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Sample records for high-power pulsed sputtering

  1. Plasma regimes in high power pulsed magnetron sputtering

    NASA Astrophysics Data System (ADS)

    de Los Arcos, Teresa

    2013-09-01

    High Power Pulsed Magnetron Sputtering (HPPMS) is a relatively recent variation of magnetron sputtering where high power is applied to the magnetron in short pulses. The result is the formation of dense transient plasmas with a high fraction of ionized species, ideally leading to better control of film growth through substrate bias. However, the broad range of experimental conditions accessible in pulsed discharges results in bewildering variations in current and voltage pulse shapes, pulse power densities, etc, which represent different discharge behaviors, making it difficult to identify relevant deposition conditions. The complexity of the plasma dynamics is evident. Within each pulse, plasma characteristics such as plasma composition, density, gas rarefaction, spatial distribution, degree of self-sputtering, etc. vary with time. A recent development has been the discovery that the plasma emission can self-organize into well-defined regions of high and low plasma emissivity above the racetrack (spokes), which rotate in the direction given by the E ×B drift and that significantly influence the transport mechanisms in HPPMS. One seemingly universal characteristic of HPPMS plasmas is the existence of well defined plasma regimes for different power ranges. These regimes are clearly differentiated in terms of plasma conductivity, plasma composition and spatial plasma self-organization. We will discuss the global characteristics of these regimes in terms of current-voltage characteristics, energy-resolved QMS and OES analysis, and fast imaging. In particular we will discuss how the reorganization of the plasma emission into spokes is associated only to specific regimes of high plasma conductivity. We will also briefly discuss the role of the target in shaping the characteristics of the HPPMS plasma, since sputtering is a surface-driven process. This work was supported by the Deutsche Forschungsgemeinschaft (DFG) within the framework of the SFB-TR87.

  2. High power pulsed magnetron sputtering: A method to increase deposition rate

    SciTech Connect

    Raman, Priya McLain, Jake; Ruzic, David N; Shchelkanov, Ivan A.

    2015-05-15

    High power pulsed magnetron sputtering (HPPMS) is a state-of-the-art physical vapor deposition technique with several industrial applications. One of the main disadvantages of this process is its low deposition rate. In this work, the authors report a new magnetic field configuration, which produces deposition rates twice that of conventional magnetron's dipole magnetic field configuration. Three different magnet pack configurations are discussed in this paper, and an optimized magnet pack configuration for HPPMS that leads to a higher deposition rate and nearly full-face target erosion is presented. The discussed magnetic field produced by a specially designed magnet assembly is of the same size as the conventional magnet assembly and requires no external fields. Comparison of deposition rates with different power supplies and the electron trapping efficiency in complex magnetic field arrangements are discussed.

  3. High power impulse magnetron sputtering discharge

    SciTech Connect

    Gudmundsson, J. T.; Brenning, N.; Lundin, D.; Helmersson, U.

    2012-05-15

    The high power impulse magnetron sputtering (HiPIMS) discharge is a recent addition to plasma based sputtering technology. In HiPIMS, high power is applied to the magnetron target in unipolar pulses at low duty cycle and low repetition frequency while keeping the average power about 2 orders of magnitude lower than the peak power. This results in a high plasma density, and high ionization fraction of the sputtered vapor, which allows better control of the film growth by controlling the energy and direction of the deposition species. This is a significant advantage over conventional dc magnetron sputtering where the sputtered vapor consists mainly of neutral species. The HiPIMS discharge is now an established ionized physical vapor deposition technique, which is easily scalable and has been successfully introduced into various industrial applications. The authors give an overview of the development of the HiPIMS discharge, and the underlying mechanisms that dictate the discharge properties. First, an introduction to the magnetron sputtering discharge and its various configurations and modifications is given. Then the development and properties of the high power pulsed power supply are discussed, followed by an overview of the measured plasma parameters in the HiPIMS discharge, the electron energy and density, the ion energy, ion flux and plasma composition, and a discussion on the deposition rate. Finally, some of the models that have been developed to gain understanding of the discharge processes are reviewed, including the phenomenological material pathway model, and the ionization region model.

  4. Influence of nitrogen admixture to argon on the ion energy distribution in reactive high power pulsed magnetron sputtering of chromium

    NASA Astrophysics Data System (ADS)

    Breilmann, W.; Maszl, C.; Hecimovic, A.; von Keudell, A.

    2017-04-01

    Reactive high power impulse magnetron sputtering (HiPIMS) of metals is of paramount importance for the deposition of various oxides, nitrides and carbides. The addition of a reactive gas such as nitrogen to an argon HiPIMS plasma with a metal target allows the formation of the corresponding metal nitride on the substrate. The addition of a reactive gas introduces new dynamics into the plasma process, such as hysteresis, target poisoning and the rarefaction of two different plasma gases. We investigate the dynamics for the deposition of chromium nitride by a reactive HiPIMS plasma using energy- and time-resolved ion mass spectrometry, fast camera measurements and temporal and spatially resolved optical emission spectroscopy. It is shown that the addition of nitrogen to the argon plasma gas significantly changes the appearance of the localized ionization zones, the so-called spokes, in HiPIMS plasmas. In addition, a very strong modulation of the metal ion flux within each HiPIMS pulse is observed, with the metal ion flux being strongly suppressed and the nitrogen molecular ion flux being strongly enhanced in the high current phase of the pulse. This behavior is explained by a stronger return effect of the sputtered metal ions in the dense plasma above the racetrack. This is best observed in a pure nitrogen plasma, because the ionization zones are mostly confined, implying a very high local plasma density and consequently also an efficient scattering process.

  5. Evidence for breathing modes in direct current, pulsed, and high power impulse magnetron sputtering plasmas

    SciTech Connect

    Yang, Yuchen; Zhou, Xue; Liu, Jason X.; Anders, André

    2016-01-18

    We present evidence for breathing modes in magnetron sputtering plasmas: periodic axial variations of plasma parameters with characteristic frequencies between 10 and 100 kHz. A set of azimuthally distributed probes shows synchronous oscillations of the floating potential. They appear most clearly when considering the intermediate current regime in which the direction of azimuthal spoke motion changes. Breathing oscillations were found to be superimposed on azimuthal spoke motion. Depending on pressure and current, one can also find a regime of chaotic fluctuations and one of stable discharges, the latter at high current. A pressure-current phase diagram for the different situations is proposed.

  6. Reactive high power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Gudmundsson, J. T.; Magnus, F.; Tryggvason, T. K.; Sveinsson, O. B.; Olafsson, S.

    2012-10-01

    Here we discuss reactive high power impulse magnetron sputtering sputtering (HiPIMS) [1] of Ti target in an Ar/N2 and Ar/O2 atmosphere. The discharge current waveform is highly dependent on both the pulse repetition frequency and discharge voltage. The discharge current increases with decreasing frequency or voltage. This we attribute to an increase in the secondary electron emission yield during the self-sputtering phase of the pulse, as nitride [2] or oxide [3] forms on the target. We also discuss the growth of TiN films on SiO2 at temperatures of 22-600 ^oC. The HiPIMS process produces denser films at lower growth temperature and the surface is much smoother and have a significantly lower resistivity than dc magnetron sputtered films on SiO2 at all growth temperatures due to reduced grain boundary scattering [4].[4pt] [1] J. T. Gudmundsson, N. Brenning, D. Lundin and U. Helmersson, J. Vac. Sci. Technol. A, 30 030801 (2012)[0pt] [2] F. Magnus, O. B. Sveinsson, S. Olafsson and J. T. Gudmundsson, J. Appl. Phys., 110 083306 (2011)[0pt] [3] F. Magnus, T. K. Tryggvason, S. Olafsson and J. T. Gudmundsson, J. Vac. Sci. Technol., submitted 2012[0pt] [4] F. Magnus, A. S. Ingason, S. Olafsson and J. T. Gudmundsson, IEEE Elec. Dev. Lett., accepted 2012

  7. HIGH POWER PULSED OSCILLATOR

    DOEpatents

    Singer, S.; Neher, L.K.

    1957-09-24

    A high powered, radio frequency pulse oscillator is described for generating trains of oscillations at the instant an input direct voltage is impressed, or immediately upon application of a light pulse. In one embodiment, the pulse oscillator comprises a photo-multiplier tube with the cathode connected to the first dynode by means of a resistor, and adjacent dynodes are connected to each other through adjustable resistors. The ohmage of the resistors progressively increases from a very low value for resistors adjacent the cathode to a high value adjacent the plate, the last dynode. Oscillation occurs with this circuit when a high negative voltage pulse is applied to the cathode and the photo cathode is bombarded. Another embodiment adds capacitors at the resistor connection points of the above circuit to increase the duration of the oscillator train.

  8. Influence of Ar/Kr ratio and pulse parameters in a Cr-N high power pulse magnetron sputtering process on plasma and coating properties

    SciTech Connect

    Bobzin, Kirsten; Bagcivan, Nazlim; Theiß, Sebastian; Trieschmann, Jan; Brugnara, Ricardo Henrique; Preissing, Sven; Hecimovic, Ante

    2014-03-15

    Krypton is sometimes used in physical vapor deposition processes due to its greater atomic mass and size compared to argon, which leads to a lower gas incorporation and may have beneficial effects on kinetics of the coating growth. In this paper, the authors investigate the plasma composition and properties of deposited high power pulse magnetron sputtering Cr-N coatings for discharges with various Ar/Kr ratios and for various pulse lengths of 40 μs, 80 μs, and 200 μs, keeping the average discharge power constant. The results show that an addition of Kr influences the discharge process by altering the ignition and peak values of the discharge current. This influences the metal ion generation and growth conditions on the substrate by reducing the nucleation site densities, leading to a predominantly columnar grow. However, the deposition rate is highest for an Ar/Kr ratio of 120/80. The integral of the metal ion and atom emission exhibits the same trend, having a maximum for Ar/Kr ratio of 120/80. By decreasing the pulse length, the deposition rate of coatings decreases, while the hardness increases.

  9. Method and apparatus for improved high power impulse magnetron sputtering

    DOEpatents

    Anders, Andre

    2013-11-05

    A high power impulse magnetron sputtering apparatus and method using a vacuum chamber with a magnetron target and a substrate positioned in the vacuum chamber. A field coil being positioned between the magnetron target and substrate, and a pulsed power supply and/or a coil bias power supply connected to the field coil. The pulsed power supply connected to the field coil, and the pulsed power supply outputting power pulse widths of greater that 100 .mu.s.

  10. Discharge Physics of High Power Impulse Magnetron Sputtering

    SciTech Connect

    Anders, Andre

    2010-10-13

    High power impulse magnetron sputtering (HIPIMS) is pulsed sputtering where the peak power exceeds the time-averaged power by typically two orders of magnitude. The peak power density, averaged over the target area, can reach or exceed 107 W/m2, leading to plasma conditions that make ionization of the sputtered atoms very likely. A brief review of HIPIMS operation is given in a tutorial manner, illustrated by some original data related to the self-sputtering of niobium in argon and krypton. Emphasis is put on the current-voltage-time relationships near the threshold of self-sputtering runaway. The great variety of current pulse shapes delivers clues on the very strong gas rarefaction, self-sputtering runaway conditions, and the stopping of runaway due to the evolution of atom ionization and ion return probabilities as the gas plasma is replaced by metal plasma. The discussions are completed by considering instabilities and the special case of ?gasless? self-sputtering.

  11. Microstructure and surface properties of chromium-doped diamond-like carbon thin films fabricated by high power pulsed magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Wu, Zhongzhen; Tian, Xiubo; Gui, Gang; Gong, Chunzhi; Yang, Shiqin; Chu, Paul K.

    2013-07-01

    High power pulsed magnetron sputtering (HPPMS) has attracted much interest due to the large plasma density and high ionization rate of sputtered materials. It is expected to produce a highly ionized C flux from a graphite target but unfortunately, the ionization rate of carbon is still very small and the discharge on a solid carbon target is unstable as well. In this work, a stable discharged chromium target is used in the preparation of chromium-doped diamond-like carbon (Cr-DLC) films in HPPMS in reactive C2H2 gas, but the unstable graphite. The chromium concentration in the Cr-DLC films is limited by surface poisoning due to reactive gas. Less than 2% of Cr is incorporated into the DLC films at C2H2 flow rate of 5 sccm or higher. However, as a result of the high ionization rate of the reactive gas in HPPMS, intense ion bombardment of the substrate is realized. The films show a smooth surface and a dense structure with a large sp3 concentration. As the C2H2 flow increase, the sp3 fraction increase and the sp3 to sp2 ratio increase to 0.75 at a C2H2 flow rate of 10 sccm. Compared to the substrate, the Cr-DLC films have lower friction and exhibit excellent corrosion resistance.

  12. Mixed-mode high-power impulse magnetron sputter deposition of tetrahedral amorphous carbon with pulse-length control of ionization

    NASA Astrophysics Data System (ADS)

    Tucker, M. D.; Ganesan, R.; McCulloch, D. G.; Partridge, J. G.; Stueber, M.; Ulrich, S.; Bilek, M. M. M.; McKenzie, D. R.; Marks, N. A.

    2016-04-01

    High-power impulse magnetron sputtering (HiPIMS) is used to deposit amorphous carbon thin films with sp3 fractions of 13% to 82%. Increasing the pulse length results in a transition from conventional HiPIMS deposition to a "mixed-mode" in which an arc triggers on the target surface, resulting in a large flux of carbon ions. The films are characterized using X-ray photoelectron spectroscopy, Raman spectroscopy, ellipsometry, nanoindentation, elastic recoil detection analysis, and measurements of stress and contact angle. All properties vary in a consistent manner, showing a high tetrahedral character only for long pulses, demonstrating that mixed-mode deposition is the source of the high carbon ion flux. Varying the substrate bias reveals an "energy window" effect, where the sp3 fraction of the films is greatest for a substrate bias around -100 V and decreases for higher or lower bias values. In the absence of bias, the films' properties show little dependence on the pulse length, showing that energetic ions are the origin of the highly tetrahedral character.

  13. Very low pressure high power impulse triggered magnetron sputtering

    DOEpatents

    Anders, Andre; Andersson, Joakim

    2013-10-29

    A method and apparatus are described for very low pressure high powered magnetron sputtering of a coating onto a substrate. By the method of this invention, both substrate and coating target material are placed into an evacuable chamber, and the chamber pumped to vacuum. Thereafter a series of high impulse voltage pulses are applied to the target. Nearly simultaneously with each pulse, in one embodiment, a small cathodic arc source of the same material as the target is pulsed, triggering a plasma plume proximate to the surface of the target to thereby initiate the magnetron sputtering process. In another embodiment the plasma plume is generated using a pulsed laser aimed to strike an ablation target material positioned near the magnetron target surface.

  14. Effect of oxygen incorporation on the structure and elasticity of Ti-Al-O-N coatings synthesized by cathodic arc and high power pulsed magnetron sputtering

    SciTech Connect

    Hans, M. Baben, M. to; Music, D.; Ebenhöch, J.; Schneider, J. M.; Primetzhofer, D.; Kurapov, D.; Arndt, M.; Rudigier, H.

