm long optical cavity. Since our primary purpose is demonstrating the proof-of-principle of the LESR, we will then discuss the future experimental plan at the KEK-ATF for the generation of high average-brilliance gamma-rays.

An online, energy-resolving beam profile detector for laser-driven proton beams

Energy Technology Data Exchange (ETDEWEB)

Metzkes, J.; Rehwald, M.; Obst, L.; Schramm, U. [Helmholtz-Zentrum Dresden–Rossendorf (HZDR), Bautzner Landstr. 400, 01328 Dresden (Germany); Technische Universität Dresden, 01062 Dresden (Germany); Zeil, K.; Kraft, S. D.; Sobiella, M.; Schlenvoigt, H.-P. [Helmholtz-Zentrum Dresden–Rossendorf (HZDR), Bautzner Landstr. 400, 01328 Dresden (Germany); Karsch, L. [OncoRay-National Center for Radiation Research in Oncology, Technische Universität Dresden, 01307 Dresden (Germany)

2016-08-15

In this paper, a scintillator-based online beam profile detector for the characterization of laser-driven proton beams is presented. Using a pixelated matrix with varying absorber thicknesses, the proton beam is spatially resolved in two dimensions and simultaneously energy-resolved. A thin plastic scintillator placed behind the absorber and read out by a CCD camera is used as the active detector material. The spatial detector resolution reaches down to ∼4 mm and the detector can resolve proton beam profiles for up to 9 proton threshold energies. With these detector design parameters, the spatial characteristics of the proton distribution and its cut-off energy can be analyzed online and on-shot under vacuum conditions. The paper discusses the detector design, its characterization and calibration at a conventional proton source, as well as the first detector application at a laser-driven proton source.

Double-sided electron-beam generator for KrF laser excitation

International Nuclear Information System (INIS)

Schlitt, L.; Swingle, J.

1980-05-01

Several laser systems excited by electron beam have been identified as candidates for pump sources for laser fusion applications. The electron beam generators required must be compact, reliable and capable of synchronization with other system components. A KrF laser producing a minimum output of 25 J was needed for the RAPIER (Raman Amplifier Pumped by Intensified Excimer Radiation) system. A double-sided electron beam system was designed and constructed specifically for this purpose and has produced > 35 J of KrF output. Each of the two electron beam machines in the system operates with an rms jitter of 0.4 ns and together occupy approx. 3.5 m 2 of floor space. The successful operation of this laser has engendered requests for a description of the engineering details of this system. This document contains a brief description of the design issues and a full set of engineering drawings for this KrF laser amplifier

Metal impurity injection into DIVA plasmas with a Q-switched laser beam

International Nuclear Information System (INIS)

Yamauchi, Toshihiko; Nagami, Masayuki; Sengoku, Seio; Kumagai, Katsuaki

1978-08-01

Metal impurity injection into DIVA plasmas with a Q-switched ruby laser beam is described. Metal materials used are aluminium and gold. The Q-switched laser beam is incident onto a thin metal film thickness about 0.2 μm coated on pyrex glass plate surface. The metal film is vaporized by the laser beam and injected into DIVA plasma. The laser-beam injection method has advantages of sharp profile of vaporized metal, easy control of vaporized metal quantity and injection rate control of metal vapor. (author)

Longitudinal dynamics of laser-cooled fast ion beams

DEFF Research Database (Denmark)

Weidemüller, M.; Eike, B.; Eisenbarth, U.

1999-01-01

We present recent results of our experiments on laser cooling of fast stored ion beams at the Heidelberg Test Storage Ring. The longitudinal motion of the ions is directly cooled by the light pressure force, whereas efficient transverse cooling is obtained indirectly by longitudinal-transverse co......We present recent results of our experiments on laser cooling of fast stored ion beams at the Heidelberg Test Storage Ring. The longitudinal motion of the ions is directly cooled by the light pressure force, whereas efficient transverse cooling is obtained indirectly by longitudinal....... When applying laser cooling in square-well buckets over long time intervals, hard Coulomb collisions suddenly disappear and the longitudinal temperature drops by about a factor of three. The observed longitudinal behaviour of the beam shows strong resemblance with the transition to an Coulomb...

Lasers and particle beam for fusion and strategic defense

International Nuclear Information System (INIS)

Anon.

1986-01-01

This special issue of the Journal of Fusion Energy consists of the edited transscripts of a symposium on the applications of laser and particle beams to fusion and strategic defense. Its eleven papers discuss these topics: the Strategic Defense Initiative; accelerators for heavy ion fusion; rf accelerators for fusion and strategic defense; Pulsed power, ICF, and the Strategic Defense Initiative; chemical lasers; the feasibility of KrF lasers for fusion; the damage resistance of coated optic; liquid crystal devices for laser systems; fusion neutral-particle beam research and its contribution to the Star Wars program; and induction linacs and free electron laser amplifiers for ICF devices and directed-energy weapons

Propagation of an intense laser beam in a tapered plasma channel

International Nuclear Information System (INIS)

Jha, Pallavi; Singh, Ram Gopal; Upadhyaya, Ajay K.; Mishra, Rohit K.

2008-01-01

Propagation characteristics and modulation instability of an intense laser beam propagating in an axially tapered plasma channel, having a parabolic radial density profile, are studied. Using the source-dependent expansion technique, the evolution equation for the laser spot is set up and conditions for propagation of the laser beam with a constant spot size (matched beam) are obtained. Further, the dispersion relation and growth rate of modulation instability of the laser pulse as it propagates through linearly and quadratically tapered plasma channels, have been obtained

GeV electron beams from centimeter-scale channel guided laser wakefield

International Nuclear Information System (INIS)

Gonsalves, A.; Nakamura, K.; Panasenko, D.; Toth, Cs.; Esarey, E.; Schroeder; Hooker, S.M.; Leemans, W.P.; Hooker, S.M.

2007-01-01

Results are presented on the generation of quasi-monoenergetic electron beams with energy up to 1 GeV using a 40TW laser and a 3.3 cm-long hydrogen-filled capillary discharge waveguide. Electron beams were not observed without a plasma channel, indicating that self-focusing alone could not be relied upon for effective guiding of the laser pulse. Results are presented of the electron beam spectra, and the dependence of the reliability of producing electron beams as a function of laser and plasma parameters

Property Investigation of Laser Cladded, Laser Melted and Electron Beam Melted Ti-Al6-V4

Science.gov (United States)

2006-05-01

UNCLASSIFIED/UNLIMITED UNCLASSIFIED/UNLIMITED Figure 3: Examples of electron beam melted net shape parts; powder bed [3]. 1.4 Laser Cladding ...description, www.arcam.com. [4] K.-H. Hermann, S. Orban, S. Nowotny, Laser Cladding of Titanium Alloy Ti6242 to Restore Damaged Blades, Proceedings...Property Investigation of Laser Cladded , Laser Melted and Electron Beam Melted Ti-Al6-V4 Johannes Vlcek EADS Deutschland GmbH Corporate Research

A laser-based beam profile monitor for the SLC/SLD interaction region

International Nuclear Information System (INIS)

Alley, R.; Arnett, D.; Bong, E.; Colocho, W.; Frisch, J.; Horton-Smith, S.; Inman, W.; Jobe, K.; Kotseroglou, T.; McCormick, D.; Nelson, J.; Scheeff, M.; Wagner, S.; Ross, M.C.

1996-01-01

Beam size estimates made using beam-beam deflections are used for optimization of the Stanford linear collider (SLC) electron-positron beam sizes. Typical beam sizes and intensities expected for 1996 operations are 2.1 x 0.6 μm (x, y) at 4.0.10 10 particles per pulse. Conventional profile monitors, such as scanning wires, fail at charge densities well below this. The laser-based profile monitor uses a finely-focused 350-nm wavelength tripled YLF laser pulse that traverses the particle beam path about 29 cm away from the e + /e - IP. Compton scattered photons and degraded e + /e - are detected as the beam is steered across the laser pulse. The laser pulse has a transverse size of 380 nm and a Rayleigh range of about 5 μm. (orig.)

Laser beams hazards. Experimental determination of a laser ocular lesion threshold

International Nuclear Information System (INIS)

Courant, D.; Court, L.; Gueneau, G.; Bagot, J.D.; Abadie, B.; Brouillet, B.; Laborde, G.; Duchene, A.

1984-10-01

The risks due to the use of laser have called for the definition of exposure limits. The determination of these values requires the knowledge of the physical parameters of exposure and both the anatomical and the physiological properties of the skin and the eye. The parameters of the mechanisms involved in the biological effects of laser beams, the concept of damage criteria and the experimental results found in the literature are first discussed. The main parameter of the beam determining the injury: wavelength, time and the size of the image are then analysed. Some examples of experimental determinations of laser ocular lesion thresholds, carried out on the retinae of the rabbit and the monkey, emphasize, the difficulties met in the determination of the exposure limits. These experiments involve the effect of laser beam in the visible spectrum. Several techniques are compared: a direct ophthalmoscopic observation, a method with fluorescein angiography, a histologic study with light microscopy and an electrophysiological study. The results show that the determination of exposure limits is chiefly a function of the experimental techniques used, the delay of the observation after exposure and the probability of risk selected. The experimental results demonstrate the importance of these parameters and bring into light the uncertainties of the present guidelines [fr

Preliminary design of experiment high power density laser beam interaction with plasmas and development of a cold cathode electron beam laser amplifier

International Nuclear Information System (INIS)

Mosavi, R.K.; Kohanzadeh, Y.; Taherzadeh, M.; Vaziri, A.

1976-01-01

This experiment is designed to produce plasma by carbon dioxide pulsed laser, to measure plasma parameters and to study the interaction of the produced plasma with intense laser beams. The objectives of this experiment are the following: 1. To set up a TEA CO 2 laser oscillator and a cold cathode electron beam laser amplifier together as a system, to produce high energy optical pulses of short duration. 2. To achieve laser intensities of 10 11 watt/cm 2 or more at solid targets of polyethylene (C 2 H 4 )n, lithium hydride (LiH), and lithium deuteride in order to produce high temperature plasmas. 3. To design and develop diagnostic methods for studies of laser-induced plasmas. 4. To develop a high power CO 2 laser amplifier for the purpose of upgrading the optical energy delivered to the targets

Conceptual development of the Laser Beam Manifold (LBM)

Science.gov (United States)

Campbell, W.; Owen, R. B.

1979-01-01

The laser beam manifold, a device for transforming a single, narrow, collimated beam of light into several beams of desired intensity ratios is described. The device consists of a single optical substrate with a metallic coating on both optical surfaces. By changing the entry point, the number of outgoing beams can be varied.

Characterization of the Goubau line for testing beam diagnostic instruments

Science.gov (United States)

Kim, S. Y.; Stulle, F.; Sung, C. K.; Yoo, K. H.; Seok, J.; Moon, K. J.; Choi, C. U.; Chung, Y.; Kim, G.; Woo, H. J.; Kwon, J.; Lee, I. G.; Choi, E. M.; Chung, M.

