A Cherenkov radiator for FEL-synchronized VUV-pulses at a linac-based FEL

NARCIS (Netherlands)

Goloviznin, V.V.; Oepts, W.; Wiel, van der M.J.

1997-01-01

A possible way to carry out two-color IR + VUV pump-probe experiments at linac-based FELs is proposed. The idea is to supply an FEL facility with a gas cell filled with helium or hydrogen, so that the electron beam, upon passage through the undulator, could be used to generate ultraviolet Cherenkov

Producing High Intense Attosecond Pulse Train by Interaction of Three-Color Pulse and Overdense Plasma

Science.gov (United States)

Salehi, M.; Mirzanejad, S.

2017-05-01

Amplifying the attosecond pulse by the chirp pulse amplification method is impossible. Furthermore, the intensity of attosecond pulse is low in the interaction of laser pulse and underdense plasma. This motivates us to propose using a multi-color pulse to produce the high intense attosecond pulse. In the present study, the relativistic interaction of a three-color linearly-polarized laser-pulse with highly overdense plasma is studied. We show that the combination of {{ω }}1, {{ω }}2 and {{ω }}3 frequencies decreases the instance full width at half maximum reflected attosecond pulse train from the overdense plasma surface. Moreover, we show that the three-color pulse increases the intensity of generated harmonics, which is explained by the relativistic oscillating mirror model. The obtained results demonstrate that if the three-color laser pulse interacts with overdense plasma, it will enhance two orders of magnitude of intensity of ultra short attosecond pulses in comparison with monochromatic pulse.

Low-intensity pulsed ultrasound: Nonunions

Directory of Open Access Journals (Sweden)

Dijkman Bernadette

2009-01-01

Full Text Available Nonunions occur in 5-10% of fractures and are characterized by the failure to heal without further intervention. Low intensity pulsed ultrasound therapy has been developed as an alternative to surgery in the treatment of nonunions. We describe a systematic review on trials of low-intensity pulsed ultrasound therapy for healing of nonunions. We searched the electronic databases Medline and the Cochrane library for articles on ultrasound and healing of nonunions published up to 2008. Trials selected for the review met the following criteria: treatment of at least one intervention group with low intensity pulsed ultrasound; inclusion of patients (humans with one or more nonunions (defined as "established" or as a failure to heal for a minimum of eight months after initial injury; and assessment of healing and time to healing, as determined radiographically. The following data were abstracted from the included studies: sample size, ultrasound treatment characteristics, nonunion location, healing rate, time to fracture healing, fracture age, and demographic information. We found 79 potentially eligible publications, of which 14 met our inclusion criteria. Of these, eight studies were used for data abstraction. Healing rates averaged 87%, (range 65.6%-100% among eight trials. Mean time to healing was 146.5 days, (range 56-219 days. There is evidence from trials that low-intensity pulsed ultrasound may be an effective treatment for healing of nonunions. More homogeneous and larger controlled series are needed to further investigate its efficacy.

Bipolar pulse generator for intense pulsed ion beam accelerator

International Nuclear Information System (INIS)

Ito, H.; Igawa, K.; Kitamura, I.; Masugata, K.

2007-01-01

A new type of pulsed ion beam accelerator named ''bipolar pulse accelerator'' (BPA) has been proposed in order to improve the purity of intense pulsed ion beams. To confirm the principle of the BPA, we developed a bipolar pulse generator for the bipolar pulse experiment, which consists of a Marx generator and a pulse forming line (PFL) with a rail gap switch on its end. In this article, we report the first experimental result of the bipolar pulse and evaluate the electrical characteristics of the bipolar pulse generator. When the bipolar pulse generator was operated at 70% of the full charge condition of the PFL, the bipolar pulse with the first (-138 kV, 72 ns) and the second pulse (+130 kV, 70 ns) was successfully obtained. The evaluation of the electrical characteristics indicates that the developed generator can produce the bipolar pulse with fast rise time and sharp reversing time

VUV spectroscopy in impurity injection experiments at KSTAR using prototype ITER VUV spectrometer

Science.gov (United States)

Seon, C. R.; Hong, J. H.; Song, I.; Jang, J.; Lee, H. Y.; An, Y. H.; Kim, B. S.; Jeon, T. M.; Park, J. S.; Choe, W.; Lee, H. G.; Pak, S.; Cheon, M. S.; Choi, J. H.; Kim, H. S.; Biel, W.; Bernascolle, P.; Barnsley, R.

2017-08-01

The ITER vacuum ultra-violet (VUV) core survey spectrometer has been designed as a 5-channel spectral system so that the high spectral resolving power of 200-500 could be achieved in the wavelength range of 2.4-160 nm. To verify the design of the ITER VUV core survey spectrometer, a two-channel prototype spectrometer was developed. As a subsequent step of the prototype test, the prototype VUV spectrometer has been operated at KSTAR since the 2012 experimental campaign. From impurity injection experiments in the years 2015 and 2016, strong emission lines, such as Kr xxv 15.8 nm, Kr xxvi 17.9 nm, Ne vii 46.5 nm, Ne vi 40.2 nm, and an array of largely unresolved tungsten lines (14-32 nm) could be measured successfully, showing the typical photon number of 1013-1015 photons/cm2 s.

Electron acceleration by a self-diverging intense laser pulse

International Nuclear Information System (INIS)

Singh, K.P.; Gupta, D.N.; Tripathi, V.K.; Gupta, V.L.

2004-01-01

Electron acceleration by a laser pulse having a Gaussian radial and temporal profile of intensity has been studied. The interaction region is vacuum followed by a gas. The starting point of the gas region has been chosen around the point at which the peak of the pulse interacts with the electron. The tunnel ionization of the gas causes a defocusing of the laser pulse and the electron experiences the action of a ponderomotive deceleration at the trailing part of the pulse with a lower intensity rather than an acceleration at the rising part of the laser pulse with a high intensity, and thus gains net energy. The initial density of the neutral gas atoms should be high enough to properly defocus the pulse; otherwise the electron experiences some deceleration during the trailing part of the pulse and the net energy gain is reduced. The rate of tunnel ionization increases with the increase in the laser intensity and the initial density of neutral gas atoms, and with the decreases in the laser spot size, which causes more defocusing of the laser pulse. The required initial density of neutral gas atoms decreases with the increase in the laser intensity and also with the decrease in the laser spot size

Intense pulsed ion beams for fusion applications

International Nuclear Information System (INIS)

Humphries, S. Jr.

1980-04-01

The subject of this review paper is the field of intense pulsed ion beam generation and the potential application of the beams to fusion research. Considerable progress has been made over the past six years. The ion injectors discussed utilize the introduction of electrons into vacuum acceleration gaps in conjunction with high voltage pulsed power technology to achieve high output current. Power levels from injectors exceeding 1000 MW/cm 2 have been obtained for pulse lengths on the order of 10 -7 sec. The first part of the paper treats the physics and technology of intense ion beams. The second part is devoted to applications of intense ion beams in fusion research. A number of potential uses in magnetic confinement systems have been proposed

Generation of an intense pulsed positron beam and its applications

International Nuclear Information System (INIS)

Suzuki, Ryoichi; Mikado, Tomohisa; Ohgaki, Hideaki; Chiwaki, Mitsukuni; Yamazaki, Tetsuo; Kobayashi, Yoshinori.

1994-01-01

A positron pulsing system for an intense positron beam generated by an electron linac has been developed at the Electrotechnical Laboratory. The pulsing system generates an intense pulsed positron beam of variable energy and variable pulse period. The pulsed positron beam is used as a non destructive probe for various materials researches. In this paper, we report the present status of the pulsed positron beam and its applications. (author)

Three-dimensional laser pulse intensity diagnostic for photoinjectors

Directory of Open Access Journals (Sweden)

Heng Li

2011-11-01

Full Text Available Minimizing the electron-beam emittance of photoinjectors is an important task for maximizing the brightness of the next-generation x-ray facilities, such as free-electron lasers and energy recovery linacs. Optimally shaped laser pulses can significantly reduce emittance. A reliable diagnostic for the laser pulse intensity is required for this purpose. We demonstrate measurement of three-dimensional spatiotemporal intensity profiles, with spatial resolution of 20  μm and temporal resolution of 130 fs. The capability is illustrated by measurements of stacked soliton pulses and pulses from a dissipative-soliton laser.

Pulsed system for obtaining microdosimetric data with high intensity beams

International Nuclear Information System (INIS)

Zaider, M.; Dicello, J.F.; Hiebert, R.D.

1977-01-01

The use of heavy particle accelerators for radiation therapy requires high intensity beams in order to produce useful dose rates. The 800-MeV proton beam at LAMPF passes through different production targets to generate secondary pion beams. Conventional microdosimetric techniques are not applicable under these conditions because exceedingly high count rates result in detector damage, gas breakdown, and saturation effects in the electronics. We describe a new microdosimetric system developed at the Pion Biomedical Channel of LAMPF. The accelerator provides a variable low intensity pulse once every ten high intensity macropulses. The voltage on the detector is pulsed in coincidence with the low intensity pulse so that we were able to operate the detector under optimum data-taking conditions. A low noise two-stage preamplifier was built in connection with the pulsed mode operation. A comparison is made between data obtained in pulsed (high intensity beam) and unpulsed (low intensity beam) modes. The spectra obtained by the two methods agree within the experimental uncertainties

Simultaneous removal of NO and SO2 using vacuum ultraviolet light (VUV)/heat/peroxymonosulfate (PMS).

Science.gov (United States)

Liu, Yangxian; Wang, Yan; Wang, Qian; Pan, Jianfeng; Zhang, Jun

2018-01-01

Simultaneous removal process of SO 2 and NO from flue gas using vacuum ultraviolet light (VUV)/heat/peroxymonosulfate (PMS) in a VUV spraying reactor was proposed. The key influencing factors, active species, reaction products and mechanism of SO 2 and NO simultaneous removal were investigated. The results show that vacuum ultraviolet light (185 nm) achieves the highest NO removal efficiency and yield of and under the same test conditions. NO removal is enhanced at higher PMS concentration, light intensity and oxygen concentration, and is inhibited at higher NO concentration, SO 2 concentration and solution pH. Solution temperature has a double impact on NO removal. CO 2 concentration has no obvious effect on NO removal. and produced from VUV-activation of PMS play a leading role in NO removal. O 3 and ·O produced from VUV-activation of O 2 also play an important role in NO removal. SO 2 achieves complete removal under all experimental conditions due to its very high solubility in water and good reactivity. The highest simultaneous removal efficiency of SO 2 and NO reaches 100% and 91.3%, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Recent development of VUV-based processes for air pollutants degradation

Directory of Open Access Journals (Sweden)

Haibao eHuang

2016-03-01

Full Text Available As air pollution become more and more serious nowadays, it is essential to find out a way to efficiently degrade the air pollutants. Vacuum ultraviolet (VUV-based processes are an emerging and promising technologies for environmental remediation such as air cleaning, wastewater treatment and air/water disinfection. With VUV irradiation, photolysis, photocatalyst is and ozone-assisted oxidation are involved at the same time, resulting in the fast degradation of air pollutants because of their strong oxidizing capacity. The mechanisms of how the oxidants are produced and reacted are discussed in this review. This paper mainly focuses on the three VUV-based oxidation processes including VUV photolysis, VUV combined with ozone-assisted oxidation and VUV-PCO with emphasis on their mechanisms and applications. Also, the outlooks of these processes are outlined in this paper.

UV and VUV characteristics of (YGd)2O3:Eu phosphor particles prepared by spray pyrolysis from polymeric precursors

International Nuclear Information System (INIS)

Kim, E.J.; Kang, Y.C.; Park, H.D.; Ryu, S.K.

2003-01-01

Red-emitting (YGd) 2 O 3 :Eu phosphor particles, with high luminescence efficiency under vacuum ultraviolet (VUV) and ultraviolet (UV) excitation, were prepared by a large-scale spray pyrolysis process. To control the morphology of phosphor particles under severe preparation conditions, spray solution with polymeric precursors were introduced in spray pyrolysis. The prepared (YGd) 2 O 3 :Eu phosphor particles had spherical shape and filled morphology even after post-treatment irrespective of Gd/Y ratio. In the case of solution with polymeric precursors, long polymeric chains formed by esterification reaction in a hot tubular reactor; the droplets turned into viscous gel, which retarded the precipitation of nitrate salts and promoted the volume precipitation of droplets. The brightness of (YGd) 2 O 3 :Eu phosphor particles increased with increasing gadolinium content, and the Gd 2 O 3 :Eu phosphor had the highest luminescence intensity under UV and VUV excitation. The maximum peak intensity of Gd 2 O 3 :Eu phosphor particles under UV and VUV were 118 and 110% of the commercial Y 2 O 3 :Eu phosphor particles, respectively

Probing colliding Calcium plasmas with emission and VUV absorption imaging

International Nuclear Information System (INIS)

Kavanagh, K.D.; Hirsch, J.S.; Kennedy, E.T.; Costello, T.; Poletto, L.; Nicolosi, P.

2004-01-01

Full text: Laser produced plasmas are formed when a short pulse and high power laser is focused onto a surface. Applications range from VUV/X-ray sources for lithography, microscopy and radiography to X-ray lasers, thin film deposition, analytical spectroscopy and electron/ion beam generation (and even acceleration). A battery of particle and optical techniques are now used to diagnose laser plasmas. One highly successful technique is gated-CCD (Charged Coupled Device) imaging of plasma plumes. It provides critical data on the early (creation) and late (expansion) phases of plasma plumes. However, this technique is limited to detecting only the excited (emitting) species in the plume. Recently, we developed a vacuum-UV (VUV) photoabsorption imaging facility called VPIF which enables one can track the evolution of dark plume matter or non-emitting plasma species residing in ground and metastable states. Although much is known about the dynamics of single laser plasma plumes expanding freely, little is known about the overlap between colliding plasma plumes. We are currently performing combined conventional gated CCD imaging and spectroscopy with VUV absorption imaging to map the evolution of the overlap volume of two colliding and interpenetrating plasma plumes. We are specifically tracking ground state singly ionized calcium in the plasmas by tuning into the inner shell 3p to 3d transition at 33.2 eV while the excited state species are tracked using transitions in the UV -NIR spectral range. The experiment may be cast as a model system for atmospheric and/or astrophysical colliding systems, e.g., when tracer elements are injected into supersonic winds at high altitude or when supernovae eject plasma into the solar wind

Relaxation and excitation electronic processes in dielectrics irradiated by ultrafast IR and VUV pulses; Processus electroniques d'excitation et de relaxation dans les solides dielectriques excites par des impulsions IR et XUV ultracourtes

Energy Technology Data Exchange (ETDEWEB)

Gaudin, J

2005-11-15

We studied excitation and relaxation of electrons involved during interaction of visible and VUV femtosecond pulses with dielectrics. The generated population of hot electrons, having energy of few eV to few tens of eV above the bottom of the conduction band, is responsible of phenomena ranging to defect creation to optical breakdown. Owing to two techniques: photoemission and transient photoconductivity we improve the understanding of the The first photoemission experiments deal with dielectrics irradiated by 30 fs IR pulses. The photoemission spectra measured show a large population of electrons which energy rise up to 40 eV. We interpret this result in terms of a new absorption process: direct multi-photons inter-branch transitions. The 2. type of photoemission experiments are time resolved 'pump/probe' investigation. We study the relaxation of electrons excited by a VUV pulses. We used the high order harmonics (HOH) as light sources. We found surprisingly long decay time in the range of ps timescale. Last type of experiments is photoconductivity studies of diamond samples. Using HOH as light source we measure the displacement current induced by excited electrons in the conduction band. Those electrons relax mainly by impact ionisation creating secondary electrons. Hence by probing the number of electrons we were able to measure the efficiency of these relaxation processes. We observe a diminution of this efficiency when the energy of exciting photons is above 20 eV. Owing to Monte-Carlo simulation we interpret this result in terms of band structure effect. (author)

Research and simulation of intense pulsed beam transfer in electrostatic accelerate tube

International Nuclear Information System (INIS)

Li Chaolong; Shi Haiquan; Lu Jianqin

2012-01-01

To study intense pulsed beam transfer in electrostatic accelerate tube, the matrix method was applied to analyze the transport matrixes in electrostatic accelerate tube of non-intense pulsed beam and intense pulsed beam, and a computer code was written for the intense pulsed beam transporting in electrostatic accelerate tube. Optimization techniques were used to attain the given optical conditions and iteration procedures were adopted to compute intense pulsed beam for obtaining self-consistent solutions in this computer code. The calculations were carried out by using ACCT, TRACE-3D and TRANSPORT for different beam currents, respectively. The simulation results show that improvement of the accelerating voltage ratio can enhance focusing power of electrostatic accelerate tube, reduce beam loss and increase the transferring efficiency. (authors)

Muonic molecular ions p p μ and p d μ driven by superintense VUV laser pulses: Postexcitation muonic and nuclear oscillations and high-order harmonic generation

Science.gov (United States)

Paramonov, Guennaddi K.; Saalfrank, Peter

2018-05-01

The non-Born-Oppenheimer quantum dynamics of p p μ and p d μ molecular ions excited by ultrashort, superintense VUV laser pulses polarized along the molecular axis (z ) is studied by the numerical solution of the time-dependent Schrödinger equation within a three-dimensional (3D) model, including the internuclear distance R and muon coordinates z and ρ , a transversal degree of freedom. It is shown that in both p p μ and p d μ , muons approximately follow the applied laser field out of phase. After the end of the laser pulse, expectation values , , and demonstrate "post-laser-pulse" oscillations in both p p μ and p d μ . In the case of p d μ , the post-laser-pulse oscillations of and appear as shaped "echo pulses." Power spectra, which are related to high-order harmonic generation (HHG), generated due to muonic and nuclear motion are calculated in the acceleration form. For p d μ it is found that there exists a unique characteristic frequency ωoscp d μ representing both frequencies of post-laser-pulse muonic oscillations and the frequency of nuclear vibrations, which manifest themselves by very sharp maxima in the corresponding power spectra of p d μ . The homonuclear p p μ ion does not possess such a unique characteristic frequency. The "exact" dynamics and power, and HHG spectra of the 3D model are compared with a Born-Oppenheimer, fixed-nuclei model featuring interesting differences: postpulse oscillations are absent and HHG spectra are affected indirectly or directly by nuclear motion.

Moderate and high intensity pulsed electric fields

OpenAIRE

Timmermans, Rian Adriana Hendrika

2018-01-01

Pulsed Electric Field (PEF) processing has gained a lot of interest the last decades as mild processing technology as alternative to thermal pasteurisation, and is suitable for preservation of liquid food products such as fruit juices. PEF conditions typically applied at industrial scale for pasteurisation are high intensity pulsed electric fields aiming for minimal heat load, with an electric field strength (E) in the range of 15 − 20 kV/cm and pulse width (τ) between 2 − 20 μs. Alternativel...

Hydrothermal synthesis and luminescent properties of LnPO4:Tb,Bi (Ln=La,Gd) phosphors under UV/VUV excitation

International Nuclear Information System (INIS)

Wang Yuhua; Wu Chunfang; Wei Jie

2007-01-01

Monoclinic LnPO 4 :Tb,Bi (Ln=La,Gd) phosphors were prepared by hydrothermal reaction and their luminescent properties under ultraviolet (UV) and vacuum ultraviolet (VUV) excitation were investigated. LaPO 4 :Tb,Bi phosphor and GdPO 4 :Tb phosphor showed the strongest emission intensity under 254 and 147 nm excitation, respectively, because of the different energy transfer models. In UV region, Bi 3+ absorbed most energy then transferred to Tb 3+ , but in VUV region it was the host which absorbed most energy and transferred to Tb 3+

Development of bipolar pulse accelerator for intense pulsed ion beam acceleration

International Nuclear Information System (INIS)

Fujioka, Y.; Mitsui, C.; Kitamura, I.; Takahashi, T.; Masugata, K.; Tanoue, H.; Arai, K.

2003-01-01

To improve the purity of an intense pulsed ion beams a new type of pulsed ion beam accelerator named 'bipolar pulse accelerator (BPA)' was proposed. In the accelerator purity of the beam is expected. To confirm the principle of the accelerator experimental system was developed. The system utilizes B y type magnetically insulated acceleration gap and operated with single polar negative pulse. A coaxial gas puff plasma gun placed in the grounded anode was used as an ion source, and source plasma (nitrogen) of current density approx. = 25 A/cm 2 , duration approx. = 1.5 μs was injected into the acceleration gap. The ions are successfully accelerated from the grounded anode to the drift tube by applying negative pulse of voltage 180 kV, duration 60 ns to the drift tube. Pulsed ion beam of current density approx. = 40 A/cm 2 , duration approx. 60 ns was obtained at 42 mm downstream from the anode surface. (author)

Digital low level RF control system for the DESY TTF VUV-FEL Linac

International Nuclear Information System (INIS)

Ayvazyan, V.; Choroba, S.; Matyushin, A.; Moeller, G.; Petrosyan, G.; Rehlich, K.; Simrock, S.N.; Vetrov, P.

2005-01-01

In the RF system for the Vacuum Ultraviolet Free Electron Laser (VUV-FEL) Linac each klystron supplies RF power to up to 32 cavities. The superconducting cavities are operated in pulsed mode and high accelerating gradients close to the performance limit. The RF control of the cavity fields to the level of 10 -4 for amplitude and 0.1 degree for phase however presents a significant technical challenge due to the narrow bandwidth of the cavities which results in high sensitivity to perturbations of the resonance frequency by mechanical vibrations (microphonics) and Lorenz force detuning. The VUV-FEL Linac RF control system employs a completely digital feedback system to provide flexibility in the control algorithms, precise calibration of the accelerating field vector-sum, and extensive diagnostics and exception handling capabilities. The RF control algorithm is implemented in DSP (Digital Signal Processor) firmware and DOOCS (Distributed Object Oriented Control System) servers. The RF control system design objectives are discussed. Hardware and software design of the DSP based RF control are presented. (orig.)

Digital low level RF control system for the DESY TTF VUV-FEL Linac

Energy Technology Data Exchange (ETDEWEB)

Ayvazyan, V.; Choroba, S.; Matyushin, A.; Moeller, G.; Petrosyan, G.; Rehlich, K.; Simrock, S.N.; Vetrov, P.

2005-07-01

In the RF system for the Vacuum Ultraviolet Free Electron Laser (VUV-FEL) Linac each klystron supplies RF power to up to 32 cavities. The superconducting cavities are operated in pulsed mode and high accelerating gradients close to the performance limit. The RF control of the cavity fields to the level of 10{sup -4} for amplitude and 0.1 degree for phase however presents a significant technical challenge due to the narrow bandwidth of the cavities which results in high sensitivity to perturbations of the resonance frequency by mechanical vibrations (microphonics) and Lorenz force detuning. The VUV-FEL Linac RF control system employs a completely digital feedback system to provide flexibility in the control algorithms, precise calibration of the accelerating field vector-sum, and extensive diagnostics and exception handling capabilities. The RF control algorithm is implemented in DSP (Digital Signal Processor) firmware and DOOCS (Distributed Object Oriented Control System) servers. The RF control system design objectives are discussed. Hardware and software design of the DSP based RF control are presented. (orig.)

Pulsed Power Applications in High Intensity Proton Rings

CERN Document Server

Zhang, Wu; Ducimetière, Laurent; Fowler, Tony; Kawakubo, Tadamichi; Mertens, Volker; Sandberg, Jon; Shirakabe, Yoshihisa

2005-01-01

The pulsed power technology has been applied in particle accelerators and storage rings for over four decades. It is most commonly used in injection, extraction, beam manipulation, source, and focusing systems. These systems belong to the class of repetitive pulsed power. In this presentation, we review and discuss the history, present status, and future challenge of pulsed power applications in high intensity proton accelerators and storage rings.

Interaction of intense femtosecond laser pulses with high-Z solids

International Nuclear Information System (INIS)

Zhidkov, A.; Sasaki, Akira; Utsumi, Takayuki; Fukumoto, Ichirou; Tajima, Toshiki; Yoshida, Masatake; Kondo, Kenichi

2000-01-01

A plasma irradiated by an intense very short pulse laser can be an ultimate high brightness source of incoherent inner-shell X-ray emission of 1-30 keV. The recently developed 100 TW, 20 fs laser facility in JAERI can make considerable enhancement here. To show this a hybrid model combining hydrodynamics and collisional particle-in-cell simulations is applied. Effect of laser prepulse on the interaction of an intense s-polarized femtosecond, ∼20/40 fs, laser pulse with high-Z solid targets is studied. A new absorption mechanism originating from the interaction of the laser pulse with plasma waves excited by the relativistic component of the Lorentz force is found to increase the absorption rate over 30% even for a very short laser pulse. The obtained hot electron temperature exceeds 0.5-1 MeV at optimal conditions for absorption. Results of the simulation for lower laser pulse intensities are in good agreement with the experimental measurements of the hot electron energy distribution. (author)

Higher order harmonic generation in the intense laser pulse

International Nuclear Information System (INIS)

Parvizi, R.; Bahrampour, A.; Karimi, M.

2006-01-01

The high intensity pulse of laser field ionizes the atoms and electrons are going to the continuum states of atoms. electrons absorb energy from the strong laser field. The back ground electromagnetic field causes to come back the electrons to ground states of atoms and the absorbed energy is emitted as a high order odd harmonics of incident light. The intensity of emitted harmonics depends on the material atoms and the laser pulse shape. I this paper the effects of step pulse duration on the high order harmonic radiated by the Argon, Helium, and Hydrogen atoms are reported.

Measurement of high-power microwave pulse under intense ...

Indian Academy of Sciences (India)

Abstract. KALI-1000 pulse power system has been used to generate single pulse nanosecond duration high-power microwaves (HPM) from a virtual cathode oscillator. (VIRCATOR) device. HPM power measurements were carried out using a transmitting– receiving system in the presence of intense high frequency (a few ...

Combustion synthesis and optical properties of Oxy-borate phosphors YCa4O(BO3)3:RE3+ (RE = Eu3+, Tb3+) under UV, VUV excitation

International Nuclear Information System (INIS)

Ingle, J.T.; Gawande, A.B.; Sonekar, R.P.; Omanwar, S.K.; Wang, Yuhua; Zhao, Lei

2014-01-01

Graphical abstract: VUV Photoluminescence of YCa 4 O(BO 3 ) 3 : Eu 3+ and YCa 4 O(BO 3 ) 3 : Tb 3+ for PDPs applications. Highlights: • Inorganic Oxy-borate phosphors YCa 4 O(BO 3 ) 3 :Eu 3+ ,Tb 3+ was synthesized by novel solution combustion synthesis. • This single host produces efficient and intense Red and Green color for display applications. • Good agreement with CIE co-ordinates as prescribes by NTCL, for flat panel, PDP display color. • Synthesized materials were characterized using powder XRD, FE-SEM, UV and VUV Spectophotometer. -- Abstract: The inorganic Oxy-borate host phosphors YCa 4 O(BO 3 ) 3 :RE 3+ (RE = Eu 3+ ,Tb 3+ ) were synthesized by a novel solution combustion technique. The synthesis is based on the exothermic reaction between the fuel (Urea) and Oxidizer (Ammonium nitrate). The heat generated in reaction is use for auto combustion of precursors. The structures of the prepared samples were confirmed by powder XRD technique. The photoluminescence properties of the powder samples were investigated under UV and VUV excitation; “The phosphor YCa 4 O(BO 3 ) 3 :Eu 3+ and YCa 4 O(BO 3 ) 3 :Tb 3+ shows strong absorption in UV and VUV region and exhibits intense red and green emission upon excited by 254 nm UV and 147 nm VUV radiation”

Generation of Ultra-high Intensity Laser Pulses

International Nuclear Information System (INIS)

Fisch, N.J.; Malkin, V.M.

2003-01-01

Mainly due to the method of chirped pulse amplification, laser intensities have grown remarkably during recent years. However, the attaining of very much higher powers is limited by the material properties of gratings. These limitations might be overcome through the use of plasma, which is an ideal medium for processing very high power and very high total energy. A plasma can be irradiated by a long pump laser pulse, carrying significant energy, which is then quickly depleted in the plasma by a short counterpropagating pulse. This counterpropagating wave effect has already been employed in Raman amplifiers using gases or plasmas at low laser power. Of particular interest here are the new effects which enter in high power regimes. These new effects can be employed so that one high-energy optical system can be used like a flashlamp in what amounts to pumping the plasma, and a second low-power optical system can be used to extract quickly the energy from the plasma and focus it precisely. The combined system can be very compact. Thus, focused intensities more than 10 25 W/cm 2 can be contemplated using existing optical elements. These intensities are several orders of magnitude higher than what is currently available through chirped pump amplifiers

Low-intensity pulsed ultrasound stimulation for mandibular condyle osteoarthritis lesions in rats.

Science.gov (United States)

Kanaguchi Arita, A; Yonemitsu, I; Ikeda, Y; Miyazaki, M; Ono, T

2018-05-01

This study evaluated low-intensity pulsed ultrasound effects for temporomandibular joint osteoarthritis in adult rats. Osteoarthritis-like lesions were induced in 24 adult rats' temporomandibular joints with low-dose mono-iodoacetate injections. The rats were divided into four groups: control and mono-iodoacetate groups, injected with contrast media and mono-iodoacetate, respectively, at 12 weeks and observed until 20 weeks; and low-intensity pulsed ultrasound and mono-iodoacetate + low-intensity pulsed ultrasound groups, injected with contrast media and mono-iodoacetate, respectively, at 12 weeks with low-intensity pulsed ultrasound performed from 16 to 20 weeks. Condylar bone mineral density, bone mineral content and bone volume were evaluated weekly with microcomputed tomography. Histological and immunohistochemical staining for matrix metalloproteinases-13 was performed at 20 weeks. At 20 weeks, the mono-iodoacetate + low-intensity pulsed ultrasound group showed significantly higher bone mineral density, bone mineral content and bone volume than the mono-iodoacetate group; however, these values remained lower than those in the other two groups. On histological and immunohistochemical analysis, the chondrocytes were increased, and fewer matrix metalloproteinases-13 immunopositive cells were identified in the mono-iodoacetate + low-intensity pulsed ultrasound group than mono-iodoacetate group. Low-intensity pulsed ultrasound for 2 weeks may have therapeutic potential for treating temporomandibular joint osteoarthritis lesions. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

High-intensity pulsed electric field variables affecting Staphylococcus aureus inoculated in milk.

Science.gov (United States)

Sobrino-López, A; Raybaudi-Massilia, R; Martín-Belloso, O

2006-10-01

Staphylococcus aureus is an important milk-related pathogen that is inactivated by high-intensity pulsed electric fields (HIPEF). In this study, inactivation of Staph. aureus suspended in milk by HIPEF was studied using a response surface methodology, in which electric field intensity, pulse number, pulse width, pulse polarity, and the fat content of milk were the controlled variables. It was found that the fat content of milk did not significantly affect the microbial inactivation of Staph. aureus. A maximum value of 4.5 log reductions was obtained by applying 150 bipolar pulses of 8 mus each at 35 kV/cm. Bipolar pulses were more effective than those applied in the monopolar mode. An increase in electric field intensity, pulse number, or pulse width resulted in a drop in the survival fraction of Staph. aureus. Pulse widths close to 6.7 micros lead to greater microbial death with a minimum number of applied pulses. At a constant treatment time, a greater number of shorter pulses achieved better inactivation than those treatments performed at a lower number of longer pulses. The combined action of pulse number and electric field intensity followed a similar pattern, indicating that the same fraction of microbial death can be reached with different combinations of the variables. The behavior and relationship among the electrical variables suggest that the energy input of HIPEF processing might be optimized without decreasing the microbial death.

Experimental study of carbon materials behavior under high temperature and VUV radiation: Application to Solar Probe+ heat shield

International Nuclear Information System (INIS)

Eck, J.; Sans, J.-L.; Balat-Pichelin, M.

2011-01-01

The aim of the Solar Probe Plus (SP+) mission is to understand how the solar corona is heated and how the solar wind is accelerated. To achieve these goals, in situ measurements are necessary and the spacecraft has to approach the Sun as close as 9.5 solar radii. This trajectory induces extreme environmental conditions such as high temperatures and intense Vacuum Ultraviolet radiation (VUV). To protect the measurement and communication instruments, a heat shield constituted of a carbon material is placed on the top of the probe. In this study, the physical and chemical behavior of carbon materials is experimentally investigated under high temperatures (1600-2100 K), high vacuum (10 -4 Pa) and VUV radiation in conditions near those at perihelion for SP+. Thanks to several in situ and ex situ characterizations, it was found that VUV radiation induced modification of outgassing and of mass loss rate together with alteration of microstructure and morphology.

Photodissociation of H2+ by intense chirped pulses - beyond the effect of pulse duration and peak power

International Nuclear Information System (INIS)

Lev, U; Prabhudesai, V; Natan, A; Bruner, B; Diner, A; Heber, O; Strasser, D; Schwalm, D; Silberberg, Y; Zajfman, D; Ben-Itzhak, I; Hua, J J; Esry, B D

2009-01-01

H 2 + photodissociation, induced by intense short laser pulses, was measured by a full 3D imaging system. We have conducted a series of experiments, in which we systematically changed the linear chirp, using a pulse shaper, and observed the kinetic energy release spectra(KER). Distinct differences in the KER spectra are observed both in peak positions and angular distribution for laser pulses with similar duration and intensity but opposite chirp sign.

Prepulse effect on intense femtosecond laser pulse propagation in gas

International Nuclear Information System (INIS)

Giulietti, Antonio; Tomassini, Paolo; Galimberti, Marco; Giulietti, Danilo; Gizzi, Leonida A.; Koester, Petra; Labate, Luca; Ceccotti, Tiberio; D'Oliveira, Pascal; Auguste, Thierry; Monot, Pascal; Martin, Philippe

2006-01-01

The propagation of an ultrashort laser pulse can be affected by the light reaching the medium before the pulse. This can cause a serious drawback to possible applications. The propagation in He of an intense 60-fs pulse delivered by a Ti:sapphire laser in the chirped pulse amplification (CPA) mode has been investigated in conditions of interest for laser-plasma acceleration of electrons. The effects of both nanosecond amplified spontaneous emission and picosecond pedestals have been clearly identified. There is evidence that such effects are basically of refractive nature and that they are not detrimental for the propagation of a CPA pulse focused to moderately relativistic intensity. The observations are fully consistent with numerical simulations and can contribute to the search of a stable regime for laser acceleration

Performance of the intense pulsed neutron source accelerator system

International Nuclear Information System (INIS)

Potts, C.; Brumwell, F.; Rauchas, A.; Stipp, V.; Volk, G.

1983-01-01

The Intense Pulsed Neutron Source (IPNS) facility has now been operating in a routine way for outside users since November 1, 1981. From that date through December of 1982, the accelerator system was scheduled for neutron science for 4500 hours. During this time the accelerator achieved its short-term goals by delivering about 380,000,000 pulses of beam totaling over 6 x 10 20 protons. The changes in equipment and operating practices that evolved during this period of intense running are described. The intensity related instability threshold was increased by a factor of two and the accelerator beam current has been ion source limited. Plans to increase the accelerator intensity are also described. Initial operating results with a new H - ion source are discussed

Recent performance of the Intense Pulsed Neutron Source accelerator system

International Nuclear Information System (INIS)

Potts, C.; Brumwell, F.; Rauchas, A.; Stipp, V.; Volk, G.; Donley, L.

1987-03-01

The Intense Pulsed Neutron Source (IPNS) accelerator system has now been in operation as part of a national user program for over five years. During that period steady progress has been made in both beam intensity and reliability. Almost 1.8 billion pulses totaling 4 x 10 21 protons have now been delivered to the spallation neutron target. Recent weekly average currents have reached 15 μA (3.2 x 10 12 protons per pulse, 30 pulses per second) and short-term peaks of almost 17 μA have been reached. In fact, the average current for the last two years is up 31% over the average for the first three years of operation

Self-resonant wakefield excitation by intense laser pulse in plasmas

International Nuclear Information System (INIS)

Andreev, N.E.; Pogosova, A.A.; Gorbunov, L.M.; Ramazashvili, R.R.; Kirsanov, V.I.

1993-01-01

It is demonstrated by theoretical analysis and numerical calculations that in an underdense plasma the process of three-dimensional evolution of the short and strong laser pulse (with duration equal to several plasma periods) leads to compression and self-modulation of the pulse, so that during a fairly long period of time beats of pulse amplitude generates resonantly a strong and stable plasma wakefield. The intensity of the wake-field is so high that it can provide a new promising outlook for the plasma based accelerator concept. Linear analysis of dispersion relation predicts that taking into account transverse component of wavenumber considerably increases the growth rate of resonance instability of the pulse. The numerical simulations demonstrate that considered self-focusing and resonant-modulation instability are essentially three dimensional processes. Laser field evolution in each transverse cross section of the pulse is synchronized by the regular structure of plasma wave that is excited by the pulse. The considered effect of resonant modulation has a threshold. For the pulses with the intensity below the threshold the refraction dominates and no modulation appears. The studied phenomenon can be referred to as the Self-Resonant Wakefield (SRWF) excitation that is driven by self-focusing and self-modulation of laser pulse with quite a moderate initial duration. In fact, this method of excitation differs from both suggested in Ref.1 (PBWA) and in Refs.2,3 (LWFA), being even more than the combination of these concepts. Unlike the first scheme it does not require initially the two-frequency laser pulse, since the modulation here appears in the most natural way due to evolution of the pulse. In contrast with the LWFA, the considered SRWF generation scheme gives the possibility to raise the intensity of wake-excitation due to pulse self-focusing ( initial stage) and self modulation (second stage)

Development of bipolar-pulse accelerator for intense pulsed ion beam acceleration

Energy Technology Data Exchange (ETDEWEB)

Masugata, Katsumi [Department of Electrical and Electronic System Engineering, Toyama University, 3190 Gofuku, Toyama 930-8555 (Japan)]. E-mail: masugata@eng.toyama-u.ac.jp; Shimizu, Yuichro [Department of Electrical and Electronic System Engineering, Toyama University, 3190 Gofuku, Toyama 930-8555 (Japan); Fujioka, Yuhki [Department of Electrical and Electronic System Engineering, Toyama University, 3190 Gofuku, Toyama 930-8555 (Japan); Kitamura, Iwao [Department of Electrical and Electronic System Engineering, Toyama University, 3190 Gofuku, Toyama 930-8555 (Japan); Tanoue, Hisao [National Institute of Advanced Industry Science and Technology, 1-1-1, Umezono, Tsukuba-shi, Ibaraki 305-8568 (Japan); Arai, Kazuo [National Institute of Advanced Industry Science and Technology, 1-1-1, Umezono, Tsukuba-shi, Ibaraki 305-8568 (Japan)

2004-12-21

To improve the purity of intense pulsed ion beams, a new type of pulsed ion beam accelerator named 'bipolar pulse accelerator' was proposed. To confirm the principle of the accelerator a prototype of the experimental system was developed. The system utilizes By type magnetically insulated acceleration gap and operated with single polar negative pulse. A coaxial gas puff plasma gun was used as an ion source, which was placed inside the grounded anode. Source plasma (nitrogen) of current density {approx}25A/cm2, duration {approx}1.5{mu}s was injected into the acceleration gap by the plasma gun. The ions were successfully accelerated from the grounded anode to the drift tube by applying negative pulse of voltage 240kV, duration 100ns to the drift tube. Pulsed ion beam of current density {approx}40A/cm2, duration {approx}50ns was obtained at 41mm downstream from the anode surface. To evaluate the irradiation effect of the ion beam to solid material, an amorphous silicon thin film of thickness {approx}500nm was used as the target, which was deposited on the glass substrate. The film was found to be poly-crystallized after 4-shots of the pulsed nitrogen ion beam irradiation.

Design of ITER divertor VUV spectrometer and prototype test at KSTAR tokamak

Science.gov (United States)

Seon, Changrae; Hong, Joohwan; Song, Inwoo; Jang, Juhyeok; Lee, Hyeonyong; An, Younghwa; Kim, Bosung; Jeon, Taemin; Park, Jaesun; Choe, Wonho; Lee, Hyeongon; Pak, Sunil; Cheon, MunSeong; Choi, Jihyeon; Kim, Hyeonseok; Biel, Wolfgang; Bernascolle, Philippe; Barnsley, Robin; O'Mullane, Martin

2017-12-01

Design and development of the ITER divertor VUV spectrometer have been performed from the year 1998, and it is planned to be installed in the year 2027. Currently, the design of the ITER divertor VUV spectrometer is in the phase of detail design. It is optimized for monitoring of chord-integrated VUV signals from divertor plasmas, chosen to contain representative lines emission from the tungsten as the divertor material, and other impurities. Impurity emission from overall divertor plasmas is collimated through the relay optics onto the entrance slit of a VUV spectrometer with working wavelength range of 14.6-32 nm. To validate the design of the ITER divertor VUV spectrometer, two sets of VUV spectrometers have been developed and tested at KSTAR tokamak. One set of spectrometer without the field mirror employs a survey spectrometer with the wavelength ranging from 14.6 nm to 32 nm, and it provides the same optical specification as the spectrometer part of the ITER divertor VUV spectrometer system. The other spectrometer with the wavelength range of 5-25 nm consists of a commercial spectrometer with a concave grating, and the relay mirrors with the same geometry as the relay mirrors of the ITER divertor VUV spectrometer. From test of these prototypes, alignment method using backward laser illumination could be verified. To validate the feasibility of tungsten emission measurement, furthermore, the tungsten powder was injected in KSTAR plasmas, and the preliminary result could be obtained successfully with regard to the evaluation of photon throughput. Contribution to the Topical Issue "Atomic and Molecular Data and their Applications", edited by Gordon W.F. Drake, Jung-Sik Yoon, Daiji Kato, Grzegorz Karwasz.

Pulsed-low intensity ultrasound enhances extracellular matrix production by fibroblasts encapsulated in alginate

Directory of Open Access Journals (Sweden)

Siti PM Bohari

2012-12-01

Full Text Available In this study, the effect of pulsed-low intensity ultrasound on cell proliferation, collagen production and glycosaminoglycan deposition by 3T3 fibroblasts encapsulated in alginate was evaluated. Hoechst 33258 assay for cell number, hydroxyproline assay for collagen content and dimethylamine blue assay for glycosaminoglycan content were performed on samples from cell cultures treated with pulsed-low intensity ultrasound and a control group. Pulsed-low intensity ultrasound shows no effect on cell proliferation, while collagen and glycosaminoglycan contents were consistently higher in the samples treated with pulsed-low intensity ultrasound, showing a statistically significant difference (p < 0.05 on day 10. Alcian blue staining showed that glycosaminoglycans were deposited around the cells in both groups. These results suggest that pulsed-low intensity ultrasound shows no effect on cell proliferation but has potential for inducing collagen and glycosaminoglycan production in cells cultured in alginate gels.

Update on VUV and soft X-ray facilities at SSRL

International Nuclear Information System (INIS)

Waldhauer, A.

1988-01-01

The number of experimental stations at SSRL devoted to the VUV and soft X-ray region is increasing rapidly. In 1986 there were five VUV/soft X-ray beam lines in regular operation. These consisted of two grasshopper lines, a Seya-Namioka line, a white light lithography line, and the UHV double crystal line, Jumbo. By 1988 ten beam lines, including two with insertion devices, covering the spectral range 5-4000 eV in five overlapping ranges will be operational. With the addition of these new stations, SSRL will have increased dramatically its facilities for performing VUV and soft X-ray research. (orig.)

UV and VUV photolysis vs. UV/H2O2 and VUV/H2O2, treatment for removal of clofibric acid from aqueous solution.

Science.gov (United States)

Li, Wenzhen; Lu, Shuguang; Qiu, Zhaofu; Lin, Kuangfei

2011-07-01

Clofibric acid (CA), a metabolite of lipid regulators, was investigated in ultra-pure water and sewage treatment plant (STP) effluent at 10 degrees C under UV, vacuum UV (VUV), UV/H2O2 and VUV/H2O2 processes. The influences of NO3-, HCO3- and humic acid (HA) on CA photolysis in all processes were examined. The results showed that all the experimental data well fitted the pseudo-first-order kinetic model, and the apparent rate constant (k(ap)) and half-life time (t(1/2)) were calculated accordingly. Direct photolysis of CA through UV irradiation was the main process, compared with the indirect oxidation of CA due to the slight generation of hydroxyl radicals dissociated from water molecules under UV irradiation below 200 nm monochromatic wavelength emission. In contrast, indirect oxidation was the main CA degradation mechanism in UV/H2O2 and VUV/H2O2, and VUV/H2O2 was the most effective process for CA degradation. The addition of 20 mg L(-1) HA could significantly inhibit CA degradation, whereas, except for UV irradiation, the inhibitive effects of NO3- and HCO3- (1.0 x 10(-3) and 0.1 mol L(-1), respectively) on CA degradation were observed in all processes, and their adverse effects were more significant in UV/H2O2 and VUV/H2O2 processes, particularly at the high NO3- and HCO3- concentrations. The degradation rate decreased 1.8-4.9-fold when these processes were applied to a real STP effluent owing to the presence of complex constituents. Of the four processes, VUV/H2O2 was the most effective, and the CA removal efficiency reached over 99% after 40 min in contrast to 80 min in both the UV/H2O2 and VUV processes and 240 min in the UV process.

Ultrashort x-ray pulse generation by nonlinear Thomson scattering of a relativistic electron with an intense circularly polarized laser pulse

Directory of Open Access Journals (Sweden)

F. Liu

2012-07-01

Full Text Available The nonlinear Thomson scattering of a relativistic electron with an intense laser pulse is calculated numerically. The results show that an ultrashort x-ray pulse can be generated by an electron with an initial energy of 5 MeV propagating across a circularly polarized laser pulse with a duration of 8 femtosecond and an intensity of about 1.1×10^{21}  W/cm^{2}, when the detection direction is perpendicular to the propagation directions of both the electron and the laser beam. The optimal values of the carrier-envelop phase and the intensity of the laser pulse for the generation of a single ultrashort x-ray pulse are obtained and verified by our calculations of the radiation characteristics.

Influence of gas discharge parameters on emissions from a dielectric barrier discharge excited argon excimer lamp

Directory of Open Access Journals (Sweden)

Mike Collier

2011-11-01

Full Text Available A dielectric barrier discharge excited neutral argon (Ar I excimer lamp has been developed and characterised. The aim of this study was to develop an excimer lamp operating at atmospheric pressure that can replace mercury lamps and vacuum equipment used in the sterilisation of medical equipment and in the food industry. The effects of discharge gas pressure, flow rate, excitation frequency and pulse width on the intensity of the Ar I vacuum ultraviolet (VUV emission at 126 nm and near infrared (NIR lines at 750.4 nm and 811.5 nm have been investigated. These three lines were chosen as they represent emissions resulting from de-excitation of excimer states that emit energetic photons with an energy of 9.8 eV. We observed that the intensity of the VUV Ar₂* excimer emission at 126 nm increased with increasing gas pressure, but decreased with increasing excitation pulse frequency and pulse width. In contrast, the intensities of the NIR lines decreased with increasing gas pressure and increased with increasing pulse frequency and pulse width. We have demonstrated that energetic VUV photons of 9.8 eV can be efficiently generated in a dielectric barrier discharge in Ar.

Intense pulsed neutron source accelerator status

International Nuclear Information System (INIS)

Potts, C.W.; Brumwell, F.R.; Stipp, V.F.

1983-01-01

The Intense Pulsed Neutron Source (IPNS) facility has been in operation since November 1, 1981. From that date through August 1, 1983, the accelerator system was scheduled for 7191 hours of operation. During this period, 627 million pulses totaling about 1.1 x 10 21 protons were delivered to the spallation target. The accelerator has exceeded goals set in 1981 by averaging 8.65 μA over this two year period. This average beam current, while modest by the standards of proposed machines, makes the IPNS synchrotron (Rapid Cycling Synchrotron [RCS]) the highest intensity proton synchrotron in the world today. Detailed data on accelerator operation are presented. Weekly average currents of 12 μA have been achieved along with peaks of 13.9 μA. A great deal has been learned about the required operating constraints during high beam current operation. It should be possible to increase the average beam current during this next year to 12 μA while observing these restraints. Improvement plans have been formulated to increase the beam current to 16 μA over the next three years

Intense pulsed heavy ion beam technology

International Nuclear Information System (INIS)

Masugata, Katsumi; Ito, Hiroaki

2010-01-01

Development of intense pulsed heavy ion beam accelerator technology is described for the application of materials processing. Gas puff plasma gun and vacuum arc discharge plasma gun were developed as an active ion source for magnetically insulated pulsed ion diode. Source plasma of nitrogen and aluminum were successfully produced with the gas puff plasma gun and the vacuum arc plasma gun, respectively. The ion diode was successfully operated with gas puff plasma gun at diode voltage 190 kV, diode current 2.2 kA and nitrogen ion beam of ion current density 27 A/cm 2 was obtained. The ion composition was evaluated by a Thomson parabola spectrometer and the purity of the nitrogen ion beam was estimated to be 86%. The diode also operated with aluminum ion source of vacuum arc plasma gun. The ion diode was operated at 200 kV, 12 kA, and aluminum ion beam of current density 230 A/cm 2 was obtained. The beam consists of aluminum ions (Al (1-3)+ ) of energy 60-400 keV, and protons (90-130 keV), and the purity was estimated to be 89%. The development of the bipolar pulse accelerator (BPA) was reported. A double coaxial type bipolar pulse generator was developed as the power supply of the BPA. The generator was tested with dummy load of 7.5 ohm, bipolar pulses of -138 kV, 72 ns (1st pulse) and +130 kV, 70 ns (2nd pulse) were successively generated. By applying the bipolar pulse to the drift tube of the BPA, nitrogen ion beam of 2 A/cm 2 was observed in the cathode, which suggests the bipolar pulse acceleration. (author)

Degradation of Solar Array Components in a Combined UV/VUV High Temperature Test Environment

Directory of Open Access Journals (Sweden)

Nömayr Christel

2017-01-01

A design verification test under UV/VUV conditions of sun exposed materials and technologies on component level is presented which forms part of the overall verification and qualification of the solar array design of the MTM and MPO. The test concentrates on the self-contamination aspects and the resulting performance losses of the solar array under high intensity and elevated temperature environment representative for the photovoltaic assembly (PVA.

Photocatalytic oxidation of indoor toluene: Process risk analysis and influence of relative humidity, photocatalysts, and VUV irradiation

International Nuclear Information System (INIS)

Zhao, Weirong; Dai, Jiusong; Liu, Feifei; Bao, Jiaze; Wang, Yan; Yang, Yong; Yang, Yanan; Zhao, Dongye

2012-01-01

Concentrations of 13 gaseous intermediates in photocatalytic oxidation (PCO) of toluene in indoor air were determined in real-time by proton transfer reaction mass spectrometry and desorption intensities of 7 adsorbed intermediates on the surface of photocatalysts were detected by temperature‐programmed desorption‐mass spectrometry. Effects of relative humidity (RH), photocatalysts, and vacuum ultraviolet (VUV) irradiation on the distribution and category of the intermediates and health risk influence index (η) were investigated. RH enhances the formation rate of hydroxide radicals, leading to more intermediates with higher oxidation states in gas phase. N doping promotes the separation of photo-generated electrons and holes and enhances PCO activity accordingly. VUV irradiation results in higher mineralization rate and more intermediates with higher oxidation states and lower toxicity e.g. carboxylic acids. Health risk analysis indicates that higher RH, N doping of TiO 2 , and VUV lead to “greener” intermediates and smaller η. Finally, a conceptual diagram was proposed to exhibit the scenario of η varied with extent of mineralization for various toxicities of inlet pollutants. Highlights: ► 13 volatile intermediates in PCO of toluene were determined in real-time by PTR-MS. ► 7 adsorbed intermediates on surface of photocatalyst were determined by TPD-MS. ► Higher RH, N doping of TiO 2 , and VUV irradiation lead to “greener” intermediates. ► Health risk index relies on extent of mineralization and toxicities of inlet VOCs.

Frequency conversion of high-intensity, femtosecond laser pulses

Energy Technology Data Exchange (ETDEWEB)

Banks, P S

1997-06-01

Almost since the invention of the laser, frequency conversion of optical pulses via non- linear processes has been an area of active interest. However, third harmonic generation using ~(~1 (THG) in solids is an area that has not received much attention because of ma- terial damage limits. Recently, the short, high-intensity pulses possible with chirped-pulse amplification (CPA) laser systems allow the use of intensities on the order of 1 TW/cm2 in thin solids without damage. As a light source to examine single-crystal THG in solids and other high field inter- actions, the design and construction of a Ti:sapphire-based CPA laser system capable of ultimately producing peak powers of 100 TW is presented. Of special interest is a novel, all-reflective pulse stretcher design which can stretch a pulse temporally by a factor of 20,000. The stretcher design can also compensate for the added material dispersion due to propagation through the amplifier chain and produce transform-limited 45 fs pulses upon compression. A series of laser-pumped amplifiers brings the peak power up to the terawatt level at 10 Hz, and the design calls for additional amplifiers to bring the power level to the 100 TW level for single shot operation. The theory for frequency conversion of these short pulses is presented, focusing on conversion to the third harmonic in single crystals of BBO, KD*P, and d-LAP (deuterated I-arginine phosphate). Conversion efficiencies of up to 6% are obtained with 500 fs pulses at 1053 nm in a 3 mm thick BBO crystal at 200 GW/cm 2. Contributions to this process by unphasematched, cascaded second harmonic generation and sum frequency generation are shown to be very significant. The angular relationship between the two orders is used to measure the tensor elements of C = xt3)/4 with Crs = -1.8 x 1O-23 m2/V2 and .15Cri + .54Crs = 4.0 x 1O-23 m2/V2. Conversion efficiency in d-LAP is about 20% that in BBO and conversion efficiency in KD*P is 1% that of BBO. It is calculated

High intensity pulse self-compression in short hollow core capillaries

OpenAIRE

Butcher, Thomas J.; Anderson, Patrick N.; Horak, Peter; Frey, Jeremy G.; Brocklesby, William S.

2011-01-01

The drive for shorter pulses for use in techniques such as high harmonic generation and laser wakefield acceleration requires continual improvement in post-laser pulse compression techniques. The two most commonly used methods of pulse compression for high intensity pulses are hollow capillary compression via self-phase modulation (SPM) [1] and the more recently developed filamentation [2]. Both of these methods can require propagation distances of 1-3 m to achieve spectral broadening and com...

Photodissociation of H{sub 2}{sup +} by intense chirped pulses - beyond the effect of pulse duration and peak power

Energy Technology Data Exchange (ETDEWEB)

Lev, U; Prabhudesai, V; Natan, A; Bruner, B; Diner, A; Heber, O; Strasser, D; Schwalm, D; Silberberg, Y; Zajfman, D [Faculty of Physics, Weizmann Institute of Science, Rehovot 76100 (Israel); Ben-Itzhak, I; Hua, J J; Esry, B D, E-mail: uri.lev@Weizmann.ac.i [Department of Physics, Kansas State University, Manhattan, KS 66506 (United States)

2009-11-01

H{sub 2}{sup +} photodissociation, induced by intense short laser pulses, was measured by a full 3D imaging system. We have conducted a series of experiments, in which we systematically changed the linear chirp, using a pulse shaper, and observed the kinetic energy release spectra(KER). Distinct differences in the KER spectra are observed both in peak positions and angular distribution for laser pulses with similar duration and intensity but opposite chirp sign.

A photodiode amplifier system for pulse-by-pulse intensity measurement of an x-ray free electron laser.

Science.gov (United States)

Kudo, Togo; Tono, Kensuke; Yabashi, Makina; Togashi, Tadashi; Sato, Takahiro; Inubushi, Yuichi; Omodani, Motohiko; Kirihara, Yoichi; Matsushita, Tomohiro; Kobayashi, Kazuo; Yamaga, Mitsuhiro; Uchiyama, Sadayuki; Hatsui, Takaki

2012-04-01

We have developed a single-shot intensity-measurement system using a silicon positive-intrinsic-negative (PIN) photodiode for x-ray pulses from an x-ray free electron laser. A wide dynamic range (10(3)-10(11) photons/pulse) and long distance signal transmission (>100 m) were required for this measurement system. For this purpose, we developed charge-sensitive and shaping amplifiers, which can process charge pulses with a wide dynamic range and variable durations (ns-μs) and charge levels (pC-μC). Output signals from the amplifiers were transmitted to a data acquisition system through a long cable in the form of a differential signal. The x-ray pulse intensities were calculated from the peak values of the signals by a waveform fitting procedure. This system can measure 10(3)-10(9) photons/pulse of ~10 keV x-rays by direct irradiation of a silicon PIN photodiode, and from 10(7)-10(11) photons/pulse by detecting the x-rays scattered by a diamond film using the silicon PIN photodiode. This system gives a relative accuracy of ~10(-3) with a proper gain setting of the amplifiers for each measurement. Using this system, we succeeded in detecting weak light at the developmental phase of the light source, as well as intense light during lasing of the x-ray free electron laser. © 2012 American Institute of Physics

SiPM response to long and intense light pulses

Energy Technology Data Exchange (ETDEWEB)

Vinogradov, S., E-mail: Sergey.Vinogradov@liverpool.ac.uk [University of Liverpool and Cockcroft Institute, Sci-Tech Daresbury, Keckwick Lane, Warrington WA4 4AD (United Kingdom); P.N. Lebedev Physical Institute of the Russian Academy of Sciences, 119991 Leninskiy prospekt 53, Moscow (Russian Federation); Arodzero, A. [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 (United States); RadiaBeam Technologies Inc., 1717 Stewart St., Santa Monica, CA 90404 (United States); Lanza, R.C. [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 (United States); Welsch, C.P. [University of Liverpool and Cockcroft Institute, Sci-Tech Daresbury, Keckwick Lane, Warrington WA4 4AD (United Kingdom)

2015-07-01

Recently Silicon Photomultipliers (SiPMs) have become well recognized as the detector of choice for various applications which demand good photon number resolution and time resolution of short weak light pulses in the nanosecond time scale. In the case of longer and more intensive light pulses, SiPM performance gradually degrades due to dark noise, afterpulsing, and non-instant cell recovering. Nevertheless, SiPM benefits are expected to overbalance their drawbacks in applications such as X-ray cargo inspection using Scintillation-Cherenkov detectors and accelerator beam loss monitoring with Cherenkov fibres, where light pulses of a microsecond time scale have to be detected with good amplitude and timing resolution in a wide dynamic range of 10{sup 5}–10{sup 6}. This report is focused on transient characteristics of a SiPM response on a long rectangular light pulse with special attention to moderate and high light intensities above the linear dynamic range. An analytical model of the transient response and an initial consideration of experimental results in comparison with the model are presented.

Imaging monitored loosening of dense fibrous tissues using high-intensity pulsed ultrasound

International Nuclear Information System (INIS)

Yeh, Chia-Lun; Li, Pai-Chi; Kuo, Po-Ling; Shih, Wen-Pin; Huang, Pei-Shin

2013-01-01

Pulsed high-intensity focused ultrasound (HIFU) is proposed as a new alternative treatment for contracture of dense fibrous tissue. It is hypothesized that the pulsed-HIFU can release the contracted tissues by attenuating tensile stiffness along the fiber axis, and that the stiffness reduction can be quantitatively monitored by change of B-mode images. Fresh porcine tendons and ligaments were adapted to an ex vivo model and insonated with pulsed-HIFU for durations ranging from 5 to 30 min. The pulse length was 91 µs with a repetition frequency of 500 Hz, and the peak rarefactional pressure was 6.36 MPa. The corresponding average intensities were kept around 1606 W cm −2 for I SPPA and 72.3 W cm −2 for I SPTA . B-mode images of the tissues were acquired before and after pulsed-HIFU exposure, and the changes in speckle intensity and organization were analyzed. The tensile stiffness of the HIFU-exposed tissues along the longitudinal axis was examined using a stretching machine. Histology examinations were performed by optical and transmission electron microscopy. Pulsed-HIFU exposure significantly decreased the tensile stiffness of the ligaments and tendons. The intensity and organization of tissue speckles in the exposed region were also decreased. The speckle changes correlated well with the degree of stiffness alteration. Histology examinations revealed that pulsed-HIFU exposure probably damages tissues via a cavitation-mediated mechanism. Our results suggest that pulsed-HIFU with a low duty factor is a promising tool for developing new treatment strategies for orthopedic disorders. (paper)

Coherent combs in ionization by intense and short laser pulses

Energy Technology Data Exchange (ETDEWEB)

Krajewska, K., E-mail: Katarzyna.Krajewska@fuw.edu.pl [Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warszawa (Poland); Department of Physics and Astronomy, University of Nebraska, Lincoln, NE 68588-0299 (United States); Kamiński, J.Z., E-mail: Jerzy.Kaminski@fuw.edu.pl [Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warszawa (Poland)

2016-03-22

Photoionization of positive ions by a train of intense, short laser pulses is investigated within the relativistic strong field approximation, using the velocity gauge. The formation of broad peak structures in the high-energy domain of photoelectrons is observed and interpreted. The emergence of coherent photoelectron energy combs within these structures is demonstrated, and it is interpreted as the consequence of the Fraunhofer-type interference/diffraction of probability amplitudes of ionization from individual pulses comprising the train. Extensions to the coherent angular combs are also studied, and effects related to the radiation pressure are presented. - Highlights: • We develop relativistic Strong-Field Approximation for ionization by intense and short laser pulses of arbitrary spectral compositions. • We show that the consistent interpretation of results is provided by the Keldysh-type saddle point analysis of probability amplitudes. • We derive a general Fraunhofer-type interference/diffraction formula for finite train of pulses. • We study the coherent combs in photoelectron probability distributions.