    2014-09-07

    Ti-Al-O-N coatings were synthesized by cathodic arc and high power pulsed magnetron sputtering. The chemical composition of the coatings was determined by means of elastic recoil detection analysis and energy dispersive X-ray spectroscopy. The effect of oxygen incorporation on the stress-free lattice parameters and Young's moduli of Ti-Al-O-N coatings was investigated by X-ray diffraction and nanoindentation, respectively. As nitrogen is substituted by oxygen, implications for the charge balance may be expected. A reduction in equilibrium volume with increasing O concentration is identified by X-ray diffraction and density functional theory calculations of Ti-Al-O-N supercells reveal the concomitant formation of metal vacancies. Hence, the oxygen incorporation-induced formation of metal vacancies enables charge balancing. Furthermore, nanoindentation experiments reveal a decrease in elastic modulus with increasing O concentration. Based on ab initio data, two causes can be identified for this: First, the metal vacancy-induced reduction in elasticity; and second, the formation of, compared to the corresponding metal nitride bonds, relatively weak Ti-O and Al-O bonds.

  15. Reactive high power impulse magnetron sputtering: combining simulation and experiment

    NASA Astrophysics Data System (ADS)

    Kozak, Tomas; Vlcek, Jaroslav

    2016-09-01

    Reactive high-power impulse magnetron sputtering (HiPIMS) has recently been used for preparation of various oxide films with high application potential, such as TiO2, ZrO2, Ta2O5, HfO2, VO2. Using our patented method of pulsed reactive gas flow control with an optimized reactive gas inlet, we achieved significantly higher deposition rates compared to typical continuous dc magnetron depositions. We have developed a time-dependent model of the reactive HiPIMS. The model includes a depth-resolved description of the sputtered target (featuring sputtering, implantation and knock-on implantation processes) and a parametric description of the discharge plasma (dissociation of reactive gas, ionization and return of sputtered atoms and gas rarefaction). The model uses a combination of experimental and simulation data as input. We have calculated the composition of the target and substrate for several deposition conditions. The simulations predict a reduced compound coverage of the target in HiPIMS compared to the continuous dc sputtering regime which explains the increased deposition rate. The simulations show that an increased dissociation of oxygen in a HiPIMS discharge is beneficial to achieve stoichiometric films on the substrate at high deposition rates.

  16. High-power pulsed lasers

    SciTech Connect

    Holzrichter, J.F.

    1980-04-02

    The ideas that led to the successful construction and operation of large multibeam fusion lasers at the Lawrence Livermore Laboratory are reviewed. These lasers are based on the use of Nd:glass laser materials. However, most of the concepts are applicable to any laser being designed for fusion experimentation. This report is a summary of lectures given by the author at the 20th Scottish University Summer School in Physics, on Laser Plasma Interaction. This report includes basic concepts of the laser plasma system, a discussion of lasers that are useful for short-pulse, high-power operation, laser design constraints, optical diagnostics, and system organization.

  17. On the electron energy in the high power impulse magnetron sputtering discharge

    SciTech Connect

    Gudmundsson, J. T.; Sigurjonsson, P.; Larsson, P.; Lundin, D.; Helmersson, U.

    2009-06-15

    The temporal variation of the electron energy distribution function (EEDF) was measured with a Langmuir probe in a high power impulse magnetron sputtering (HiPIMS) discharge at 3 and 20 mTorr pressures. In the HiPIMS discharge a high power pulse is applied to a planar magnetron giving a high electron density and highly ionized sputtered vapor. The measured EEDF is Maxwellian-like during the pulse; it is broader for lower discharge pressure and it becomes narrower as the pulse progresses. This indicates that the plasma cools as the pulse progresses, probably due to high metal content of the discharge.

  18. Characterization of high power impulse magnetron sputtering discharges

    NASA Astrophysics Data System (ADS)

    Hala, Matej

    Paper I: In the first paper, we present a new approach in the characterization of the high power pulsed magnetron sputtering (HiPIMS) discharge evolution—time- and species-resolved plasma imaging—employing a set of band-pass optical interference filters suitable for the isolation of the emission originating from different species populating the plasma. We demonstrate that the introduction of such filters can be used to distinguish different phases of the discharge, and to visualize numerous plasma effects including background gas excitations during the discharge ignition, gas shock waves, and expansion of metal-rich plasmas. In particular, the application of this technique is shown on the diagnostics of the 200 µs long non-reactive HiPIMS discharges using a Cr target. Paper II: In order to gain further information about the dynamics of reactive HiPIMS discharges, both fast plasma imaging and time- and space-resolved optical emission spectroscopy (OES) are used for a systematic investigation of the 200 µs long HiPIMS pulses operated in Ar, N2 and N 2/Ar mixtures and at various pressures. It is observed that the dense metal plasma created next to the target propagates in the reactor at a speed ranging from 0.7 to 3.5 km s-1, depending on the working gas composition and the pressure. In fact, it increases with higher N 2 concentration and with lower pressure. The visible form of the propagating plasma wave changes from a hemispherical shape in Ar to a drop-like shape extending far from the target with increasing N2 concentration, owing to the significant emission from molecular N2. Interestingly, the evidence of the target self-sputtering is found for all investigated conditions, including pure N2 atmosphere. Paper III: Here, we report on the time- and species-resolved plasma imaging analysis of the dynamics of the 200 µs long HiPIMS discharges above a Cr target ignited in pure O2. It is shown that the discharge emission is dominated solely by neutral and

  19. Plasma potential mapping of high power impulse magnetron sputtering discharges

    SciTech Connect

    Rauch, Albert; Mendelsberg, Rueben J.; Sanders, Jason M.; Anders, Andre

    2011-12-20

    Pulsed emissive probe techniques have been used to determine the plasma potential distribution of high power impulse magnetron sputtering (HiPIMS) discharges. An unbalanced magnetron with a niobium target in argon was investigated for pulse length of 100 μs at a pulse repetition rate of 100 Hz, giving a peak current of 170 A. The probe data were taken with a time resolution of 20 ns and a spatial resolution of 1 mm. It is shown that the local plasma potential varies greatly in space and time. The lowest potential was found over the target’s racetrack, gradually reaching anode potential (ground) several centimeters away from the target. The magnetic pre-sheath exhibits a funnel-shaped plasma potential resulting in an electric field which accelerates ions toward the racetrack. In certain regions and times, the potential exhibits weak local maxima which allow for ion acceleration to the substrate. Knowledge of the local E and static B fields lets us derive the electrons’ E×B drift velocity, which is about 105 m/s and shows structures in space and time.

  20. Modeling of the Reactive High Power Impulse Magnetron Sputtering (HiPIMS) process

    NASA Astrophysics Data System (ADS)

    Gudmundsson, Jon Tomas; Lundin, Daniel; Raadu, Michael; Brenning, Nils; Minea, Tiberiu

    2015-09-01

    Reactive high power impulse magnetron sputtering (HiPIMS) provides both a high ionization fraction of the sputtered material and a high dissociation fraction of the molecular gas. We demonstrate this through an ionization region model (IRM) of the reactive Ar/O2 HiPIMS discharge with a titanium target. We explore the influence of oxygen dilution on the discharge properties such as electron density, the ionization fraction of the sputtered vapor and the oxygen dissociation fraction. We discuss the important processes and challenges for more detailed modeling of the reactive HiPIMS discharge. Furthermore, we discuss experimental observations during reactive high power impulse magnetron sputtering sputtering (HiPIMS) of Ti target in Ar/N2 and Ar/O2 atmosphere. The discharge current waveform is highly dependent on the reactive gas flow rate, pulse repetition frequency and discharge voltage. The discharge current increases with decreasing repetition frequency and increasing flowrate of the reactive gas.

  1. Pulsed high-power beams

    SciTech Connect

    Reginato, L.L.; Birx, D.L.

    1988-06-01

    The marriage of induction linac technology with nonlinear magnetic modulators has produced some unique capabilities. It is now possible to produce short-pulse electron beams with average currents measured in amperes, at gradients approaching 1-MeV/m, and with power efficiencies exceeding 50%. A 70-Mev, 3-kA induction accelerator (ETA II) constructed at the Lawrence Livermore National Laboratory incorporates the pulse technology concepts that have evolved over the past several years. The ETA II is a linear induction accelerator and provides a test facility for demonstration of the high-average-power components and high-brightness sources used in such accelerators. The pulse drive for the accelerator is based on state-of-the-art magnetic pulse compressors with very high peak-power capability, repetition rates exceeding 1 kHz, and excellent reliability. 6 figs.

  2. High power ultrashort pulse lasers

    SciTech Connect

    Perry, M.D.

    1994-10-07

    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.

  3. High-power picosecond laser pulse recirculation.

    PubMed

    Shverdin, M Y; Jovanovic, I; Semenov, V A; Betts, S M; Brown, C; Gibson, D J; Shuttlesworth, R M; Hartemann, F V; Siders, C W; Barty, C P J

    2010-07-01

    We demonstrate a nonlinear crystal-based short pulse recirculation cavity for trapping the second harmonic of an incident high-power laser pulse. This scheme aims to increase the efficiency and flux of Compton-scattering-based light sources. We demonstrate up to 40x average power enhancement of frequency-doubled submillijoule picosecond pulses, and 17x average power enhancement of 177 mJ, 10 ps, 10 Hz pulses.

  4. High Power Picosecond Laser Pulse Recirculation

    SciTech Connect

    Shverdin, M Y; Jovanovic, I; Semenov, V A; Betts, S M; Brown, C; Gibson, D J; Shuttlesworth, R M; Hartemann, F V; Siders, C W; Barty, C P

    2010-04-12

    We demonstrate a nonlinear crystal-based short pulse recirculation cavity for trapping the second harmonic of an incident high power laser pulse. This scheme aims to increase the efficiency and flux of Compton-scattering based light sources. We demonstrate up to 36x average power enhancement of frequency doubled sub-millijoule picosecond pulses, and 17x average power enhancement of 177 mJ, 10 ps, 10 Hz pulses.

  5. Discharge current modes of high power impulse magnetron sputtering

    SciTech Connect

    Wu, Zhongzhen Xiao, Shu; Ma, Zhengyong; Cui, Suihan; Ji, Shunping; Pan, Feng; Tian, Xiubo; Fu, Ricky K. Y.; Chu, Paul K.

    2015-09-15

    Based on the production and disappearance of ions and electrons in the high power impulse magnetron sputtering plasma near the target, the expression of the discharge current is derived. Depending on the slope, six possible modes are deduced for the discharge current and the feasibility of each mode is discussed. The discharge parameters and target properties are simplified into the discharge voltage, sputtering yield, and ionization energy which mainly affect the discharge plasma. The relationship between these factors and the discharge current modes is also investigated.

  6. Are the argon metastables important in high power impulse magnetron sputtering discharges?

    SciTech Connect

    Gudmundsson, J. T.; Lundin, D.; Minea, T. M.; Stancu, G. D.; Brenning, N.

    2015-11-15

    We use an ionization region model to explore the ionization processes in the high power impulse magnetron sputtering (HiPIMS) discharge in argon with a titanium target. In conventional dc magnetron sputtering (dcMS), stepwise ionization can be an important route for ionization of the argon gas. However, in the HiPIMS discharge stepwise ionization is found to be negligible during the breakdown phase of the HiPIMS pulse and becomes significant (but never dominating) only later in the pulse. For the sputtered species, Penning ionization can be a significant ionization mechanism in the dcMS discharges, while in the HiPIMS discharge Penning ionization is always negligible as compared to electron impact ionization. The main reasons for these differences are a higher plasma density in the HiPIMS discharge, and a higher electron temperature. Furthermore, we explore the ionization fraction and the ionized flux fraction of the sputtered vapor and compare with recent experimental work.

  7. High power impulse magnetron sputtering: Current-voltage-timecharacteristics indicate the onset of sustained self-sputtering

    SciTech Connect

    Anders, Andre; Andersson, Joakim; Ehiasarian, Arutiun

    2007-08-03

    The commonly used current-voltage characteristics are foundinadequate for describing the pulsed nature of the high power impulsemagnetron sputtering (HIPIMS) discharge, rather, the description needs tobe expanded to current-voltage-time characteristics for each initial gaspressure. Using different target materials (Cu, Ti, Nb, C, W, Al, Cr) anda pulsed constant-voltage supply it is shown that the HIPIMS dischargestypically exhibit an initial pressure dependent current peak followed bya second phase that is power and material dependent. This suggests thatthe initial phase of a HIPIMS discharge pulse is dominated by gas ionswhereas the later phase has a strong contribution from self-sputtering.For some materials the discharge switches into a mode of sustainedself-sputtering. The very large differences between materials cannot beascribed to the different sputter yields but they indicate thatgeneration and trapping ofsecondary electrons plays a major role forcurrent-voltage-time characteristics. In particular, it is argued thatthe sustained self-sputtering phase is associated with thegeneration ofmultiply charged ions because only they can cause potential emission ofsecondary electrons whereas the yield caused by singly charged metal ionsis negligibly small.

  8. Influence of pulse duration on the plasma characteristics in high-power pulsed magnetron discharges

    SciTech Connect

    Konstantinidis, S.; Dauchot, J.P.; Ganciu, M.; Ricard, A.; Hecq, M.

    2006-01-01

    High-power pulsed magnetron discharges have drawn an increasing interest as an approach to produce highly ionized metallic vapor. In this paper we propose to study how the plasma composition and the deposition rate are influenced by the pulse duration. The plasma is studied by time-resolved optical emission and absorption spectroscopies and the deposition rate is controlled thanks to a quartz microbalance. The pulse length is varied between 2.5 and 20 {mu}s at 2 and 10 mTorr in pure argon. The sputtered material is titanium. For a constant discharge power, the deposition rate increases as the pulse length decreases. With 5 {mu}s pulse, for an average power of 300 W, the deposition rate is {approx}70% of the deposition rate obtained in direct current magnetron sputtering at the same power. The increase of deposition rate can be related to the sputtering regime. For long pulses, self-sputtering seems to occur as demonstrated by time-resolved optical emission diagnostic of the discharge. In contrary, the metallic vapor ionization rate, as determined by absorption measurements, diminishes as the pulses are shortened. Nevertheless, the ionization rate is in the range of 50% for 5 {mu}s pulses while it lies below 10% in the case of a classical continuous magnetron discharge.

  9. Plasma"anti-assistance" and"self-assistance" to high power impulse magnetron sputtering

    SciTech Connect

    Anders, Andre; Yushkov, Georgy Yu.

    2009-01-30

    A plasma assistance system was investigated with the goal to operate high power impulse magnetron sputtering (HiPIMS) at lower pressure than usual, thereby to enhance the utilization of the ballistic atoms and ions with high kinetic energy in the film growth process. Gas plasma flow from a constricted plasma source was aimed at the magnetron target. Contrary to initial expectations, such plasma assistance turned out to be contra-productive because it led to the extinction of the magnetron discharge. The effect can be explained by gas rarefaction. A better method of reducing the necessary gas pressure is operation at relatively high pulse repetition rates where the afterglow plasma of one pulse assists in the development of the next pulse. Here we show that this method, known from medium-frequency (MF) pulsed sputtering, is also very important at the much lower pulse repetition rates of HiPIMS. A minimum in the possible operational pressure is found in the frequency region between HiPIMS and MF pulsed sputtering.