2017-12-01

One of the main characteristics of the Goubau line is that it supports a low-loss, non-radiated surface wave guided by a dielectric-coated metal wire. The dominant mode of the surface wave along the Goubau line is a TM01 mode, which resembles the pattern of the electromagnetic fields induced in the metallic beam pipe when the charged particle beam passes through it. Therefore, the Goubau line can be used for the preliminary bench test and performance optimization of the beam diagnostic instruments without requiring charged particle beams from the accelerators. In this paper, we discuss the basic properties of the Goubau line for testing beam diagnostic instruments and present the initial test results for button-type beam position monitors (BPMs). The experimental results are consistent with the theoretical estimations, which indicates that Goubau line allows effective testing of beam diagnostic equipment.

PEP Laser Surveying System

International Nuclear Information System (INIS)

Lauritzen, T.; Sah, R.C.

1979-03-01

A Laser Surveying System has been developed to survey the beam elements of the PEP storage ring. This system provides automatic data acquisition and analysis in order to increase survey speed and to minimize operator error. Two special instruments, the Automatic Readout Micrometer and the Small Automatic Micrometer, have been built for measuring the locations of fiducial points on beam elements with respect to the light beam from a laser. These instruments automatically encode offset distances and read them into the memory of an on-line computer. Distances along the beam line are automatically encoded with a third instrument, the Automatic Readout Tape Unit. When measurements of several beam elements have been taken, the on-line computer analyzes the measured data, compared them with desired parameters, and calculates the required adjustments to beam element support stands

Advanced chemical oxygen iodine lasers for novel beam generation

Science.gov (United States)

Wu, Kenan; Zhao, Tianliang; Huai, Ying; Jin, Yuqi

2018-03-01

Chemical oxygen iodine laser, or COIL, is an impressive type of chemical laser that emits high power beam with good atmospheric transmissivity. Chemical oxygen iodine lasers with continuous-wave plane wave output are well-developed and are widely adopted in directed energy systems in the past several decades. Approaches of generating novel output beam based on chemical oxygen iodine lasers are explored in the current study. Since sophisticated physical processes including supersonic flowing of gaseous active media, chemical reacting of various species, optical power amplification, as well as thermal deformation and vibration of mirrors take place in the operation of COIL, a multi-disciplinary model is developed for tracing the interacting mechanisms and evaluating the performance of the proposed laser architectures. Pulsed output mode with repetition rate as high as hundreds of kHz, pulsed output mode with low repetition rate and high pulse energy, as well as novel beam with vector or vortex feature can be obtained. The results suggest potential approaches for expanding the applicability of chemical oxygen iodine lasers.

Muon Beam Studies in the H4 beam line and the Gamma Irradiation Facility (GIF++)

CERN Document Server

Margraf, Rachel; CERN. Geneva. EN Department

2017-01-01

In this report, I summarize my work of detailed study and optimization of the muon beam configuration of H4 beam line in SPS North Area. Using Monte-Carlo simulations, I studied the properties and behavior of the muon beam in combination with the field of the large, spectrometer “ GOLIATH” magnet at -1.5, -1.0, 0, 1.0 and 1.5 Tesla, which is shown to affect the central x position of the muon beam that is delivered to the Gamma Irradiation Facility (GIF++). I also studied the muon beam for different configurations of the two XTDV beam dumps upstream of GIF++ in the H4 beam line. I will also discuss my role in mapping the magnetic field of the GOLIATH magnet in the H4 beam line.

Laser cooled ion beams and strongly coupled plasmas for precision experiments

Energy Technology Data Exchange (ETDEWEB)

Bussmann, Michael

2008-03-17

This cumulative thesis summarizes experimental and theoretical results on cooling of ion beams using single-frequency, single-mode tabletop laser systems. It consists of two parts. One deals with experiments on laser-cooling of ion beams at relativistic energies, the other with simulations of stopping and sympathetic cooling of ions for precision in-trap experiments. In the first part, experimental results are presented on laser-cooling of relativistic C{sup 3+} ion beams at a beam energy of 122 MeV/u, performed at the Experimental Storage Ring (ESR) at GSI. The main results presented in this thesis include the first attainment of longitudinally space-charge dominated relativistic ion beams using pure laser-cooling. The second part lists theoretical results on stopping and sympathetic cooling of ions in a laser-cooled one-component plasma of singly charged {sup 24}Mg ions, which are confined in a three-dimensional harmonic trap potential. (orig.)

Laser welding of galvanized steel: analytical study in view of dual-beam solution

International Nuclear Information System (INIS)

Iqbal, S.; Gualini, M.M.S.

2005-01-01

In this paper, the solution of a new dual laser beam method to lap weld galvanized steel sheets is being discussed, modeled and analyzed. This method involves a pre-cursor beam and a higher-power actual beam used on the job in tandem, generated independently or otherwise split from the same source. The pre-cursor beam cuts a slot, thus making an exit path for the zinc vapours, while the second beam performs the needed welding. After giving detailed theoretical coverage and diverse mathematical simulations, the paper also presents and discusses some experimental results of the method. Along with this, a comparison is being made with some other methods proposed till today to solve this problem including some quantitative analysis. As presented, general view in industrial perspective supports this method to be easier to implement on the production lines along with yielding desired results. (author)

Dual-beam operation of the Astra Gemini laser facility

International Nuclear Information System (INIS)

Bryan Parry; Nicola Booth; Oleg Chekhlov; John Collier; Edwin Divall; Klaus Ertel; Peta Foster; Steve Hawkes; Chris Hooker; Victoria Marshall

2010-01-01

Complete text of publication follows. Gemini is a Petawatt class Ti:Sapphire laser system at the Rutherford Appleton Laboratory, UK. It was designed as a dual beam laser, with two independently configurable 800 nm beams delivering 15 J to target in 30 fs pulse duration, giving 0.5 PW peak power per beam. It is capable of reaching intensities over 10 22 W/cm 2 . Gemini can achieve a maximum repetition rate of one shot every 20 seconds, allowing it to deliver hundreds of shots per day; a feature which makes it unique among PW lasers. Already this has proved valuable in experiments involving electron acceleration in gas jets. The first Gemini beamline became operational in 2008. Commissioning of the second beam was deferred to allow earlier access to the facility by experimental scientists, and to develop operational experience. In this mode, Gemini has already produced significant results from a number of advanced plasma physics experiments. The second beam of Gemini is now coming online, with the first dual beam experiment starting in June 2010. The flexibility offered by two short pulse, ultra high intensity beams is another aspect that makes this laser system unique. The dual beams enable versatile configurations and illumination geometries, facilitating a wider range of experiments than is possible with only a single beam. Operationally however, it introduces additional factors which must be monitored and controlled in order to achieve experimental success. The beams must be timed with respect to each other with accuracy less than the pulse duration. The beam foci must also be overlapped spatially, and the stability of both these factors maintained over extended periods. We report on the second beam commissioning process, including the latest results on the characteristics, stability and spatio-temporal overlap of the two beams. We present details of amplifier performance, along with measurements of beam quality, focal spot, pulse duration and contrast, to give a

New wiggler beam line for SSRL

International Nuclear Information System (INIS)

Hoyer, E.

1982-08-01

A new high-intensity-beam line with a wiggler magnet source is described. This project, in final stages of design, is a joint effort between Lawrence Berkeley Laboratory (LBL), the Exxon Research and Engineering Company (EXXON), and the Stanford Synchrotron Radiation Laboratory (SSRL). Installation at SSRL will begin in the summer of 1982. The goal of this project is to provide extremely high-brightness synchrotron radiation beams over a broad spectral range from 50 eV to 40 keV. The radiation source is a 27 period (i.e., 55 pole) permanent magnet wiggler of a new design. The wiggler utilizes rare-earth cobalt (REC) material in the steel hybrid configuration to achieve high magnetic fields with short periods. An analysis has been made of the polarization, angular distribution and power density of the radiation produced by the wiggler. Details of the wiggler design are presented. The magnet is outside a thin walled (1mm) variable gap stainless steel vacuum chamber. The chamber gap will be opened to 1.8 cm for beam injection into SPEAR and then closed to 1.0 cm (or less) for operation. Five remotely controlled drives are provided; to change the wiggler gap, to change the vacuum chamber aperture and to position the wiggler. Details of the beam line optics and end stations are presented. Thermal loading on beam line components is severe. The peak power density at 7.5 m is 5 kW/cm 2 for the nominal wiggler field and present SPEAR beam currents and will approach 20 kW/cm 2 with the maximum wiggler field and projected SPEAR beam currents

The H line: a brand new beam line for fundamental physics at the J-PARC muon facility

International Nuclear Information System (INIS)

Kawamura, N; Shimomura, K; Miyake, Y; Toyoda, A; Saito, N; Mihara, S; Aoki, M

2013-01-01

The muon facility, J-PARC (Muon Science Establishment; MUSE), has been operated since first beam in 2008. Starting with a 200 kW proton beam, the beam intensity has reached 3×10 6 / muons/s, the most intense pulsed muon beam in the world. A 2 cm thick graphite target permits the extraction of four secondary muon beams. A brand new beam line, the H line, is planned to be constructed. The new beam line is designed to have a large acceptance, will provide the ability to tune the momentum, and use a kicker magnet and/or Wien filter. This beam line will provide an intense beam for experiments that require high statistics and must occupy the experimental areas for a relatively long period.

Beam diagnostics for Laser-induced proton generation at KAERI

International Nuclear Information System (INIS)

Kim, Dong Heun; Park, Seong Hee; Jeong, Young Uk; Lee, Ki Tae; Chan, Young Ho; Lee, Byung Cheol; Yoo, Byeong Duk

2005-01-01

With an advent of femto-second lasers, a laseraccelerated ion generation has been world-widely studied for medical and nuclear applications. It is known that protons with the energy from several tens MeV to a few hundreds MeV require for a cancer therapy and nuclear reaction. Even though, up to present, the maximum energy of laser-accelerated proton is about 60 MeV, it is expected that the energy of protons generated can be obtained at least up to 150 MeV. According to theoretical and experimental works, it turns out the energy distribution and the flux of ions strongly depends on the intensity of a fs laser at a target. However, physics on laser-plasma interaction is still not clear. The precise measurements of parameters of a fs laser and ions are important to figure out the physics and develop the theoretical interpretation. Typically, beam diagnostic system includes measurements and/or monitoring of the temporal and spatial profiles of lasers at the target as well as the energy spectrum and density profile of protons, which are critical for the analysis of mechanism and the characterization of protons generated. We fabricated and installed the target chamber for laser-accelerated proton generation and are now integrating beam diagnostic system. For laser diagnostics, beam monitoring and alignment system has been installed. For a charged particle, CR-39 detectors, Thomson parabola spectrometer, and Si charged particle detectors are installed for density profile and energy spectrum. In this paper, we discuss the laser beam monitoring and alignment system. We also estimates expected spectrum of protons from Thomson parabola spectrometer, depending on the parameters of protons

Dynamics and transport of laser-accelerated particle beams

International Nuclear Information System (INIS)