A study of enhanced performance of VUV/UV process for the degradation of micropollutants from contaminated water

Energy Technology Data Exchange (ETDEWEB)

Bagheri, Mehdi; Mohseni, Madjid, E-mail: madjid.mohseni@ubc.ca

2015-08-30

Highlights: • Developing a comprehensive CFD simulation tool for VUV/UV photoreactors modeling. • Analysing impact of reactor hydrodynamics on the AOP performance of VUV/UV process. • Cutting the energy cost of VUV/UV process by means of improved-photoreactor design. • Experimentally verifying the CFD results using a VUV/UV prototype photoreactor. - Abstract: VUV/UV is a chemical-free and straightforward solution for the degradation of emerging contaminants from water sources. The objective of this work was to investigate the feasibility of VUV/UV advanced oxidation process for the effective degradation of a target micropollutant, atrazine, under continuous flow operation of 0.5–6.5 L/min. To provide an in-depth understanding of process, a comprehensive computational fluid dynamics (CFD) model, incorporating flow hydrodynamics, 185 nm VUV and 254 nm UV radiation propagation along with a complete kinetic scheme, was developed and validated experimentally. The experimental degradation rates and CFD predicted values showed great consistency with less than 2.9% average absolute relative deviation (AARD). Utilizing the verified model, energy-efficiency of the VUV/UV process under a wide range of reactor configurations was assessed in terms of electrical energy-per-order (EEO), ·OH concentration as well as delivered UV and VUV dose distributions. Thereby, the extent of mixing and circulation zones was found as key parameter controlling the treatment economy and energy-efficiency of the VUV/UV process. Utilizing a CFD-driven baffle design strategy, an improved VUV/UV process with up to 72% reduction in the total electrical energy requirement of atrazine degradation was introduced and verified experimentally.

Attosecond pulse generation in noble gases in the presence of extreme high intensity THz pulses

International Nuclear Information System (INIS)

Balogh, E.; Varju, K.

2010-01-01

Complete text of publication follows. The shortest - attosecond - light pulses available today are produced by high harmonic generation (HHG) of near-infrared (NIR) laser pulses in noble gas jets, providing a broad spectral plateau of XUV radiation ending in a cutoff. The minimum pulse duration is determined by the achievable bandwidth (i.e. the position of the cutoff), and the chirp of the produced pulses. The extension of the cutoff by increasing the laser intensity is limited by the depletion and phase matching problems of the medium. An alternative method demonstrated to produce higher harmonic orders is by using longer pump pulse wavelength, with the disadvantage of decreased efficiency. Recently it was shown that application of a quasi-DC high strength electric field results in an increase of more than a factor of two in the order of efficiently generated high harmonics. However, the possibility to implement the method proposed in [3] of using a CO 2 laser to create a quasi-DC field for assisting HHG of the NIR laser is questionable, because it's technically very challenging to synchronize pulses from different laser sources. Alternatively, synchronous production of THz pulses with the NIR laser pulse offers a more promising route. The first numerical test of this idea has been reported in [4]. In this contribution we further investigate the method for realistic THz field strengths and short driving pulses, exploring the effect of longer pump laser wavelength on the process. We assume the presence of high intensity THz pulses for supplying the high-strength quasi-DC electric field. The spectrum as well as the chirp of the produced radiation is calculated. We use the non-adiabatic saddle point method to determine the generated radiation described in [6]. We simulate harmonic generation in noble gas atoms, with few cycle NIR pulses of peak intensity at and above 2 x 10 14 W/cm 2 (388 MV/cm) and wavelengths 800 nm and 1560 nm. The THz field strength is varied

Towards attosecond X-ray pulses from the FEL

International Nuclear Information System (INIS)

Zholents, Alexander A.; Fawley, William M.

2004-01-01

The ability to study ultrafast phenomena has been recently advanced by the demonstrated production and measurement of a single, 650-attosecond (10 18 sec), VUV x-ray pulse[1] and, latter, a 250-attosecond pulse[2]. The next frontier is a production of the x-ray pulses with shorter wavelengths and in a broader spectral range. Several techniques for a generation of an isolated, attosecond duration, short-wavelength x-ray pulse based upon the ponderomotive laser acceleration [3], SASE and harmonic cascade FELs ([4] - [6]) had been already proposed. In this paper we briefly review a technique proposed in [5] and present some new results

The role of lasers and intense pulsed light technology in dermatology

Directory of Open Access Journals (Sweden)

Husain Z

2016-02-01

Full Text Available Zain Husain,1 Tina S Alster1,2 1Department of Dermatology, Georgetown University Hospital, 2Washington Institute of Dermatologic Laser Surgery, Washington, DC, USA Abstract: The role of light-based technologies in dermatology has expanded dramatically in recent years. Lasers and intense pulsed light have been used to safely and effectively treat a diverse array of cutaneous conditions, including vascular and pigmented lesions, tattoos, scars, and undesired hair, while also providing extensive therapeutic options for cosmetic rejuvenation and other dermatologic conditions. Dermatologic laser procedures are becoming increasingly popular worldwide, and demand for them has fueled new innovations and clinical applications. These systems continue to evolve and provide enhanced therapeutic outcomes with improved safety profiles. This review highlights the important roles and varied clinical applications that lasers and intense pulsed light play in the dermatologic practice. Keywords: laser, intense pulsed light, treatment, dermatology, technology

VUV optical ring resonator for Duke storage ring free electron laser

Energy Technology Data Exchange (ETDEWEB)

Park, S.H.; Litvinenko, V.N.; Madey, J.M.J. [Duke Univ., Durham, NC (United States)] [and others

1995-12-31

The conceptual design of the multifaceted-mirror ring resonator for Duke storage ring VUV FEL is presented. The expected performance of the OK-4 FEL with ring resonator is described. We discuss in this paper our plans to study reflectivity of VUV mirrors and their resistivity to soft X-ray spontaneous radiation from OK-4 undulator.

Propagation of intense laser pulses in an underdense plasma

International Nuclear Information System (INIS)

Monot, P.; Auguste, T.; Gibbon, P.; Jakober, F.; Mainfray, G.

1994-01-01

Experiments carried out with a laser beam focused into a vacuum chamber onto a 3-mm long, pulsed hydrogen jet, at powers close to the critical power required for relativistic self focusing, have shown that an underdense plasma is able to significantly reduce the divergence of an intense laser pulse. The propagation mode is in good agreement with theoretical predictions of relativistic self focusing. 2 figs., 8 refs

UV-VUV FEL program at DUKE storage ring with OK-4 optical klystron

International Nuclear Information System (INIS)

Litvinenko, V.N.; Madey, J.M.J.; Vinokurov, N.A.

1993-01-01

A 1 GeV electron storage ring dedicated for UV-VUV FEL operation is under construction at the Duke University Free Electron Laser Laboratory. The UV-VUV-FEL project, based on the collaboration of the Duke FEL Laboratory and Budker Institute for Nuclear Physics is described. The main parameters of the DFELL storage ring, of the OK-4 optical klystron, and the experimental set-up are presented. The parameters of UV-VUV FEL are given and the possible future upgrades to this system are discussed

Unconventional Use of Intense Pulsed Light

OpenAIRE

Piccolo, D.; Di Marcantonio, D.; Crisman, G.; Cannarozzo, G.; Sannino, M.; Chiricozzi, A.; Chimenti, S.

2014-01-01

According to the literature, intense pulsed light (IPL) represents a versatile tool in the treatment of some dermatological conditions (i.e., pigmentation disorders, hair removal, and acne), due to its wide range of wavelengths. The authors herein report on 58 unconventional but effective uses of IPL in several cutaneous diseases, such as rosacea (10 cases), port-wine stain (PWS) (10 cases), disseminated porokeratosis (10 cases), pilonidal cyst (3 cases), seborrheic keratosis (10 cases), hype...

Skinning of argon clusters by Coulomb explosion induced with an intense femtosecond laser pulse

International Nuclear Information System (INIS)

Sakabe, S.; Shirai, K.; Hashida, M.; Shimizu, S.; Masuno, S.

2006-01-01

The energy distributions of ions emitted from argon clusters Coulomb exploded at an intensity of 17 W/cm 2 with an intense femtosecond laser have been experimentally studied. The power m of energy E of the ion energy distribution (dN/dE∼E m ) is expected to be 1/2 for spherical ion clusters, but it is in fact reduced smaller than 1/2 as the laser intensity is decreased. This reduction can be well interpreted as resulting from the instantaneous ionization of the surface of the cluster. The validity of this interpretation was confirmed by experiments with double pulse irradiation. A cluster irradiated by the first pulse survives as a skinned cluster, and the remaining core part is Coulomb exploded by the second pulse. It is shown that a cluster can be skinned by an intense short laser pulse, and the laser-intensity dependence of the skinned layer thickness can be reasonably explained by the laser-induced space charge field created in the cluster

Plasma discreteness effects in the presence of an intense, ultrashort laser pulse

Energy Technology Data Exchange (ETDEWEB)

Savchenko, V.I.; Fisch, N.J.

1996-03-01

Discrete effects of the plasma irradiated by an ultrashort, intense laser pulse are investigated. Although, for most plasmas of interest, the damping of the laser pulse is due to collective plasma effects, in certain regimes the energy absorbed in the plasma microfields can be important. A scattering matrix is derived for an electron scattering off an ion in the presence of an intense laser field.

Plasma discreteness effects in the presence of an intense, ultrashort laser pulse

International Nuclear Information System (INIS)

Savchenko, V.I.; Fisch, N.J.

1996-03-01

Discrete effects of the plasma irradiated by an ultrashort, intense laser pulse are investigated. Although, for most plasmas of interest, the damping of the laser pulse is due to collective plasma effects, in certain regimes the energy absorbed in the plasma microfields can be important. A scattering matrix is derived for an electron scattering off an ion in the presence of an intense laser field

Characteristics of ionization chambers for intense pulsed x-rays and Co-60 #betta#-rays, (2)

International Nuclear Information System (INIS)

Kanazawa, Tamotsu; Okabe, Shigeru; Fukuda, Kyue; Furuta, Junichiro; Fujino, Takahiro

1981-01-01

Mean ionization currents and pulse figures of parallel plate ionization chambers enclosed with various gases were measured when they were exposed to intense pulsed X-rays and continuous #betta#-rays. Relation between the measured ionization current and the intensity of X-rays was obtained at the applied voltage of 1000 V. In the case of intense pulsed X-rays, ionization current was smaller in comparison with the case of continuous #betta#-rays, under the X-rays of equal intensity. Pulse figures were observed with chambers which were filled with the gases of air and O 2 and they are considered to be caused by the free electrons of these gases. In these cases, polarity effects of the electric field on the pulse figures were not recognized. Various figures and their changes were also observed from chambers filled with He, Ne, N 2 , Ar, kr, and Xe, respectively. Polarity effects were recognized on those pulse figures. (author)

VUV-soft x-ray beamline for spectroscopy and calibration

International Nuclear Information System (INIS)

Bartlett, R.J.; Trela, W.J.; Michaud, F.D.; Southworth, S.H.; Rothe, R.; Alkire, R.W.

1986-01-01

The authors describe the design and performance of the Los Alamos VUV synchrotron radiation beamline, U3C, on the VUV ring of the National Synchrotron Light Source at Brookhaven National Laboratory. The beamline uses separate function optics to collect and focus the horizontally and vertically diverging beam. The monochromator is a grazing incidence Roland circle instrument of the extended grasshopper design (ERG). A post monochromator refocusing mirror is used to focus or collimate the diverging beam from the monochromator. The beamline control and diagnostics systems are also discussed

Interaction of ultra-short ultra-intense laser pulses with under-dense plasmas

International Nuclear Information System (INIS)

Solodov, A.

2000-12-01

Different aspects of interaction of ultra-short ultra-intense laser pulses with underdense plasmas are studied analytically and numerically. These studies can be interesting for laser-driven electron acceleration in plasma, X-ray lasers, high-order harmonic generation, initial confinement fusion with fast ignition. For numerical simulations a fully-relativistic particle code WAKE was used, developed earlier at Ecole Polytechnique. It was modified during the work on the thesis in the part of simulation of ion motion, test electron motion, diagnostics for the field and plasma. The studies in the thesis cover the problems of photon acceleration in the plasma wake of a short intense laser pulse, phase velocity of the plasma wave in the Self-Modulated Laser Wake-Field Accelerator (SM LWFA), relativistic channeling of laser pulses with duration of the order of a plasma period, ion dynamics in the wake of a short intense laser pulse, plasma wave breaking. Simulation of three experiments on the laser pulse propagation in plasma and electron acceleration were performed. Among the main results of the thesis, it was found that reduction of the plasma wave phase velocity in the SM LWFA is crucial for electron acceleration, only if a plasma channel is used for the laser pulse guiding. Self-similar structures describing relativistic guiding of short laser pulses in plasmas were found and relativistic channeling of initially Gaussian laser pulses of a few plasma periods in duration was demonstrated. It was shown that ponderomotive force of a plasma wake excited by a short laser pulse forms a channel in plasma and plasma wave breaking in the channel was analyzed in detail. Effectiveness of electron acceleration by the laser field and plasma wave was compared and frequency shift of probe laser pulses by the plasma waves was found in conditions relevant to the current experiments. (author)

Low-intensity pulsed ultrasound (LIPUS) and pulsed electromagnetic field (PEMF) treatments affect degeneration of cultured articular cartilage explants

NARCIS (Netherlands)

Tan, Lijun; Ren, Yijin; van Kooten, Theo G.; Grijpma, Dirk W.; Kuijer, Roelof

PURPOSE: Articular cartilage has some capacity for self-repair. Clinically used low-intensity pulsed ultrasound (LIPUS) and pulsed electromagnetic field (PEMF) treatments were compared in their potency to prevent degeneration using an explant model of porcine cartilage. METHODS: Explants of porcine

Low-intensity pulsed ultrasound (LIPUS) and pulsed electromagnetic field (PEMF) treatments affect degeneration of cultured articular cartilage explants

NARCIS (Netherlands)

Tan, Lijun; Tan, Lijun; Ren, Yijin; van Kooten, Theo G.; Grijpma, Dirk W.; Kuijer, Roel

2015-01-01

Purpose: Articular cartilage has some capacity for self-repair. Clinically used low-intensity pulsed ultrasound (LIPUS) and pulsed electromagnetic field (PEMF) treatments were compared in their potency to prevent degeneration using an explant model of porcine cartilage. Methods: Explants of porcine

Low-k films modification under EUV and VUV radiation

International Nuclear Information System (INIS)

Rakhimova, T V; Rakhimov, A T; Mankelevich, Yu A; Lopaev, D V; Kovalev, A S; Vasil'eva, A N; Zyryanov, S M; Kurchikov, K; Proshina, O V; Voloshin, D G; Novikova, N N; Krishtab, M B; Baklanov, M R

2014-01-01

Modification of ultra-low-k films by extreme ultraviolet (EUV) and vacuum ultraviolet (VUV) emission with 13.5, 58.4, 106, 147 and 193 nm wavelengths and fluences up to 6 × 10 18  photons cm −2 is studied experimentally and theoretically to reveal the damage mechanism and the most ‘damaging’ spectral region. Organosilicate glass (OSG) and organic low-k films with k-values of 1.8–2.5 and porosity of 24–51% are used in these experiments. The Si–CH 3 bonds depletion is used as a criterion of VUV damage of OSG low-k films. It is shown that the low-k damage is described by two fundamental parameters: photoabsorption (PA) cross-section σ PA and effective quantum yield φ of Si–CH 3 photodissociation. The obtained σ PA and φ values demonstrate that the effect of wavelength is defined by light absorption spectra, which in OSG materials is similar to fused silica. This is the reason why VUV light in the range of ∼58–106 nm having the highest PA cross-sections causes strong Si–CH 3 depletion only in the top part of the films (∼50–100 nm). The deepest damage is observed after exposure to 147 nm VUV light since this emission is located at the edge of Si–O absorption, has the smallest PA cross-section and provides extensive Si–CH 3 depletion over the whole film thickness. The effective quantum yield slowly increases with the increasing porosity but starts to grow quickly when the porosity exceeds the critical threshold located close to a porosity of ∼50%. The high degree of pore interconnectivity of these films allows easy movement of the detached methyl radicals. The obtained results have a fundamental character and can be used for prediction of ULK material damage under VUV light with different wavelengths. (paper)

Materials processing with intense pulsed ion beams

International Nuclear Information System (INIS)

Rej, D.J.; Davis, H.A.; Olson, J.C.

1996-01-01

We review research investigating the application of intense pulsed ion beams (IPIBs) for the surface treatment and coating of materials. The short range (0.1-10 μm) and high-energy density (1-50 J/cm 2 ) of these short-pulsed (≤ 1 μs) beams (with ion currents I = 5 - 50 kA, and energies E = 100 - 1000 keV) make them ideal to flash-heat a target surface, similar to the more familiar pulsed laser processes. IPIB surface treatment induces rapid melt and solidification at up to 10 10 K/s to cause amorphous layer formation and the production of non-equilibrium microstructures. At higher energy density the target surface is vaporized, and the ablated vapor is condensed as coatings onto adjacent substrates or as nanophase powders. Progress towards the development of robust, high-repetition rate IPIB accelerators is presented along with economic estimates for the cost of ownership of this technology

High intensive short laser pulse interaction with submicron clusters media

International Nuclear Information System (INIS)

Faenov, A. Ya

2008-01-01

The interaction of short intense laser pulses with structured targets, such as clusters, exhibits unique features, stemming from the enhanced absorption of the incident laser light compared to solid targets. Due to the increased absorption, these targets are heated significantly, leading to enhanced emission of x rays in the keV range and generation of electrons and multiple charged ions with kinetic energies from tens of keV to tens of MeV. Possible applications of these targets can be an electron/ion source for a table top accelerator, a neutron source for a material damage study, or an x ray source for microscopy or lithography. The overview of recent results, obtained by the high intensive short laser pulse interaction with different submicron clusters media will be presented. High resolution K and L shell spectra of plasma generated by superintense laser irradiation of micron sized Ar, Kr and Xe clusters have been measured with intensity 10"17"-10"19"W/cm"2"and a pulse duration of 30-1000fs. It is found that hot electrons produced by high contrast laser pulses allow the isochoric heating of clusters and shift the ion balance toward the higher charge states, which enhances both the X ray line yield and the ion kinetic energy. Irradiation of clusters, produced from such gas mixture, by a fs Ti:Sa laser pulses allows to enhance the soft X ray radiation of Heβ(665.7eV)and Lyα(653.7eV)of Oxygen in 2-8 times compare with the case of using as targets pure CO"2"or N"2"O clusters and reach values 2.8x10"10"(∼3μJ)and 2.7x10"10"(∼2.9μJ)ph/(sr·pulse), respectively. Nanostructure conventional soft X ray images of 100nm thick Mo and Zr foils in a wide field of view (cm"2"scale)with high spatial resolution (700nm)are obtained using the LiF crystals as soft X ray imaging detectors. When the target used for the ion acceleration studies consists of solid density clusters embedded into the background gas, its irradiation by high intensity laser light makes the target

Efficacy of intense pulse light therapy and tripple combination cream versus intense pulse light therapy and tripple combination cream alone in epidermal melasma treatment

International Nuclear Information System (INIS)

Shakeeb, N.; Noor, S.M.; Paracha, M.M.; Ullah, G.

2018-01-01

Objective:To compare the efficacy of intense pulse light therapy (IPL) and triple combination cream (TCC) versus intense pulse light therapy and triple combination cream alone in epidermal melasma treatment, downgrading MASI score to more than 10. Study Design:Randomized controlled trial. Place and Duration of Study:Dermatology Department, Lady Reading Hospital, Peshawar, from August 2014 to January 2015. Methodology:Patients of 18-45 years were included in the study with Fitzpatrick skin type II-V. Sample of 96 patients was divided in to three groups of 32 each, through consecutive (non-probability) sampling method. Detailed history was taken, Woods Lamp Examination done, and melasma area and severity index (MASI) score was calculated. TCC had to be applied daily at night for two months by group A patients while group B was consigned for IPL therapy fortnightly, and those in group C were given both for two months. Efficacy was compared by recalculating MASI score at treatment end as well as at follow-up after 4 weeks, using Chi-square test with significance at p < 0.05. Results:Male and female patients were 10 (31.2%) and 22 (68.8%) in group A, 7 (21.9%) and 25 (78.1%) in group B, while in group C were 12 (37.5%) and 20 (62.5%). The average age was 28.70 +8.70 years. MASI score reduction was achieved in 22 (68.8%) patients in group A; whereas, in 20 (62.5%) and 30(93.8%) patients in group B and C, respectively. Efficacy-wise distribution was significant (p=0.009). Conclusion:Intense pulse light therapy and triple combination cream are more efficacious in epidermal melasma treatment than intense pulse light therapy and triple combination cream alone. (author)

Construction and temporal behaviour study of multi RLC intense light pulses for dermatological applications.

Science.gov (United States)

Hamoudi, Walid K; Ismail, Raid A; Shakir, Hussein A

2017-10-01

Driving a flash lamp in an intense pulsed light system requires a high-voltage DC power supply, capacitive energy storage and a flash lamp triggering unit. Single, double, triple and quadruple-mesh discharge and triggering circuits were constructed to provide intense light pulses of variable energy and time durations. The system was treated as [Formula: see text] circuit in some cases and [Formula: see text] circuit in others with a light pulse profile following the temporal behaviour of the exciting current pulse. Distributing the energy delivered to one lamp onto a number of LC meshes permitted longer current pulses, and consequently increased the light pulse length. Positive results were obtained when using the system to treat skin wrinkles.

Interaction of femtosecond X-ray pulses with periodical multilayer structures

International Nuclear Information System (INIS)

Ksenzov, Dmitry

2010-01-01

The VUV Free Electron Laser FLASH operates in soft X-ray range and produces high-intensive pulse trains with few tens femtoseconds duration. The transversely fully coherent beam will open new experiments in solid state physics which can not be studied with present radiation sources. The study of the time dependent response of the multilayer to the X-ray pulse can provide insights into the process of interaction of highly intense FEL radiation with matter. To test the influence of electron excitation on the optical properties of boron carbide, the refractive index of B 4 C was measured near B K-edge by energy-resolved photon-in-photon-out method probing a Bragg reflection from periodical multilayers. The measured data clearly show that the variation of the fine structure of the Kabsorption edges due to the chemical nature of the absorber element. The knowledge obtained from experiments with continuous radiation was used to design the respective experiments with pulse from the FEL. In my thesis, it is proposed that the geometrical setup, where the incident pulse arrives from the FEL under the angle close to the 1st order ML Bragg peak, provides the most valuable information. Preliminary simulation considering form factors of neutral and ionized boron showed that due to ionization, pronounced changes in the reflectivity curve are expected. The proposed scheme can be the powerful tool to study the various processes within the electronic subsystem of the FEL pulse interaction with matter. This type of investigations gives a deep understanding of the nature of the electronic excitation and the recombination at the femtosecond scale. (orig.)

Interaction of femtosecond X-ray pulses with periodical multilayer structures

Energy Technology Data Exchange (ETDEWEB)

Ksenzov, Dmitry

2010-07-01

The VUV Free Electron Laser FLASH operates in soft X-ray range and produces high-intensive pulse trains with few tens femtoseconds duration. The transversely fully coherent beam will open new experiments in solid state physics which can not be studied with present radiation sources. The study of the time dependent response of the multilayer to the X-ray pulse can provide insights into the process of interaction of highly intense FEL radiation with matter. To test the influence of electron excitation on the optical properties of boron carbide, the refractive index of B{sub 4}C was measured near B K-edge by energy-resolved photon-in-photon-out method probing a Bragg reflection from periodical multilayers. The measured data clearly show that the variation of the fine structure of the Kabsorption edges due to the chemical nature of the absorber element. The knowledge obtained from experiments with continuous radiation was used to design the respective experiments with pulse from the FEL. In my thesis, it is proposed that the geometrical setup, where the incident pulse arrives from the FEL under the angle close to the 1st order ML Bragg peak, provides the most valuable information. Preliminary simulation considering form factors of neutral and ionized boron showed that due to ionization, pronounced changes in the reflectivity curve are expected. The proposed scheme can be the powerful tool to study the various processes within the electronic subsystem of the FEL pulse interaction with matter. This type of investigations gives a deep understanding of the nature of the electronic excitation and the recombination at the femtosecond scale. (orig.)

National synchrotron light source user's manual: Guide to the VUV and x-ray beamlines: Third edition

International Nuclear Information System (INIS)

Gmuer, N.F.; Thomlinson, W.; White-DePace, S.

1989-01-01

This report contains information on the following topics: A Word on the Writing of Beamline Descriptions; Beamline Equipment Utilization for General Users; the Vacuum Ultraviolet (VUV) Storage Ring and Beamlines; VUV Beamline Descriptions--An Explanation; VUV Beamline Descriptions; X-Ray Storage Ring and Beamlines; X-Ray Beamline Descriptions--An Explanation; and X-Ray Beamline Descriptions

Utilizations of intense pulsed neutron source in radiochemistry and radiation chemistry

International Nuclear Information System (INIS)

Shiokawa, Takanobu; Yoshihara, Kenji; Kaji, Harumi; Kusaka, Yuzuru; Tabata, Yoneho.

1975-01-01

Intense pulsed neutron sources is expected to supply more useful and fundamental informations in radiochemistry and radiation chemistry. Short-lived intermediate species may be detected and the mechanisms of radiation induced reactions will be elucidated more precisely. Analytical application of pulsed neutrons is also very useful. (auth.)

Laser and intense pulsed light hair removal technologies

DEFF Research Database (Denmark)

Haedersdal, M; Beerwerth, F; Nash, J F

2011-01-01

Light-based hair removal (LHR) is one of the fastest growing, nonsurgical aesthetic cosmetic procedures in the United States and Europe. A variety of light sources including lasers, e.g. alexandrite laser (755 nm), pulsed diode lasers (800, 810 nm), Nd:YAG laser (1064 nm) and broad-spectrum intense...

New perspectives for organic chemistry and biochemistry in VUV: reaction kinetics, chirality and thermochemistry. Summaries

International Nuclear Information System (INIS)

Nahon, Laurent; Field, David; Gerber, Thomas; Knopp, Gregor; Beaud, Paul; Radi, Peter; Tulej, Marek; Dedonder-Lardeux, Claude; Jung, J.M.; Laprevote, Olivier; Thissen, Roland; Le Barbu, K.; Lahmani, F.; Zehnacker, A.; Maurizot, Jean Claude; Barbier, Bernard; Kagan, Henri B.

2001-10-01

The aim of this workshop was to examine the conditions of use of VUV for the study of complex molecular systems, and notably bio-molecules, a domain which is greatly expanding. The conclusions of this one-day workshop should allow to define new fields of utilization of the synchrotron radiation in VUV, to precise certain performances that are needed for the transferred line, to establish the complementarities with other VUV sources (lasers, free electron lasers, lamps) and to determine the eventual need for a second low energy light line at SOLEIL. The titles of the various abstract papers presented are (two papers are in English, the rest is in French): SU5, a high resolution and variable polarization VUV line that should be transferred at SOLEIL; Interstellar organic chemistry (in English); Application of spectroscopic techniques in the VUV to combustion relevant molecules (in English); Gaseous phase reaction kinetics (bi-molecular reactions in collision and in aggregates); Liquids of biological interest (excitation and relaxation close to the ionization threshold); Successes and impediments in protein mass spectrometry (the potential contribution of VUV synchrotron radiation); Stereo-specific effects; Complexes between chiral molecules; circular dichroism of biomolecules; Exobiology; asymmetric synthesis (principles and recent results)

Excitation of random intense single-cycle light-pulse chains in optical fiber

International Nuclear Information System (INIS)

Ding, Y C; Zhang, F L; Gao, J B; Chen, Z Y; Lin, C Y; Yu, M Y

2014-01-01

Excitation of intense periodic single-cycle light pulses in a stochastic background arising from continuous wave stimulated Brillouin scattering (SBS) in a long optical fiber with weak optical feedback is found experimentally and modeled theoretically. Such intense light-pulse chains occur randomly and the optical feedback is a requirement for their excitation. The probability of these forms, among the large number of experimental output signals with identifiable waveforms, appearing is only about 3%, with the remainder exhibiting regular SBS characteristics. It is also found that pulses with low period numbers appear more frequently and the probability distribution for their occurrence in terms of the pulse power is roughly L-shaped, like that for rogue waves. The results from a three-wave-coupling model for SBS including feedback phase control agree well qualitatively with the observed phenomena. (paper)

Enhancement of High-Intensity Focused Ultrasound Heating by Short-Pulse Generated Cavitation

Directory of Open Access Journals (Sweden)

Shin Yoshizawa

2017-03-01

Full Text Available A target tissue can be thermally coagulated in high-intensity focused ultrasound (HIFU treatment noninvasively. HIFU thermal treatments have been clinically applied to various solid tumors. One of the problems in HIFU treatments is a long treatment time. Acoustically driven microbubbles can accelerate the ultrasonic heating, resulting in the significant reduction of the treatment time. In this paper, a method named “trigger HIFU exposure” which employs cavitation microbubbles is introduced and its results are reviewed. A trigger HIFU sequence consists of high-intensity short pulses followed by moderate-intensity long bursts. Cavitation bubbles induced in a multiple focal regions by rapidly scanning the focus of high-intensity pulses enhanced the temperature increase significantly and produced a large coagulation region with high efficiency.

Progress toward a microsecond duration, repetitively pulsed, intense- ion beam

International Nuclear Information System (INIS)

Davis, H.A.; Olson, J.C.; Reass, W.A.; Coates, D.M.; Hunt, J.W.; Schleinitz, H.M.; Greenly, J.B.

1996-01-01

A number of intense ion beams applications are emerging requiring repetitive high-average-power beams. These applications include ablative deposition of thin films, rapid melt and resolidification for surface property enhancement, advanced diagnostic neutral beams for the next generation of Tokamaks, and intense pulsed-neutron sources. We are developing a 200-250 keV, 15 kA, 1 μs duration, 1-30 Hz intense ion beam accelerator to address these applications

Demonstration of resonant photopumping of Mo VII by Mo XII for a VUV laser near 600 Angstrom

International Nuclear Information System (INIS)

Ilcisin, K.J.; Aumayr, F.; Schwob, J.L.; Suckewer, S.

1993-09-01

We present data of experiments on the resonant photopumping of Mo VII by Mo XII as a method of generating a coherent VUV source near 600 angstrom. The experiment is based on a scheme proposed by Feldman and Reader in which the 4p 6 -- 4p 5 6s transition in Mo VII in resonantly photopumped by the 5s 2 S 1/2 -- 4p 2 P 1/2 transition in Mo XII. Results of the laser produced plasma experiments show the successful enhancement of the population of the Mo VII 4p 5 6s upper lasing level when pumped by an adjacent Mo VII plasma. No enhancement was seen in a control experiment where the Mo VII plasma was pumped by a Zr X plasma. Improvements of the intensity of the Mo XII pump source, achieved using an additional pump laser, lead to the generation of a population inversion for the VUV transition

Carcinogenesis related to intense pulsed light and UV exposure

DEFF Research Database (Denmark)

Hedelund, L; Lerche, C; Wulf, H C

2006-01-01

This study examines whether intense pulsed light (IPL) treatment has a carcinogenic potential itself or may influence ultraviolet (UV)-induced carcinogenesis. Secondly, it evaluates whether UV exposure may influence IPL-induced side effects. Hairless, lightly pigmented mice (n=144) received three...

Real-time monitoring of trace-level VOCs by an ultrasensitive compact lamp-based VUV photoionization mass spectrometer

Science.gov (United States)

Sun, W. Q.; Shu, J. N.; Zhang, P.; Li, Z.; Li, N. N.; Liang, M.; Yang, B.

2015-06-01

In this study, we report on the development of a compact lamp-based vacuum ultraviolet (VUV) photoionization mass spectrometer (PIMS; hereafter referred to as VUV-PIMS) in our laboratory; it is composed of a radio frequency-powered VUV lamp, a VUV photoionizer, an ion-immigration region, and a reflection time-of-flight mass spectrometer. By utilizing the novel photoionizer consisting of a photoionization cavity and a VUV light baffle, extremely low background noise was obtained. An ultrasensitive detection limit (2σ) of 3 pptv was achieved for benzene after an acquisition time of 10 s. To examine its potential for application in real-time sample monitoring, the developed VUV-PIMS was employed for the continuous measurement of urban air for six days in Beijing, China. Strong signals of trace-level volatile organic compounds such as benzene and its alkylated derivatives were observed in the mass spectra. These initial experimental results reveal that the instrument can be used for the online monitoring of trace-level species in the atmosphere.

Progress toward a microsecond duration, repetitively pulsed, intense-ion beam

Energy Technology Data Exchange (ETDEWEB)

Davis, H A; Olson, J C; Reass, W A [Los Alamos National Lab., NM (United States); Coates, D M; Hunt, J W; Schleinitz, H M [DuPont Central Research and Development, Wilmington, DE (United States); Lovberg, R H [Univ. of California, San Diego, CA (United States); Greenly, J B [Cornell Univ., Ithaca, NY (United States). Lab. of Plasma Studies

1997-12-31

A number of intense ion beams applications are emerging requiring repetitive high-average-power beams. These applications include ablative deposition of thin films, rapid melt and resolidification for surface property enhancement, advanced diagnostic neutral beams for the next generation of Tokamaks, and intense pulsed-neutron sources. A 200-250 keV, 15 kA, 1 {mu}s duration, 1-30 Hz intense ion beam accelerator is being developed to address these applications. (author). 4 figs., 7 refs.

Coulomb explosion of H2 induced by a sub-10 fs intense laser pulse

International Nuclear Information System (INIS)

Saugout, S.

2006-12-01

This work presents an experimental and theoretical study of the interaction of H2 with an intense sub-10 fs-laser pulse. The ejection of the two electrons of the molecule by the laser pulse leads to the fragmentation of the physical sys em in two protons. This process is called Coulomb Explosion. The electronic and nuclear dynamics can be analyzed by measuring the kinetic energy spectra as a function of different laser parameters. This dynamics is also analyzed through a non-perturbative, double active electron theoretical model, based on the resolution of the time dependent Schroedinger equation. In this model, the internuclear distance is treated as a quantum variable. The experimental and theoretical results enlight the translation of the kinetic energy spectra towards a higher energy when the pulse duration decreases. Experimentally, laser pulses from 40 to 10 fs were used and down to 1 fs using theoretical simulations. This study shows that, for laser pulses shorter than 4 fs, the carrier envelope phase becomes a crucial parameter. Furthermore, the molecular dynamics of H2 in intense laser field is sensitive to the peak intensity of the pulse. The experimental and theoretical results show that, as the intensity increases, the kinetic energy spectra are centered around a higher energy. In addition, the presence of two double ionization regimes is theoretically demonstrated for a pulse duration of 4 fs. The H 2 molecule is also sensitive to the temporal shape of the laser pulse. This sensitivity allows for the detection of pre- or post-pulses by measuring the experimental kinetic energy spectra. Finally, the different double ionization processes are studied. The results show that the electron rescattering influences the femtosecond nuclear dynamics. (author)

Self-organization of high intensity laser pulses propagating in gases

International Nuclear Information System (INIS)

Koga, James

2001-01-01

In recent years the development of high intensity short pulse lasers has opened up wide fields of science which had previously been difficult to study. Recent experiments of short pulse lasers propagating in air have shown that these laser pulses can propagate over very long distances (up to 12 km) with little or no distortion of the pulse. Here we present a model of this propagation using a modified version of the self-organized criticality model developed for sandpiles by Bak, Tang, and Weisenfeld. The additions to the sandpile model include the formation of plasma which acts as a threshold diffusion term and self-focusing by the nonlinear index of refraction which acts as a continuous inverse diffusion. Results of this simple model indicate that a strongly self-focusing laser pulse shows self-organized critical behavior. (author)

Modification of solid surface by intense pulsed light-ion and metal-ion beams

Science.gov (United States)

Nakagawa, Y.; Ariyoshi, T.; Hanjo, H.; Tsutsumi, S.; Fujii, Y.; Itami, M.; Okamoto, A.; Ogawa, S.; Hamada, T.; Fukumaru, F.

1989-03-01

Metal surfaces of Al, stainless-steel and Ti were bombarded with focused intense pulsed proton and carbon ion beams (energy ˜ 80 keV, current density ≲ 1000 A/cm 2, pulse width ˜ 300 ns). Thin titanium carbide layers were produced by carbon-ion irradiation on the titanium surface. The observed molten surface structures and recrystallized layer (20 μm depth) indicated that the surfaces reached high temperatures as a result of the irradiation. The implantation of intense pulsed metal ion beams (Al +, ˜ 20 A/cm 2) with simultaneous deposition of anode metal vapor on Ti and Fe made a mixed layer of AlTi and AlFe of about 0.5 μm depth. Ti and B multilayered films evaporated on glass substrates were irradiated by intense pulsed proton beams of relatively lower current density (10-200 A/cm 2). Ti films containing B atoms above 10 at.% were obtained. When the current density was about 200 A/cm 2 diffraction peaks of TiB 2 appeared.

Gas-filled cell as a narrow bandwidth bandpass filter in the VUV wavelength range

Energy Technology Data Exchange (ETDEWEB)

Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2011-04-15

We propose a method for spectrally filtering radiation in the VUV wavelength range by means of a monochromator constituted by a cell filled with a resonantly absorbing rare gas. Around particular wavelengths, the gas exhibits narrow-bandwidth absorbing resonances following the Fano profile. In particular, within the photon energy range 60 eV-65 eV, the correlation index of the Fano profiles for the photoionization spectra in Helium is equal to unity, meaning that the minimum of the cross-section is exactly zero. For sufficiently large column density in the gas cell, the spectrum of the incoming radiation will be attenuated by the background cross-section of many orders of magnitude, except for those wavelengths close to the point where the cross-section is zero. Remarkable advantages of a gas monochromator based on this principle are simplicity, efficiency and narrow-bandwidth. A gas monochromator installed in the experimental hall of a VUV SASE FEL facility would enable the delivery of a single-mode VUV laser beam. The design is identical to that of already existing gas attenuator systems for VUV or X-ray FELs. We present feasibility study and exemplifications for the FLASH facility in the VUV regime. (orig.)

VUV emission spectroscopy diagnostics of a 14 GHz ECR negative hydrogen ion source

Energy Technology Data Exchange (ETDEWEB)

Tamura, R., E-mail: duo0364@mail4.doshisha.ac.jp; Ichikawa, T.; Kasuya, T.; Wada, M. [Graduate School of Science and Engineering, Doshisha University, Kyotanabe, Kyoto 610-0394 (Japan); Nishiura, M. [Graduate School of Frontier Sciences The University of Tokyo, Kashiwara, Chiba 277-8561 (Japan); Shimozuma, T. [National lnstitute for Fusion Science, Toki, Gifu 509-5292 (Japan)

2015-04-08

Vacuum Ultra Violet(VUV) emission from a 4 cm diameter 2 cm long compact ion source excited by 14 GHz microwave has been investigated. Intensity ratio of band spectrum emission near Ly-α to Ly-α line spectrum is determined from the measured spectrum. which shows preferential excitation of molecules near the entrance of microwave input power. The ratio does not depend strongly upon pressure nor the input microwave power when the intensity is integrated over the volume of the plasma. The spatial distribution of the spectrum intensity ratio exhibits concentrations near microwave inlet and the opposite side where the microwave matching structure is located. The ratio at these peripheral regions is about two times as high as that of the central region. The ratio increased in proportion to the ion source pressure up to about 3.0 Pa, indicating efficient production of high energy electrons by ECR up to this pressure.

Effect of high-hydrostatic pressure and moderate-intensity pulsed electric field on plum.

Science.gov (United States)

García-Parra, J; González-Cebrino, F; Delgado-Adámez, J; Cava, R; Martín-Belloso, O; Élez-Martínez, P; Ramírez, R

2018-03-01

Moderate intensity pulse electric fields were applied in plum with the aim to increase bioactive compounds content of the fruit, while high-hydrostatic pressure was applied to preserve the purées. High-hydrostatic pressure treatment was compared with an equivalent thermal treatment. The addition of ascorbic acid during purée manufacture was also evaluated. The main objective of this study was to assess the effects on microorganisms, polyphenoloxidase, color and bioactive compounds of high-hydrostatic pressure, or thermal-processed plum purées made of moderate intensity pulse electric field-treated or no-moderate intensity pulse electric field-treated plums, after processing during storage. The application of moderate intensity pulse electric field to plums slightly increased the levels of anthocyanins and the antioxidant activity of purées. The application of Hydrostatic-high pressure (HHP) increased the levels of bioactive compounds in purées, while the thermal treatment preserved better the color during storage. The addition of ascorbic acid during the manufacture of plum purée was an important factor for the final quality of purées. The color and the bioactive compounds content were better preserved in purées with ascorbic acid. The no inactivation of polyphenoloxidase enzyme with treatments applied in this study affected the stability purées. Probably more intense treatments conditions (high-hydrostatic pressure and thermal treatment) would be necessary to reach better quality and shelf life during storage.

Strategy for Realizing High-Precision VUV Spectro-Polarimeter

Science.gov (United States)

Ishikawa, R.; Narukage, N.; Kubo, M.; Ishikawa, S.; Kano, R.; Tsuneta, S.

2014-12-01

Spectro-polarimetric observations in the vacuum ultraviolet (VUV) range are currently the only means to measure magnetic fields in the upper chromosphere and transition region of the solar atmosphere. The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) aims to measure linear polarization at the hydrogen Lyman- α line (121.6 nm). This measurement requires a polarization sensitivity better than 0.1 %, which is unprecedented in the VUV range. We here present a strategy with which to realize such high-precision spectro-polarimetry. This involves the optimization of instrument design, testing of optical components, extensive analyses of polarization errors, polarization calibration of the instrument, and calibration with onboard data. We expect that this strategy will aid the development of other advanced high-precision polarimeters in the UV as well as in other wavelength ranges.

High Intensity, Pulsed, D-D Neutron Generator

International Nuclear Information System (INIS)

Williams, D.L.; Vainionpaa, J.H.; Jones, G.; Piestrup, M.A.; Gary, C.K.; Harris, J.L.; Fuller, M.J.; Cremer, J.T.; Ludewigt, Bernhard A.; Kwan, J.W.; Reijonen, J.; Leung, K.-N.; Gough, R.A.

2008-01-01

Single ion-beam RF-plasma neutron generators are presented as a laboratory source of intense neutrons. The continuous and pulsed operations of such a neutron generator using the deuterium-deuterium fusion reaction are reported. The neutron beam can be pulsed by switching the RF plasma and/or a gate electrode. These generators are actively vacuum pumped so that a continuous supply of deuterium gas is present for the production of ions and neutrons. This contributes to the generator's long life. These single-beam generators are capable of producing up to 1E10 n/s. Previously, Adelphi and LBNL have demonstrated these generators applications in fast neutron radiography, Prompt Gamma Neutron Activation Analysis (PGNAA) and Neutron Activation Analysis (NAA). Together with an inexpensive compact moderator, these high-output neutron generators extend useful applications to home laboratory operations.

Simulation of intense short-pulse laser-plasma interaction

International Nuclear Information System (INIS)

Yamagiwa, Mitsuru

2000-01-01

We have completed the massive parallelization of a 2-dimensional giga-particle code and have achieved a 530-fold acceleration rate with 512 processing elements (PE's). Using this we have implemented a simulation of the interaction of a solid thin film and a high intensity laser and have discovered a phenomenon in which high quality short pulses from the far ultraviolet to soft X-rays are generated at the back surface of the thin layer. We have also introduced the atomic process database code (Hullac) and have the possibility for high precision simulations of X-ray laser radiation. With respect to laser acceleration we have the possibility to quantitatively evaluate relativistic self-focusing assumed to occur in higher intensity fields. Ion acceleration from a solid target and an underdense plasma irradiated by an intense and an ultra intense laser, respectively, has also been studied by particle-in-cell (PIC) simulations. (author)

Duke storage rink UV/VUV FEL: Status and prospects

Energy Technology Data Exchange (ETDEWEB)

Litvinenko, V.N.; Burnham, B.; Madey, J.M.J. [Duke Univ., Durham, NC (United States)] [and others

1995-12-31

The 1 GeV Duke storage ring was successfully commissioned with parameters exceeding initial specification. The OK-4 FEL has arrived at the Duke FEL laboratory from the Novosibirsk Institute of Nuclear Physics. The OK-4 installation and commissioning is in progress. In this paper we describe the up-to-date status of the Duke storage ring and the OK-4 FEL. The projected performance of the OK-4 UV/VUV FEL is presented based on the electron beam parameters achieved. Initial plans to operate the OK-4 UV/VUV FEL at the Duke 1 GeV storage ring are outlined. Future plans and prospects of both the OK-4 FEL and the Duke storage ring are discussed.

Photoionization of atoms and molecules by intense EUV-FEL pulses and FEL seeded by high-order harmonic of ultrashort laser pulses

International Nuclear Information System (INIS)

Iwasaki, Atsushi; Owada, Shigeki; Yamanouchi, Kaoru; Sato, Takahiro; Nagasono, Mitsuru; Yabashi, Makina; Ishikawa, Tetsuya; Togashi, Tadashi; Takahashi, Eiji J.; Midorikawa, Katsumi; Aoyama, Makoto; Yamakawa, Koichi; Kannari, Fumihiko; Yagishita, Akira

2012-01-01

The advantages of SPring-8 Compact SASE Source as a light source for spectroscopic measurements in the extreme ultraviolet (EUV) wavelength region are introduced by referring to our recent study of non-linear photoionization processes of He, in which the absolute two-photon ionization cross sections of He at four different wavelengths in the 54 - 62 nm region were determined using intense pulses of the free-election laser (FEL). In addition, our recent effort to generate intense full-coherent EUV light pulses are introduced, in which significant amplification of the 13th harmonic of ultrashort laser pulses at 800 nm was achieved by FEL seeded with the 13th harmonic. (author)

Generation of high intensity rf pulses in the ionosphere by means of in situ compression

International Nuclear Information System (INIS)

Cowley, S.C.; Perkins, F.W.; Valeo, E.J.

1993-04-01

We demonstrate, using a simple model, that high intensity pulses can be generated from a frequency-chirped modifier of much lower intensity by making use of the dispersive properties of the ionosphere. We show that a frequency-chirped pulse can be constructed so that its various components overtake each other at a prescribed height, resulting in large (up to one hundred times) transient intensity enhancements as compared to those achievable from a steady modifier operating at the same power. We examine briefly one possible application: the enhancement of plasma wave amplitudes which occurs as a result of the interaction of such a compressed pulse with pre-generated turbulence

VUV light induced valence degeneration in Sm over-layer on HOPG

International Nuclear Information System (INIS)

Kutluk, G; Nakatake, M; Arita, M; Namatame, H; Taniguchi, M; Ishitobi, Y; Sumida, H

2013-01-01

Systematic investigation of the influence of vacuum ultraviolet (VUV) irradiation on the valence degeneration in a Sm over-layer on a HOPG substrate was performed using in-situ photoemission spectroscopy (XPS, UPS, and ARPES) for the Sm coverage regime of 0.05-3.6 Å. This investigation confirmed that VUV irradiation-induced degeneration of divalent Sm exerts a more profound effect than Sm contamination during photoemission spectroscopy even under UHV. We found that the charge transfer occurs mainly from divalent Sm to the HOPG surface.

Enhancement of peak intensity in a filament core with spatiotemporally focused femtosecond laser pulses

Energy Technology Data Exchange (ETDEWEB)

Zeng Bin; Chu Wei; Li Guihua; Zhang Haisu; Ni Jielei [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Graduate School of Chinese Academy of Sciences, Beijing 100080 (China); Gao Hui; Liu Weiwei [Institute of Modern Optics, Nankai University, Tianjin, 300071 (China); Yao Jinping; Cheng Ya; Xu Zhizhan [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Chin, See Leang [Center for Optics, Photonics and Laser (COPL) and Department of Physics, Engineering Physics and Optics, Universite Laval, Quebec City, QC, G1V 0A6 (Canada)

2011-12-15

We demonstrate that the peak intensity in the filament core, which is inherently limited by the intensity clamping effect during femtosecond laser filamentation, can be significantly enhanced using spatiotemporally focused femtosecond laser pulses. In addition, the filament length obtained by spatiotemporally focused femtosecond laser pulses is {approx}25 times shorter than that obtained by a conventional focusing scheme, resulting in improved high spatial resolution.

Preliminary research results for parameter diagnostics of intense pulsed ion beams

International Nuclear Information System (INIS)

Yang Hailiang; Qiu Aici; Sun Jianfeng; He Xiaoping; Tang Junping; Wang Haiyang; Li Jingya; Ren Shuqing; Huang Jianjun; Zhang Jiasheng; Peng Jianchang; Ouyang Xiaoping; Zhang Guoguang; Li Hongyu

2004-01-01

The preliminary experimental results for parameter diagnostics of intense pulsed ion beams from the FLASH II accelerator were reported. The ion number of an intense pulsed ion beam were experimentally determined by monitoring delayed radioactivity from protons induced nuclear reactions in a 12 C target. The prompt γ-rays and diode Bremsstrahlung X-rays were measured with PIN semi-conductor detector and a ST401 plastic scintillator detector. The Bremsstrahlung distribution outside of the drift tube was detected with a thermoluminescent detector and the shielding design was also determined. The current densities of beam were measured with biased ion collector array. The ion beams were also recorded with a CR-39 detector. (author)

Brighter H- source for the intense pulsed neutron source accelerator system

International Nuclear Information System (INIS)

Stipp, V.; DeWitt, A.; Madsen, J.

1983-01-01

Further increases in the beam intensity of the Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory required the replacement of the H - source with a higher current source. A magnetron ion source of Fermi National Accelerator Laboratory (FNAL) design was adapted with a grooved cathode to provide a stable 40 to 50 mA of beam operating at 30 Hz for up to a 90 μs pulse duration. Problems of space charge blowup due to the lack of neutralization of the H - beam were solved by injecting additional gs into the 20 keV transport system. The source has recently been installed in the machine and the available input to the accelerator has more than doubled

The role of lasers and intense pulsed light technology in dermatology

Science.gov (United States)

Husain, Zain; Alster, Tina S

2016-01-01

The role of light-based technologies in dermatology has expanded dramatically in recent years. Lasers and intense pulsed light have been used to safely and effectively treat a diverse array of cutaneous conditions, including vascular and pigmented lesions, tattoos, scars, and undesired hair, while also providing extensive therapeutic options for cosmetic rejuvenation and other dermatologic conditions. Dermatologic laser procedures are becoming increasingly popular worldwide, and demand for them has fueled new innovations and clinical applications. These systems continue to evolve and provide enhanced therapeutic outcomes with improved safety profiles. This review highlights the important roles and varied clinical applications that lasers and intense pulsed light play in the dermatologic practice. PMID:26893574

Laser plasma as a source of intense attosecond pulses via high-order harmonic generation

International Nuclear Information System (INIS)

Ozaki, T.

2013-01-01

The incredible progress in ultrafast laser technology and Ti:sapphire lasers have lead to many important applications, one of them being high-order harmonic generation (HHG). HHG is a source of coherent extreme ultraviolet (XUV) radiation, which has opened new frontiers in science by extending nonlinear optics and time-resolved spectroscopy to the XUV region, and pushing ultrafast science to the attosecond domain. Progress in attosecond science has revealed many new phenomena that have not been seen with femtosecond pulses. Clearly, the next frontier is to study nonlinear effects at the attosecond timescale and in the XUV. However, a problem with present-day attosecond pulses is that they are just too weak to induce measurable nonlinearities, which severely limits the application of this source. While HHG from solid targets has shown promise for higher conversion efficiency, there is no experiment so far that demonstrates isolated attosecond pulse generation. The generation of isolated, several 100-as pulses with few-µJ energy will enable us to enter a completely new phase in attoscience. In past works, we have demonstrated that high-order harmonics from lowly ionized plasma is a highly efficient method to generate coherent XUV pulses. For example, indium plasma has been shown to generate intense 13th harmonic of the Ti:sapphire laser, with conversion efficiency of 10-4. However, the quasi-monochromatic nature of indium harmonics would make it difficult to generate attosecond pulses. We have also demonstrated that one could increase the harmonic yield by using nanoparticle targets. Specifically, we showed that by using indium oxide nanoparticles or C60 film, we could obtain intense harmonics between wavelengths of 50 to 90 nm. The energy in each of these harmonic orders was measured to be a few µJ, which is sufficient for many applications. However, the problem of using nanoparticle or film targets is the rapid decrease in the harmonic intensity, due to the rapid

Temporary acceleration of electrons while inside an intense electromagnetic pulse

Directory of Open Access Journals (Sweden)

Kirk T. McDonald

1999-12-01

Full Text Available A free electron can temporarily gain a very significant amount of energy if it is overrun by an intense electromagnetic wave. In principle, this process would permit large enhancements in the center-of-mass energy of electron-electron, electron-positron, and electron-photon interactions if these take place in the presence of an intense laser beam. Practical considerations severely limit the utility of this concept for contemporary lasers incident on relativistic electrons. A more accessible laboratory phenomenon is electron-positron production via an intense laser beam incident on a gas. Intense electromagnetic pulses of astrophysical origin can lead to very energetic photons via bremsstrahlung of temporarily accelerated electrons.

Photoluminescence of phosphors for PDP with VUV excitation

International Nuclear Information System (INIS)

Lu, H.-C.; Chen, H.-K.; Tseng, T.-Y.; Kuo, W.-L.; Alam, M.S.; Cheng, B.-M.

2005-01-01

In a plasma display panel (PDP) He-Xe or Ne-Xe gaseous mixtures are subjected to electric discharge between two glass panels, so to generate VUV light. Red, green and blue phosphors absorb this VUV radiation and re-radiate the energy as visible light to produce the colors that appear on the screen. The phosphor plays an important role in the working of a PDP. To improve the efficiency of phosphors, we have established a photoluminescence end station coupled to the beam line of a synchrotron to study the luminescence of PDP phosphors. This luminescence is analyzed with a 0.32 m monochromator having maximum resolution 0.04 nm, and is monitored with a photomultiplier tube operated in a photon-counting mode. Preliminary data demonstrate the powerful performance of this end-station for studying PDP phosphors

ASPUN: design for an Argonne super-intense pulsed neutron source

International Nuclear Information System (INIS)

Khoe, T.K.; Kustom, R.L.

1983-01-01

Argonne pioneered the pulsed spallation neutron source with the ZING-P and IPNS-I concepts. IPNS-I is now a reliable and actively used source for pulsed spallation neutrons. The accelerator is a 500-MeV, 8 to 9 μa, 30-Hz rapid-cycling proton synchrotron. Other proton spallation sources are now in operation or in construction. These include KENS-I at the National Laboratory for High Energy Physics in Japan, the WNR/PSR at Los Alamos National Laboratory in the USA, and the SNS at the Rutherford Appleton Laboratory in England. Newer and bolder concepts are being developed for more-intense pulsed spallation neutron sources. These include SNQ at the KFA Laboratory in Juelich, Germany, ASTOR at the Swiss Institute for Nuclear Physics in Switzerland, and ASPUN, the Argonne concept. ASPUN is based on the Fixed-Field Alternating Gradient concept. The design goal is to provide a time-averaged beam of 3.5 ma at 1100 MeV on a spallation target in intense bursts, 100 to 200 nanoseconds long, at a repetition rate of no more than 60 to 85 Hz

Chemical evolution of Titan’s aerosol analogues under VUV irradiation

Science.gov (United States)

Carrasco, Nathalie; Gavilan, Lisseth; Tigrine, Sarah; Vettier, Ludovic; Nahon, Laurent; Pernot, Pascal

2017-10-01

Since the Cassini-CAPS measurements, organic aerosols are known to be present and formed at high altitudes in the diluted and partially ionized medium that is Titan’s ionosphere [1].After production in the ionosphere, Titan’s aerosols evolve through microphysics during their sedimentation down to Titan’s surface [2]. Starting with a few nanomers size in the upper atmosphere, they reach a fractal structure of a few hundreds nanometers close to the surface [3]. During sedimentation, aerosols are also submitted to solar irradiation. As laboratory analogs of Titan’s atmospheric aerosols (tholins) show a strong UV absorption [4], we suspect that VUV irradiation could also induce a chemical evolution of Titan’s aerosols during their descent in Titan’s atmosphere.The aim of this work ist to simulate the irradiation process occuring on the aerosols in Titan’s atmosphere and to address whether this irradiation impacts the chemical composition of the organic solids. First aerosol analogues were produced in a N2-CH4 plasma discharge as thin organic films of a few hundreds of nanometers thick [5]. Then those were irradiated at Lyman-α wavelength, the strongest VUV line in the solar spectrum, with a high photon flux on a synchrotron VUV beamline. We will present and discuss the significant chemical evolutions observed on the analogues after VUV irradiation by mid-IR absorption spectroscopy.[1] Waite et al. (2009) Science , 316, p. 870[2] Lavvas et al. (2011) Astrophysical Journal, 728:80[3] Tomasko et al. (2008) Planetary and Space Science, 56, p. 669[4] Mahjoub et al. (2012) Icarus 221, P. 670[5] Carrasco et al. (2016) Planetary and Space Science, 128, p. 52

Double discharges in unipolar-pulsed dielectric barrier discharge xenon excimer lamps

International Nuclear Information System (INIS)

Liu Shuhai; Neiger, Manfred

2003-01-01

Excitation of dielectric barrier discharge xenon excimer lamps by unipolar short square pulses is studied in this paper. Two discharges with different polarity are excited by each voltage pulse (double discharge phenomenon). The primary discharge occurs at the top or at the rising flank of the applied unipolar square pulse, which is directly energized by the external circuit. The secondary discharge with the reversed polarity occurs at the falling flank or shortly after the falling flank end (zero external voltage) depending on the pulse width, which is energized by the energy stored by memory charges deposited by the primary discharge. Fast-speed ICCD imaging shows the primary discharge has a conic discharge appearance with a channel broadening on the anode side. This channel broadening increases with increasing the pulse top level. Only the anode-side surface discharge is observed in the primary discharge. The surface discharge on the cathode side which is present in bipolar sine voltage excitation is not observed. On the contrary, the secondary discharge has only the cathode-side surface discharge. The surface discharge on the anode side is not observed. The secondary discharge is much more diffuse than the primary discharge. Time-resolved emission measurement of double discharges show the secondary discharge emits more VUV xenon excimer radiation but less infrared (IR) xenon atomic emission than the primary discharge. It was found that the IR xenon atomic emission from the secondary discharge can be reduced by shortening the pulse width. The energy efficiency of unipolar-pulsed xenon excimer lamps (the overall energy efficiency of double discharges) is much higher than that obtained under bipolar sine wave excitation. The output VUV spectrum under unipolar pulse excitation is found to be identical to that under sine wave excitation and independent of injected electric power

UV-VUV laser induced phenomena in SiO2 glass

International Nuclear Information System (INIS)

Kajihara, Koichi; Ikuta, Yoshiaki; Oto, Masanori; Hirano, Masahiro; Skuja, Linards; Hosono, Hideo

2004-01-01

Creation and annihilation of point defects were studied for SiO 2 glass exposed to ultraviolet (UV) and vacuum UV (VUV) lights to improve transparency and radiation toughness of SiO 2 glass to UV-VUV laser light. Topologically disordered structure of SiO 2 glass featured by the distribution of Si-O-Si angle is a critical factor degrading transmittance near the fundamental absorption edge. Doping with terminal functional groups enhances the structural relaxation and reduces the number of strained Si-O-Si bonds by breaking up the glass network without creating the color centers. Transmittance and laser toughness of SiO 2 glass for F 2 laser is greatly improved in fluorine-doped SiO 2 glass, often referred as 'modified silica glass'. Interstitial hydrogenous species are mobile and reactive at ambient temperature, and play an important role in photochemical reactions induced by exposure to UV-VUV laser light. They terminate the dangling-bond type color centers, while enhancing the formation of the oxygen vacancies. These findings are utilized to develop a deep-UV optical fiber transmitting ArF laser photons with low radiation damage

Low-intensity pulsed ultrasound affects human articular chondrocytes in vitro

NARCIS (Netherlands)

Korstjens, C.M.; van der Rijt, R.H.H.; Albers, G.H.; Semeins, C.M.; Klein-Nulend, J.

2008-01-01

We investigated whether low-intensity pulsed ultrasound (LIPUS) stimulates chondrocyte proliferation and matrix production in explants of human articular cartilage obtained from donors suffering from unicompartimental osteoarthritis of the knee, as well as in isolated human chondrocytes in vitro.

Two-color photoionization and photoelectron studies by combining infrared and vacuum ultraviolet

International Nuclear Information System (INIS)

Ng, C.Y.

2005-01-01

Recent developments of two-color infrared (IR)-vacuum ultraviolet (VUV) and VUV-IR photoionization and photoelectron detection schemes for spectroscopic studies are described. By preparing molecules in selected rovibrational states by IR excitation prior to VUV-photoionization, state-selected and state-to-state photoionization cross sections can be obtained by IR-VUV-photoionization efficiency (IR-VUV-PIE) and IR-VUV-pulsed field ionization-photoelectron (IR-VUV-PFI-PE) measurements, respectively. Rotationally resolved autoionizing Rydberg states converging to excited ionic states, which cannot be observed by single-photon VUV-PIE measurements, can be examined by the IR-VUV-PIE scheme. By monitoring the photoion and the PFI-PE intensities at a fixed VUV energy as a function of IR frequency, the respective IR photoion and IR absorption spectra of the corresponding neutral molecule can be measured. Two-color VUV-IR photo-induced Rydberg ionization (PIRI) experiment, in which high-n Rydberg states are prepared by VUV-photoexcitation followed by IR-induced autoionization, has also been demonstrated. Since the IR-VUV-PIE, IR-VUV-PFI-PE, and VUV-IR-PIRI methods do not require the existence of a bound intermediate electronic state in the UV and are generally applicable to all molecules, the development of these two-color photoionization and photoelectron schemes is expected to significantly enhance the scope of VUV spectroscopy and chemistry

Modeling of intense pulsed ion beam heated masked targets for extreme materials characterization

Science.gov (United States)

Barnard, John J.; Schenkel, Thomas

2017-11-01

Intense, pulsed ion beams locally heat materials and deliver dense electronic excitations that can induce material modifications and phase transitions. Material properties can potentially be stabilized by rapid quenching. Pulsed ion beams with pulse lengths of order ns have recently become available for materials processing. Here, we optimize mask geometries for local modification of materials by intense ion pulses. The goal is to rapidly excite targets volumetrically to the point where a phase transition or local lattice reconstruction is induced followed by rapid cooling that stabilizes desired material's properties fast enough before the target is altered or damaged by, e.g., hydrodynamic expansion. By using a mask, the longitudinal dimension can be large compared to the transverse dimension, allowing the possibility of rapid transverse cooling. We performed HYDRA simulations that calculate peak temperatures for a series of excitation conditions and cooling rates of silicon targets with micro-structured masks and compare these to a simple analytical model. The model gives scaling laws that can guide the design of targets over a wide range of pulsed ion beam parameters.