  10. High power impulse magnetron sputtering and related discharges: scalable plasma sources for plasma-based ion implantation and deposition

    SciTech Connect

    Anders, Andre

    2009-09-01

    High power impulse magnetron sputtering (HIPIMS) and related self-sputtering techniques are reviewed from a viewpoint of plasma-based ion implantation and deposition (PBII&D). HIPIMS combines the classical, scalable sputtering technology with pulsed power, which is an elegant way of ionizing the sputtered atoms. Related approaches, such as sustained self-sputtering, are also considered. The resulting intense flux of ions to the substrate consists of a mixture of metal and gas ions when using a process gas, or of metal ions only when using `gasless? or pure self-sputtering. In many respects, processing with HIPIMS plasmas is similar to processing with filtered cathodic arc plasmas, though the former is easier to scale to large areas. Both ion implantation and etching (high bias voltage, without deposition) and thin film deposition (low bias, or bias of low duty cycle) have been demonstrated.

  11. Rarefaction windows in a high-power impulse magnetron sputtering plasma

    SciTech Connect

    Palmucci, Maria; Britun, Nikolay; Konstantinidis, Stephanos; Snyders, Rony

    2013-09-21

    The velocity distribution function of the sputtered particles in the direction parallel to the planar magnetron cathode is studied by spatially- and time-resolved laser-induced fluorescence spectroscopy in a short-duration (20 μs) high-power impulse magnetron sputtering discharge. The experimental evidence for the neutral and ionized sputtered particles to have a constant (saturated) velocity at the end of the plasma on-time is demonstrated. The velocity component parallel to the target surface reaches the values of about 5 km/s for Ti atoms and ions, which is higher that the values typically measured in the direct current sputtering discharges before. The results point out on the presence of a strong gas rarefaction significantly reducing the sputtered particles energy dissipation during a certain time interval at the end of the plasma pulse, referred to as “rarefaction window” in this work. The obtained results agree with and essentially clarify the dynamics of HiPIMS discharge studied during the plasma off-time previously in the work: N. Britun, Appl. Phys. Lett. 99, 131504 (2011)

  12. Plasma reactivity in high-power impulse magnetron sputtering through oxygen kinetics

    SciTech Connect

    Vitelaru, Catalin; Lundin, Daniel; Brenning, Nils; Minea, Tiberiu

    2013-09-02

    The atomic oxygen metastable dynamics in a Reactive High-Power Impulse Magnetron Sputtering (R-HiPIMS) discharge has been characterized using time-resolved diode laser absorption in an Ar/O{sub 2} gas mixture with a Ti target. Two plasma regions are identified: the ionization region (IR) close to the target and further out the diffusion region (DR), separated by a transition region. The μs temporal resolution allows identifying the main atomic oxygen production and destruction routes, which are found to be very different during the pulse as compared to the afterglow as deduced from their evolution in space and time.

  13. Ground state atomic oxygen in high-power impulse magnetron sputtering: a quantitative study

    NASA Astrophysics Data System (ADS)

    Britun, Nikolay; Belosludtsev, Alexandr; Silva, Tiago; Snyders, Rony

    2017-02-01

    The ground state density of oxygen atoms in reactive high-power impulse magnetron sputtering discharges has been studied quantitatively. Both time-resolved and space-resolved measurements were conducted. The measurements were performed using two-photon absorption laser-induced fluorescence (TALIF), and calibrated by optical emission actinometry with multiple Ar emission lines. The results clarify the dynamics of the O ground state atoms in the discharge afterglow significantly, including their propagation and fast decay after the plasma pulse, as well as the influence of gas pressure, O2 admixture, etc.

  14. Earthquake Triggering by High Power Electric Pulses

    NASA Astrophysics Data System (ADS)

    Novikov, Victor; Konev, Yuri; Zeigarnik, Vladimir

    2010-05-01

    The study carried out by the Joint Institute for High Temperatures in cooperation with the Institute of Physics of the Earth and the Research Station in Bishkek of Russian Academy of Sciences in 1999-2008 showed a response of weak seismicity at field experiments with electric pulsed power systems, as well as acoustic emission of rock specimens under laboratory conditions on high-power electric current pulses applied to the rocks. It was suggested that the phenomenon discovered may be used in practice for partial release of tectonic stresses in the Earth crust for earthquake hazard mitigation. Nevertheless, the mechanism of the influence of man-made electromagnetic field on the regional seismicity is not clear yet. One of possible cause of the phenomenon may be pore fluid pressure increase in the rocks under stressed conditions due to Joule heat generation by electric current injected into the Earth crust. It is known that increase of pore fluid pressure in the fault zone over a critical pressure of about 0.05 MPa is sufficient to trigger an earthquake if the fault is near the critical state due to accumulated tectonic deformations. Detailed 3D-calculaton of electric current density in the Earth crust of the Northern Tien Shan provided by pulsed electric high-power system connected to grounded electric dipole showed that at the depth of earthquake epicenters (over 5 km) the electric current density is lower than 10-7 A/m2 that is not sufficient for increase of pressure in the fluid-saturated porous geological medium due to Joule heat generation, which may provide formation of cracks resulting in the fault propagation and release of tectonic stresses in the Earth crust. Nevertheless, under certain conditions, when electric current will be injected into the fault through the casing pipes of two deep wells with preliminary injection of conductive fluid into the fault, the current density may be high enough for significant increase of mechanic pressure in the porous two

  15. Duty cycle control in reactive high-power impulse magnetron sputtering of hafnium and niobium

    NASA Astrophysics Data System (ADS)

    Ganesan, R.; Treverrow, B.; Murdoch, B.; Xie, D.; Ross, A. E.; Partridge, J. G.; Falconer, I. S.; McCulloch, D. G.; McKenzie, D. R.; Bilek, M. M. M.

    2016-06-01

    Instabilities in reactive sputtering have technological consequences and have been attributed to the formation of a compound layer on the target surface (‘poisoning’). Here we demonstrate how the duty cycle of high power impulse magnetron sputtering (HiPIMS) can be used to control the surface conditions of Hf and Nb targets. Variations in the time resolved target current characteristics as a function of duty cycle were attributed to gas rarefaction and to the degree of poisoning of the target surface. As the operation transitions from Ar driven sputtering to metal driven sputtering, the secondary electron emission changes and reduces the target current. The target surface transitions smoothly from a poisoned state at low duty cycles to a quasi-metallic state at high duty cycles. Appropriate selection of duty cycle increases the deposition rate, eliminates the need for active regulation of oxygen flow and enables stable reactive deposition of stoichiometric metal oxide films. A model is presented for the reactive HIPIMS process in which the target operates in a partially poisoned mode with different degrees of oxide layer distribution on its surface that depends on the duty cycle. Finally, we show that by tuning the pulse characteristics, the refractive indices of the metal oxides can be controlled without increasing the absorption coefficients, a result important for the fabrication of optical multilayer stacks.

  16. Current-voltage-time characteristics of the reactive Ar/N{sub 2} high power impulse magnetron sputtering discharge

    SciTech Connect

    Magnus, F.; Sveinsson, O. B.; Olafsson, S.; Gudmundsson, J. T.

    2011-10-15

    The discharge current and voltage waveforms have been measured in a reactive high power impulse magnetron sputtering (HiPIMS) Ar/N{sub 2} discharge with a Ti target for 400 {mu}s long pulses. We observe that the current waveform in the reactive Ar/N{sub 2} HiPIMS discharge is highly dependent on the pulse repetition frequency, unlike the non-reactive Ar discharge. The current is found to increase significantly as the frequency is lowered. This is attributed to an increase in the secondary electron emission yield during the self-sputtering phase, when the nitride forms on the target at low frequencies. In addition, self-sputtering runaway occurs at lower discharge voltages when nitrogen is added to the discharge. This illustrates the crucial role of self-sputtering in the behavior of the reactive HiPIMS discharge.

  17. High power linear pulsed beam annealer

    DOEpatents

    Strathman, Michael D.; Sadana, Devendra K.; True, Richard B.

    1983-01-01

    A high power pulsed electron beam is produced in a system comprised of an electron gun having a heated cathode, control grid, focus ring, and a curved drift tube. The drift tube is maintained at a high positive voltage with respect to the cathode to accelerate electrons passing through the focus ring and to thereby eliminate space charge. A coil surrounding the curved drift tube provides a magnetic field which maintains the electron beam focused about the axis of the tube and imparts motion on electrons in a spiral path for shallow penetration of the electrons into a target. The curvature of the tube is selected so there is no line of sight between the cathode and a target holder positioned within a second drift tube spaced coaxially from the curved tube. The second tube and the target holder are maintained at a reference voltage that decelerates the electrons. A second coil surrounding the second drift tube maintains the electron beam focused about the axis of the second drift tube and compresses the electron beam to the area of the target. The target holder can be adjusted to position the target where the cross section of the beam matches the area of the target.

  18. Plasma diagnostics of low pressure high power impulse magnetron sputtering assisted by electron cyclotron wave resonance plasma

    SciTech Connect

    Stranak, Vitezslav; Herrendorf, Ann-Pierra; Drache, Steffen; Bogdanowicz, Robert; Hippler, Rainer; Cada, Martin; Hubicka, Zdenek; Tichy, Milan

    2012-11-01

    This paper reports on an investigation of the hybrid pulsed sputtering source based on the combination of electron cyclotron wave resonance (ECWR) inductively coupled plasma and high power impulse magnetron sputtering (HiPIMS) of a Ti target. The plasma source, operated in an Ar atmosphere at a very low pressure of 0.03 Pa, provides plasma where the major fraction of sputtered particles is ionized. It was found that ECWR assistance increases the electron temperature during the HiPIMS pulse. The discharge current and electron density can achieve their stable maximum 10 {mu}s after the onset of the HiPIMS pulse. Further, a high concentration of double charged Ti{sup ++} with energies of up to 160 eV was detected. All of these facts were verified experimentally by time-resolved emission spectroscopy, retarding field analyzer measurement, Langmuir probe, and energy-resolved mass spectrometry.

  19. Spatial and temporal evolution of ion energies in high power impulse magnetron sputtering plasma discharge

    NASA Astrophysics Data System (ADS)

    Hecimovic, A.; Ehiasarian, A. P.

    2010-09-01

    High power impulse magnetron sputtering (HIPIMS) is a novel deposition technology successfully implemented on full scale industrial machines. HIPIMS utilizes short pulses of high power delivered to the target in order to generate high amount of metal ions. The life-span of ions between the pulses and their energy distribution could strongly influence the properties and characteristics of the deposited coating. In modern industrial coating machines the sample rotates on a substrate holder and changes its position and distance with regard to the magnetron. Time resolved measurements of the ion energy distribution function (IEDF) at different distances from the magnetron have been performed to investigate the temporal evolution of ions at various distances from target. The measurements were performed using two pressures, 1 and 3 Pa to investigate the influence of working gas pressure on IEDF. Plasma sampling energy-resolved mass spectroscopy was used to measure the IEDF of Ti1+, Ti2+, Ar1+, and Ar2+ ions in HIPIMS plasma discharge with titanium (Ti) target in Ar atmosphere. The measurements were done over a full pulse period and the distance between the magnetron and the orifice of the mass spectrometer was changed from 25 to 215 mm.

  20. Silicon oxynitride films deposited by reactive high power impulse magnetron sputtering using nitrous oxide as a single-source precursor

    SciTech Connect

    Hänninen, Tuomas Schmidt, Susann; Jensen, Jens; Hultman, Lars; Högberg, Hans

    2015-09-15

    Silicon oxynitride thin films were synthesized by reactive high power impulse magnetron sputtering of silicon in argon/nitrous oxide plasmas. Nitrous oxide was employed as a single-source precursor supplying oxygen and nitrogen for the film growth. The films were characterized by elastic recoil detection analysis, x-ray photoelectron spectroscopy, x-ray diffraction, x-ray reflectivity, scanning electron microscopy, and spectroscopic ellipsometry. Results show that the films are silicon rich, amorphous, and exhibit a random chemical bonding structure. The optical properties with the refractive index and the extinction coefficient correlate with the film elemental composition, showing decreasing values with increasing film oxygen and nitrogen content. The total percentage of oxygen and nitrogen in the films is controlled by adjusting the gas flow ratio in the deposition processes. Furthermore, it is shown that the film oxygen-to-nitrogen ratio can be tailored by the high power impulse magnetron sputtering-specific parameters pulse frequency and energy per pulse.

  1. Origin of the Delayed Current Onset in High Power Impulse Magnetron Sputtering

    SciTech Connect

    Yushkov, Georgy Yu.; Anders, Andre

    2010-07-19

    Repetitive pulses of voltage and current are applied in high power impulse magnetron sputtering. The current pulse usually lags the applied voltage by a significant time, which in some cases can reach many 10s of microseconds. The current time lag is generally highly reproducible and jitters less than 1percent of the delay time. This work investigates the time lag experimentally and theoretically. The experiments include several different target and gas combinations, voltage and current amplitudes, gas pressures, pulse repetition rates, and pulse durations. It is shown that in all cases the inverse delay is approximately proportional to the applied voltage, where the proportionality factor depends on the combination of materials and the conditions selected. The proportionality factor contains the parameters of ionization and secondary electron emission. The statistical time lag is negligible while the formative time lag is large and usually dominated by the ion motion (inertia), although, at low pressure, the long free path of magnetized electrons causing ionization contributes to the delay.

  2. Self-sputtering runaway in high power impulse magnetron sputtering: The role of secondary electrons and multiply charged metal ions

    SciTech Connect

    Anders, Andre

    2008-05-19

    Self-sputtering runaway in high power impulse magnetron sputtering is closely related to the appearance of multiply charged ions. This conclusion is based on the properties of potential emission of secondary electrons and energy balance considerations. The effect is especially strong for materials whose sputtering yield is marginally greater than unity. The absolute deposition rate increases {approx}Q{sup 1/2}, whereas the rate normalized to the average power decreases {approx}Q{sup -1/2}, with Q being the mean ion charge state number.

  3. DEPOSITION OF NIOBIUM AND OTHER SUPERCONDUCTING MATERIALS WITH HIGH POWER IMPULSE MAGNETRON SPUTTERING: CONCEPT AND FIRST RESULTS

    SciTech Connect

    High Current Electronics Institute, Tomsk, Russia; Anders, Andre; Mendelsberg, Rueben J.; Lim, Sunnie; Mentink, Matthijs; Slack, Jonathan L.; Wallig, Joseph G.; Nollau, Alexander V.; Yushkov, Georgy Yu.

    2011-07-24

    Niobium coatings on copper cavities have been considered as a cost-efficient replacement of bulk niobium RF cavities, however, coatings made by magnetron sputtering have not quite lived up to high expectations due to Q-slope and other issues. High power impulse magnetron sputtering (HIPIMS) is a promising emerging coatings technology which combines magnetron sputtering with a pulsed power approach. The magnetron is turned into a metal plasma source by using very high peak power density of ~ 1 kW/cm{sup 2}. In this contribution, the cavity coatings concept with HIPIMS is explained. A system with two cylindrical, movable magnetrons was set up with custom magnetrons small enough to be inserted into 1.3 GHz cavities. Preliminary data on niobium HIPIMS plasma and the resulting coatings are presented. The HIPIMS approach has the potential to be extended to film systems beyond niobium, including other superconducting materials and/or multilayer systems.