Becker, Stefan

2010-01-01

The subject of this thesis is the investigation and optimization of beam transport elements in the context of the steadily growing field of laser-driven particle acceleration. The first topic is the examination of the free vacuum expansion of an electron beam at high current density. It could be shown that particle tracking codes which are commonly used for the calculation of space charge effects will generate substantial artifacts in the regime considered here. The artifacts occurring hitherto predominantly involve insufficient prerequisites for the Lorentz transformation, the application of inadequate initial conditions and non negligible retardation artifacts. A part of this thesis is dedicated to the development of a calculation approach which uses a more adequate ansatz calculating space charge effects for laser-accelerated electron beams. It can also be used to validate further approaches for the calculation of space charge effects. The next elements considered are miniature magnetic quadrupole devices for the focusing of charged particle beams. General problems involved with their miniaturization concern distorting higher order field components. If these distorting components cannot be controlled, the field of applications is very limited. In this thesis a new method for the characterization and compensation of the distorting components was developed, which might become a standard method when assembling these permanent magnet multipole devices. The newly developed characterization method has been validated at the Mainz Microtron (MAMI) electron accelerator. Now that we can ensure optimum performance, the first application of permanent magnet quadrupole devices in conjunction with laser-accelerated ion beams is presented. The experiment was carried out at the Z-Petawatt laser system at Sandia National Laboratories. A promising application for laser-accelerated electron beams is the FEL in a university-scale size. The first discussion of all relevant aspects

Dynamics and transport of laser-accelerated particle beams

Energy Technology Data Exchange (ETDEWEB)

Becker, Stefan

2010-04-19

The subject of this thesis is the investigation and optimization of beam transport elements in the context of the steadily growing field of laser-driven particle acceleration. The first topic is the examination of the free vacuum expansion of an electron beam at high current density. It could be shown that particle tracking codes which are commonly used for the calculation of space charge effects will generate substantial artifacts in the regime considered here. The artifacts occurring hitherto predominantly involve insufficient prerequisites for the Lorentz transformation, the application of inadequate initial conditions and non negligible retardation artifacts. A part of this thesis is dedicated to the development of a calculation approach which uses a more adequate ansatz calculating space charge effects for laser-accelerated electron beams. It can also be used to validate further approaches for the calculation of space charge effects. The next elements considered are miniature magnetic quadrupole devices for the focusing of charged particle beams. General problems involved with their miniaturization concern distorting higher order field components. If these distorting components cannot be controlled, the field of applications is very limited. In this thesis a new method for the characterization and compensation of the distorting components was developed, which might become a standard method when assembling these permanent magnet multipole devices. The newly developed characterization method has been validated at the Mainz Microtron (MAMI) electron accelerator. Now that we can ensure optimum performance, the first application of permanent magnet quadrupole devices in conjunction with laser-accelerated ion beams is presented. The experiment was carried out at the Z-Petawatt laser system at Sandia National Laboratories. A promising application for laser-accelerated electron beams is the FEL in a university-scale size. The first discussion of all relevant aspects

Automatic tracking of the intersection of a laser and electron beam

International Nuclear Information System (INIS)

Turko, B.T.; Fuzesy, R.Z.; Pripstein, D.A.; Kowitt, M.; Chamberlain, O.; Shapiro, G.; Hughes, E.

1990-05-01

For the Compton Polarimeter experiment at the Stanford Linear Accelerator the crossing point of a laser beam and an electron beam must be kept accurate and stable. An electronic system is described for the automatic tracking and correcting of the beam crossing. A remote CCD camera, relatively insensitive to electromagnetic disturbance, records small displacements of the pulsed laser beam. Video signals are analyzed at a remote station, the amount of drift from a selected reference point determined and the appropriate correction commands sent to the motorized mirror deflecting the laser beam. A description of the system, its performance and the test results are presented. 2 refs., 4 figs

Beam conditioner for free electron lasers and synchrotrons

International Nuclear Information System (INIS)

Liu, H.; Neil, G.R.

1998-01-01

A focused optical has been used to introduce an optical pulse, or electromagnetic wave, collinear with the electron beam in a free electron laser or synchrotron thereby adding an axial field component that accelerates the electrons on the radial outside of the distribution of electrons in the electron beam. This invention consists of using the axial electrical component of a TEM 10 mode Gaussian beam in vacuum to condition the electron beam and speed up the outer electrons in the beam. The conditioning beam should possess about the same diameter as the electron beam. The beam waist of the conditioning wave must be located around the entrance of the undulator longitudinally to have a net energy exchange between the electrons in the outer part of the distribution and the conditioning wave owing to the natural divergence of a Gaussian beam. By accelerating the outer electrons, the outer and core electrons are caused to stay in phase. This increases the fraction of the electron beam energy that is converted to light thereby improving the efficiency of conversion of energy to light and therefore boosting the power output of the free electron laser and synchrotron. 4 figs

Using harmonic oscillators to determine the spot size of Hermite-Gaussian laser beams

Science.gov (United States)

Steely, Sidney L.

1993-01-01

The similarity of the functional forms of quantum mechanical harmonic oscillators and the modes of Hermite-Gaussian laser beams is illustrated. This functional similarity provides a direct correlation to investigate the spot size of large-order mode Hermite-Gaussian laser beams. The classical limits of a corresponding two-dimensional harmonic oscillator provide a definition of the spot size of Hermite-Gaussian laser beams. The classical limits of the harmonic oscillator provide integration limits for the photon probability densities of the laser beam modes to determine the fraction of photons detected therein. Mathematica is used to integrate the probability densities for large-order beam modes and to illustrate the functional similarities. The probabilities of detecting photons within the classical limits of Hermite-Gaussian laser beams asymptotically approach unity in the limit of large-order modes, in agreement with the Correspondence Principle. The classical limits for large-order modes include all of the nodes for Hermite Gaussian laser beams; Sturm's theorem provides a direct proof.

On the mutual interaction between laser beams in plasmas

International Nuclear Information System (INIS)

Ren, C.; Duda, B.J.; Evans, R.G.; Fonseca, R.A.; Hemker, R.G.; Mori, W.B.

2002-01-01

The nonlinear interaction between light beams in a plasma is studied. In particular, nonlinearities due to relativistic mass corrections and density modulations from a plasma wave wake are considered; but the results can be generalized for other nonlinearities. A simple physical picture using the nonlinear phase velocity of the light wave in a plasma is developed to show that when two laser beams are coherent, the force can be repulsive or attractive, depending on their relative phase. When the two laser beams are polarized in mutually perpendicular directions, the force is always attractive. Using a variational method, a simple analytical expression for this attractive force is derived for Gaussian beams. The centers of the lasers move analogously to point masses under this attractive force with the laser power playing the role of the mass. Under an attractive force, solutions exist where the two lasers can spiral around each other. It is also shown that the plasma wave wake can cause the two spiraling lasers to become intertwined forming a braided pattern. The braiding is common to any nonlinearity which is not instantaneous. The analytical results concerning attraction, repulsion, and braiding have been confirmed using three dimensional particle-in-cell simulations. The simulations also show that angular momentum can radiate away leading to the coalescence of the remaining energy

Self-reconstruction of diffraction-free and accelerating laser beams in scattering media

International Nuclear Information System (INIS)

Ersoy, T.; Yalizay, B.; Akturk, S.

2012-01-01

We experimentally investigate propagation of laser beams with different intensity profiles in highly scattering media. We generate transverse laser amplitude profiles with Gaussian, Bessel and Airy function envelopes. We then propagate these beams through optical phantoms formed with variable density intralipid solutions. At the sample exit, we compare change in maximum intensities, as well as beam profile reconstruction. We show that self-reconstruction properties of Bessel and Airy beams bring about slower decrease in maximum intensity with increasing scatterer density. On the other hand, the beam profiles deteriorate faster, as compared to reference Gaussian beams. Slower decrease in the intensity can be attributed to the wavevector spectra providing a continuous flow of energy to the beam center, while beam deterioration is linked to total beam volume in the scattering medium. These results show that beam shaping methods can significantly enhance delivery of intense light deeper into turbid media, but this enhancement is compromised by stronger speckling of beam profiles. -- Highlights: ► We experimentally investigate propagation of shaped laser beams in turbid media. ► Peak intensity of Bessel and Airy beams decrease slower with increasing scatterer. ► Shaped beam profiles deteriorate faster, as compared to reference Gaussian beams. ► Shaped beam profiles can enhance applications of lasers inscattering media.

Laser Beam Caustic Measurement with Focal Spot Analyser

DEFF Research Database (Denmark)

Olsen, Flemming Ove; Gong, Hui; Bagger, Claus

2005-01-01

In industrial applications of high power CO2-lasers the caustic characteristics of the laser beam have great effects on the performance of the lasers. A welldefined high intense focused spot is essential for reliable production results. This paper presents a focal spot analyser that is developed...

Investigation of Beam Emittance and Beam Transport Line Optics on Polarization

Energy Technology Data Exchange (ETDEWEB)

Fiedler, Andrew [Northern Illinois U.; Syphers, Michael [Fermilab

2017-10-06

Effects of beam emittance, energy spread, optical parameters and magnet misalignment on beam polarization through particle transport systems are investigated. Particular emphasis will be placed on the beam lines being used at Fermilab for the development of the muon beam for the Muon g-2 experiment, including comparisons with the natural polarization resulting from pion decay, and comments on the development of systematic correlations among phase space variables.

Efficiency of laser beam utilization in gas laser cutting of materials

Science.gov (United States)

Galushkin, M. G.; Grishaev, R. V.

2018-02-01

Relying on the condition of dynamic matching of the process parameters in gas laser cutting, the dependence of the beam utilization factor on the cutting speed and the beam power has been determined. An energy balance equation has been derived for a wide range of cutting speed values.