Intense, pulsed, ion-diode sources and their application to mirror machines

International Nuclear Information System (INIS)

Prono, D.S.; Shearer, J.W.; Briggs, R.J.

1975-01-01

Startup conditions for future mirror fusion experiments require a rapidly formed target plasma of approximately 0.5 coulomb of ions with energy of 50 to 100 keV. Theory suggests that very intense ion-flux emission satisfying these requirements can be extracted from a pulsed ion diode. Developing such sources would be an ideal CTR application of the high-power, single-shot capability of pulsed power technology. Recent experimental results are reviewed in which approximately 2 kA/cm 2 of D + at approximately 50 keV was extracted. In the experiment, an intense relativistic electron beam undergoes many transits through a solid but range-thin anode foil. With each transit the electrons lose energy, causing their trajectories to collapse toward the anode surface. In so doing, the increased space charge extracts an intense ion flux from the anode foil's plasma. Observations are reported on the importance of diode stability. The general agreement between theoretical scaling laws and experimental results are also presented

Penning plasma based simultaneous light emission source of visible and VUV lights

Energy Technology Data Exchange (ETDEWEB)

Vyas, G. L., E-mail: glvyas27@gmail.com [Manipal University Jaipur (India); Prakash, R.; Pal, U. N. [CSIR-Central Electronics and Engineering Research Institute, Microwave Tubes Division (India); Manchanda, R. [Institute for Plasma Research (India); Halder, N. [Manipal University Jaipur (India)

2016-06-15

In this paper, a laboratory-based penning plasma discharge source is reported which has been developed in two anode configurations and is able to produce visible and VUV lights simultaneously. The developed source has simultaneous diagnostics facility using Langmuir probe and optical emission spectroscopy. The two anode configurations, namely, double ring and rectangular configurations, have been studied and compared for optimum use of the geometry for efficient light emissions and recording. The plasma is produced using helium gas and admixture of three noble gases including helium, neon, and argon. The source is capable to produce eight spectral lines for pure helium in the VUV range from 20 to 60 nm and total 24 spectral lines covering the wavelength range 20–106 nm for the admixture of gases. The large range of VUV lines is generated from gaseous admixture rather from the sputtered materials. The recorded spectrum shows that the plasma light radiations in both visible and VUV range are larger in double ring configuration than that of the rectangular configurations at the same discharge operating conditions. To clearly understand the difference, the imaging of the discharge using ICCD camera and particle-in-cell simulation using VORPAL have also been carried out. The effect of ion diffusion, metastable collision with the anode wall and the nonlinear effects are correlated to explain the results.

Effect of radiation damping on the interaction of ultra-intense laser pulses with an overdense plasma

International Nuclear Information System (INIS)

Zhidkov, Alexei; Koga, James; Sasaki, Akira; Ueshima, Yutaka

2001-01-01

The effect of radiation damping on the interaction of an ultra-intense laser pulse with an overdense plasma is studied via relativistic particle-in-cell simulation. The calculation is performed for a Cu solid slab including ionization. We find a strong effect from radiation damping on the electron energy cut-off at about 150 MeV and on the absorption of a laser pulse with an intensity I=5x10 22 W/cm 2 and duration of 20 fs. Hot electrons reradiate more then 10% of the laser energy during the laser pulse. With the laser intensity, the energy loss due to the radiation damping increases as I 3 . In addition, we observe that the laser pulse may not propagate in the plasma even if ω pl 2 /ω 2 γ<1. The increase of skin depth with the laser intensity due to relativistic effects gives rise to the absorption efficiency. (author)

Enhancement of VUV emission from a coaxial xenon excimer ultraviolet lamp driven by distorted bipolar square voltages

Energy Technology Data Exchange (ETDEWEB)

Jou, S.Y.; Hung, C.T.; Chiu, Y.M.; Wu, J.S. [Department of Mechanical Engineering, National Chiao Tung University, Hsinchu (China); Wei, B.Y. [High-Efficiency Gas Discharge Lamps Group, Material and Chemical Research Laboratories, Hsinchu (China)

2011-12-15

Enhancement of vacuum UV emission (172 nm VUV) from a coaxial xenon excimer UV lamp (EUV) driven by distorted 50 kHz bipolar square voltages, as compared to that by sinusoidal voltages, is investigated numerically in this paper. A self-consistent radial one-dimensional fluid model, taking into consideration non-local electron energy balance, is employed to simulate the discharge physics and chemistry. The discharge is divided into two three-period portions; these include: the pre-discharge, the discharge (most intense at 172 nm VUV emission) and the post-discharge periods. The results show that the efficiency of VUV emission using the distorted bipolar square voltages is much greater than when using sinusoidal voltages; this is attributed to two major mechanisms. The first is the much larger rate of change of the voltage in bipolar square voltages, in which only the electrons can efficiently absorb the power in a very short period of time. Energetic electrons then generate a higher concentration of metastable (and also excited dimer) xenon that is distributed more uniformly across the gap, for a longer period of time during the discharge process. The second is the comparably smaller amount of ''wasted'' power deposition by Xe{sup +}{sub 2} in the post-discharge period, as driven by distorted bipolar square voltages, because of the nearly vanishing gap voltage caused by the shielding effect resulting from accumulated charges on both dielectric surfaces (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Chirp analysis of high-order harmonics from atoms driven by intense femtosecond laser pulses

International Nuclear Information System (INIS)

Kim, Hyung Taek; Kim, I Jong; Hong, Kyung-Han; Lee, Dong Gun; Kim, Jung-Hoon; Nam, Chang Hee

2004-01-01

The spectral structure of harmonics was experimentally controlled by changing the chirp of femtosecond laser pulses, and the dependence of harmonic chirp on atomic species was analysed using harmonics from neon and helium. Experimental results and theoretical analysis based on the Wigner distribution function showed that the spectral structure varied sensitively to laser chirp and the harmonic chirp was determined by the competition between dynamically induced negative chirp and self-phase modulation induced positive chirp. The generation of sharp and bright harmonics was achieved with appropriately chirped laser pulses under given experimental conditions, especially negatively chirped pulses in the case of laser intensity above the saturation intensity for optical-field ionization

Pondermotive absorption of a short intense laser pulse in a non-uniform plasma

Energy Technology Data Exchange (ETDEWEB)

Andreev, A A; Platonov, K Yu [Inst. for Laser Physics, SC ` Vavilov State Optical Inst.` 12, Birzhevaya line, St Petersburg (Russian Federation); Tanaka, K A

1998-03-01

An analytical description of the pondermotive absorption mechanism at a short high intense laser pulse interaction with a strong inhomogeneous plasma is presented. The optimal conditions for the maximum of resonance absorption of laser pulse interaction with non-uniform plasma at normal incidence are founded. (author)

Control of ion beam generation in intense short pulse laser target interaction

International Nuclear Information System (INIS)

Nagashima, T.; Izumiyama, T.; Barada, D.; Kawata, S.; Gu, Y.J.; Wang, W.M.; Ma, Y.Y.; Kong, Q.

2013-01-01

In intense laser plasma interaction, several issues still remain to be solved for future laser particle acceleration. In this paper we focus on a control of generation of high-energy ions. In this study, near-critical density plasmas are employed and are illuminated by high intensity short laser pulses; we have successfully generated high-energy ions, and also controlled ion energy and the ion energy spectrum by multiple-stages acceleration. We performed particle-in-cell simulations in this paper. The first near-critical plasma target is illuminated by a laser pulse, and the ions accelerated are transferred to the next target. The next identical target is also illuminated by another identical large pulse, and the ion beam introduced is further accelerated and controlled. In this study four stages are employed, and finally a few hundreds of MeV of protons are realized. A quasi-monoenergetic energy spectrum is also obtained. (author)

A HIGH REPETITION RATE VUV-SOFT X-RAY FEL CONCEPT

International Nuclear Information System (INIS)

Corlett, J.; Byrd, J.; Fawley, W.M.; Gullans, M.; Li, D.; Lidia, S.M.; Padmore, H.; Penn, G.; Pogorelov, I.; Qiang, J.; Robin, D.; Sannibale, F.; Staples, J.W.; Steier, C.; Venturini, M.; Virostek, S.; Wan, W.; Wells, R.; Wilcox, R.; Wurtele, J.; Zholents, A.

2007-01-01

We report on design studies for a seeded FEL light source that is responsive to the scientific needs of the future. The FEL process increases radiation flux by several orders of magnitude above existing incoherent sources, and offers the additional enhancements attainable by optical manipulations of the electron beam: control of the temporal duration and bandwidth of the coherent output, reduced gain length in the FEL, utilization of harmonics to attain shorter wavelengths, and precise synchronization of the x-ray pulse with seed laser systems. We describe an FEL facility concept based on a high repetition rate RF photocathode gun, that would allow simultaneous operation of multiple independent FEL's, each producing high average brightness, tunable over the VUV-soft x-ray range, and each with individual performance characteristics determined by the configuration of the FEL. SASE, enhanced-SASE (ESASE), seeded, harmonic generation, and other configurations making use of optical manipulations of the electron beam may be employed, providing a wide range of photon beam properties to meet varied user demands

Suppression of Repeat-Intensive False Targets Based on Temporal Pulse Diversity

Directory of Open Access Journals (Sweden)

Gang Lu

2013-01-01

Full Text Available This paper considers the problem of suppressing the repeat-intensive false targets produced by a deception electronic attack (EA system equipped with a Digital Radio Frequency Memory (DRFM device. Different from a conventional repeat jammer, this type of jamming intensively retransmits the intercepted signal stored in a DRFM to the victim radar in a very short time-delay interval relative to a radar pulse wide. A multipeak matched-filtering output is then produced other than the merely expected true target. An electronic protection (EP algorithm based on the space time block code (STBC is proposed to suppress the adverse effects of this jammer. By transmitting a pulse sequence generated from the STBC in succession and the following cancellation process applied upon the received signal, this algorithm performs successfully in a single antenna system provided that the target models are nonfluctuating or slow fluctuating and the pulse repetition frequency (PRF is comparatively high. The performance in white and correlated Gaussian disturbance is evaluated by means of Monte Carlo simulations.

Short intense ion pulses for materials and warm dense matter research

Energy Technology Data Exchange (ETDEWEB)

Seidl, Peter A., E-mail: PASeidl@lbl.gov [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Persaud, Arun; Waldron, William L. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Barnard, John J. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Davidson, Ronald C. [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Friedman, Alex [Lawrence Livermore National Laboratory, Livermore, CA (United States); Gilson, Erik P. [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Greenway, Wayne G. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Grote, David P. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Kaganovich, Igor D. [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Lidia, Steven M.; Stettler, Matthew; Takakuwa, Jeffrey H.; Schenkel, Thomas [Lawrence Berkeley National Laboratory, Berkeley, CA (United States)

2015-11-11

We have commenced experiments with intense short pulses of ion beams on the Neutralized Drift Compression Experiment-II at Lawrence Berkeley National Laboratory, by generating beam spots size with radius r<1 mm within 2 ns FWHM and approximately 10{sup 10} ions/pulse. To enable the short pulse durations and mm-scale focal spot radii, the 1.2 MeV Li{sup +} ion beam is neutralized in a 1.6-meter drift compression section located after the last accelerator magnet. An 8-Tesla short focal length solenoid compresses the beam in the presence of the large volume plasma near the end of this section before the target. The scientific topics to be explored are warm dense matter, the dynamics of radiation damage in materials, and intense beam and beam-plasma physics including selected topics of relevance to the development of heavy-ion drivers for inertial fusion energy. Here we describe the accelerator commissioning and time-resolved ionoluminescence measurements of yttrium aluminum perovskite using the fully integrated accelerator and neutralized drift compression components.

Short intense ion pulses for materials and warm dense matter research

International Nuclear Information System (INIS)

Seidl, Peter A.; Persaud, Arun; Waldron, William L.; Barnard, John J.; Davidson, Ronald C.; Friedman, Alex; Gilson, Erik P.; Greenway, Wayne G.; Grote, David P.; Kaganovich, Igor D.; Lidia, Steven M.; Stettler, Matthew; Takakuwa, Jeffrey H.; Schenkel, Thomas

2015-01-01

We have commenced experiments with intense short pulses of ion beams on the Neutralized Drift Compression Experiment-II at Lawrence Berkeley National Laboratory, by generating beam spots size with radius r<1 mm within 2 ns FWHM and approximately 10"1"0 ions/pulse. To enable the short pulse durations and mm-scale focal spot radii, the 1.2 MeV Li"+ ion beam is neutralized in a 1.6-meter drift compression section located after the last accelerator magnet. An 8-Tesla short focal length solenoid compresses the beam in the presence of the large volume plasma near the end of this section before the target. The scientific topics to be explored are warm dense matter, the dynamics of radiation damage in materials, and intense beam and beam-plasma physics including selected topics of relevance to the development of heavy-ion drivers for inertial fusion energy. Here we describe the accelerator commissioning and time-resolved ionoluminescence measurements of yttrium aluminum perovskite using the fully integrated accelerator and neutralized drift compression components.

Comparison of low-intensity pulsed ultrasound and pulsed electromagnetic field treatments on OPG and RANKL expression in human osteoblast-like cells

NARCIS (Netherlands)

Borsje, Manon A.; Ren, Yijin; de Haan-Visser, H. Willy; Kuijer, Roel

OBJECTIVE: To compare two clinically applied treatments to stimulate bone healing-low-intensity pulsed ultrasound (LIPUS) and pulsed electromagnetic field (PEMF)-for their effects on RANKL and OPG expression in osteoblast-like cells in vitro. MATERIALS AND METHODS: LIPUS or PEMF was applied to

Two electron response to an intense x-ray free electron laser pulse

International Nuclear Information System (INIS)

Moore, L R; Parker, J S; Meharg, K J; Armstrong, G S J; Taylor, K T

2009-01-01

New x-ray free electron lasers (FELs) promise an ultra-fast ultra-intense regime in which new physical phenomena, such as double core hole formation in at atom, should become directly observable. Ahead of x-ray FEL experiments, an initial key task is to theoretically explore such fundamental laser-atom interactions and processes. To study the response of a two-electron positive ion to an intense x-ray FEL pulse, our theoretical approach is a direct numerical integration, incorporating non-dipole Hamiltonian terms, of the full six-dimensional time-dependent Schroedinger equation. We present probabilities of double K-shell ionization in the two-electron positive ions Ne 8+ and Ar 16+ exposed to x-ray FEL pulses with frequencies in the range 50 au to 300 au and intensities in the range 10 17 to 10 22 W/cm 2 .

Study of ultra-high gradient wakefield excitation by intense ultrashort laser pulses in plasma

International Nuclear Information System (INIS)

Kotaki, Hideyuki

2002-12-01

We investigate a mechanism of nonlinear phenomena in laser-plasma interaction, a laser wakefield excited by intense laser pulses, and the possibility of generating an intense bright electron source by an intense laser pulse. We need to understand and further employ some of these phenomena for our purposes. We measure self-focusing, filamentation, and the anomalous blueshift of the laser pulse. The ionization of gas with the self-focusing causes a broad continuous spectrum with blueshift. The normal blueshift depends on the laser intensity and the plasma density. We, however, have found different phenomenon. The laser spectrum shifts to fixed wavelength independent of the laser power and gas pressure above some critical power. We call the phenomenon 'anomalous blueshift'. The results are explained by the formation of filaments. An intense laser pulse can excite a laser wakefield in plasma. The coherent wakefield excited by 2 TW, 50 fs laser pulses in a gas-jet plasma around 10 18 cm -3 is measured with a time-resolved frequency domain interferometer (FDI). The density distribution of the helium gas is measured with a time-resolved Mach-Zehnder interferometer to search for the optimum laser focus position and timing in the gas-jet. The results show an accelerating wakefield excitation of 20 GeV/m with good coherency, which is useful for ultrahigh gradient particle acceleration in a compact system. This is the first time-resolved measurement of laser wakefield excitation in a gas-jet plasma. The experimental results are compared with a Particle-in-Cell (PIC) simulation. The pump-probe interferometer system of FDI and the anomalous blueshift will be modified to the optical injection system as a relativistic electron beam injector. In 1D PIC simulation we obtain the results of high quality intense electron beam acceleration. These results illuminate the possibility of a high energy and a high quality electron beam acceleration. (author)

Simultaneous nitrate reduction and acetaminophen oxidation using the continuous-flow chemical-less VUV process as an integrated advanced oxidation and reduction process

Energy Technology Data Exchange (ETDEWEB)

Moussavi, Gholamreza, E-mail: moussavi@modares.ac.ir; Shekoohiyan, Sakine

2016-11-15

Highlights: • Simultaneous advanced oxidation and reduction processes were explored in VUV system. • Complete reduction of nitrate to N{sub 2} was achieved at the presence of acetaminophen. • Complete degradation of acetaminophen was achieved at the presence of nitrate. • Over 95% of acetaminophen was mineralized in the VUV photoreactor. • VUV is a chemical-less advanced process for treating water emerging contaminants. - Abstract: This work was aimed at investigating the performance of the continuous-flow VUV photoreactor as a novel chemical-less advanced process for simultaneously oxidizing acetaminophen (ACT) as a model of pharmaceuticals and reducing nitrate in a single reactor. Solution pH was an important parameter affecting the performance of VUV; the highest ACT oxidation and nitrate reduction attained at solution pH between 6 and 8. The ACT was oxidized mainly by HO· while the aqueous electrons were the main working agents in the reduction of nitrate. The performance of VUV photoreactor improved with the increase of hydraulic retention time (HRT); the complete degradation of ACT and ∼99% reduction of nitrate with 100% N{sub 2} selectivity achieved at HRT of 80 min. The VUV effluent concentrations of nitrite and ammonium at HRT of 80 min were below the drinking water standards. The real water sample contaminated with the ACT and nitrate was efficiently treated in the VUV photoreactor. Therefore, the VUV photoreactor is a chemical-less advanced process in which both advanced oxidation and advanced reduction reactions are accomplished. This unique feature possesses VUV photoreactor as a promising method of treating water contaminated with both pharmaceutical and nitrate.

Simultaneous nitrate reduction and acetaminophen oxidation using the continuous-flow chemical-less VUV process as an integrated advanced oxidation and reduction process

International Nuclear Information System (INIS)

Moussavi, Gholamreza; Shekoohiyan, Sakine

2016-01-01

Highlights: • Simultaneous advanced oxidation and reduction processes were explored in VUV system. • Complete reduction of nitrate to N_2 was achieved at the presence of acetaminophen. • Complete degradation of acetaminophen was achieved at the presence of nitrate. • Over 95% of acetaminophen was mineralized in the VUV photoreactor. • VUV is a chemical-less advanced process for treating water emerging contaminants. - Abstract: This work was aimed at investigating the performance of the continuous-flow VUV photoreactor as a novel chemical-less advanced process for simultaneously oxidizing acetaminophen (ACT) as a model of pharmaceuticals and reducing nitrate in a single reactor. Solution pH was an important parameter affecting the performance of VUV; the highest ACT oxidation and nitrate reduction attained at solution pH between 6 and 8. The ACT was oxidized mainly by HO· while the aqueous electrons were the main working agents in the reduction of nitrate. The performance of VUV photoreactor improved with the increase of hydraulic retention time (HRT); the complete degradation of ACT and ∼99% reduction of nitrate with 100% N_2 selectivity achieved at HRT of 80 min. The VUV effluent concentrations of nitrite and ammonium at HRT of 80 min were below the drinking water standards. The real water sample contaminated with the ACT and nitrate was efficiently treated in the VUV photoreactor. Therefore, the VUV photoreactor is a chemical-less advanced process in which both advanced oxidation and advanced reduction reactions are accomplished. This unique feature possesses VUV photoreactor as a promising method of treating water contaminated with both pharmaceutical and nitrate.

Atmospheric pressure photoionization using tunable VUV synchrotron radiation

International Nuclear Information System (INIS)

Giuliani, A.; Giorgetta, J.-L.; Ricaud, J.-P.; Jamme, F.; Rouam, V.; Wien, F.; Laprévote, O.; Réfrégiers, M.

2012-01-01

Highlights: ► Coupling of an atmospheric pressure photoionization source with a vacuum ultra-violet (VUV) beamline. ► The set up allows photoionization up to 20 eV. ► Compared to classical atmospheric pressure photoionization (APPI), our set up offers spectral purity and tunability. ► Allows photoionization mass spectrometry on fragile and hard to vaporize molecules. - Abstract: We report here the first coupling of an atmospheric pressure photoionization (APPI) source with a synchrotron radiation beamline in the vacuum ultra-violet (VUV). A commercial APPI source of a QStar Pulsar i from AB Sciex was modified to receive photons from the DISCO beamline at the SOLEIL synchrotron radiation facility. Photons are delivered at atmospheric pressure in the 4–20 eV range. The advantages of this new set up, termed SR-APPI, over classical APPI are spectral purity and continuous tunability. The technique may also be used to perform tunable photoionization mass spectrometry on fragile compounds difficult to vaporize by classical methods.

Two electron response to an intense x-ray free electron laser pulse

Energy Technology Data Exchange (ETDEWEB)

Moore, L R; Parker, J S; Meharg, K J; Armstrong, G S J; Taylor, K T, E-mail: l.moore@qub.ac.u [DAMTP, David Bates Building, Queen' s University Belfast, Belfast, BT7 1NN (United Kingdom)

2009-11-01

New x-ray free electron lasers (FELs) promise an ultra-fast ultra-intense regime in which new physical phenomena, such as double core hole formation in at atom, should become directly observable. Ahead of x-ray FEL experiments, an initial key task is to theoretically explore such fundamental laser-atom interactions and processes. To study the response of a two-electron positive ion to an intense x-ray FEL pulse, our theoretical approach is a direct numerical integration, incorporating non-dipole Hamiltonian terms, of the full six-dimensional time-dependent Schroedinger equation. We present probabilities of double K-shell ionization in the two-electron positive ions Ne{sup 8+} and Ar{sup 16+} exposed to x-ray FEL pulses with frequencies in the range 50 au to 300 au and intensities in the range 10{sup 17} to 10{sup 22} W/cm{sup 2}.

International Conference on the Interaction of atoms, molecules and plasmas with intense ultrashort laser pulses. Book of abstracts

International Nuclear Information System (INIS)

2006-01-01

International Conference on the Interaction of atoms, molecules and plasmas with intense ultrashort laser pulses was held in Hungary in 2006. This conference which joined the ULTRA COST activity ('Laser-matter interactions with ultra-short pulses, high-frequency pulses and ultra-intense pulses. From attophysics to petawatt physics') and the XTRA ('Ultrashort XUV Pulses for Time-Resolved and Non-Linear Applications') Marie-Curie Research Training Network, intends to offer a possibility to the members of both of these activities to exchange ideas on recent theoretical and experimental results on the interaction of ultrashort laser pulses with matter giving a broad view from theoretical models to practical and technical applications. Ultrashort laser pulses reaching extra high intensities open new windows to obtain information about molecular and atomic processes. These pulses are even able to penetrate into atomic scalelengths not only by generating particles of ultrahigh energy but also inside the spatial and temporal atomic scalelengths. New regimes of laser-matter interaction were opened in the last decade with an increasing number of laboratories and researchers in these fields. (S.I.)

Photocurrent and photovoltage induced in a 2DEG under intense, pulsed THz radiation

International Nuclear Information System (INIS)

Lewis, R.A.; Xu, W.; Pellemans, H.P.M.; Langerak, C.J.G.M.

1999-01-01

Full text: Intense THz radiation emitted by FELIX (Free Electron Laser for Infrared eXperiments) induces both photovoltage and photocurrent signals in a high-mobility (μ = 2 x 10 6 cm 2 /V s), low-density (n e = 2 x 10 11 cm -2 ) GaAs/AlGaAs-based 2DEG. Within the ∼5 μs FELIX macropulse, there is a rapid response in the longitudinal voltage of a Hall-bar sample, reproducible between pulses. A large response continues well after the pulse; this long-time-scale behaviour varies between pulses if the current exceeds a critical value (which decreases with radiation intensity and magnetic field). Within the macropulse, the photovoltage varies with magnetic field, saturating at low field (<100 mT). The photocurrent shows a rapid, non-resonant response, evident at integral filling factors in both longitudinal and transverse data, and a slower, cyclotron resonant response, peaking at ∼390 μs after the FELIX pulse. No anisotropy in the resistivity under polarised radiation was found

Status of the intense pulsed neutron source

International Nuclear Information System (INIS)

Carpenter, J.M.; Brown, B.S.; Kustom, R.L.; Lander, G.H.; Potts, C.W.; Schulke, A.W.; Wuestefeld, G.

1985-01-01

Fortunately in spite of some premature reports of its impending demise, IPNS has passed the fourth anniversary of the first delivery of protons to the targets (May 5, 1981) and is approaching the fourth anniversary of its operation as a scattering facility (August 4, 1981). On June 10, 1984, the RCS delivered its one billionth pulse to the IPNS target - the total number of protons delivered to the targets amounted then to 75 stp cm 3 of H 2 gas. Since startup IPNS has improved steadily in terms of the performance of the Rapid Cycling Synchrotron, the source and its moderators and the scattering instruments, and a substantial and productive user program has evolved. This report summarizes the current status of the Intense Pulsed Neutron Source at Argonne National Laboratory. We include reference to recent accelerator operating experience, neutron facility operating experience, improvements to these systems, design work on the ASPUN high-current facility, booster target design, the new solid methane moderator, characterization of the room temperature moderators, and provide some examples of recent results from several of the spectrometers

VUV/UV light inducing accelerated phenol degradation with a low electric input.

Science.gov (United States)

Li, Mengkai; Wen, Dong; Qiang, Zhimin; Kiwi, John

2017-01-23

This study presents the first evidence for the accelerated degradation of phenol by Fenton's reagent in a mini-fluidic VUV/UV photoreaction system (MVPS). A low-pressure mercury lamp used in the MVPS led to a complete degradation of phenol within 4-6 min. The HO˙ and HO 2 ˙ originating from both Fenton's reagent and VUV photolysis of water were identified with suitable radical scavengers. The effects of initial concentrations of phenol, H 2 O 2 and Fe 3+ as well as solution pH on phenol degradation kinetics were examined. Increasing the initial phenol concentration slowed down the phenol degradation, whereas increasing the initial H 2 O 2 or Fe 3+ concentration accelerated the phenol degradation. The optimal solution pH was 3.7. At both 254 and 185 nm, increasing phenol concentration enhanced its absorption for the incident photons. The reaction mechanism for the degradation of phenol was suggested consistent with the results obtained. This study indicates that the VUV/UV photo-Fenton process has potential applications in the treatment of industrial wastewater containing phenol and related aromatic pollutants.

The extreme condition analyzing for NEMPI shielding of electronic system in high-intensity pulsed radiation diagnosing

International Nuclear Information System (INIS)

Cheng Xiaolei; Liu Fang; Ouyang Xiaoping

2012-01-01

The difficulty for estimating the NEMPI (electromagnetic pulsed interference caused by the nuclear reaction) on the electronic system in high-intensity pulsed radiation diagnosing is analyzed in this article. To solve the difficulty, a method called 'Extreme Condition Analyzing' is presented for estimating the NEMPI conservatively and reliably. Through an extreme condition hypothesizing which could be described as 'Entire Coupling of Electric Field Energy', the E max (maximum electric field intensity which could be endured by the electronic system in the high-intensity pulsed radiation) could be figured out without any other information of the EMP caused by the nuclear reaction. Then a feasibility inspection is introduced, to confirm that the EMPI shielding request according to E max is not too extreme to be achieved. (authors)

Self-guiding of high-intensity laser pulses for laser wake field acceleration

International Nuclear Information System (INIS)

Umstader, D.; Liu, X.

1992-01-01

A means of self-guiding an ultrashort and high-intensity laser pulse is demonstrated both experimentally and numerically. Its relevance to the laser wake field accelerator concept is discussed. Self-focusing and multiple foci formation are observed when a high peak power (P>100 GW), 1 μm, subpicosecond laser is focused onto various gases (air or hydrogen). It appears to result from the combined effects of self-focusing by the gas, and de-focusing both by diffraction and the plasma formed in the central high-intensity region. Quasi-stationary computer simulations show the same multiple foci behavior as the experiments. The results suggest much larger nonlinear electronic susceptibilities of a gas near or undergoing ionization in the high field of the laser pulse. Although self-guiding of a laser beam by this mechanism appears to significantly extend its high-intensity focal region, small-scale self-focusing due to beam non-uniformity is currently a limitation

Intra-pulse transition between ion acceleration mechanisms in intense laser-foil interactions

Energy Technology Data Exchange (ETDEWEB)

Padda, H.; King, M.; Gray, R. J.; Powell, H. W.; Gonzalez-Izquierdo, B.; Wilson, R.; Dance, R. J.; MacLellan, D. A.; Butler, N. M. H.; Capdessus, R.; McKenna, P., E-mail: paul.mckenna@strath.ac.uk [SUPA Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Stockhausen, L. C. [Centro de Laseres Pulsados (CLPU), Parque Cientifico, Calle del Adaja s/n. 37185 Villamayor, Salamanca (Spain); Carroll, D. C. [Central Laser Facility, STFC Rutherford Appleton Laboratory, Oxfordshire OX11 0QX (United Kingdom); Yuan, X. H. [Key Laboratory for Laser Plasmas (Ministry of Education) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center of IFSA (CICIFSA), Shanghai Jiao Tong University, Shanghai 200240 (China); Borghesi, M. [Centre for Plasma Physics, Queens University Belfast, Belfast BT7 1NN (United Kingdom); Neely, D. [SUPA Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Central Laser Facility, STFC Rutherford Appleton Laboratory, Oxfordshire OX11 0QX (United Kingdom)

2016-06-15

Multiple ion acceleration mechanisms can occur when an ultrathin foil is irradiated with an intense laser pulse, with the dominant mechanism changing over the course of the interaction. Measurement of the spatial-intensity distribution of the beam of energetic protons is used to investigate the transition from radiation pressure acceleration to transparency-driven processes. It is shown numerically that radiation pressure drives an increased expansion of the target ions within the spatial extent of the laser focal spot, which induces a radial deflection of relatively low energy sheath-accelerated protons to form an annular distribution. Through variation of the target foil thickness, the opening angle of the ring is shown to be correlated to the point in time transparency occurs during the interaction and is maximized when it occurs at the peak of the laser intensity profile. Corresponding experimental measurements of the ring size variation with target thickness exhibit the same trends and provide insight into the intra-pulse laser-plasma evolution.

Efficient coupling of high intensity short laser pulses into snow clusters

Science.gov (United States)

Palchan, T.; Pecker, S.; Henis, Z.; Eisenmann, S.; Zigler, A.

2007-01-01

Measurements of energy absorption of high intensity laser pulses in snow clusters are reported. Targets consisting of sapphire coated with snow nanoparticles were found to absorb more than 95% of the incident light compared to 50% absorption in flat sapphire targets.

Photochemical decomposition of perfluorooctanoic acid in aqueous periodate with VUV and UV light irradiation

International Nuclear Information System (INIS)

Cao, M.H.; Wang, B.B.; Yu, H.S.; Wang, L.L.; Yuan, S.H.; Chen, J.

2010-01-01

The photochemical decomposition of perfluorooctanoic acid (PFOA) in aqueous periodate (IO 4 - ) was investigated under two types of low-pressure mercury lamps: one emits at 254 nm light (UV light) and the other emits both 254 nm and 185 nm light (VUV light). PFOA decomposed efficiently under VUV light irradiation while it decomposed poorly under UV light irradiation. The addition of IO 4 - significantly increased the rate of decomposition and defluorination of PFOA irradiated with UV light whereas it decreased both processes under VUV irradiation. Reactive radical (IO 3 ·) generated by photolysis of IO 4 - initiated the oxidation of PFOA in UV process. Aquated electrons (e aq - ), generated from water homolysis, scavenged IO 4 - resulting in decrease of reactive radical species production and PFOA decomposition. The shorter-chain perfluorocarboxylic acids (PFCAs) formed in a stepwise manner from long-chain PFCAs.

Generation of mega-electron-volt electron beams by an ultrafast intense laser pulse

International Nuclear Information System (INIS)

Wang Xiaofang; Saleh, Ned; Krishnan, Mohan; Wang Haiwen; Backus, Sterling; Murnane, Margaret; Kapteyn, Henry; Umstadter, Donald; Wang Quandong; Shen Baifei

2003-01-01

Mega-electron-volt (MeV) electron emission from the interaction of an ultrafast (τ∼29 fs), intense (>10 18 W/cm 2 ) laser pulse with underdense plasmas has been studied. A beam of MeV electrons with a divergence angle as small as 1 deg. is observed in the forward direction, which is correlated with relativistic filamentation of the laser pulse in plasmas. A novel net-energy-gain mechanism is proposed for electron acceleration resulting from the relativistic filamentation and beam breakup. These results suggest an approach for generating a beam of femtosecond, MeV electrons at a kilohertz repetition rate with a compact ultrafast intense laser system

Growth and apoptosis of HeLa cells induced by intense picosecond pulsed electric field

Directory of Open Access Journals (Sweden)

Yuan-yuan HUA

2011-07-01

Full Text Available Objective To investigate the growth and apoptosis of HeLa cells induced by intense picosecond pulsed electric field(PEF in vitro.Methods HeLa cells cultured in vitro were divided into experimental group and control group(with or without intense picosecond PEF.With constant pulse width,frequency and voltage,the cells in experimental group were divided into 6 sub-groups according to the number of pulse(100,200,500,1000,1500,2000,the growth inhibition of HeLa cells by PEF and the dose-effect relationship were analyzed by MTT.Caspase 3 protein activity was detected in the cells in 500,1000 and 2000 sub-groups.Mitochondrial transmembrane potential was detected by rhodamine 123 staining with the cells in 2000 sub-groups.Results MTT assay demonstrated that intense picosecond PEF significantly inhibited the proliferation of HeLa cells in dose-dependent manner.The survival rates of cells declined along with the increase in pulse number,and were 96.23%±0.76%,94.11%±2.42%,90.31%±1.77%,64.59%±1.59%,32.95%±0.73%,23.85%±2.38% and 100%,respectively,in 100,200,500,1000,1500,2000 sub-groups and control group(P < 0.01.The Caspase 3 protein activity was significantly enhanced by intense picosecond PEF,and the absorbancy indexes(A were 0.174±0.012,0.232±0.017,0.365±0.016 and 0.122±0.011,respectively,in 500,1000,2000 sub-groups and control group(P < 0.05.The mitochondrial transmembrane potential of HeLa cells was significantly inhibited by intense picosecond PEF,and the fluorescence intensity in 2000 sub-group(76.66±13.38 was much lower than that in control group(155.81±2.33,P < 0.05.Conclusion Intense picosecond PEF may significantly inhibit the growth of HeLa cells,and induce cell apoptosis via mitochondrial pathway.

Rydberg states of chloroform studied by VUV photoabsorption spectroscopy

International Nuclear Information System (INIS)

Singh, Param Jeet; Shastri, Aparna; D’Souza, R.; Jagatap, B.N.

2013-01-01

The VUV photoabsorption spectra of CHCl 3 and CDCl 3 in the energy region 6.2–11.8 eV (50,000–95,000 cm −1 ) have been investigated using synchrotron radiation from the Indus-1 source. Rydberg series converging to the first four ionization limits at 11.48, 11.91, 12.01 and 12.85 eV corresponding to excitation from the 1a 2 , 4a 1 , 4e, 3e, orbitals of CHCl 3 respectively are identified and analyzed. Quantum defect values are observed to be consistent with excitation from the chlorine lone pair orbitals. Vibrational progressions observed in the region of 72,500–76,500 cm −1 have been reassigned to ν 3 and combination modes of ν 3 +ν 6 belonging to the 1a 2 →4p transition in contrast to earlier studies where they were assigned to a ν 3 progression superimposed on the 3e→4p Rydberg transition. The assignments are further confirmed based on isotopic substitution studies on CDCl 3 whose VUV photoabsorption spectrum is reported here for the first time. The frequencies of the ν 3 and ν 6 modes in the 4p Rydberg state of CHCl 3 (CDCl 3 ) are proposed to be ∼454 (409) cm −1 and∼130 (129) cm −1 respectively based on the vibronic analysis. DFT calculations of neutral and ionic ground state vibrational frequencies support the vibronic analysis. Experimental spectrum is found to be in good agreement with that predicted by TDDFT calculations. This work presents a consolidated analysis of the VUV photoabsorption spectrum of chloroform. -- Highlights: •VUV photoabsorption spectra of CHCl 3 and CDCl 3 studied using synchrotron radiation. •Quantum defect analysis of Rydberg series converging to first four ionization limits. •Vibronic bands in 72,500–76,500 cm −1 region assigned to 1a 2 →4p Rydberg transition. •Vibrational progressions assigned to ν 3 and ν 3 +ν 6 using ab initio calculations. •Excellent agreement of TDDFT vertical excited energies with experimental spectrum

Primary power supply of repetitive pulsed intense current accelerator charged by capacitance of energy store

International Nuclear Information System (INIS)

Chen Jun; Yang Jianhua; Shu Ting; Zhang Jiande; Zhou Xiang; Wen Jianchun

2008-01-01

The primary power supply of repetitive pulsed intense current accelerator charged by capacitance of energy store is studied. The principle of primary power supply circuit and its time diagram of switches are presented. The circuit is analyzed and some expressions are got, especially, the usable voltage scope of capacitance of energy store, and the correlation between the parameters of circuit and time delay, which is between the turn-on of the charging circuit of capacitance of energy store and the circuit of recuperation. The time delay of 256 x 256 lookup table is made with the instruction of theory and the simulation of the actual parameters of circuits. The table is used by the control program to control the repetitive operating of the actual pulsed intense current accelerator. Finally, some conclusions of the primary power supply of repetitive pulsed intense current accelerator charged by capacitance of energy store are got. (authors)

Monitoring of transient cavitation induced by ultrasound and intense pulsed light in presence of gold nanoparticles.

Science.gov (United States)

Sazgarnia, Ameneh; Shanei, Ahmad; Shanei, Mohammad Mahdi

2014-01-01

One of the most important challenges in medical treatment is invention of a minimally invasive approach in order to induce lethal damages to cancer cells. Application of high intensity focused ultrasound can be beneficial to achieve this goal via the cavitation process. Existence of the particles and vapor in a liquid decreases the ultrasonic intensity threshold required for cavitation onset. In this study, synergism of intense pulsed light (IPL) and gold nanoparticles (GNPs) has been investigated as a means of providing nucleation sites for acoustic cavitation. Several approaches have been reported with the aim of cavitation monitoring. We conducted the experiments on the basis of sonochemiluminescence (SCL) and chemical dosimetric methods. The acoustic cavitation activity was investigated by determining the integrated SCL signal acquired over polyacrylamide gel phantoms containing luminol in the presence and absence of GNPs in the wavelength range of 400-500 nm using a spectrometer equipped with cooled charged coupled devices (CCD) during irradiation by different intensities of 1 MHz ultrasound and IPL pulses. In order to confirm these results, the terephthalic acid chemical dosimeter was utilized as well. The SCL signal recorded in the gel phantoms containing GNPs at different intensities of ultrasound in the presence of intense pulsed light was higher than the gel phantoms without GNPs. These results have been confirmed by the obtained data from the chemical dosimetry method. Acoustic cavitation in the presence of GNPs and intense pulsed light has been suggested as a new approach designed for decreasing threshold intensity of acoustic cavitation and improving targeted therapeutic effects. Copyright © 2013 Elsevier B.V. All rights reserved.

Interrogation of orbital structure by elliptically polarized intense femtosecond laser pulses

DEFF Research Database (Denmark)

Abu-Samha, Mahmoud; Madsen, Lars Bojer

2011-01-01

We solve the three-dimensional time-dependent Schrödinger equation and present investigations of the imprint of the orbital angular node in photoelectron momentum distributions of an aligned atomic p-type orbital following ionization by an intense elliptically polarized laser pulse of femtosecond...

National Synchrotron Light Source user's manual: Guide to the VUV and x-ray beamlines

International Nuclear Information System (INIS)

Gmuer, N.F.

1993-04-01

The success of the National Synchrotron Light Source is based, in large part, on the size of the user community and the diversity of the scientific and technical disciplines represented by these users. As evidence of this success, the VUV Ring has just celebrated its 10th anniversary and the X-ray Ring will do the same in 1995. In order to enhance this success, the NSLS User's Manual: Guide to the VUV and X-Ray Beamlines - Fifth Edition, is being published. This Manual presents to the scientific community-at-large the current and projected architecture, capabilities and research programs of the various VUV and X-ray beamlines. Also detailed is the research and computer equipment a General User can expect to find and use at each beamline when working at the NSLS. The Manual is updated periodically in order to keep pace with the constant changes on these beamlines

Long-distance propagation of intense short laser pulse in air

International Nuclear Information System (INIS)

Yu Wei; Yu, M.Y.; Zhang, J.; Qian, L.J.; Yuan, X.; Lu, P.X.; Li, R.X.; Sheng, Z.M.; Liu, J.R.; Xu, Z.Z.

2004-01-01

Long-distance propagation of intense laser pulse in air is reconsidered analytically by generalizing the analogy between the laser spotsize and the orbit of a classical particle. It is shown that multiphoton ionization introduces unique features to the laser-air interaction, thereby enabling the long-distance behavior. Several interesting characteristics of the latter are pointed out

Simultaneous nitrate reduction and acetaminophen oxidation using the continuous-flow chemical-less VUV process as an integrated advanced oxidation and reduction process.

Science.gov (United States)

Moussavi, Gholamreza; Shekoohiyan, Sakine

2016-11-15

This work was aimed at investigating the performance of the continuous-flow VUV photoreactor as a novel chemical-less advanced process for simultaneously oxidizing acetaminophen (ACT) as a model of pharmaceuticals and reducing nitrate in a single reactor. Solution pH was an important parameter affecting the performance of VUV; the highest ACT oxidation and nitrate reduction attained at solution pH between 6 and 8. The ACT was oxidized mainly by HO while the aqueous electrons were the main working agents in the reduction of nitrate. The performance of VUV photoreactor improved with the increase of hydraulic retention time (HRT); the complete degradation of ACT and ∼99% reduction of nitrate with 100% N2 selectivity achieved at HRT of 80min. The VUV effluent concentrations of nitrite and ammonium at HRT of 80min were below the drinking water standards. The real water sample contaminated with the ACT and nitrate was efficiently treated in the VUV photoreactor. Therefore, the VUV photoreactor is a chemical-less advanced process in which both advanced oxidation and advanced reduction reactions are accomplished. This unique feature possesses VUV photoreactor as a promising method of treating water contaminated with both pharmaceutical and nitrate. Copyright © 2016 Elsevier B.V. All rights reserved.

Physics of neutralization of intense high-energy ion beam pulses by electrons

International Nuclear Information System (INIS)

Kaganovich, I. D.; Davidson, R. C.; Dorf, M. A.; Startsev, E. A.; Sefkow, A. B.; Lee, E. P.; Friedman, A.

2010-01-01

Neutralization and focusing of intense charged particle beam pulses by electrons form the basis for a wide range of applications to high energy accelerators and colliders, heavy ion fusion, and astrophysics. For example, for ballistic propagation of intense ion beam pulses, background plasma can be used to effectively neutralize the beam charge and current, so that the self-electric and self-magnetic fields do not affect the ballistic propagation of the beam. From the practical perspective of designing advanced plasma sources for beam neutralization, a robust theory should be able to predict the self-electric and self-magnetic fields during beam propagation through the background plasma. The major scaling relations for the self-electric and self-magnetic fields of intense ion charge bunches propagating through background plasma have been determined taking into account the effects of transients during beam entry into the plasma, the excitation of collective plasma waves, the effects of gas ionization, finite electron temperature, and applied solenoidal and dipole magnetic fields. Accounting for plasma production by gas ionization yields a larger self-magnetic field of the ion beam compared to the case without ionization, and a wake of current density and self-magnetic field perturbations is generated behind the beam pulse. A solenoidal magnetic field can be applied for controlling the beam propagation. Making use of theoretical models and advanced numerical simulations, it is shown that even a small applied magnetic field of about 100 G can strongly affect the beam neutralization. It has also been demonstrated that in the presence of an applied magnetic field the ion beam pulse can excite large-amplitude whistler waves, thereby producing a complex structure of self-electric and self-magnetic fields. The presence of an applied solenoidal magnetic field may also cause a strong enhancement of the radial self-electric field of the beam pulse propagating through the

Physics of Neutralization of Intense High-Energy Ion Beam Pulses by Electrons

International Nuclear Information System (INIS)

Kaganovich, I.D.; Davidson, R.C.; Dorf, M.A.; Startsev, E.A.; Sefkow, A.B.; Lee, E.P.; Friedman, A.

2010-01-01

Neutralization and focusing of intense charged particle beam pulses by electrons forms the basis for a wide range of applications to high energy accelerators and colliders, heavy ion fusion, and astrophysics. For example, for ballistic propagation of intense ion beam pulses, background plasma can be used to effectively neutralize the beam charge and current, so that the self-electric and self- magnetic fields do not affect the ballistic propagation of the beam. From the practical perspective of designing advanced plasma sources for beam neutralization, a robust theory should be able to predict the self-electric and self-magnetic fields during beam propagation through the background plasma. The major scaling relations for the self-electric and self-magnetic fields of intense ion charge bunches propagating through background plasma have been determined taking into account the effects of transients during beam entry into the plasma, the excitation of collective plasma waves, the effects of gas ionization, finite electron temperature, and applied solenoidal and dipole magnetic fields. Accounting for plasma production by gas ionization yields a larger self-magnetic field of the ion beam compared to the case without ionization, and a wake of current density and self-magnetic field perturbations is generated behind the beam pulse. A solenoidal magnetic field can be applied for controlling the beam propagation. Making use of theoretical models and advanced numerical simulations, it is shown that even a small applied magnetic field of about 100G can strongly affect the beam neutralization. It has also been demonstrated that in the presence of an applied magnetic field the ion beam pulse can excite large-amplitude whistler waves, thereby producing a complex structure of self-electric and self-magnetic fields. The presence of an applied solenoidal magnetic field may also cause a strong enhancement of the radial self-electric field of the beam pulse propagating through the

Ultra-intense, short pulse laser-plasma interactions with applications to the fast ignitor

International Nuclear Information System (INIS)

Wilks, S.C.; Kruer, W.L.; Young, P.E.; Hammer, J.; Tabak, M.

1995-04-01

Due to the advent of chirped pulse amplification (CPA) as an efficient means of creating ultra-high intensity laser light (I > 5x10 17 W/cm 2 ) in pulses less than a few picoseconds, new ideas for achieving ignition and gain in DT targets with less than 1 megajoule of input energy are currently being pursued. Two types of powerful lasers are employed in this scheme: (1) channeling beams and (2) ignition beams. The current state of laser-plasma interactions relating to this fusion scheme will be discussed. In particular, plasma physics issues in the ultra-intense regime are crucial to the success of this scheme. We compare simulation and experimental results in this highly nonlinear regime

Temperature-dependent absorption cross-section measurements of 1-butene (1-C4H8) in VUV and IR

KAUST Repository

Es-sebbar, Et-touhami; Bé nilan, Yves; Farooq, Aamir

2013-01-01

synchrotron radiation as a tunable VUV light source. Fourier Transform Infrared (FTIR) spectroscopy is employed to measure absorption cross-section and band strengths in the IR region between 1.54 and 25μm (~6500-400cm-1). The measured room-temperature VUV

The interaction of intense subpicosecond laser pulses with underdense plasmas

Energy Technology Data Exchange (ETDEWEB)

Coverdale, Christine Ann [Univ. of California, Davis, CA (United States)

1995-05-11

Laser-plasma interactions have been of interest for many years not only from a basic physics standpoint, but also for their relevance to numerous applications. Advances in laser technology in recent years have resulted in compact laser systems capable of generating (psec), 10¹⁶ W/cm² laser pulses. These lasers have provided a new regime in which to study laser-plasma interactions, a regime characterized by L_plasma ≥ 2L_Rayleigh > cτ. The goal of this dissertation is to experimentally characterize the interaction of a short pulse, high intensity laser with an underdense plasma (n_o ≤ 0.05n_cr). Specifically, the parametric instability known as stimulated Raman scatter (SRS) is investigated to determine its behavior when driven by a short, intense laser pulse. Both the forward Raman scatter instability and backscattered Raman instability are studied. The coupled partial differential equations which describe the growth of SRS are reviewed and solved for typical experimental laser and plasma parameters. This solution shows the growth of the waves (electron plasma and scattered light) generated via stimulated Raman scatter. The dispersion relation is also derived and solved for experimentally accessible parameters. The solution of the dispersion relation is used to predict where (in k-space) and at what frequency (in ω-space) the instability will grow. Both the nonrelativistic and relativistic regimes of the instability are considered.

Collisionless energy absorption in the short-pulse intense laser-cluster interaction

International Nuclear Information System (INIS)

Kundu, M.; Bauer, D.

2006-01-01

In a previous paper [Phys. Rev. Lett. 96, 123401 (2006)] we have shown by means of three-dimensional particle-in-cell simulations and a simple rigid-sphere model that nonlinear resonance absorption is the dominant collisionless absorption mechanism in the intense, short-pulse laser cluster interaction. In this paper we present a more detailed account of the matter. In particular we show that the absorption efficiency is almost independent of the laser polarization. In the rigid-sphere model, the absorbed energy increases by many orders of magnitude at a certain threshold laser intensity. The particle-in-cell results display maximum fractional absorption around the same intensity. We calculate the threshold intensity and show that it is underestimated by the common overbarrier ionization estimate

A search for the sulphur hexafluoride cation with intense, few cycle laser pulses

Energy Technology Data Exchange (ETDEWEB)

Dota, Krithika; Mathur, Deepak, E-mail: atmol1@tifr.res.in [Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400 005 (India); Centre for Atomic and Molecular Physics, Manipal University, Manipal 576 104 (India); Dharmadhikari, Aditya K. [Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400 005 (India); Dharmadhikari, Jayashree A. [Centre for Atomic and Molecular Physics, Manipal University, Manipal 576 104 (India); Patra, Kaustuv; Tiwari, Ashwani K. [Indian Institute of Science Education and Research - Kolkata, Mohanpur 741 252 (India)

2013-11-21

It is well established that upon ionization of sulphur hexafluoride, the SF{sub 6}{sup +} ion is never observed in mass spectra. Recent work with ultrashort intense laser pulses has offered indications that when strong optical field are used, the resulting “bond hardening” can induce changes in the potential energy surfaces of molecular cations such that molecular ions that are normally unstable may, indeed, become metastable enough to enable their detection by mass spectrometry. Do intense, ultrashort laser pulses permit formation of SF{sub 6}{sup +}? We have utilized intense pulses of 5 fs, 11 fs, and 22 fs to explore this possibility. Our results are negative: no evidence is discovered for SF{sub 6}{sup +}. However, multiply charged sulphur and fluorine ions from highly charged SF{sub 6}{sup q+} ions are observed that enable us to resolve the controversy regarding the kinetic energy release accompanying formation of F{sup +} fragment ions. Quantum chemical computations of field-distorted potential energy curves of SF{sub 6} and its molecular ion enable us to rationalize our non-observation of SF{sub 6}{sup +}. Our findings have implications for high harmonic generation from SF{sub 6} in the few-cycle regime.

Generation of ultra-intense and ultra-short laser pulses with high temporal contrast

International Nuclear Information System (INIS)

Julien, A.

2006-03-01

The topic of this thesis work concerns the design and the characterization of an efficient device devoted to the temporal contrast improvement for ultra-intense femtosecond laser pulses. The contrast is defined as the intensity ratio between the main femtosecond pulse and its nanosecond pedestal. This pedestal is the amplified spontaneous emission (ASE), inherent with laser amplification mechanism. The ASE background has dramatic effects for laser-matter interactions on a solid target. The presented work consists in the theoretical and experimental study of a temporal filter based on a third order nonlinear effect acting on the pulse polarization. We have studied several kinds of nonlinear filters. The selected device is based on the process of cross-polarized wave generation (XPW) in crystals with an anisotropic third-order nonlinear susceptibility. This nonlinear filter has been experimented on various femtosecond systems. It allows a contrast improvement of several orders of magnitude, as demonstrated by temporal profiles measurements on a large intensity dynamic. A device to improve the nonlinear process conversion efficiency, it means the filter transmission, has also been achieved. This method is based on constructive interferences between XPW signals generated in different crystals. This setup has made it possible to reach experimentally the maximum theoretical efficiency ( >20%) and in the same time ensures the system stability. At least, we have demonstrated that the filter preserves, or even improves, spectral and spatial qualities of the laser pulse. These results are thus particularly promising and allow contemplating the implementation of the filter in current femtosecond systems. (author)

Proposed second harmonic acceleration system for the intense pulsed neutron source rapid cycling synchrotron

International Nuclear Information System (INIS)

Norem, J.; Brandeberry, F.; Rauchas, A.

1983-01-01

The Rapid Cycling Synchrotron (RCS) of the Intense Pulsed Neutron Source (IPNS) operating at Argonne National Laboratory is presently producing intensities of 2 to 2.5 x 10 12 protons per pulse (ppp) with the addition of a new ion source. This intensity is close to the space charge limit of the machine, estimated at approx.3 x 10 12 ppp, depending somewhat on the available aperture. With the present good performance in mind, accelerator improvements are being directed at: (1) increasing beam intensities for neutron science; (2) lowering acceleration losses to minimize activation; and (3) gaining better control of the beam so that losses can be made to occur when and where they can be most easily controlled. On the basis of preliminary measurements, we are now proposing a third cavity for the RF systems which would provide control of the longitudinal bunch shape during the cycle which would permit raising the effective space charge limit of the accelerator and reducing losses

Combined UV-C/H2O2-VUV processes for the treatment of an actual slaughterhouse wastewater.

Science.gov (United States)

Naderi, Kambiz Vaezzadeh; Bustillo-Lecompte, Ciro Fernando; Mehrvar, Mehrab; Abdekhodaie, Mohammad Jafar

2017-05-04

In this study, a three-factor, three-level Box-Behnken design with response surface methodology were used to maximize the TOC removal and minimize the H 2 O 2 residual in the effluent of the combined UV-C/H 2 O 2 -VUV system for the treatment of an actual slaughterhouse wastewater (SWW) collected from one of the meat processing plants in Ontario, Canada. The irradiation time and the initial concentrations of total organic carbon (TOC o ) and hydrogen peroxide (H 2 O 2o ) were the three predictors, as independent variables, studied in the design of experiments. The multiple response approach was used to obtain desirability response surfaces at the optimum factor settings. Subsequently, the optimum conditions to achieve the maximum percentage TOC removal of 46.19% and minimum H 2 O 2 residual of 1.05% were TOC o of 213 mg L -1 , H 2 O 2o of 450 mg L -1 , and irradiation time of 9 min. The attained optimal operating conditions were validated with a complementary test. Consequently, the TOC removal of 45.68% and H 2 O 2 residual of 1.03% were achieved experimentally, confirming the statistical model reliability. Three individual processes, VUV alone, VUV/H 2 O 2 , and UV-C/H 2 O 2 , were also evaluated to compare their performance for the treatment of the actual SWW using the optimum parameters obtained in combined UV-C/H 2 O 2 -VUV processes. Results confirmed that an adequate combination of the UV-C/H 2 O 2 -VUV processes is essential for an optimized TOC removal and H 2 O 2 residual. Finally, respirometry analyses were also performed to evaluate the biodegradability of the SWW and the BOD removal efficiency of the combined UV-C/H 2 O 2 -VUV processes.

Rydberg states of chloroform studied by VUV photoabsorption spectroscopy

Science.gov (United States)

Singh, Param Jeet; Shastri, Aparna; D'Souza, R.; Jagatap, B. N.

2013-11-01

The VUV photoabsorption spectra of CHCl3 and CDCl3 in the energy region 6.2-11.8 eV (50,000-95,000 cm-1) have been investigated using synchrotron radiation from the Indus-1 source. Rydberg series converging to the first four ionization limits at 11.48, 11.91, 12.01 and 12.85 eV corresponding to excitation from the 1a2, 4a1, 4e, 3e, orbitals of CHCl3 respectively are identified and analyzed. Quantum defect values are observed to be consistent with excitation from the chlorine lone pair orbitals. Vibrational progressions observed in the region of 72,500-76,500 cm-1 have been reassigned to ν3 and combination modes of ν3+ν6 belonging to the 1a2→4p transition in contrast to earlier studies where they were assigned to a ν3 progression superimposed on the 3e→4p Rydberg transition. The assignments are further confirmed based on isotopic substitution studies on CDCl3 whose VUV photoabsorption spectrum is reported here for the first time. The frequencies of the ν3 and ν6 modes in the 4p Rydberg state of CHCl3 (CDCl3) are proposed to be ~454 (409) cm-1 and~130 (129) cm-1 respectively based on the vibronic analysis. DFT calculations of neutral and ionic ground state vibrational frequencies support the vibronic analysis. Experimental spectrum is found to be in good agreement with that predicted by TDDFT calculations. This work presents a consolidated analysis of the VUV photoabsorption spectrum of chloroform.

Time-resolved plasma spectroscopy of thin foils heated by a relativistic-intensity short-pulse laser

International Nuclear Information System (INIS)

Audebert, P.; Gauthier, J.-C.; Shepherd, R.; Fournier, K.B.; Price, D.; Lee, R.W.; Springer, P.; Peyrusse, O.; Klein, L.

2002-01-01

Time-resolved K-shell x-ray spectra are recorded from sub-100 nm aluminum foils irradiated by 150-fs laser pulses at relativistic intensities of Iλ 2 =2x10 18 W μm 2 /cm 2 . The thermal penetration depth is greater than the foil thickness in these targets so that uniform heating takes place at constant density before hydrodynamic motion occurs. The high-contrast, high-intensity laser pulse, broad spectral band, and short time resolution utilized in this experiment permit a simplified interpretation of the dynamical evolution of the radiating matter. The observed spectrum displays two distinct phases. At early time, ≤500 fs after detecting target emission, a broad quasicontinuous spectral feature with strong satellite emission from multiply excited levels is seen. At a later time, the He-like resonance line emission is dominant. The time-integrated data is in accord with previous studies with time resolution greater than 1 ps. The early time satellite emission is shown to be a signature of an initial large area, high density, low-temperature plasma created in the foil by fast electrons accelerated by the intense radiation field in the laser spot. We conclude that, because of this early time phenomenon and contrary to previous predictions, a short, high-intensity laser pulse incident on a thin foil does not create a uniform hot and dense plasma. The heating mechanism has been studied as a function of foil thickness, laser pulse length, and intensity. In addition, the spectra are found to be in broad agreement with a hydrodynamic expansion code postprocessed by a collisional-radiative model based on superconfiguration average rates and on the unresolved transition array formalism

Ultra-intense, short pulse laser-plasma interactions with applications to the fast ignitor

Energy Technology Data Exchange (ETDEWEB)

Wilks, S.C.; Kruer, W.L.; Young, P.E.; Hammer, J.; Tabak, M.

1995-04-01

Due to the advent of chirped pulse amplification (CPA) as an efficient means of creating ultra-high intensity laser light (I > 5{times}10{sup 17} W/cm{sup 2}) in pulses less than a few picoseconds, new ideas for achieving ignition and gain in DT targets with less than 1 megajoule of input energy are currently being pursued. Two types of powerful lasers are employed in this scheme: (1) channeling beams and (2) ignition beams. The current state of laser-plasma interactions relating to this fusion scheme will be discussed. In particular, plasma physics issues in the ultra-intense regime are crucial to the success of this scheme. We compare simulation and experimental results in this highly nonlinear regime.

Status of the intense pulsed neutron source

International Nuclear Information System (INIS)

Brown, B.S.; Carpenter, J.M.; Crawford, R.K.; Rauchas, A.V.; Schulke, A.W.; Worlton, T.G.

1989-01-01

Since 1981 the average proton currents at IPNS has increased substantially. The reliability has averaged 91%. The moderator has changed from a room temperature polyethylene to cryogenic methane. This report details progress made at IPNS (Intense Pulsed Neutron Source) during the last two years. The topics discussed are the operating status of the accelerator systems, other accelerator activities (such as, IPNS participation in SDI), instrumentation operating at IPNS, chopper development at IPNS, data acquisition, Booster target, moderators and examples of recent scientific results. The ever increasing instrument capability, the Booster target and the very active involvement with the scientific user community guarantees a productive scientific future at IPNS. 9 figs., 3 tabs

Pulsed x-ray imaging of high-density objects using a ten picosecond high-intensity laser driver

Science.gov (United States)

Rusby, D. R.; Brenner, C. M.; Armstrong, C.; Wilson, L. A.; Clarke, R.; Alejo, A.; Ahmed, H.; Butler, N. M. H.; Haddock, D.; Higginson, A.; McClymont, A.; Mirfayzi, S. R.; Murphy, C.; Notley, M.; Oliver, P.; Allott, R.; Hernandez-Gomez, C.; Kar, S.; McKenna, P.; Neely, D.