  4. High power UV and VUV pulsed excilamps

    NASA Astrophysics Data System (ADS)

    Tarasenko, V.; Erofeev, M.; Lomaev, M.; Rybka, D.

    2008-07-01

    Emission characteristics of a nanosecond discharge in inert gases and its halogenides without preionization of the gap from an auxiliary source have been investigated. A volume discharge, initiated by an avalanche electron beam (VDIAEB) was realized at pressures up to 12 atm. In xenon at pressure of 1.2 atm, the energy of spontaneous radiation in the full solid angle was sim 45 mJ/cm^3, and the FWHM of a radiation pulse was sim 110 ns. The spontaneous radiation power rise in xenon was observed at pressures up to 12 atm. Pulsed radiant exitance of inert gases halogenides excited by VDIAEB was sim 4.5 kW/cm^2 at efficiency up to 5.5 %.

  5. High power parallel ultrashort pulse laser processing

    NASA Astrophysics Data System (ADS)

    Gillner, Arnold; Gretzki, Patrick; Büsing, Lasse

    2016-03-01

    The class of ultra-short-pulse (USP) laser sources are used, whenever high precession and high quality material processing is demanded. These laser sources deliver pulse duration in the range of ps to fs and are characterized with high peak intensities leading to a direct vaporization of the material with a minimum thermal damage. With the availability of industrial laser source with an average power of up to 1000W, the main challenge consist of the effective energy distribution and disposition. Using lasers with high repetition rates in the MHz region can cause thermal issues like overheating, melt production and low ablation quality. In this paper, we will discuss different approaches for multibeam processing for utilization of high pulse energies. The combination of diffractive optics and conventional galvometer scanner can be used for high throughput laser ablation, but are limited in the optical qualities. We will show which applications can benefit from this hybrid optic and which improvements in productivity are expected. In addition, the optical limitations of the system will be compiled, in order to evaluate the suitability of this approach for any given application.

  6. Method to control deposition rate instabilities—High power impulse magnetron sputtering deposition of TiO{sub 2}

    SciTech Connect

    Kossoy, Anna E-mail: anna.kossoy@gmail.com; Magnusson, Rögnvaldur L.; Tryggvason, Tryggvi K.; Leosson, Kristjan; Olafsson, Sveinn

    2015-03-15

    The authors describe how changes in shutter state (open/closed) affect sputter plasma conditions and stability of the deposition rate of Ti and TiO{sub 2} films. The films were grown by high power impulse magnetron sputtering in pure Ar and in Ar/O{sub 2} mixture from a metallic Ti target. The shutter state was found to have an effect on the pulse waveform for both pure Ar and reactive sputtering of Ti also affecting stability of TiO{sub 2} deposition rate. When the shutter opened, the shape of pulse current changed from rectangular to peak-plateau and pulse energy decreased. The authors attribute it to the change in plasma impedance and gas rarefaction originating in geometry change in front of the magnetron. TiO{sub 2} deposition rate was initially found to be high, 1.45 Å/s, and then dropped by ∼40% during the first 5 min, while for Ti the change was less obvious. Instability of deposition rate poses significant challenge for growing multilayer heterostructures. In this work, the authors suggest a way to overcome this by monitoring the integrated average energy involved in the deposition process. It is possible to calibrate and control the film thickness by monitoring the integrated pulse energy and end growth when desired integrated pulse energy level has been reached.

  7. Time resolved ion energy distribution functions of non-reactive and reactive high power impulse magnetron sputtering of titanium

    NASA Astrophysics Data System (ADS)

    Grosse, Katharina; Breilmann, Wolfgang; Maszl, Christian; Benedikt, Jan; von Keudell, Achim

    2016-09-01

    High power impulse magnetron sputtering (HiPIMS) is a technique for thin film deposition and can be operated in reactive and non-reactive mode. The growth rate of HiPIMS in non-reactive mode reduces to 30% compared to direct current magnetron sputtering (dcMS) at same average power. However, the quality of the coatings produced with HiPIMS is excellent which makes these plasmas highly appealing. In reactive mode target poisoning is occurring which changes the plasma dynamics. An advantage of reactive HiPIMS is that it can be operated hysteresis-free which can result in a higher growth rate compared to dcMS. In this work thin films are deposited by a HiPIMS plasma which is generated by short pulses of 100 μs with high power densities in the range of 1 kW/cm2. Ar and Ar/N2 admixtures are used as a working gas to sputter a 2'' titanium target. The particle transport is analysed with time resolved ion energy distribution functions which are measured by a mass spectrometer with a temporal resolution of 2 μs. Phase resolved optical emission spectroscopy is executed to investigate the particle dynamics of different species. The time and energy resolved particle fluxes in non-reactive and reactive mode are compared and implications on the sputter process are discussed.

  8. Pulsed High Power Microwave (HPM) Oscillator with Phasing Capability

    DTIC Science & Technology

    2013-06-01

    REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Pulsed High Power Microwave (HPM) Oscillator with Phasing Capability 5a. CONTRACT...public release, distribution unlimited 13. SUPPLEMENTARY NOTES See also ADM002371. 2013 IEEE Pulsed Power Conference, Digest of Technical Papers 1976

  9. Deposition Rates of High Power Impulse Magnetron Sputtering: Physics and Economics

    SciTech Connect

    Anders, Andre

    2009-11-22

    Deposition by high power impulse magnetron sputtering (HIPIMS) is considered by some as the new paradigm of advanced sputtering technology, yet this is met with skepticism by others for the reported lower deposition rates, if compared to rates of more conventional sputtering of equal average power. In this contribution, the underlying physical reasons for the rate changes are discussed, including (i) ion return to the target and self-sputtering, (ii) the less-than-linear increase of the sputtering yield with increasing ion energy, (iii) yield changes due to the shift of species responsible for sputtering, (iv) changes to due to greater film density, limited sticking, and self-sputtering on the substrate, (v) noticeable power losses in the switch module, (vi) changes of the magnetic balance and particle confinement of the magnetron due to self-fields at high current, and (vii) superposition of sputtering and sublimation/evaporation for selected materials. The situation is even more complicated for reactive systems where the target surface chemistry is a function of the reactive gas partial pressure and discharge conditions. While most of these factors imply a reduction of the normalized deposition rate, increased rates have been reported for certain conditions using hot targets and less poisoned targets. Finally, some points of economics and HIPIMS benefits considered.

  10. Evaporation-assisted high-power impulse magnetron sputtering: The deposition of tungsten oxide as a case study

    SciTech Connect

    Hemberg, Axel; Dauchot, Jean-Pierre; Snyders, Rony; Konstantinidis, Stephanos

    2012-07-15

    The deposition rate during the synthesis of tungsten trioxide thin films by reactive high-power impulse magnetron sputtering (HiPIMS) of a tungsten target increases, above the dc threshold, as a result of the appropriate combination of the target voltage, the pulse duration, and the amount of oxygen in the reactive atmosphere. This behavior is likely to be caused by the evaporation of the low melting point tungsten trioxide layer covering the metallic target in such working conditions. The HiPIMS process is therefore assisted by thermal evaporation of the target material.

  11. Investigation of ionized metal flux in enhanced high power impulse magnetron sputtering discharges

    SciTech Connect

    Stranak, Vitezslav; Hubicka, Zdenek; Cada, Martin; Drache, Steffen; Hippler, Rainer; Tichy, Milan

    2014-04-21

    The metal ionized flux fraction and production of double charged metal ions Me{sup 2+} of different materials (Al, Cu, Fe, Ti) by High Power Impulse Magnetron Sputtering (HiPIMS) operated with and without a pre-ionization assistance is compared in the paper. The Electron Cyclotron Wave Resonance (ECWR) discharge was employed as the pre-ionization agent providing a seed of charge in the idle time of HiPIMS pulses. A modified grid-free biased quartz crystal microbalance was used to estimate the metal ionized flux fraction ξ. The energy-resolved mass spectrometry served as a complementary method to distinguish particular ion contributions to the total ionized flux onto the substrate. The ratio between densities of doubly Me{sup 2+} and singly Me{sup +} charged metal ions was determined. It is shown that ECWR assistance enhances Me{sup 2+} production with respect of absorbed rf-power. The ECWR discharge also increases the metal ionized flux fraction of about 30% especially in the region of lower pressures. Further, the suppression of the gas rarefaction effect due to enhanced secondary electron emission of Me{sup 2+} was observed.

  12. Pulsed Beamless High Power Microwave (HPM) Source with Integrated Antenna

    DTIC Science & Technology

    2013-06-01

    gral part of t utilized for source ope d. The peak asured to be 2 ns. SS HIGH IN kach Institu .Mironenk iv 04073, U SA; Ya. T 1 er Microwave W...Pulsed Beamless High Power Microwave (HPM) Source With Integrated Antenna 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6...NOTES See also ADM002371. 2013 IEEE Pulsed Power Conference, Digest of Technical Papers 1976-2013, and Abstracts of the 2013 IEEE International

  13. Review of Literature on High Power Microwave Pulse Biological Effects

    DTIC Science & Technology

    2009-08-01

    AFRL-RH-BR-TR-2009-0068 Review of Literature on High Power Microwave Pulse Biological Effects Ronald L. Seaman General...2009 Air Force Research Laboratory 711 Human Performance Wing Human Effectiveness Directorate Directed Energy Bioeffects...Performance Wing Human Effectiveness Directorate This report is published in the interest of scientific and technical information exchange

  14. Pulsed dc self-sustained magnetron sputtering

    SciTech Connect

    Wiatrowski, A.; Posadowski, W. M.; Radzimski, Z. J.

    2008-09-15

    The magnetron sputtering has become one of the commonly used techniques for industrial deposition of thin films and coatings due to its simplicity and reliability. At standard magnetron sputtering conditions (argon pressure of {approx}0.5 Pa) inert gas particles (necessary to sustain discharge) are often entrapped in the deposited films. Inert gas contamination can be eliminated during the self-sustained magnetron sputtering (SSS) process, where the presence of the inert gas is not a necessary requirement. Moreover the SSS process that is possible due to the high degree of ionization of the sputtered material also gives a unique condition during the transport of sputtered particles to the substrate. So far it has been shown that the self-sustained mode of magnetron operation can be obtained using dc powering (dc-SSS) only. The main disadvantage of the dc-SSS process is its instability related to random arc formation. In such case the discharge has to be temporarily extinguished to prevent damaging both the magnetron source and power supply. The authors postulate that pulsed powering could protect the SSS process against arcs, similarly to reactive pulsed magnetron deposition processes of insulating thin films. To put this concept into practice, (i) the high enough plasma density has to be achieved and (ii) the type of pulsed powering has to be chosen taking plasma dynamics into account. In this article results of pulsed dc self-sustained magnetron sputtering (pulsed dc-SSS) are presented. The planar magnetron equipped with a 50 mm diameter and 6 mm thick copper target was used during the experiments. The maximum target power was about 11 kW, which corresponded to the target power density of {approx}560 W/cm{sup 2}. The magnetron operation was investigated as a function of pulse frequency (20-100 kHz) and pulse duty factor (50%-90%). The discharge (argon) extinction pressure level was determined for these conditions. The plasma emission spectra (400-410 nm range

  15. High power repetitive TEA CO2 pulsed laser

    NASA Astrophysics Data System (ADS)

    Yang, Guilong; Li, Dianjun; Xie, Jijiang; Zhang, Laiming; Chen, Fei; Guo, Jin; Guo, Lihong

    2012-07-01

    A high power repetitive spark-pin UV-preionized TEA CO2 laser system is presented. The discharge for generating laser pulses is controlled by a rotary spark switch and a high voltage pulsed trigger. Uniform glow discharge between two symmetrical Chang-electrodes is realized by using an auto-inversion circuit. A couple of high power axial-flow fans with the maximum wind speed of 80 m/s are used for gas exchange between the electrodes. At a repetitive operation, the maximum average output laser power of 10.4 kW 10.6 μm laser is obtained at 300 Hz, with an electro-optical conversion efficiency of 15.6%. At single pulsed operation, more pumping energy and higher gases pressures can be injected, and the maximum output laser energy of 53 J is achieved.

  16. Process stabilization by peak current regulation in reactive high-power impulse magnetron sputtering of hafnium nitride

    NASA Astrophysics Data System (ADS)

    Shimizu, T.; Villamayor, M.; Lundin, D.; Helmersson, U.

    2016-02-01

    A simple and cost effective approach to stabilize the sputtering process in the transition zone during reactive high-power impulse magnetron sputtering (HiPIMS) is proposed. The method is based on real-time monitoring and control of the discharge current waveforms. To stabilize the process conditions at a given set point, a feedback control system was implemented that automatically regulates the pulse frequency, and thereby the average sputtering power, to maintain a constant maximum discharge current. In the present study, the variation of the pulse current waveforms over a wide range of reactive gas flows and pulse frequencies during a reactive HiPIMS process of Hf-N in an Ar-N2 atmosphere illustrates that the discharge current waveform is a an excellent indicator of the process conditions. Activating the reactive HiPIMS peak current regulation, stable process conditions were maintained when varying the N2 flow from 2.1 to 3.5 sccm by an automatic adjustment of the pulse frequency from 600 Hz to 1150 Hz and consequently an increase of the average power from 110 to 270 W. Hf-N films deposited using peak current regulation exhibited a stable stoichiometry, a nearly constant power-normalized deposition rate, and a polycrystalline cubic phase Hf-N with (1 1 1)-preferred orientation over the entire reactive gas flow range investigated. The physical reasons for the change in the current pulse waveform for different process conditions are discussed in some detail.

  17. Plasma Switch for High-Power Active Pulse Compressor

    SciTech Connect

    Hirshfield, Jay L.

    2013-11-04

    Results are presented from experiments carried out at the Naval Research Laboratory X-band magnicon facility on a two-channel X-band active RF pulse compressor that employed plasma switches. Experimental evidence is shown to validate the basic goals of the project, which include: simultaneous firing of plasma switches in both channels of the RF circuit, operation of quasi-optical 3-dB hybrid directional coupler coherent superposition of RF compressed pulses from both channels, and operation of the X-band magnicon directly in the RF pulse compressor. For incident 1.2 ?s pulses in the range 0.63 ? 1.35 MW, compressed pulses of peak powers 5.7 ? 11.3 MW were obtained, corresponding to peak power gain ratios of 8.3 ? 9.3. Insufficient bakeout and conditioning of the high-power RF circuit prevented experiments from being conducted at higher RF input power levels.