Measuring a Fiber-Optic Delay Line Using a Mode-Locked Laser

Science.gov (United States)

Tu, Meirong; McKee, Michael R.; Pak, Kyung S.; Yu, Nan

2010-01-01

The figure schematically depicts a laboratory setup for determining the optical length of a fiber-optic delay line at a precision greater than that obtainable by use of optical time-domain reflectometry or of mechanical measurement of length during the delay-line-winding process. In this setup, the delay line becomes part of the resonant optical cavity that governs the frequency of oscillation of a mode-locked laser. The length can then be determined from frequency-domain measurements, as described below. The laboratory setup is basically an all-fiber ring laser in which the delay line constitutes part of the ring. Another part of the ring - the laser gain medium - is an erbium-doped fiber amplifier pumped by a diode laser at a wavelength of 980 nm. The loop also includes an optical isolator, two polarization controllers, and a polarizing beam splitter. The optical isolator enforces unidirectional lasing. The polarization beam splitter allows light in only one polarization mode to pass through the ring; light in the orthogonal polarization mode is rejected from the ring and utilized as a diagnostic output, which is fed to an optical spectrum analyzer and a photodetector. The photodetector output is fed to a radio-frequency spectrum analyzer and an oscilloscope. The fiber ring laser can generate continuous-wave radiation in non-mode-locked operation or ultrashort optical pulses in mode-locked operation. The mode-locked operation exhibited by this ring is said to be passive in the sense that no electro-optical modulator or other active optical component is used to achieve it. Passive mode locking is achieved by exploiting optical nonlinearity of passive components in such a manner as to obtain ultra-short optical pulses. In this setup, the particular nonlinear optical property exploited to achieve passive mode locking is nonlinear polarization rotation. This or any ring laser can support oscillation in multiple modes as long as sufficient gain is present to overcome

Study of fast electron generation using multi beam of LFEX-class laser

International Nuclear Information System (INIS)

Hata, M; Nagatomo, H; Sakagami, H; Johzaki, T; Sentoku, Y

2016-01-01

Fast Ignition Realization Experiment project phase-I (FIREX-I) is being performed at Institute of Laser Engineering, Osaka University. In this project, the four-beam bundled high-energy Petawatt laser (LFEX) is being operated. LFEX laser provides great multi-beam irradiation flexibility, with the possibility of arrange the pulses in temporal sequence, spatially separate them in distinct spots of focus them in a single spot. In this paper, we study the two- beam interference effects on high-intensity picosecond laser-plasma interaction (LPI) by twodimensional relativistic Particle-In-Cell simulations. The interference causes surface perturbation, which enhances laser absorption and underdense plasma generation, increasing the accelerated electron number and their slope temperature. The laser-to-electron energy conversion efficiency for two-beam interference case is suitable for Fast Ignition (FI) compared to the single beam case, but the increment of fast electron divergence leads to lower energy coupling. To optimize the target design for FI, these interference effects should be taken into consideration. (paper)

On the exploration of effect of critical beam power on the propagation of Gaussian laser beam in collisionless magnetized plasma

Science.gov (United States)

Urunkar, T. U.; Valkunde, A. T.; Vhanmore, B. D.; Gavade, K. M.; Patil, S. D.; Takale, M. V.

2018-05-01

It is quite known that critical power of the laser plays vital role in the propagation of Gaussian laser beam in collisionless plasma. The nonlinearity in dielectric constant considered herein is due to the ponderomotive force. In the present analysis, the interval of critical beam power has been explored to sustain the competition between diffraction and self-focusing of Gaussian laser beam during propagation in collisionless magnetized plasma. Differential equation for beam-width parameter has been established by using WKB and paraxial approximations under parabolic equation approach. The effect of critical power on the propagation of Gaussian laser beam has been presented graphically and discussed.

Observation of laser multiple filamentation process and multiple electron beams acceleration in a laser wakefield accelerator

International Nuclear Information System (INIS)

Li, Wentao; Liu, Jiansheng; Wang, Wentao; Chen, Qiang; Zhang, Hui; Tian, Ye; Zhang, Zhijun; Qi, Rong; Wang, Cheng; Leng, Yuxin; Li, Ruxin; Xu, Zhizhan

2013-01-01

The multiple filaments formation process in the laser wakefield accelerator (LWFA) was observed by imaging the transmitted laser beam after propagating in the plasma of different density. During propagation, the laser first self-focused into a single filament. After that, it began to defocus with energy spreading in the transverse direction. Two filaments then formed from it and began to propagate independently, moving away from each other. We have also demonstrated that the laser multiple filamentation would lead to the multiple electron beams acceleration in the LWFA via ionization-induced injection scheme. Besides, its influences on the accelerated electron beams were also analyzed both in the single-stage LWFA and cascaded LWFA

Rippled beam free electron laser amplifier

Science.gov (United States)

Carlsten, Bruce E.

1999-01-01

A free electron laser amplifier provides a scalloping annular electron beam that interacts with the axial electric field of a TM.sub.0n mode. A waveguide defines an axial centerline and, a solenoid arranged about the waveguide produces an axial constant magnetic field within the waveguide. An electron beam source outputs a annular electron beam that interacts with the axial magnetic field to have an equilibrium radius and a ripple radius component having a variable radius with a ripple period along the axial centerline. An rf source outputs an axial electric field that propagates within the waveguide coaxial with the electron beam and has a radial mode that interacts at the electron beam at the equilibrium radius component of the electron beam.

Structure and properties of optical-discharge plasma in CO2-laser beam near target surface

Science.gov (United States)

Danshchikov, Ye. V.; Dymshakov, V. A.; Lebedev, F. V.; Ryazanov, A. V.

1986-05-01

An experimental study of optical-discharge plasma in a CO2-laser beam at a target surface was made for the purpose of exploring the not yet understood role of this plasma in the laser-target interaction process. Such a plasma was produced by means of a quasi-continuous CO2-laser with an unstable resonator, its power being maintained constant for 1 ms periods. Its radiation was focused on the surfaces of thick and seeding thin Al, Ti, and Ta targets inclined at an approximately 70 deg. angle to the beam, inside a hermetic chamber containing air, argon, or helium under atmospheric pressure. The radiation intensity distribution over the focal plane and the nearest caustic surface in the laser beam was measured along with the plasma parameters, the latter by the methods of spectral analysis and photoelectric recording. The instrumentation for this purpose included an MDR-3 monochromator with an entrance slit, a double electron-optical converter, a memory oscillograph, and an SI-10-30 ribbon lamp as radiation reference standard. The results yielded integral diametral intensity distributions of the emission lines Ti-II (457.2 nm), Ti-I (464 nm), Ar-II (462 nm), radial and axial temperature profiles of optical discharge in metal vapor in surrounding gas, and the radial temperature profile of irradiated metal surface at successive instants of time. The results reveal marked differences between the structures and the properties of optical-discharge plasma in metal vapor and in surrounding gas, optical discharge in the former being characterized by localization within the laser beam and optical discharge in the latter being characterized by a drift away from the target.

Fluid simulation for two laser beams co-propagating in underdense plasma

International Nuclear Information System (INIS)

Mahdy, A.I.

2004-09-01

2D simulations code was constructed in order simulate the interactions of two co-propagating laser beams with underdense plasma. Simulations results at different laser intensities and separation-distances between the beams centroids were presented. In the results the effects of the laser intensities on the self-focusing and merging of the propagating beams were shown. In addition, the influence of increasing the separation-distance on the beams stability and trajectories were studied. A comparison with previous simulations at similar conditions was carried out in order to evaluate the numerical technique used to solve the basic equations. (author)

Magnet power supply and beam line control for a secondary beam line K6

International Nuclear Information System (INIS)

Suzuki, Y.; Takasaki, M.; Minakawa, M.; Ishii, H.; Kato, Y.; Ieiri, M.; Tanaka, K.H.; Noumi, H.; Yamanoi, Y.

1992-01-01

K6 is a secondary separated-beam line with momentum range up to 2.0 GeV/c in the north experimental hall at the KEK 12 GeV Proton Synchrotron (KEK-PS). On the construction, newly developed magnet power supplies (MPSs), in each of them a microprocessor is embedded, are introduced. The features of the MPS are as follows: 1, The MPS is connected to an upper-level beam line controller (BLC) by GPIB highway for exchanging simple messages. 2, All the operations of the MPS are supervised by the microprocessor, which has its individual parameters and fault messages. It reduces the load of the upper-level controller. 3, The MPS has functions to inspect itself and to report the result. It saves much time and labor of maintenance. (author)

Laser ionization installation for measurement of atomic beam parameters

CERN Document Server

Tukhlibaev, O; Khalilov, E E; Alimov, U Z

2002-01-01

The design of the laser ionization installation for determination of the atomic beam intensity, density and spatial structure is described. The method of the atoms laser resonance staged photoionization is applied in the installation. The above installation consists of two lasers on the dyestuffs, the atomizer, the ionization system and the ion signals registration system. The results of studies on the spatial structure of the In atoms beam are presented. The proposed method provides for the spatial resolution at the level of 10-100 mu m

Beam collimation and energy spectrum compression of laser-accelerated proton beams using solenoid field and RF cavity

Energy Technology Data Exchange (ETDEWEB)

Teng, J.; Gu, Y.Q., E-mail: tengjian@mail.ustc.edu.cn; Zhu, B.; Hong, W.; Zhao, Z.Q.; Zhou, W.M.; Cao, L.F.

2013-11-21

This paper presents a new method of laser produced proton beam collimation and spectrum compression using a combination of a solenoid field and a RF cavity. The solenoid collects laser-driven protons efficiently within an angle that is smaller than 12 degrees because it is mounted few millimeters from the target, and collimates protons with energies around 2.3 MeV. The collimated proton beam then passes through a RF cavity to allow compression of the spectrum. Particle-in-cell (PIC) simulations demonstrate the proton beam transport in the solenoid and RF electric fields. Excellent energy compression and collection efficiency of protons are presented. This method for proton beam optimization is suitable for high repetition-rate laser acceleration proton beams, which could be used as an injector for a conventional proton accelerator.

Beam collimation and energy spectrum compression of laser-accelerated proton beams using solenoid field and RF cavity

Science.gov (United States)

Teng, J.; Gu, Y. Q.; Zhu, B.; Hong, W.; Zhao, Z. Q.; Zhou, W. M.; Cao, L. F.

2013-11-01

This paper presents a new method of laser produced proton beam collimation and spectrum compression using a combination of a solenoid field and a RF cavity. The solenoid collects laser-driven protons efficiently within an angle that is smaller than 12 degrees because it is mounted few millimeters from the target, and collimates protons with energies around 2.3 MeV. The collimated proton beam then passes through a RF cavity to allow compression of the spectrum. Particle-in-cell (PIC) simulations demonstrate the proton beam transport in the solenoid and RF electric fields. Excellent energy compression and collection efficiency of protons are presented. This method for proton beam optimization is suitable for high repetition-rate laser acceleration proton beams, which could be used as an injector for a conventional proton accelerator.

Beam collimation and energy spectrum compression of laser-accelerated proton beams using solenoid field and RF cavity

International Nuclear Information System (INIS)

Teng, J.; Gu, Y.Q.; Zhu, B.; Hong, W.; Zhao, Z.Q.; Zhou, W.M.; Cao, L.F.