2016-10-01

Point-like sources of X-rays that are pulsed (sub nanosecond), high energy (up to several MeV) and bright are very promising for industrial and security applications where imaging through large and dense objects is required. Highly penetrating X-rays can be produced by electrons that have been accelerated by a high intensity laser pulse incident onto a thin solid target. We have used a pulse length of 10ps to accelerate electrons to create a bright x-ray source. The bremsstrahlung temperature was measured for a laser intensity from 8.5-12×1018 W/cm2. These x-rays have sequentially been used to image high density materials using image plate and a pixelated scintillator system.

VUV action spectroscopy of protonated leucine-enkephalin peptide in the 6-14 eV range

Energy Technology Data Exchange (ETDEWEB)

Ranković, M. Lj. [Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade (Serbia); Canon, F. [INRA, UMR1324 Centre des Sciences du Goût et de l’Alimentation, F-21000 Dijon (France); Nahon, L. [SOLEIL, l’Orme des Merisiers, St Aubin, BP48, 91192 Gif sur Yvette Cedex (France); Giuliani, A. [SOLEIL, l’Orme des Merisiers, St Aubin, BP48, 91192 Gif sur Yvette Cedex (France); INRA, UAR1008, CEPIA, Rue de la Géraudière, BP 71627, 44316 Nantes (France); Milosavljević, A. R., E-mail: vraz@ipb.ac.rs [Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade (Serbia); Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

2015-12-28

We have studied the Vacuum Ultraviolet (VUV) photodissociation of gas-phase protonated leucine-enkephalin peptide ion in the 5.7 to 14 eV photon energy range by coupling a linear quadrupole ion trap with a synchrotron radiation source. We report VUV activation tandem mass spectra at 6.7, 8.4, and 12.8 eV photon energies and photodissociation yields for a number of selected fragments. The obtained results provide insight into both near VUV radiation damage and electronic properties of a model peptide. We could distinguish several absorption bands and assign them to particular electronic transitions, according to previous theoretical studies. The photodissociation yields appear to be very different for the various observed fragmentation channels, depending on both the types of fragments and their position along the peptide backbone. The present results are discussed in light of recent gas-phase spectroscopic data on peptides.

Photocathode fatigue of L-24 PM head due to high intensity light pulses

International Nuclear Information System (INIS)

Bailey, K.F.

1980-01-01

The sensitivity of radiation detectors which utilizes photomultipliers was determined after exposing the multiplier phototubes to high intensity light pulses. Test results found that generally less than a 5% change was found

PTB’s radiometric scales for UV and VUV source calibration based on synchrotron radiation

Science.gov (United States)

Klein, Roman; Kroth, Simone; Paustian, Wolfgang; Richter, Mathias; Thornagel, Reiner

2018-06-01

The radiant intensity of synchrotron radiation can be accurately calculated with classical electrodynamics. This primary realization of the spectral radiant intensity has been used by PTB at several electron storage rings which have been optimized to be operated as primary source standards for the calibration of transfer sources in the spectral range of UV and VUV for almost 30 years. The transfer sources are compared to the primary source standard by means of suitable wavelength-dispersive transfer stations. The spectral range covered by deuterium lamps, which represent transfer sources that are easy to handle, is of particular relevance in practice. Here, we report on developments in the realization and preservation of the radiometric scales for spectral radiant intensity and spectral radiance in the wavelength region from 116 nm to 400 nm, based on a set of deuterium reference lamps, over the last few decades. An inside view and recommendations on the operation of the D2 lamps used for the realization of the radiometric scale are presented. The data has been recently compiled to illustrate the chronological behaviour at various wavelengths. Moreover, an overview of the internal and external validation measurements and intercomparisons is given.

Circularly polarized harmonic generation by intense bicircular laser pulses: electron recollision dynamics and frequency dependent helicity

Science.gov (United States)

Bandrauk, André D.; Mauger, François; Yuan, Kai-Jun

2016-12-01

Numerical solutions of time-dependent Schrödinger equations for one and two electron cyclic molecules {{{H}}}nq+ exposed to intense bichromatic circularly polarized laser pulses of frequencies {ω }1 and {ω }2, such that {ω }1/{ω }2={n}1/{n}2 (integer) produce circularly polarized high order harmonics with a cut-off recollision maximum energy at and greater than the linear polarization law (in atomic units) {N}m{ω }1={I}p+3.17{U}p, where I p is the ionization potential and {U}p={(2{E}0)}2/4{ω }2 is the ponderomotive energy defined by the field E 0 (intensity I={{cE}}02/8π ) from each pulse and mean frequency ω =({ω }1+{ω }2)/2 . An electron recollision model in a rotating frame at rotating frequency {{Δ }}ω =({ω }1-{ω }2)/2 predicts this simple result as a result of recollision dynamics in a combination of bichromatic circularly polarized pulses. The harmonic helicities and their intensities are shown to depend on compatible symmetries of the net pulse electric fields with that of the molecules.

Time resolved 3D momentum imaging of ultrafast dynamics by coherent VUV-XUV radiation

Energy Technology Data Exchange (ETDEWEB)

Sturm, F. P., E-mail: fpsturm@lbl.gov [Ultrafast X-Ray Science Lab, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Institut für Kernphysik, Universität Frankfurt, Max-von-Laue Str. 1, D-60438 Frankfurt (Germany); Wright, T. W.; Ray, D.; Zalyubovskaya, I.; Shivaram, N.; Slaughter, D. S.; Belkacem, A.; Weber, Th. [Ultrafast X-Ray Science Lab, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Ranitovic, P. [Ultrafast X-Ray Science Lab, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); ELI-ALPS, ELI-Hu Nkft, Dugonics ter 13, Szeged H6720 (Hungary)

2016-06-15

We present a new experimental setup for measuring ultrafast nuclear and electron dynamics of molecules after photo-excitation and ionization. We combine a high flux femtosecond vacuum ultraviolet (VUV) and extreme ultraviolet (XUV) source with an internally cold molecular beam and a 3D momentum imaging particle spectrometer to measure electrons and ions in coincidence. We describe a variety of tools developed to perform pump-probe studies in the VUV-XUV spectrum and to modify and characterize the photon beam. First benchmark experiments are presented to demonstrate the capabilities of the system.

Low intensity pulsed ultrasound (LIPUS) for bone healing: A clinical practice guideline

NARCIS (Netherlands)

R.W. Poolman (Rudolf); Agoritsas, T. (Thomas); Siemieniuk, R.A.C. (Reed A C); I. Harris (Ian); I.B. Schipper (Inger); Mollon, B. (Brent); Smith, M. (Maureen); Albin, A. (Alexandra); Nador, S. (Sally); Sasges, W. (Will); S. Schandelmaier; Lytvyn, L. (Lyubov); T. Kuijpers (Ton); Van Beers, L.W.A.H. (Loes W A H); M.H.J. Verhofstad (Michiel); P.O. Vandvik (Per)

2017-01-01

textabstractDoes low intensity pulsed ultrasound (LIPUS) accelerate recovery in adults and children who have experienced bone fractures or osteotomy (cutting of a bone)? An expert panel rapidly produced these recommendations based on a linked systematic review triggered by a large multi-centre

The interaction of super-intense ultra-short laser pulse and micro-clusters with large atomic clusters

International Nuclear Information System (INIS)

Miao Jingwei; Yang Chaowen; An Zhu; Yuan Xuedong; Sun Weiguo; Luo Xiaobing; Wang Hu; Bai Lixing; Shi Miangong; Miao Lei; Zhen Zhijian; Gu Yuqin; Liu Hongjie; Zhu Zhouseng; Sun Liwei; Liao Xuehua

2007-01-01

The fusion mechanism of large deuterium clusters (100-1000 Atoms/per cluster) in super-intense ultra-short laser pulse field, Coulomb explosions of micro-cluster in solids, gases and Large-size clusters have been studied using the interaction of a high-intensity femtosecond laser pulses with large deuterium clusters, collision of high-quality beam of micro-cluster from 2.5 MV van de Graaff accelerator with solids, gases and large clusters. The experimental advance of the project is reported. (authors)

Interaction of intense laser pulses with neutral gases and preformed plasmas

International Nuclear Information System (INIS)

Mackinnon, A. J.; Borghesi, M.; Iwase, A.; Jones, M. W.; Willi, O.

1998-01-01

The interaction of a high intensity laser pulse with a neutral gas or preformed plasma has been studied over a wide range of target and laser conditions. It was found that the propagation of 2ps laser pulses (λ=1.054μm, P=5-10TW, I∼5x10 14 -1x10 14 -1x10 18 Wcm -2 ) in neutral gases with atomic densities greater than 0.001 of critical was strongly influenced by ionisation induced refraction. Preformed density channels were effective in overcoming refraction but the channel length was found to be limited by ionization induced defocusing of the prepulse

Current indications and new applications of intense pulsed light.

Science.gov (United States)

González-Rodríguez, A J; Lorente-Gual, R

2015-06-01

Intense pulsed light (IPL) systems have evolved since they were introduced into medical practice 20 years ago. Pulsed light is noncoherent, noncollimated, polychromatic light energy emitted at different wavelengths that target specific chromophores. This selective targeting capability makes IPL a versatile therapy with many applications, from the treatment of pigmented or vascular lesions to hair removal and skin rejuvenation. Its large spot size ensures a high skin coverage rate. The nonablative nature of IPL makes it an increasingly attractive alternative for patients unwilling to accept the adverse effects associated with other procedures, which additionally require prolonged absence from work and social activities. In many cases, IPL is similar to laser therapy in effectiveness, and its versatility, convenience, and safety will lead to an expanded range of applications and possibilities in coming years. Copyright © 2014 Elsevier España, S.L.U. and AEDV. All rights reserved.

Evanescent-wave proton postaccelerator driven by intense THz pulse

OpenAIRE

L. Pálfalvi; J. A. Fülöp; Gy. Tóth; J. Hebling

2014-01-01

Hadron therapy motivates research dealing with the production of particle beams with ∼100  MeV/nucleon energy and relative energy fluctuation on the order of 1%. Laser-driven accelerators produce ion beams with only tens of MeV/nucleon energy and an extremely broad spectra. Here, a novel method is proposed for postacceleration and monochromatization of particles, leaving the laser-driven accelerator, by using intense THz pulses. It is based on further developing the idea of using the evanesce...

Beam intensity increases at the intense pulsed neutron source accelerator

International Nuclear Information System (INIS)

Potts, C.; Brumwell, F.; Norem, J.; Rauchas, A.; Stipp, V.; Volk, G.

1985-01-01

The Intense Pulsed Neutron Source (IPNS) accelerator system has managed a 40% increase in time average beam current over the last two years. Currents of up to 15.6μA (3.25 x 10 12 protons at 30 Hz) have been successfully accelerated and cleanly extracted. Our high current operation demands low loss beam handling to permit hands-on maintenance. Synchrotron beam handling efficiencies of 90% are routine. A new H - ion source which was installed in March of 1983 offered the opportunity to get above 8 μA but an instability caused unacceptable losses when attempting to operate at 10 μA and above. Simple techniques to control the instabilities were introduced and have worked well. These techniques are discussed below. Other improvements in the regulation of various power supplies have provided greatly improved low energy orbit stability and contributed substantially to the increased beam current

Electron Hole Plasma in Solids Induced by Ultrashort XUV Laser Pulses

International Nuclear Information System (INIS)

Rethfeld, B.; Medvedev, N.

2013-01-01

Irradiation of solids with ultrashort XUV laser pulses leads to an excitation of electrons from the valence band and deeper shells to the conduction band leading to a nonequilibrium highly energetic electron hole plasma. We investigate the transient electron dynamics in a solid semiconductor and metal (silicon and aluminum, respectively) under irradiation with a femtosecond VUV to XUV laser pulse as used in experiments with the Free Electron Laser FLASH at DESY in Hamburg, Germany. Applying the Asymptotical Trajectory Monte-Carlo technique, we obtain the transient energy distribution of the excited and ionized electrons within the solid. Photon absorption by electrons in different bands and secondary excitation and ionization processes are simulated event by event. The method was extended in order to take into account the electronic band structure and Pauli's principle for electrons in the conduction band. In this talk we review our results on the dynamics of the transient electron-hole plasma, in particular its transient density and energy distribution in dependence on laser and material parameters. For semiconductors we introduce the concept of an ''effective energy gap'' for collective electronic excitation, which can be applied to estimate the free electron density after high-intensity ultrashort XUV laser pulse irradiation. For aluminum we demonstrate that the electronic spectra depend on the relaxation kinetics of the excited electronic subsystem. Experimentally observed spectra of emitted photons from irradiated aluminum can be explained well with our results. (author)

Intensity stabilisation of optical pulse sequences for coherent control of laser-driven qubits

Science.gov (United States)

Thom, Joseph; Yuen, Ben; Wilpers, Guido; Riis, Erling; Sinclair, Alastair G.

2018-05-01

We demonstrate a system for intensity stabilisation of optical pulse sequences used in laser-driven quantum control of trapped ions. Intensity instability is minimised by active stabilisation of the power (over a dynamic range of > 104) and position of the focused beam at the ion. The fractional Allan deviations in power were found to be logic gates to be below 10^{-6} per gate.

Probing ultrafast dynamics of solid-density plasma generated by high-contrast intense laser pulses

Science.gov (United States)

Jana, Kamalesh; Blackman, David R.; Shaikh, Moniruzzaman; Lad, Amit D.; Sarkar, Deep; Dey, Indranuj; Robinson, Alex P. L.; Pasley, John; Ravindra Kumar, G.

2018-01-01

We present ultrafast dynamics of solid-density plasma created by high-contrast (picosecond contrast ˜10-9), high-intensity (˜4 × 1018 W/cm2) laser pulses using time-resolved pump-probe Doppler spectrometry. Experiments show a rapid rise in blue-shift at early time delay (2-4.3 ps) followed by a rapid fall (4.3-8.3 ps) and then a slow rise in blue-shift at later time delays (>8.3 ps). Simulations show that the early-time observations, specifically the absence of any red-shifting of the reflected probe, can only be reproduced if the front surface is unperturbed by the laser pre-pulse at the moment that the high intensity pulse arrives. A flexible diagnostic which is capable of diagnosing the presence of low-levels of pre-plasma formation would be useful for potential applications in laser-produced proton and ion production, such as cancer therapy and security imaging.

Physics of Neutralization of Intense Charged Particle Beam Pulses by a Background Plasma

International Nuclear Information System (INIS)

Kaganovich, I.D.; Davidson, R.C.; Dorf, M.A.; Startsev, E.A.; Sefkow, A.B; Friedman, A.F.; Lee, E.P.

2009-01-01

Neutralization and focusing of intense charged particle beam pulses by a background plasma forms the basis for a wide range of applications to high energy accelerators and colliders, heavy ion fusion, and astrophysics. For example, for ballistic propagation of intense ion beam pulses, background plasma can be used to effectively neutralize the beam charge and current, so that the self-electric and self-magnetic fields do not affect the ballistic propagation of the beam. From the practical perspective of designing advanced plasma sources for beam neutralization, a robust theory should be able to predict the self-electric and self-magnetic fields during beam propagation through the background plasma. The major scaling relations for the self-electric and self-magnetic fields of intense ion charge bunches propagating through background plasma have been determined taking into account the effects of transients during beam entry into the plasma, the excitation of collective plasma waves, the effects of gas ionization, finite electron temperature, and applied solenoidal and dipole magnetic fields. Accounting for plasma production by gas ionization yields a larger self-magnetic field of the ion beam compared to the case without ionization, and a wake of current density and self-magnetic field perturbations is generated behind the beam pulse. A solenoidal magnetic field can be applied for controlling the beam propagation. Making use of theoretical models and advanced numerical simulations, it is shown that even a small applied magnetic field of about 100G can strongly affect the beam neutralization. It has also been demonstrated that in the presence of an applied magnetic field the ion beam pulse can excite large-amplitude whistler waves, thereby producing a complex structure of self-electric and self-magnetic fields. The presence of an applied solenoidal magnetic field may also cause a strong enhancement of the radial self-electric field of the beam pulse propagating

Photostability studies of prebiotic molecules at the VUV region

International Nuclear Information System (INIS)

Tanaka, H; Medina, A; Mendes, L A V; Prudente, F V; Marinho, R R T; Homem, M G P

2014-01-01

In this work we report absolute cross section studies of prebiotic molecules measured in the VUV range using the double ion chamber technique and synchrotron radiation. Absorption, ionization and neutral decay cross sections will be presented, together with the absolute ionization quantum yield. Additionally, partial ion yield spectra were measured by a TOF mass spectrometer.

Temperature-dependent absorption cross-section measurements of 1-butene (1-C4H8) in VUV and IR

KAUST Repository

Es-sebbar, Et-touhami

2013-01-01

Vacuum ultraviolet (VUV) and infrared (IR) absorption cross-section measurements of 1-butene (1-C4H8; CH2=CHCH2CH3; Butylene) are reported over the temperature range of 296-529K. The VUV measurements are performed between 115 and 205nm using synchrotron radiation as a tunable VUV light source. Fourier Transform Infrared (FTIR) spectroscopy is employed to measure absorption cross-section and band strengths in the IR region between 1.54 and 25μm (~6500-400cm-1). The measured room-temperature VUV and IR absorption cross-sections are compared with available literature data and are found to be in good agreement. The oscillator strength for the electronic transition (A1A\\'→X1A\\') around 150-205nm is determined to be 0.32±0.01.The gas temperature has a strong effect on both VUV and IR spectra. Measurements made in the VUV region show that the peak value of the band cross-section decreases and the background continuum increases with increasing gas temperature. This behavior is due to a change in the rotational and vibrational population distribution of 1-butene molecule. Similar changes in rotational population are observed in the IR spectra. Moreover, variation of the IR spectra with temperature is used to measure the enthalpy difference between syn and skew conformations of 1-butene and is found to be 0.24±0.03. kcal/mol, which is in excellent agreement with values reported in the literature. The measurements reported in this work will provide the much-needed spectroscopic information for the development of high-temperature quantitative diagnostics in combustion applications and validation of atmospheric chemistry models of extra-solar planets. © 2012 Elsevier Ltd.

Side effects from intense pulsed light

DEFF Research Database (Denmark)

Thaysen-Petersen, Daniel; Erlendsson, Andres M; Nash, J F

2017-01-01

BACKGROUND AND OBJECTIVE: Intense pulsed light (IPL) is a mainstream treatment for hair removal. Side effects after IPL are known, but risk factors remain to be investigated. The objective of this study was to assess the contribution of skin pigmentation, fluence level, and ultraviolet radiation...... stacking of 46 J/cm2. Areas were subsequently randomized to no UVR or single solar-simulated UVR exposure of 3 Standard Erythema Dose at 30 minutes or 24 hours after IPL. Each area had a corresponding control, resulting in 15 treatment sites. Follow-up visits were scheduled up to 4 weeks after IPL. Outcome...... measures were: (i) blinded clinical skin reactions; (ii) objectively measured erythema and pigmentation; (iii) pain measured by visual analog scale (VAS); (iv) histology (H&E, Fontana-Masson); and (v) mRNA-expression of p53. RESULTS: Fifteen subjects with FST II-IV completed the protocol. IPL induced...

Electromagnetic cascade in high-energy electron, positron, and photon interactions with intense laser pulses

Science.gov (United States)

Bulanov, S. S.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.

2013-06-01

The interaction of high-energy electrons, positrons, and photons with intense laser pulses is studied in head-on collision geometry. It is shown that electrons and/or positrons undergo a cascade-type process involving multiple emissions of photons. These photons can consequently convert into electron-positron pairs. As a result charged particles quickly lose their energy developing an exponentially decaying energy distribution, which suppresses the emission of high-energy photons, thus reducing the number of electron-positron pairs being generated. Therefore, this type of interaction suppresses the development of the electromagnetic avalanche-type discharge, i.e., the exponential growth of the number of electrons, positrons, and photons does not occur in the course of interaction. The suppression will occur when three-dimensional effects can be neglected in the transverse particle orbits, i.e., for sufficiently broad laser pulses with intensities that are not too extreme. The final distributions of electrons, positrons, and photons are calculated for the case of a high-energy e-beam interacting with a counterstreaming, short intense laser pulse. The energy loss of the e-beam, which requires a self-consistent quantum description, plays an important role in this process, as well as provides a clear experimental observable for the transition from the classical to quantum regime of interaction.

HiRadMat at CERN/SPS - A dedicated facility providing high intensity beam pulses to material samples

CERN Multimedia

Charitonidis, N; Efthymiopoulos, I

2014-01-01

HiRadMat (High Radiation to Materials), constructed in 2011, is a facility at CERN designed to provide high‐intensity pulsed beams to an irradiation area where material samples as well as accelerator component assemblies (e.g. vacuum windows, high power beam targets, collimators…) can be tested. The facility uses a 440 GeV proton beam extracted from the CERN SPS with a pulse length of up to 7.2 us, and with a maximum pulse energy of 3.4 MJ (3xE13 proton/pulse). In addition to protons, ion beams with energy of 440 GeV/charge and total pulse energy of 21 kJ can be provided. The beam parameters can be tuned to match the needs of each experiment. HiRadMat is not an irradiation facility where large doses on equipment can be accumulated. It is rather a test area designed to perform single pulse experiments to evaluate the effect of high‐intensity pulsed beams on materials or accelerator component assemblies in a controlled environment. The fa‐ cility is designed for a maximum of 1E16 protons per year, dist...

Area radiation monitor at the intense pulsed-neutron source

International Nuclear Information System (INIS)

Eichholz, J.J.; Lynch, F.J.; Mundis, R.L.; Howe, M.L.; Dolecek, E.H.

1981-01-01

A tissue-equivalent ionization chamber with associated circuitry has been developed for area radiation monitoring in the Intense Pulsed-Neutron Source (IPNS) facility at Argonne National Laboratory. The conventional chamber configuration was modified in order to increase the electric field and effective volume thereby achieving higher sensitivity and linearity. The instrument provides local and remote radiation level indications and a high level alarm. Twenty-four of these instruments were fabricated for use at various locations in the experimental area of the IPNS-1 facility

Interaction of ultra-short ultra-intense laser pulses with under-dense plasmas; Interaction d'impulsions laser ultra-courtes et ultra-intenses avec des plasmas sous denses

Energy Technology Data Exchange (ETDEWEB)

Solodov, A

2000-12-15

Different aspects of interaction of ultra-short ultra-intense laser pulses with underdense plasmas are studied analytically and numerically. These studies can be interesting for laser-driven electron acceleration in plasma, X-ray lasers, high-order harmonic generation, initial confinement fusion with fast ignition. For numerical simulations a fully-relativistic particle code WAKE was used, developed earlier at Ecole Polytechnique. It was modified during the work on the thesis in the part of simulation of ion motion, test electron motion, diagnostics for the field and plasma. The studies in the thesis cover the problems of photon acceleration in the plasma wake of a short intense laser pulse, phase velocity of the plasma wave in the Self-Modulated Laser Wake-Field Accelerator (SM LWFA), relativistic channeling of laser pulses with duration of the order of a plasma period, ion dynamics in the wake of a short intense laser pulse, plasma wave breaking. Simulation of three experiments on the laser pulse propagation in plasma and electron acceleration were performed. Among the main results of the thesis, it was found that reduction of the plasma wave phase velocity in the SM LWFA is crucial for electron acceleration, only if a plasma channel is used for the laser pulse guiding. Self-similar structures describing relativistic guiding of short laser pulses in plasmas were found and relativistic channeling of initially Gaussian laser pulses of a few plasma periods in duration was demonstrated. It was shown that ponderomotive force of a plasma wake excited by a short laser pulse forms a channel in plasma and plasma wave breaking in the channel was analyzed in detail. Effectiveness of electron acceleration by the laser field and plasma wave was compared and frequency shift of probe laser pulses by the plasma waves was found in conditions relevant to the current experiments. (author)

Interaction of ultra-high intensity laser pulse with a mass limited targets

International Nuclear Information System (INIS)

Andreev, A.A.; Platonov, K.Yu.; Limpouch, J.; Psikal, J.; Kawata, S.

2006-01-01

Complete test of publication follows. Ultra-high intensity laser pulses may be produced now via CPA scheme by using very short laser pulses of a relatively low energy. Interaction of such pulses with massive target is not very efficient as the energy delivered to charged particles spreads out quickly over large distances and it is redistributed between many secondary particles. One possibility to limit this undesirable energy spread is to use mass limited targets (MLT), for example droplets, big clusters or small foil sections. This is an intermediate regime in target dimensions between bulk solid and nanometer-size atomic cluster targets. A few experimental and theoretical studies have been carried out on laser absorption, fast particle generation and induced nuclear fusion reactions in the interaction of ultrashort laser pulses with MLT plasma. We investigate here laser interactions with MLT via 2D3V relativistic electromagnetic PIC simulations. We assume spherical droplet as a typical MLT. However, the sphere is represented in 2D simulations by an infinite cylinder irradiated uniformly along its length. We assume that MLT is fully ionized before main pulse interaction either due to insufficient laser contrast or due to a prepulse. For simplicity, we assume homogeneous plasma of high initial temperature. We analyze the interaction of relativistic laser pulses of various polarizations with targets of different shapes, such as a foil, quadrant and sphere. The mechanisms of laser absorption, electron and ion acceleration are clarified for different laser and target parameters. When laser interacts with the target front side, kinetic energy of electrons rises rapidly with fast oscillations in the kinetic and field energy, caused by electron oscillations in the laser field. Small energy oscillations, observed later, are caused by the electron motion back and forth through the droplet. Approximately 40% of laser energy is transferred to the kinetic energy of electrons

Effect of intense pulsed light on immature burn scars: A clinical study

Directory of Open Access Journals (Sweden)

Arindam Sarkar

2014-01-01

Full Text Available Introduction: As intense pulsed light (IPL is widely used to treat cutaneous vascular malformations and also used as non-ablative skin rejunuvation to remodel the skin collagen. A study has been undertaken to gauze the effect of IPL on immature burn scars with regard to vascularity, pliability and height. Materials and Methods: This study was conducted between June 2013 and May 2014, among patients with immature burn scars that healed conservatively within 2 months. Photographic evidence of appearance of scars and grading and rating was done with Vancouver Scar Scale parameters. Ratings were done for both case and control scar after the completion of four IPL treatment sessions and were compared. Results: Out of the 19 cases, vascularity, pliability and height improved significantly (P < 0.05 in 13, 14 and 11 scars respectively following IPL treatment. Conclusions: Intense pulsed light was well-tolerated by patients, caused good improvement in terms of vascularity, pliability, and height of immature burn scar.

Phase Noise and Intensity Noise of the Pulse Train Generated from Mode-locked Lasers in the Demodulation Measurement

OpenAIRE

Wu, Kan; Shum, Ping

2010-01-01

The phase noise and intensity noise of a pulse train are theoretically analyzed in the demodulation measurement. The effect of pulse asymmetry is discussed for the first time using Fourier series. Experimentally, photodetectors with different bandwidth and incident power levels are compared to achieve minimum pulse distortion.

A transparent vacuum window for high-intensity pulsed beams

CERN Document Server

Monteil, M; Veness, R

2011-01-01

The HiRadMat (High-Radiation to Materials) facility Ill will allow testing of accelerator components, in particular those of the Large Hadron Collider (LHC) at CERN, under the impact of high-intensity pulsed beams. To reach this intensity range, the beam will be focused on a focal point where the target to be tested is located. A 60 mm aperture vacuum window will separate the vacuum of the beam line which is kept under high vacuum 10(-8) mbar, from the test area which is at atmospheric pressure. This window has to resist collapse due to beam passage. The high-intensity of the beam means that typical materials used for standard vacuum windows (such as stainless steel, aluminium and titanium alloy) cannot endure the energy deposition induced by the beam passage. Therefore, a vacuum window has been designed to maintain the differential pressure whilst resisting collapse due to the beam impact on the window. In this paper, we will present calculations of the energy transfer from beam to window, the design of the ...

Experience with the UHV box coater and the evaporation procedure for VUV reflective coatings on the HADES RICH mirror

CERN Document Server

Maier-Komor, P; Wieser, J; Ulrich, A

1999-01-01

An UHV box coater was set up for the deposition of highly reflective layers in the vacuum ultraviolet (VUV) wavelength range on large-area mirror substrates. The VUV mirrors are needed for the ring imaging Cherenkov (RICH) detector of the high-acceptance di-electron spectrometer (HADES). The complete dry vacuum system is described. The spatial deposition distribution from the evaporation sources was measured. The reflectivity of the Al mirror layer was optimized for the wavelength range of 145-210 nm by varying the thickness of the MgF sub 2 protective layer. The setup for measuring the reflectivity in the VUV range is described and reflectivity data are presented.

Electron Acceleration and the Propagation of Ultrashort High-Intensity Laser Pulses in Plasmas

International Nuclear Information System (INIS)

Wang, Xiaofang; Krishnan, Mohan; Saleh, Ned; Wang, Haiwen; Umstadter, Donald

2000-01-01

Reported are interactions of high-intensity laser pulses (λ=810 nm and I≤3x10 18 W /cm 2 ) with plasmas in a new parameter regime, in which the pulse duration (τ=29 fs ) corresponds to 0.6-2.6 plasma periods. Relativistic filamentation is observed to cause laser-beam breakup and scattering of the beam out of the vacuum propagation angle. A beam of megaelectronvolt electrons with divergence angle as small as 1 degree sign is generated in the forward direction, which is correlated to the growth of the relativistic filamentation. Raman scattering, however, is found to be much less than previous long-pulse results. (c) 2000 The American Physical Society

VUV photo-processing of PAH cations: quantitative study on the ionization versus fragmentation processes.

Science.gov (United States)

Zhen, Junfeng; Castillo, Sarah Rodriguez; Joblin, Christine; Mulas, Giacomo; Sabbah, Hassan; Giuliani, Alexandre; Nahon, Laurent; Martin, Serge; Champeaux, Jean-Philippe; Mayer, Paul M

2016-05-10

Interstellar polycyclic aromatic hydrocarbons (PAHs) are strongly affected by the absorption of vacuum ultraviolet (VUV) photons in the interstellar medium (ISM), yet the branching ratio between ionization and fragmentation is poorly studied. This is crucial for the stability and charge state of PAHs in the ISM in different environments, affecting in turn the chemistry, the energy balance, and the contribution of PAHs to the extinction and emission curves. We studied the interaction of PAH cations with VUV photons in the 7 - 20 eV range from the synchrotron SOLEIL beamline, DESIRS. We recorded by action spectroscopy the relative intensities of photo-fragmentation and photo-ionization for a set of eight PAH cations ranging in size from 14 to 24 carbon atoms, with different structures. At photon energies below ~13.6 eV fragmentation dominates for the smaller species, while for larger species ionization is immediately competitive after the second ionization potential (IP). At higher photon energies, all species behave similarly, the ionization yield gradually increases, leveling off between 0.8 and 0.9 at ~18 eV. Among isomers, PAH structure appears to mainly affect the fragmentation cross section, but not the ionization cross section. We also measured the second IP for all species and the third IP for two of them, all are in good agreement with theoretical ones confirming that PAH cations can be further ionized in the diffuse ISM. Determining actual PAH dication abundances in the ISM will require detailed modeling. Our measured photo-ionization yields for several PAH cations provide a necessary ingredient for such models.

VUV PHOTO-PROCESSING OF PAH CATIONS: QUANTITATIVE STUDY ON THE IONIZATION VERSUS FRAGMENTATION PROCESSES

Energy Technology Data Exchange (ETDEWEB)

Zhen, Junfeng; Castillo, Sarah Rodriguez; Joblin, Christine; Mulas, Giacomo; Sabbah, Hassan [Université de Toulouse, UPS-OMP, Institut de Recherche en Astrophysique et Planétologie, Toulouse (France); Giuliani, Alexandre; Nahon, Laurent [Synchrotron SOLEIL, LOrme des Merisiers, F-91192 Gif sur Yvette Cedex (France); Martin, Serge [Institut Lumière Matière, Université Lyon 1-CNRS, Université de Lyon, F-69622 Villeurbanne cedex (France); Champeaux, Jean-Philippe [Laboratoire Collisions Agrégats Réactivité, Université de Toulouse, UPS-IRSAMC, CNRS, 118 Route de Narbonne, Bat 3R1B4, F-31062 Toulouse Cedex 9 (France); Mayer, Paul M., E-mail: christine.joblin@irap.omp.eu [Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa K1N 6N5 (Canada)

2016-05-10

Interstellar polycyclic aromatic hydrocarbons (PAHs) are strongly affected by the absorption of vacuum ultraviolet (VUV) photons in the interstellar medium (ISM), yet the branching ratio between ionization and fragmentation is poorly studied. This is crucial for the stability and charge state of PAHs in the ISM in different environments, affecting in turn the chemistry, the energy balance, and the contribution of PAHs to the extinction and emission curves. We studied the interaction of PAH cations with VUV photons in the 7–20 eV range from the synchrotron SOLEIL beamline, DESIRS. We recorded by action spectroscopy the relative intensities of photo-fragmentation and photo-ionization for a set of eight PAH cations ranging in size from 14 to 24 carbon atoms, with different structures. At photon energies below ∼13.6 eV fragmentation dominates for the smaller species, while for larger species ionization is immediately competitive after the second ionization potential (IP). At higher photon energies all species behave similarly; the ionization yield gradually increases, leveling off between 0.8 and 0.9 at ∼18 eV. Among isomers, PAH structure appears to mainly affect the fragmentation cross section but not the ionization cross section. We also measured the second IP for all species and the third IP for two of them; all are in good agreement with theoretical ones, confirming that PAH cations can be further ionized in the diffuse ISM. Determining actual PAH dication abundances in the ISM will require detailed modeling. Our measured photo-ionization yields for several PAH cations provide a necessary ingredient for such models.

VUV PHOTO-PROCESSING OF PAH CATIONS: QUANTITATIVE STUDY ON THE IONIZATION VERSUS FRAGMENTATION PROCESSES

International Nuclear Information System (INIS)

Zhen, Junfeng; Castillo, Sarah Rodriguez; Joblin, Christine; Mulas, Giacomo; Sabbah, Hassan; Giuliani, Alexandre; Nahon, Laurent; Martin, Serge; Champeaux, Jean-Philippe; Mayer, Paul M.

2016-01-01

Interstellar polycyclic aromatic hydrocarbons (PAHs) are strongly affected by the absorption of vacuum ultraviolet (VUV) photons in the interstellar medium (ISM), yet the branching ratio between ionization and fragmentation is poorly studied. This is crucial for the stability and charge state of PAHs in the ISM in different environments, affecting in turn the chemistry, the energy balance, and the contribution of PAHs to the extinction and emission curves. We studied the interaction of PAH cations with VUV photons in the 7–20 eV range from the synchrotron SOLEIL beamline, DESIRS. We recorded by action spectroscopy the relative intensities of photo-fragmentation and photo-ionization for a set of eight PAH cations ranging in size from 14 to 24 carbon atoms, with different structures. At photon energies below ∼13.6 eV fragmentation dominates for the smaller species, while for larger species ionization is immediately competitive after the second ionization potential (IP). At higher photon energies all species behave similarly; the ionization yield gradually increases, leveling off between 0.8 and 0.9 at ∼18 eV. Among isomers, PAH structure appears to mainly affect the fragmentation cross section but not the ionization cross section. We also measured the second IP for all species and the third IP for two of them; all are in good agreement with theoretical ones, confirming that PAH cations can be further ionized in the diffuse ISM. Determining actual PAH dication abundances in the ISM will require detailed modeling. Our measured photo-ionization yields for several PAH cations provide a necessary ingredient for such models.

VUV photo-processing of PAH cations: quantitative study on the ionization versus fragmentation processes

Science.gov (United States)

Zhen, Junfeng; Castillo, Sarah Rodriguez; Joblin, Christine; Mulas, Giacomo; Sabbah, Hassan; Giuliani, Alexandre; Nahon, Laurent; Martin, Serge; Champeaux, Jean-Philippe; Mayer, Paul M.

2016-01-01

Interstellar polycyclic aromatic hydrocarbons (PAHs) are strongly affected by the absorption of vacuum ultraviolet (VUV) photons in the interstellar medium (ISM), yet the branching ratio between ionization and fragmentation is poorly studied. This is crucial for the stability and charge state of PAHs in the ISM in different environments, affecting in turn the chemistry, the energy balance, and the contribution of PAHs to the extinction and emission curves. We studied the interaction of PAH cations with VUV photons in the 7 – 20 eV range from the synchrotron SOLEIL beamline, DESIRS. We recorded by action spectroscopy the relative intensities of photo-fragmentation and photo-ionization for a set of eight PAH cations ranging in size from 14 to 24 carbon atoms, with different structures. At photon energies below ~13.6 eV fragmentation dominates for the smaller species, while for larger species ionization is immediately competitive after the second ionization potential (IP). At higher photon energies, all species behave similarly, the ionization yield gradually increases, leveling off between 0.8 and 0.9 at ~18 eV. Among isomers, PAH structure appears to mainly affect the fragmentation cross section, but not the ionization cross section. We also measured the second IP for all species and the third IP for two of them, all are in good agreement with theoretical ones confirming that PAH cations can be further ionized in the diffuse ISM. Determining actual PAH dication abundances in the ISM will require detailed modeling. Our measured photo-ionization yields for several PAH cations provide a necessary ingredient for such models. PMID:27212712

Zero photon dissociation of CS2+ in intense ultrashort laser pulses

Science.gov (United States)

Severt, Travis; Betsch, K. J.; Zohrabi, M.; Ablikim, U.; Jochim, Bethany; Carnes, K. D.; Esry, B. D.; Ben-Itzhak, I.

2013-05-01

We measured the dissociation of a CS2+ molecular ion beam in intense laser pulses ( C+ + S+. We speculate that a pump-dump process occurs whereby the vibrational wavepacket in the electronic ground state of CS2+ is pumped into the electronic first excited state's continuum by a single photon during the laser pulse. Once this continuum vibrational wavepacket passes the potential barrier in the ground electronic potential, the emission of a second photon is stimulated by the same laser pulse, most likely when the wavepacket moves through the internuclear distance where the two electronic states are in resonance with the driving field. A comparison is made to ZPD and ATD in the isovalent CO2+ species. Curiously, ATD is the favored mechanism in CO2+. The underlying molecular structure and dynamics determining this preference will be discussed. Supported by Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy.

Multi-pulsed intense electron beam emission from velvet, carbon fibers, carbon nano-tubes and dispenser cathodes

International Nuclear Information System (INIS)

Xia Liansheng; Yang Anmin; Chen Yi; Zhang Huang; Liu Xingguang; Li Jin; Jiang Xiaoguo; Zhang Kaizhi; Shi Jinshui; Deng Jianjun; Zhang Linwen

2010-01-01

The experimental results of studies of four kinds of cathode emitting intense electron beams are demonstrated under multi-pulsed mode based on an experimental setup including two multi-pulse high voltage sources. The tested cathodes include velvet, carbon fibers, carbon nano-tubes (CNTs) and dispenser cathodes. The results indicate that all four are able to emit multi-pulsed beams. For velvet, carbon fiber and CNTs, the electron induced cathode plasma emission may be the main process and this means that there are differences in beam parameters from pulse to pulse. For dispenser cathodes tested in the experiment, although there is a little difference from pulse to pulse for some reason, thermal-electric field emission may be the main process. (authors)

Nonsequential double ionization of D2 molecules with intense 20-fs pulses

DEFF Research Database (Denmark)

Sakai, H.; Larsen, J.J.; Wendt-Larsen, I.

2003-01-01

The kinetic-energy distribution of D+ fragments obtained from the ionization of D2 molecules with intense 20-fs pulses includes a high-energy component extending up to ˜10 eV. These fragments are only present for linearly, or slightly elliptically, polarized light. Both the maximum kinetic...

Microjet formation and hard x-ray production from a liquid metal target irradiated by intense femtosecond laser pulses

Energy Technology Data Exchange (ETDEWEB)

Lar' kin, A., E-mail: alexeylarkin@yandex.ru; Uryupina, D.; Ivanov, K.; Savel' ev, A., E-mail: abst@physics.msu.ru [International Laser Center and Faculty of Physics, Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Bonnet, T.; Gobet, F.; Hannachi, F.; Tarisien, M.; Versteegen, M. [Centre d' Études Nucléaires de Bordeaux-Gradignan, University of Bordeaux-CNRS-IN2P3, 33170 Gradignan (France); Spohr, K. [School of Engineering, University of the West of Scotland, Paisley, Scotland PA1 2BE (United Kingdom); Breil, J.; Chimier, B.; Dorchies, F.; Fourment, C.; Leguay, P.-M.; Tikhonchuk, V. T. [Centre Lasers Intenses et Applications, University of Bordeaux-CNRS-CEA, Talence 33405 (France)

2014-09-15

By using a liquid metal as a target one may significantly enhance the yield of hard x-rays with a sequence of two intense femtosecond laser pulses. The influence of the time delay between the two pulses is studied experimentally and interpreted with numerical simulations. It was suggested that the first arbitrary weak pulse produces microjets from the target surface, while the second intense pulse provides an efficient electron heating and acceleration along the jet surface. These energetic electrons are the source of x-ray emission while striking the target surface. The microjet formation is explained based on the results given by both optical diagnostics and hydrodynamic modeling by a collision of shocks originated from two distinct zones of laser energy deposition.

Microjet formation and hard x-ray production from a liquid metal target irradiated by intense femtosecond laser pulses

International Nuclear Information System (INIS)

Lar'kin, A.; Uryupina, D.; Ivanov, K.; Savel'ev, A.; Bonnet, T.; Gobet, F.; Hannachi, F.; Tarisien, M.; Versteegen, M.; Spohr, K.; Breil, J.; Chimier, B.; Dorchies, F.; Fourment, C.; Leguay, P.-M.; Tikhonchuk, V. T.

2014-01-01

By using a liquid metal as a target one may significantly enhance the yield of hard x-rays with a sequence of two intense femtosecond laser pulses. The influence of the time delay between the two pulses is studied experimentally and interpreted with numerical simulations. It was suggested that the first arbitrary weak pulse produces microjets from the target surface, while the second intense pulse provides an efficient electron heating and acceleration along the jet surface. These energetic electrons are the source of x-ray emission while striking the target surface. The microjet formation is explained based on the results given by both optical diagnostics and hydrodynamic modeling by a collision of shocks originated from two distinct zones of laser energy deposition

Microjet formation and hard x-ray production from a liquid metal target irradiated by intense femtosecond laser pulses

Science.gov (United States)

Lar'kin, A.; Uryupina, D.; Ivanov, K.; Savel'ev, A.; Bonnet, T.; Gobet, F.; Hannachi, F.; Tarisien, M.; Versteegen, M.; Spohr, K.; Breil, J.; Chimier, B.; Dorchies, F.; Fourment, C.; Leguay, P.-M.; Tikhonchuk, V. T.

2014-09-01

By using a liquid metal as a target one may significantly enhance the yield of hard x-rays with a sequence of two intense femtosecond laser pulses. The influence of the time delay between the two pulses is studied experimentally and interpreted with numerical simulations. It was suggested that the first arbitrary weak pulse produces microjets from the target surface, while the second intense pulse provides an efficient electron heating and acceleration along the jet surface. These energetic electrons are the source of x-ray emission while striking the target surface. The microjet formation is explained based on the results given by both optical diagnostics and hydrodynamic modeling by a collision of shocks originated from two distinct zones of laser energy deposition.

The VUV instrument SPICE for Solar Orbiter: performance ground testing

Science.gov (United States)

Caldwell, Martin E.; Morris, Nigel; Griffin, Douglas K.; Eccleston, Paul; Anderson, Mark; Pastor Santos, Carmen; Bruzzi, Davide; Tustain, Samuel; Howe, Chris; Davenne, Jenny; Grundy, Timothy; Speight, Roisin; Sidher, Sunil D.; Giunta, Alessandra; Fludra, Andrzej; Philippon, Anne; Auchere, Frederic; Hassler, Don; Davila, Joseph M.; Thompson, William T.; Schuehle, Udo H.; Meining, Stefan; Walls, Buddy; Phelan, P.; Dunn, Greg; Klein, Roman M.; Reichel, Thomas; Gyo, Manfred; Munro, Grant J.; Holmes, William; Doyle, Peter

2017-08-01

SPICE is an imaging spectrometer operating at vacuum ultraviolet (VUV) wavelengths, 70.4 - 79.0 nm and 97.3 - 104.9 nm. It is a facility instrument on the Solar Orbiter mission, which carries 10 science instruments in all, to make observations of the Sun's atmosphere and heliosphere, at close proximity to the Sun, i.e to 0.28 A.U. at perihelion. SPICE's role is to make VUV measurements of plasma in the solar atmosphere. SPICE is designed to achieve spectral imaging at spectral resolution >1500, spatial resolution of several arcsec, and two-dimensional FOV of 11 x16arcmins. The many strong constraints on the instrument design imposed by the mission requirements prevent the imaging performance from exceeding those of previous instruments, but by being closer to the sun there is a gain in spatial resolution. The price which is paid is the harsher environment, particularly thermal. This leads to some novel features in the design, which needed to be proven by ground test programs. These include a dichroic solar-transmitting primary mirror to dump the solar heat, a high in-flight temperature (60deg.C) and gradients in the optics box, and a bespoke variable-line-spacing grating to minimise the number of reflective components used. The tests culminate in the systemlevel test of VUV imaging performance and pointing stability. We will describe how our dedicated facility with heritage from previous solar instruments, is used to make these tests, and show the results, firstly on the Engineering Model of the optics unit, and more recently on the Flight Model. For the keywords, select up to 8 key terms for a search on your manuscript's subject.

VUV photoionization cross sections of HO2, H2O2, and H2CO.

Science.gov (United States)

Dodson, Leah G; Shen, Linhan; Savee, John D; Eddingsaas, Nathan C; Welz, Oliver; Taatjes, Craig A; Osborn, David L; Sander, Stanley P; Okumura, Mitchio

2015-02-26

The absolute vacuum ultraviolet (VUV) photoionization spectra of the hydroperoxyl radical (HO2), hydrogen peroxide (H2O2), and formaldehyde (H2CO) have been measured from their first ionization thresholds to 12.008 eV. HO2, H2O2, and H2CO were generated from the oxidation of methanol initiated by pulsed-laser-photolysis of Cl2 in a low-pressure slow flow reactor. Reactants, intermediates, and products were detected by time-resolved multiplexed synchrotron photoionization mass spectrometry. Absolute concentrations were obtained from the time-dependent photoion signals by modeling the kinetics of the methanol oxidation chemistry. Photoionization cross sections were determined at several photon energies relative to the cross section of methanol, which was in turn determined relative to that of propene. These measurements were used to place relative photoionization spectra of HO2, H2O2, and H2CO on an absolute scale, resulting in absolute photoionization spectra.

Pulsed neutron source very intense, Booster

International Nuclear Information System (INIS)

Abbate, J.M.

1978-09-01

A compact Accelerator-Booster (fast, pulsed and modulate reactivity research reactor) is a new and appropriate conception to use as a very intense thermal neutrons source. Its definition and feasibility have been already described in several studies showing its relative advantages in comparison with others kinds of facilities. This work, wich is part of one of those studies, contains a general analysis on the meis facility parameters and core and shielding theoretical calculations. The following results were obtained: Selection and test of a calculation system suitable to use in compact fast reactors; Development a method to perform estimations in some safety and shielding problems and obtainment of adequate theoretical predictions on the general performance. Moreover, final results for importent parameters of the feasibility study and predesign (critical mass and volume, lifetime, etc.) and others related to the use of plutonium oxide as fuel are given and then evaluations of different basic functions are showed. (author) [es

Study of intense pulse irradiation effects on silicon targets considered as ground matter for optical detectors

International Nuclear Information System (INIS)

Muller, O.

1994-12-01

This study aim was centered on morphological and structural alterations induced by laser irradiation on silicon targets considered as ground matter for optical detectors. First we recalled the main high light intensity effects on the condensed matter. Then we presented the experimental aspects. The experimental studies were achieved on two sample types: SiO 2 /Si and Si. Two topics were studied: the defect chronology according to wavelength and pulse length, and the crystalline quality as well as the structure defects of irradiated zones by Raman spectroscopy. Finally, irradiation of Si targets by intense pulsed beams may lead to material fusion. This phenomenon is particularly easy when the material is absorbent, when the pulse is short and when the material is superficially oxidized. (MML). 204 refs., 93 figs., 21 tabs., 1 appendix

ILIAS. Ion and laser beam interaction and application studies. Progress report no. 3 of the PHELIX theory group

Energy Technology Data Exchange (ETDEWEB)

Mulser, P. (ed.)

2008-04-15

The following topics are dealt with: The PHELIX laser-plasma facility, coupling of nuclear matter to intense photon fields, QED effects in strong laser fields, relativistic critical density increase in a linearly polarized laser beam, absorption of ultrashort laser pulses in strongly overdense targets, Coulomb focusing in electron-ion collisions in a strong laser field, quasiperiodic waves in relativistic plasmas, high-energy-density physics studied by intense particle beams, heavy ions in a high-power laser beam, Monte-Carlo study of electron dynamics in silicon during irradiation with an ultrashort VUV laser pulse. (HSI)

ILIAS. Ion and laser beam interaction and application studies. Progress report no. 3 of the PHELIX theory group

International Nuclear Information System (INIS)

Mulser, P.

2008-04-01

The following topics are dealt with: The PHELIX laser-plasma facility, coupling of nuclear matter to intense photon fields, QED effects in strong laser fields, relativistic critical density increase in a linearly polarized laser beam, absorption of ultrashort laser pulses in strongly overdense targets, Coulomb focusing in electron-ion collisions in a strong laser field, quasiperiodic waves in relativistic plasmas, high-energy-density physics studied by intense particle beams, heavy ions in a high-power laser beam, Monte-Carlo study of electron dynamics in silicon during irradiation with an ultrashort VUV laser pulse. (HSI)

Extraction of a long-pulsed intense electron beam from a pulsed plasma based on hollow cathode discharge

International Nuclear Information System (INIS)

Uramoto, Johshin.

1977-05-01

An intense electron beam (up to 1.0 kV, 0.8 kA in 0.8 cm phi) is extracted along a uniform magnetic field with a long decay time (up to 2 msec) from a pulsed high density plasma source which is produced with a fast rise time (< 100 μsec) by a secondary discharge based on a dc hollow cathode discharge. Through a back stream of ionized ions from a beam-extracting anode region where a neutral gas is fed, a space charge limit of the electron beam is so reduced that the beam current is determined by an initially injected electron flux and concentrated in a central aperture of the extracting anode. Moreover, the beam pulse width is much extended by the neutral gas feed into the anode space. (auth.)

Self-Guiding of Ultrashort Relativistically Intense Laser Pulses to the Limit of Nonlinear Pump Depletion

International Nuclear Information System (INIS)

Ralph, J. E.; Marsh, K. A.; Pak, A. E.; Lu, W.; Clayton, C. E.; Fang, F.; Joshi, C.; Tsung, F. S.; Mori, W. B.

2009-01-01

A study of self-guiding of ultra short, relativistically intense laser pulses is presented. Here, the laser pulse length is on the order of the nonlinear plasma wavelength and the normalized vector potential is greater than one. Self-guiding of ultrashort laser pulses over tens of Rayliegh lengths is possible when driving a highly nonlinear wake. In this case, self-guiding is limited by nonlinear pump depletion. Erosion of the pulse due to diffraction at the head of the laser pulse is minimized for spot sizes close to the blow-out radius. This is due to the slowing of the group velocity of the photons at the head of the laser pulse. Using an approximately 10 TW Ti:Sapphire laser with a pulse length of approximately 50 fs, experimental results are presented showing self-guiding over lengths exceeding 30 Rayliegh lengths in various length Helium gas jets. Fully explicit 3D PIC simulations supporting the experimental results are also presented.

Guiding of short, intense laser pulses through solid guides and preformed plasma channels

International Nuclear Information System (INIS)

Borghesi, M.; Mackinnon, A.J.; Gaillard, R.; Malka, G.; Vickers, C.; Willi, O.; Blanchot, N.; Miquel, J.L.; Canaud, B.; Davies, J.R.; Malka, G.; Offenberger, A.A.

2000-01-01

In a series of experiments carried out at the Rutherford Appleton Laboratory, Chilton (UK) and at the Commissariat a l'Energie Atomique, Limeil (France), various techniques of guiding ultra-intense laser pulses over distances exceeding the natural diffraction length were investigated. Efficient guiding was demonstrated both through density channels formed in an underdense plasma by an intense prepulse and through solid guides (hollow capillary tubes). Indication of collimated fast electron propagation though solid targets has also been obtained. (authors)

Numerical studies of acceleration of thorium ions by a laser pulse of ultra-relativistic intensity

Directory of Open Access Journals (Sweden)

Domanski Jaroslaw

2018-01-01

Full Text Available One of the key scientific projects of ELI-Nuclear Physics is to study the production of extremely neutron-rich nuclides by a new reaction mechanism called fission-fusion using laser-accelerated thorium (232Th ions. This research is of crucial importance for understanding the nature of the creation of heavy elements in the Universe; however, they require Th ion beams of very high beam fluencies and intensities which are inaccessible in conventional accelerators. This contribution is a first attempt to investigate the possibility of the generation of intense Th ion beams by a fs laser pulse of ultra-relativistic intensity. The investigation was performed with the use of fully electromagnetic relativistic particle-in-cell code. A sub-μm thorium target was irradiated by a circularly polarized 20-fs laser pulse of intensity up to 1023 W/cm2, predicted to be attainable at ELI-NP. At the laser intensity ~ 1023 W/cm2 and an optimum target thickness, the maximum energies of Th ions approach 9.3 GeV, the ion beam intensity is > 1020 W/cm2 and the total ion fluence reaches values ~ 1019 ions/cm2. The last two values are much higher than attainable in conventional accelerators and are fairly promising for the planned ELI-NP experiment.

Intense microwave pulses II. SPIE Volume 2154

International Nuclear Information System (INIS)

Brandt, H.E.

1994-01-01

The primary purpose of this conference was to present and critically evaluate new and ongoing research on the generation and transmission of intense microwave pulses. Significant progress was reported on high-power, high-current relativistic klystron amplifier research and design. Other work presented at the conference, include research on a high-power relativistic magnetron driven by a high-current linear induction accelerator, derivation of a Pierce-type dispersion relation describing the interaction of an intense relativistic electron beam with a corrugated cylindrical slow-wave structure, experiments on an X-band backward-wave cyclotron maser oscillator, and observation of frequency chirping in a free electron laser amplifier. Other presentations included work on multiwave Cerenkov generator experiments, analysis of resonance characteristics of slow-wave structures in high-power Cerenkov devices, linear analysis and numerical simulation of Doppler-shifted cyclotron harmonics in a cyclotron autoresonance klystron, high-power virtual cathode oscillator theory and experiments, design of a sixth-harmonic gyrofrequency multiplier as a millimeter-wave source, and experiments on dielectric-loaded and multiwave slotted gyro-TWT amplifiers. A review was presented on innovative concepts which employ high-power microwaves in propulsion of space vehicles. Separate abstracts were prepared for 34 papers of this conference

Hydrocarbons in interstellar ice analogues : UV-vis spectroscopy and VUV photochemistry

NARCIS (Netherlands)

Cuylle, Steven Hendrik

2015-01-01

This thesis treats the chemical behaviour of carbonaceous molecules in water-dominated interstellar ices. VUV photons are considered as the chemical trigger to induce solid state chemistry as it is omnipresent. Lyman- radiation occurs even in dense molecular clouds as a result of cosmic ray

Ion acceleration with ultra intense and ultra short laser pulses

International Nuclear Information System (INIS)

Floquet, V.

2012-01-01

Accelerating ions/protons can be done using short laser pulse (few femto-seconds) focused on few micrometers area on solid target (carbon, aluminum, plastic...). The electromagnetic field intensity reached on target (≥10 18 W.cm -2 ) allows us to turn the solid into a hot dense plasma. The dynamic motion of the electrons is responsible for the creation of intense static electric field at the plasma boundaries. These electric fields accelerate organic pollutants (including protons) located at the boundaries. This acceleration mechanism known as the Target Normal Sheath Acceleration (TNSA) has been the topic of the research presented in this thesis.The goal of this work has been to study the acceleration mechanism and to increase the maximal ion energy achievable. Indeed, societal application such as proton therapy requires proton energy up to few hundreds of MeV. To proceed, we have studied different target configurations allowing us to increase the laser plasma coupling and to transfer as much energy as possible to ions (target with microspheres deposit, foam target, grating). Different experiments have also dealt with generating a pre-plasma on the target surface thanks to a pre-pulse. On the application side, fluorescent material such as CdWO 4 has been studied under high flux rate of protons. These high flux rates have been, up to now, beyond the conventional accelerators capabilities. (author) [fr

EVALUATION OF THE THERAPEUTIC EFFICACY OF HIGH-INTENSITY PULSED-PERIODIC LASER RADIATION (CLINICAL AND EXPERIMENTAL OBSERVATIONS

Directory of Open Access Journals (Sweden)

V. V. Sokolov

2016-01-01

Full Text Available From the experience of clinical observations, we have shown a high therapeutic effectiveness of the medical laser KULON-MED in: cosmetics, non-cancer inflammatory diseases of the gastrointestinal tract and cancer (cancer of the stomach and colon as at different wavelengths, and with different types of photosensitizers. In the area of anti-tumor photodynamic therapy (PDT, based on experimental studies, we have showed the high antitumor (sarcoma S‑37 effectiveness of the laser (with the inhibition of tumor growth of up to 100% for repetitively pulsed irradiation mode, and for mode fractionation doses laser radiation. In addition, significant differences are shown in the effectiveness of anticancer PDT methods in the application of high-intensity lasers, continuous and pulsed caused fundamental properties of laser radiation characteristics – time structure of the radiation pulses. Thus, for the first time we have shown that the time of high-intensity laser pulses structure significantly affects therapeutic efficacy laser system, and hence on the mechanisms of interaction of laser radiation with biological tissue.

Adiabatic theory of ionization of atoms by intense laser pulses

International Nuclear Information System (INIS)

Tolstikhin, Oleg I; Morishita, Toru; Watanabe, Shinichi

2009-01-01

As a first step towards the adiabatic theory of ionization of atoms by intense laser pulses, here we consider the simplest one-dimensional zero-range potential model. The asymptotic solution to the time-dependent Schroedinger equation in the adiabatic regime is obtained and the photoelectron spectrum is calculated. The factorization formula for the photoelectron spectrum in the back-rescattering region, first suggested by Morishita et al. [Phys. Rev. Lett. 100, 013903 (2008)] on the basis of ab initio calculations, is derived analytically.

Krypton excimer laser oscillation by discharge pumping

International Nuclear Information System (INIS)

Shirai, Takahiro; Tabe, Yoshitaka; Kubodera, Shoichi; Sasaki, Wataru; Kawanaka, Junji

2001-01-01

We have demonstrated vacuum ultraviolet (VUV) laser oscillation of the krypton excimer (Kr 2 *) excited by a compact self-sustained discharge device. We have observed a spectral narrowing of the Kr 2 * emission centered at 147.8 nm. A deconvoluted spectral width is 0.5 nm (FWHM), which reveals a contrast to a 13 nm spectral width of the spontaneous emission. The Kr 2 * intensity has increased one order of magnitude when a charging voltage was increased larger than 29 kV. The success of the lasing in the VUV spectral region has been attributed to the success of a stable glow discharge of Kr at 10 atm. The pulse width of the VUV laser radiation is 400 ns (FWHM). The maximum output energy measured is as large as 150 μJ. (author)

Particle-in-cell simulations of high energy electron production by intense laser pulses in underdense plasmas

International Nuclear Information System (INIS)

Susumu, Kato; Eisuke, Miura; Kazuyoshi, Koyama; Mitsumori, Tanimoto; Masahiro, Adachi

2004-01-01

The propagation of intense laser pulses and the generation of high energy electrons from underdense plasmas are investigated using two dimensional particle-in-cell simulations. When the ratio of the laser power to the critical power of relativistic self-focusing gets the optimal value, the laser pulse propagates in a steady way and electrons have maximum energies. (author)

Particle-in-cell simulations of high energy electron production by intense laser pulses in underdense plasmas

Energy Technology Data Exchange (ETDEWEB)

Susumu, Kato; Eisuke, Miura; Kazuyoshi, Koyama [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki (Japan); Mitsumori, Tanimoto [Meisei Univ., Dept. of Electrical Engineering, Hino, Tokyo (Japan); Masahiro, Adachi [Hiroshima Univ., Graduate school of Advanced Science of Matter, Higashi-Hiroshima, Hiroshima (Japan)

2004-07-01

The propagation of intense laser pulses and the generation of high energy electrons from underdense plasmas are investigated using two dimensional particle-in-cell simulations. When the ratio of the laser power to the critical power of relativistic self-focusing gets the optimal value, the laser pulse propagates in a steady way and electrons have maximum energies. (author)

Techniques for Pump-Probe Synchronisation of Fsec Radiation Pulses

CERN Document Server

Schlarb, Holger

2005-01-01

The increasing interest on the production of ultra-short photon pulses in future generations of Free-Electron Lasers operating in the UV, VUV or X-ray regime demands new techniques to reliably measure and control the arrival time of the FEL-pulses at the experiment. For pump-probe experiments using external optical lasers the desired synchronisation is in the order of tens of femtoseconds, the typical duration of the FEL pulse. Since, the accelerators are large scale facilities of the length of several hundred meters or even kilometers, the problem of synchronisation has to be attacked twofold. First, the RF acceleration sections upstream of the magnetic bunch compressors need to be stabilised in amplitude and phase to high precision. Second, the remain electron beam timing jitter needs to be determined with femtosecond accuracy for off-line analysis. In this talk, several techniques using the electron or the FEL beam to monitor the arrival time are presented, and the proposed layout of the synchronisation sy...