  18. A review comparing cathodic arcs and high power impulse magnetron sputtering (HiPIMS)

    DOE PAGES

    Anders, André

    2014-09-02

    In this study, high power impulse magnetron sputtering (HiPIMS) has been in the center of attention over the last years as it is an emerging physical vapor deposition (PVD) technology that combines advantages of magnetron sputtering with various forms of energetic deposition of films such as ion plating and cathodic arc plasma deposition. It should not come at a surprise that many extension and variations of HiPIMS make use, intentionally or unintentionally, of previously discovered approaches to film processing such as substrate surface preparation by metal ion sputtering and phased biasing for film texture and stress control. Therefore, in thismore » review, an overview is given on some historical developments and features of cathodic arc and HiPIMS plasmas, showing commonalities and differences. To limit the scope, emphasis is put on plasma properties, as opposed to surveying the vast literature on specific film materials and their properties.« less

  19. A review comparing cathodic arcs and high power impulse magnetron sputtering (HiPIMS)

    SciTech Connect

    Anders, André

    2014-09-02

    In this study, high power impulse magnetron sputtering (HiPIMS) has been in the center of attention over the last years as it is an emerging physical vapor deposition (PVD) technology that combines advantages of magnetron sputtering with various forms of energetic deposition of films such as ion plating and cathodic arc plasma deposition. It should not come at a surprise that many extension and variations of HiPIMS make use, intentionally or unintentionally, of previously discovered approaches to film processing such as substrate surface preparation by metal ion sputtering and phased biasing for film texture and stress control. Therefore, in this review, an overview is given on some historical developments and features of cathodic arc and HiPIMS plasmas, showing commonalities and differences. To limit the scope, emphasis is put on plasma properties, as opposed to surveying the vast literature on specific film materials and their properties.

  20. Active high-power RF switch and pulse compression system

    DOEpatents

    Tantawi, Sami G.; Ruth, Ronald D.; Zolotorev, Max

    1998-01-01

    A high-power RF switching device employs a semiconductor wafer positioned in the third port of a three-port RF device. A controllable source of directed energy, such as a suitable laser or electron beam, is aimed at the semiconductor material. When the source is turned on, the energy incident on the wafer induces an electron-hole plasma layer on the wafer, changing the wafer's dielectric constant, turning the third port into a termination for incident RF signals, and. causing all incident RF signals to be reflected from the surface of the wafer. The propagation constant of RF signals through port 3, therefore, can be changed by controlling the beam. By making the RF coupling to the third port as small as necessary, one can reduce the peak electric field on the unexcited silicon surface for any level of input power from port 1, thereby reducing risk of damaging the wafer by RF with high peak power. The switch is useful to the construction of an improved pulse compression system to boost the peak power of microwave tubes driving linear accelerators. In this application, the high-power RF switch is placed at the coupling iris between the charging waveguide and the resonant storage line of a pulse compression system. This optically controlled high power RF pulse compression system can handle hundreds of Megawatts of power at X-band.

  1. Physics of Plasma-Based Ion Implantation&Deposition (PBIID)and High Power Impulse Magnetron Sputtering (HIPIMS): A Comparison

    SciTech Connect

    Anders, Andre

    2007-08-28

    The emerging technology of High Power Impulse MagnetronSputtering (HIPIMS) has much in common with the more establishedtechnology of Plasma Based Ion Implantation&Deposition (PBIID):both use pulsed plasmas, the pulsed sheath periodically evolves andcollapses, the plasma-sheath system interacts with the pulse-drivingpower supply, the plasma parameters are affected by the power dissipated,surface atoms are sputtered and secondary electrons are emitted, etc.Therefore, both fields of science and technology could learn from eachother, which has not been fully explored. On the other hand, there aresignificant differences, too. Most importantly, the operation of HIPIMSheavilyrelies on the presence of a strong magnetic field, confiningelectrons and causing their ExB drift, which is closed for typicalmagnetron configurations. Second, at the high peak power levels used forHIPIMS, 1 kW/cm2 or greater averaged over the target area, the sputteredmaterial greatly affects plasma generation. For PBIID, in contrast,plasma generation and ion processing of the surface (ion implantation,etching, and deposition) are considered rela-tively independentprocesses. Third, secondary electron emission is generally considered anuisance for PBIID, especially at high voltages, whereas it is a criticalingredient to the operation of HIPIMS. Fourth, the voltages in PBIID areoften higher than in HIPIMS. For the first three reasons listed above,modelling of PBIID seems to be easier and could give some guidance forfuture HIPIMS models, which, clearly, will be more involved.

  2. Plasma relaxation mechanics of pulsed high power microwave surface flashover

    SciTech Connect

    Beeson, S.; Dickens, J.; Neuber, A.

    2013-09-15

    Microwave transmission and reflection characteristics of pulsed radio frequency field generated plasmas are elucidated for air, N{sub 2}, and He environments under pressure conditions ranging from 10 to 600 torr. The pulsed, low temperature plasma is generated along the atmospheric side of the dielectric boundary between the source (under vacuum) and the radiating environment with a thickness on the order of 5 mm and a cross sectional area just smaller than that of the waveguide. Utilizing custom multi-standard waveguide couplers and a continuous low power probing source, the scattering parameters were measured before, during, and after the high power microwave pulse with emphasis on the latter. From these scattering parameters, temporal electron density estimations (specifically the longitudinal integral of the density) were calculated using a 1D plane wave-excited model for analysis of the relaxation processes associated. These relaxation characteristics ultimately determine the maximum repetition rate for many pulsed electric field applications and thus are applicable to a much larger scope in the plasma community than just those related to high power microwaves. This manuscript discusses the diagnostic setup for acquiring the power measurements along with a detailed description of the kinematic and chemical behavior of the plasma as it decays down to its undisturbed state under various gas type and pressure conditions.

  3. Distance-dependent plasma composition and ion energy in high power impulse magnetron sputtering

    SciTech Connect

    Ehiasarian, Arutiun P; Andersson, Joakim; Anders, André

    2010-04-18

    The plasma composition of high power impulse magnetron sputtering (HIPIMS) has been studied for titanium and chromium targets using a combined energy analyser and quadrupole mass spectrometer. Measurements were done at distances from 50 to 300 mm from the sputtering target. Ti and Cr are similar in atomic mass but have significantly different sputter yields, which gives interesting clues on the effect of the target on plasma generation and transport of atoms. The Ti and Cr HIPIMS plasmas operated at a peak target current density of ~;;0.5 A cm-2. The measurements of the argon and metal ion content as well as the ion energy distribution functions showed that (1) singly and doubly charged ions were found for argon as well as for the target metal, (2) the majority of ions were singly charged argon for both metals at all distances investigated, (3) the Cr ion density was maintained to distances further from the target than Ti. Gas rarefaction was identified as a main factor promoting transport of metal ions, with the stronger effect observed for Cr, the material with higher sputter yield. Cr ions were found to displace a significant portion of the gas ions, whereas this was less evident in the Ti case. The observations indicate that the presence of metal vapour promotes charge exchange and reduces the electron temperature and thereby practically prevents the production of Ar2+ ions near the target. The content of higher charge states of metal ions depends on the probability of charge exchange with argon.

  4. A high power impulse magnetron sputtering model to explain high deposition rate magnetic field configurations

    NASA Astrophysics Data System (ADS)

    Raman, Priya; Weberski, Justin; Cheng, Matthew; Shchelkanov, Ivan; Ruzic, David N.

    2016-10-01

    High Power Impulse Magnetron Sputtering (HiPIMS) is one of the recent developments in the field of magnetron sputtering technology that is capable of producing high performance, high quality thin films. Commercial implementation of HiPIMS technology has been a huge challenge due to its lower deposition rates compared to direct current Magnetron Sputtering. The cylindrically symmetric "TriPack" magnet pack for a 10 cm sputter magnetron that was developed at the Center for Plasma Material Interactions was able to produce higher deposition rates in HiPIMS compared to conventional pack HiPIMS for the same average power. The "TriPack" magnet pack in HiPIMS produces superior substrate uniformity without the need of substrate rotation in addition to producing higher metal ion fraction to the substrate when compared to the conventional pack HiPIMS [Raman et al., Surf. Coat. Technol. 293, 10 (2016)]. The films that are deposited using the "TriPack" magnet pack have much smaller grains compared to conventional pack DC and HiPIMS films. In this paper, the reasons behind the observed increase in HiPIMS deposition rates from the TriPack magnet pack along with a modified particle flux model is discussed.

  5. Particle visualization in high-power impulse magnetron sputtering. I. 2D density mapping

    SciTech Connect

    Britun, Nikolay Palmucci, Maria; Konstantinidis, Stephanos; Snyders, Rony

    2015-04-28

    Time-resolved characterization of an Ar-Ti high-power impulse magnetron sputtering discharge has been performed. This paper deals with two-dimensional density mapping in the discharge volume obtained by laser-induced fluorescence imaging. The time-resolved density evolution of Ti neutrals, singly ionized Ti atoms (Ti{sup +}), and Ar metastable atoms (Ar{sup met}) in the area above the sputtered cathode is mapped for the first time in this type of discharges. The energetic characteristics of the discharge species are additionally studied by Doppler-shift laser-induced fluorescence imaging. The questions related to the propagation of both the neutral and ionized discharge particles, as well as to their spatial density distributions, are discussed.

  6. Innovation on high-power long-pulse gyrotrons

    NASA Astrophysics Data System (ADS)

    Litvak, Alexander; Sakamoto, Keishi; Thumm, Manfred

    2011-12-01

    Progress in the worldwide development of high-power gyrotrons for magnetic confinement fusion plasma applications is described. After technology breakthroughs in research on gyrotron components in the 1990s, significant progress has been achieved in the last decade, in particular, in the field of long-pulse and continuous wave (CW) gyrotrons for a wide range of frequencies. At present, the development of 1 MW-class CW gyrotrons has been very successful; these are applicable for self-ignition experiments on fusion plasmas and their confinement in the tokamak ITER, for long-pulse confinement experiments in the stellarator Wendelstein 7-X (W7-X) and for EC H&CD in the future tokamak JT-60SA. For this progress in the field of high-power long-pulse gyrotrons, innovations such as the realization of high-efficiency stable oscillation in very high order cavity modes, the use of single-stage depressed collectors for energy recovery, highly efficient internal quasi-optical mode converters and synthetic diamond windows have essentially contributed. The total tube efficiencies are around 50% and the purity of the fundamental Gaussian output mode is 97% and higher. In addition, activities for advanced gyrotrons, e.g. a 2 MW gyrotron using a coaxial cavity, multi-frequency 1 MW gyrotrons and power modulation technology, have made progress.

  7. Spectroscopic imaging of self-organization in high power impulse magnetron sputtering plasmas

    SciTech Connect

    Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore, Singapore; Andersson, Joakim; Ni, Pavel; Anders, Andre

    2013-07-17

    Excitation and ionization conditions in traveling ionization zones of high power impulse magnetron sputtering plasmas were investigated using fast camera imaging through interference filters. The images, taken in end-on and side on views using light of selected gas and target atom and ion spectral lines, suggest that ionization zones are regions of enhanced densities of electrons, and excited atoms and ions. Excited atoms and ions of the target material (Al) are strongly concentrated near the target surface. Images from the highest excitation energies exhibit the most localized regions, suggesting localized Ohmic heating consistent with double layer formation.

  8. Ion energies in high power impulse magnetron sputtering with and without localized ionization zones

    SciTech Connect

    Yang, Yuchen; Tanaka, Koichi; Liu, Jason; Anders, André

    2015-03-23

    High speed imaging of high power impulse magnetron sputtering discharges has revealed that ionization is localized in moving ionization zones but localization disappears at high currents for high yield targets. This offers an opportunity to study the effect ionization zones have on ion energies. We measure that ions have generally higher energies when ionization zones are present, supporting the concept that these zones are associated with moving potential humps. We propose that the disappearance of ionization zones is caused by an increased supply of atoms from the target which cools electrons and reduces depletion of atoms to be ionized.

  9. Drifting potential humps in ionization zones: The ``propeller blades'' of high power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Anders, André; Panjan, Matjaž; Franz, Robert; Andersson, Joakim; Ni, Pavel

    2013-09-01

    Ion energy distribution functions measured for high power impulse magnetron sputtering show features, such as a broad peak at several 10 eV with an extended tail, as well as asymmetry with respect to E ×B, where E and B are the local electric and magnetic field vectors, respectively. Here it is proposed that those features are due to the formation of a potential hump of several 10 V in each of the traveling ionization zones. Potential hump formation is associated with a negative-positive-negative space charge that naturally forms in ionization zones driven by energetic drifting electrons.

  10. An explosively driven high-power microwave pulsed power system

    NASA Astrophysics Data System (ADS)

    Elsayed, M. A.; Neuber, A. A.; Dickens, J. C.; Walter, J. W.; Kristiansen, M.; Altgilbers, L. L.

    2012-02-01

    The increased popularity of high power microwave systems and the various sources to drive them is the motivation behind the work to be presented. A stand-alone, self-contained explosively driven high power microwave pulsed power system has been designed, built, and tested at Texas Tech University's Center for Pulsed Power and Power Electronics. The system integrates four different sub-units that are composed of a battery driven prime power source utilizing capacitive energy storage, a dual stage helical flux compression generator as the main energy amplification device, an integrated power conditioning system with inductive energy storage including a fast opening electro-explosive switch, and a triode reflex geometry virtual cathode oscillator as the microwave radiating source. This system has displayed a measured electrical source power level of over 5 GW and peak radiated microwaves of about 200 MW. It is contained within a 15 cm diameter housing and measures 2 m in length, giving a housing volume of slightly less than 39 l. The system and its sub-components have been extensively studied, both as integrated and individual units, to further expand on components behavior and operation physics. This report will serve as a detailed design overview of each of the four subcomponents and provide detailed analysis of the overall system performance and benchmarks.

  11. Influence of high power impulse magnetron sputtering plasma ionization on the microstructure of TiN thin films

    NASA Astrophysics Data System (ADS)

    Ehiasarian, A. P.; Vetushka, A.; Gonzalvo, Y. Aranda; Sáfrán, G.; Székely, L.; Barna, P. B.

    2011-05-01

    HIPIMS (High Power Impulse Magnetron Sputtering) discharge is a new PVD technology for the deposition of high-quality thin films. The deposition flux contains a high degree of metal ionization and nitrogen dissociation. The microstructure of HIPIMS-deposited nitride films is denser compared to conventional sputter technologies. However, the mechanisms acting on the microstructure, texture and properties have not been discussed in detail so far. In this study, the growth of TiN by HIPIMS of Ti in mixed Ar and N2 atmosphere has been investigated. Varying degrees of metal ionization and nitrogen dissociation were produced by increasing the peak discharge current (Id) from 5 to 30 A. The average power was maintained constant by adjusting the frequency. Mass spectrometry measurements of the deposition flux revealed a high content of ionized film-forming species, such as Ti1+, Ti2+ and atomic nitrogen N1+. Ti1+ ions with energies up to 50 eV were detected during the pulse with reducing energy in the pulse-off times. Langmuir probe measurements showed that the peak plasma density during the pulse was 3 × 1016 m-3. Plasma density, and ion flux ratios of N1+: N21+ and Ti1+: Ti0 increased linearly with peak current. The ratios exceeded 1 at 30 A. TiN films deposited by HIPIMS were analyzed by X-ray diffraction, and transmission electron microscopy. At high Id, N1+: N21+> 1 and Ti1+: Ti0> 1 were produced; a strong 002 texture was present and column boundaries in the films were atomically tight. As Id reduced and N1+: N21+ and Ti1+: Ti0 dropped below 1, the film texture switched to strong 111 with a dense structure. At very low Id, porosity between columns developed. The effects of the significant activation of the deposition flux observed in the HIPIMS discharge on the film texture, microstructure, morphology and properties are discussed.