2013-01-01

This paper presents a new method of laser produced proton beam collimation and spectrum compression using a combination of a solenoid field and a RF cavity. The solenoid collects laser-driven protons efficiently within an angle that is smaller than 12 degrees because it is mounted few millimeters from the target, and collimates protons with energies around 2.3 MeV. The collimated proton beam then passes through a RF cavity to allow compression of the spectrum. Particle-in-cell (PIC) simulations demonstrate the proton beam transport in the solenoid and RF electric fields. Excellent energy compression and collection efficiency of protons are presented. This method for proton beam optimization is suitable for high repetition-rate laser acceleration proton beams, which could be used as an injector for a conventional proton accelerator

Laser-driven electron beam and radiation sources for basic, medical and industrial sciences

Science.gov (United States)

NAKAJIMA, Kazuhisa

2015-01-01

To date active research on laser-driven plasma-based accelerators have achieved great progress on production of high-energy, high-quality electron and photon beams in a compact scale. Such laser plasma accelerators have been envisaged bringing a wide range of applications in basic, medical and industrial sciences. Here inheriting the groundbreaker’s review article on “Laser Acceleration and its future” [Toshiki Tajima, (2010)],1) we would like to review recent progress of producing such electron beams due to relativistic laser-plasma interactions followed by laser wakefield acceleration and lead to the scaling formulas that are useful to design laser plasma accelerators with controllability of beam energy and charge. Lastly specific examples of such laser-driven electron/photon beam sources are illustrated. PMID:26062737

Laser ablation of hard tissue: correlation between the laser beam parameters and the post-ablative tissue characteristics

Science.gov (United States)

Serafetinides, Alexandros A.; Makropoulou, Mersini I.; Khabbaz, Maruan

2003-11-01

Hard dental tissue laser applications, such as preventive treatment, laser diagnosis of caries, laser etching of enamel, laser decay removal and cavity preparation, and more recently use of the laser light to enlarge the root canal during the endodontic therapy, have been investigated for in vitro and in vivo applications. Post-ablative surface characteristics, e.g. degree of charring, cracks and other surface deformation, can be evaluated using scanning electron microscopy. The experimental data are discussed in relevance with the laser beam characteristics, e.g. pulse duration, beam profile, and the beam delivery systems employed. Techniques based on the laser illumination of the dental tissues and the subsequent evaluation of the scattered fluorescent light will be a valuable tool in early diagnosis of tooth diseases, as carious dentin or enamel. The laser induced autofluorescence signal of healthy dentin is much stronger than that of the carious dentin. However, a better understanding of the transmission patterns of laser light in teeth, for both diagnosis and therapy is needed, before the laser procedures can be used in a clinical environment.

Single lens laser beam shaper

Science.gov (United States)

Liu, Chuyu [Newport News, VA; Zhang, Shukui [Yorktown, VA

2011-10-04

A single lens bullet-shaped laser beam shaper capable of redistributing an arbitrary beam profile into any desired output profile comprising a unitary lens comprising: a convex front input surface defining a focal point and a flat output portion at the focal point; and b) a cylindrical core portion having a flat input surface coincident with the flat output portion of the first input portion at the focal point and a convex rear output surface remote from the convex front input surface.

Table of laser lines in gases and vapors

Energy Technology Data Exchange (ETDEWEB)

Beck, R; Englisch, W; Guers, K

1980-01-01

Numerous applications of lasers require use of specific wavelengths (gas analysis including remote sensing, Raman spectroscopy, optical pumping, laser chemistry and isotope separation). Scientists active in these fields have been compelled to search, in addition to the available, mostly obsolete, laser-line tables, the entire recent literature in order to find suitable laser transitions. Over 6100 laser transitions are presented. An additional list of the lines arranged in order of wavelength should greatly facilitate the search for a laser material that generates a specific wavelength. Further information has also been supplied by listing the pump transition for each of the FIR lines obtained with the optically pumped organic vapors. In addition to the laser lines, the operating conditions under which emission has been achieved are briefly specified at the top of the list for each active medium. The order in which the atomic laser media are listed is based on the periodic system, beginning with the noble gases, continuing with hydrogen and the alkalies to the halogens and the rare earths. The molecular laser media are arranged in order of chemical composition, beginning with the compounds of noble gases (the excimers), then other diatomic molecules, triatomic molecules, and ending with the more complex molecules of organic vapors. (WHK).

Coherent beam combining architectures for high power tapered laser arrays

Science.gov (United States)

Schimmel, G.; Janicot, S.; Hanna, M.; Decker, J.; Crump, P.; Erbert, G.; Witte, U.; Traub, M.; Georges, P.; Lucas-Leclin, G.

2017-02-01

Coherent beam combining (CBC) aims at increasing the spatial brightness of lasers. It consists in maintaining a constant phase relationship between different emitters, in order to combine them constructively in one single beam. We have investigated the CBC of an array of five individually-addressable high-power tapered laser diodes at λ = 976 nm, in two architectures: the first one utilizes the self-organization of the lasers in an interferometric extended-cavity, which ensures their mutual coherence; the second one relies on the injection of the emitters by a single-frequency laser diode. In both cases, the coherent combining of the phase-locked beams is ensured on the front side of the array by a transmission diffractive grating with 98% efficiency. The passive phase-locking of the laser bar is obtained up to 5 A (per emitter). An optimization algorithm is implemented to find the proper currents in the five ridge sections that ensured the maximum combined power on the front side. Under these conditions we achieve a maximum combined power of 7.5 W. In the active MOPA configuration, we can increase the currents in the tapered sections up to 6 A and get a combined power of 11.5 W, corresponding to a combining efficiency of 76%. It is limited by the beam quality of the tapered emitters and by fast phase fluctuations between emitters. Still, these results confirm the potential of CBC approaches with tapered lasers to provide a high-power and high-brightness beam, and compare with the current state-of-the-art with laser diodes.

Direct diode lasers with comparable beam quality to fiber, CO2, and solid state lasers

Science.gov (United States)

Huang, Robin K.; Chann, Bien; Burgess, James; Kaiman, Michael; Overman, Robert; Glenn, John D.; Tayebati, Parviz

2012-03-01

TeraDiode has produced kW-class ultra-high brightness fiber-coupled direct diode lasers. A fiber-coupled direct diode laser with a power level of 2,040 W from a 50 μm core diameter, 0.15 numerical aperture (NA) output fiber at a single center wavelength was demonstrated. This was achieved with a novel beam combining and shaping technique using COTS diode lasers. The fiber-coupled output corresponds to a Beam Parameter Product (BPP) of 3.75 mm-mrad and is the lowest BPP kW-class direct diode laser yet reported. This laser is suitable for industrial materials processing applications, including sheet metal cutting and welding. This 2-kW fiber-coupled direct diode laser has comparable brightness to that of industrial fiber lasers and CO2 lasers, and is over 10x brighter than state-of-the-art direct diode lasers.

Optical breakdown of helium in Bessel laser radiation beams

International Nuclear Information System (INIS)

Andreev, N E; Pleshanov, I V; Margolin, L Ya; Pyatnitskii, Lev N

1998-01-01

Numerical simulation is used to investigate the dynamics of formation of a helium plasma in Bessel beams, shaped by an axicon and a phase converter from a laser radiation pulse with Gaussian temporal and radial intensity profiles. The beam intensities at the breakdown threshold are determined as a function of the pulse duration for various radial field distributions in a beam characterised by Bessel functions of order m (m = 0 - 5). It is shown that in the investigated range of parameters the threshold intensity is independent of m. The temporal and spatial evolution of the resultant plasma, and the dependence of the plasma characteristics on the pulse parameters are considered. Conditions are found for the formation of tubular plasma channels in beams of orders m≥1. The adopted model of the optical breakdown of helium is shown to be satisfactory because of a good agreement between the results of calculations of the moment of breakdown in a zeroth-order Bessel beam and experimental results. (interaction of laser radiation with matter. laser plasma)

A line beam electron gun for rapid thermal processing

Science.gov (United States)

Pauli, M.; Müller, J.; Hartkopf, K.; Barth, T.

1992-04-01

A line beam electron gun based on the Pierce gun type was developed. The line cathode was realized by a directly heated tungsten rod. The temperature distribution along the tungsten rod was simulated numerically. The simulation shows a flat temperature across 2/3 of the cathode length and it agrees with appropriate measurable parameters. The beam profiles of the electron gun perpendicular to the line direction were examined as a function of electrical and geometrical parameters: The space-charge distribution in front of the cathode was found to be responsible for the shape of the beam profile. The shape of the beam profile is weakly influenced by the acceleration to the anode. The heating current induced voltage drop along the cathode was found to be responsible for the nonuniform emission in line direction. A model for the emission behavior of the line beam electron gun was developed. The model is based on the results of the measurements and on a numerical simulation of the potential distribution in the area between Pierce reflectors and anode. The emission model shows a solution to homogenize the emission by a suitable variation of geometrical parameters in line direction. A linear variation was realized in experiment which enables a uniform emission across 2/3 of the cathode length. The beam profile is adjustable by a bias voltage between the cathode and the Pierce reflectors.

Characterization of the ELIMED Permanent Magnets Quadrupole system prototype with laser-driven proton beams

Science.gov (United States)

Schillaci, F.; Pommarel, L.; Romano, F.; Cuttone, G.; Costa, M.; Giove, D.; Maggiore, M.; Russo, A. D.; Scuderi, V.; Malka, V.; Vauzour, B.; Flacco, A.; Cirrone, G. A. P.

2016-07-01

Laser-based accelerators are gaining interest in recent years as an alternative to conventional machines [1]. In the actual ion acceleration scheme, energy and angular spread of the laser-driven beams are the main limiting factors for beam applications and different solutions for dedicated beam-transport lines have been proposed [2,3]. In this context a system of Permanent Magnet Quadrupoles (PMQs) has been realized [2] by INFN-LNS (Laboratori Nazionali del Sud of the Instituto Nazionale di Fisica Nucleare) researchers, in collaboration with SIGMAPHI company in France, to be used as a collection and pre-selection system for laser driven proton beams. This system is meant to be a prototype to a more performing one [3] to be installed at ELI-Beamlines for the collection of ions. The final system is designed for protons and carbons up to 60 MeV/u. In order to validate the design and the performances of this large bore, compact, high gradient magnetic system prototype an experimental campaign have been carried out, in collaboration with the group of the SAPHIR experimental facility at LOA (Laboratoire d'Optique Appliquée) in Paris using a 200 TW Ti:Sapphire laser system. During this campaign a deep study of the quadrupole system optics has been performed, comparing the results with the simulation codes used to determine the setup of the PMQ system and to track protons with realistic TNSA-like divergence and spectrum. Experimental and simulation results are good agreement, demonstrating the possibility to have a good control on the magnet optics. The procedure used during the experimental campaign and the most relevant results are reported here.

Simple and efficient method of spin-polarizing a metastable helium beam by diode laser optical pumping

International Nuclear Information System (INIS)

Granitza, B.; Salvietti, M.; Torello, E.; Mattera, L.; Sasso, A.

1995-01-01

Diode laser optical pumping to produce a highly spin-polarized metastable He beam to be used in a spin-polarized metastable atom deexcitation spectroscopy experiment on magnetized surfaces is described. Efficient pumping of the beam is performed by means of an SDL-6702 distributed Bragg reflector diode laser which yields 50 mW of output power in a single longitudinal mode at 1083 nm, the resonance wavelength for the 2 3 S→2 3 P 0,1,2 (D 0 , D 1 , and D 2 ) transitions of He*. The light is circularly polarized by a quarter-wave plate, allowing easy change of the sense of atomic polarization. The laser frequency can be locked to the atomic transition for several hours by phase-sensitive detection of the saturated absorption signal in a He discharge cell. Any of the three transitions of the triplet system can be pumped with the laser but the maximum level of atomic polarization of 98.5% is found pumping the D 2 line. copyright 1995 American Institute of Physics

Infrared laser scattering system for the plasma diagnostics: CO/sub 2/ laser characteristics

Energy Technology Data Exchange (ETDEWEB)

Hiraki, N; Kawasaki, S; Muraoka, K

1975-08-01

A detailed study was conducted of the operating characteristics of a double discharge infrared TEA carbon dioxide laser used for scattering measurements of plasmas. The discharge condition, the laser output energy and power, the beam profile and divergence, the emission spectral line width, the time lag and jitter of the output from the discharge trigger, have been established. It is concluded that the carbon dioxide oscillator can deliver the allowable beam divergence and spectral line width for the measurement of ion temperature in light scattering studies of theta pinch plasmas. The results presented might be applicable to laser fusion experiments using carbon dioxide lasers.