Angle-resolved photoemission spectroscopy with 9-eV photon-energy pulses generated in a gas-filled hollow-core photonic crystal fiber

OpenAIRE

Bromberger, H.; Ermolov, A.; Belli, F.; Liu, H.; Calegari, F.; Chavez-Cervantes, M.; Li, M. T.; Lin, C. T.; Abdolvand, A.; Russell, P. St. J.; Cavalleri, A.; Travers, J. C.; Gierz, I.

2015-01-01

A recently developed source of ultraviolet radiation, based on optical soliton propagation in a gas-filled hollow-core photonic crystal fiber, is applied here to angle-resolved photoemission spectroscopy (ARPES). Near-infrared femtosecond pulses of only few {\\mu}J energy generate vacuum ultraviolet (VUV) radiation between 5.5 and 9 eV inside the gas-filled fiber. These pulses are used to measure the band structure of the topological insulator Bi2Se3 with a signal to noise ratio comparable to ...

Modeling high-intensity pulsed electric field inactivation of a lipase from Pseudomonas fluorescens.

Science.gov (United States)

Soliva-Fortuny, R; Bendicho-Porta, S; Martín-Belloso, O

2006-11-01

The inactivation kinetics of a lipase from Pseudomonas fluorescens (EC 3.1.1.3.) were studied in a simulated skim milk ultrafiltrate treated with high-intensity pulsed electric fields. Samples were subjected to electric field intensities ranging from 16.4 to 27.4 kV/cm for up to 314.5 micros, thus achieving a maximum inactivation of 62.1%. The suitability of describing experimental data using mechanistic first-order kinetics and an empirical model based on the Weibull distribution function is discussed. In addition, different mathematical expressions relating the residual activity values to field strength and treatment time are supplied. A first-order fractional conversion model predicted residual activity with good accuracy (A(f) = 1.018). A mechanistic insight of the model kinetics was that experimental values were the consequence of different structural organizations of the enzyme, with uneven resistance to the pulsed electric field treatments. The Weibull model was also useful in predicting the energy density necessary to achieve lipase inactivation.

Feasibility analysis for attosecond X-ray pulses at FERMI@ELETTRA free electron laser

Energy Technology Data Exchange (ETDEWEB)

Zholents, Alexander

2004-09-01

We present preliminary analysis for the feasibility of the attosecond x-ray pulses at a proposed FERMI@ELETTRA free electron laser (FEL) [1]. In part 1 we restrict ourselves to minimal modifications to the proposed FEL and consider a scheme for attosecond x-ray production which can be qualified as a small add-on to a primary facility. We demonstrate that at 5-nm wavelength our scheme is capable for production of pulses with an approximate duration of 100 attoseconds at approximately 2 MW peak power and with an absolute temporal synchronization to a pump laser pulse. In part 2 we propose to use an FEL amplifier seeded by a VUV signal and to follow it by the scheme for attosecond x-ray production described in part 1.

VUV photo-oxidation of gaseous benzene combined with ozone-assisted catalytic oxidation: Effect on transition metal catalyst

International Nuclear Information System (INIS)

Huang, Haibao; Lu, Haoxian; Zhan, Yujie; Liu, Gaoyuan; Feng, Qiuyu; Huang, Huiling; Wu, Muyan; Ye, Xinguo

2017-01-01

Graphical abstract: Mn nanoparticles are highly dispersed on ZSM-5 and most efficient in benzene degradation in the VUV-OZCO process. - Highlights: • Vacuum UV irradiation is well combined with O_3 catalytic oxidation. • O_3 byproducts was used to enhance catalytic oxidation of VOCs. • Mn/ZSM-5 achieved the best catalytic activity for benzene degradation. - Abstract: Volatile organic compounds (VOCs) cause the major air pollution concern. In this study, a series of ZSM-5 supported transition metals were prepared by impregnation method. They were combined with vacuum UV (VUV) photo-oxidation in a continuous-flow packed-bed reactor and used for the degradation of benzene, a typical toxic VOCs. Compared with VUV photo-oxidation alone, the introduction of catalysts can greatly enhance benzene oxidation under the help of O_3, the by-products from VUV irradiation, via ozone-assisted catalytic oxidation (OZCO). The catalytic activity of transition metals towards benzene oxidation followed the order: Mn > Co > Cu > Ni > Fe. Mn achieved the best catalytic activity due to the strongest capability for O_3 catalytic decomposition and utilization. Benzene and O_3 removal efficiency reached as high as 97% and 100% after 360 min, respectively. O_3 was catalytically decomposed, generating highly reactive oxidants such as ·OH and ·O for benzene oxidation.

VUV photo-oxidation of gaseous benzene combined with ozone-assisted catalytic oxidation: Effect on transition metal catalyst

Energy Technology Data Exchange (ETDEWEB)

Huang, Haibao, E-mail: seabao8@gmail.com [School of Environmental Science and Engineering, Sun Yat-Sen University (China); Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology (Sun Yat-sen University) (China); Lu, Haoxian; Zhan, Yujie; Liu, Gaoyuan; Feng, Qiuyu; Huang, Huiling; Wu, Muyan; Ye, Xinguo [School of Environmental Science and Engineering, Sun Yat-Sen University (China)

2017-01-01

Graphical abstract: Mn nanoparticles are highly dispersed on ZSM-5 and most efficient in benzene degradation in the VUV-OZCO process. - Highlights: • Vacuum UV irradiation is well combined with O{sub 3} catalytic oxidation. • O{sub 3} byproducts was used to enhance catalytic oxidation of VOCs. • Mn/ZSM-5 achieved the best catalytic activity for benzene degradation. - Abstract: Volatile organic compounds (VOCs) cause the major air pollution concern. In this study, a series of ZSM-5 supported transition metals were prepared by impregnation method. They were combined with vacuum UV (VUV) photo-oxidation in a continuous-flow packed-bed reactor and used for the degradation of benzene, a typical toxic VOCs. Compared with VUV photo-oxidation alone, the introduction of catalysts can greatly enhance benzene oxidation under the help of O{sub 3}, the by-products from VUV irradiation, via ozone-assisted catalytic oxidation (OZCO). The catalytic activity of transition metals towards benzene oxidation followed the order: Mn > Co > Cu > Ni > Fe. Mn achieved the best catalytic activity due to the strongest capability for O{sub 3} catalytic decomposition and utilization. Benzene and O{sub 3} removal efficiency reached as high as 97% and 100% after 360 min, respectively. O{sub 3} was catalytically decomposed, generating highly reactive oxidants such as ·OH and ·O for benzene oxidation.

Interrogation of orbital structure by elliptically polarized intense femtosecond laser pulses

International Nuclear Information System (INIS)

Abu-samha, M.; Madsen, L. B.

2011-01-01

We solve the three-dimensional time-dependent Schroedinger equation and present investigations of the imprint of the orbital angular node in photoelectron momentum distributions of an aligned atomic p-type orbital following ionization by an intense elliptically polarized laser pulse of femtosecond duration. We investigate the role of light ellipticity and the alignment angle of the major polarization axis of the external field relative to the probed orbital by studying radial and angular momentum distributions, the latter at a fixed narrow interval of final momenta close to the peak of the photoelectron momentum distribution. In general only the angular distributions carry a clear signature of the orbital symmetry. Our study shows that circular polarization gives the most clear imprints of orbital nodes. These findings are insensitive to pulse duration.

VUV Pump and Probe of Phase Separation and Oxygen Interstitials in La2NiO4+y Using Spectromicroscopy

Directory of Open Access Journals (Sweden)

Antonio Bianconi

2018-02-01

Full Text Available While it is known that strongly correlated transition metal oxides described by a multi-band Hubbard model show microscopic multiscale phase separation, little is known about the possibility to manipulate them with vacuum ultraviolet (VUV, 27 eV lighting. We have investigated the photo-induced effects of VUV light illumination of a super-oxygenated La2NiO4+y single crystal by means of scanning photoelectron microscopy. VUV light exposure induces the increase of the density of states (DOS in the binding energy range around Eb = 1.4 eV below EF. The photo-induced states in this energy region have been predicted due to clustering of oxygen interstitials by band structure calculations for large supercell of La2CuO4.125. We finally show that it is possible to generate and manipulate oxygen rich domains by VUV illumination as it was reported for X-ray illumination of La2CuO4+y. This phenomenology is assigned to oxygen-interstitials ordering and clustering by photo-illumination forming segregated domains in the La2NiO4+y surface.

Time-resolved measurements with intense ultrashort laser pulses: a 'molecular movie' in real time

International Nuclear Information System (INIS)

Rudenko, A; Ergler, Th; Feuerstein, B; Zrost, K; Schroeter, C D; Moshammer, R; Ullrich, J

2007-01-01

We report on the high-resolution multidimensional real-time mapping of H 2 + and D 2 + nuclear wave packets performed employing time-resolved three-dimensional Coulomb explosion imaging with intense laser pulses. Exploiting a combination of a 'reaction microscope' spectrometer and a pump-probe setup with two intense 6-7 fs laser pulses, we simultaneously visualize both vibrational and rotational motion of the molecule, and obtain a sequence of snapshots of the squared ro-vibrational wave function with time-step resolution of ∼ 0.3 fs, allowing us to reconstruct a real-time movie of the ultrafast molecular motion. We observe fast dephasing, or 'collapse' of the vibrational wave packet and its subsequent revival, as well as signatures of rotational excitation. For D 2 + we resolve also the fractional revivals resulting from the interference between the counter-propagating parts of the wave packet

In vivo hyperthermia effect induced by high-intensity pulsed ultrasound

International Nuclear Information System (INIS)

Cui Wei-Cheng; Tu Juan; Li Qian; Fan Ting-Bo; Zhang Dong; Chen Wei-Zhong; Joo-Ha Hwang; Chen Jing-Hai

2012-01-01

Hyperthermia effects (39–44 °C) induced by pulsed high-intensity focused ultrasound (HIFU) have been regarded as a promising therapeutic tool for boosting immune responses or enhancing drug delivery into a solid tumor. However, previous studies also reported that the cell death occurs when cells are maintained at 43 °C for more than 20 minutes. The aim of this study is to investigate thermal responses inside in vivo rabbit auricular veins exposed to pulsed HIFU (1.17 MHz, 5300 W/cm 2 , with relatively low-duty ratios (0.2%–4.3%). The results show that: (1) with constant pulse repetition frequency (PRF) (e.g., 1 Hz), the thermal responses inside the vessel will increase with the increasing duty ratio; (2) a temperature elevation to 43 °C can be identified at the duty ratio of 4.3%; (3) with constant duty ratios, the change of PRF will not significantly affect the temperature measurement in the vessel; (4) as the duty ratios lower than 4.3%, the presence of microbubbles will not significantly enhance the thermal responses in the vessel, but will facilitate HIFU-induced inertial cavitation events. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Unconventional use of intense pulsed light.

Science.gov (United States)

Piccolo, D; Di Marcantonio, D; Crisman, G; Cannarozzo, G; Sannino, M; Chiricozzi, A; Chimenti, S

2014-01-01

According to the literature, intense pulsed light (IPL) represents a versatile tool in the treatment of some dermatological conditions (i.e., pigmentation disorders, hair removal, and acne), due to its wide range of wavelengths. The authors herein report on 58 unconventional but effective uses of IPL in several cutaneous diseases, such as rosacea (10 cases), port-wine stain (PWS) (10 cases), disseminated porokeratosis (10 cases), pilonidal cyst (3 cases), seborrheic keratosis (10 cases), hypertrophic scar (5 cases) and keloid scar (5 cases), Becker's nevus (2 cases), hidradenitis suppurativa (2 cases), and sarcoidosis (1 case). Our results should suggest that IPL could represent a valid therapeutic support and option by providing excellent outcomes and low side effects, even though it should be underlined that the use and the effectiveness of IPL are strongly related to the operator's experience (acquired by attempting at least one specific course on the use of IPL and one-year experience in a specialized centre). Moreover, the daily use of these devices will surely increase clinical experience and provide new information, thus enhancing long-term results and improving IPL effectiveness.

Ionization of molecular hydrogen in ultrashort intense laser pulses

Energy Technology Data Exchange (ETDEWEB)

Vanne, Yulian V.

2010-03-18

A novel ab initio numerical approach is developed and applied that solves the time-dependent Schroedinger equation describing two-electron diatomic molecules (e.g. molecular hydrogen) exposed to an intense ultrashort laser pulse. The method is based on the fixed-nuclei and the non-relativistic dipole approximations and aims to accurately describe both correlated electrons in full dimensionality. The method is applicable for a wide range of the laser pulse parameters and is able to describe both few-photon and many-photon single ionization processes, also in a non-perturbative regime. A key advantage of the method is its ability to treat the strong-field response of the molecules with arbitrary orientation of the molecular axis with respect to the linear-polarized laser field. Thus, this work reports on the first successful orientation-dependent analysis of the multiphoton ionization of H{sub 2} performed by means of a full-dimensional numerical treatment. Besides the investigation of few-photon regime, an extensive numerical study of the ionization by ultrashort frequency-doubled Ti:sapphire laser pulses (400 nm) is presented. Performing a series of calculations for different internuclear separations, the total ionization yields of H{sub 2} and D{sub 2} in their ground vibrational states are obtained for both parallel and perpendicular orientations. A series of calculations for 800 nm laser pulses are used to test a popular simple interference model. Besides the discussion of the ab initio numerical method, this work considers different aspects related to the application of the strong-field approximation (SFA) for investigation of a strong-field response of an atomic and molecular system. Thus, a deep analysis of the gauge problem of SFA is performed and the quasistatic limit of the velocity-gauge SFA ionization rates is derived. The applications of the length-gauge SFA are examined and a recently proposed generalized Keldysh theory is criticized. (orig.)

Ionization of molecular hydrogen in ultrashort intense laser pulses

International Nuclear Information System (INIS)

Vanne, Yulian V.

2010-01-01

A novel ab initio numerical approach is developed and applied that solves the time-dependent Schroedinger equation describing two-electron diatomic molecules (e.g. molecular hydrogen) exposed to an intense ultrashort laser pulse. The method is based on the fixed-nuclei and the non-relativistic dipole approximations and aims to accurately describe both correlated electrons in full dimensionality. The method is applicable for a wide range of the laser pulse parameters and is able to describe both few-photon and many-photon single ionization processes, also in a non-perturbative regime. A key advantage of the method is its ability to treat the strong-field response of the molecules with arbitrary orientation of the molecular axis with respect to the linear-polarized laser field. Thus, this work reports on the first successful orientation-dependent analysis of the multiphoton ionization of H 2 performed by means of a full-dimensional numerical treatment. Besides the investigation of few-photon regime, an extensive numerical study of the ionization by ultrashort frequency-doubled Ti:sapphire laser pulses (400 nm) is presented. Performing a series of calculations for different internuclear separations, the total ionization yields of H 2 and D 2 in their ground vibrational states are obtained for both parallel and perpendicular orientations. A series of calculations for 800 nm laser pulses are used to test a popular simple interference model. Besides the discussion of the ab initio numerical method, this work considers different aspects related to the application of the strong-field approximation (SFA) for investigation of a strong-field response of an atomic and molecular system. Thus, a deep analysis of the gauge problem of SFA is performed and the quasistatic limit of the velocity-gauge SFA ionization rates is derived. The applications of the length-gauge SFA are examined and a recently proposed generalized Keldysh theory is criticized. (orig.)

A VUV photoionization organic aerosol mass spectrometric study with synchrotron radiation

Energy Technology Data Exchange (ETDEWEB)

Fang Wenzheng; Lei Gong; Shan Xiaobin; Liu Fuyi [School of Nuclear Science and Technology, National Synchrotron Radiation Laboratory, University of Science and Technology of China, Anhui, Hefei 230029 (China); Wang Zhenya [Laboratory of Environmental Spectroscopy, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031 (China); Sheng Liusi, E-mail: lssheng@ustc.edu.cn [School of Nuclear Science and Technology, National Synchrotron Radiation Laboratory, University of Science and Technology of China, Anhui, Hefei 230029 (China)

2011-04-15

Research highlights: {yields} A photoionization aerosol time-of-flight mass spectrometer (ATOFMS) has been developed for on-line analysis of organic compounds in aerosol particles using tunable vacuum ultraviolet (VUV) synchrotron radiation. {yields} The degree of fragmentation of molecule can be controlled either by the heater temperature or by the photon energy. {yields} The direct determination of the IEs of benzopheneone (9.07 eV), salicylic acid (8.72 eV), and urea (9.85 eV) are measured from the photoionization efficiency spectra. {yields} The species can be identified by their molecular and fragment ions weights as well as by the comparisions between their theoretical and experimental ionization energies. - Abstract: A photoionization aerosol time-of-flight mass spectrometer (ATOFMS) has been developed for on-line analysis of organic compounds in aerosol particles using tunable vacuum ultraviolet (VUV) synchrotron radiation. Aerosol particles can be sampled directly from atmospheric pressure and are focused through an aerodynamic lens assembly into the mass spectrometer. The particles are vaporized when they impact on a heater, and then the nascent vapor is softly photoionized by synchrotron radiation. The degree of fragmentation of molecule can be controlled either by the heater temperature or by the photon energy. Thus, fragment-free tunable VUV mass spectra are obtained by tuning the photon energy close to the ionization energies (IEs) of the sample molecules. The direct determination of the IEs of benzophenone (9.07 eV), salicylic acid (8.72 eV), and urea (9.85 eV) are measured from the photoionization efficiency spectra with uncertainties of {+-}50 meV. Ab initio calculations have been employed to predict the theoretical ionization energy.

Nanostructured surface processing by an intense pulsed ion beam irradiation

International Nuclear Information System (INIS)

Yatsuzuka, M.; Masuda, T.; Yamasaki, T.; Uchida, H.; Nobuhara, S.; Hashimoto, Y.; Yoshihara, Y.

1997-01-01

Metal surface modification by irradiating an intense pulsed ion beam (IPIB) with short pulse width has been studied experimentally. An IPIB irradiation to a target leads to rapid heating above its melting point. After the beam is turned off, the heated region is immediately cooled by thermal conduction at a cooling rate of typically 10 10 K/s. This rapid cooling and resolidification results in generation of nanostructured phase in the top of surface. The typical hydrogen IPIB parameters are 200 kV of energy, 500 A/cm 2 of current density and 70 ns of pulsewidth. The IPIB was irradiated on a pure titanium to generate nanocrystalline phase. The IPIB-irradiated surface was examined with X-ray diffraction, SEM, and HR-TEM. The randomly oriented lattice fringes as well as a halo diffraction pattern are observed in the HR-TEM micrograph of IPIB-irradiated titanium. The average grain size is found to be 32 nanometers

VUV photo-oxidation of gaseous benzene combined with ozone-assisted catalytic oxidation: Effect on transition metal catalyst

Science.gov (United States)

Huang, Haibao; Lu, Haoxian; Zhan, Yujie; Liu, Gaoyuan; Feng, Qiuyu; Huang, Huiling; Wu, Muyan; Ye, Xinguo

2017-01-01

Volatile organic compounds (VOCs) cause the major air pollution concern. In this study, a series of ZSM-5 supported transition metals were prepared by impregnation method. They were combined with vacuum UV (VUV) photo-oxidation in a continuous-flow packed-bed reactor and used for the degradation of benzene, a typical toxic VOCs. Compared with VUV photo-oxidation alone, the introduction of catalysts can greatly enhance benzene oxidation under the help of O3, the by-products from VUV irradiation, via ozone-assisted catalytic oxidation (OZCO). The catalytic activity of transition metals towards benzene oxidation followed the order: Mn > Co > Cu > Ni > Fe. Mn achieved the best catalytic activity due to the strongest capability for O3 catalytic decomposition and utilization. Benzene and O3 removal efficiency reached as high as 97% and 100% after 360 min, respectively. O3 was catalytically decomposed, generating highly reactive oxidants such as rad OH and rad O for benzene oxidation.

Atomic and Molecular Systems in Intense Ultrashort Laser Pulses

Science.gov (United States)

Saenz, A.

2008-07-01

The full quantum mechanical treatment of atomic and molecular systems exposed to intense laser pulses is a so far unsolved challenge, even for systems as small as molecular hydrogen. Therefore, a number of simplified qualitative and quantitative models have been introduced in order to provide at least some interpretational tools for experimental data. The assessment of these models describing the molecular response is complicated, since a comparison to experiment requires often a number of averages to be performed. This includes in many cases averaging of different orientations of the molecule with respect to the laser field, focal volume effects, etc. Furthermore, the pulse shape and even the peak intensity is experimentally not known with very high precision; considering, e.g., the exponential intensity dependence of the ionization signal. Finally, experiments usually provide only relative yields. As a consequence of all these averagings and uncertainties, it is possible that different models may successfully explain some experimental results or features, although these models disagree substantially, if their predictions are compared before averaging. Therefore, fully quantum-mechanical approaches at least for small atomic and molecular systems are highly desirable and have been developed in our group. This includes efficient codes for solving the time-dependent Schrodinger equation of atomic hydrogen, helium or other effective one- or two-electron atoms as well as for the electronic motion in linear (effective) one-and two-electron diatomic molecules like H_2.Very recently, a code for larger molecular systems that adopts the so-called single-active electron approximation was also successfully implemented and applied. In the first part of this talk popular models describing intense laser-field ionization of atoms and their extensions to molecules are described. Then their validity is discussed on the basis of quantum-mechanical calculations. Finally, some

Impact of high-intensity pulsed electric fields on carotenoids profile of tomato juice made of moderate-intensity pulsed electric field-treated tomatoes.

Science.gov (United States)

Vallverdú-Queralt, Anna; Odriozola-Serrano, Isabel; Oms-Oliu, Gemma; Lamuela-Raventós, Rosa M; Elez-Martínez, Pedro; Martín-Belloso, Olga

2013-12-01

The effect of pulsed electric fields (PEF) on the carotenoid content of tomato juices was studied. First, moderate-intensity PEF (MIPEF) was applied to raw tomatoes. Afterwards, MIPEF-treated and untreated tomatoes were immediately refrigerated at 4 °C for 24 h and then, they were separately ground to produce tomato juices. Juices were treated by heat treatments or by high-intensity PEF (HIPEF) and stored under refrigeration for 56 days. MIPEF treatment of tomatoes increased the content of carotenoid compounds in tomato juices. An enhancement of 63-65% in 15-cis-lycopene was observed in juices prepared with MIPEF-treated tomatoes. A slight increase in cis-lycopene isomers was observed over time, whereas other carotenoids slightly decreased. However, HIPEF treated tomato juices maintained higher carotenoid content (10-20%) through the storage time than thermally and untreated juices. The combination of MIPEF and HIPEF treatments could be used not only to produce tomato juices with high carotenoid content but also, to maintain higher the carotenoid content during storage time. Copyright © 2013 Elsevier Ltd. All rights reserved.

Preliminary tests of a second harmonic rf system for the intense pulsed neutron source synchrotron

International Nuclear Information System (INIS)

Norem, J.; Brandeberry, F.

1983-01-01

The Rapid Cycling Synchrotron (RCS) of the Intense Pulsed Neutron Source (IPNS) operating at Argonne National Laboratory is presently producing intensities of 2 to 2.5 x 10 12 protons per pulse (ppp) with the addition of a new ion source. This intensity is close to the space charge limit of the machine, estimated at approx. 3 x 10 12 ppp, depending somewhat on the available aperture. Accelerator improvements are being directed at (1) increasing beam intensities for neutron science, (2) lowering acceleration losses to minimize activation, and (3) gaining better control of the beam so that losses can be made to occur when and where they can be most easily controlled. We are now proposing a third cavity for the RF system which would provide control of the longitudinal bunch shape during the cycle which would permit raising the effective space charge limit of the accelerator and reducing losses by providing more RF voltage at maximum acceleration. This paper presents an outline of the expected benefits together with recent results obtained during low energy operation with one of the two existing cavities operating at the second harmonic

Future prospects for studies in the VUV-SX region

International Nuclear Information System (INIS)

Tanaka, Kenichiro; Kitajima, Yoshinori

1989-09-01

This book carries papers presented at a workshop 'Future Prospects for Studies in the VUV-SX Region' held on March 22 and 23, 1989. The workshop focussed particularly on the promotion of research in the VUV and soft X-ray regions. Three sessions were held: Session 1 for studies in peripheral areas, Session 2 for theoretical studies, and Session 3 for recent developments. Session 1 covered five studies: 'Laser Spectroscopy: High-Resolution Observation of Highly Electronically Excited Gaseous Molecule', 'High-Resolution Electron Spectroscopy: Surface Phonon Spectroscopy', 'Experimental Study on Atoms and Molecules through Ion Trap', 'Basic Mechanism of Photo-Induced CVD', and 'Application of Circularly Polarized Light'. Session 2 covered five studies: 'Electronic State of High Tc Superconducting Oxide', 'Surface Condition and Electronic State', 'XES and XAS Study of Rare Earth Compound', 'Resonance Photoelectric Spectroscopy on Strongly Correlated Electronic System', and 'Circularly Polarized Light and Atomic Process in Soft X-Ray Region'. Session 3 covered six studies: 'Prospects of Application of Supercritical Liquid to Research on Physical Characteristics', 'Application of Orbit Radiation to Polarization Spectroscopy', 'XES Research for La Compounds', 'Characteristics of Ultra-Fine Particles', 'Surface Study by Angular-Resolution Photoelectric Spectroscopy', and 'EXAFS Study of Light Element'. (N.K.)

The fluid dynamics of microjet explosions caused by extremely intense X-ray pulses

Science.gov (United States)

Stan, Claudiu; Laksmono, Hartawan; Sierra, Raymond; Milathianaki, Despina; Koglin, Jason; Messerschmidt, Marc; Williams, Garth; Demirci, Hasan; Botha, Sabine; Nass, Karol; Stone, Howard; Schlichting, Ilme; Shoeman, Robert; Boutet, Sebastien

2014-11-01

Femtosecond X-ray scattering experiments at free-electron laser facilities typically requires liquid jet delivery methods to bring samples to the region of interaction with X-rays. We have imaged optically the damage process in water microjets due to intense hard X-ray pulses at the Linac Coherent Light Source (LCLS), using time-resolved imaging techniques to record movies at rates up to half a billion frames per second. For pulse energies larger than a few percent of the maximum pulse energy available at LCLS, the X-rays deposit energies much larger than the latent heat of vaporization in water, and induce a phase explosion that opens a gap in the jet. The LCLS pulses last a few tens of femtoseconds, but the full evolution of the broken jet is orders of magnitude slower - typically in the microsecond range - due to complex fluid dynamics processes triggered by the phase explosion. Although the explosion results in a complex sequence of phenomena, they lead to an approximately self-similar flow of the liquid in the jet.

High Intensity Femtosecond XUV Pulse Interactions with Atomic Clusters: Final Report

Energy Technology Data Exchange (ETDEWEB)

Ditmire, Todd [Univ. of Texas, Austin, TX (United States). Center for High Energy Density Science

2016-10-12

We propose to expand our recent studies on the interactions of intense extreme ultraviolet (XUV) femtosecond pulses with atomic and molecular clusters. The work described follows directly from work performed under BES support for the past grant period. During this period we upgraded the THOR laser at UT Austin by replacing the regenerative amplifier with optical parametric amplification (OPA) using BBO crystals. This increased the contrast of the laser, the total laser energy to ~1.2 J , and decreased the pulse width to below 30 fs. We built a new all reflective XUV harmonic beam line into expanded lab space. This enabled an increase influence by a factor of 25 and an increase in the intensity by a factor of 50. The goal of the program proposed in this renewal is to extend this class of experiments to available higher XUV intensity and a greater range of wavelengths. In particular we plan to perform experiments to confirm our hypothesis about the origin of the high charge states in these exploding clusters, an effect which we ascribe to plasma continuum lowering (ionization potential depression) in a cluster nano-­plasma. To do this we will perform experiments in which XUV pulses of carefully chosen wavelength irradiate clusters composed of only low-Z atoms and clusters with a mixture of this low-­Z atom with higher Z atoms. The latter clusters will exhibit higher electron densities and will serve to lower the ionization potential further than in the clusters composed only of low Z atoms. This should have a significant effect on the charge states produced in the exploding cluster. We will also explore the transition of explosions in these XUV irradiated clusters from hydrodynamic expansion to Coulomb explosion. The work proposed here will explore clusters of a wider range of constituents, including clusters from solids. Experiments on clusters from solids will be enabled by development we performed during the past grant period in which we constructed and

Beam line design for synchrotron spectroscopy in the VUV

Energy Technology Data Exchange (ETDEWEB)

Howells, M R

1980-01-01

The character of the radiation source provided by an electron storage ring is briefly reviewed from the point of view of utilization for VUV spectroscopy. The design of beam line components is then considered with special reference to the problems of contamination of optical surfaces and vacuum protection. The issues involved in designing mirrors for use with storage rings are considered with emphasis on the questions of power dissipation, image quality and materials selection.

Beam line design for synchrotron spectroscopy in the VUV

International Nuclear Information System (INIS)

Howells, M.R.

1980-01-01

The character of the radiation source provided by an electron storage ring is briefly reviewed from the point of view of utilization for VUV spectroscopy. The design of beam line components is then considered with special reference to the problems of contamination of optical surfaces and vacuum protection. The issues involved in designing mirrors for use with storage rings are considered with emphasis on the questions of power dissipation, image quality and materials selection

Designing Neutralized Drift Compression for Focusing of Intense Ion Beam Pulses in a Background Plasma

International Nuclear Information System (INIS)

Kaganovich, I.D.; Davidson, R.C.; Dorf, M.; Startsev, E.A.; Barnard, J.J.; Friedman, A.; Lee, E.P.; Lidia, S.M.; Logan, B.G.; Roy, P.K.; Seidl, P.A.; Welch, D.R.; Sefkow, A.B.

2009-01-01

Neutralized drift compression offers an effective method for particle beam focusing and current amplification. In neutralized drift compression, a linear radial and longitudinal velocity drift is applied to a beam pulse, so that the beam pulse compresses as it drifts in the drift-compression section. The beam intensity can increase more than a factor of 100 in both the radial and longitudinal directions, resulting in more than 10,000 times increase in the beam number density during this process. The self-electric and self-magnetic fields can prevent tight ballistic focusing and have to be neutralized by supplying neutralizing electrons. This paper presents a survey of the present theoretical understanding of the drift compression process and plasma neutralization of intense particle beams. The optimal configuration of focusing and neutralizing elements is discussed in this paper.

The effect of intense light pulses on the sensory quality and instrumental color of meat from different animal breeds

OpenAIRE

Tomašević I.

2015-01-01

Intense light pulses (ILP) are an emerging processing technology, which has a potential to decontaminate food products. The light generated by ILP lamps consists of a continuum broadband spectrum from deep UV to the infrared, especially rich in UV range below 400 nm, which is germicidal. Evaluation of the effect of intense light pulses (ILP) on sensory quality of meat, game and poultry was performed using two kinds of red meat (beef and pork), two kinds of ...

Luminescent properties of (Y,Gd)BO3:Bi3+,RE3+ (RE=Eu, Tb) phosphor under VUV/UV excitation

International Nuclear Information System (INIS)

Zeng Xiaoqing; Im, Seoung-Jae; Jang, Sang-Hun; Kim, Young-Mo; Park, Hyoung-Bin; Son, Seung-Hyun; Hatanaka, Hidekazu; Kim, Gi-Young; Kim, Seul-Gi

2006-01-01

Bi 3+ - and RE 3+ -co-doped (Y,Gd)BO 3 phosphors were prepared and their luminescent properties under vacuum ultraviolet (VUV)/UV excitation were investigated. Strong red emission for (Y,Gd)BO 3 :Bi 3+ ,Eu 3+ and strong green emission for (Y,Gd)BO 3 :Bi 3+ ,Tb 3+ are observed under VUV excitation from 147 to 200 nm with a much broader excitation region than that of single Eu 3+ -doped or Tb 3+ -doped (Y,Gd)BO 3 phosphor. Strong emissions are also observed under UV excitation around 265 nm where as nearly no luminescence is observed for single Eu 3+ -doped or Tb 3+ -doped (Y,Gd)BO 3 . The luminescence enhancement of Bi 3+ - and RE 3+ -co-doped (Y,Gd)BO 3 phosphors is due to energy transfer from Bi 3+ ion to Eu 3+ or Tb 3+ ion not only in the VUV region but also in the UV region. Besides, host sensitization competition between Bi 3+ and Eu 3+ or Tb 3+ is also observed. The investigated phosphors may be preferable for devices with a VUV light 147-200 nm as an excitation source such as PDP or mercury-free fluorescent lamp

Wavelength dependence of momentum-space images of low-energy electrons generated by short intense laser pulses at high intensities

International Nuclear Information System (INIS)

Maharjan, C M; Alnaser, A S; Litvinyuk, I; Ranitovic, P; Cocke, C L

2006-01-01

We have measured momentum-space images of low-energy electrons generated by the interaction of short intense laser pulses with argon atoms at high intensities. We have done this over a wavelength range from 400 to 800 nm. The spectra show considerable structure in both the energy and angular distributions of the electrons. Some, but not all, energy features can be identified as multi-photon resonances. The angular structure shows a regularity which transcends the resonant structure and may be due instead to diffraction. The complexity of the results defies easy model-dependent interpretations and invites full solutions to Schroedinger's equation for these systems

Analog measurement of delayed antiproton annihilation time spectra in a high intensity pulsed antiproton beam

International Nuclear Information System (INIS)

Niestroj, A.; Hayano, R.S.; Ishikawa, T.; Tamura, H.; Torii, H.A.; Morita, N.; Yamazaki, T.; Sugai, I.; Nakayoshi, K.; Horvath, D.; Eades, J.; Widmann, E.

1996-01-01

An analog detection system has been developed to measure delayed antiproton annihilation time spectra for laser resonance spectroscopy of metastable antiprotonic helium atoms using the high-intensity pulsed beam of antiprotons from LEAR at CERN. (orig.)

A paradoxical signal intensity increase in fatty livers using opposed-phase gradient echo imaging with fat-suppression pulses

International Nuclear Information System (INIS)

Mulkern, Robert V.; Voss, Stephan; Loeb Salsberg, Sandra; Krauel, Marta Ramon; Ludwig, David S.

2008-01-01

With the increase in obese and overweight children, nonalcoholic fatty liver disease has become more prevalent in the pediatric population. Appreciating subtleties of magnetic resonance (MR) signal intensity behavior from fatty livers under different imaging conditions thus becomes important to pediatric radiologists. We report an initially confusing signal behavior - increased signal from fatty livers when fat-suppression pulses are applied in an opposed-phase gradient echo imaging sequence - and seek to explain the physical mechanisms for this paradoxical signal intensity behavior. Abdominal MR imaging at 3 T with a 3-D volumetric interpolated breath-hold (VIBE) sequence in the opposed-phase condition (TR/TE 3.3/1.3 ms) was performed in five obese boys (14±2 years of age, body mass index >95th percentile for age and sex) with spectroscopically confirmed fatty livers. Two VIBE acquisitions were performed, one with and one without the use of chemical shift selective (CHESS) pulse fat suppression. The ratios of fat-suppressed over non-fat-suppressed signal intensities were assessed in regions-of-interest (ROIs) in five tissues: subcutaneous fat, liver, vertebral marrow, muscle and spleen. The boys had spectroscopically estimated hepatic fat levels between 17% and 48%. CHESS pulse fat suppression decreased subcutaneous fat signals dramatically, by more than 85% within regions of optimal fat suppression. Fatty liver signals, in contrast, were elevated by an average of 87% with CHESS pulse fat suppression. Vertebral marrow signal was also significantly elevated with CHESS pulse fat suppression, while spleen and muscle signals demonstrated only small signal increases on the order of 10%. We demonstrated that CHESS pulse fat suppression actually increases the signal intensity from fatty livers in opposed-phase gradient echo imaging conditions. The increase can be attributed to suppression of one partner of the opposed-phase pair that normally contributes to the

A paradoxical signal intensity increase in fatty livers using opposed-phase gradient echo imaging with fat-suppression pulses

Energy Technology Data Exchange (ETDEWEB)

Mulkern, Robert V.; Voss, Stephan [Harvard Medical School, Department of Radiology, Children' s Hospital Boston, Boston, MA (United States); Loeb Salsberg, Sandra; Krauel, Marta Ramon; Ludwig, David S. [Harvard Medical School, Department of Medicine, Children' s Hospital Boston, Boston, MA (United States)

2008-10-15

With the increase in obese and overweight children, nonalcoholic fatty liver disease has become more prevalent in the pediatric population. Appreciating subtleties of magnetic resonance (MR) signal intensity behavior from fatty livers under different imaging conditions thus becomes important to pediatric radiologists. We report an initially confusing signal behavior - increased signal from fatty livers when fat-suppression pulses are applied in an opposed-phase gradient echo imaging sequence - and seek to explain the physical mechanisms for this paradoxical signal intensity behavior. Abdominal MR imaging at 3 T with a 3-D volumetric interpolated breath-hold (VIBE) sequence in the opposed-phase condition (TR/TE 3.3/1.3 ms) was performed in five obese boys (14{+-}2 years of age, body mass index >95th percentile for age and sex) with spectroscopically confirmed fatty livers. Two VIBE acquisitions were performed, one with and one without the use of chemical shift selective (CHESS) pulse fat suppression. The ratios of fat-suppressed over non-fat-suppressed signal intensities were assessed in regions-of-interest (ROIs) in five tissues: subcutaneous fat, liver, vertebral marrow, muscle and spleen. The boys had spectroscopically estimated hepatic fat levels between 17% and 48%. CHESS pulse fat suppression decreased subcutaneous fat signals dramatically, by more than 85% within regions of optimal fat suppression. Fatty liver signals, in contrast, were elevated by an average of 87% with CHESS pulse fat suppression. Vertebral marrow signal was also significantly elevated with CHESS pulse fat suppression, while spleen and muscle signals demonstrated only small signal increases on the order of 10%. We demonstrated that CHESS pulse fat suppression actually increases the signal intensity from fatty livers in opposed-phase gradient echo imaging conditions. The increase can be attributed to suppression of one partner of the opposed-phase pair that normally contributes to the

Characteristics of a nanosecond-barrier-discharge-pumped multiwave UV – VUV lamp on a mixture of argon, krypton and vapours of freon

Energy Technology Data Exchange (ETDEWEB)

Shuaibov, A K; Minya, A I; Hrytsak, R V; Gomoki, Z T [Uzhgorod National University, Uzhgorod (Ukraine)

2015-02-28

We present the results of investigation of the characteristics of a nanosecond-barrier-discharge-pumped multiwave lamp based on a gas mixture of Ar – Kr – CCl{sub 4}, which emits in the spectral range of 170 – 260 nm. The main emission bands in the lamp spectrum are ArCl (B → X) near 175 nm, KrCl (B → X) near 222 nm and Cl{sub 2} (D' → A') near 258 nm. The lamp intensity with respect to pressure, working mixture composition and pump regime is optimised. (uv - vuv emitters)

Unconventional Use of Intense Pulsed Light

Directory of Open Access Journals (Sweden)

D. Piccolo

2014-01-01

Full Text Available According to the literature, intense pulsed light (IPL represents a versatile tool in the treatment of some dermatological conditions (i.e., pigmentation disorders, hair removal, and acne, due to its wide range of wavelengths. The authors herein report on 58 unconventional but effective uses of IPL in several cutaneous diseases, such as rosacea (10 cases, port-wine stain (PWS (10 cases, disseminated porokeratosis (10 cases, pilonidal cyst (3 cases, seborrheic keratosis (10 cases, hypertrophic scar (5 cases and keloid scar (5 cases, Becker’s nevus (2 cases, hidradenitis suppurativa (2 cases, and sarcoidosis (1 case. Our results should suggest that IPL could represent a valid therapeutic support and option by providing excellent outcomes and low side effects, even though it should be underlined that the use and the effectiveness of IPL are strongly related to the operator’s experience (acquired by attempting at least one specific course on the use of IPL and one-year experience in a specialized centre. Moreover, the daily use of these devices will surely increase clinical experience and provide new information, thus enhancing long-term results and improving IPL effectiveness.

Intense, pulsed, charged particle beams and associated applications to materials science

Energy Technology Data Exchange (ETDEWEB)

Yatsui, K; Grigoriu, C; Masugata, K; Jiang, W; Sonegawa, T; Nakagawa, Y; Eka Prijono, A C [Nagaoka Univ. of Technology, Niigata (Japan)

1997-03-01

We have demonstrated successful preparation of thin films and nanosize powders by using the technique of intense pulsed ion beam evaporation. In this paper, we review the experimental results of thin film deposition of ZnS, YBa{sub 2}Cu{sub 3}O{sub 7-x}, BaTiO{sub 3}, cBN, ZrO{sub 2}, ITO, and apatite, as well as the experimental results of the synthesis of nanosize powders of Al{sub 2}O{sub 3}. (author)

Time-resolved VUV spectroscopy in the EXTRAP-T2 reversed field pinch

International Nuclear Information System (INIS)

Hedqvist, A.; Rachlew-Kaellne, E.

1998-01-01

Time-resolved VUV spectroscopy has been used to investigate the effects of impurities in a reversed field pinch operating with a resistive shell. Results of electron temperature, impurity ion densities, particle confinement time and Z eff together with a description of the interpretation and the equipment are presented. (author)

Nonlinear Dichroism in Back-to-Back Double Ionization of He by an Intense Elliptically Polarized Few-Cycle Extreme Ultraviolet Pulse.

Science.gov (United States)

Ngoko Djiokap, J M; Manakov, N L; Meremianin, A V; Hu, S X; Madsen, L B; Starace, Anthony F

2014-11-28

Control of double ionization of He by means of the polarization and carrier-envelope phase (CEP) of an intense, few-cycle extreme ultraviolet (XUV) pulse is demonstrated numerically by solving the six-dimensional two-electron, time-dependent Schrödinger equation for He interacting with an elliptically polarized XUV pulse. Guided by perturbation theory (PT), we predict the existence of a nonlinear dichroic effect (∝I^{3/2}) that is sensitive to the CEP, ellipticity, peak intensity I, and temporal duration of the pulse. This dichroic effect (i.e., the difference of the two-electron angular distributions for opposite helicities of the ionizing XUV pulse) originates from interference of first- and second-order PT amplitudes, allowing one to probe and control S- and D-wave channels of the two-electron continuum. We show that the back-to-back in-plane geometry with unequal energy sharing is an ideal one for observing this dichroic effect that occurs only for an elliptically polarized, few-cycle attosecond pulse.

Efficient degradation of H2S over transition metal modified TiO2 under VUV irradiation: Performance and mechanism

Science.gov (United States)

Liu, Gaoyuan; Ji, Jian; Hu, Peng; Lin, Sixin; Huang, Haibao

2018-03-01

Odor pollution causes great harm to the atmospheric environment and human health. H2S, as an odor gas, is highly toxic and corrosive and thus requires removal efficiently. In this study, TiO2 catalysts modified by transition metals including Mn, Cu, Ni and Co, were prepared using a modified sol-gelatin method and tested under UV-PCO or VUV-PCO process. H2S degradation was great enhanced in VUV-PCO compared with conventional UV-PCO. Among the catalysts, 1 wt% Mn-TiO2 showed the highest removal efficiency of 89.9%, which is 30 times higher than that under 254 nm UV irradiation. Residual ozone in the outlet can be completely eliminated by Mn-TiO2. Photocatalytic oxidation, photolysis and ozone-assisted catalytic oxidation all involved in the VUV-PCO process and their contribution were determined by H2S removal efficiency.

Airfoil sampling of a pulsed Laval beam with tunable vacuum ultraviolet synchrotron ionization quadrupole mass spectrometry: application to low-temperature kinetics and product detection.

Science.gov (United States)

Soorkia, Satchin; Liu, Chen-Lin; Savee, John D; Ferrell, Sarah J; Leone, Stephen R; Wilson, Kevin R

2011-12-01

A new pulsed Laval nozzle apparatus with vacuum ultraviolet (VUV) synchrotron photoionization quadrupole mass spectrometry is constructed to study low-temperature radical-neutral chemical reactions of importance for modeling the atmosphere of Titan and the outer planets. A design for the sampling geometry of a pulsed Laval nozzle expansion has been developed that operates successfully for the determination of rate coefficients by time-resolved mass spectrometry. The new concept employs airfoil sampling of the collimated expansion with excellent sampling throughput. Time-resolved profiles of the high Mach number gas flow obtained by photoionization signals show that perturbation of the collimated expansion by the airfoil is negligible. The reaction of C(2)H with C(2)H(2) is studied at 70 K as a proof-of-principle result for both low-temperature rate coefficient measurements and product identification based on the photoionization spectrum of the reaction product versus VUV photon energy. This approach can be used to provide new insights into reaction mechanisms occurring at kinetic rates close to the collision-determined limit.

Laser-plasma sourced, temperature dependent, VUV spectrophotometer using dispersive analysis

International Nuclear Information System (INIS)

French, R.H.

1990-01-01

We have developed a vacuum ultraviolet spectrophotometer with wide energy and temperature range coverage, utilizing a laser-plasma light source (LPLS), CO 2 -laser sample heating and time-resolved dispersive analysis. Reflection and transmission spectra can be taken from 1.7 to 40 eV (31-700 nm) on samples at 15-1800 K with a time resolution of 20-400 ns. These capabilities permit the study of the temperature dependence of the electronic structure, encompassing the effects of thermal lattice expansion and electron-phonon interaction, and changes in the electronic structure associated with equilibrium and metastable phase transitions and stress relaxation. The LPLS utilizes a samarium laser-plasma created by a Q-switched Nd:YAG laser (500 mJ/pulse) to produce high brightness, stable, continuum radiation. The spectrophotometer is of a single beam design using calibrated iridium reference mirrors. White light is imaged off the sample in to the entrance slit of a 1-m polychromator. The resolution is 0.1 to 0.3 nm. The dispersed light is incident on a focal plane phosphor, fiber-optic-coupled to an image-intensified reticon detector. For spectroscopy between 300 and 1800 K, the samples are heated in situ with a 150 Watt CO 2 laser. The signal to noise ratio in the VUV, for samples at 1800 K, is excellent. From 300 K to 15 K samples are cooled using a He cryostat. (orig.)

Atomic and molecular effects in the VUV spectra of solids

International Nuclear Information System (INIS)

Sonntag, B.

1977-10-01

The VUV spectra of solids are often dominated by atomic or molecular effects, which clearly manifest themselves in the gross features of the spectra and the fine structure at inner shell excitation thresholds. Evidence for the influence of atomic and molecular matrix elements, multiplet-splitting and correlation is presented. Special emphasis is given to the direct experimental verification based on the comparison of atomic and solid state spectra. (orig.) [de

The effects of low-intensity pulsed ultrasound on tendon-bone healing in a transosseous-equivalent sheep rotator cuff model.

Science.gov (United States)

Lovric, Vedran; Ledger, Michael; Goldberg, Jerome; Harper, Wade; Bertollo, Nicky; Pelletier, Matthew H; Oliver, Rema A; Yu, Yan; Walsh, William R

2013-02-01

The purpose of this study was to examine the effects Low-intensity Pulsed Ultrasound has on initial tendon-bone healing in a clinically relevant extra-articular transosseous-equivalent ovine rotator cuff model. Eight skeletally mature wethers, randomly allocated to either control group (n = 4) or treatment group (n = 4), underwent rotator cuff surgery following injury to the infraspinatus tendon. All animals were killed 28 days post surgery to allow examination of early effects of Low-intensity Pulsed Ultrasound treatment. General improvement in histological appearance of tendon-bone integration was noted in the treatment group. Newly formed woven bone with increased osteoblast activity along the bone surface was evident. A continuum was observed between the tendon and bone in an interdigitated fashion with Sharpey's fibres noted in the treatment group. Low-intensity Pulsed Ultrasound treatment also increased bone mineral density at the tendon-bone interface (p < 0.01), while immunohistochemistry results revealed an increase in the protein expression patterns of VEGF (p = 0.038), RUNX2 (p = 0.02) and Smad4 (p = 0.05). The results of this study indicate that Low-intensity Pulsed Ultrasound may aid in the initial phase of tendon-bone healing process in patients who have undergone rotator cuff repair. This treatment may also be beneficial following other types of reconstructive surgeries involving the tendon-bone interface.

Effect of the temporal laser pulse asymmetry on pair production processes during intense laser-electron scattering

Science.gov (United States)

Hojbota, C. I.; Kim, Hyung Taek; Kim, Chul Min; Pathak, V. B.; Nam, Chang Hee

2018-06-01

We investigate the effects of laser pulse shape on strong-field quantum electrodynamics (QED) processes during the collision between a relativistic electron beam and an intense laser pulse. The interplay between high-energy photon emission and two pair production processes, i.e. nonlinear Breit–Wheeler (BW) and Trident, was investigated using particle-in-cell simulations. We found that the temporal evolution of these two processes could be controlled by using laser pulses with different degrees of asymmetry. The temporal envelope of the laser pulse can significantly affect the number of pairs coming from the Trident process, while the nonlinear BW process is less sensitive to it. This study shows that the two QED processes can be examined with state-of-the-art petawatt lasers and the discrimination of the two pair creation processes is feasible by adjusting the temporal asymmetry of the colliding laser pulse.

Dynamics of a collisionless plasma interacting with an ultra-intense laser pulse

International Nuclear Information System (INIS)

Capdessus, Remi

2013-01-01

The interaction of a plasma with an ultra-intense laser pulse becomes more and more interesting as a result of the advances made in terms of numerical tools laser technology. The radiation reaction impacts the electrons dynamics, those of the synchrotron radiation as well as those of the ions by means of charge separation field, for laser intensities above 10 22 W/cm 2 . The kinetic equations governing the particles transport at ultra-high intensity have been obtained. The radiation reaction involves the shrinkage of the space volume of the electrons phases. It has been shown with numerical simulations the strong retro-action that the collective effects induce on the synchrotron radiation generated by the accelerated electrons. The importance of the collective effects depends strongly on the ions mass and of the thickness of the considered plasma. These effects could be verified experimentally with hydrogen cryogenic targets. (author) [fr

Variational analysis of self-focusing of intense ultrashort pulses in gases

International Nuclear Information System (INIS)

Arevalo, E.; Becker, A.

2005-01-01

By using perturbation theory we derive an expression for the electrical field of a Gaussian laser beam propagating in a gas medium. This expression is used as a trial solution in a variational method to get quasianalytical solutions for the width, intensity, and self-focusing distance. The approximation gives a better agreement with results of numerical simulations for a broad range of values of the input power than previous analytical results available in the literature. The results apply in the case of ultrashort pulses too

An empirical method for determination of elemental components of radiated powers and impurity concentrations from VUV and XUV spectral features in tokamak plasmas

International Nuclear Information System (INIS)

Lawson, K.; Peacock, N.; Gianella, R.

1998-12-01

The derivation of elemental components of radiated powers and impurity concentrations in bulk tokamak plasmas is complex, often requiring a full description of the impurity transport. A novel, empirical method, the Line Intensity Normalization Technique (LINT) has been developed on the JET (Joint European Torus) tokamak to provide routine information about the impurity content of the plasma and elemental components of radiated power (P rad ). The technique employs a few VUV and XUV resonance line intensities to represent the intrinsic impurity elements in the plasma. From a data base comprising these spectral features, the total bolometric measurement of the radiated power and the Z eff measured by visible spectroscopy, separate elemental components of P rad and Z eff are derived. The method, which converts local spectroscopic signals into global plasma parameters, has the advantage of simplicity, allowing large numbers of pulses to be processed, and, in many operational modes of JET, is found to be both reliable and accurate. It relies on normalizing the line intensities to the absolute calibration of the bolometers and visible spectrometers, using coefficients independent of density and temperature. Accuracies of the order of ± 15% can be achieved for the elemental P rad components of the most significant impurities and the impurity concentrations can be determined to within ±30%. Trace elements can be monitored, although with reduced accuracy. The present paper deals with limiter discharges, which have been the main application to date. As a check on the technique and to demonstrate the value of the LINT results, they have been applied to the transport modelling of intrinsic impurities carried out with the SANCO transport code, which uses atomic data from ADAS. The simulations provide independent confirmation of the concentrations empirically derived using the LINT technique. For this analysis, the simple case of the L-mode regime is considered, the chosen

Impact of intense x-ray pulses on a NaI(Tl)-based gamma camera

Science.gov (United States)

Koppert, W. J. C.; van der Velden, S.; Steenbergen, J. H. L.; de Jong, H. W. A. M.

2018-03-01

In SPECT/CT systems x-ray and γ-ray imaging is performed sequentially. Simultaneous acquisition may have advantages, for instance in interventional settings. However, this may expose a gamma camera to relatively high x-ray doses and deteriorate its functioning. We studied the NaI(Tl) response to x-ray pulses with a photodiode, PMT and gamma camera, respectively. First, we exposed a NaI(Tl)-photodiode assembly to x-ray pulses to investigate potential crystal afterglow. Next, we exposed a NaI(Tl)-PMT assembly to 10 ms LED pulses (mimicking x-ray pulses) and measured the response to flashing LED probe-pulses (mimicking γ-pulses). We then exposed the assembly to x-ray pulses, with detector entrance doses of up to 9 nGy/pulse, and analysed the response for γ-pulse variations. Finally, we studied the response of a Siemens Diacam gamma camera to γ-rays while exposed to x-ray pulses. X-ray exposure of the crystal, read out with a photodiode, revealed 15% afterglow fraction after 3 ms. The NaI(Tl)-PMT assembly showed disturbances up to 10 ms after 10 ms LED exposure. After x-ray exposure however, responses showed elevated baselines, with 60 ms decay-time. Both for x-ray and LED exposure and after baseline subtraction, probe-pulse analysis revealed disturbed pulse height measurements shortly after exposure. X-ray exposure of the Diacam corroborated the elementary experiments. Up to 50 ms after an x-ray pulse, no events are registered, followed by apparent energy elevations up to 100 ms after exposure. Limiting the dose to 0.02 nGy/pulse prevents detrimental effects. Conventional gamma cameras exhibit substantial dead-time and mis-registration of photon energies up to 100 ms after intense x-ray pulses. This is due PMT limitations and due to afterglow in the crystal. Using PMTs with modified circuitry, we show that deteriorative afterglow effects can be reduced without noticeable effects on the PMT performance, up to x-ray pulse doses of 1 nGy.

National Synchrotron Light Source users manual: Guide to the VUV and x-ray beam lines

International Nuclear Information System (INIS)

Gmuer, N.F.; White-DePace, S.M.

1987-08-01

The success of the National Synchrotron Light Source in the years to come will be based, in large part, on the size of the users community and the diversity of the scientific disciplines represented by these users. In order to promote this philosophy, this National Synchrotron Light Source (NSLS) Users Manual: Guide to the VUV and X-Ray Beam Lines, has been published. This manual serves a number of purposes. In an effort to attract new research, it will present to the scientific community-at-large the current and projected architecture and capabilities of the various VUV and x-ray beam lines and storage rings. We anticipate that this publication will be updated periodically in order to keep pace with the constant changes at the NSLS

Time-resolved VUV spectroscopy in the EXTRAP-T2 reversed field pinch

Science.gov (United States)

Hedqvist, Anders; Rachlew-Källne, Elisabeth

1998-09-01

Time-resolved VUV spectroscopy has been used to investigate the effects of impurities in a reversed field pinch operating with a resistive shell. Results of electron temperature, impurity ion densities, particle confinement time and 0741-3335/40/9/004/img1 together with a description of the interpretation and the equipment are presented.

Pulse pile-up. I: Short pulses

International Nuclear Information System (INIS)

Wilkinson, D.H.

1990-07-01

The search for rare large pulses against an intense background of smaller ones involves consideration of pulse pile-up. Approximate methods are presented, based on ruin theory, by which the probability of such pile-up may be estimated for pulses of arbitrary form and of arbitrary pulse-height distribution. These methods are checked against cases for which exact solutions are available. The present paper is concerned chiefly with short pulses of finite total duration. (Author) (5 refs., 24 figs.)

Photodissociation of Small Molecules and Photoionization of Free Radicals Using the VUV Velocity-Map Imaging Photoion and Photoelectron Method

Science.gov (United States)

Gao, Hong

The tunable vacuum ultraviolet (VUV) laser generated through the two-photon resonance-enhanced four-wave mixing scheme is combined with the newly developed time-slice velocity map imaging photoion method to study the photodissociation of small molecules in the VUV region, and with the velocity map imaging photoelectron method to study the photoionization of free radicals. The photodissociation dynamics of NO in the energy region around 13.5 eV has been investigated. Branching ratios of the three lowest dissociation channels of 12C 16O that produce C(3P) + O(3P), C( 1D) + O(3P) and C(3P) + O(1D) are measured for the first time in the VUV region from 102,500 cm-1 to 110,500 cm-1, valuable information of the dissociation dynamics for this prototype system has been deduced. We demonstrated an experiment that has two independently tunable VUV lasers and a time-slice velocity map imaging setup, this provides us a global way to perform systematic state-selected photodissociation of small molecules via state-selected detection of the atomic products in the VUV region. The velocity map imaging photoelectron method was successfully used to obtain the photoelectron spectrum of the propargyl radical (C3H3) via a single VUV photoionization process. The propargyl radical is generated by the 193 nm laser photodissociation of the precursor C3H3Cl. This is the first time that the velocity map imaging photoelectron method is used to get the photoelectron spectra of free radicals, indicating that it is a powerful technique for studying the photoionization of free radicals which are always hard to be produced with high enough number densities for spectroscopic studies. This dissertation is mainly based on the following peer-reviewed journal articles: 1. Hong Gao, Yang Pan, Lei Yang, Jingang Zhou, C. Y. Ng and William M. Jackson. "Time-slice velocity-map ion imaging studies of the Photodissociation of NO in the vacuum ultraviolet region", the Journal of Chemical Physics, 136, 134302

Storage-ring FEL for the vuv

International Nuclear Information System (INIS)

Peterson, J.M.; Bisognano, J.J.; Garren, A.A.; Halbach, K.; Kim, K.J.; Sah, R.C.

1984-09-01

A free-electron laser for the vuv operating in a storage ring requires an electron beam of high density and low energy spread and a short wavelength, narrow-gap undulator. These conditions tend to produce longitudinal and transverse beam instabilities, excessive beam growth through multiple intrabeam scattering, and a short gas-scattering lifetime. Passing the beam only occasionally through the undulator in a by-pass straight section, as proposed by Murphy and Pellegrini, allows operation in a high-gain, single-pass mode and a long gas-scattering lifetime. Several storage ring designs have been considered to see how best to satisfy the several requirements. Each features a by-pass, a low-emittance lattice, and built-in wigglers for enhanced damping to counteract the intra-beam scattering. 15 references, 3 figures, 2 tables

Uncooled Radiation Hard SiC Schottky VUV Detectors Capable of Single Photon Sensing, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — This project seeks to design, fabricate, characterize and commercialize very large area, uncooled and radiative hard 4H-SiC VUV detectors capable of near single...

Experimental platform for investigations of high-intensity laser plasma interactions in the magnetic field of a pulsed power generator

Science.gov (United States)

Ivanov, V. V.; Maximov, A. V.; Swanson, K. J.; Wong, N. L.; Sarkisov, G. S.; Wiewior, P. P.; Astanovitskiy, A. L.; Covington, A. M.

2018-03-01

An experimental platform for the studying of high-intensity laser plasma interactions in strong magnetic fields has been developed based on the 1 MA Zebra pulsed power generator coupled with the 50-TW Leopard laser. The Zebra generator produces 100-300 T longitudinal and transverse magnetic fields with different types of loads. The Leopard laser creates plasma at an intensity of 1019 W/cm2 in the magnetic field of coil loads. Focusing and targeting systems are integrated in the vacuum chamber of the pulsed power generator and protected from the plasma debris and strong mechanical shock. The first experiments with plasma at laser intensity >2 × 1018 W/cm2 demonstrated collimation of the laser produced plasma in the axial magnetic field strength >100 T.

Photofragmentation spectra of halogenated methanes in the VUV photon energy range

Energy Technology Data Exchange (ETDEWEB)

Cartoni, Antonella, E-mail: antonella.cartoni@uniroma1.it [Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, P.le Aldo Moro 5, Roma 00185 (Italy); Bolognesi, Paola; Fainelli, Ettore; Avaldi, Lorenzo [CNR-IMIP, Area della Ricerca di Roma 1, Monterotondo Scalo (Rm) 00015 (Italy)

2014-05-14

In this paper an investigation of the photofragmentation of dihalomethanes CH{sub 2}X{sub 2} (X = F, Cl, Br, I) and chlorinated methanes (CH{sub n}Cl{sub 4−n} with n = 0–3) with VUV helium, neon, and argon discharge lamps is reported and the role played by the different halogen atoms is discussed. Halogenated methanes are a class of molecules used in several fields of chemistry and the study of their physical and chemical proprieties is of fundamental interest. In particular their photodissociation and photoionization are of great importance since the decomposition of these compounds in the atmosphere strongly affects the environment. The results of the present work show that the halogen-loss is the predominant fragmentation channel for these molecules in the VUV photon energy range and confirm their role as reservoir of chlorine, bromine, and iodine atoms in the atmosphere. Moreover, the results highlight the peculiar feature of CH{sub 2}F{sub 2} as a source of both fluorine and hydrogen atoms and the characteristic formation of I{sub 2}{sup +} and CH{sub 2}{sup +} ions from the photofragmentation of the CH{sub 2}I{sub 2} molecule.