  12. Investigation of a high power electromagnetic pulse source.

    PubMed

    Wang, Yuwei; Chen, Dongqun; Zhang, Jiande; Cao, Shengguang; Li, Da; Liu, Chebo

    2012-09-01

    A high power electromagnetic pulse source with a resonant antenna driven by a compact power supply was investigated in this paper. To match the impedance of the resonant antenna and initial power source, a compact power conditioning circuit based on electro exploding opening switch (EEOS) and pulsed transformer was adopted. In the preliminary experiments, an impulse capacitor was used to drive the system. With the opening of the EEOS at the current of 15 kA flowing trough the primary of the transformer, the resonant antenna was rapidly charged to about -370 kV within a time of about 100 ns. When the switch in the resonant antenna closed at the charging voltage of about -202 kV, the peak intensity of the detected electric field at a distance of about 10 m from the center of the source was 7.2 kV∕m. The corresponding peak power of the radiated electromagnetic field reached 76 MW, while the total radiated electromagnetic energy was about 0.65 J. The total energy efficiency of the resonant antenna was about 22% which can be improved by increasing the closing rapidity of the switch in the antenna.

  13. High power linear pulsed beam annealer. [Patent application

    DOEpatents

    Strathman, M.D.; Sadana, D.K.; True, R.B.

    1980-11-26

    A high power pulsed electron beam system for annealing semiconductors is comprised of an electron gun having a heated cathode, control grid and focus ring for confining the pulsed beam of electrons to a predetermined area, and a curved drift tube. The drift tube and an annular Faraday shield between the focus ring and the drift tube are maintained at a high positive voltage with respect to the cathode to accelerate electrons passing through the focus ring, thereby eliminating space charge limitations on the emission of electrons from said gun. A coil surrounding the curved drift tube provides a magnetic field which maintains the electron beam focused about the axis of the tube. The magnetic field produced by the coil around the curved tube imparts motion to electrons in a spiral path for shallow penetration of the electrons into a target. It also produces a scalloped profile of the electron beam. A second drift tube spaced a predetermined distance from the curved tube is positioned with its axis aligned with the axis of the first drift tube. The second drift tube and the target holder are maintained at a reference voltage between the cathode voltage and the curved tube voltage to decelerate the electrons. A second coil surrounding the second drift tube, maintains the electron beam focused about the axis of the second drift tube. The magnetic field of the second coil comprises the electron beam to the area of the semiconductor on the target holder.

  14. Particle visualization in high-power impulse magnetron sputtering. II. Absolute density dynamics

    SciTech Connect

    Britun, Nikolay Palmucci, Maria; Konstantinidis, Stephanos; Snyders, Rony

    2015-04-28

    Time-resolved characterization of an Ar-Ti high-power impulse magnetron sputtering discharge has been performed. The present, second, paper of the study is related to the discharge characterization in terms of the absolute density of species using resonant absorption spectroscopy. The results on the time-resolved density evolution of the neutral and singly-ionized Ti ground state atoms as well as the metastable Ti and Ar atoms during the discharge on- and off-time are presented. Among the others, the questions related to the inversion of population of the Ti energy sublevels, as well as to re-normalization of the two-dimensional density maps in terms of the absolute density of species, are stressed.

  15. Perspective: Is there a hysteresis during reactive High Power Impulse Magnetron Sputtering (R-HiPIMS)?

    NASA Astrophysics Data System (ADS)

    Strijckmans, K.; Moens, F.; Depla, D.

    2017-02-01

    This paper discusses a few mechanisms that can assist to answer the title question. The initial approach is to use an established model for DC magnetron sputter deposition, i.e., RSD2013. Based on this model, the impact on the hysteresis behaviour of some typical HiPIMS conditions is investigated. From this first study, it becomes clear that the probability to observe hysteresis is much lower as compared to DC magnetron sputtering. The high current pulses cannot explain the hysteresis reduction. Total pressure and material choice make the abrupt changes less pronounced, but the implantation of ionized metal atoms that return to the target seems to be the major cause. To further substantiate these results, the analytical reactive sputtering model is coupled with a published global plasma model. The effect of metal ion implantation is confirmed. Another suggested mechanism, i.e., gas rarefaction, can be ruled out to explain the hysteresis reduction. But perhaps the major conclusion is that at present, there are too little experimental data available to make fully sound conclusions.

  16. Novel high power impulse magnetron sputtering enhanced by an auxiliary electrical field.

    PubMed

    Li, Chunwei; Tian, Xiubo

    2016-08-01

    The high power impulse magnetron sputtering (HIPIMS) technique is a novel highly ionized physical vapor deposition method with a high application potential. However, the electron utilization efficiency during sputtering is rather low and the metal particle ionization rate needs to be considerably improved to allow for a large-scale industrial application. Therefore, we enhanced the HIPIMS technique by simultaneously applying an electric field (EF-HIPIMS). The effect of the electric field on the discharge process was studied using a current sensor and an optical emission spectrometer. Furthermore, the spatial distribution of the electric potential and electric field during the EF-HIPIMS process was simulated using the ANSYS software. The results indicate that a higher electron utilization efficiency and a higher particle ionization rate could be achieved. The auxiliary anode obviously changed the distribution of the electric potential and the electric field in the discharge region, which increased the plasma density and enhanced the degree of ionization of the vanadium and argon gas. Vanadium films were deposited to further compare both techniques, and the morphology of the prepared films was investigated by scanning electron microscopy. The films showed a smaller crystal grain size and a denser growth structure when the electric field was applied during the discharge process.

  17. Codeposition of amorphous zinc tin oxide using high power impulse magnetron sputtering: characterisation and doping

    NASA Astrophysics Data System (ADS)

    Tran, H. N.; Mayes, E. L. H.; Murdoch, B. J.; McCulloch, D. G.; McKenzie, D. R.; Bilek, M. M. M.; Holland, A. S.; Partridge, J. G.

    2017-04-01

    Thin film zinc tin oxide (ZTO) has been energetically deposited at 100 °C using high power impulse magnetron sputtering (HiPIMS). Reactive co-deposition from Zn (HiPIMS mode) and Sn (DC magnetron sputtering mode) targets yielded a gradient in the Zn:Sn ratio across a 4-inch diameter sapphire substrate. The electrical and optical properties of the film were studied as a function of composition. As-deposited, the films were amorphous, transparent and semi-insulating. Hydrogen was introduced by post-deposition annealing (1 h, 500 °C, 100 mTorr H2) and resulted in significantly increased conductivity with no measurable structural alterations. After annealing, Hall effect measurements revealed n-type carrier concentrations of ∼1 × 1017 cm‑3 and mobilities of up to 13 cm2 V‑1 s–1. These characteristics are suitable for device applications and proved stable. X-ray photoelectron spectroscopy was used to explore the valence band structure and to show that downward surface band-bending resulted from OH attachment. The results suggest that HiPIMS can produce dense, high quality amorphous ZTO suitable for applications including transparent thin film transistors.

  18. Novel high power impulse magnetron sputtering enhanced by an auxiliary electrical field

    NASA Astrophysics Data System (ADS)

    Li, Chunwei; Tian, Xiubo

    2016-08-01

    The high power impulse magnetron sputtering (HIPIMS) technique is a novel highly ionized physical vapor deposition method with a high application potential. However, the electron utilization efficiency during sputtering is rather low and the metal particle ionization rate needs to be considerably improved to allow for a large-scale industrial application. Therefore, we enhanced the HIPIMS technique by simultaneously applying an electric field (EF-HIPIMS). The effect of the electric field on the discharge process was studied using a current sensor and an optical emission spectrometer. Furthermore, the spatial distribution of the electric potential and electric field during the EF-HIPIMS process was simulated using the ANSYS software. The results indicate that a higher electron utilization efficiency and a higher particle ionization rate could be achieved. The auxiliary anode obviously changed the distribution of the electric potential and the electric field in the discharge region, which increased the plasma density and enhanced the degree of ionization of the vanadium and argon gas. Vanadium films were deposited to further compare both techniques, and the morphology of the prepared films was investigated by scanning electron microscopy. The films showed a smaller crystal grain size and a denser growth structure when the electric field was applied during the discharge process.

  19. ZrN coatings deposited by high power impulse magnetron sputtering and cathodic arc techniques

    SciTech Connect

    Purandare, Yashodhan Ehiasarian, Arutiun; Hovsepian, Papken; Santana, Antonio

    2014-05-15

    Zirconium nitride (ZrN) coatings were deposited on 1 μm finish high speed steel and 316L stainless steel test coupons. Cathodic Arc (CA) and High Power Impulse Magnetron Sputtering (HIPIMS) + Unbalanced Magnetron Sputtering (UBM) techniques were utilized to deposit coatings. CA plasmas are known to be rich in metal and gas ions of the depositing species as well as macroparticles (droplets) emitted from the arc sports. Combining HIPIMS technique with UBM in the same deposition process facilitated increased ion bombardment on the depositing species during coating growth maintaining high deposition rate. Prior to coating deposition, substrates were pretreated with Zr{sup +} rich plasma, for both arc deposited and HIPIMS deposited coatings, which led to a very high scratch adhesion value (L{sub C2}) of 100 N. Characterization results revealed the overall thickness of the coatings in the range of 2.5 μm with hardness in the range of 30–40 GPa depending on the deposition technique. Cross-sectional transmission electron microscopy and tribological experiments such as dry sliding wear tests and corrosion studies have been utilized to study the effects of ion bombardment on the structure and properties of these coatings. In all the cases, HIPIMS assisted UBM deposited coating fared equal or better than the arc deposited coatings, the reasons being discussed in this paper. Thus H+U coatings provide a good alternative to arc deposited where smooth, dense coatings are required and macrodroplets cannot be tolerated.

  20. System for time-resolved laser absorption spectroscopy and its application to high-power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Adámek, P.; Olejníček, J.; Hubička, Z.; Čada, M.; Kment, Š.; Kohout, M.; Do, H. T.

    2017-02-01

    This paper deals with the development and construction of an apparatus for time-resolved tunable diode laser absorption spectroscopy (LAS) for the diagnostics of pulsed plasma. A detailed description of the extension of a progressive method of laser absorption spectroscopy in continuous regime to a direct triggering method of the time-resolved laser absorption spectroscopy (TR-LAS) is presented. The main advantage of the developed method is its capability to measure the time evolution of the whole absorption profile with a preset time resolution, which can be less than 1 μs. Therefore, the presented method of repetitive sampling applied on LAS in plasma processes is capable of simultaneous measurement of the density and kinetic temperature of selected particles. Its appropriate applications are to periodical processes in technological plasma, namely pulsed plasma discharges. The developed method of TR-LAS was applied to measurements of the temporal evolution of density and kinetic temperature of argon metastable species during high-power impulse magnetron sputtering of titanium and titanium dioxide thin films.

  1. System for time-resolved laser absorption spectroscopy and its application to high-power impulse magnetron sputtering.

    PubMed

    Adámek, P; Olejníček, J; Hubička, Z; Čada, M; Kment, Š; Kohout, M; Do, H T

    2017-02-01

    This paper deals with the development and construction of an apparatus for time-resolved tunable diode laser absorption spectroscopy (LAS) for the diagnostics of pulsed plasma. A detailed description of the extension of a progressive method of laser absorption spectroscopy in continuous regime to a direct triggering method of the time-resolved laser absorption spectroscopy (TR-LAS) is presented. The main advantage of the developed method is its capability to measure the time evolution of the whole absorption profile with a preset time resolution, which can be less than 1 μs. Therefore, the presented method of repetitive sampling applied on LAS in plasma processes is capable of simultaneous measurement of the density and kinetic temperature of selected particles. Its appropriate applications are to periodical processes in technological plasma, namely pulsed plasma discharges. The developed method of TR-LAS was applied to measurements of the temporal evolution of density and kinetic temperature of argon metastable species during high-power impulse magnetron sputtering of titanium and titanium dioxide thin films.

  2. The use of segmented cathodes to determine the spoke current density distribution in high power impulse magnetron sputtering plasmas

    SciTech Connect

    Poolcharuansin, Phitsanu; Estrin, Francis Lockwood; Bradley, James W.

    2015-04-28

    The localized target current density associated with quasi-periodic ionization zones (spokes) has been measured in a high power impulse magnetron sputtering (HiPIMS) discharge using an array of azimuthally separated and electrical isolated probes incorporated into a circular aluminum target. For a particular range of operating conditions (pulse energies up to 2.2 J and argon pressures from 0.2 to 1.9 Pa), strong oscillations in the probe current density are seen with amplitudes up to 52% above a base value. These perturbations, identified as spokes, travel around the discharge above the target in the E×B direction. Using phase information from the angularly separated probes, the spoke drift speeds, angular frequencies, and mode number have been determined. Generally, at low HiPIMS pulse energies E{sub p} < 0.8 J, spokes appear to be chaotic in nature (with random arrival times), however as E{sub p} increases, coherent spokes are observed with velocities between 6.5 and 10 km s{sup −1} and mode numbers m = 3 or above. At E{sub p} > 1.8 J, the plasma becomes spoke-free. The boundaries between chaotic, coherent, and no-spoke regions are weakly dependent on pressure. During each HiPIMS pulse, the spoke velocities increase by about 50%. Such an observation is explained by considering spoke velocities to be determined by the critical ionization velocity, which changes as the plasma composition changes during the pulse. From the shape of individual current density oscillations, it appears that the leading edge of the spoke is associated with a slow increase in local current density to the target and the rear with a more rapid decrease. The measurements show that the discharge current density associated with individual spokes is broadly spread over a wide region of the target.

  3. Downstream plasma transport and metal ionization in a high-powered pulsed-plasma magnetron

    NASA Astrophysics Data System (ADS)

    Meng, Liang; Yu, He; Szott, Matthew M.; McLain, Jake T.; Ruzic, David N.

    2014-06-01

    Downstream plasma transport and ionization processes in a high-powered pulsed-plasma magnetron were studied. The temporal evolution and spatial distribution of electron density (ne) and temperature (Te) were characterized with a 3D scanning triple Langmuir probe. Plasma expanded from the racetrack region into the downstream region, where a high ne peak was formed some time into the pulse-off period. The expansion speed and directionality towards the substrate increased with a stronger magnetic field (B), largely as a consequence of a larger potential drop in the bulk plasma region during a relatively slower sheath formation. The fraction of Cu ions in the deposition flux was measured on the substrate using a gridded energy analyzer. It increased with higher pulse voltage. With increased B field from 200 to 800 Gauss above racetrack, ne increased but the Cu ion fraction decreased from 42% to 16%. A comprehensive model was built, including the diffusion of as-sputtered Cu flux, the Cu ionization in the entire plasma region using the mapped ne and Te data, and ion extraction efficiency based on the measured plasma potential (Vp) distribution. The calculations matched the measurements and indicated the main causes of lower Cu ion fractions in stronger B fields to be the lower Te and inefficient ion extraction in a larger pre-sheath potential.

  4. Enhancement of bioactivity on medical polymer surface using high power impulse magnetron sputtered titanium dioxide film.