Glow-discharge-created electron beams and beam-excited lasers

International Nuclear Information System (INIS)

Meyer, J.D.

1989-01-01

Efficiently created glow discharge electron beams have been developed and studied in detail. The beam mode of operation occurs in the abnormal glow adjacent to the glow-to-arc transition regime. In contrast to electron beams generated in high vacuum from thermionic electron emitting sources, this type of discharge creates electrons directly in soft vacuum by secondary electron emission from cold cathode surfaces following the bombardment of the cathode surface by fast ions and neutral atoms. Factors influencing the efficient electron emission from cold cathodes are presented with emphasis on cathode materials. Sintered ceramic-metal cathodes and oxide-coated cathodes are presented, both of which can produce high power, efficiently generated, d.c. electron beams with discharge currents up to 1 amp (∼130 mA/cm 2 ) at volt ages of up to 6 kV. Novel cathode designs and discharge geometries are presented with specific emphasis on both self-focussed beams emitted from circular cathodes and line-source electron beams emitted from rectangular cathodes forming a thin sheet of electrons. Electrostatically focussed line-source electron beams are spatially characterized by experimentally measuring the effect of discharge parameters and cathode design upon the focussed beam width, focal point, and uniformity. This is achieved by scanning a current collecting detector in three dimensions in order to profile the distribution of electron beam current. Discharge electron beams are further characterized by their electron energy distribution. Measured electron flux energy distributions of transmitted beam electrons in the negative glow are compared to theoretical models. The relative effects of elastic and inelastic collisions mechanisms upon both the overall form and detailed structure of the energy distribution are discussed

Thermal problems on high flux beam lines

International Nuclear Information System (INIS)

Avery, R.T.

1983-09-01

Wiggler and undulator magnets can provide very intense photon flux densities to beam line components. This paper addresses some thermal/materials consequences due to such impingement. The LBL/Exxon/SSRL hybrid-wiggler Beam Line VI now nearing operation will be able to provide up to approx. 7 kW of total photon power at planned SPEAR operating conditions. The first masks are located at 6.5 meters from the source and may receive a peak power density (transverse to the beam) exceeding 20 kW/cm 2 . Significantly, this heat transfer rate exceeds that radiated from the sun's surface (7 kW/cm 2 ) and is comparable to that of welding torches. Clearing, cooling and configuration are of critical importance. Configurations for the first fixed mask, the movable mask, and the pivot mask on this beam line are presented together with considerations of thermal stress fatigue and of heat transfer by conduction to water-cooling circuits. Some preliminary information on heating of crystals and mirrors is also presented

Transport of laser accelerated proton beams and isochoric heating of matter

International Nuclear Information System (INIS)

Roth, M; Alber, I; Guenther, M; Harres, K; Bagnoud, V; Brown, C; Gregori, G; Clarke, R; Heathcote, R; Li, B; Daido, H; Fernandez, J; Flippo, K; Gaillard, S; Gauthier, C; Glenzer, S; Kritcher, A; Kugland, N; LePape, S; Makita, M

2010-01-01

The acceleration of intense proton and ion beams by ultra-intense lasers has matured to a point where applications in basic research and technology are being developed. Crucial for harvesting the unmatched beam parameters driven by the relativistic electron sheath is the precise control of the beam. We report on recent experiments using the PHELIX laser at GSI, the VULCAN laser at RAL and the TRIDENT laser at LANL to control and use laser accelerated proton beams for applications in high energy density research. We demonstrate efficient collimation of the proton beam using high field pulsed solenoid magnets, a prerequisite to capture and transport the beam for applications. Furthermore we report on two campaigns to use intense, short proton bunches to isochorically heat solid targets up to the warm dense matter state. The temporal profile of the proton beam allows for rapid heating of the target, much faster than the hydrodynamic response time thereby creating a strongly coupled plasma at solid density. The target parameters are then probed by X-ray Thomson scattering (XRTS) to reveal the density and temperature of the heated volume. This combination of two powerful techniques developed during the past few years allows for the generation and investigation of macroscopic samples of matter in states present in giant planets or the interior of the earth.

Transport of laser accelerated proton beams and isochoric heating of matter

Energy Technology Data Exchange (ETDEWEB)

Roth, M; Alber, I; Guenther, M; Harres, K [Inst. fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Bagnoud, V [GSI Helmholtzzentrum f. Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Brown, C; Gregori, G [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Clarke, R; Heathcote, R; Li, B [STFC, Rutherford Appleton Laboratory, Chilton, Didcot, OX14 OQX (United Kingdom); Daido, H [Photo Medical Research Center, JAEA, Kizugawa-City, Kyoto 619-0215 (Japan); Fernandez, J; Flippo, K; Gaillard, S; Gauthier, C [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Glenzer, S; Kritcher, A; Kugland, N; LePape, S [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Makita, M, E-mail: markus.roth@physik.tu-darmstadt.d [School of Mathematics and Physics, Queen' s University of Belfast, Belfast BT7 1NN (United Kingdom)

2010-08-01

The acceleration of intense proton and ion beams by ultra-intense lasers has matured to a point where applications in basic research and technology are being developed. Crucial for harvesting the unmatched beam parameters driven by the relativistic electron sheath is the precise control of the beam. We report on recent experiments using the PHELIX laser at GSI, the VULCAN laser at RAL and the TRIDENT laser at LANL to control and use laser accelerated proton beams for applications in high energy density research. We demonstrate efficient collimation of the proton beam using high field pulsed solenoid magnets, a prerequisite to capture and transport the beam for applications. Furthermore we report on two campaigns to use intense, short proton bunches to isochorically heat solid targets up to the warm dense matter state. The temporal profile of the proton beam allows for rapid heating of the target, much faster than the hydrodynamic response time thereby creating a strongly coupled plasma at solid density. The target parameters are then probed by X-ray Thomson scattering (XRTS) to reveal the density and temperature of the heated volume. This combination of two powerful techniques developed during the past few years allows for the generation and investigation of macroscopic samples of matter in states present in giant planets or the interior of the earth.

Beam delivery system with a non-digitized diffractive beam splitter for laser-drilling of silicon

Science.gov (United States)

Amako, J.; Fujii, E.

2016-02-01

We report a beam-delivery system consisting of a non-digitized diffractive beam splitter and a Fourier transform lens. The system is applied to the deep-drilling of silicon using a nanosecond pulse laser in the manufacture of inkjet printer heads. In this process, a circularly polarized pulse beam is divided into an array of uniform beams, which are then delivered precisely to the process points. To meet these requirements, the splitter was designed to be polarization-independent with an efficiency>95%. The optical elements were assembled so as to allow the fine tuning of the effective overall focal length by adjusting the wavefront curvature of the beam. Using the system, a beam alignment accuracy ofbeam array and the throughput was substantially improved (10,000 points on a silicon wafer drilled in ~1 min). This beam-delivery scheme works for a variety of laser applications that require parallel processing.

Measurement system with high accuracy for laser beam quality.

Science.gov (United States)

Ke, Yi; Zeng, Ciling; Xie, Peiyuan; Jiang, Qingshan; Liang, Ke; Yang, Zhenyu; Zhao, Ming

2015-05-20

Presently, most of the laser beam quality measurement system collimates the optical path manually with low efficiency and low repeatability. To solve these problems, this paper proposed a new collimated method to improve the reliability and accuracy of the measurement results. The system accuracy controlled the position of the mirror to change laser beam propagation direction, which can realize the beam perpendicularly incident to the photosurface of camera. The experiment results show that the proposed system has good repeatability and the measuring deviation of M2 factor is less than 0.6%.

Using a short-pulse diffraction-limited laser beam to probe filamentation of a random phase plate smoothed beam

International Nuclear Information System (INIS)

Kline, J. L.; Montgomery, D. S.; Flippo, K. A.; Johnson, R. P.; Rose, H. A.; Shimada, T.; Williams, E. A.

2008-01-01

A short pulse (few picoseconds) laser probe provides high temporal resolution measurements to elucidate details of fast dynamic phenomena not observable with typical longer laser pulse probes and gated diagnostics. Such a short pulse laser probe (SPLP) has been used to measure filamentation of a random phase plate (RPP) smoothed laser beam in a gas-jet plasma. The plasma index of refraction due to driven density and temperature fluctuations by the RPP beam perturbs the phase front of a SPLP propagating at a 90 deg. angle with respect to the RPP interaction beam. The density and temperature fluctuations are quasistatic on the time scale of the SPLP (∼2 ps). The transmitted near-field intensity distribution from the SPLP provides a measure of the phase front perturbation. At low plasma densities, the transmitted intensity pattern is asymmetric with striations across the entire probe beam in the direction of the RPP smoothed beam. As the plasma density increases, the striations break up into smaller sizes along the direction of the RPP beam propagation. The breakup of the intensity pattern is consistent with self-focusing of the RPP smoothed interaction beam. Simulations of the experiment using the wave propagation code, PF3D, are in qualitative agreement demonstrating that the asymmetric striations can be attributed to the RPP driven density fluctuations. Quantification of the beam breakup measured by the transmitted SPLP could lead to a new method for measuring self-focusing of lasers in underdense plasmas.

Using a short-pulse diffraction-limited laser beam to probe filamentation of a random phase plate smoothed beam.

Science.gov (United States)

Kline, J L; Montgomery, D S; Flippo, K A; Johnson, R P; Rose, H A; Shimada, T; Williams, E A

2008-10-01

A short pulse (few picoseconds) laser probe provides high temporal resolution measurements to elucidate details of fast dynamic phenomena not observable with typical longer laser pulse probes and gated diagnostics. Such a short pulse laser probe (SPLP) has been used to measure filamentation of a random phase plate (RPP) smoothed laser beam in a gas-jet plasma. The plasma index of refraction due to driven density and temperature fluctuations by the RPP beam perturbs the phase front of a SPLP propagating at a 90 degree angle with respect to the RPP interaction beam. The density and temperature fluctuations are quasistatic on the time scale of the SPLP (approximately 2 ps). The transmitted near-field intensity distribution from the SPLP provides a measure of the phase front perturbation. At low plasma densities, the transmitted intensity pattern is asymmetric with striations across the entire probe beam in the direction of the RPP smoothed beam. As the plasma density increases, the striations break up into smaller sizes along the direction of the RPP beam propagation. The breakup of the intensity pattern is consistent with self-focusing of the RPP smoothed interaction beam. Simulations of the experiment using the wave propagation code, PF3D, are in qualitative agreement demonstrating that the asymmetric striations can be attributed to the RPP driven density fluctuations. Quantification of the beam breakup measured by the transmitted SPLP could lead to a new method for measuring self-focusing of lasers in underdense plasmas.

Vertical laser beam propagation through the troposphere

Science.gov (United States)

Minott, P. O.; Bufton, J. L.; Schaefer, W. H.; Grolemund, D. A.