Intensive neutron source based on powerful electron linear accelerator LIA-30 and pulsed nuclear reactor FR-1

Energy Technology Data Exchange (ETDEWEB)

Bossamykin, V S; Koshelev, A S; Gerasimov, A I; Gordeev, V S; Grishin, A V; Averchenkov, V Ya; Lazarev, S A; Maslov, G N; Odintsov, Yu M [All-Russian Scientific Research Institute of Experimental Physics, Sarov (Russian Federation)

1997-12-31

Some results are given of investigations on joint operation modes of the linear induction electron accelerator LIA-30 ({approx} 40 MeV, {approx} 100 kA, {approx} 20 ns) and the pulsed reactor FR-1 with a compact metal core, aimed at achieving high intensity neutron fluxes. The multiplication factor Q for prompt neutrons in the FR-1 booster mode operation increased from 100 to 4500. The total output of prompt neutrons from FR-1 at Q = 2570 was 1.4 x 10{sup 16} 1/pulse with a pulse half width of {approx} 25 {mu}s. (author). 4 figs., 4 refs.

Study of the absorption and energy transfer processes in inorganic luminescent materials in the UV and VUV region; Etude des processus d`absorption et de transfert d`energie au sein de materiaux inorganiques luminescents dans le domaine UV et VUV

Energy Technology Data Exchange (ETDEWEB)

Mayolet, A

1995-11-29

In order to find a green emitting phosphor showing high quantum efficiency and a short decay time which can be used in the color Plasma Display Panels developed by Thomson-TTE-TIV company, a VUV spectrophotometer built at IPN Orsay, using the synchrotron radiation from the SUPER-ACO storage ring as an excitation source, allow us the simultaneous recording of the luminescence excitation and diffuse reflectivity spectra of the inorganic compounds in the UV-VUV range. In addition, this experimental set-up enable us to determine the luminescence quantum efficiency of phosphors in the whole energy range of investigation. The chemical synthesis of rare-earth ortho-- and metaborate and rare-earth ortho- and metaphosphate doped with trivalent lanthanide ions cerium, praseodymium, europium and terbium have been made. The energy variation of the thresholds of the luminescence excitation mechanisms in function of the nature and the structure of the host matrix is discussed. We have determined the influence of the nephelauxetic effect and the crystal field intensity on the energy of the f-d inter-configuration transitions. The variation of the luminescence quantum efficiency of the dopant ion is interpreted through the `impurity bound exciton` model. The systematic comparison of the cerium and terbium trivalent ions spectroscopic properties in the Y(AG)G host lattice series stands to reason that the self-ionized state of the luminescent center plays an important role in the rate of the non radiative relaxation. It is the redox power of the host matrix which imposes to the luminescent center, the energy of this state. (author) 134 refs.

Interaction of intense ultrashort pulse lasers with clusters

International Nuclear Information System (INIS)

Petrov, G. M.; Davis, J.

2008-01-01

The dynamics of clusters composed of different material irradiated by a high-intensity ultrashort pulse laser was studied using a fully relativistic three-dimensional molecular dynamics model. Key parameters of the cluster evolution such as particle positions, energy absorption, and cluster explosion were simulated. By a direct comparison of these parameters for clusters of equal initial radius but made of different material (deuterium, neon, argon, and xenon), the main stages and attributes of cluster evolution were elucidated. The simulations showed that clusters made of different material act alike, especially those of heavy elements. Clusters made of heavy elements (neon, argon, and xenon) differentiate from clusters made of light elements (deuterium) by the magnitude of the absorbed energy per cluster and the final mean energy of exploding ions. What most distinguishes clusters composed of different material is the amount of emitted radiation and its spectral range

Long-pulsed dye laser versus intense pulsed light for photodamaged skin: A randomized split-face trial with blinded response evaluation

DEFF Research Database (Denmark)

Jorgensen, G.F.; Hedelund, L.; Haedersdal, M.

2008-01-01

Objective: In a randomized controlled split-face trial to evaluate efficacy and adverse effects from rejuvenation with long-pulsed dye laser (LPDL) versus intense pulsed light (IPL). Materials and Methods: Twenty female volunteers with Fitzpatrick skin types I-III, classes I-II rhytids......, and symmetrical split-face photodamage were included in the study. Subjects received a series of three treatments at 3-week intervals with half-face LPDL (V-beam Perfecta, 595 nm, Candela Laser Corporation) and half-face IPL (Ellipse Flex, Danish Dermatologic Development); the interventions being randomly...... assigned to left and right sides. Primary end-points were telangiectasias, irregular pigmentation and preferred treatment. Secondary end-points were skin texture, rhytids, pain, and adverse effects. Efficacy was evaluated by patient self-assessments and by blinded clinical on-site and photographic...

Characteristics and performance of the Los Alamos VUV beamline at the NSLS

International Nuclear Information System (INIS)

Bartlett, R.J.; Trela, W.J.; Michaud, F.D.; Southworth, S.H.; Alkire, R.W.; Roy, P.; Rothe, R.; Walsh, P.J.; Shinn, N.

1988-01-01

We describe the design and performance of the Los Alamos VUV synchrotron radiation beamline, U3C, on the VUV ring of the National Synchrotron Light Source at Brookhaven National Laboratory. The beamline uses separate function optics to collect and focus the horizontally and vertically diverging beam. The monochromator is a grazing incidence Rowland circle instrument of the extended grasshopper design (ERG). A postmonochromator refocusing mirror is used to focus or collimate the diverging beam from the monochromator. The beamline control and diagnostics systems are also discussed. Particular emphasis in the design has been placed on the reduction of stray and harmonic light. Higher order light is reduced by a grazing angle mirror low pass filter installed immediately downstream from the monochromator while stray light is reduced through the use of baffles and thin film filters. Also included in the line is a differential pumping section that permits gas phase and other experiments requiring pressures in the 10 -5 to 10 -4 Torr range to be coupled to the beamline. (orig.)

The intense pulsed light systems : new treatment possibilities for vascular, pigmented lesions and hair removal

NARCIS (Netherlands)

C.A. Schroeter (Careen)

2004-01-01

textabstractGiven all of the differences in between laser and IPLS devices and the need for additional information in IPLS treatment applications, the aim of this study was to evaluate new treatment possibilities using Intense Pulsed Light Sources and to address the following questions: 1. What

Reduction of protease activity in milk by continuous flow high-intensity pulsed electric field treatments.

Science.gov (United States)

Bendicho, S; Barbosa-Cánovas, G V; Martín, O

2003-03-01

High-intensity pulsed electric field (HIPEF) is a non-thermal food processing technology that is currently being investigated to inactivate microorganisms and certain enzymes, involving a limited increase of food temperature. Promising results have been obtained on the inactivation of microbial enzymes in milk when suspended in simulated milk ultrafiltrate. The aim of this study was to evaluate the effectiveness of continuous HIPEF equipment on inactivating a protease from Bacillus subtilis inoculated in milk. Samples were subjected to HIPEF treatments of up to 866 micros of squared wave pulses at field strengths from 19.7 to 35.5 kV/cm, using a treatment chamber that consisted of eight colinear chambers connected in series. Moreover, the effects of different parameters such as pulse width (4 and 7 micros), pulse repetition rates (67, 89, and 111 Hz), and milk composition (skim and whole milk) were tested. Protease activity decreased with increased treatment time or field strength and pulse repetition rate. Regarding pulse width, no differences were observed between 4 and 7 micros pulses when total treatment time was considered. On the other hand, it was observed that milk composition affected the results since higher inactivation levels were reached in skim than in whole milk. The maximum inactivation (81%) was attained in skim milk after an 866-micros treatment at 35.5 kV/cm and 111 Hz.

Intense Non-Linear Soft X-Ray Emission from a Hydride Target during Pulsed D Bombardment

Science.gov (United States)

Miley, George H.; Yang, Yang; Lipson, Andrei; Haque, Munima; Percel, Ian; Romer, Michael

Radiation emission from low-energy nuclear radiation (LENR) electrodes (both charged-particle and X-rays) represents an important feature of LENR in general. Here, calibration, measurement techniques, and soft X-ray emission results from deuterium bombardment of a Pd target (cathode) placed in a pulsed deuterium glow discharge (PGD) are described. An X-ray intensity of 13.4 mW/cm2 and a dose of 3.3 μJ/cm2 were calculated over a 0.5 ms pulse time from AXUV photodiode radiation detector measurements. A most striking feature is that X-ray energies >600 V are observed with a discharge voltage only about half of that value. To further investigate this phenomenon, emission during room temperature D-desorption from electrolytically loaded Pd:Dx cathodes was also studied. The X-ray emission energy observed was quite similar to the PGD case. However, the intensity in this case was almost 13 orders of magnitude lower due to the much lower deuterium fluxes involved.

Intense non-linear soft X-ray emission from a hydride target during pulsed D bombardment

International Nuclear Information System (INIS)

Miley, George H.; Yang, Yang; Lipson, Andrei; Haque, Munima; Percel, Ian; Romer, Michael

2006-01-01

Radiation emission from low-energy nuclear radiation (LENR) electrodes (both charged-particle and X-rays) represents an important feature of LENR in general. Here, calibration, measurement techniques, and soft X-ray emission results from deuterium bombardment of a Pd target (cathode) placed in a pulsed deuterium glow discharge (PGD) are described. An X-ray intensity of 13.4 mW/cm 2 and a dose of 3.3 μJ/cm 2 were calculated over a 0.5 ms pulse time from AXUV photodiode radiation detector measurements. A most striking feature is that X-ray energies >600 V are observed with a discharge voltage only about half of that value. To further investigate this phenomenon, emission during room temperature D-desorption from electrolytically loaded Pd:Dx cathodes was also studied. The X-ray emission energy observed was quite similar to the PGD case. However, the intensity in this case was almost 13 orders of magnitude lower due to the much lower deuterium fluxes involved. (author)

Study of the absorption and energy transfer processes in inorganic luminescent materials in the UV and VUV region

International Nuclear Information System (INIS)

Mayolet, A.

1995-01-01

In order to find a green emitting phosphor showing high quantum efficiency and a short decay time which can be used in the color Plasma Display Panels developed by Thomson-TTE-TIV company, a VUV spectrophotometer built at IPN Orsay, using the synchrotron radiation from the SUPER-ACO storage ring as an excitation source, allow us the simultaneous recording of the luminescence excitation and diffuse reflectivity spectra of the inorganic compounds in the UV-VUV range. In addition, this experimental set-up enable us to determine the luminescence quantum efficiency of phosphors in the whole energy range of investigation. The chemical synthesis of rare-earth ortho-- and metaborate and rare-earth ortho- and metaphosphate doped with trivalent lanthanide ions cerium, praseodymium, europium and terbium have been made. The energy variation of the thresholds of the luminescence excitation mechanisms in function of the nature and the structure of the host matrix is discussed. We have determined the influence of the nephelauxetic effect and the crystal field intensity on the energy of the f-d inter-configuration transitions. The variation of the luminescence quantum efficiency of the dopant ion is interpreted through the 'impurity bound exciton' model. The systematic comparison of the cerium and terbium trivalent ions spectroscopic properties in the Y(AG)G host lattice series stands to reason that the self-ionized state of the luminescent center plays an important role in the rate of the non radiative relaxation. It is the redox power of the host matrix which imposes to the luminescent center, the energy of this state. (author)

Collective Focusing of Intense Ion Beam Pulses for High-energy Density Physics Applications

International Nuclear Information System (INIS)

Dorf, Mikhail A.; Kaganovich, Igor D.; Startsev, Edward A.; Davidson, Ronald C.

2011-01-01

The collective focusing concept in which a weak magnetic lens provides strong focusing of an intense ion beam pulse carrying a neutralizing electron background is investigated by making use of advanced particle-in-cell simulations and reduced analytical models. The original analysis by Robertson Phys. Rev. Lett. 48, 149 (1982) is extended to the parameter regimes of particular importance for several high-energy density physics applications. The present paper investigates (1) the effects of non-neutral collective focusing in a moderately strong magnetic field; (2) the diamagnetic effects leading to suppression of the applied magnetic field due to the presence of the beam pulse; and (3) the influence of a finite-radius conducting wall surrounding the beam cross-section on beam neutralization. In addition, it is demonstrated that the use of the collective focusing lens can significantly simplify the technical realization of the final focusing of ion beam pulses in the Neutralized Drift Compression Experiment-I (NDCX-I), and the conceptual designs of possible experiments on NDCX-I are investigated by making use of advanced numerical simulations.

Terahertz radiation driven by two-color laser pulses at near-relativistic intensities: Competition between photoionization and wakefield effects

Science.gov (United States)

González de Alaiza Martínez, P.; Davoine, X.; Debayle, A.; Gremillet, L.; Bergé, L.

2016-01-01

We numerically investigate terahertz (THz) pulse generation by linearly-polarized, two-color femtosecond laser pulses in highly-ionized argon. Major processes consist of tunneling photoionization and ponderomotive forces associated with transverse and longitudinal field excitations. By means of two-dimensional particle-in-cell (PIC) simulations, we reveal the importance of photocurrent mechanisms besides transverse and longitudinal plasma waves for laser intensities >1015 W/cm2. We demonstrate the following. (i) With two-color pulses, photoionization prevails in the generation of GV/m THz fields up to 1017 W/cm2 laser intensities and suddenly loses efficiency near the relativistic threshold, as the outermost electron shell of ionized Ar atoms has been fully depleted. (ii) PIC results can be explained by a one-dimensional Maxwell-fluid model and its semi-analytical solutions, offering the first unified description of the main THz sources created in plasmas. (iii) The THz power emitted outside the plasma channel mostly originates from the transverse currents. PMID:27255689

Effect of the light spectrum of various substrates for inkjet printed conductive structures sintered with intense pulsed light

International Nuclear Information System (INIS)

Weise, Dana; Mitra, Kalyan Yoti; Ueberfuhr, Peter; Baumann, Reinhard R.

2015-01-01

In this work, the novel method of intense pulsed light (IPL) sintering of a nanoparticle silver ink is presented. Various patterns are printed with the Inkjet technology on two flexible foils with different light spectra. One is a clear Polyethylenterephthalat [PET] foil and the second is a light brownish Polyimide [PI] foil. The samples are flashed with different parameters regarding to pulse intensity and pulse length. Microscopic images are indicating the impact of the flashing parameters and the different light spectra of the substrates on the sintered structures. Sheet and line resistance are measured and the conductivity is calculated. A high influence of the property of the substrate with respect to light absorption and thermal conductivity on the functionality of printed conductive structures could be presented. With this new method of IPL sintering, highly conductive inkjet printed silver patterns could be manufactured within milliseconds on flexible polymeric foils without damaging the substrate

Generation of ultra-intense and ultra-short laser pulses with high temporal contrast; Generation d'impulsions laser ultra-breves et ultra-intenses a contraste temporel eleve

Energy Technology Data Exchange (ETDEWEB)

Julien, A

2006-03-15

The topic of this thesis work concerns the design and the characterization of an efficient device devoted to the temporal contrast improvement for ultra-intense femtosecond laser pulses. The contrast is defined as the intensity ratio between the main femtosecond pulse and its nanosecond pedestal. This pedestal is the amplified spontaneous emission (ASE), inherent with laser amplification mechanism. The ASE background has dramatic effects for laser-matter interactions on a solid target. The presented work consists in the theoretical and experimental study of a temporal filter based on a third order nonlinear effect acting on the pulse polarization. We have studied several kinds of nonlinear filters. The selected device is based on the process of cross-polarized wave generation (XPW) in crystals with an anisotropic third-order nonlinear susceptibility. This nonlinear filter has been experimented on various femtosecond systems. It allows a contrast improvement of several orders of magnitude, as demonstrated by temporal profiles measurements on a large intensity dynamic. A device to improve the nonlinear process conversion efficiency, it means the filter transmission, has also been achieved. This method is based on constructive interferences between XPW signals generated in different crystals. This setup has made it possible to reach experimentally the maximum theoretical efficiency ( >20%) and in the same time ensures the system stability. At least, we have demonstrated that the filter preserves, or even improves, spectral and spatial qualities of the laser pulse. These results are thus particularly promising and allow contemplating the implementation of the filter in current femtosecond systems. (author)

Neutron production enhancements for the Intense Pulsed Neutron Source.

Energy Technology Data Exchange (ETDEWEB)

Iverson, E. B.

1999-01-04

The Intense Pulsed Neutron Source (IPNS) was the first high energy spallation neutron source in the US dedicated to materials research. It has operated for sixteen years, and in that time has had a very prolific record concerning the development of new target and moderator systems for pulsed spallation sources. IPNS supports a very productive user program on its thirteen instruments, which are oversubscribed by more than two times, meanwhile having an excellent overall reliability of 95%. Although the proton beam power is relatively low at 7 kW, the target and moderator systems are very efficient. The typical beam power which gives an equivalent flux for long-wavelength neutrons is about 60 kW, due to the use of a uranium target and liquid and solid methane moderators, precluded at some sources due to a higher accelerator power. The development of new target and moderator systems is by no means stagnant at IPNS. They are presently considering numerous enhancements to the target and moderators that offer prospects for increasing the useful neutron production by substantial factors. Many of these enhancements could be combined, although their combined benefit has not yet been well established. Meanwhile, IPNS is embarking on a coherent program of study concerning these improvements and their possible combination and implementation. Moreover, any improvements accomplished at IPNS would immediately increase the performance of IPNS instruments.

Neutron production enhancements for the Intense Pulsed Neutron Source

International Nuclear Information System (INIS)

Iverson, E. B.

1999-01-01

The Intense Pulsed Neutron Source (IPNS) was the first high energy spallation neutron source in the US dedicated to materials research. It has operated for sixteen years, and in that time has had a very prolific record concerning the development of new target and moderator systems for pulsed spallation sources. IPNS supports a very productive user program on its thirteen instruments, which are oversubscribed by more than two times, meanwhile having an excellent overall reliability of 95%. Although the proton beam power is relatively low at 7 kW, the target and moderator systems are very efficient. The typical beam power which gives an equivalent flux for long-wavelength neutrons is about 60 kW, due to the use of a uranium target and liquid and solid methane moderators, precluded at some sources due to a higher accelerator power. The development of new target and moderator systems is by no means stagnant at IPNS. They are presently considering numerous enhancements to the target and moderators that offer prospects for increasing the useful neutron production by substantial factors. Many of these enhancements could be combined, although their combined benefit has not yet been well established. Meanwhile, IPNS is embarking on a coherent program of study concerning these improvements and their possible combination and implementation. Moreover, any improvements accomplished at IPNS would immediately increase the performance of IPNS instruments

Studying Intense Pulsed Light Method Along With Corticosteroid Injection in Treating Keloid Scars

OpenAIRE

Shamsi Meymandi, Simin; Rezazadeh, Azadeh; Ekhlasi, Ali

2014-01-01

Background: Results of various studies suggest that the hypertrophic and keloid scars are highly prevalent in the general population and are irritating both physically and mentally. Objective: Considering the variety of existing therapies, intense pulsed light (IPL) method along with corticosteroid injection was evaluated in treating these scars. Materials and Methods: 86 subjects were included in this clinical trial. Eight sessions of therapeutic intervention were done with IPL along with co...

Efficacy of low-intensity pulsed ultrasound in the prevention of osteoporosis following spinal cord injury.

Science.gov (United States)

Warden, S J; Bennell, K L; Matthews, B; Brown, D J; McMeeken, J M; Wark, J D

2001-11-01

Ultrasound (US), a high-frequency acoustic energy traveling in the form of a mechanical wave, represents a potential site-specific intervention for osteoporosis. Bone is a dynamic tissue that remodels in response to applied mechanical stimuli. As a form of mechanical stimulation, US is anticipated to produce a similar remodeling response. This theory is supported by growing in vitro and in vivo evidence demonstrating an osteogenic effect of pulsed-wave US at low spatial-averaged temporal-averaged intensities. The aim of this study was to investigate whether low-intensity pulsed US could prevent calcaneal osteoporosis in individuals following spinal cord injury (SCI). Fifteen patients with a 1-6 month history of SCI were recruited. Active US was introduced to one heel for 20 min/day, 5 days/week, over 6 weeks. The contralateral heel was simultaneously treated with inactive US. Patients were blind to which heel was being actively treated. Active US pulsed with a 10 microsec burst of 1.0 MHz sine waves repeating at 3.3 kHz. The spatial-averaged temporal-averaged intensity was set at 30 mW/cm(2). Bone status was assessed at baseline and following the intervention period by dual-energy X-ray absorptiometry and quantitative US. SCI resulted in significant bone loss. Bone mineral content decreased by 7.5 +/- 3.0% in inactive US-treated calcanei (p 0.05). These findings confirm the negative skeletal impact of SCI, and demonstrate that US at the dose and mode administered was not a beneficial intervention for SCI-induced osteoporosis. This latter finding may primarily relate to the inability of US to effectively penetrate the outer cortex of bone due to its acoustic properties.

User oriented end-station on VUV pump-probe magneto-optical ellipsometry at ELI beamlines

Science.gov (United States)

Espinoza, Shirly; Neuber, Gerd; Brooks, Christopher D.; Besner, Bastian; Hashemi, Maryam; Rübhausen, Michael; Andreasson, Jakob

2017-11-01

A state of the art ellipsometer for user operations is being implemented at ELI Beamlines in Prague, Czech Republic. It combines three of the most promising and exotic forms of ellipsometry: VUV, pump-probe and magneto-optical ellipsometry. This new ellipsometer covers a spectral operational range from the NIR up to the VUV, with high through-put between 1 and 40 eV. The ellipsometer also allows measurements of magneto-optical spectra with a 1 kHz switchable magnetic field of up to 1.5 T across the sample combining ellipsometry and Kerr spectroscopy measurements in an unprecedented spectral range. This form of generalized ellipsometry enables users to address diagonal and off-diagonal components of the dielectric tensor within one measurement. Pump-probe measurements enable users to study the dynamic behaviour of the dielectric tensor in order to resolve the time-domain phenomena in the femto to 100 ns range.

Case histories of intense pulsed light phototherapy in dermatology - the HPPL™ and IFL™ technologies

Directory of Open Access Journals (Sweden)

Alessandro Martella

2017-06-01

Full Text Available The intense pulsed light (IPL and laser technologies are widely used for skin rejuvenation and for treating several dermatological disorders such as skin dyschromia and acne, and for non-ablative dermal remodeling of rhytides and hypertrophic scars. Technological evolution is rapid. The High Power Pulsed Light™ [HPPL™] and Incoherent Fast Light™ technologies [IFL™, Novavision Group S.p.A., 20826 Misinto (MB, Italy] are recent innovations in the field of IPL technologies; IFL™ is a further evolution of the already advanced HPPL™ system. The paper presents a selection of case histories of dermatological lesions treated with the HPPL™ and IFL™ technologies. All study materials were appropriately peer-reviewed for ethical problems.

High Harmonic Radiation Generation and Attosecond pulse generation from Intense Laser-Solid Interactions

Energy Technology Data Exchange (ETDEWEB)

Thomas, Alexander Roy [Univ. of Michigan, Ann Arbor, MI (United States); Krushelnick, Karl [Univ. of Michigan, Ann Arbor, MI (United States)

2016-09-08

We have studied ion motion effects in high harmonic generation, including shifts to the harmonics which result in degradation of the attosecond pulse train, and how to mitigate them. We have examined the scaling with intensity of harmonic emission. We have also switched the geometry of the interaction to measure, for the first time, harmonics from a normal incidence interaction. This was performed by using a special parabolic reflector with an on axis hole and is to allow measurements of the attosecond pulses using standard techniques. Here is a summary of the findings: First high harmonic generation in laser-solid interactions at 10²¹ Wcm^-2, demonstration of harmonic focusing, study of ion motion effects in high harmonic generation in laser-solid interactions, and demonstration of harmonic amplification.

Effects of high intensity pulsed electric field and thermal treatments on a lipase from Pseudomonas fluorescens.

Science.gov (United States)

Bendicho, S; Estela, C; Giner, J; Barbosa-Cánovas, G V; Martin, O

2002-01-01

Milk and dairy products may contain microorganisms capable of secreting lipases that cause sensory defects and technological problems in the dairy industry. In this study, the effects of thermal and high-intensity pulsed electric field (HIPEF) treatments on an extracellular lipase from Pseudomonas fluorescens, suspended in a simulated skim milk ultrafiltrate (SMUF) have been evaluated. Heat treatments applied were up to 30 min from 50 to 90 degrees C. HIPEF treatments were carried out using pilot plant facilities in a batch or continuous flow mode, where treatment chambers consisted of parallel and coaxial configuration, respectively. Samples were subjected to up to 80 pulses at electric field intensities ranging from 16.4 to 37.3 kV/cm. This resulted in a lipase that was quite resistant to heat and also to HIPEF. High (75 degrees C-15 s) and low pasteurization treatments (63 degrees C-30 min) led to inactivations of 5 and 20%, respectively. Using the batch-mode HIPEF equipment, a 62.1% maximum activity depletion was achieved after 80 pulses at 27.4 kV/cm. However, when HIPEF treatments were applied in the continuous flow mode, an inactivation rate of just 13% was achieved, after applying 80 pulses at 37.3 kV/cm and 3.5 Hz. The results of both heat and HIPEF treatments on enzyme inactivation were adjusted with good agreement to a first-order kinetic model (R2 > 62.3%).

Narrowband solid state vuv coherent source for laser cooling of antihydrogen

Energy Technology Data Exchange (ETDEWEB)

Michan, J. Mario [TRIUMF (Canada); Polovy, Gene; Madison, Kirk W. [The University of British Columbia, Department of Physics and Astronomy (Canada); Fujiwara, Makoto C. [TRIUMF (Canada); Momose, Takamasa, E-mail: momose@chem.ubc.ca [The University of British Columbia, Department of Chemistry, Department of Physics and Astronomy (Canada)

2015-11-15

We describe the design and performance of a solid-state pulsed source of narrowband (< 100 MHz) Lyman-α radiation designed for the purpose of laser cooling magnetically trapped antihydrogen. Our source utilizes an injection seeded Ti:Sapphire amplifier cavity to generate intense radiation at 729.4 nm, which is then sent through a frequency doubling stage and a frequency tripling stage to generate 121.56 nm light. Although the pulse energy at 121.56 nm is currently limited to 12 nJ with a repetition rate of 10 Hz, we expect to obtain greater than 0.1 μJ per pulse at 10 Hz by further optimizing the alignment of the pulse amplifier and the efficiency of the frequency tripling stage. Such a power will be sufficient for cooling a trapped antihydrogen atom from 500 mK to 20mK.

Long-pulsed Nd: YAG laser and intense pulse light-755 nm for idiopathic facial hirsutism: A comparative study

Directory of Open Access Journals (Sweden)

Arpit Shrimal

2017-01-01

Full Text Available Background: Hirsutism means excessive terminal hair growth in a female in male pattern distribution. Perception of hirsutism is subjective. Permanent laser hair reduction is a slow process taking many sessions and tracking of improvement parameters is tedious. Hence, a lot of confusion still exists regarding the type of laser most beneficial for treatment. Aim: The aim of this study was to compare the effectiveness and safety profile of long-pulsed Nd: YAG laser (1064 nm and intense pulse light (IPL-755 nm in management of idiopathic facial hirsutism. Settings and Design: Open-labelled, randomly allocated experimental study. Subjects and Methods: The study included 33 cases of idiopathic facial hirsutism. Patients were randomly divided into Group A, treated with long-pulsed Nd: YAG laser and Group B, treated with IPL-755 for a total of six sessions at 1 month interval. Statistical Analysis: Chi-square test was used in Medcalc® version 9.0 and the test of significance was taken to be P75% reduction in hair after six sessions in Group A was seen in fourteen (93.33% out of fifteen patients, whereas in Group B, it was seen only in three (16.66% out of eighteen patients. In Group A, erythema was seen in 26.67%, perifollicular edema and hyperpigmentation in 13.33% each. In Group B, erythema was seen in 50% patients, perifollicular edema in 16.67% and hyperpigmentation in 38.89% patients. Conclusions: Long-pulsed Nd: YAG Laser (1064 nm is better than IPL-755 nm in terms of safety and effectiveness in the management of idiopathic facial hirsutism.

Intense pulsed light vs. long-pulsed dye laser treatment of telangiectasia after radiotherapy for breast cancer: a randomized split-lesion trial of two different treatments

DEFF Research Database (Denmark)

Nymann, P.; Hedelund, L.; Hædersdal, Merete

2009-01-01

Background Chronic radiodermatitis is a common sequela of treatment for breast cancer and potentially a psychologically distressing factor for the affected women. Objectives To evaluate the efficacy and adverse effects of treatments with a long-pulsed dye laser (LPDL) vs. intense pulsed light (IPL......); the interventions were randomly assigned to left/right or upper/lower halves. Primary end-points were reduction in telangiectasia, patient satisfaction and preferred treatment. Secondary end-points were pain and adverse effects. Efficacy was registered by blinded photographic evaluations 3 months after the final...

High intensity pulsed electric field as an innovative technique for extraction of bioactive compounds-A review.

Science.gov (United States)

Yan, Liang-Gong; He, Lang; Xi, Jun

2017-09-02

How to extract bioactive compounds safely and efficiently is one of the problems for the food and pharmaceutical industry. In recent years, several novel extraction techniques have been proposed. To pursue a more efficient method for industrial production, high intensity pulsed electric field (HIPEF) extraction technique has been developed. HIPEF extraction technique, which is based on the conventional pulsed electric field (PEF), provided higher electric field intensity and a special continuous extraction system, and it has confirmed less extraction time, higher extraction yield, and mild processing temperature. So this innovative technique is promising for application of industrial production. This review was devoted to introducing the recent achievement of HIPEF extraction technique, including novel HIPEF continuous extraction system, principles and mechanisms; the critical process factors influencing its performance applications; and comparison of HIPEF extraction with other extraction techniques. In the end, the defects and future trends of HIPEF extraction were also discussed.

VUV and UV–vis optical study on KGd2F7 luminescent host doped with terbium and co-doped with europium

International Nuclear Information System (INIS)

Lisiecki, Radosław

2013-01-01

The KGd 2 F 7 :Tb and KGd 2 F 7 :Tb,Eu samples were obtained using a solid state reaction. Excitation spectra and emission spectra are reported and analyzed within the VUV–UV–vis spectral range. The intense green luminescence is observed in the KGd 2 F 7 :Tb while the combined emission of terbium and europium in the KGd 2 F 7 :Tb,Eu covers substantially the region of white light. The materials under study can be effectively excited making use of intense f–d transitions of Tb 3+ in the VUV–UV region. Experimental lifetimes of luminescent levels have been measured and discussed. It was found that the considerable energy transfer from Tb 3+ to Eu 3+ occurs. -- Highlights: • The prospective green and white emitting phosphors. • The effective VUV and UV–vis excitation process. • The considerable energy transfer among optically active ions. • The influence of (Tb, Eu) co-doping on relaxation dynamic of excited states

Long-pulsed Nd:YAG laser vs. intense pulsed light for hair removal in dark skin: a randomized controlled trial.

Science.gov (United States)

Ismail, S A

2012-02-01

Although several lasers meet the wavelength criteria for selective follicular destruction, the treatment of darker skin phototypes is particularly challenging because absorption of laser energy by the targeted hairs is compromised by an increased concentration of epidermal melanin. To compare satisfaction level, safety and effectiveness of a long-pulsed Nd:YAG laser and intense pulsed light (IPL) in axillary hair reduction in subjects with dark skin. The study design was a within-patient, right-left, assessor-blinded, comparison of long-pulsed Nd:YAG laser and IPL. Fifty women (skin phototypes IV-VI) volunteered for removal of axillary hair. Five sessions at 4- to 6-week intervals were performed. Hair counts at both sides were compared at baseline and 6months after the last session. Final overall evaluations were performed by subjects and clinician at the end of the study. Satisfaction was scored for both devices. Thirty-nine women completed the study. At 6months, the decrease in hair counts on the laser side (79·4%, Pvs. pretreatment) was significantly (Pvs. pretreatment). Only temporary adverse effects were reported at both sides. Higher pain scores and more inflammation were reported with Nd:YAG laser; however, it was preferred by 29 volunteers (74%). Volunteers reported higher satisfaction score with Nd:YAG laser (PDark skin can be treated by both systems safely and effectively; however, long-pulsed (1064 nm) Nd:YAG laser is more effective as reported by both subjects and clinician. © 2011 The Authors. BJD © 2011 British Association of Dermatologists.

Intense isolated attosecond pulse generation from relativistic laser plasmas using few-cycle laser pulses

International Nuclear Information System (INIS)

Ma, Guangjin; Dallari, William; Borot, Antonin; Tsakiris, George D.; Veisz, Laszlo; Krausz, Ferenc; Yu, Wei

2015-01-01

We have performed a systematic study through particle-in-cell simulations to investigate the generation of attosecond pulse from relativistic laser plasmas when laser pulse duration approaches the few-cycle regime. A significant enhancement of attosecond pulse energy has been found to depend on laser pulse duration, carrier envelope phase, and plasma scale length. Based on the results obtained in this work, the potential of attaining isolated attosecond pulses with ∼100 μJ energy for photons >16 eV using state-of-the-art laser technology appears to be within reach

VME computer monitoring system of KEK-PS fast pulsed magnet currents and beam intensities

International Nuclear Information System (INIS)

Kawakubo, T.; Akiyama, A.; Kadokura, E.; Ishida, T.

1992-01-01

For beam transfer from the KEK-PS Linac to the Booster synchrotron ring and from the Booster to the Main ring, many pulse magnets have been installed. It is very important for the machine operation to monitor the firing time, rising time and peak value of the pulsed magnet currents. It is also very important for magnet tuning to obtain good injection efficiency of the Booster and the Main ring, and to observe the last circulating bunched beam in the Booster as well as the first circulating in the Main. These magnet currents and beam intensity signals are digitized by a digital oscilloscope with signal multiplexers, and then shown on a graphic display screen of the console via a VME computer. (author)

Dynamic energy spectrum and energy deposition in solid target by intense pulsed ion beams

Institute of Scientific and Technical Information of China (English)

Xiao Yu; Xiao-Yun Le; Zheng Liu; Jie Shen; Yu I.Isakova; Hao-Wen Zhong; Jie Zhang; Sha Yan; Gao-Long Zhang; Xiao-Fu Zhang

2017-01-01

A method for analyzing the dynamic energy spectrum of intense pulsed ion beam (IPIB) was proposed.Its influence on beam energy deposition in metal target was studied with IPIB produced by two types of magnetically insulated diodes (MID).The emission of IPIB was described with space charge limitation model,and the dynamic energy spectrum was further analyzed with time-of-flight method.IPIBs generated by pulsed accelerators of BIPPAB-450 (active MID) and TEMP-4M (passive MID) were studied.The dynamic energy spectrum was used to deduce the power density distribution of IPIB in the target with Monte Carlo simulation and infrared imaging diagnostics.The effect on the distribution and evolution of thermal field induced by the characteristics of IPIB dynamic energy spectrum was discussed.

Measurement of impurity emission profiles in CHS Plasma using AXUV photodiode arrays and VUV bandpass filters

International Nuclear Information System (INIS)

Suzuki, C.; Peterson, B.J.; Ida, K.

2004-01-01

We have designed a compact and low-cost diagnostic system for spatiotemporal distributions of specific vacuum ultraviolet (VUV) emission lines from impurities in Compact Helical System (CHS) plasmas. The system consists of 20 channel absolute extreme ultraviolet photodiode arrays combined with interchangeable thin foil filters which have passbands in the VUV region. A compact mounting module which contains all the components including an in-vacuum preamplifier for immediate current-voltage conversion has been designed and successfully fabricated. A preliminary measurement with a single module using an aluminum foil filter has been carried out for monitoring the behavior of oxygen impurity in CHS, and initial results have been obtained. Two identical modules equipped with Versa Module European bus-based analog-digital converters will be available for future tomographic measurements

Tumour Cell Membrane Poration and Ablation by Pulsed Low-Intensity Electric Field with Carbon Nanotubes

Directory of Open Access Journals (Sweden)

Lijun Wang

2015-03-01

Full Text Available Electroporation is a physical method to increase permeabilization of cell membrane by electrical pulses. Carbon nanotubes (CNTs can potentially act like “lighting rods” or exhibit direct physical force on cell membrane under alternating electromagnetic fields thus reducing the required field strength. A cell poration/ablation system was built for exploring these effects of CNTs in which two-electrode sets were constructed and two perpendicular electric fields could be generated sequentially. By applying this system to breast cancer cells in the presence of multi-walled CNTs (MWCNTs, the effective pulse amplitude was reduced to 50 V/cm (main field/15 V/cm (alignment field at the optimized pulse frequency (5 Hz of 500 pulses. Under these conditions instant cell membrane permeabilization was increased to 38.62%, 2.77-fold higher than that without CNTs. Moreover, we also observed irreversible electroporation occurred under these conditions, such that only 39.23% of the cells were viable 24 h post treatment, in contrast to 87.01% cell viability without presence of CNTs. These results indicate that CNT-enhanced electroporation has the potential for tumour cell ablation by significantly lower electric fields than that in conventional electroporation therapy thus avoiding potential risks associated with the use of high intensity electric pulses.

Removing roughness on metal surface by irradiation of intense short-pulsed ion beams

International Nuclear Information System (INIS)

Hashimoto, Y.

1995-01-01

Surface modification of metals with an intense pulsed ion beam (IPIB) was studied experimentally. When the temperature rise of metal surfaces by IPIB irradiation exceeds their boiling point, it is found that machining roughness on surfaces is removed. The experiments were performed with the pulsed power generator HARIMA-II at Himeji Institute of Technology. The main components of the ion beam were carbon and fluorine ions. The IPIB was irradiated to metal plates (Al, Cu and Ti) which were placed at the focal point. Machining roughness on Ti surface was removed after IPIB irradiation, while roughness on Al and Cu plates was not removed. Using the present experimental parameters (beam power density: 32 W/cm 2 , pulse width: 25 ns), the temperature rise of the Ti surface was estimated to be 8,100 K which exceed its boiling point (3,000 K). However, the estimated temperatures of Al and Cu surfaces was 2,500 and 1,500 K, respectively, that are less than their boiling points. These studies above suggests that temperature rise over the boiling point of metals is necessary for removing machining roughness on metal surfaces

Intensity Correlation Analysis on Blue-Violet FemtosecondPulses from a Dispersion-Compensated GaInN Mode-LockedSemiconductor Laser Diode

Directory of Open Access Journals (Sweden)

Shunsuke Kono

2015-09-01

Full Text Available We investigated the spectral and temporal characteristics of blue-violetfemtosecond optical pulses generated by a passively mode-locked GaInN laser diode ina dispersion-compensated external cavity. The output optical pulses at 400 nm wereanalyzed in detail by intensity auto- and cross-correlation measurements using secondharmonic generation on the surface of a β-BaB2O4 crystal. The obtained results clarifiedwavelength-dependent chirp characteristics of the optical pulses. The analysis suggestedthat a large frequency shift due to saturation in the saturable absorber and gain sectionsplayed an important role in the generation of femtosecond optical pulses.

Intensity enhancement of cold neutrons from a coupled liquid-hydrogen moderator for pulsed cold neutron sources

International Nuclear Information System (INIS)

Ogawa, Y.; Kiyanagi, Y.; Kosugi, N.; Iwasa, H.; Furusaka, M.; Watanabe, N.

1999-01-01

In order to obtain higher cold neutron intensity from a coupled liquid-hydrogen moderator with a premoderator for pulsed cold neutron sources, we examined a partial enhancement method, namely, narrow beam extraction for both a flat liquid-hydrogen moderator and a single-groove one. Combined with the narrow beam extraction, which is especially suitable for small-angle scattering and neutron reflectometry experiments, a single-groove moderator provides higher intensity, by about 30%, than a flat-surface moderator at the region of interest on a viewed surface. The effect of double-side beam extraction from such moderators on the intensity gain factor is also discussed. (author)

Luminescence mechanism in doubly Gd, Nd-codoped fluoride crystals for VUV scintillators

Czech Academy of Sciences Publication Activity Database

Pejchal, Jan; Fukuda, K.; Babin, Vladimir; Kurosawa, S.; Yokota, Y.; Yoshikawa, A.; Nikl, Martin

2016-01-01

Roč. 169, Jan (2016), s. 682-689 ISSN 0022-2313. [International Conference on Luminescence and Optical Spectroscopy of Condensed Matter /17./. Wroclaw, 13.07.2014-18.07.2014] R&D Projects: GA MŠk(CZ) LH14266 Institutional support: RVO:68378271 Keywords : barium –lutetium–yttrium fluoride * lutetium fluoride * scintillator * VUV luminescence Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.686, year: 2016

Prospects of Using High-Intensity THz Pulses To Induce Ultrafast Temperature-Jumps in Liquid Water.

Science.gov (United States)

Mishra, Pankaj Kr; Bettaque, Vincent; Vendrell, Oriol; Santra, Robin; Welsch, Ralph

2018-06-01

Ultrashort, high-intensity terahertz (THz) pulses, e.g., generated at free-electron laser facilities, allow for direct investigation as well as the driving of intermolecular modes in liquids like water and thus will deepen our understanding of the hydrogen bonding network. In this work, the temperature-jump (T-jump) of water induced by THz radiation is simulated for ten different THz frequencies in the range from 3 to 30 THz and five different pulse intensities in the range from 1 × 10 11 to 5 × 10 12 W/cm 2 employing both ab initio molecular dynamics (AIMD) and force field molecular dynamics (FFMD) approaches. The most efficient T-jump can be achieved with 16 THz pulses. Three distinct T-jump mechanisms can be uncovered. For all cases, the T-jump mechanism proceeds within tens of femtoseconds (fs). For frequencies between 10 and 25 THz, most of the energy is initially transferred to the rotational degrees of freedom. Subsequently, the energy is redistributed to the translational and intramolecular vibrational degrees of freedom within a maximum of 500 fs. For the lowest frequencies considered (7 THz and below), translational and rotational degrees of freedom are heated within tens of fs as the THz pulse also couples to the intermolecular vibrations. Subsequently, the intramolecular vibrational modes are heated within a few hundred fs. At the highest frequencies considered (25 THz and above), vibrational and rotational degrees of freedom are heated within tens of fs, and energy redistribution to the translational degrees of freedom happens within several hundred fs. Both AIMD and FFMD simulations show a similar dependence of the T-jump on the frequency employed. However, the FFMD simulations overestimate the total energy transfer around the main peak and drop off too fast toward frequencies higher and lower than the main peak. These differences can be rationalized by missing elements, such as the polarizability, in the TIP4P/2005f force field employed. The

Evaluation of bipolar pulse generator for high-purity pulsed ion beam

International Nuclear Information System (INIS)

Ito, H.; Kitamura, I.; Masugata, K.

2008-01-01

A new type of pulsed ion beam accelerator named 'bipolar pulse accelerator (BPA)' has been proposed in order to improve the purity of intense pulsed ion beams. To confirm the principle of the BPA, we developed a bipolar pulse generator, which consists of a Marx generator and a pulse forming line (PFL) with a rail gap switch on its end. In this article, we report the experimental results of the bipolar pulse and evaluate the electrical characteristics of the bipolar pulse generator. When the bipolar pulse generator was operated at 70% of the full charge condition of the PEL, the bipolar pulse with the first (-138 kV, 72 ns) and the second pulse (+130 kV, 70 ns) was successfully obtained. The evaluation of the electrical characteristics indicates that the developed generator can produce the bipolar pulse with fast rise time and sharp reversing time. At present the bipolar pulse generator is installed in the B y type magnetically insulated ion diode and we carry out the experiment on the production of an intense pulsed ion beam by the bipolar pulse accelerator. (author)

Intense relativistic electron beam generation from KALI-5000 pulse accelerator

International Nuclear Information System (INIS)

Roy, A.; Mondal, J.; Mitra, S.; Durga Praveen Kumar, D.; Sharma, Archana; Nagesh, K.V.; Chakravarthy, D.P.

2006-01-01

Intense Relativistic Electron Beam (IREB) with parameters 420 keV, 22 kA, 100 ns has been generated from indigenously developed pulse power system KALI- 5000. High current electron beam is generated from explosive field emission graphite cathodes. Studies have been conducted by changing the diameter of graphite cathode and also the anode cathode gap. In order to avoid prepulse effect it was concluded that anode cathode (AK) gap should be kept larger than estimated by the Child Langmuir relation. Beam voltage has been measured by a copper sulphate voltage divider, beam current by a self integrating Rogowski coil and B-dot probe. Electron beam diode Impedance and Perveance were obtained from the experimentally measured beam voltage and current. (author)

FORMATION OF S-BEARING SPECIES BY VUV/EUV IRRADIATION OF H2S-CONTAINING ICE MIXTURES: PHOTON ENERGY AND CARBON SOURCE EFFECTS

International Nuclear Information System (INIS)

Chen, Y.-J.; Juang, K.-J.; Qiu, J.-M.; Chu, C.-C.; Yih, T.-S.; Nuevo, M.; Jiménez-Escobar, A.; Muñoz Caro, G. M.; Wu, C.-Y. R.; Fung, H.-S.; Ip, W.-H.

2015-01-01

Carbonyl sulfide (OCS) is a key molecule in astrobiology that acts as a catalyst in peptide synthesis by coupling amino acids. Experimental studies suggest that hydrogen sulfide (H 2 S), a precursor of OCS, could be present in astrophysical environments. In the present study, we used a microwave-discharge hydrogen-flow lamp, simulating the interstellar UV field, and a monochromatic synchrotron light beam to irradiate CO:H 2 S and CO 2 :H 2 S ice mixtures at 14 K with vacuum ultraviolet (VUV) or extreme ultraviolet (EUV) photons in order to study the effect of the photon energy and carbon source on the formation mechanisms and production yields of S-containing products (CS 2 , OCS, SO 2 , etc.). Results show that (1) the photo-induced OCS production efficiency in CO:H 2 S ice mixtures is higher than that of CO 2 :H 2 S ice mixtures; (2) a lower concentration of H 2 S enhances the production efficiency of OCS in both ice mixtures; and (3) the formation pathways of CS 2 differ significantly upon VUV and EUV irradiations. Furthermore, CS 2 was produced only after VUV photoprocessing of CO:H 2 S ices, while the VUV-induced production of SO 2 occurred only in CO 2 :H 2 S ice mixtures. More generally, the production yields of OCS, H 2 S 2 , and CS 2 were studied as a function of the irradiation photon energy. Heavy S-bearing compounds were also observed using mass spectrometry during the warm-up of VUV/EUV-irradiated CO:H 2 S ice mixtures. The presence of S-polymers in dust grains may account for the missing sulfur in dense clouds and circumstellar environments

VUV Study of Electron-Pyrimidine Dissociative Excitation

Science.gov (United States)

Hein, Jeff; Al-Khazraji, Hajar; Tiessen, Collin; Lukic, Dragan; Trocchi, Joshuah; McConkey, William

2013-05-01

A crossed electron-gas beam system coupled to a VUV spectrometer has been used to investigate the dissociation of pyrimidine (C4H4N2) into excited atomic fragments in the electron-impact energy range from threshold to 375 eV. Data have been made absolute using Lyman- α from H2 as a secondary standard. The main features in the spectrum are the H Lyman series lines. The emission cross section of Lyman- α is measured to be (2.44 +/- 0.25) 10-18 cm2 at 100 eV impact energy. The probability of extracting C or N atoms from the ring is shown to be very small. Possible dissociation channels and excitation mechanisms in the parent molecule will be discussed. The authors thank NSERC (Canada) for financial support.

VUV Spectroscopy of the Sun as a Star

Science.gov (United States)

Kankelborg, Charles; Philip, Judge; Winebarger, Amy R.; Kobayashi, Ken; Smart, Roy

2017-08-01

We describe a new sounding rocket mission to obtain the first high resolution, high quality VUV (100-200 nm) spectrum of the Sun-as-a-star. Our immediate science goal is to understand better the processes of chromospheric and coronal heating. HST data exist for a dozen or so Sun-like stars of a quality already beyond our ability to construct a comparable sun-as-a-star UV spectrum. The solar spectrum we obtain will enable us to understand the nature of magnetic energy dissipation as a Sun-like star evolves, and the dependence of magnetic activity on stellar mass and metallicity. This poster presents the instrument design, scientific prospects, and broader impacts of the proposed mission.

Propagation of an intense laser pulse in an under-dense plasma: channeling and stimulated Raman scattering

International Nuclear Information System (INIS)

Friou, A.

2012-01-01

This thesis is divided in two parts: i) the laser channeling in hundreds of microns long under-dense plasmas (0.1 nc ≤ n ≤ nc, nc being the critical density) of a laser pulse of intensity 10 18-20 W/cm 2 and duration 1-10 ps; ii) the saturation mechanisms of stimulated Raman back-scattering of a laser pulse of intensity 10 14 to 10 16 W/cm 2 and duration of about 1 ps. A parametric study was performed to study the channeling of a very intense laser pulse, using a 2D PIC (Particle In Cell) code. Various kinds of channels were obtained depending on the laser and plasma parameters, thereby reproducing and enlarging previous studies. Moreover, the channeling velocity was measured and scaling laws were established for homogeneous plasmas. They are then applied to inhomogeneous plasmas, similar to those encountered in inertial confinement fusion (ICF). It is then possible to estimate the energy necessary to channel to the critical density, an important step for the fast ignition scheme of ICF. Raman saturation was studied using numerical simulations, in order to determine if it is due to dephasing or to the growth of sidebands, using different approaches. The first is to study Raman simulations (electromagnetic) performed with kinetic PIC and Vlasov codes. The second, is to study the evolution of a plasma initialized with a distribution function after the adiabatic theory, using a Vlasov code (electrostatic). In this case, we observe the growth of a sideband, with dominant wave number and growth rate in good agreement with kinetic simulations. The saturation of the plasma wave can be caused by both saturation mechanisms. [fr

Dependence of core heating properties on heating pulse duration and intensity

Science.gov (United States)

Johzaki, Tomoyuki; Nagatomo, Hideo; Sunahara, Atsushi; Cai, Hongbo; Sakagami, Hitoshi; Mima, Kunioki

2009-11-01

In the cone-guiding fast ignition, an imploded core is heated by the energy transport of fast electrons generated by the ultra-intense short-pulse laser at the cone inner surface. The fast core heating (˜800eV) has been demonstrated at integrated experiments with GEKKO-XII+ PW laser systems. As the next step, experiments using more powerful heating laser, FIREX, have been started at ILE, Osaka university. In FIREX-I (phase-I of FIREX), our goal is the demonstration of efficient core heating (Ti ˜ 5keV) using a newly developed 10kJ LFEX laser. In the first integrated experiments, the LFEX laser is operated with low energy mode (˜0.5kJ/4ps) to validate the previous GEKKO+PW experiments. Between the two experiments, though the laser energy is similar (˜0.5kJ), the duration is different; ˜0.5ps in the PW laser and ˜ 4ps in the LFEX laser. In this paper, we evaluate the dependence of core heating properties on the heating pulse duration on the basis of integrated simulations with FI^3 (Fast Ignition Integrated Interconnecting) code system.

Degradation mechanisms of the blue-emitting phosphor BaMgAl{sub 10}O{sub 17}:Eu{sup 2+} under baking and VUV-irradiating treatments

Energy Technology Data Exchange (ETDEWEB)

Zhang Shuxiu E-mail: shuxiu_zhang@dyden.co.jp; Kono, Toshihiko; Ito, Akira; Yasaka, Taketo; Uchiike, Heiju

2004-01-01

The luminescent properties of an Eu{sup 2+}-activated hexagonal aluminate, BaMgAl{sub 10}O{sub 17} (BAM), were studied under 147- and 254-nm excitations. The BAM samples were thermally treated by baking and then irradiated in vacuum ultraviolet (VUV) rays. The results show that the emission efficiency of Eu{sup 2+} in BAM under 147-nm excitation degraded seriously after baking or VUV-irradiating treatments, while no significant degradation was observed under 254-nm excitation. The degree of degradation depended on the excitation wavelength, and the absorption edge of the BAM host was suggested to be close to 175 nm (7.2 eV). The differences between the thermal-induced and the VUV-irradiation-induced degradations, and their mechanisms are discussed for the color plasma display applications.

Photoluminescence of Eu2+-doped CaMgSi2xO6+2x (1.00≤x≤1.20) phosphors in UV-VUV region

International Nuclear Information System (INIS)

Zhang Zhiya; Wang Yuhua

2008-01-01

Alkaline-earth silicate phosphors CaMgSi 2x O 6+2x :Eu 2+ (1.00≤x≤1.20) were prepared by traditional solid-state reaction. The phosphors showed an intense blue emission centered around 453 nm, with both 254 and 147 nm excitations. The host absorption below 200 nm in the excitation spectra consisted of two bands around 160 and 190 nm. The band around 160 nm was ascertained to be associated with the SiO 4 -tetrahedra and MgO 6 -polyhedra, and that around 190 nm was due to the CaO 8 -polyhedra or some impurities. The incorporation of excess Si of less than 15% would not lead to formation of impurities and the results indicated that an appropriate Si excess could improve the Photoluminescence (PL) intensity in both ultraviolet (UV) and vacuum ultraviolet (VUV) regions

Carcinogenesis related to intense pulsed light and UV exposure

DEFF Research Database (Denmark)

Hedelund, L; Lerche, C; Wulf, H C

2006-01-01

This study examines whether intense pulsed light (IPL) treatment has a carcinogenic potential itself or may influence ultraviolet (UV)-induced carcinogenesis. Secondly, it evaluates whether UV exposure may influence IPL-induced side effects. Hairless, lightly pigmented mice (n=144) received three...... observation period. Side effects were evaluated clinically. No tumors appeared in untreated control mice or in just IPL-treated mice. Skin tumors developed in UV-exposed mice independently of IPL treatments. The time it took for 50% of the mice to first develop skin tumor ranged from 47 to 49 weeks...... in preoperative UV-exposed mice (p=0.94) and from 22 to 23 weeks in pre- and postoperative UV-exposed mice (p=0.11). IPL rejuvenation of lightly pigmented skin did not induce pigmentary changes (p=1.00). IPL rejuvenation of UV-pigmented skin resulted in an immediate increased skin pigmentation and a subsequent...

Experimental study of pyrolytic boron nitride at high temperature with and without proton and VUV irradiations

International Nuclear Information System (INIS)

Balat-Pichelin, M.; Eck, J.; Heurtault, S.; Glénat, H.

2014-01-01

Highlights: • New results for the high temperature study of pBN in high vacuum for the heat shield of solar probes. • Physico-chemical behavior of pBN studied up to 1700 K with proton and VUV irradiations. • Rather low effect of synergistic aggressions on the microstructure of pBN material. • The α/ε ratio of pBN coating on C/C measured up to 2200 K is 20% lower than for the C/C itself. - Abstract: In the frame of future exploration missions such as Solar Probe Plus (NASA) and PHOIBOS (ESA), research was carried out to study pyrolytic BN material envisaged as coating for their heat shields. The physico-chemical behavior of CVD pBN at very high temperature with or without hydrogen ions and VUV (Vacuum Ultra-Violet) irradiations was studied in high vacuum together with the in situ measurement of the thermal radiative properties conditioning the thermal equilibrium of the heat shield. Experimental results obtained on massive pBN samples are presented through in situ mass spectrometry and mass loss rate, and post-test microstructural characterization by XRD, SEM, AFM and nano-indentation techniques, some of them leading to mechanical properties. It could be concluded that synergistic effect of high temperature, protons and VUV radiation has an impact on the emission of gaseous species, the mass loss rate and the mechanical properties of the material

Intense picosecond pulsed electric fields induce apoptosis through a mitochondrial-mediated pathway in HeLa cells

Science.gov (United States)

HUA, YUAN-YUAN; WANG, XIAO-SHU; ZHANG, YU; YAO, CHEN-GUO; ZHANG, XI-MING; XIONG, ZHENG-AI

2012-01-01

The application of pulsed electric fields (PEF) is emerging as a new technique for tumor therapy. Picosecond pulsed electric fields (psPEF) can be transferred to target deep tissue non-invasively and precisely, but the research of the biological effects of psPEF on cells is limited. Electric theory predicts that intense psPEF will target mitochondria and lead to changes in transmembrane potential, therefore, it is hypothesized that it can induce mitochondrial-mediated apoptosis. HeLa cells were exposed to psPEF in this study to investigate this hypothesis. MTT assay demonstrated that intense psPEF significantly inhibited the proliferation of HeLa cells in a dose-dependent manner. Typical characteristics of apoptosis in HeLa cells were observed, using transmission electron microscopy. Loss of mitochondrial transmembrane potential was explored using laser scanning confocal microscopy with Rhodamine-123 (Rh123) staining. Furthermore, the mitochondrial apoptotic events were also confirmed by western blot analysis for the release of cytochrome C and apoptosis-inducing factor from mitochondria into the cytosol. In addition, activation of caspase-3, caspase-9, upregulation of Bax, p53 and downregulation of Bcl-2 were observed in HeLa cells also indicating apoptosis. Taken together, these results demonstrate that intense psPEF induce cell apoptosis through a mitochondrial-mediated pathway. PMID:22307872

The deposition of thin metal films at the high-intensity pulsed-ion-beam influence on the metals

International Nuclear Information System (INIS)

Remnev, G.E.; Zakoutaev, A.N.; Grushin, I.I.; Matvenko, V.M.; Potemkin, A.V.; Ryzhkov, V.A.; Chernikov, E.V.

1996-01-01

A high-intensity pulsed ion beam with parameters: ion energy 350-500 keV, ion current density at a target > 200 A/cm 2 , pulse duration 60 ns, was used for metal deposition. The film deposition rate was 0.6-4.0 mm/s. Transmission electron microscopy/transmission electron diffraction investigations of the copper target-film system were performed. The impurity content in the film was determined by x-ray fluorescence analysis and secondary ion mass spectrometry. The angular distributions of the ablated plasma were measured. (author). 2 figs., 7 refs

The deposition of thin metal films at the high-intensity pulsed-ion-beam influence on the metals

Energy Technology Data Exchange (ETDEWEB)

Remnev, G E; Zakoutaev, A N; Grushin, I I; Matvenko, V M; Potemkin, A V; Ryzhkov, V A [Tomsk Polytechnic Univ. (Russian Federation). Nuclear Physics Inst.; Ivanov, Yu F [Construction Academy, Tomsk (Russian Federation); Chernikov, E V [Siberian Physical Technical Institute, Tomsk (Russian Federation)

1997-12-31

A high-intensity pulsed ion beam with parameters: ion energy 350-500 keV, ion current density at a target > 200 A/cm{sup 2}, pulse duration 60 ns, was used for metal deposition. The film deposition rate was 0.6-4.0 mm/s. Transmission electron microscopy/transmission electron diffraction investigations of the copper target-film system were performed. The impurity content in the film was determined by x-ray fluorescence analysis and secondary ion mass spectrometry. The angular distributions of the ablated plasma were measured. (author). 2 figs., 7 refs.

Comparative Study Between Intense Pulsed Light IPLAND Pulsed Dye Laser In The Treatment Of Striae Distensae

International Nuclear Information System (INIS)

El-Khalafawy, Gh.M.K.A.

2013-01-01

Pulsed dye laser (PDL) and Intense Pulsed Light (IPL) have been used to treat Striae Distensae (SD). Thirty patients with age ranging from 14 - 42 years were included in this study. Twenty patients were treated on one side of their bodies with PDL and on the other side with IPL while seven patients were treated on both sides by IPL and three patients were treated on both sides by PDL for five sessions with four weeks interval between sessions. Skin biopsies were stained with H and E, Masson Trichrome, Orcein, Alcian blue and anti-collagen I Α1. After both PDL and IPL treatments striae width was decreased and the texture was improved in a highly significant manners where P value was 0.001. Collagen expression was increased in a highly significant manner and P values were <0.001 and 0.004 after PDL and IPL treatments respectively. However, PDL induced expression of collagen I in a highly significant manner compared to the treatment with IPL where P values were <0.001 and 0.193 respectively. Striae rubra gave a superior response with either PDL or IPL compared to striae alba which was evaluated clinically by the width, color and texture, although the histological changes could not verify this consequence. Both PDL and IPL can enhance the clinical picture of striae through collagen stimulation therapeutic modalities

Irradiation of cells by single and double pulses of high intensity radiation: oxygen sensitization and diffusion kinetics

International Nuclear Information System (INIS)

Epp, E.R.; Ling, C.C.; Weiss, H.

1976-01-01

This paper discusses advances made on both experimental and theoretical approaches involving single and double pulses of high intensity ionizing radiation delivered to cultured bacterial and mammalian cells where the effect of oxygen is concerned. Information gained on the lifetime of oxygen-sensitive species suspected to be produced in critical molecules in irradiated cells and perhaps intimately related to the still unknown mechanisms of oxygen sensitization is described. The diffusion characteristics of oxygen at the cellular level obtained from experimental data are discussed. Current knowledge on intracellular radiolytic oxygen depletion is also presented. Future work on the use of high intensity pulsed radiation as a tool in cellular radiobiological research is outlined. It is expected that obtaining knowledge of the time available for damaged molecules to enter into chemical reactions may lead to insights into the mechanisms of radiation injury in cells, such as those involved in the oxygen effect. (Auth.)

Laser ablation comparison by picosecond pulses train and nanosecond pulse

Science.gov (United States)

Lednev, V. N.; Filippov, M. N.; Bunkin, A. F.; Pershin, S. M.

2015-12-01

A comparison of laser ablation by a train of picosecond pulses and nanosecond pulses revealed a difference in laser craters, ablation thresholds, plasma sizes and spectral line intensities. Laser ablation with a train of picosecond pulses resulted in improved crater quality while ablated mass decreased up to 30%. A reduction in laser plasma dimensions for picosecond train ablation was observed while the intensity of atomic/ionic lines in the plasma spectra was greater by a factor of 2-4 indicating an improved excitation and atomization in the plasma.

vuv fluorescence from selective high-order multiphoton excitation of N2

International Nuclear Information System (INIS)

Coffee, Ryan N.; Gibson, George N.