    PubMed

    Yang, Yi-Ju; Tsou, Hsi-Kai; Chen, Ying-Hung; Chung, Chi-Jen; He, Ju-Liang

    2015-12-01

    This study utilizes a novel technique, high power impulse magnetron sputtering (HIPIMS), which provides a higher ionization rate and ion bombardment energy than direct current magnetron sputtering (DCMS), to deposit high osteoblast compatible titanium dioxide (TiO2) coatings with anatase (A-TiO2) and rutile (R-TiO2) phases onto the biomedical polyetheretherketone (PEEK) polymer substrates at low temperature. The adhesions of TiO2 coatings that were fabricated using HIPIMS and DCMS were compared. The in vitro biocompatibility of these coatings was confirmed. The results reveal that HIPIMS can be used to prepare crystallinic columnar A-TiO2 and R-TiO2 coatings on PEEK substrate if the ratio of oxygen to argon is properly controlled. According to a tape adhesion test, the HIPIMS-TiO2 coatings had an adhesion grade of 5B even after they were immersed in simulated body fluid (SBF) environments for 28days. Scratch tests proved that HIPIMS-TiO2 coatings undergo cohesive failure. These results demonstrate that the adhesive force between HIPIMS-TiO2 coating/PEEK is stronger than that between DCMS-TiO2 coating/PEEK. After a long period (28days) of immersion in SBF, a bone-like crystallinic hydroxyapatite layer with a corresponding Ca/P stoichiometry was formed on both HIPIMS-TiO2. The osteoblast compatibility of HIPIMS-TiO2 exceeded that of the bare PEEK substrate. It is also noticeable that the R-TiO2 performed better in vitro than the A-TiO2 due to the formation of many negatively charged hydroxyl groups (-OH(-)) groups on R-TiO2 (110) surface. In summary, the HIPIMS-TiO2 coatings satisfied the requirements for osseointegration, suggesting the possibility of using HIPIMS to modify the PEEK surface with TiO2 for spinal implants.

  5. Localized traveling ionization zones and their importance for the high power impulse magnetron sputtering process

    NASA Astrophysics Data System (ADS)

    Maszl, Christian

    2016-09-01

    High power impulse magnetron sputtering (HiPIMS) is a technique to deposit thin films with superior quality. A high ionization degree up to 90% and the natural occurence of high energetic metal ions are the reason why HiPIMS exceeds direct current magnetron sputtering in terms of coating quality. On the other hand HiPIMS suffers from a reduced efficiency, especially if metal films are produced. Therefore, a lot of research is done by experimentalists and theoreticians to clarify the transport mechanisms from target to substrate and to identify the energy source of the energetic metal ions. Magnetron plasmas are prone to a wide range of wave phenomena and instabilities. Especially, during HiPIMS at elevated power/current densities, symmetry breaks and self-organization in the plasma torus are observed. In this scenario localized travelling ionization zones with certain quasi-mode numbers are present which are commonly referred to as spokes. Because of their high rotation speed compared to typical process times of minutes their importance for thin film deposition was underestimated at first. Recent investigations show that spokes have a strong impact on particle transport, are probably the source of the high energetic metal ions and are therefore the essence of HiPIMS plasmas. In this contribution we will describe the current understanding of spokes, discuss implications for thin film synthesis and highlight open questions. This project is supported by the DFG (German Science Foundation) within the framework of the Coordinated Research Center SFB-TR 87 and the Research Department ``Plasmas with Complex Interactions'' at Ruhr-University Bochum.

  6. From the electromagnetic pulse to high-power electromagnetics

    NASA Astrophysics Data System (ADS)

    Baum, Carl E.

    1992-06-01

    This paper updates the published literature of the late 1970's concerning the development of requisite technology for the nuclear EMP. EMP has impacted a set of related areas that can be collectively referred to as high-power electromagnetics. This includes high-power microwaves, direct-strike lightning, and some aspects of transient radar.

  7. Influence of high power impulse magnetron sputtering plasma ionization on the microstructure of TiN thin films

    SciTech Connect

    Ehiasarian, A. P.; Vetushka, A.; Gonzalvo, Y. Aranda; Safran, G.; Szekely, L.; Barna, P. B.

    2011-05-15

    HIPIMS (High Power Impulse Magnetron Sputtering) discharge is a new PVD technology for the deposition of high-quality thin films. The deposition flux contains a high degree of metal ionization and nitrogen dissociation. The microstructure of HIPIMS-deposited nitride films is denser compared to conventional sputter technologies. However, the mechanisms acting on the microstructure, texture and properties have not been discussed in detail so far. In this study, the growth of TiN by HIPIMS of Ti in mixed Ar and N{sub 2} atmosphere has been investigated. Varying degrees of metal ionization and nitrogen dissociation were produced by increasing the peak discharge current (I{sub d}) from 5 to 30 A. The average power was maintained constant by adjusting the frequency. Mass spectrometry measurements of the deposition flux revealed a high content of ionized film-forming species, such as Ti{sup 1+}, Ti{sup 2+} and atomic nitrogen N{sup 1+}. Ti{sup 1+} ions with energies up to 50 eV were detected during the pulse with reducing energy in the pulse-off times. Langmuir probe measurements showed that the peak plasma density during the pulse was 3 x 10{sup 16} m{sup -3}. Plasma density, and ion flux ratios of N{sup 1+}: N{sub 2}{sup 1+} and Ti{sup 1+}: Ti{sup 0} increased linearly with peak current. The ratios exceeded 1 at 30 A. TiN films deposited by HIPIMS were analyzed by X-ray diffraction, and transmission electron microscopy. At high I{sub d}, N{sup 1+}: N{sub 2}{sup 1+} > 1 and Ti{sup 1+}: Ti{sup 0} > 1 were produced; a strong 002 texture was present and column boundaries in the films were atomically tight. As I{sub d} reduced and N{sup 1+}: N{sub 2}{sup 1+} and Ti{sup 1+}: Ti{sup 0} dropped below 1, the film texture switched to strong 111 with a dense structure. At very low I{sub d}, porosity between columns developed. The effects of the significant activation of the deposition flux observed in the HIPIMS discharge on the film texture, microstructure, morphology and

  8. Formation of hydrogenated amorphous carbon films by reactive high power impulse magnetron sputtering containing C2H2 gas

    NASA Astrophysics Data System (ADS)

    Kimura, Takashi; Kamata, Hikaru

    2015-09-01

    Diamond-like carbon (DLC) films have attracted interest for material industries, because they have unique properties. Hydrogenated amorphous carbon films are prepared by reactive high power impulse magnetron sputtering (HiPIMS) containing C2H2 gas and the properties of the films produced in Ar/C2H2 and Ne/C2H2 HiPIMS are compared. Production of hydrocarbon radicals and their ions strongly depends on both electron temperature and electron density in HiPIMS. Therefore, the influence of the difference in buffer gas (Ar and Ne) on the film properties is also valuable to investigate. The film preparation is performed at an average power of 60 W and a repetition frequency of 110 Hz. Total pressure ranges between 0.3 and 2 Pa. The maximum of instantaneous power is about 20-25 kW, and the magnitude of the current is 35 A. A negative pulse voltage is applied to the substrates for about 15 μs after the target voltage changed from about -500 V to 0 V. Hardness of the films prepared by Ar/C2H2 HiPIMS monotonically decreases with increasing the total pressure, whereas that of the films prepared by Ne/C2H2 HiPIMS does not strongly depend on the total pressure. This work is partially supported by JSPS KAKENHI Grant Number 26420230.

  9. Species transport on the target during high power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Layes, V.; Monje, S.; Corbella, C.; Trieschmann, J.; de los Arcos, T.; von Keudell, A.

    2017-02-01

    High Power Impulse Magnetron Sputtering (HiPIMS) is a prominent technique to deposit superior materials due to the very energetic growth flux. The origin of this energetic growth flux is believed to be an electric potential structure inside localized ionization zones, the so-called spokes, in the HiPIMS plasma, which rotate in the E × B direction along the racetrack. The measurement of this electric potential or of the electric fields surrounding this ionization zone is extremely challenging due to the very high local power density that obstructs any traditional probe diagnostics. Here, we use a marker technique on the magnetron target to analyze the lateral transport of a target material on a HiPIMS target. We show that the target material is predominantly transported in the E × B direction irrespective of the presence of spokes. However, only when spokes are present, we observe also an enhanced transport in the opposite E × B direction. This is explained by the large electric field at the trailing edges of spokes.

  10. The behaviour of arcs in carbon mixed-mode high-power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Tucker, M. D.; Putman, K. J.; Ganesan, R.; Lattemann, M.; Stueber, M.; Ulrich, S.; Bilek, M. M. M.; McKenzie, D. R.; Marks, N. A.

    2017-04-01

    Mixed-mode deposition of carbon is an extension of high-power impulse magnetron sputtering in which a short-lived arc is deliberately allowed to ignite on the target surface to increase the ionised fraction of carbon in the deposition flux. Here we investigate the ignition and evolution of these arcs and examine their behaviour for different conditions of argon pressure, power supply voltage, and current. We find that mixed-mode deposition is sensitive to the condition of the target surface, and changing the operating parameters causes changes in the target surface condition which themselves affect the discharge in a process of negative feedback. Initially the arcs are evenly distributed on the target racetrack, but after a long period of operation the mode of erosion changes and arcs become localised in a small region, resulting in a pronounced nodular structure. We also quantify macroparticle generation and observe a power-law size distribution typical of arc discharges. Fewer particles are generated for operation at lower Ar pressure when the arc spot velocity is higher.

  11. Antimicrobial brass coatings prepared on poly(ethylene terephthalate) textile by high power impulse magnetron sputtering.

    PubMed

    Chen, Ying-Hung; Wu, Guo-Wei; He, Ju-Liang

    2015-03-01

    The goal of this work is to prepare antimicrobial, corrosion-resistant and low-cost Cu65Zn35 brass film on poly(ethylene terephthalate) (PET) fabric by high-power impulse magnetron sputtering (HIPIMS), which is known to provide high-density plasma, so as to generate a strongly adherent film at a reduced substrate temperature. The results reveal that the brass film grows in a layer-plus-island mode. Independent of their deposition time, the obtained films retain a Cu/Zn elemental composition ratio of 1.86 and exhibit primarily an α copper phase structure. Oxygen plasma pre-treatment for 1min before coating can significantly increase film adhesion such that the brass-coated fabric of Grade 5 or Grade 4-5 can ultimately be obtained under dry and wet rubbing tests, respectively. However, a deposition time of 1min suffices to provide effective antimicrobial properties for both Staphylococcus aureus and Escherichia coli. As a whole, the feasibility of using such advanced HIPIMS coating technique to develop durable antimicrobial textile was demonstrated.

  12. High-Power Picosecond Pulse Recirculation for Inverse Compton Scattering

    NASA Astrophysics Data System (ADS)

    Jovanovic, Igor; Shverdin, Miro; Gibson, David; Brown, Curtis; Gronberg, Jeff

    2008-11-01

    In the next generation of linear colliders, inverse Compton scattering (ICS) of intense laser pulses on relativistic electron bunches will enable a mode of operation based on energetic γe and γγ collisions, with a significant complementary scientific potential. The efficiency of γ-ray generation via ICS is constrained by the Thomson scattering cross section, resulting in typical laser photon-to- γ efficiencies of <10 -9. Furthermore, repetition rates of the state-of-art high-energy short-pulse lasers are poorly matched with those available from electron accelerators. Laser recirculation has been proposed as a method to address those limitations, but has been limited to only small pulse energies and peak powers. We propose and experimentally demonstrate an alternative, non-interferometric method for laser pulse recirculation that is uniquely capable of recirculating short pulses with energies exceeding 1 J [ I. Jovanovic, M. Shverdin, D. Gibson, and C. Brown, Nucl. Instrum. Methods A 578 160 (2007)]. ICS of recirculated Joule-level laser pulses is compatible with the proposed pulse structure for ILC and has a potential to produce unprecedented peak and average γ-ray brightness in the next generation of sources.

  13. Radio-frequency plasma cleaning for mitigation of high-power microwave-pulse shortening in a coaxial gyrotron

    NASA Astrophysics Data System (ADS)

    Cohen, William E.; Gilgenbach, Ronald M.; Jaynes, Reginald L.; Peters, Christopher W.; Lopez, Mike R.; Lau, Y. Y.; Anderson, Scott A.; Brake, Mary L.; Spencer, Thomas A.

    2000-12-01

    Results are reported demonstrating that radio-frequency (rf) plasma cleaning is an effective technique for mitigating microwave-pulse shortening (i.e., lengthening the pulse) in a multimegawatt, large-orbit, coaxial gyrotron. Cleaning plasmas were generated by 50 W of rf power at 13.56 MHz in nitrogen fill gas in the pressure range 15-25 mTorr. Improvements in the averaged microwave energy output of this high-power-microwave device ranged from 15% to 245% for different initial conditions and cleaning protocols. The mechanism for this improvement is believed to be rf plasma sputtering of excess water vapor from the cavity/waveguide and subsequent removal of the contaminant by cryogenic vacuum pumps.

  14. Detection of nanosecond-scale, high power THz pulses with a field effect transistor

    SciTech Connect

    Preu, S.; Lu, H.; Gossard, A. C.; Sherwin, M. S.

    2012-05-15

    We demonstrate detection and resolution of high power, 34 ns free electron laser pulses using a rectifying field effect transistor. The detector remains linear up to an input power of 11 {+-} 0.5 W at a pulse energy of 20 {+-} 1 {mu}J at 240 GHz. We compare its performance to a protected Schottky diode, finding a shorter intrinsic time constant. The damage threshold is estimated to be a few 100 W. The detector is, therefore, well-suited for characterizing high power THz pulses. We further demonstrate that the same detector can be used to detect low power continuous-wave THz signals with a post detection limited noise floor of 3.1 {mu}W/{radical}(Hz). Such ultrafast, high power detectors are important tools for high power and high energy THz facilities such as free electron lasers.

  15. High-power pulsed 976-nm DFB laser diodes

    NASA Astrophysics Data System (ADS)

    Zeller, Wolfgang; Kamp, Martin; Koeth, Johannes; Worschech, Lukas

    2010-04-01

    Distributed feedback (DFB) laser diodes nowadays provide stable single mode emission for many different applications covering a wide wavelength range. The available output power is usually limited because of catastrophical optical mirror damage (COD) caused by the small facet area. For some applications such as trace gas detection output powers of several ten milliwatts are sufficiently high, other applications like distance measurement or sensing in harsh environments however require much higher output power levels. We present a process combining optimizations of the layer structure with a new lateral design of the ridge waveguide which is fully compatible with standard coating and passivation processes. By implementing a large optical cavity with the active layer positioned not in the middle of the waveguide layers but very close to the upper edge, the lasers' farfield angles can be drastically reduced. Furthermore, the travelling light mode can be pushed down into the large optical cavity by continuously decreasing the ridge waveguide width towards both laser facets. The light mode then spreads over a much larger area, thus reducing the surface power density which leads to significantly higher COD thresholds. Laterally coupled DFB lasers based on this concept emitting at wavelengths around 976 nm yield hitherto unachievable COD thresholds of 1.6 W under pulsed operation. The high mode stability during the 50 ns pulses means such lasers are ideally suited for high precision distance measurement or similar tasks.