1974-01-01

The characteristics of the earth's atmosphere and its effects upon laser beams was investigated in a series of balloon borne, optical propagation experiments. These experiments were designed to simulate the space to ground laser link. An experiment to determine the amplitude fluctuation, commonly called scintillation, caused by the atmosphere was described.

Experimental Program for the CLIC test facility 3 test beam line

CERN Document Server

Adli, E; Dobert, S; Olvegaard, M; Schulte, D; Syratchev, I; Lillestol, Reidar

2010-01-01

The CLIC Test Facility 3 Test Beam Line is the first prototype for the CLIC drive beam decelerator. Stable transport of the drive beam under deceleration is a mandatory component in the CLIC two-beam scheme. In the Test Beam Line more than 50% of the total energy will be extracted from a 150 MeV, 28 A electron drive beam, by the use of 16 power extraction and transfer structures. A number of experiments are foreseen to investigate the drive beam characteristics under deceleration in the Test Beam Line, including beam stability, beam blow up and the efficiency of the power extraction. General benchmarking of decelerator simulation and theory studies will also be performed. Specially designed instrumentation including precision BPMs, loss monitors and a time-resolved spectrometer dump will be used for the experiments. This paper describes the experimental program foreseen for the Test Beam Line, including the relevance of the results for the CLIC decelerator studies.

On-line iron ore slurry monitoring using laser induced plasma spectroscopy

International Nuclear Information System (INIS)

Barrette, L.; Turmel, S.; Boivin, J.-A.; Sabsabi, M.; Martinovic, T.I.; Ouellet, G.

1999-01-01

In response to the need for a better control [Lb1] of the various additives used in the iron ore pellet making process, Laser-Induced Plasma Spectroscopy (LIPS) has been tested for the on-line monitoring of Si, AI, Ca, Mg, and C. This work shows that factors such as laser beam focusing, particle size, slurry density and mineralogical composition have to be taken into account to meet precision and accuracy requirements. An internal standardization (peak ratio) and an original multivariate calibration technique based on fuzzy logic concepts [Lb2] are [Lb3] used to minimize the effect of these factors. This paper describes the experimental set-up, the effect of influence factors and the results obtained both in the laboratory and in an iron ore plant. (author)

Hollow core waveguide as mid-infrared laser modal beam filter

Energy Technology Data Exchange (ETDEWEB)

Patimisco, P.; Giglio, M.; Spagnolo, V. [Dipartimento Interateneo di Fisica, Università e Politecnico di Bari, CNR-IFN UOS BARI, Via Amendola 173, 70126 Bari (Italy); Sampaolo, A. [Dipartimento Interateneo di Fisica, Università e Politecnico di Bari, CNR-IFN UOS BARI, Via Amendola 173, 70126 Bari (Italy); Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, Texas 77005 (United States); Kriesel, J. M. [Opto-Knowledge Systems, Inc. (OKSI), 19805 Hamilton Ave., Torrance, California 90502-1341 (United States); Tittel, F. K. [Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, Texas 77005 (United States)

2015-09-21

A novel method for mid-IR laser beam mode cleaning employing hollow core waveguide as a modal filter element is reported. The influence of the input laser beam quality on fiber optical losses and output beam profile using a hollow core waveguide with 200 μm-bore size was investigated. Our results demonstrate that even when using a laser with a poor spatial profile, there will exist a minimum fiber length that allows transmission of only the Gaussian-like fundamental waveguide mode from the fiber, filtering out all the higher order modes. This essentially single mode output is preserved also when the waveguide is bent to a radius of curvature of 7.5 cm, which demonstrates that laser mode filtering can be realized even if a curved light path is required.

Summary of the guideline on underwater laser beam repair welding

International Nuclear Information System (INIS)

Ichikawa, Hiroya; Yoda, Masaki; Motora, Yuichi

2013-01-01

It is known that stress corrosion cracking (SCC) might occur at the weld of a reactor pressure vessel or core internals. Underwater laser beam clad welding for mitigation of SCC has been already established and the guideline 'Underwater laser beam clad welding' was published. Moreover, the guideline 'Seal welding' was also published as a repair method for SCC. In addition to these guidelines, the guideline 'Underwater laser beam repair welding' was newly published in November, 2012 for the repair welding after completely removing a SCC crack occurred in weld or base metal. This paper introduces the summary of this guideline. (author)

Soft apertures to shape high-power laser beams

International Nuclear Information System (INIS)

Lukishova, S.G.; Pashinin, P.P.; Batygov, S.K.; Terentiev, B.M.

1989-01-01

Soft or apodized apertures with smooth decreasing from center to edges transmission profiles are used in laser physics for beam shaping. This paper gives the results of the studies of four types of these units for UV, visible and IR lasers. They are made of glasses or crystals with the use of one of the following technologies: absorption induced by ionizing radiation; photodestruction of color centers or photooxidation of impurities ions; additive coloration; frustrated total internal reflection. The special feature of such apertures is their high optical damage resistance under the irradiation of single-pulse laser radiation. They are approximately 3-50 mm in diameter by the methods of making them give the possibility to create near-Gaussian and flat-top beams with dimensions less than 1 mm and larger than 200 mm. The results of using them in high-power single-pulse lasers are presented. Damage thresholds of these apertures in such types of lasers have been defined

Closely spaced mirror pair for reshaping and homogenizing pump beams in laser amplifiers

International Nuclear Information System (INIS)

Bass, I.L.

1992-12-01

Channeling a laser beam by multiple reflections between two closely-spaced, parallel or nearly parallel mirrors, serves to reshape and homogenize the beam at the output gap between the mirrors. Application of this device to improve the spatial overlap of a copper laser pump beam with the signal beam in a dye laser amplifier is described. This technique has been applied to the AVLIS program at the Lawrence Livermore National Laboratory

Characterisation of beams of low power infrared lasers for medical uses

International Nuclear Information System (INIS)

Welch, M.; Ramsay, D.

1996-01-01

Full text: The initial aim of this work was to investigate the power stability, both temporally and spatially, of the beams of low power infrared diode lasers of the type used by physiotherapists and vascular surgeons. Most of the lasers in this category are small, handheld devices, often with on/off switches which are manually held on while the laser is running. Two of those tested were larger, on stands, and could be set to run for a nominated time. Measurements made by one of us prior to the project had indicated that the power output of at least one of the lasers in use at Westmead Hospital was varying significantly over the treatment time. It is not at present known whether or not uniformity of power output is a significant factor in low power laser therapy, which has been shown to have beneficial effects for conditions ranging from torn muscles and arthritis to birth marks. Dramatic improvement in the healing of skin ulcers and wounds such as amputation scars has also been recorded. Equipment was chosen and a set of techniques developed for analysing the laser beams (some of which operated in continuous wave mode, some in pulsed mode, and some in both) with respect to: power output over time; power distribution within the beam, ie., beam profile; beam divergence; and pulse repetition frequency and pulse shape, if applicable. The fact that some of the lasers were continuous wave, some were pulsed and that some had very high pulse repetition frequencies placed restrictions on the type of power meter which could be used. Eventually a surface absorbing thermal power meter, responsive over a wide range of wavelengths, was chosen for temporal power measurements. Pulse repetition rates and pulse shapes were shown on a CRO; and spatial power distribution, beam shape, power distribution and divergence were recorded via a CCD camera and Spiricon laser beam analyser. 3D printouts from the Spiricon were made showing distribution of beam power. Nine lasers were analysed

Acceleration of laser-injected electron beams in an electron-beam driven plasma wakefield accelerator

International Nuclear Information System (INIS)

Knetsch, Alexander

2018-03-01

Plasma wakefields deliver accelerating fields that are approximately a 100 times higher than those in conventional radiofrequency or even superconducting radiofrequency cavities. This opens a transformative path towards novel, compact and potentially ubiquitous accelerators. These prospects, and the increasing demand for electron accelerator beamtime for various applications in natural, material and life sciences, motivate the research and development on novel plasma-based accelerator concepts. However, these electron beam sources need to be understood and controlled. The focus of this thesis is on electron beam-driven plasma wakefield acceleration (PWFA) and the controlled injection and acceleration of secondary electron bunches in the accelerating wake fields by means of a short-pulse near-infrared laser. Two laser-triggered injection methods are explored. The first one is the Trojan Horse Injection, which relies on very good alignment and timing control between electron beam and laser pulse and then promises electron bunches with hitherto unprecedented quality as regards emittance and brightness. The physics of electron injection in the Trojan Horse case is explored with a focus on the final longitudinal bunch length. Then a theoretical and numerical study is presented that examines the physics of Trojan Horse injection when performed in an expanding wake generated by a smooth density down-ramp. The benefits are radically decreased drive-electron bunch requirements and a unique bunch-length control that enables longitudinal electron-bunch shaping. The second laser-triggered injection method is the Plasma Torch Injection, which is a versatile, all-optical laser-plasma-based method capable to realize tunable density downramp injection. At the SLAC National Laboratory, the first proof-of-principle was achieved both for Trojan Horse and Plasma Torch injection. Setup details and results are reported in the experimental part of the thesis along with the commissioning

The Brookhaven ATF low-emittance beam line

International Nuclear Information System (INIS)

Wang, X.J.; Kirk, H.G.

1991-01-01

One component of the experimental program at the Brookhaven Accelerator Test Facility (ATF) consists of a class of experiments which will study the acceleration of electrons through micron-size structures which are exposed in coincidence to a 100 GW CO 2 laser beam. These experiments require the development and control of an electron beam with geometric emittances on the order of 10 -10 m-rad and intensities on the order of 10 6 electrons. In this paper, the authors describe the strategies for producing such beams and the effects of higher-order aberrations. Particle tracking results are presented for the final-focus system

Narrow linewidth operation of a spectral beam combined diode laser bar.

Science.gov (United States)

Zhu, Zhanda; Jiang, Menghua; Cheng, Siqi; Hui, Yongling; Lei, Hong; Li, Qiang

2016-04-20

Our experiment is expected to provide an approach for realizing ultranarrow linewidth for a spectral beam combined diode laser bar. The beams of a diode laser bar are combined in a fast axis after a beam transformation system. With the help of relay optics and a transform lens with a long focal length of 1.5 m, the whole wavelength of a spectral combined laser bar can be narrowed down to 0.48 nm from more than 10 nm. We have achieved 56.7 W cw from a 19-element single bar with an M2 of 1.4  (in horizontal direction)×11.6  (in vertical direction). These parameters are good evidence that all the beams from the diode laser bar are combined together to increase the brightness.