2004-01-01

Recent fluorescence studies suggest that ultrashort pulse laser excitation may be highly selective. Selective high-intensity laser excitation holds important consequences for the physics of multiphoton processes. To establish the extent of this selectivity, we performed a detailed comparative study of the vacuum ultraviolet fluorescence resulting from the interaction of N 2 and Ar with high-intensity infrared ultrashort laser pulses. Both N 2 and Ar reveal two classes of transitions, inner-valence ns ' l ' . From their pressure dependence, we associate each transition with either plasma or direct laser excitation. Furthermore, we qualitatively confirm such associations with the time dependence of the fluorescence signal. Remarkably, only N 2 presents evidence of direct laser excitation. This direct excitation produces ionic nitrogen fragments with inner-valence (2s) holes, two unidentified transitions, and one molecular transition, the N 2 + :X 2 Σ g + 2 Σ u + . We discuss these results in the light of a recently proposed model for multiphoton excitation

Wave Intensity Analysis of Right Ventricular Function during Pulsed Operation of Rotary Left Ventricular Assist Devices.

Science.gov (United States)

Bouwmeester, J Christopher; Park, Jiheum; Valdovinos, John; Bonde, Pramod

2018-05-29

Changing the speed of left ventricular assist devices (LVADs) cyclically may be useful to restore aortic pulsatility; however, the effects of this pulsation on right ventricular (RV) function are unknown. This study investigates the effects of direct ventricular interaction by quantifying the amount of wave energy created by RV contraction when axial and centrifugal LVADs are used to assist the left ventricle. In 4 anesthetized pigs, pressure and flow were measured in the main pulmonary artery and wave intensity analysis was used to identify and quantify the energy of waves created by the RV. The axial pump depressed the intensity of waves created by RV contraction compared with the centrifugal pump. In both pump designs, there were only minor and variable differences between the continuous and pulsed operation on RV function. The axial pump causes the RV to contract with less energy compared with a centrifugal design. Diminishing the ability of the RV to produce less energy translates to less pressure and flow produced, which may lead to LVAD-induced RV failure. The effects of pulsed LVAD operation on the RV appear to be minimal during acute observation of healthy hearts. Further study is necessary to uncover the effects of other modes of speed modulation with healthy and unhealthy hearts to determine if pulsed operation will benefit patients by reducing LVAD complications.

High-power, photofission-inducing bremsstrahlung source for intense pulsed active detection of fissile material

Directory of Open Access Journals (Sweden)

J. C. Zier

2014-06-01

Full Text Available Intense pulsed active detection (IPAD is a promising technique for detecting fissile material to prevent the proliferation of special nuclear materials. With IPAD, fissions are induced in a brief, intense radiation burst and the resulting gamma ray or neutron signals are acquired during a short period of elevated signal-to-noise ratio. The 8 MV, 200 kA Mercury pulsed-power generator at the Naval Research Laboratory coupled to a high-power vacuum diode produces an intense 30 ns bremsstrahlung beam to study this approach. The work presented here reports on Mercury experiments designed to maximize the photofission yield in a depleted-uranium (DU object in the bremsstrahlung far field by varying the anode-cathode (AK diode gap spacing and by adding an inner-diameter-reducing insert in the outer conductor wall. An extensive suite of diagnostics was fielded to measure the bremsstrahlung beam and DU fission yield as functions of diode geometry. Delayed fission neutrons from the DU proved to be a valuable diagnostic for measuring bremsstrahlung photons above 5 MeV. The measurements are in broad agreement with particle-in-cell and Monte Carlo simulations of electron dynamics and radiation transport. These show that with increasing AK gap, electron losses to the insert and outer conductor wall increase and that the electron angles impacting the bremsstrahlung converter approach normal incidence. The diode conditions for maximum fission yield occur when the gap is large enough to produce electron angles close to normal, yet small enough to limit electron losses.

High-power, photofission-inducing bremsstrahlung source for intense pulsed active detection of fissile material

Science.gov (United States)

Zier, J. C.; Mosher, D.; Allen, R. J.; Commisso, R. J.; Cooperstein, G.; Hinshelwood, D. D.; Jackson, S. L.; Murphy, D. P.; Ottinger, P. F.; Richardson, A. S.; Schumer, J. W.; Swanekamp, S. B.; Weber, B. V.

2014-06-01

Intense pulsed active detection (IPAD) is a promising technique for detecting fissile material to prevent the proliferation of special nuclear materials. With IPAD, fissions are induced in a brief, intense radiation burst and the resulting gamma ray or neutron signals are acquired during a short period of elevated signal-to-noise ratio. The 8 MV, 200 kA Mercury pulsed-power generator at the Naval Research Laboratory coupled to a high-power vacuum diode produces an intense 30 ns bremsstrahlung beam to study this approach. The work presented here reports on Mercury experiments designed to maximize the photofission yield in a depleted-uranium (DU) object in the bremsstrahlung far field by varying the anode-cathode (AK) diode gap spacing and by adding an inner-diameter-reducing insert in the outer conductor wall. An extensive suite of diagnostics was fielded to measure the bremsstrahlung beam and DU fission yield as functions of diode geometry. Delayed fission neutrons from the DU proved to be a valuable diagnostic for measuring bremsstrahlung photons above 5 MeV. The measurements are in broad agreement with particle-in-cell and Monte Carlo simulations of electron dynamics and radiation transport. These show that with increasing AK gap, electron losses to the insert and outer conductor wall increase and that the electron angles impacting the bremsstrahlung converter approach normal incidence. The diode conditions for maximum fission yield occur when the gap is large enough to produce electron angles close to normal, yet small enough to limit electron losses.

No midterm benefit from low intensity pulsed ultrasound after chevron osteotomy for hallux valgus.

Science.gov (United States)

Zacherl, Max; Gruber, Gerald; Radl, Roman; Rehak, Peter H; Windhager, Reinhard

2009-08-01

Chevron osteotomy is a widely accepted method for correction of symptomatic hallux valgus deformity. Full weight bearing in regular shoes is not recommended before 6 weeks after surgery. Low intensity pulsed ultrasound is known to stimulate bone formation leading to more stable callus and faster bony fusion. We performed a randomized, placebo-controlled, double-blinded study on 44 participants (52 feet) who underwent chevron osteotomy to evaluate the influence of daily transcutaneous low intensity pulsed ultrasound (LIPUS) treatment at the site of osteotomy. Follow-up at 6 weeks and 1 year included plain dorsoplantar radiographs, hallux-metatarsophalangeal-interphalangeal scale and a questionnaire on patient satisfaction. There was no statistical difference in any pre- or postoperative clinical features, patient satisfaction or radiographic measurements (hallux valgus angle, intermetatarsal angle, sesamoid index and metatarsal index) except for the first distal metatarsal articular angle (DMAA). The DMAA showed statistically significant (p = 0.046) relapse in the placebo group upon comparison of intraoperative radiographs after correction and fixation (5.2 degrees) and at the 6-week follow-up (10.6 degrees). Despite potential impact of LIPUS on bone formation, we found no evidence of an influence on outcome 6 weeks and 1 year after chevron osteotomy for correction of hallux valgus deformity.

FORMATION OF S-BEARING SPECIES BY VUV/EUV IRRADIATION OF H{sub 2}S-CONTAINING ICE MIXTURES: PHOTON ENERGY AND CARBON SOURCE EFFECTS

Energy Technology Data Exchange (ETDEWEB)

Chen, Y.-J.; Juang, K.-J.; Qiu, J.-M.; Chu, C.-C.; Yih, T.-S. [Department of Physics, National Central University, Jhongli City, Taoyuan County 32054, Taiwan (China); Nuevo, M. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Jiménez-Escobar, A.; Muñoz Caro, G. M. [Centro de Astrobiología, INTA-CSIC, Torrejón de Ardoz, E-28850 Madrid (Spain); Wu, C.-Y. R. [Space Sciences Center and Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-1341 (United States); Fung, H.-S. [National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China); Ip, W.-H. [Graduate Institute of Astronomy, National Central University, Jhongli City, Taoyuan County 32049, Taiwan (China)

2015-01-10

Carbonyl sulfide (OCS) is a key molecule in astrobiology that acts as a catalyst in peptide synthesis by coupling amino acids. Experimental studies suggest that hydrogen sulfide (H{sub 2}S), a precursor of OCS, could be present in astrophysical environments. In the present study, we used a microwave-discharge hydrogen-flow lamp, simulating the interstellar UV field, and a monochromatic synchrotron light beam to irradiate CO:H{sub 2}S and CO{sub 2}:H{sub 2}S ice mixtures at 14 K with vacuum ultraviolet (VUV) or extreme ultraviolet (EUV) photons in order to study the effect of the photon energy and carbon source on the formation mechanisms and production yields of S-containing products (CS{sub 2}, OCS, SO{sub 2}, etc.). Results show that (1) the photo-induced OCS production efficiency in CO:H{sub 2}S ice mixtures is higher than that of CO{sub 2}:H{sub 2}S ice mixtures; (2) a lower concentration of H{sub 2}S enhances the production efficiency of OCS in both ice mixtures; and (3) the formation pathways of CS{sub 2} differ significantly upon VUV and EUV irradiations. Furthermore, CS{sub 2} was produced only after VUV photoprocessing of CO:H{sub 2}S ices, while the VUV-induced production of SO{sub 2} occurred only in CO{sub 2}:H{sub 2}S ice mixtures. More generally, the production yields of OCS, H{sub 2}S{sub 2}, and CS{sub 2} were studied as a function of the irradiation photon energy. Heavy S-bearing compounds were also observed using mass spectrometry during the warm-up of VUV/EUV-irradiated CO:H{sub 2}S ice mixtures. The presence of S-polymers in dust grains may account for the missing sulfur in dense clouds and circumstellar environments.

Surface modification of LiNbO3 and KTa1-xNbxO3 crystals irradiated by intense pulsed ion beam

Science.gov (United States)

Cui, Xiaojun; Shen, Jie; Zhong, Haowen; Zhang, Jie; Yu, Xiao; Liang, Guoying; Qu, Miao; Yan, Sha; Zhang, Xiaofu; Le, Xiaoyun

2017-10-01

In this work, we studied the surface modification of LiNbO3 and KTa1-xNbxO3 irradiated by intense pulsed ion beam, which was mainly composed of H+ (70%) and Cn+ (30%) at an acceleration voltage of about 450 kV. The surface morphologies, microstructural evolution and elemental analysis of the sample surfaces after IPIB irradiation have been analyzed by scanning electron microscope, atomic force microscope, X-ray diffraction and energy dispersive spectrometer techniques, respectively. The results show that the surface morphologies have significant difference impacted by the irradiation effect. Regular gully damages range from 200 to 400 nm in depth appeared in LiNbO3 under 2 J/cm2 energy density for 1 pulse, block cracking appeared in KTa1-xNbxO3 at the same condition. Surface of the crystals have melted and were darkened with the increasing number up to 5 pulses. Crystal lattice arrangement is believed to be the dominant reason for the different experimental results irradiated by intense pulsed ion beam.

Advanced numerical studies of the neutralized drift compression of intense ion beam pulses

Directory of Open Access Journals (Sweden)

Adam B. Sefkow

2007-10-01

Full Text Available Longitudinal bunch compression of intense ion beams for warm dense matter and heavy ion fusion applications occurs by imposing an axial velocity tilt onto an ion beam across the acceleration gap of a linear induction accelerator, and subsequently allowing the beam to drift through plasma in order to neutralize its space-charge and current as the pulse compresses. The detailed physics and implications of acceleration gap effects and focusing aberration on optimum longitudinal compression are quantitatively reviewed using particle-in-cell simulations, showing their dependence on many system parameters. Finite-size gap effects are shown to result in compression reduction, due to an increase in the effective longitudinal temperature imparted to the beam, and a decrease in intended fractional tilt. Sensitivity of the focal plane quality to initial longitudinal beam temperature is explored, where slower particles are shown to experience increased levels of focusing aberration compared to faster particles. A plateau effect in axial compression is shown to occur for larger initial pulse lengths, where the increases in focusing aberration over the longer drift lengths involved dominate the increases in relative compression, indicating a trade-off between current compression and pulse duration. The dependence on intended fractional tilt is also discussed and agrees well with theory. A balance between longer initial pulse lengths and larger tilts is suggested, since both increase the current compression, but have opposite effects on the final pulse length, drift length, and amount of longitudinal focusing aberration. Quantitative examples are outlined that explore the sensitive dependence of compression on the initial kinetic energy and thermal distribution of the beam particles. Simultaneous transverse and longitudinal current density compression can be achieved in the laboratory using a strong final-focus solenoid, and simulations addressing the effects

A new instrument of VUV laser desorption/ionization mass spectrometry imaging with micrometer spatial resolution and low level of molecular fragmentation.

Science.gov (United States)

Wang, Jia; Liu, Feng; Mo, Yuxiang; Wang, Zhaoying; Zhang, Sichun; Zhang, Xinrong

2017-11-01

Mass spectrometry imaging (MSI) has important applications in material research, biology, and medicine. The MSI method based on UV laser desorption/ionization (UVLDI) can obtain images of intact samples, but has a high level of molecular fragmentation. In this work, we report a new MSI instrument that uses a VUV laser (125.3 nm) as a desorption/ionization source to exploit its advantages of high single photon energy and small focus size. The new instrument was tested by the mass spectra of Nile red and FGB (Fibrinogen beta chain) samples and mass spectrometric images of a fly brain section. For the tested samples, the VUVDI method offers lower levels of molecular fragmentations and higher sensitivities than those of the UVLDI method and second ion mass spectrometry imaging method using a Bi 3 + beam. The ablation crater produced by the focused VUV laser on a quartz plate has an area of 10 μm 2 . The VUV laser is prepared based on the four-wave mixing method using three collimated laser beams and a heated Hg cell.

A new instrument of VUV laser desorption/ionization mass spectrometry imaging with micrometer spatial resolution and low level of molecular fragmentation

Science.gov (United States)

Wang, Jia; Liu, Feng; Mo, Yuxiang; Wang, Zhaoying; Zhang, Sichun; Zhang, Xinrong

2017-11-01

Mass spectrometry imaging (MSI) has important applications in material research, biology, and medicine. The MSI method based on UV laser desorption/ionization (UVLDI) can obtain images of intact samples, but has a high level of molecular fragmentation. In this work, we report a new MSI instrument that uses a VUV laser (125.3 nm) as a desorption/ionization source to exploit its advantages of high single photon energy and small focus size. The new instrument was tested by the mass spectra of Nile red and FGB (Fibrinogen beta chain) samples and mass spectrometric images of a fly brain section. For the tested samples, the VUVDI method offers lower levels of molecular fragmentations and higher sensitivities than those of the UVLDI method and second ion mass spectrometry imaging method using a Bi3+ beam. The ablation crater produced by the focused VUV laser on a quartz plate has an area of 10 μm2. The VUV laser is prepared based on the four-wave mixing method using three collimated laser beams and a heated Hg cell.

VUV photoionization and dissociative photoionization of the prebiotic molecule acetyl cyanide: Theory and experiment

International Nuclear Information System (INIS)

Bellili, A.; Hochlaf, M.; Schwell, M.; Bénilan, Y.; Fray, N.; Gazeau, M.-C.; Mogren Al-Mogren, M.; Guillemin, J.-C.; Poisson, L.

2014-01-01

The present combined theoretical and experimental investigation concerns the single photoionization of gas-phase acetyl cyanide and the fragmentation pathways of the resulting cation. Acetyl cyanide (AC) is inspired from both the chemistry of cyanoacetylene and the Strecker reaction which are thought to be at the origin of medium sized prebiotic molecules in the interstellar medium. AC can be formed by reaction from cyanoacetylene and water but also from acetaldehyde and HCN or the corresponding radicals. In view of the interpretation of vacuum ultraviolet (VUV) experimental data obtained using synchrotron radiation, we explored the ground potential energy surface (PES) of acetyl cyanide and of its cation using standard and recently implemented explicitly correlated methodologies. Our PES covers the regions of tautomerism (between keto and enol forms) and of the lowest fragmentation channels. This allowed us to deduce accurate thermochemical data for this astrobiologically relevant molecule. Unimolecular decomposition of the AC cation turns out to be very complex. The implications for the evolution of prebiotic molecules under VUV irradiation are discussed

VUV photoionization and dissociative photoionization of the prebiotic molecule acetyl cyanide: Theory and experiment

Energy Technology Data Exchange (ETDEWEB)

Bellili, A.; Hochlaf, M., E-mail: hochlaf@univ-mlv.fr, E-mail: martin.schwell@lisa.u-pec.fr [Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, Université Paris-Est, 5 bd Descartes, 77454 Marne-la-Vallée (France); Schwell, M., E-mail: hochlaf@univ-mlv.fr, E-mail: martin.schwell@lisa.u-pec.fr; Bénilan, Y.; Fray, N.; Gazeau, M.-C. [Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR 7583 CNRS, Institut Pierre et Simon Laplace, Universités Paris-Est Créteil et Paris Diderot, 61 Avenue du Général de Gaulle, 94010 Créteil (France); Mogren Al-Mogren, M. [Chemistry Department, Faculty of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Guillemin, J.-C. [Institut des Sciences Chimiques de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, Allée de Beaulieu, CS 50837, 35708 Rennes Cedex 7 (France); Poisson, L. [Laboratoire Francis Perrin, CNRS URA 2453, CEA, IRAMIS, Laboratoire Interactions Dynamique et Lasers, Bât 522, F-91191 Gif/Yvette (France)

2014-10-07

The present combined theoretical and experimental investigation concerns the single photoionization of gas-phase acetyl cyanide and the fragmentation pathways of the resulting cation. Acetyl cyanide (AC) is inspired from both the chemistry of cyanoacetylene and the Strecker reaction which are thought to be at the origin of medium sized prebiotic molecules in the interstellar medium. AC can be formed by reaction from cyanoacetylene and water but also from acetaldehyde and HCN or the corresponding radicals. In view of the interpretation of vacuum ultraviolet (VUV) experimental data obtained using synchrotron radiation, we explored the ground potential energy surface (PES) of acetyl cyanide and of its cation using standard and recently implemented explicitly correlated methodologies. Our PES covers the regions of tautomerism (between keto and enol forms) and of the lowest fragmentation channels. This allowed us to deduce accurate thermochemical data for this astrobiologically relevant molecule. Unimolecular decomposition of the AC cation turns out to be very complex. The implications for the evolution of prebiotic molecules under VUV irradiation are discussed.

Experience with a high-brightness storage ring: the NSLS 750 MeV vuv ring

International Nuclear Information System (INIS)

Galayda, J.

1984-01-01

The NSLS vuv ring is the first implementation of the proposals of R. Chasman and G.K. Green for a synchrotron radiation source with enhanced brightness: its lattice is a series of achromatic bends with two zero-gradient dipoles each, giving small damped emittance; and these bends are connected by straight sections with zero dispersion to accommodate wigglers and undulators without degrading the radiation damping properties of the ring. The virtues of the Chasman-Green lattice, its small betatron and synchrotron emittances, may be understood with some generality; e.g. the electron γm 0 c 2 energy and the number of achromatic bends M sets a lower limit on the betatron emittance of e/sub x/ > 7.7 x 10 -13 γ 2 /M meter-radians. There is strong interest in extrapolation of this type of lattice to 6 GeV and to 32 achromatic bends. The subject of this report is the progress toward achieving performance in the vuv ring limited by the radiation damping parameters optimized in its design. 14 refs., 4 figs., 1 tab

Optimized simultaneous transverse and longitudinal focusing of intense ion beam pulses for warm dense matter applications

International Nuclear Information System (INIS)

Sefkow, Adam B.; Davidson, Ronald C.; Kaganovich, Igor D.; Gilson, Erik P.; Roy, Prabir K.; Seidl, Peter A.; Yu, Simon S.; Welch, Dale R.; Rose, David V.; Barnard, John J.

2007-01-01

Intense, space-charge-dominated ion beam pulses for warm dense matter and heavy ion fusion applications must undergo simultaneous transverse and longitudinal bunch compression in order to meet the requisite beam intensities desired at the target. The longitudinal compression of an ion bunch is achieved by imposing an initial axial velocity tilt on the drifting beam and subsequently neutralizing its space-charge and current in a drift region filled with high-density plasma. The Neutralized Drift Compression Experiment (NDCX) at Lawrence Berkeley National Laboratory has measured a sixty-fold longitudinal current compression of an intense ion beam with pulse duration of a few nanoseconds, in agreement with simulations and theory. A strong solenoid is modeled near the end of the drift region in order to transversely focus the beam to a sub-millimeter spot size coincident with the longitudinal focal plane. The charge and current neutralization provided by the background plasma is critical in determining the total achievable transverse and longitudinal compression of the beam pulse. Numerical simulations show that the current density of an NDCX ion beam can be compressed over a few meters by factors greater than 10 5 with peak beam density in excess of 10 14 cm -3 . The peak beam density sets a lower bound on the local plasma density required near the focal plane for optimal beam compression, since the simulations show stagnation of the compression when n beam >n plasma . Beam-plasma interactions can also have a deleterious effect on the compression physics and lead to the formation of nonlinear wave excitations in the plasma. Simulations that optimize designs for the simultaneous transverse and longitudinal focusing of an NDCX ion beam for future warm dense matter experiments are discussed

Modeling of finite systems irradiated by intense ultrashort hard X-ray pulses

Energy Technology Data Exchange (ETDEWEB)

Jurek, Zoltan [Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron, Notkestrasse 85, D-22607 Hamburg (Germany); Ziaja, Beata [Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron, Notkestrasse 85, D-22607 Hamburg (Germany); Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Krakow (Poland); Santra, Robin [Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron, Notkestrasse 85, D-22607 Hamburg (Germany); Department of Physics, University of Hamburg, Jungiusstrasse 9, 20355 Hamburg (Germany)

2013-07-01

Large number of experiments have already been carried out at the existing hard X-Ray Free-Electron Laser facilities (LCLS, SACLA) during the recent years. Their great success generates even higher anticipation for the forthcoming X-ray sources (European XFEL). Single molecule imaging and nanoplasma formation are the challenging projects with XFELs that investigate the interaction of finite, small objects, e.g. single molecules, atomic clusters with intense X-ray radiation. Accurate modelling of the time evolution of such irradiated systems is required in order to understand the current experiments and to inspire new directions of experimental investigation. In this presentation we report on our theoretical molecular-dynamics tool able to follow non-equilibrium dynamics within finite systems irradiated by intense X-ray pulses. We introduce the relevant physical processes, present computational methods used, discuss their limitations and also the specific constraints on calculations imposed by experimental conditions. Finally, we conclude with a few simulation examples.

A VUV prism spectrometer for RICH radiator refractometry

CERN Document Server

Moyssides, P G; Fokitis, E

2000-01-01

A prism spectrometer has been developed to operate in the VUV wavelength range from 120 to 200 nm. It can be used as a pre- disperser in conjunction with a Fabry-Perot based gas refractometer. This instrument has also been used to measure the refractive index of the liquid radiator C/sub 6/F/sub 14/ in various spectral lines. This radiator is used in the RICH detectors of the DELPHI experiment and has been proposed for ALICE, and LHCb experiments. The spectral resolution of the system is improved as the wavelength decreases and the data are consistent with a wavelength accuracy about 0.4 nm at 140 nm. The results for the dispersion curve of the above liquid are presented. (17 refs).

Generation and focusing of pulsed intense ion beams. Progress report, April 1, 1979-September 30, 1979

International Nuclear Information System (INIS)

Sudan, R.N.; Hammer, D.A.

1981-04-01

Theoretical calculations suggest that an intense pulsed approx. 1 MeV proton beam can be used to simulate the characteristics of approx. 1 GeV heavy ion beam propagation in an inertial confinement fusion reactor chamber. Given the present availability of the former beams and the high projected cost for obtaining the latter ones, such experimental simulations appear appropriate. Work was undertaken under the cited contract to apply the technology of intense proton beams to this end. The first task was the development of a high brightness pulsed proton source which could produce a weakly convergent approx. 10 kA proton beam in a field free drift region. This was accomplished at approx. 250 keV, and preliminary beam propagation experiments were performed. It was concluded that a proper simulation experiment would require a higher voltage beam. An upgraded version of the existing generator, which would have produced a 30 kA beam at about 500 keV, and further propagation experiments were proposed as part of our unsuccessful renewal proposal dated October 15, 1979

Vacuum-ultraviolet (VUV) photoionization of small methanol and methanol-water clusters

International Nuclear Information System (INIS)

Ahmed, Musahid; Ahmed, Musahid; Wilson, Kevin R.; Belau, Leonid; Kostko, Oleg

2008-01-01

In this work we report on the vacuum-ultraviolet (VUV) photoionization of small methanol and methanol-water clusters. Clusters of methanol with water are generated via co-expansion of the gas phase constituents in a continuous supersonic jet expansion of methanol and water seeded in Ar. The resulting clusters are investigated by single photon ionization with tunable vacuum ultraviolet synchrotron radiation and mass analyzed using reflectron mass spectrometry. Protonated methanol clusters of the form (CH3OH)nH + (n=1-12) dominate the mass spectrum below the ionization energy of the methanol monomer. With an increase in water concentration, small amounts of mixed clusters of the form (CH3OH)n(H2O)H + (n=2-11) are detected. The only unprotonated species observed in this work are the methanol monomer and dimer. Appearance energies are obtained from the photoionization efficiency (PIE) curves for CH3OH +, (CH 3OH)2 +, (CH3OH)nH + (n=1-9), and (CH 3OH)n(H2O)H + (n=2-9 ) as a function of photon energy. With an increase in the water content in the molecular beam, there is an enhancement of photoionization intensity for methanol dimer and protonated methanol monomer at threshold. These results are compared and contrasted to previous experimental observations

Intensity of diffracted X-rays from biomolecules with radiation damage caused by strong X-ray pulses

International Nuclear Information System (INIS)

Kai, Takeshi; Tokuhisa, Atsushi; Moribayashi, Kengo; Fukuda, Yuji; Kono, Hidetoshi; Go, Nobuhiro

2014-01-01

In order to realize the coherent X-ray diffractive imaging of single biomolecules, the diffraction intensities, per effective pixel of a single biomolecule with radiation damage, caused by irradiation using a strong coherent X-ray pulse, were examined. A parameter survey was carried out for various experimental conditions, using a developed simulation program that considers the effect of electric field ionization, which was slightly reported on in previous studies. The two simple relationships among the parameters were identified as follows: (1) the diffraction intensity of a biomolecule slightly increases with the incident X-ray energy; and that (2) the diffraction intensity is approximately proportional to the target radius, when the radius is longer than 400 Å, since the upper limit of the incident intensity for damage to the biomolecules marginally changes with respect to the target radius. (author)

A quantum-rovibrational-state-selected study of the proton-transfer reaction H2+(X2Σ: v+ = 1-3; N+ = 0-3) + Ne → NeH+ + H using the pulsed field ionization-photoion method: observation of the rotational effect near the reaction threshold.

Science.gov (United States)

Xiong, Bo; Chang, Yih-Chung; Ng, Cheuk-Yiu

2017-07-19

Using the sequential electric field pulsing scheme for vacuum ultraviolet (VUV) laser pulsed field ionization-photoion (PFI-PI) detection, we have successfully prepared H 2 + (X 2 Σ: v + = 1-3; N + = 0-5) ions in the form of an ion beam in single quantum-rovibrational-states with high purity, high intensity, and narrow laboratory kinetic energy spread (ΔE lab ≈ 0.05 eV). This VUV-PFI-PI ion source, when coupled with the double-quadrupole double-octupole ion-molecule reaction apparatus, has made possible a systematic examination of the vibrational- as well as rotational-state effects on the proton transfer reaction of H 2 + (X 2 Σ: v + ; N + ) + Ne. Here, we present the integral cross sections [σ(v + ; N + )'s] for the H 2 + (v + = 1-3; N + = 0-3) + Ne → NeH + + H reaction observed in the center-of-mass kinetic energy (E cm ) range of 0.05-2.00 eV. The σ(v + = 1, N + = 1) exhibits a distinct E cm onset, which is found to agree with the endothermicity of 0.27 eV for the proton transfer process after taking into account of experimental uncertainties. Strong v + -vibrational enhancements are observed for σ(v + = 1-3, N + ) in the E cm range of 0.05-2.00 eV. While rotational excitations appear to have little effect on σ(v + = 3, N + ), a careful search leads to the observation of moderate N + -rotational enhancements at v + = 2: σ(v + = 2; N + = 0) quantum dynamics predictions. We hope that these new experimental results would further motivate more rigorous theoretical calculations on the dynamics of this prototypical ion-molecule reaction.

High-intensity laser physics

International Nuclear Information System (INIS)

Mohideen, U.

1993-01-01

This thesis is a study of the effect of high intensity lasers on atoms, free electrons and the generation of X-rays from solid density plasmas. The laser produced 50 milli Joule 180 femto sec pulses at 5 Hz. This translates to a maximum intensity of 5 x 10 18 W/cm 2 . At such high fields the AC stark shifts of atoms placed at the focus is much greater than the ionization energy. The characteristics of multiphoton ionization of atoms in intense laser fields was studied by angle resolved photoelectron spectroscopy. Free electrons placed in high intensity laser fields lead to harmonic generation. This phenomenon of Nonlinear Compton Scattering was theoretically investigated. Also, when these high intensity pulses are focused on solids a hot plasma is created. This plasma is a bright source of a short X-ray pulse. The pulse-width of X-rays from these solid density plasmas was measured by time-resolved X-ray spectroscopy

Computational efficiency improvement with Wigner rotation technique in studying atoms in intense few-cycle circularly polarized pulses

International Nuclear Information System (INIS)

Yuan, Minghu; Feng, Liqiang; Lü, Rui; Chu, Tianshu

2014-01-01

We show that by introducing Wigner rotation technique into the solution of time-dependent Schrödinger equation in length gauge, computational efficiency can be greatly improved in describing atoms in intense few-cycle circularly polarized laser pulses. The methodology with Wigner rotation technique underlying our openMP parallel computational code for circularly polarized laser pulses is described. Results of test calculations to investigate the scaling property of the computational code with the number of the electronic angular basis function l as well as the strong field phenomena are presented and discussed for the hydrogen atom

Predicting dynamic range and intensity discrimination for electrical pulse-train stimuli using a stochastic auditory nerve model: the effects of stimulus noise.

Science.gov (United States)

Xu, Yifang; Collins, Leslie M

2005-06-01

This work investigates dynamic range and intensity discrimination for electrical pulse-train stimuli that are modulated by noise using a stochastic auditory nerve model. Based on a hypothesized monotonic relationship between loudness and the number of spikes elicited by a stimulus, theoretical prediction of the uncomfortable level has previously been determined by comparing spike counts to a fixed threshold, Nucl. However, no specific rule for determining Nucl has been suggested. Our work determines the uncomfortable level based on the excitation pattern of the neural response in a normal ear. The number of fibers corresponding to the portion of the basilar membrane driven by a stimulus at an uncomfortable level in a normal ear is related to Nucl at an uncomfortable level of the electrical stimulus. Intensity discrimination limens are predicted using signal detection theory via the probability mass function of the neural response and via experimental simulations. The results show that the uncomfortable level for pulse-train stimuli increases slightly as noise level increases. Combining this with our previous threshold predictions, we hypothesize that the dynamic range for noise-modulated pulse-train stimuli should increase with additive noise. However, since our predictions indicate that intensity discrimination under noise degrades, overall intensity coding performance may not improve significantly.

Effect on structure and mechanical property of tungsten irradiated by high intensity pulsed ion beam

Science.gov (United States)

Mei, Xianxiu; Zhang, Xiaonan; Liu, Xiaofei; Wang, Younian

2017-09-01

The anti-thermal radiation performance of tungsten was investigated by high intensity pulsed ion beam technology. The ion beam was mainly composed of Cn+ (70%) and H+ (30%) at an acceleration voltage of 250 kV under different energy densities for different number of pulses. GIXRD analysis showed that no obvious phase structural changes occurred on the tungsten, and microstress generated. SEM analysis exhibited that there was no apparent irradiation damage on the surface of tungsten at the low irradiation frequency (3 times and 10 times) and at the low energy density (0.25 J/cm2 and 0.7 J/cm2). Cracks appeared on the surface of tungsten after 100-time and 300-time irradiation. Shedding phenomenon even appeared on the surface of tungsten at the energy densities of 1.4 J/cm2 and 2.0 J/cm2. The surface nano-hardness of tungsten decreased with the increase of the pulse times and the energy density. The tungsten has good anti-thermal radiation properties under certain heat load environment.

Dynamics of intense pulsed proton beam in the Nagaoka ETIGO-I

International Nuclear Information System (INIS)

Tanaka, Hajime; Konno, Kohji; Masugata, Katsumi; Yatsui, Kiyoshi; Matsui, Masao

1982-01-01

Dynamics of an intense pulsed proton beam have been studied by measuring nuclear reactions as well as by a biased ion-collector (BIC). When the ion-current density (Jsub(i)) is small such that Jsub(i) lt 30 A/cm 2 , the proton numer measured by BIC is in good agreement with that by nuclear activation. Good linearity exists between time integrated gamma -ray signal and proton number measured by the activation. Hence, it would be possible to obtain the proton number quantitatively even when a target ''blow-off'' takes place at Jsub(i) gt 1 kA/cm 2 . Prompt gamma -ray is also measured by the time-of-flight method to yield reasonable agreement with the applied peak potential. (author)

Comparative evaluation of transmembrane ion transport due to monopolar and bipolar nanosecond, high-intensity electroporation pulses based on full three-dimensional analyses

Science.gov (United States)

Hu, Q.; Joshi, R. P.

2017-07-01

Electric pulse driven membrane poration finds applications in the fields of biomedical engineering and drug/gene delivery. Here we focus on nanosecond, high-intensity electroporation and probe the role of pulse shape (e.g., monopolar-vs-bipolar), multiple electrode scenarios, and serial-versus-simultaneous pulsing, based on a three-dimensional time-dependent continuum model in a systematic fashion. Our results indicate that monopolar pulsing always leads to higher and stronger cellular uptake. This prediction is in agreement with experimental reports and observations. It is also demonstrated that multi-pronged electrode configurations influence and increase the degree of cellular uptake.

Electrons in a relativistic-intensity laser field: generation of zeptosecond electromagnetic pulses and energy spectrum of the accelerated electrons

International Nuclear Information System (INIS)

Andreev, A A; Galkin, A L; Kalashnikov, M P; Korobkin, V V; Romanovsky, Mikhail Yu; Shiryaev, O B

2011-01-01

We study the motion of an electron and emission of electromagnetic waves by an electron in the field of a relativistically intense laser pulse. The dynamics of the electron is described by the Newton equation with the Lorentz force in the right-hand side. It is shown that the electrons may be ejected from the interaction region with high energy. The energy spectrum of these electrons and the technique of using the spectrum to assess the maximal intensity in the focus are analysed. It is found that electromagnetic radiation of an electron moving in an intense laser field occurs within a small angle around the direction of the electron trajectory tangent. The tangent quickly changes its direction in space; therefore, electromagnetic radiation of the electron in the far-field zone in a certain direction in the vicinity of the tangent is a short pulse with a duration as short as zeptoseconds. The calculation of the temporary and spectral distribution of the radiation field is carried out. (superintense laser fields)

Laser-energy scaling law for neutrons generated from nano particles Coulomb-exploded by intense femtosecond laser pulses

International Nuclear Information System (INIS)

Sakabe, Shuji; Hashida, Masaki

2015-01-01

To discuss the feasibility of compact neutron sources the yield of laser produced neutrons is scaled by the laser energy. High-energy ions are generated by Coulomb explosion of clusters through intense femtosecond laser-cluster interactions. The laser energy scaling law of the neutron yield is estimated using the laser intensity scaling law for the energy of ions emitted from clusters Coulomb-exploded by an intense laser pulse. The neutron yield for D (D, n) He shows the potential of compact neutron sources with modern laser technology, and the yield for p (Li, n) Be shows much higher than that for Li (p, n) Be with the assumption of 500 nm-class cluster Coulomb explosion. (author)

The doppler frequency shift caused by the inhomogeneities of a medium induced by pulses of intense laser radiation

Science.gov (United States)

Rozanov, N. N.; Kiselev, Al. S.; Kiselev, An. S.

2008-08-01

Self-reflection of pulses of intense laser radiation from an inhomogeneity induced by them in a medium with fast optical nonlinearity is analyzed. The reflected radiation is characterized by a considerable Doppler shift and by a signal magnitude that is sufficient for experimental detection.

[Pulse flows of populations of cortical neurons under low-intensity pulsed microwave: interspike intervals].

Science.gov (United States)

Chizhenkova, R A

2014-01-01

Pulse flows of populations of cortical neurons were investigated on unanesthetized nonimmobilized rabbits prior, during, and after 1-min microwave irradiation (wavelength 37.5 cm, power density 0.5-1.0 mW/cm2) in continuous and pulse-modulated modes with a frequency of 5, 20 and 100 Hz. The changes in the characteristics of interspike intervals resulted from these exposures. The peculiarity of rearrangements of pulse flows and their dynamics was determined by modes of irradiation.

Cavitation enhances coagulated size during pulsed high-intensity focussed ultrasound ablation in an isolated liver perfusion system.

Science.gov (United States)

Zhao, Lu-Yan; Liu, Shan; Chen, Zong-Gui; Zou, Jian-Zhong; Wu, Feng

2016-11-24

To investigate whether cavitation enhances the degree of coagulation during pulsed high-intensity focussed ultrasound (HIFU) in an isolated liver perfusion system. Isolated liver was treated by pulsed HIFU or continuous-wave HIFU with different portal vein flow rates. The cavitation emission during exposure was recorded, and real-time ultrasound images were used to observe changes in the grey scale. The coagulation size was measured and calculated. HIFU treatment led to complete coagulation necrosis and total cell destruction in the target regions. Compared to exposure at a duty cycle (DC) of 100%, the mean volumes of lesions induced by 6 s exposure at DCs of 50% and 10% were significantly larger (P cavitation activity for the pulsed-HIFU (P > .05). For continuous-wave HIFU exposure, there was a significant decrease in the necrosis volume and cavitation activity for exposure times of 1, 2, 3, 4, and 6 s with increasing portal perfusion rates. Perfusion flow rates negatively influence cavitation activity and coagulation volume. Ablation is significantly enhanced during pulsed HIFU exposure compared with continuous-wave HIFU.

Ultra-intense laser pulse propagation in plasmas: from classic hole-boring to incomplete hole-boring with relativistic transparency

International Nuclear Information System (INIS)

Weng, S M; Murakami, M; Mulser, P; Sheng, Z M

2012-01-01

Relativistic laser pulse propagation into homogeneous plasmas has been investigated as a function of plasma density. At first, the propagation features are compared systematically between relativistic transparency (RT) and hole-boring (HB). Paramountly, a considerably broad intermediate regime, namely the incomplete HB regime, has been found between the RT regime and the HB regime for an extremely intense circularly polarized (CP) pulse. In this regime HB proceeds in collaboration with RT, resulting in a much faster propagation speed and a higher cut-off energy of fast ions than in the classic HB regime. Similarly to the classic HB regime, formulae are presented to model the laser propagation and the ion acceleration according to the modified momentum flux balance in this incomplete HB regime. The simulations give the density boundary between this incomplete HB regime and the classic HB regime for CP pulses, which is crucial for estimating the maximum mean ion energy and the maximum conversion efficiency that can be achieved by the classic HB acceleration at a given laser intensity. For linear polarization (LP) the propagation mechanism apparently undergoes a transition in time between these two regimes. A detailed comparison between LP and circular polarization is made for these phenomena. (paper)

Enhancement of beam pulse controllability for a single-pulse formation system of a cyclotron

International Nuclear Information System (INIS)

Kurashima, Satoshi; Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Okumura, Susumu; Taguchi, Mitsumasa; Fukuda, Mitsuhiro

2015-01-01

The single-pulse formation technique using a beam chopping system consisting of two types of high-voltage beam kickers was improved to enhance the quality and intensity of the single-pulse beam with a pulse interval over 1 μs at the Japan Atomic Energy Agency cyclotron facility. A contamination rate of neighboring beam bunches in the single-pulse beam was reduced to less than 0.1%. Long-term purification of the single pulse beam was guaranteed by the well-controlled magnetic field stabilization system for the cyclotron magnet. Reduction of the multi-turn extraction number for suppressing the neighboring beam bunch contamination was achieved by restriction of a beam phase width and precise optimization of a particle acceleration phase. In addition, the single-pulse beam intensity was increased by a factor of two or more by a combination of two types of beam bunchers using sinusoidal and saw-tooth voltage waveforms. Provision of the high quality intense single-pulse beam contributed to improve the accuracy of experiments for investigation of scintillation light time-profile and for neutron energy measurement by a time-of-flight method

PULSED MOLECULAR BEAM PRODUCTION WITH NOZZLES

Energy Technology Data Exchange (ETDEWEB)

Hagena, Otto-Friedrich

1963-05-15

Molecular beam experiments that can be carried out in pulsed operation may be performed at considerably reduced expense for apparatus if, for pulse generation, the gas supply to the beam production system is interrupted as opposed to the usual steady molecular beam. This technique is studied by measuring intensity vs time of molecular beam impulses of varying length, how fast and through which intermediate states the initial intensity of the impulse attains equilibrium, and in which way the intensity of the molecular-beam impulse is affected by the pulse length and by increasing pressure in the first pressure stage. For production of pulses, a magnetically actuated, quick shutting, valve is used whose scaling area is the inlet cone of the nozzle used for the beam generation. The shortest pulses produced had a pulse length of 1.6 ms. (auth)

Analytical evaluation of neutron diffusion equation for the geometry of very intense continuous high flux pulsed reactor

International Nuclear Information System (INIS)

Narain, Rajendra

1995-01-01

Using the concept of Very Intense Continuous High Flux Pulsed Reactor to obtain a rotating high flux pulse in an annular core an analytical treatment for the quasi-static solution with a moving reflector is presented. Under quasi-static situation, time averaged values for important parameters like multiplication factor, flux, leakage do not change with time. As a result the instantaneous solution can be considered to be separable in time and space after correcting for the coordinates for the motion of the pulser. The space behaviour of the pulser is considered as exp(-αx 2 ). Movement of delayed neutron precursors is also taken into account. (author). 4 refs

High resolution VUV matrix isolation spectroscopy using synchrotron radiation: N2 in Ne

International Nuclear Information System (INIS)

Guertler, P.; Koch, E.E.

1980-01-01

We have investigated the VUV absorption spectrum of nitrogen in a neon matrix exploiting the intense synchrotron radiation continuum of the storage ring DORIS and the high resolving power of a 3 m normal incidence monochromator. With an improved sample preparation technique we were able to observe both the allowed transitions b 1 PIsub(u) and b 1 Σ + sub(u) between 12.4 and 14.0 eV and even the forbidden transitions w 1 Δsub(u) and a 1 PIsub(g) between 8.0 and 11.0 eV. All four transitions consist of long progressions of sharp bands (GAMMA approx. 10 meV) which are deperturbed in the matrix due to the suppression of nearby Rydberg states. Using symmetry arguments, our analysis of the spectra leads us to the conclusion that the N 2 molecule is oriented along the (1,1,1) direction in the host lattice. A detailed fine structure is observed for most bands of the first time. This fine structure is caused by dynamical interactions of the excited molecules with the matrix and is interpreted as excitation of librational modes of the N 2 molecule and a selective coupling to phonon modes of the neon lattice. (orig.)

Pulse low-intensity electromagnetic field as prophylaxis of heterotopic ossification in patients with traumatic spinal cord injury

Directory of Open Access Journals (Sweden)

Đurović Aleksandar

2009-01-01

Full Text Available Background/Aim. Heterotopic ossification (HO is an important complication of head and spinal cord injuries (SCI. Pulse low-intensity electromagnetic field (PLIMF therapy increases blood flow to an area of pain or inflammation, bringing more oxygen to that area and helps to remove toxic substances. The aim of this study was to determine the effect of PLIMF as prophylaxis of HO in patients with SCI. Methods. This prospective random control clinical study included 29 patients with traumatic SCI. The patients were randomly divided into experimental (n = 14 and control group (n = 15. The patients in the experimental group, besides exercise and range of motion therapy, were treated by PLIMF of the following characteristics: induction of 10 mT, frequency of 25 Hz and duration of 30 min. Pulse low-intensity electromagnetic field therapy started in the 7th week after the injury and lasted 4 weeks. The presence or absence of HO around the patients hips we checked by a plane radiography and Brookers classification. Functional capabilities and motor impairment were checked by Functional Independent Measure (FIM, Barthel index and American Spinal Injury Association (ASIA impairment class. Statistic analysis included Kolmogorov-Smirnov test, Shapiro-Wilk test, Mann Whitney Exact test, Exact Wilcoxon signed rank test and Fischer Exact test. Statistical significance was set up to p < 0.05. Results. At the end of the treatment no patient from the experimental group had HO. In the control group, five patients (33.3% had HO. At the end of the treatment the majority of the patients from the experimental group (57.14% moved from ASIA-A to ASIA-B class. Conclusion. Pulse low-intensity electromagnetic field therapy could help as prophylaxis of HO in patients with traumatic SCI.

Reaction of congo red in water after irradiation by pulsed intense relativistic electron beam

International Nuclear Information System (INIS)

Kikuchi, Takashi; Kondo, Hironobu; Sasaki, Toru; Harada, Nob.; Moriwaki, Hiroshi; Nakanishi, Hiromitsu; Imada, Go

2011-01-01

The reaction of congo red, a well-known toxic azo dye, occurred after irradiation by a pulsed intense relativistic electron beam (PIREB). An aquation of congo red was irradiated by PIREB (2 MeV, 0.36 kA, 140 ns). After PIREB irradiation, the solution was measured by electrospray ionization-mass spectrometry and liquid chromatography/mass spectrometry. It was found that congo red underwent a reaction (77% conversion after five shots of PIREB irradiation) and the hydroxylated compounds of the dye were observed as reaction products. (author)

Recent advances in incoherent light sources in the vacuum-ultraviolet (88-200nm) based on electric discharge plasmas

International Nuclear Information System (INIS)

Ward, B.K.; Carman, R.J.; Mildren, R.P.; Kane, D.M.

2004-01-01

Full text: Rare-gas and rare gas-halide excimer lamps are powerful, frequency agile, mercury-free sources of high power, narrow band (10nm-30nm), UV and VUV radiation covering the wavelength range 88nm-320nm. A very efficient and practically convenient method of excitation is achieved using the dielectric barrier discharge (DBD). In the DBD, charge build-up on an insulating (dielectric) barrier at one or both of the electrodes provides an intrinsic mechanism for quenching the discharge before the transition to a high current discharge. The UV/VUV output from rare-gas DBD lamps is highly monochromatic, derived predominantly from 2nd excimer continuum, with negligible output at visible and infrared wavelengths. For DBD lamps powered by sinusoidal voltage waveforms (50Hz-100kHz), the electrical to optical conversion efficiency typically reaches 10-20%. The discharge structure consists of multiple transient plasma aments that occur stochastically in time during the discharge cycle leading to VUV output pulses with irregular spacing and amplitude. We have shown, however, that using discrete high-voltage pulses of relatively short duration, produces a short-lived homogeneous discharge that generates much higher peak power from short (sub-microsecond) VUV output pulses, with an additional increase (two- fold) in overall efficiency. Conversion efficiencies between 40-60% have also been reported for short-pulse excitation techniques. Efficient generation of pulsed, high peak-power VUV output is of interest for a broad range of applications in time-resolved spectroscopy, photo-lithography, materials processing and surface modification/cleaning, killing of micro- organisms and bacteria, sterilization, and in ozone production for water purification

Pulse-coupled neural nets: translation, rotation, scale, distortion, and intensity signal invariance for images.

Science.gov (United States)

Johnson, J L

1994-09-10

The linking-field neural network model of Eckhorn et al. [Neural Comput. 2, 293-307 (1990)] was introduced to explain the experimentally observed synchronous activity among neural assemblies in the cat cortex induced by feature-dependent visual activity. The model produces synchronous bursts of pulses from neurons with similar activity, effectively grouping them by phase and pulse frequency. It gives a basic new function: grouping by similarity. The synchronous bursts are obtained in the limit of strong linking strengths. The linking-field model in the limit of moderate-to-weak linking characterized by few if any multiple bursts is investigated. In this limit dynamic, locally periodic traveling waves exist whose time signal encodes the geometrical structure of a two-dimensional input image. The signal can be made insensitive to translation, scale, rotation, distortion, and intensity. The waves transmit information beyond the physical interconnect distance. The model is implemented in an optical hybrid demonstration system. Results of the simulations and the optical system are presented.

Efficient energy absorption of intense ps-laser pulse into nanowire target

Energy Technology Data Exchange (ETDEWEB)

Habara, H.; Honda, S.; Katayama, M.; Tanaka, K. A. [Graduate School of Engineering, Osaka University, 2-1 Suita, Osaka 565-0871 (Japan); Sakagami, H. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Nagai, K. [Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Nagatsuda 4259, Midori-ku, Yokohama 226-8503, Kanagawa (Japan)

2016-06-15

The interaction between ultra-intense laser light and vertically aligned carbon nanotubes is investigated to demonstrate efficient laser-energy absorption in the ps laser-pulse regime. Results indicate a clear enhancement of the energy conversion from laser to energetic electrons and a simultaneously small plasma expansion on the surface of the target. A two-dimensional plasma particle calculation exhibits a high absorption through laser propagation deep into the nanotube array, even for a dense array whose structure is much smaller than the laser wavelength. The propagation leads to the radial expansion of plasma perpendicular to the nanotubes rather than to the front side. These features may contribute to fast ignition in inertial confinement fusion and laser particle acceleration, both of which require high current and small surface plasma simultaneously.

Phase-Space Tomography of Giant Pulses in Storage Ring FEL Theory and Experiment

CERN Document Server

Chalut, K

2005-01-01

The use of giant pulses in storage ring FEL provides for high peak power at the fundamental wavelength and for effective generating of high VUV harmonics. This process is accompanied by a complex nonlinear dynamics of electron beam, which cannot be described by simple models. In this paper we compare the results of numerical simulations, performed by self-consistent #uvfel code, with experimental observations of electron beam evolution in the longitudinal phase space. The evolution of the electron beam distribution was obtained from the images recorded by dual-sweep streak-camera. The giant pulse process occurs on a short fast time scale compared with synchrotron oscillation period, which make standard methods of tomography inapplicable. We had developed a novel method of reconstruction, an SVD-Based Phase-Space Tomography, which allows to reconstruct phase space distribution from as few as two e-bunch profiles separated by about 3 degrees of rotation in the phase space. This technique played critical role in...

UCN up-scattering as a source of highly intense monochromatic pulsed beams

International Nuclear Information System (INIS)

Rauch, H.; Geltenborg, P.; Zimmer, O.

2011-01-01

The present proposal opens new possibilities to increase the usable neutron flux by advanced neutron cooling and phase space transformation methods. Thus a new instrument should be installed where the available neutron flux is used more efficiently. The essential point is an increase of phase space density and brilliance due to a more effective production of ultra-cold neutrons and a following transformation of these neutrons to higher energies. Recently reported progresses in the production of UCN's and in the up-scattering of such neutrons make the time mature to step towards a new method to produce high intense pulsed neutron beams. The up-scattering is made by fast moving Bragg crystals

Intense pulsed light treatment for dry eye disease due to meibomian gland dysfunction; a 3-year retrospective study.

Science.gov (United States)

Toyos, Rolando; McGill, William; Briscoe, Dustin

2015-01-01

The purpose of this study was to determine the clinical benefits of intense-pulsed-light therapy for the treatment of dry-eye disease caused by meibomian gland dysfunction (MGD). MGD is the leading cause of evaporative dry eye disease. It is currently treated with a range of methods that have been shown to be only somewhat effective, leading to the need for advanced treatment options. A retrospective noncomparative interventional case series was conducted with 91 patients presenting with severe dry eye syndrome. Treatment included intense-pulsed-light therapy and gland expression at a single outpatient clinic over a 30-month study. Pre/post tear breakup time data were available for a subset of 78 patients. For all patients, a specially developed technique for the treatment of dry eye syndrome was applied as a series of monthly treatments until there was adequate improvement in dry eye syndrome symptoms by physician judgment, or until patient discontinuation. Primary outcomes included change in tear breakup time, self-reported patient satisfaction, and adverse events. Physician-judged improvement in dry eye tear breakup time was found for 68 of 78 patients (87%) with seven treatment visits and four maintenance visits on average (medians), and 93% of patients reported post-treatment satisfaction with degree of dry eye syndrome symptoms. Adverse events, most typically redness or swelling, were found for 13% of patients. No serious adverse events were found. Although preliminary, study results of intense-pulsed-light therapy treatment for dry eye syndrome caused by meibomian gland dysfunction are promising. A multisite clinical trial with a larger sample, treatment comparison groups, and randomized controlled trials is currently underway.

Investigation of attosecond ionization dynamics in gases and solids with intense few-cycle laser pulses

International Nuclear Information System (INIS)

Mitrofanov, A. V.

2011-01-01

Interaction of intense light fields with dielectric materials has fascinated scientists since the invention of pulsed lasers in the early sixties. Despite the many decades of research, the interest in the field keeps growing because of the potential technological applications of optical (meta-) materials and the prospects of light-controlled peta-Hertz electronics as well as the improving understanding of the fundamental processes behind light-matter interactions. The progress in the short-pulse laser technology that delivered ever-shorter light pulses was echoed by the discoveries of different progressively shorter time scales in the cycle of excitation and energy/charge relaxation in transparent solids, many parts of which are now well understood. The ultimate challenge lies in recovering the earliest stages of the dynamics which are linked to optical-field-ionization that proceeds within a fraction of an optical cycle. One of the complications of advancing the attosecond science to the bulk media is the problem of inducing and detecting a synchronized attosecond response. The charged particles spectroscopy, well developed in gaseous media during last decade and capable of reaching an attosecond temporal resolution cannot be used as an experimental tool for investigation since direct detection of charged particles is impossible in the volume of a solid material. However, solids are the natural place where electronic processes on the sub-femtosecond or attosecond time scale are expected. Very recently several methods for measuring attosecond dynamics in condensed media have been proposed utilizing optical fields in the transparency range of the material. In this thesis a method, suggested in our scientific group is presented. It is an all-optical method based on the detection of optical harmonics originating from ultrafast modulation of a free electron current due to ionization in the field of intense few-cycle laser pulses. This technique will allow retrieving

Metabolite profiling of phenolic and carotenoid contents in tomatoes after moderate-intensity pulsed electric field treatments.

Science.gov (United States)

Vallverdú-Queralt, Anna; Oms-Oliu, Gemma; Odriozola-Serrano, Isabel; Lamuela-Raventós, Rosa M; Martín-Belloso, Olga; Elez-Martínez, Pedro

2013-01-01

A metabolite profiling approach was used to study the effect of moderate-intensity pulsed electric field (MIPEF) treatments on the individual polyphenol and carotenoid contents of tomato fruit after refrigeration at 4°C for 24h. The MIPEF processing variables studied were electric field strength (from 0.4 to 2.0kV/cm) and number of pulses (from 5 to 30). Twenty four hours after MIPEF treatments, an increase was observed in hydroxycinnamic acids and flavanones, whereas flavonols, coumaric and ferulic acid-O-glucoside were not affected. Major changes were also observed for carotenoids, except for the 5-cis-lycopene isomer, which remain unchanged after 24h of MIPEF treatments. MIPEF treatments, conducted at 1.2kV/cm and 30 pulses, led to the greatest increases in chlorogenic (152%), caffeic acid-O-glucoside (170%) and caffeic (140%) acids. On the other hand, treatments at 1.2kV/cm and 5 pulses led to maximum increases of α-carotene, 9- and 13-cis-lycopene, which increased by 93%, 94% and 140%, respectively. Therefore, MIPEF could stimulate synthesis of secondary metabolites and contribute to production of tomatoes with high individual polyphenol and carotenoid contents. Copyright © 2012 Elsevier Ltd. All rights reserved.

The upgrade of intense pulsed neutron source (IPNS) through the change of coolant and reflector

CERN Document Server

Baek, I C; Iverson, E B

2002-01-01

The current intense pulsed neutron source (IPNS) depleted uranium target is cooled by light water. The inner reflector material is graphite and the outer reflector material is beryllium. The presence of H sub 2 O in the target moderates neutrons and leads to a higher absorption loss in the target than is necessary. D sub 2 O coolant in the small quantities required minimizes this effect. We have studied the possible improvement in IPNS beam fluxes that would result from changing the coolant from H sub 2 O to D sub 2 O and the inner reflector from graphite to beryllium. Neutron intensities were calculated for directions normal to the viewed surface of each moderator for four different cases of combinations of target coolant and reflector materials. The simulations reported here were performed using the MCNPX (version 2.1.5) computer program. Our results show that substantial gains in neutron beam intensities can be achieved by appropriate combination of target coolant and reflector materials. The combination o...

Guiding of laser pulses in plasma waveguides created by linearly-polarized femtosecond laser pulses

OpenAIRE

Lemos, N.; Cardoso, L.; Geada, J.; Figueira, G.; Albert, F.; Dias, J. M.

2018-01-01

We experimentally demonstrate that plasma waveguides produced with ultra-short laser pulses (sub-picosecond) in gas jets are capable of guiding high intensity laser pulses. This scheme has the unique ability of guiding a high-intensity laser pulse in a plasma waveguide created by the same laser system in the very simple and stable experimental setup. A hot plasma column was created by a femtosecond class laser that expands into an on-axis parabolic low density profile suitable to act as a wav...

Photoluminescence of Eu{sup 2+}-doped CaMgSi{sub 2x}O{sub 6+2x} (1.00{<=}x{<=}1.20) phosphors in UV-VUV region

Energy Technology Data Exchange (ETDEWEB)

Zhang Zhiya [Department of Materials Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Wang Yuhua [Department of Materials Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China)], E-mail: wyh@lzu.edu.cn

2008-03-15

Alkaline-earth silicate phosphors CaMgSi{sub 2x}O{sub 6+2x}:Eu{sup 2+} (1.00{<=}x{<=}1.20) were prepared by traditional solid-state reaction. The phosphors showed an intense blue emission centered around 453 nm, with both 254 and 147 nm excitations. The host absorption below 200 nm in the excitation spectra consisted of two bands around 160 and 190 nm. The band around 160 nm was ascertained to be associated with the SiO{sub 4}-tetrahedra and MgO{sub 6}-polyhedra, and that around 190 nm was due to the CaO{sub 8}-polyhedra or some impurities. The incorporation of excess Si of less than 15% would not lead to formation of impurities and the results indicated that an appropriate Si excess could improve the Photoluminescence (PL) intensity in both ultraviolet (UV) and vacuum ultraviolet (VUV) regions.

High-intensity pulsed beam source with tunable operation mode

Science.gov (United States)

Nashilevskiy, A. V.; Kanaev, G. G.; Ezhov, V. V.; Shamanin, V. I.

2017-05-01

The report presents the design of an electron and an ion pulsed accelerator. The powerful high-voltage pulse generator of the accelerator and the vacuum bushing insulator is able to change the polarity of the output voltage. The low-inductance matching transformer provides an increase in the DFL output impedance by 4 times. The generator based on a high voltage pulse transformer and a pseudo spark switch is applied for DFL charging. The high-impedance magnetically insulated focusing diode with Br magnetic field and the “passive” anode was used to realize the ion beam generation mode. The plasma is formed on the surface of the anode caused by an electrical breakdown at the voltage edge pulse; as a result, the carbon ion and proton beam is generated. This beam has the following parameters: the current density is about 400 A/cm2 (in focus): the applied voltage is up to 450 kV. The accelerator is designed for the research on the interaction of the charged particle pulsed beams with materials and for the development of technological processes of a material modification.

Temporal Airy pulses control cell poration

Directory of Open Access Journals (Sweden)

S. Courvoisier

2016-07-01

Full Text Available We show that spectral phase shaping of fs-laser pulses can be used to optimize laser-cell membrane interactions in water environment. The energy and peak intensity thresholds required for cell poration with single pulse in the nJ range can be significantly reduced (25% reduction in energy and 88% reduction in peak intensity by using temporal Airy pulses, controlled by positive third order dispersion, as compared to bandwidth limited pulses. Temporal Airy pulses are also effective to control the morphology of the induced pores, with prospective applications from cellular to tissue opto-surgery and transfection.

Effect of low-intensity pulsed ultrasound on bone regeneration: biochemical and radiologic analyses.

Science.gov (United States)

Pomini, Karina T; Andreo, Jesus C; Rodrigues, Antonio de C; de O Gonçalves, Jéssica B; Daré, Letícia R; German, Iris J S; Rosa, Geraldo M; Buchaim, Rogerio L

2014-04-01

The purpose of this study was to evaluate the effects of low-intensity pulsed ultrasound at 1.0 MHz on the healing process of fractures with bone loss in the rat fibula by alkaline phosphate level measurement and radiologic analyses. Thirty 70-day-old male Wistar rats underwent a bone resection of 2.5 to 3.0 mm between the proximal and middle third of the right fibular diaphysis. The animals were randomly divided into 3 experimental groups: reference (uninjured), control (injured only), and treated (injured and treated with 5 applications of ultrasound, interspersed by 2 days of rest, beginning 24 hours after the osteotomy). Euthanasia was performed at experimental periods of 7 and 14 days. The right hind limb was removed for radiologic analysis. The blood was collected via cardiac puncture to determine the serum alkaline phosphatase activity. The bone fractures had not been completely consolidated in the treated and control group when analysis of the bone took place. At day 7, the serum alkaline phosphatase activity was higher in the treated group (mean ± SD, 72.17 ± 7.02 U/L) compared to the control (65.26 ± 8.41 U/L) and reference (67.21 ± 7.86 U/L) groups. At day 14, higher alkaline phosphatase activity was seen in the control group (68.96 ± 8.12 U/L) compared to the treated (66.09 ± 8.46 U/L) and reference (67.14 ± 7.96 U/L) groups. The biochemical and radiologic results suggest that low-intensity pulsed ultrasound can be used as an auxiliary method to consolidate fractures and probably reduces the bone healing time, offering clinical benefits.

Anomalous intensities of Ne-like ion resonance line in plasma produced by picosecond laser pulse

International Nuclear Information System (INIS)

Bryunetkin, B.A.; Skobelev, I.Yu.; Faenov, A.Ya.; Kalashnikov, M.P.; Nikles, P.; Shnyupep, M.

1995-01-01

An anomalous structure of intensities of spectral lines of CuXX and GeXXX Ne-like ions emitted by plasma produced by laser pulses of picosecond duration and up to 2x10 18 W/cm 2 flux density is recorded for the first time. It is shown that spectrum maximum of these ions is emitted from a plasma region whose density is significantly above the critical value of the length of heating laser radiation wave. 9 refs.; 3 figs

VUV photoionization of acetamide studied by electron/ion coincidence spectroscopy in the 8–24 eV photon energy range

International Nuclear Information System (INIS)

Schwell, Martin; Bénilan, Yves; Fray, Nicolas; Gazeau, Marie-Claire; Es-Sebbar, Et.; Garcia, Gustavo A.; Nahon, Laurent; Champion, Norbert; Leach, Sydney

2012-01-01

Highlights: ► We study the VUV photoionization of acetamide in the 8–24 eV photon energy range. ► Electron/ion coincidence measurements are performed using synchrotron radiation. ► The adiabatic ionization energy of acetamide is determined by TPEPICO measurements. ► VUV induced fragmentation pathways of acetamide are assigned and discussed. - Abstract: A VUV photoionization study of acetamide was carried out over the 8–24 eV photon energy range using synchrotron radiation and photoelectron/photoion coincidence (PEPICO) spectroscopy. Threshold photoelectron photoion coincidence (TPEPICO) measurements were also made. Photoion yield curves and branching ratios were measured for the parent ion and six fragment ions. The adiabatic ionization energy of acetamide was determined as I.E. (1 2 A′) = (9.71 ± 0.02) eV, in agreement with an earlier reported photoionization mass spectrometry (PIMS) value. The adiabatic energy of the first excited state of the ion, 1 2 A″, was determined to be ≈10.1 eV. Assignments of the fragment ions and the pathways of their formation by dissociative photoionization were made. The neutral species lost in the principal dissociative photoionization processes are CH 3 , NH 2 , NH 3 , CO, HCCO and NH 2 CO. Heats of formation are derived for all ions detected and are compared with literature values. Some astrophysical implications of these results are discussed.

VUV Spectroscopy in DIII-D Divertor

International Nuclear Information System (INIS)

Alkesh Punjabi; Nelson Jalufka

2004-01-01

The research carried out on this grant was motivated by the high power emission from the CIV doublet at 155 nm in the DIII-D divertor and to study the characteristics of the radiative divertor. The radiative divertor is designed to reduce the heat load to the target plates of the divertor by reducing the energy in the divertor plasma using upstream scrape-off-layer (SOL) radiation. In some cases, particularly in Partially Detached Divertor (PDD) operations, this emission accounts for more than 50% of the total radiation from the divertor. In PDD operation, produced by neutral gas injection, the particle flow to the target plate and the divertor temperature are significantly reduced. A father motivation was to study the CIV emission distribution in the lower, open divertor and the upper baffled divertor. Two Vacuum Ultra Violet Tangential viewing Television cameras (VUV TTV) were constructed and installed in the upper, baffled and the lower, open divertor. The images recorded by these cameras were then inverted to produce two-dimensional distributions of CIV in the poloidal plane. Results obtained in the project are summarized in this report

Effects of photoirradiation in UV and VUV regions during plasma exposure to polymers

International Nuclear Information System (INIS)

Cho, Ken; Setsuhara, Yuichi; Takenaka, Kosuke; Shiratani, Masaharu; Sekine, Makoto; Hori, Masaru

2011-01-01

Interactions between photons irradiated from Ar-O 2 mixture plasmas and polymer surfaces were investigated on the basis of depth analyses of chemical bonding states in the nano-surface layer of polyethylene terephthalate (PET) films via hard X-ray photoelectron spectroscopy (HXPES) and conventional X-ray photoelectron spectroscopy (XPS). The PET films were exposed to photons from the Ar-O 2 mixture plasmas by covering the PET samples with MgF 2 and quartz windows as optical filters for evaluation of photoirradiation effects in ultraviolet (UV) and vacuum ultraviolet (VUV) regions. The HXPES results indicated that the degradation of the chemical bonding states due to photoirradiation in regions was insignificant in deeper regions up to about 50 nm from the surface. Whereas, conventional XPS analysis showed that C-O bond, O=C-O bond and C=O bond increased after photoirradiation in UV and VUV regions. These results suggest that the increase in oxygen functionalities (C-O bond, O=C-O bond and C=O bond) may be attributed to chemical reactions and/or terminations of scissed bonds via photodecompositions of the polymer with oxygen and/or OH species (oxygen molecules and radicals during plasma exposure and/or oxygen molecules and moisture after taking the PET samples out of the plasma reactor to the ambient air) in the vicinity of the sample surface.

Experimental and theoretical studies of the physical processes occurring in thin plane targets irradiated by intense X-ray pulses

International Nuclear Information System (INIS)

Bugrov, A. E.; Burdonskii, I. N.; Gavrilov, V. V.; Gol'tsov, A. Yu.; Grabovskii, E. V.; Efremov, V. P.; Zhuzhukalo, E. V.; Zurin, M. V.; Koval'skii, N. G.; Kondrashov, V. N.; Oleinik, G. M.; Potapenko, A. I.; Samokhin, A. A.; Smirnov, V. P.; Fortov, V. E.; Frolov, I. N.

2007-01-01

Results are presented from experimental and theoretical studies of the interaction of intense X-ray pulses with different types of plane targets, including low-density (∼10 mg/cm 3 ) ones, in the Angara-5-1 facility. It is found experimentally that a dense low-temperature plasma forms on the target surface before the arrival of the main heating X-ray pulse. It is demonstrated that the contrast of the X-ray pulse can be increased by placing a thin organic film between the target and the discharge gap. The expansion velocity of the plasma created on the target surface irradiated by Z-pinch-produced X rays was found to be (3-4) x 10 6 cm/s. A comparison between the simulation and experimental results confirms the validity of the physical-mathematical model used

Hematoporphyrin-sensitized degradation of deoxyribose and DNA in high intensity near-UV picosecond pulsed laser photolysis

International Nuclear Information System (INIS)

Gantchev, T.G.; Lier, J.E. van; Grabner, G.; Keskinova, E.; Angelov, D.

1995-01-01

The photosensitized degradation of deoxyribose and DNA, using hematoporphyrin (HP) and picosecond laser pulses at high intensities was studied. Aldehyde formation from 2-deoxy-D-ribose and long-chain double-stranded DNA, when analyzed as a function of light intensity, followed a non-linear dependence, suggesting the involvement of multiphoton light absorption by HP. The degradation mechanism was studied by analysis of the yield dependence on excitation intensity and the effect of added radical scavengers. The participation of OH radicals in the degradation process was confirmed by spin trapping techniques. At low light intensities, added N 2 O largely increased product formation, suggesting that HP photoionization predominates under these conditions. At higher intensities (I ≥ 3 GW/cm 2 ) the product yield was not affected by N 2 O which, combined with spin trapping data, suggested that OH radical formation occurred, but that neither HP photoionization nor peroxy formation was involved. Single and double strand breaks in supercoiled plasmid DNA (pBR 322) confirmed the generation of OH or OH-like radicals during high-intensity excitation of HP. A mechanism involving a multistep excitation of HP, followed by resonance energy transfer to H 2 O resulting in dissociation to yield OH and H atoms, is proposed. (author)

Weak carbonyl-methyl intermolecular interactions in acetone clusters explored by IR plus VUV spectroscopy

International Nuclear Information System (INIS)

Guan, Jiwen; Hu, Yongjun; Xie, Min; Bernstein, Elliot R.

2012-01-01

Highlights: ► The carbonyl overtone of acetone clusters is observed by IR-VUV spectroscopy. ► Acetone molecules in the dimer are stacked with an antiparallel way. ► The structure of the acetone trimer and the tetramer are the cyclic structures. ► The carbonyl groups would interact with the methyl groups in acetone clusters. ► These weak interactions are further confirmed by H/D substitution experiment. -- Abstract: Size-selected IR–VUV spectroscopy is employed to detect vibrational characteristics in the region 2850 ∼ 3550 cm −1 of neutral acetone and its clusters (CH 3 COCH 3 ) n (n = 1–4). Features around 3440 cm −1 in the spectra of acetone monomer and its clusters are assigned to the carbonyl stretch (CO) overtone. These features red-shift from 3455 to 3433 cm −1 as the size of the clusters increases from the monomer to the tetramer. Based on calculations, the experimental IR spectra in the C=O overtone region suggest that the dominant structures for the acetone trimer and tetramer should be cyclic in the supersonic expansion sample. This study also suggests that the carbonyl groups interact with the methyl groups in the acetone clusters. These weak interactions are further confirmed by the use of deuterium substitution.

Effect of high-intensity pulsed electric fields processing and conventional heat treatment on orange-carrot juice carotenoids.

Science.gov (United States)

Torregrosa, Francisco; Cortés, Clara; Esteve, María J; Frígola, Ana

2005-11-30

Liquid chromatography (LC) was the method of choice for quantification of carotenoids (including geometrical isomers) to evaluate the effects of high-intensity pulsed electric field (HIPEF), a nonthermal preservation method, with different parameters (electric field intensities and treatment times), on an orange-carrot juice mixture (80:20, v/v). In parallel, a conventional heat treatment (98 degrees C, 21 s) was applied to the juice. HIPEF processing generally caused a significant increase in the concentrations of the carotenoids identified as treatment time increased. HIPEF treatment at 25 and 30 kV/cm provided a vitamin A concentration higher than that found in the pasteurized juice.

Intense Pulsed Light (IPL) in Aesthetic Dermatology

Science.gov (United States)

Pytras, B.; Drozdowski, P.; Zub, K.

2011-08-01

Introduction. Newer and newer technologies have been widely developed in recent years due to increasing need for aesthetic medicine procedures. Less invasive methods of skin imperfection and time-related lesions removal, IPL (Intense Pulse Light) being one of them, are gaining more and more interest. The shorter the "downtime" for the patient is and the more efficient the procedure results, the more popular the method becomes. Materials and methods_Authors analyse the results of treatment of a 571 patients-group (501 women and 70 men) aged 5-72 years in the period: October 2006-August 2010. IPL™ Quantum (Lumenis Ltd.) device with 560 nm. cut-off filter was used. Results. The results were regarded as: very good, good or satisfying (%):Skin photoaging symptomes 37/40/23, Isolated facial dyschromia 30/55/25, Isolated facial erythema 62/34/4, Lower limbs teleangiectasia 12/36/52, Keratosis solaris on hands 100/-/-. Approximately half of the patients developed transitory erythema and 25%- transitory, mild, circumscribed oedema. Following undesirable effects were noted: skin thermal irritation (6,1% of the patients) and skin hypopigmentation (2% of the patients). Discussion. Results and post-treatment management proposed by authors are similar to those reported by other authors. Conclusions. Treatment results of the 571-patients group prove IPL to be a very efficient method of non-ablative skin rejuvenation. It turned out effective also in lower limbs teleangiectasia treatment. It presents low risk of transitory and mild side effects. Futhermore, with short or no downtime, it is well-tolerated by the patients.

Multifunctional pulse generator for high-intensity focused ultrasound system

Science.gov (United States)

Tamano, Satoshi; Yoshizawa, Shin; Umemura, Shin-Ichiro

2017-07-01

High-intensity focused ultrasound (HIFU) can achieve high spatial resolution for the treatment of diseases. A major technical challenge in implementing a HIFU therapeutic system is to generate high-voltage high-current signals for effectively exciting a multichannel HIFU transducer at high efficiencies. In this paper, we present the development of a multifunctional multichannel generator/driver. The generator can produce a long burst as well as an extremely high-voltage short pulse of pseudosinusoidal waves (trigger HIFU) and second-harmonic superimposed waves for HIFU transmission. The transmission timing, waveform, and frequency can be controlled using a field-programmable gate array (FPGA) via a universal serial bus (USB) microcontroller. The hardware is implemented in a compact printed circuit board. The test results of trigger HIFU reveal that the power consumption and the temperature rise of metal-oxide semiconductor field-effect transistors were reduced by 19.9% and 38.2 °C, respectively, from the previous design. The highly flexible performance of the novel generator/driver is demonstrated in the generation of second-harmonic superimposed waves, which is useful for cavitation-enhanced HIFU treatment, although the previous design exhibited difficulty in generating it.

Magnet power supply control of the NSLS VUV and x-ray storage rings transfer lines

International Nuclear Information System (INIS)

Klein, J.D.; Ramamoorthy, S.; Singh, O.; Smith, J.D.

1985-01-01

The transfer lines for NSLS VUV and x-ray storage rings have been split. New power supplies have been incorporated with existing ones. The existing microprocessor system has been upgraded in order to control the additional functions. This system expands the input/output port of the microprocessor to an addressable serial/parallel link to each magnet power supply. The implementation of this system will be discussed

Self-compression of intense short laser pulses in relativistic magnetized plasma

Energy Technology Data Exchange (ETDEWEB)

Olumi, M.; Maraghechi, B., E-mail: behrouz@aut.ac.ir [Department of Physics, Amirkabir University of Technology, Post code 15916-34311 Tehran (Iran, Islamic Republic of)

2014-11-15

The compression of a relativistic Gaussian laser pulse in a magnetized plasma is investigated. By considering relativistic nonlinearity and using non-linear Schrödinger equation with paraxial approximation, a second-order differential equation is obtained for the pulse width parameter (in time) to demonstrate the longitudinal pulse compression. The compression of laser pulse in a magnetized plasma can be observed by the numerical solution of the equation for the pulse width parameter. The effects of magnetic field and chirping are investigated. It is shown that in the presence of magnetic field and negative initial chirp, compression of pulse is significantly enhanced.

Adhesion characteristics of VO2 ink film sintered by intense pulsed light for smart window

Science.gov (United States)

Youn, Ji Won; Lee, Seok-Jae; Kim, Kwang-Seok; Kim, Dae Up

2018-05-01

Progress in the development of energy-efficient coatings on glass has led to the research of smart windows that can modulate solar energy in response to an external stimulus like light, heat, or electricity. Thermochromic smart windows have attracted great interest because they provide highly visible transparency and intelligently controllable solar heat. VO2 has been widely used as coating material for thermochromism owing to its reversible metal-to-insulator transition near room temperature. However, unstable crystalline phases and expensive fabrication processes of VO2 films limit their facile application in smart windows. To overcome these restrictions, we manufactured nanoinks based on VO2 nanoparticles and fabricated films using spin coating and intense pulsed light (IPL) sintering on a quartz substrate. We examined adhesion between the VO2 nanoink films and the quartz substrate by varying the applied voltages and the number of pulses. The average adhesion of thin films increased to 83 and 108 N/m as the applied voltage during IPL sintering increased from 1400 to 2000 V. By increasing the number of pulses from 5 to 20, the adhesive strength increased from 83 to 94 N/m at 1400 V, and decreased from 108 to 96 N/m at 2000 V voltage.

Development and performance test of picosecond pulse x-ray excited streak camera system for scintillator characterization

International Nuclear Information System (INIS)

Yanagida, Takayuki; Fujimoto, Yutaka; Yoshikawa, Akira

2010-01-01

To observe time and wavelength-resolved scintillation events, picosecond pulse X-ray excited streak camera system is developed. The wavelength range spreads from vacuum ultraviolet (VUV) to near infrared region (110-900 nm) and the instrumental response function is around 80 ps. This work describes the principle of the newly developed instrument and the first performance test using BaF 2 single crystal scintillator. Core valence luminescence of BaF 2 peaking around 190 and 220 nm is clearly detected by our system, and the decay time turned out to be of 0.7 ns. These results are consistent with literature and confirm that our system properly works. (author)

Data acquisition system for the neutron scattering instruments at the intense pulsed neutron source

International Nuclear Information System (INIS)

Crawford, R.K.; Daly, R.T.; Haumann, J.R.; Hitterman, R.L.; Morgan, C.B.; Ostrowski, G.E.; Worlton, T.G.

1981-01-01

The Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory is a major new user-oriented facility which is now coming on line for basic research in neutron scattering and neutron radiation damage. This paper describes the data-acquisition system which will handle data acquisition and instrument control for the time-of-flight neutron-scattering instruments at IPNS. This discussion covers the scientific and operational requirements for this system, and the system architecture that was chosen to satisfy these requirements. It also provides an overview of the current system implementation including brief descriptions of the hardware and software which have been developed

Study of intense pulse irradiation effects on silicon targets considered as ground matter for optical detectors; Etude des effets d`irradiations pulsees intenses sur des cibles de silicium considere en tant que materiau de base pour detecteurs optiques

Energy Technology Data Exchange (ETDEWEB)

Muller, O

1994-12-01

This study aim was centered on morphological and structural alterations induced by laser irradiation on silicon targets considered as ground matter for optical detectors. First we recalled the main high light intensity effects on the condensed matter. Then we presented the experimental aspects. The experimental studies were achieved on two sample types: SiO{sub 2}/Si and Si. Two topics were studied: the defect chronology according to wavelength and pulse length, and the crystalline quality as well as the structure defects of irradiated zones by Raman spectroscopy. Finally, irradiation of Si targets by intense pulsed beams may lead to material fusion. This phenomenon is particularly easy when the material is absorbent, when the pulse is short and when the material is superficially oxidized. (MML). 204 refs., 93 figs., 21 tabs., 1 appendix.

Modelling of diffusion in presurface silicon layer under the action of pulsed high-intensity ion beam

International Nuclear Information System (INIS)

Aktaev, N.E.; Remnev, G.E.

2015-01-01

The influence of the pulsed high-intensity ion beam on the silicon is studied by use the developed theoretical model. The input parameters of the model were the settings of the experimental setup of the TEMP-4. It is shown, that at the short-pulsed implantation regime of the TEMP-4 the silicon surface does not melt. However, the regime leads to the high temperature gradient which promotes the diffusion process from the surface into the depth the silicon simple. The diffused particles are the carbon atoms adsorbed on the silicon surface by the various cases. Thus, it is shown that the carbon atom diffused from the surface make the main contribution to the forming of the concentration profile. The concentration of the implanted carbon ions less more than tree orders compared with the concentration of the diffused carbon atoms. (authors)

Comparison of different undulator schemes with superimposed alternating gradients for the VUV-FEL at the TESLA Test Facility

Energy Technology Data Exchange (ETDEWEB)

Pflueger, J.; Nikitina, Y.M. [DESY/HASYLAB, Hamburg (Germany)

1995-12-31

For the VUV-FEL at the TESLA Test Facility an undulator with a total length of 30 m is needed. In this study three different approaches to realize an undulator with a sinusoidal plus a superimposed quadrupolar field were studied with the 3D code MAFIA.

Fabrication of Elemental Copper by Intense Pulsed Light Processing of a Copper Nitrate Hydroxide Ink.

Science.gov (United States)

Draper, Gabriel L; Dharmadasa, Ruvini; Staats, Meghan E; Lavery, Brandon W; Druffel, Thad

2015-08-05

Printed electronics and renewable energy technologies have shown a growing demand for scalable copper and copper precursor inks. An alternative copper precursor ink of copper nitrate hydroxide, Cu2(OH)3NO3, was aqueously synthesized under ambient conditions with copper nitrate and potassium hydroxide reagents. Films were deposited by screen-printing and subsequently processed with intense pulsed light. The Cu2(OH)3NO3 quickly transformed in less than 100 s using 40 (2 ms, 12.8 J cm(-2)) pulses into CuO. At higher energy densities, the sintering improved the bulk film quality. The direct formation of Cu from the Cu2(OH)3NO3 requires a reducing agent; therefore, fructose and glucose were added to the inks. Rather than oxidizing, the thermal decomposition of the sugars led to a reducing environment and direct conversion of the films into elemental copper. The chemical and physical transformations were studied with XRD, SEM, FTIR and UV-vis.

Determination of ionization energies of CnN (n=4-12): Vacuum-ultraviolet (VUV) photoionization experiments and theoretical calculations

International Nuclear Information System (INIS)

Kostko, Oleg; Zhou, Jia; Sun, Bian Jian; Lie, Jie Shiuan; Chang, Agnes H.H.; Kaiser, Ralf I.; Ahmed, Musahid

2010-01-01

Results from single photon vacuum ultraviolet photoionization of astrophysically relevant CnN clusters, n = 4 - 12, in the photon energy range of 8.0 eV to 12.8 eV are presented. The experimental photoionization efficiency curves, combined with electronic structure calculations, provide improved ionization energies of the CnN species. A search through numerous nitrogen-terminated CnN isomers for n=4-9 indicates that the linear isomer has the lowest energy, and therefore should be the most abundant isomer in the molecular beam. Comparison with calculated results also shed light on the energetics of the linear CnN clusters, particularly in the trends of the even-carbon and the odd-carbon series. These results can help guide the search of potential astronomical observations of these neutral molecules together with their cations in highly ionized regions or regions with a high UV/VUV photon flux (ranging from the visible to VUV with flux maxima in the Lyman-a region) in the interstellar medium.

Cryogenic readout for multiple VUV4 Multi-Pixel Photon Counters in liquid xenon

Science.gov (United States)

Di Giovanni, A.

2018-03-01

This work concerned the preliminary tests and characterization of a cryogenic preamplifier board for an array made of 16 S13370-3050CN (VUV4 family) Multi-Pixel Photon Counters manufactured by Hamamatsu and operated at liquid xenon temperature. The proposed prototype is based on the use of the Analog Devices AD8011 current feedback operational amplifier. The detector allows for single photon detection, making this device a promising choice for the future generation of neutrino and dark matter detectors based on liquid xenon targets.

Imaging with Mass Spectrometry: A SIMS and VUV-Photoionization Study of Ion-Sputtered Atoms and Clusters from GaAs and Au

Energy Technology Data Exchange (ETDEWEB)

Takahashi, Lynelle; Zhou, Jia; Wilson, Kevin R.; Leone, Stephen R.; Ahmed, Musahid

2008-12-05

A new mass spectrometry surface imaging method is presented in which ion-sputtered neutrals are postionized by wavelength-tunable vacuum ultraviolet (VUV) light from a synchrotron source. Mass spectra and signal counts of the photoionized neutrals from GaAs (100) and Au are compared to those of the secondary ions. While clusters larger than dimers are more efficiently detected as secondary ions, certain species, such as As2, Au and Au2, are more efficiently detected through the neutral channel. Continuously tuning the photon wavelength allows photoionization efficiency (PIE) curves to be obtained for sputtered Asm (m=1,2) and Aun (n=1-4). From the observed ionization thresholds, sputtered neutral As and Au show no clear evidence of electronic excitation, while neutral clusters have photoionization onsets shifted to lower energies by ~;;0.3 eV. These shifts are attributed to unresolved vibrational and rotational excitations. High-spatial resolution chemical imaging with synchrotron VUV postionization is demonstrated at two different photon energies using a copper TEM grid embedded in indium. The resulting images are used to illustrate the use of tunable VUV light for verifying mass peak assignments by exploiting the unique wavelength-dependent PIE of each sputtered neutral species. This capability is valuable for identifying compounds when imaging chemically complex systems with mass spectrometry-based techniques.

Separation of VUV/UV photons and reactive particles in the effluent of a He/O{sub 2} atmospheric pressure plasma jet

Energy Technology Data Exchange (ETDEWEB)

Schneider, S; Benedikt, J [Coupled plasma-solid state systems, Fakultaet fuer Physik und Astronomie, Ruhr-Universitaet Bochum, Universitaetsstr. 150, 44780 Bochum (Germany); Lackmann, J-W; Narberhaus, F; Bandow, J E [Mikrobiologie, Fakultaet fuer Biologie, Ruhr-Universitaet Bochum, Universitaetsstr. 150, 44780 Bochum (Germany); Denis, B [Institute for Electrical Engineering and Plasma Technology, Ruhr-Universitaet Bochum, Universitaetsstr. 150, 44780 Bochum (Germany)

2011-07-27

Cold atmospheric pressure plasmas can be used for treatment of living tissues or for inactivation of bacteria or biological macromolecules. The treatment is usually characterized by a combined effect of UV and VUV radiation, reactive species and ions. This combination is usually beneficial for the effectiveness of the treatment but it makes the study of fundamental interaction mechanisms very difficult. Here we report on an effective separation of VUV/UV photons and heavy reactive species in the effluent of a microscale atmospheric pressure plasma jet ({mu}-APPJ). The separation is realized by an additional flow of helium gas under well-defined flow conditions, which deflects heavy particles in the effluent without affecting the VUV and UV photons. Both components of the effluent, the photons and the reactive species, can be used separately or in combination for sample treatment. The results of treatment of a model plasma polymer film and vegetative Bacillus subtilis and Escherichia coli cells are shown and discussed. A simple model of the He gas flow and reaction kinetics of oxygen atoms in the gas phase and at the surface is used to provide a better understanding of the processes in the plasma effluent. The new jet modification, called X-Jet for its appearance, will simplify the investigation of interaction mechanisms of atmospheric pressure plasmas with biological samples.

Classical-trajectory simulation of accelerating neutral atoms with polarized intense laser pulses

Science.gov (United States)

Xia, Q. Z.; Fu, L. B.; Liu, J.

2013-03-01

In the present paper, we perform the classical trajectory Monte Carlo simulation of the complex dynamics of accelerating neutral atoms with linearly or circularly polarized intense laser pulses. Our simulations involve the ion motion as well as the tunneling ionization and the scattering dynamics of valence electron in the combined Coulomb and electromagnetic fields, for both helium (He) and magnesium (Mg). We show that for He atoms, only linearly polarized lasers can effectively accelerate the atoms, while for Mg atoms, we find that both linearly and circularly polarized lasers can successively accelerate the atoms. The underlying mechanism is discussed and the subcycle dynamics of accelerating trajectories is investigated. We have compared our theoretical results with a recent experiment [Eichmann Nature (London)NATUAS0028-083610.1038/nature08481 461, 1261 (2009)].

Long-pulse operation of an intense negative ion source

Energy Technology Data Exchange (ETDEWEB)

Takeiri, Yasuhiko; Osakabe, Masaki; Tsumori, Katsuyoshi; Kaneko, Osamu; Oka, Yoshihide; Asano, Eiji; Kawamoto, Toshikazu; Akiyama, Ryuichi; Kuroda, Tsutomu [National Inst. for Fusion Science, Nagoya (Japan)

1997-02-01

In the National Institute for Fusion Science, as the heating system for the Large Helical Device (LHD), the negative ion NBI system of 20 MW incident power has been planned, and the development of a large current, large size negative ion source has been advanced. Based on the results obtained so far, the design of the LHD-NBI system was reconsidered, and the specification of the actual negative ion source was decided as 180 KeV-40A. This time, the grounding electrode with heightened heat removal capacity was made, and the long pulse operation was attempted, therefore, its results are reported. The structure of the external magnetic filter type large negative ion source used for the long pulse experiment is explained. In order to form the negative ion beam of long pulses, it is necessary to form stable are discharge plasma for long time, and variable resistors were attached to the output side of arc power sources of respective filament systems. By adjusting the resistors, uniform are discharge was able to be caused for longer than 10 s stably. The results of the long pulse experiment are reported. The dependence of the characteristics of negative ion beam on plasma electrode temperature was small, and the change of the characteristics of negative ion beam due to beam pulse width was not observed. (K.I.)

Conceptual design of a novel instrument for producing intense pulses of 10 ps X-rays for ultra-fast fluorescence measurements

Energy Technology Data Exchange (ETDEWEB)

Gruber, G.J.

1996-05-01

A novel bench-top device for producing intense, fast pulses of x-rays has been designed with 10 ps fwhm (full-width at half-maximum) x-ray pulse width, 120 keV maximum energy, 100 kHz repetition rate, and 1 A peak current onto the x-ray anode. The device includes three sections: (1) an electron gun that generates 5 ns wide pulses of 120 keV electrons at 100 kHz; (2) solenoidal magnetic lenses and deflection plates that focus the electrons onto an aperture plate and sweep the pulsed beam past the aperture, respectively; and (3) a tungsten anode onto which the post-aperture electrons are focused, producing pulses of x-rays. At a sweeping rate of 10{sup 13} V/s, the electron pulses and resulting x-ray pulses are reduced to about 10 ps. The design process used EGUN (an electron optics and gun design program) electron trajectory simulations, including calculation of important space charge effects. When built, this instrument will be used to excite new, fast, bright scintillator samples in crystal or powdered form, allowing fluorescent lifetimes and spectra to be measured with a microchannel PMT. The very narrow 10 ps x-ray pulse width is necessary for accurate measurements of the risetimes of very fast scintillators (e.g., BaF{sub 2}). In addition, the large x-ray flux (1 A peak current) is advantageous when using a reflection grating monochromator to measure decay times at different wavelengths.

Conceptual design of a novel instrument for producing intense pulses of 10 ps X-rays for ultra-fast fluorescence measurements

International Nuclear Information System (INIS)

Gruber, G.J.

1996-05-01

A novel bench-top device for producing intense, fast pulses of x-rays has been designed with 10 ps fwhm (full-width at half-maximum) x-ray pulse width, 120 keV maximum energy, 100 kHz repetition rate, and 1 A peak current onto the x-ray anode. The device includes three sections: (1) an electron gun that generates 5 ns wide pulses of 120 keV electrons at 100 kHz; (2) solenoidal magnetic lenses and deflection plates that focus the electrons onto an aperture plate and sweep the pulsed beam past the aperture, respectively; and (3) a tungsten anode onto which the post-aperture electrons are focused, producing pulses of x-rays. At a sweeping rate of 10 13 V/s, the electron pulses and resulting x-ray pulses are reduced to about 10 ps. The design process used EGUN (an electron optics and gun design program) electron trajectory simulations, including calculation of important space charge effects. When built, this instrument will be used to excite new, fast, bright scintillator samples in crystal or powdered form, allowing fluorescent lifetimes and spectra to be measured with a microchannel PMT. The very narrow 10 ps x-ray pulse width is necessary for accurate measurements of the risetimes of very fast scintillators (e.g., BaF 2 ). In addition, the large x-ray flux (1 A peak current) is advantageous when using a reflection grating monochromator to measure decay times at different wavelengths

Intense microwave pulse propagation through gas breakdown plasmas in a waveguide

International Nuclear Information System (INIS)

Byrne, D.P.

1986-01-01

High-power microwave pulse-compression techniques are used to generate 2.856 GHz pulses which are propagated in a TE 10 mode through a gas filled section of waveguide, where the pulses interact with self-generated gas-breakdown plasmas. Pulse envelopes transmitted through the plasmas, with duration varying from 2 ns to greater than 1 μs, and peak powers of a few kW to nearly 100 MW, are measured as a function of incident pulse and gas pressure for air, nitrogen, and helium. In addition, the spatial and temporal development of the optical radiation emitted by the breakdown plasmas are measured. For transmitted pulse durations ≥ 100 ns, good agreement is found with both theory and existing measurements. For transmitted pulse duration as short as 2 ns (less than 10 rf cycles), a two-dimensional model is used in which the electrons in the plasma are treated as a fluid whose interactions with the microwave pulse are governed by a self-consistent set of fluid equations and Maxwell's equations for the electromagnetic field. The predictions of this model for air are compared with the experimental results over a pressure range of 0.8 torr to 300 torr. Good agreement is obtained above about 1 torr pressure, demonstrating that microwave pulse propagation above the breakdown threshold can be accurately modeled on this time scale. 63 refs., 44 figs., 2 tabs

Simulation calculation for the energy deposition profile and the transmission fraction of intense pulsed electron beam at various incident angles

International Nuclear Information System (INIS)

Yang Hailiang; Qiu Aici; Zhang Jiasheng; Huang Jianjun; Sun Jianfeng

2002-01-01

The incident angles have a heavy effect on the intense pulsed electron beam energy deposition profile, energy deposition fraction and beam current transmission fraction in material. The author presents electron beam energy deposition profile and energy deposition fraction versus electron energy (0.5-2.0 MeV), at various incident angles for three aluminum targets of various thickness via theoretical calculation. The intense pulsed electron beam current transmission fractions versus electron energy (0.4-1.4 MeV) at various incident angles for three thickness of carbon targets were also theoretically calculated. The calculation results indicate that the deposition energy in unit mass of material surface layer increase with the rise of electron beam incident angle, and electron beam with low incident angle (closer to normal incident angle) penetrates deeper into the target material. The electron beams deposit more energy in unit mass of material surface layer at 60 degree-70 degree incident angle

Proton and electron impact on molecular and atomic oxygen: I. High resolution fluorescence spectra in the visible and VUV spectral range and emission cross-sections for dissociative ionisation and excitation of O2

International Nuclear Information System (INIS)

Wilhelmi, O.; Schartner, K.H.

2000-01-01

For pt.II see ibid., vol.11, p.45-58, 2000. Molecular oxygen O 2 was dissociated in collisions with protons and electrons in the intermediate velocity range (p + -energies: 17-800 keV, e - -energies: 0.2-2 keV). Fluorescence from excited atomic and singly ionised fragments and from singly ionised molecules was detected in the VUV and in the visible and near UV spectral range. Highly resolved spectra are presented for the VUV (46-131 nm) and the near UV/visible (340-605 nm) spectral range. Absolute emission cross-sections have been determined for dissociative ionisation and excitation leading to fluorescence in the VUV. Results are compared with published data. (orig.)

Evaluation of the Safety and Effectiveness of Intense Pulsed Light in the Treatment of Meibomian Gland Dysfunction

Directory of Open Access Journals (Sweden)

Xiaodan Jiang

2016-01-01

Full Text Available Purpose. This study aims to explore the safety and efficacy of a novel treatment-intense pulsed light (IPL in MGD eyes. Methods. This study is a prospective and open label study. Forty eyes of 40 MGD patients were recruited in the study and received 4 consecutive IPL treatments on day 1, day 15, day 45, and day 75. Ten ocular surface symptoms were evaluated with a subjective face score at every visit. Best spectacle corrected visual acuity, intraocular pressure (IOP, conjunctival injection, upper and lower tear meniscus height (TMH, tear break-up time (TBUT, corneal staining, lid margin and meibomian gland assessments, and meibography were also recorded at every visit, as well as the adverse effects on the eye and ocular surface. Results. Significant improvements were observed in single and total ocular surface symptom scores, TBUT, and conjunctival injection at all the visits after the initial IPL treatment (P<0.05. Compared to baseline, the signs of eyelid margin, meibomian gland secretion quality, and expressibility were significantly improved at every visit after treatments. There was no regional and systemic threat observed in any patient. Conclusion. Intense pulsed light (IPL therapy is a safe and efficient treatment in relieving symptoms and signs of MGD eyes.

High power ultrashort pulse lasers

International Nuclear Information System (INIS)

Perry, M.D.

1994-01-01

Small scale terawatt and soon even petawatt (1000 terawatt) class laser systems are made possible by application of the chirped-pulse amplification technique to solid-state lasers combined with the availability of broad bandwidth materials. These lasers make possible a new class of high gradient accelerators based on the large electric fields associated with intense laser-plasma interactions or from the intense laser field directly. Here, we concentrate on the laser technology to produce these intense pulses. Application of the smallest of these systems to the production of high brightness electron sources is also introduced

Production and detection of axion-like particles at the VUV-FEL. Letter of intent

International Nuclear Information System (INIS)

Koetz, U.; Ringwald, A.; Tschentscher, T.

2006-06-01

Recently, the PVLAS collaboration has reported evidence for an anomalously large rotation of the polarization of light generated in vacuum in the presence of a transverse magnetic field. This may be explained through the production of a new light spin-zero particle coupled to two photons. In this Letter of Intent, we propose to test this hypothesis by setting up a photon regeneration experiment which exploits the photon beam of the Vacuum-UltraViolet Free-Electron Laser VUV-FEL, sent along the transverse magnetic field of a linear arrangement of dipole magnets of size B L ∼ 30 Tm. The high photon energies available at the VUV-FEL increase substantially the expected photon regeneration rate in the mass range implied by the PVLAS anomaly, in comparison to the rate expected at visible lasers of similar power. We find that the particle interpretation of the PVLAS result can be tested within a short running period. The pseudoscalar vs. scalar nature can be determined by varying the direction of the magnetic field with respect to the laser polarization. The mass of the particle can be measured by running at different photon energies. The proposed experiment offers a window of opportunity for a firm establishment or exclusion of the particle interpretation of the PVLAS anomaly before other experiments can compete. (Orig.)

Effect of counter electric field during the irradiation of pulsed x-ray on the after-pulses of GM counter

International Nuclear Information System (INIS)

Igarashi, Ryuji; Narita, Yuichi; Ozawa, Yasutomo.

1979-01-01

The authors once made it clear by using pulsed radiation that the number of spurious discharge generation in organic gas-quenching type GM counters depends on the intensity of incident radiation. This spurious discharge is peculiar to the organic gas-quenching type GM counters, which the authors named after-pulses. The present study has been carried out to find the experimental conditions to verify the delayed generation mechanism of such after-pulses in bipolar GM tubes and the conditions to give the maximum number of after-pulses generation. For this purpose, a large low electric field region, whose field intensity is variable, should be provided in the tubes. Since it has been generally impossible in the bipolar GM tubes, the provision of that region transiently has been tried. The effect of the intensity of electric field in GM tubes during irradiation on the generation of after-pulses has been investigated by changing radiation intensity, anode voltage, and irradiated position. Consideration of the results has revealed that the number of after-pulse generation can be increased by forming transient low electric field region in the bipolar GM counters of organic gas-quenching type. It was the new knowledge that the transient anode voltage to maximize the after-pulse generating factor was several tens of negative voltage even if the conditions were varied. It seems that this fact depends upon the voltage giving the conditions to maximize the probability of forming after-pulse factors. (Wakatsuki, Y.)

Hot-electron surface retention in intense short-pulse laser-matter interactions.

Science.gov (United States)

Mason, R J; Dodd, E S; Albright, B J

2005-07-01

Implicit hybrid plasma simulations predict that a significant fraction of the energy deposited into hot electrons can be retained near the surface of targets with steep density gradients illuminated by intense short-pulse lasers. This retention derives from the lateral transport of heated electrons randomly emitted in the presence of spontaneous magnetic fields arising near the laser spot, from geometric effects associated with a small hot-electron source, and from E fields arising in reaction to the ponderomotive force. Below the laser spot hot electrons are axially focused into a target by the B fields, and can filament in moderate Z targets by resistive Weibel-like instability, if the effective background electron temperature remains sufficiently low. Carefully engineered use of such retention in conjunction with ponderomotive density profile steepening could result in a reduced hot-electron range that aids fast ignition. Alternatively, such retention may disturb a deeper deposition needed for efficient radiography and backside fast ion generation.

Complex tibial fracture outcomes following treatment with low-intensity pulsed ultrasound.

Science.gov (United States)

Leung, Kwok-Sui; Lee, Wing-Sze; Tsui, Hon-For; Liu, Paul Po-Lung; Cheung, Wing-Hoi

2004-03-01

A clinical study was conducted to investigate the effect of low-intensity pulsed ultrasound (US) stimulation (LIPUS) on the healing of complex tibial fractures. Thirty complex tibial fractures were randomly assigned to the treatment with LIPUS (n = 16) or by a dummy machine (sham-exposed: n = 14). The fractures were immobilized by either internal or external fixations according to the clinical indications. LIPUS was given 20 min/day for 90 days. Fracture healing was monitored by clinical, radiological, densitometric and biochemical assessments. The LIPUS-treated group showed statistically significantly better healing, as demonstrated by all assessments. Complications were minimal in the LIPUS group. There were two cases of delayed union, with one in each group. There were two cases of infection in the control group. The delayed-union cases were subsequently treated by LIPUS and the infection cases were treated with standard protocol. Fracture healing in these patients was again treated by LIPUS.

Time dependence of X-ray polarizability of a crystal induced by an intense femtosecond X-ray pulse

Directory of Open Access Journals (Sweden)

A. Leonov

2014-11-01

Full Text Available The time evolution of the electron density and the resulting time dependence of Fourier components of the X-ray polarizability of a crystal irradiated by highly intense femtosecond pulses of an X-ray free-electron laser (XFEL is investigated theoretically on the basis of rate equations for bound electrons and the Boltzmann equation for the kinetics of the unbound electron gas. The photoionization, Auger process, electron-impact ionization, electron–electron scattering and three-body recombination have been implemented in the system of rate equations. An algorithm for the numerical solution of the rate equations was simplified by incorporating analytical expressions for the cross sections of all the electron configurations in ions within the framework of the effective charge model. Using this approach, the time dependence of the inner shell populations during the time of XFEL pulse propagation through the crystal was evaluated for photon energies between 4 and 12 keV and a pulse width of 40 fs considering a flux of 1012 photons pulse−1 (focusing on a spot size of ∼1 µm. This flux corresponds to a fluence ranging between 0.8 and 2.4 mJ µm−2. The time evolution of the X-ray polarizability caused by the change of the atomic scattering factor during the pulse propagation is numerically analyzed for the case of a silicon crystal. The time-integrated polarizability drops dramatically if the fluence of the X-ray pulse exceeds 1.6 mJ µm−2.

Effects of low-intensity pulsed ultrasound on injured skeletal muscle

Directory of Open Access Journals (Sweden)

Camila S. Montalti

2013-08-01

Full Text Available BACKGROUND: Low-intensity pulsed ultrasound (LIPUS has been shown to stimulate tissue metabolism and accelerate muscle healing. However, the optimal parameters in the use of LIPUS are still not clear. OBJECTIVE: The aim of this study was to analyze the effects of LIPUS on muscle healing in rats subjected to a cryolesion. METHOD: Twenty rats were divided into the following groups: an injured control group (CG and an injured treated group (TG. Both groups were divided into 2 sub-groups (n=5 each that were sacrificed 7 and 13 days post-surgery. Treatments were started 24 hours after the surgical procedure and consisted of 3 or 6 sessions. After euthanasia, the muscles were submitted to standard histological procedures. RESULTS: Qualitative analyses were based on morphological assessments of the muscle. The histopathological analysis on day 7 revealed that the muscles in the CG and the TG presented an intense inflammatory infiltrate, a large necrotic area and a disorganized tissue structure. After 13 days, both the CG and the TG had granulation tissue and newly formed fibers. The TG presented a more organized tissue structure. The quantitative analysis of collagen indicated similar findings among the groups, although the qualitative analysis revealed a better organization of collagen fibers in the TG at 13 days. The immunohistochemical analysis indicated that, at both time points, the expression of cyclooxygenase-2 was upregulated in the TG compared to the CG. CONCLUSIONS: LIPUS used as a treatment for muscle injury induced a more organized tissue structure at the site of the injury and stimulated the expression of COX-2 and the formation of new muscle fibers.

Nonlinear evolutions of an ultra-intense ultra-short laser pulse in a rarefied plasma through a new quasi-static theory

Science.gov (United States)

Yazdanpanah, J.

2018-02-01

In this paper, we present a new description of self-consistent wake excitation by an intense short laser pulse, based on applying the quasi-static approximation (slow variations of the pulse-envelope) in the instantaneous Lorentz-boosted pulse co-moving frame (PCMF), and best verify our results through comparison with particle-in-cell simulations. According to this theory, the plasma motion can be treated perturbatively in the PCMF due to its high initial-velocity and produces a quasi-static wakefield in this frame. The pulse envelope, on the other hand, is governed by a form of the Schrödinger equation in the PCMF, in which the wakefield acts as an effective potential. In this context, pulse evolutions are characterized by local conservation laws resulted from this equation and subjected to Lorentz transformation into the laboratory frame. Using these conservation laws, precise formulas are obtained for spatiotemporal pulse evolutions and related wakefield variations at initial stages, and new equations are derived for instantaneous group velocity and carrier frequency. In addition, based on properties of the Schrödinger equation, spectral-evolutions of the pulse are described and the emergence of an anomalous dispersion branch with linear relation ω ≈ ck (c is the light speed) is predicted. Our results are carefully discussed versus previous publications and the significance of our approach is described by showing almost all suggestive definitions of group-velocity based on energy arguments fail to reproduce our formula and correctly describe the instantaneous pulse-velocity.

Moderate and high intensity pulsed electric fields

NARCIS (Netherlands)

Timmermans, Rian Adriana Hendrika

2018-01-01

Pulsed Electric Field (PEF) processing has gained a lot of interest the last decades as mild processing technology as alternative to thermal pasteurisation, and is suitable for preservation of liquid food products such as fruit juices. PEF conditions typically applied at industrial scale for

Relativistic acceleration and retardation effects on photoemission of intense electron short pulses, in RF-FEL photoinjectors

International Nuclear Information System (INIS)

Dolique, J.M.; Coacolo, M.

1991-01-01

In high-power free electron lasers, self-field effects in the electron beam are often the most important phenomenon on which the beam quality depends. These effects are generally conceived as space-charge effects, and described by a Poisson equation in a beam frame. In RF-FEL photoinjectors, the electrons of the intense short pulse produced by laser irradiation are submitted, just after their photoemission, to such a strong acceleration that relativistic acceleration and retardation effects are discussed, from the rigorous calculation of the Lienard-Wiechert velocity- and acceleration electric and magnetic fields, as a function of RF-electric field and beam parameters. The beam pulse is assumed to be axisymmetric, with a constant photoemitted current density. Consequences for the maximum current density that can be extracted are considered (the 'self-field limit,' a name more appropriate than 'space-charge limit' for the present conditions where electro-dynamic phenomena play an important role)

VUV spectroscopy of pure LiCaAlF6 crystals

International Nuclear Information System (INIS)

Kirm, M.; True, M.; Vielhauer, S.; Zimmerer, G.; Shiran, N.V.; Shpinkov, I.; Spassky, D.; Shimamura, K.; Ichinose, N.

2005-01-01

Reflection, excitation and luminescence spectra of as-grown and X-ray irradiated high-purity LiCaAlF 6 crystals were studied in the temperature range of 10-300 K using synchrotron radiation in VUV. The intrinsic luminescence of samples at 10 K consists of a non-elementary broad band with maximum at 4.4 eV under excitation at 11.45 eV. It is ascribed to the radiative decay of self-trapped excitons. The energy gap is estimated to be 12.65 eV in LiCaAlF 6 . Under interband excitation a red shift of luminescence was observed. The electron-hole recombination leads to the emission peaking at 3.7 eV. The excitation processes and origin of overlapping emissions of LiCaAlF 6 are discussed

Vacuum ultraviolet (VUV) absorption spectra of chromatin and its components

International Nuclear Information System (INIS)

Dodonova, N.Y.; Kiseleva, M.N.; Petrov, M.Y.; Tsyganenko, N.M.; Bubyakina, V.V.; Chikhirzhina, G.I.

1984-01-01

The electron absorption spectra of thin films of chromatin and chromatin components in the ultraviolet region (140-280 nm) were investigated. The absorption coefficients μ(lambda) of chromatin, nucleosomes with and without histone H1, total histones (TH), and DNA were compared. The spectra of nucleosomes differ from the sum-spectrum of DNA plus TH. The chromatin and nucleosome spectra are not similar in the spectral region of 190-160 nm. The lack of additivity of absorption coefficients at different wavelengths may be explained by different conformational changes of DNA, TH in nucleosomes and chromatin during the process of drying aqueous solutions for the preparation of thin films. The μ(lambda) values are useful for an estimate of the DNA and TH absorption in chromatin and nucleosomes in discussing UV and VUV irradiation damages. (Auth.)

Enhanced self-magnetic field by atomic polarization in partially stripped plasma produced by a short and intense laser pulse

International Nuclear Information System (INIS)

Hu Qianglin; Liu Shibing; Jiang, Y.J.; Zhang Jie

2005-01-01

The enhancement and redistribution of a self-generated quasistatic magnetic field, due to the presence of the polarization field induced by partially ionized atoms, are analytically revealed when a linearly polarized intense and short pulse laser propagates in a partially stripped plasma with higher density. In particular, the shorter wavelength of the laser pulse can evidently intensify the amplitude of the magnetic field. These enhancement and redistribution of the magnetic field are considered physically as a result of the competition of the electrostatic field (electron-ion separation) associated with the plasma wave, the atomic polarization field, and the pondoromotive potential associated with the laser field. This competition leads to the generation of a positive, large amplitude magnetic field in the zone of the pulse center, which forms a significant difference in partially and fully stripped plasmas. The numerical result shows further that the magnetic field is resonantly modulated by the plasma wave when the pulse length is the integer times the plasma wavelength. This apparently implies that the further enhancement and restructure of the large amplitude self-magnetic field can evidently impede the acceleration and stable transfer of the hot-electron beam

VUV Optics Development for the Elettra Storage Ring FEL

CERN Document Server

Guenster, Stefan

2004-01-01

Vacuum ultraviolet optical components for the storage ring FEL at Elettra are under continuous development in the European research consortium EUFELE. Target of the project is the progress to shorter lasing wavelengths in the VUV spectral range. The current status allows lasing with oxide mirror systems down to 190 nm. The main obstacles for the development of optical coatings for shorter wavelengths is the high energetic background of the synchrotron radiation impinging onto the front mirror in the laser cavity. Investigations in single layer systems and multilayer stacks of oxide or fluoride materials demonstrate that fluoride mirrors reach highest reflectivity values down to 140 nm, and oxide coatings possess a satisfactory resistance against the high energetic background irradiation. However, pure oxide multilayer stacks exhibit significant absorption below 190 nm and pure fluoride stacks suffer from strong degradation effects under synchrotron radiation. A solution could be hybrid systems, combining fluo...

Applicability of Pulse Pressure Variation during Unstable Hemodynamic Events in the Intensive Care Unit: A Five-Day Prospective Multicenter Study

Directory of Open Access Journals (Sweden)

Bertrand Delannoy

2016-01-01

Full Text Available Pulse pressure variation can predict fluid responsiveness in strict applicability conditions. The purpose of this study was to describe the clinical applicability of pulse pressure variation during episodes of patient hemodynamic instability in the intensive care unit. We conducted a five-day, seven-center prospective study that included patients presenting with an unstable hemodynamic event. The six predefined inclusion criteria for pulse pressure variation applicability were as follows: mechanical ventilation, tidal volume >7 mL/kg, sinus rhythm, no spontaneous breath, heart rate/respiratory rate ratio >3.6, absence of right ventricular dysfunction, or severe valvulopathy. Seventy-three patients presented at least one unstable hemodynamic event, with a total of 163 unstable hemodynamic events. The six predefined criteria for the applicability of pulse pressure variation were completely present in only 7% of these. This data indicates that PPV should only be used alongside a strong understanding of the relevant physiology and applicability criteria. Although these exclusion criteria appear to be profound, they likely represent an absolute contraindication of use for only a minority of critical care patients.

A VUV photoionization measurement and ab-initio calculation of the ionization energy of gas phase SiO2

Energy Technology Data Exchange (ETDEWEB)

Kostko, Oleg; Ahmed, Musahid; Metz, Ricardo B.

2008-12-05

In this work we report on the detection and vacuum-ultraviolet (VUV) photoionization of gas phase SiO2 generated in situ via laser ablation of silicon in a CO2 molecular beam. The resulting species are investigated by single photon ionization with tunable VUV synchrotron radiation and mass analyzed using reflectron mass spectrometry. Photoionization efficiency (PIE) curves are recorded for SiO and SiO2 and ionization energy estimates are revealed from such measurements. A state-to-state ionizationenergy of 12.60 (+-0.05) eV is recorded by fitting two prominent peaks in the PIE curve for the following process: 1SUM O-Si-O --> 2PRODg [O-Si-O]+. Electronic structure calculations aid in the interpretation of the photoionization process and allow for identification of the symmetric stretch of 2PRODg [O-Si-O]+ which is observed in the PIE spectrum to be 0.11 eV (890 cm-1) above the ground state of the cation and agrees with the 892 cm-1 symmetric stretch frequency calculated at the CCSD(T)/aug-cc-pVTZ level.

Computer modelling of a short-pulse excited dielectric barrier discharge xenon excimer lamp (lambda approx 172 nm)

CERN Document Server

Carman, R J

2003-01-01

A detailed rate-equation analysis has been used to simulate the plasma kinetics in a pulsed-excited dielectric barrier discharge in xenon, under operating conditions where the discharge structure is spatially homogeneous. The one-dimensional model, incorporating 14 species and 70 reaction processes, predicts results that are in good agreement with experimental measurements of the electrical characteristics, and optical (vacuum-ultraviolet (VUV) and visible) pulse shapes. The model reveals that electrical breakdown of the discharge gap occurs via a fast-moving ionization/excitation wavefront that starts close to the anode dielectric and propagates towards the cathode at approx 3x10 sup 5 m s sup - sup 1. The wavefront appears as a result of successive avalanches of electrons that propagate across the discharge gap after release from the cathode dielectric. During breakdown, the mean electron energy in the bulk plasma is close to optimum for preferential excitation of the Xe* 1s sub 4 sub , sub 5 states that fe...

MR-Guided Pulsed High-Intensity Focused Ultrasound Enhancement of Gene Therapy Combined With Androgen Deprivation and Radiotherapy for Prostate Cancer Treatment

Science.gov (United States)

2009-09-01

ultrasound . J. Acoust. Soc.Am. 72 1926-1932, (1982) (7) Neppiras E A. Acoustic cavitation . Physics reports 61(3): 159-251, (1980) (8) ter Haar G R, Daniels...Guided Pulsed High-Intensity Focused Ultrasound Enhancement of 5b. GRANT NUMBER W81XWH-08-1-0469 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT...failing to This work is aimed to study MR guided high intensity focused ultrasound (MRgHIFU) enhancement of gene therapy for Prostate Cancer. The

Quantum key distribution with an efficient countermeasure against correlated intensity fluctuations in optical pulses

Science.gov (United States)

Yoshino, Ken-ichiro; Fujiwara, Mikio; Nakata, Kensuke; Sumiya, Tatsuya; Sasaki, Toshihiko; Takeoka, Masahiro; Sasaki, Masahide; Tajima, Akio; Koashi, Masato; Tomita, Akihisa

2018-03-01

Quantum key distribution (QKD) allows two distant parties to share secret keys with the proven security even in the presence of an eavesdropper with unbounded computational power. Recently, GHz-clock decoy QKD systems have been realized by employing ultrafast optical communication devices. However, security loopholes of high-speed systems have not been fully explored yet. Here we point out a security loophole at the transmitter of the GHz-clock QKD, which is a common problem in high-speed QKD systems using practical band-width limited devices. We experimentally observe the inter-pulse intensity correlation and modulation pattern-dependent intensity deviation in a practical high-speed QKD system. Such correlation violates the assumption of most security theories. We also provide its countermeasure which does not require significant changes of hardware and can generate keys secure over 100 km fiber transmission. Our countermeasure is simple, effective and applicable to wide range of high-speed QKD systems, and thus paves the way to realize ultrafast and security-certified commercial QKD systems.

Applications of pulsed intense relativistic electron beam to aquatic conservation

International Nuclear Information System (INIS)

Kikuchi, Takashi; Kondo, Hironobu; Sasaki, Toru; Harada, Nob.; Moriwaki, Hiroshi; Imada, Go

2012-01-01

In this study, we propose aquatic conservations by using a pulsed intense relativistic electron beam (PIREB). Treatments of introduced species and toxics azo dyes by irradiating PIREB are investigated in this report. Zooplankton contained in water have been inactivated by irradiation of PIREB. A treatment chamber is filled with a solution of 3-wt% salt in water containing Artemia larvae as zooplankton samples, and is irradiated using the PIREB (2 MeV, 0.4 kA, 140 ns). We found that up to 24% of the Artemia are inactivated by firing 10 shots of PIREB irradiation. It is found that pH changes did not affect to inactivate the Artemia larvae during the time scale of PIREB irradiation. The reaction of congo red, a well-known toxic azo dye, occurred after irradiation by PIREB. An aquation of congo red was irradiated by PIREB (2 MeV, 0.36 kA, 140 ns). After PIREB irradiation, the solution was measured by electrospray ionization-mass spectrometry and liquid chromatography/mass spectrometry. It was found that congo red underwent a reaction (77% conversion after five shots of PIREB irradiation) and the hydroxylated compounds of the dye were observed as reaction products. (author)

Effects of low-intensity pulsed ultrasound on new trabecular bone during bone-tendon junction healing in a rabbit model: a synchrotron radiation micro-CT study.

Directory of Open Access Journals (Sweden)

Hongbin Lu

Full Text Available This study was designed to evaluate the effects of low-intensity pulsed ultrasound on bone regeneration during the bone-tendon junction healing process and to explore the application of synchrotron radiation micro computed tomography in three dimensional visualization of the bone-tendon junction to evaluate the microarchitecture of new trabecular bone. Twenty four mature New Zealand rabbits underwent partial patellectomy to establish a bone-tendon junction injury model at the patella-patellar tendon complex. Animals were then divided into low-intensity pulsed ultrasound treatment (20 min/day, 7 times/week and placebo control groups, and were euthanized at week 8 and 16 postoperatively (n = 6 for each group and time point. The patella-patellar tendon specimens were harvested for radiographic, histological and synchrotron radiation micro computed tomography detection. The area of the newly formed bone in the ultrasound group was significantly greater than that of control group at postoperative week 8 and 16. The high resolution three dimensional visualization images of the bone-tendon junction were acquired by synchrotron radiation micro computed tomography. Low-intensity pulsed ultrasound treatment promoted dense and irregular woven bone formation at week 8 with greater bone volume fraction, number and thickness of new trabecular bone but with lower separation. At week 16, ultrasound group specimens contained mature lamellar bone with higher bone volume fraction and thicker trabeculae than that of control group; however, there was no significant difference in separation and number of the new trabecular bone. This study confirms that low-intensity pulsed ultrasound treatment is able to promote bone formation and remodeling of new trabecular bone during the bone-tendon junction healing process in a rabbit model, and the synchrotron radiation micro computed tomography could be applied for three dimensional visualization to quantitatively evaluate

Higher-order-mode (HOM) power in elliptical superconducting cavities for intense pulsed proton accelerators

CERN Document Server

Sang Ho Kim; Dong O Jeon; Sundeli, R

2002-01-01

In linacs for intense pulsed proton accelerators, the beam has a multiple time-structure, and each beam time-structure generates resonance. When a higher-order mode (HOM) is near these resonance frequencies, the induced voltage could be large and accordingly the resulting HOM power, too. In order to understand the effects of a complex beam time-structure on the mode excitations and the resulting HOM powers in elliptical superconducting cavities, analytic expressions are developed, with which the beam-induced voltage and corresponding power are explored, taking into account the properties of HOM frequency behavior in elliptical superconducting cavities. The results and understandings from this analysis are presented with the beam parameters of the Spallation Neutron Source (SNS) superconducting linac.

Virtual-anode formation by an intense pulsed ion beam incident upon a magnetic barrier

International Nuclear Information System (INIS)

Robertson, S.; Wessel, F.

1980-01-01

An intense, pulsed, initially space-charge-neutral ion beam (100 kV, 1 kA, 600 nsec) has been propagated into a transversely oriented magnetic barrier. When the magnetic field is adjusted so that (rho/sub i/rho/sub e/)/sup 1/2/ very-much-less-than a < rho/sub i/, a virtual anode is formed whose potential oscillates at approx.ω/sub p/i about a value near the ion accelerating potential, where a is the transverse beam dimension, ω/sub tsp/i is the ion plasma frequency, and rho/sub e/ and rho/sub i/ are the electron and ion gyroradii. This behavior is similar to that predicted by Poukey and Rostoker for virtual cathodes

Low-intensity pulsed ultrasound (LIPUS) stimulates mineralization of MC3T3-E1 cells through calcium and phosphate uptake.

Science.gov (United States)

Tassinary, João Alberto Fioravante; Lunardelli, Adroaldo; Basso, Bruno de Souza; Dias, Henrique Bregolin; Catarina, Anderson Velasque; Stülp, Simone; Haute, Gabriela Viegas; Martha, Bianca Andrade; Melo, Denizar Alberto da Silva; Nunes, Fernanda Bordignon; Donadio, Márcio Vinícius Fagundes; Oliveira, Jarbas Rodrigues de

2018-03-01

The present study aimed to evaluate the effect of low-intensity pulsed ultrasound (LIPUS) on pre-osteoblast mineralization using in vitro bioassays. Pre-osteoblastic MC3T3-E1 cells were exposed to LIPUS at 1 MHz frequency, 0.2 W/cm 2 intensity and 20% duty cycle for 30 min. The analyses were carried out up to 336 h (14 days) after exposure. The concentration of collagen, phosphate, alkaline phosphatase, calcium and transforming growth factor beta 1 (TGF-β1) in cell supernatant and the presence of calcium deposits in the cells were analyzed. Our results showed that LIPUS promotes mineralized nodules formation. Collagen, phosphate, and calcium levels were decreased in cell supernatant at 192 h after LIPUS exposure. However, alkaline phosphatase and TGF-β1 concentrations remained unchanged. Therapeutic pulsed ultrasound is capable of stimulating differentiation and mineralization of pre-osteoblastic MC3T3-E1 cells by calcium and phosphate uptake with consequent hydroxyapatite formation. Copyright © 2017 Elsevier B.V. All rights reserved.

Formation and fragmentation of quadruply charged molecular ions by intense femtosecond laser pulses.

Science.gov (United States)

Yatsuhashi, Tomoyuki; Nakashima, Nobuaki