Initial Beam Test of the Prototype Strip Line BPM

International Nuclear Information System (INIS)

Kwon, Hyeok Jung; Kim, Han Sung; Seol, Kyung Tae; Ryu, Jin Yeong; Jang, Ji Ho; Cho, Yong Sub

2011-01-01

A beam position monitor (BPM) was developed which would be used for the Proton Engineering Frontier Project (PEFP) beam line. It is a strip line BPM which is commonly used one for the proton beam. The BPM cross section was designed with the SUPERFISH code and the matching section to the feed through was designed by the MWS code. The design parameters of the BPM are shown in Table 1. The designed BPM was fabricated to verify the manufacturing process and check its electrical performance. After the low power test at the test stand, the BPM was installed at the 20-MeV proton accelerator beam line as shown in Fig. 1

Scintillation reduction for laser beams propagating through turbulent atmosphere

International Nuclear Information System (INIS)

Berman, G P; Gorshkov, V N; Torous, S V

2011-01-01

We numerically examine the spatial evolution of the structure of coherent and partially coherent laser beams, including the optical vortices, propagating in turbulent atmospheres. The influence of beam fragmentation and wandering relative to the axis of propagation (z-axis) on the value of the scintillation index (SI) of the signal at the detector is analysed. These studies were performed for different dimensions of the detector, distances of propagation, and strengths of the atmospheric turbulence. Methods for significantly reducing the SI are described. These methods utilize averaging of the signal at the detector over a set of partially coherent beams (PCBs). It is demonstrated that the most effective approach is using a set of PCBs with definite initial directions of propagation relative to the z-axis. This approach results in a significant compensation of the beam wandering which in many cases is the main contributor to the SI. A novel method is to generate the PCBs by combining two laser beams-Gaussian and vortex beams, with different frequencies (the difference between these two frequencies being significantly smaller than the frequencies themselves). In this case, the effective suppression of the SI does not require high-frequency modulators. This result is important for achieving gigabit data rates in long-distance laser communication through turbulent atmospheres.

Scintillation reduction for laser beams propagating through turbulent atmosphere

Energy Technology Data Exchange (ETDEWEB)

Berman, G P; Gorshkov, V N [Theoretical Division, T-4 and CNLS MS B213, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Torous, S V, E-mail: gpb@lanl.gov [National Technical University of Ukraine ' KPI' , 37 Peremogy Avenue, Building 7, Kiev-56, 03056 (Ukraine)

2011-03-14

We numerically examine the spatial evolution of the structure of coherent and partially coherent laser beams, including the optical vortices, propagating in turbulent atmospheres. The influence of beam fragmentation and wandering relative to the axis of propagation (z-axis) on the value of the scintillation index (SI) of the signal at the detector is analysed. These studies were performed for different dimensions of the detector, distances of propagation, and strengths of the atmospheric turbulence. Methods for significantly reducing the SI are described. These methods utilize averaging of the signal at the detector over a set of partially coherent beams (PCBs). It is demonstrated that the most effective approach is using a set of PCBs with definite initial directions of propagation relative to the z-axis. This approach results in a significant compensation of the beam wandering which in many cases is the main contributor to the SI. A novel method is to generate the PCBs by combining two laser beams-Gaussian and vortex beams, with different frequencies (the difference between these two frequencies being significantly smaller than the frequencies themselves). In this case, the effective suppression of the SI does not require high-frequency modulators. This result is important for achieving gigabit data rates in long-distance laser communication through turbulent atmospheres.

Zeeman structure of red lines of lanthanum observed by laser spectroscopy methods

Science.gov (United States)

Sobolewski, Ł. M.; Windholz, L.; Kwela, J.

2017-11-01

Laser Induced Fluorescence (LIF) Spectroscopy and Optogalvanic (OG) Spectroscopy were used for the investigation of the Zeeman hyperfine (hf) structures of 27 spectral lines of La I in the wavelength range between 633.86 and 667.54 nm. As a source of free La atoms a hollow cathode discharge lamp was used. Spectra were recorded in the presence of a relatively weak magnetic field (about 800G) produced by a permanent magnet, for two linear polarization directions of the exciting laser beam. As a result of the measurements, we determined for the first time the Landé gJ- factors of 18 levels of La I. The Landé gJ- factors of 12 other levels were re-investigated and determined with higher accuracy.

Spatial beam shaping using a micro-structured optical fiber and all-fiber laser amplification system for large-scale laser facilities seeding

International Nuclear Information System (INIS)

Calvet, Pierre

2014-01-01

Spatial beam shaping is an important topic for the lasers applications. For various industrial areas (marking, drilling, laser-matter interaction, high-power laser seeding...) the optical beam has to be flattened. Currently, the state of the art of the beam shaping: 'free-space' solutions or highly multimode fibers, are not fully suitable. The first ones are very sensitive to any perturbations and the maintenance is challenging, the second ones cannot deliver a coherent beam. For this reason, we present in this manuscript a micro-structured optical single-mode fiber delivering a spatially flattened beam. This 'Top-Hat' fiber can shape any beam in a spatially coherent beam what is a progress with respect to the highly multimode fibers used in the state of the art. The optical fibers are easy to use and very robust, what is a strong benefit with respect to the 'free-space' solutions. Thanks to this fiber, we could realize an all-fiber multi-stage laser chain to amplify a 10 ns pulse to 100 μJ. Moreover the temporal, spectral and spatial properties were preserved. We adapted this 'Top-Hat' fiber to this multi-stage laser chain, we proved the capability and the interest of this fiber for the spatial beam shaping of the laser beams in highly performing and robust laser systems. (author) [fr

Studies on the beam system for the calibration of the OPAL jet chamber with laser beams

International Nuclear Information System (INIS)

Maringer, G.

1988-07-01

UV laser beams are an important tool for the calibration of the OPAL jet chamber. A beam transport system containing about 350 mirrors in total guides the beams from the laser outside the detector into the chamber. Four of the mirrors are moveable under remote control allowing to guide the beams into each of the 24 sectors and to correct the beam path in case of deviations. A program to control these moveable mirrors has been developed. Drift velocity measurements will be performed by means of double beams which are generated by appropriate beamsplitters. Accurate knowledge of the double beam distances is essential to obtain the desired accuracy of better than 0.1% or 10 μm. Using a CCD device with a pixel size of 23x23 μm 2 the beam distance could be measured with errors below the required limit. (orig.)

2000W high beam quality diode laser for direct materials processing

Science.gov (United States)

Qin, Wen-bin; Liu, You-qiang; Cao, Yin-hua; Gao, Jing; Pan, Fei; Wang, Zhi-yong

2011-11-01

This article describes high beam quality and kilowatt-class diode laser system for direct materials processing, using optical design software ZEMAX® to simulate the diode laser optical path, including the beam shaping, collimation, coupling, focus, etc.. In the experiment, the diode laser stack of 808nm and the diode laser stack of 915nm were used for the wavelength coupling, which were built vertical stacks up to 16 bars. The threshold current of the stack is 6.4A, the operating current is 85A and the output power is 1280W. Through experiments, after collimating the diode laser beam with micro-lenses, the fast axis BPP of the stack is less than 60mm.mrad, and the slow-axis BPP of the stack is less than 75mm.mrad. After shaping the laser beam and improving the beam quality, the fast axis BPP of the stack is still 60mm.mrad, and the slow-axis BPP of the stack is less than 19mm.mrad. After wavelength coupling and focusing, ultimately the power of 2150W was obtained, focal spot size of 1.5mm * 1.2mm with focal length 300mm. The laser power density is 1.2×105W/cm2, and that can be used for metal remelting, alloying, cladding and welding. The total optical coupling conversion efficiency is 84%, and the total electrical - optical conversion efficiency is 50%.

Evaluating the beam quality of double-cladding fiber lasers in applications.

Science.gov (United States)

Yan, Ping; Wang, Xuejiao; Gong, Mali; Xiao, Qirong

2016-08-10

We put forward a new βFL factor, which is used exclusively in fiber lasers and is suitable to assess beam quality and choose the LP01 mode as the new suitable ideal beam. We present a new simple measurement method and verify the reasonability of the βFL factor in experiment in a 20/400 μm fiber laser. Furthermore, we use the βFL factor to evaluate the beam quality of a 3-kW-level fiber laser. It can be concluded that βFL is a key factor not only for assessing the performance of the high-power fiber laser that is our main focus, but also for the simple measurement.

Propagation of a laser beam in a time-varying waveguide

International Nuclear Information System (INIS)

Chapman, J.M.; Kevorkian, J.

1978-01-01

The propagation of an axisymmetric laser beam in a plasma column having a radially parabolic electron density distribution is examined. First, an extended paraxial procedure is developed for the case of an axially uniform waveguide. It is shown that the essential feature of an alternate focusing and defocusing beam is retained, but that the intensity distribution is cumulatively modified at the foci and at the outer portions of the beam as compared to that of the paraxial case. Second, some general features of paraxial beam propagation are examined for the case of axially varying waveguides. Finally, laser plasma coupling is examined for the case when laser heating generates a density distribution that is radially parabolic near the axis and when the energy absorbed over a focal length of a plasma lens is small. It is shown that stable or unstable beam propagation depends upon the relative magnitude of the density fluctuations which exist in the axial variation of the waveguides as a result of laser heating. When the fluctuations are small, the propagation is stable, and a simple algebraic expression is obtained which relates the beam diameter to the axially slow averaged variation in the waveguide. When the fluctuations are large, the propagation stability can be determined only by consistently combining plasma dynamics and beam propagation to interrelate the axial variation of the beam to that of the waveguide. In this case of beam propagation in a time-varying waveguide, it is shown that the global stability of the propagation depends upon the initial fluctuation growth rate compared to the initial time rate of change in the radial curvature of the waveguide

Interaction of a CO2 laser beam with a shock-tube plasma

International Nuclear Information System (INIS)

Box, S.J.C.; John, P.K.; Byszewski, W.W.

1977-01-01

The results of experimental investigations of the interaction of a CO 2 laser beam with plasma produced in an electromagnetic shock tube are presented. The interaction was investigated in two different configurations: with the laser beam perpendicular to the direction of propagation of the shock wave and with the laser beam parallel to the direction of the shock wave. The laser energy was 0.3 J in a 180-nsec pulse. The plasma density was in the range 10 17 --10 18 cm -3 and temperature was around 2 eV. Spectroscopic methods were used in the measurement of density and temperature. Direct observation of the path of the laser beam through the plasma was made by an image-convertor camera in conjunction with a narrow-band interference filter. The propagation of the laser through the plasma and energy absorption are discussed. The observed maximum increase in electron temperature due to the laser in the first configuration was 0.4 eV and the estimated temperature increase in the second configuration was about 2 eV

Laser-Bioplasma Interaction: The Blood Type Transmutation Induced by Multiple Ultrashort Wavelength Laser Beams

Science.gov (United States)

Stefan, V. Alexander

2015-11-01

The interaction of ultrashort wavelength multi laser beams with the flowing blood thin films leads to the transmutation of the blood types A, B, and AB into O type. This is a novel mechanism of importance for the transfusion medicine. Laser radiation is in resonance with the eigen-frequency modes of the antigen proteins and forces the proteins to parametrically oscillate until they get kicked out from the surface. The stripping away of antigens is done by the scanning-multiple-lasers of a high repetition rate in the blue-purple frequency domain. The guiding-lasers are in the red-green frequency domain. The laser force, (parametric interaction with the antigen eigen-oscillation), upon the antigen protein molecule must exceed its weight. The scanning laser beam is partially reflected as long as the antigen(s) is not eliminated. The process of the protein detachment can last a few minutes. Supported by Nikola Tesla Labs., Stefan University.