  16. Generation of high-power nanosecond pulses from laser diode-pumped Nd:YAG lasers

    NASA Technical Reports Server (NTRS)

    Chan, Kinpui

    1988-01-01

    Simulation results are used to compare the pulse energy levels and pulse energy widths that can be achieved with LD-pumped Nd:YAG lasers for both the pulse-transmission mode (PTM) and pulse-reflection mode (PRM) Q-switching methods for pulse energy levels up to hundreds of microjoules and pulse widths as short as 1 ns. It is shown that high-power pulses with pulse widths as short as 1 ns can be generated with PTM Q-switched in LD-pumped Nd:YAG lasers. With the PRM Q-switching method, pulse widths as short as 2 ns and pulse energy at the level of a few hundred microjoules can also be achieved but require pumping with 8-10-mJ AlGaAs laser diode arrays.

  17. High power double-scale pulses from a gain-guided double-clad fiber laser

    NASA Astrophysics Data System (ADS)

    Zhang, Haitao; Gao, Gan; Li, Qinghua; Gong, Mali

    2017-03-01

    Generation of high power double-scale pulses from a gain-guided double-clad fiber laser is experimentally demonstrated. By employing the Yb-doped 10/130 double-clad fiber as the gain medium, the laser realizes an output power of 5.1 W and pulse energy of 0.175 µJ at repetition rate of 29.14 MHz. To the best of our knowledge, this average output power is the highest among the reported double-scale pulse oscillators. The autocorrelation trace of pulses contains the short (98 fs) and long (29.5 ps) components, and the spectral bandwidth of the pulse is 27.3 nm. Such double-scale pulses are well suited for seeding the high power MOPA (master oscillator power amplifier) systems, nonlinear frequency conversion and optical coherence tomography.

  18. Evolution of the plasma composition of a high power impulse magnetron sputtering system studied with a time-of-flight spectrometer

    SciTech Connect

    Oks, Efim; Anders, Andre

    2008-12-31

    The plasma of a high power impulse magnetron sputtering (HiPIMS) system has been investigated using a time-of-flight (TOF) spectrometer. The target materials included high sputter yield materials (Cu, Ag), transition metals (Nb, Cr, Ti), and carbon (graphite); the sputtering gases were argon, krypton and nitrogen, and two different target thicknesses were selected to consider the role of the magnetic field strength. Measurements for selected combinations of those parameters give quantitative information on the transition from gas-dominated to metal-dominated (self-sputtering) plasma, on the fractions of ion charge states, and in the case of molecular gases, on the fraction of atomic and molecular ions.

  19. High-Power Multimode X-Band RF Pulse Compression System for Future Linear Colliders

    SciTech Connect

    Tantawi, S.G.; Nantista, C.D.; Dolgashev, V.A.; Pearson, C.; Nelson, J.; Jobe, K.; Chan, J.; Fant, K.; Frisch, J.; Atkinson, D.; /LLNL, Livermore

    2005-08-10

    We present a multimode X-band rf pulse compression system suitable for a TeV-scale electron-positron linear collider such as the Next Linear Collider (NLC). The NLC main linac operating frequency is 11.424 GHz. A single NLC rf unit is required to produce 400 ns pulses with 475 MW of peak power. Each rf unit should power approximately 5 m of accelerator structures. The rf unit design consists of two 75 MW klystrons and a dual-moded resonant-delay-line pulse compression system that produces a flat output pulse. The pulse compression system components are all overmoded, and most components are designed to operate with two modes. This approach allows high-power-handling capability while maintaining a compact, inexpensive system. We detail the design of this system and present experimental cold test results. We describe the design and performance of various components. The high-power testing of the system is verified using four 50 MW solenoid-focused klystrons run off a common 400 kV solid-state modulator. The system has produced 400 ns rf pulses of greater than 500 MW. We present the layout of our system, which includes a dual-moded transmission waveguide system and a dual-moded resonant line (SLED-II) pulse compression system. We also present data on the processing and operation of this system, which has set high-power records in coherent and phase controlled pulsed rf.

  20. Improving Reliability of High Power Quasi-CW Laser Diode Arrays Operating in Long Pulse Mode

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin; Meadows, Byron L.; Barnes, Bruce W.; Lockard, George E.; Singh, Upendra N.; Kavaya, Michael J.; Baker, Nathaniel R.

    2006-01-01

    Operating high power laser diode arrays in long pulse regime of about 1 msec, which is required for pumping 2-micron thulium and holmium-based lasers, greatly limits their useful lifetime. This paper describes performance of laser diode arrays operating in long pulse mode and presents experimental data of the active region temperature and pulse-to-pulse thermal cycling that are the primary cause of their premature failure and rapid degradation. This paper will then offer a viable approach for determining the optimum design and operational parameters leading to the maximum attainable lifetime.

  1. Generation of high-power ultrashort optical pulses by semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Dudelev, V. V.; Zazulin, S. V.; Kolykhalova, E. D.; Losev, S. N.; Deryagin, A. G.; Kuchinskii, V. I.; Efanov, M. V.; Sokolovskii, G. S.

    2016-12-01

    Fiber-coupled semiconductor lasers have been studied when pumped by high-power short electrical pulses of 5 ns width and leading front duration below 1 ns. In this pumping regime, it is possible to ensure significant sharpening of output pulses, the duration of which decreases below 80 ps for a single-mode laser and below 120 ps for a broad aperture multimode laser at an output peak optical power as high as 1.5 and 27 W, respectively.

  2. Fiber laser pumped high power mid-infrared laser with picosecond pulse bunch output.

    PubMed

    Wei, Kaihua; Chen, Tao; Jiang, Peipei; Yang, Dingzhong; Wu, Bo; Shen, Yonghang

    2013-10-21

    We report a novel quasi-synchronously pumped PPMgLN-based high power mid-infrared (MIR) laser with picosecond pulse bunch output. The pump laser is a linearly polarized MOPA structured all fiberized Yb fiber laser with picosecond pulse bunch output. The output from a mode-locked seed fiber laser was directed to pass through a FBG reflector via a circulator to narrow the pulse duration from 800 ps to less than 50 ps and the spectral FWHM from 9 nm to 0.15 nm. The narrowed pulses were further directed to pass through a novel pulse multiplier through which each pulse was made to become a pulse bunch composing of 13 sub-pulses with pulse to pulse time interval of 1.26 ns. The pulses were then amplified via two stage Yb fiber amplifiers to obtain a linearly polarized high average power output up to 85 W, which were then directed to pass through an isolator and to pump a PPMgLN-based optical parametric oscillator via quasi-synchronization pump scheme for ps pulse bunch MIR output. High MIR output with average power up to 4 W was obtained at 3.45 micron showing the feasibility of such pump scheme for ps pulse bunch MIR output.

  3. Fiber optic cables for transmission of high-power laser pulses

    NASA Astrophysics Data System (ADS)

    Thomes, W. Joe, Jr.; Ott, Melanie N.; Chuska, Richard F.; Switzer, Robert C.; Blair, Diana E.

    2011-09-01

    High power pulsed lasers are commonly deployed in harsh environments, like space flight and military missions, for a variety of systems such as LIDAR, optical communications over long distances, or optical firing of explosives. Fiber coupling of the laser pulse from the laser to where it is needed can often save size, reduce weight, and lead to a more robust and reliable system. Typical fiber optic termination procedures are not sufficient for injection of these high power laser pulses without catastrophic damage to the fiber endface. In the current study, we will review the causes of fiber damage during high power injection and discuss methods used to avoid these issues to permit fiber use with high reliability in these applications. A brief review of the design considerations for high peak power laser pulse injection will be presented to familiarize the audience with all the areas that need to be considered during the design phase. The majority of this paper focuses on the proper fiber polishing methods for high power use with an emphasis on laser polishing of the fibers. Results from recently build fibers will be shown to demonstrate the techniques.

  4. An ionization region model of the reactive Ar/O2 high power impulse magnetron sputtering discharge

    NASA Astrophysics Data System (ADS)

    Gudmundsson, Jon Tomas; Lundin, Daniel; Brenning, Nils; Raadu, Michel A.; Huo, Chunqing; Minea, Tiberiu

    2016-09-01

    A reactive ionization region model (R-IRM) is developed to describe the reactive Ar/O2 high power impulse magnetron sputtering (HiPIMS) discharge with titanium target. We compare the discharge properties when the discharge is operated in the two well established operating modes, the metal mode and the poisoned mode. Experimentally, it is found that in the metal mode the discharge current waveform displays a typical non-reactive evolution, while in the poisoned mode the discharge current waveform becomes distinctly triangular and the current increases significantly. Using the R-IRM we find that when the discharge is operated in the metal mode Ar+ and Ti+-ions contribute most significantly (roughly equal amounts) to the discharge current while in the poisoned mode the Ar+-ions contribute most significantly to the discharge current while the contribution of O+-ions and secondary electron emission is much smaller. Furthermore, we find that recycling of ionized atoms coming from the target are required for the current generation in both modes of operation. In the metal mode self-sputter recycling dominates and in the poisoned mode working gas recycling dominates, and it is concluded that the dominating type of recycling determines the discharge current waveform.

  5. An ionization region model of the reactive Ar/O2 high power impulse magnetron sputtering discharge

    NASA Astrophysics Data System (ADS)

    Gudmundsson, J. T.; Lundin, D.; Brenning, N.; Raadu, M. A.; Huo, Chunqing; Minea, T. M.

    2016-12-01

    A new reactive ionization region model (R-IRM) is developed to describe the reactive Ar/O2 high power impulse magnetron sputtering (HiPIMS) discharge with a titanium target. It is then applied to study the temporal behavior of the discharge plasma parameters such as electron density, the neutral and ion composition, the ionization fraction of the sputtered vapor, the oxygen dissociation fraction, and the composition of the discharge current. We study and compare the discharge properties when the discharge is operated in the two well established operating modes, the metal mode and the poisoned mode. Experimentally, it is found that in the metal mode the discharge current waveform displays a typical non-reactive evolution, while in the poisoned mode the discharge current waveform becomes distinctly triangular and the current increases significantly. Using the R-IRM we explore the current increase and find that when the discharge is operated in the metal mode Ar+ and Ti+ -ions contribute most significantly (roughly equal amounts) to the discharge current while in the poisoned mode the Ar+ -ions contribute most significantly to the discharge current and the contribution of O+ -ions, Ti+ -ions, and secondary electron emission is much smaller. Furthermore, we find that recycling of atoms coming from the target, that are subsequently ionized, is required for the current generation in both modes of operation. From the R-IRM results it is found that in the metal mode self-sputter recycling dominates and in the poisoned mode working gas recycling dominates. We also show that working gas recycling can lead to very high discharge currents but never to a runaway. It is concluded that the dominating type of recycling determines the discharge current waveform.

  6. High-Power Laser Pulse Recirculation for Inverse Compton Scattering-Produced Gamma-Rays

    SciTech Connect

    Jovanovic, I; Shverdin, M; Gibson, D; Brown, C

    2007-04-17

    Inverse Compton scattering of high-power laser pulses on relativistic electron bunches represents an attractive method for high-brightness, quasi-monoenergetic {gamma}-ray production. The efficiency of {gamma}-ray generation via inverse Compton scattering is severely constrained by the small Thomson scattering cross section. Furthermore, repetition rates of high-energy short-pulse lasers are poorly matched with those available from electron accelerators, resulting in low repetition rates for generated {gamma}-rays. Laser recirculation has been proposed as a method to address those limitations, but has been limited to only small pulse energies and peak powers. Here we propose and experimentally demonstrate an alternative method for laser pulse recirculation that is uniquely capable of recirculating short pulses with energies exceeding 1 J. Inverse Compton scattering of recirculated Joule-level laser pulses has a potential to produce unprecedented peak and average {gamma}-ray brightness in the next generation of sources.

  7. Propagation of long, high-power microwave pulses through the air

    SciTech Connect

    Khanaka, G.H.; Yee, J.H.

    1986-03-01

    The passage of long, high-power microwave pulses in the atmosphere was studied using a one-dimensional computer code. The objective of this study was to obtain a time history of the electron conductivity and peak density, as well as the peak plasma density. The results are summarized as follows: (1) the threshold level depends on pulse frequency and length; (2) electron avalanche occurs only when the pulse intensity exceeds the threshold level for air break-down, and this results in tail erosion; (3) for higher pulse intensities, it requires less time to initiate electron avalanche, which results in transmitting smaller portions of the pulse; (4) the general characteristics of the electron density, conductivity, and plasma frequency are quite similar for both cases; and (5) as the pulse amplitude rises, the electron conductivity and density and the plasma frequency also rise. 10 figs.

  8. Observation of a periodic runaway in the reactive Ar/O{sub 2} high power impulse magnetron sputtering discharge

    SciTech Connect

    Shayestehaminzadeh, Seyedmohammad E-mail: shayesteh@mch.rwth-aachen.de; Arnalds, Unnar B.; Magnusson, Rögnvaldur L.; Olafsson, Sveinn

    2015-11-15

    This paper reports the observation of a periodic runaway of plasma to a higher density for the reactive discharge of the target material (Ti) with moderate sputter yield. Variable emission of secondary electrons, for the alternating transition of the target from metal mode to oxide mode, is understood to be the main reason for the runaway occurring periodically. Increasing the pulsing frequency can bring the target back to a metal (or suboxide) mode, and eliminate the periodic transition of the target. Therefore, a pulsing frequency interval is defined for the reactive Ar/O{sub 2} discharge in order to sustain the plasma in a runaway-free mode without exceeding the maximum power that the magnetron can tolerate.

  9. High-Power Plasma Switch for 11.4 GHz Microwave Pulse Compressor

    SciTech Connect

    Jay L. Hirshfield

    2010-03-04

    Results obtained in several experiments on active RF pulse compression at X-band using a magnicon as the high-power RF source are presented. In these experiments, microwave energy was stored in high-Q TE01 and TE02 modes of two parallel-fed resonators, and then discharged using switches activated with rapidly fired plasma discharge tubes. Designs and high-power tests of several versions of the compressor are described. In these experiments, coherent pulse superposition was demonstrated at a 5–9 MW level of incident power. The compressed pulses observed had powers of 50–70 MW and durations of 40–70 ns. Peak power gains were measured to be in the range of 7:1–11:1 with efficiency in the range of 50–63%.

  10. Design and fabrication of hollow-core photonic crystal fibers for high-power ultrashort pulse transportation and pulse compression.

    PubMed

    Wang, Y Y; Peng, Xiang; Alharbi, M; Dutin, C Fourcade; Bradley, T D; Gérôme, F; Mielke, Michael; Booth, Timothy; Benabid, F

    2012-08-01

    We report on the recent design and fabrication of kagome-type hollow-core photonic crystal fibers for the purpose of high-power ultrashort pulse transportation. The fabricated seven-cell three-ring hypocycloid-shaped large core fiber exhibits an up-to-date lowest attenuation (among all kagome fibers) of 40 dB/km over a broadband transmission centered at 1500 nm. We show that the large core size, low attenuation, broadband transmission, single-mode guidance, and low dispersion make it an ideal host for high-power laser beam transportation. By filling the fiber with helium gas, a 74 μJ, 850 fs, and 40 kHz repetition rate ultrashort pulse at 1550 nm has been faithfully delivered at the fiber output with little propagation pulse distortion. Compression of a 105 μJ laser pulse from 850 fs down to 300 fs has been achieved by operating the fiber in ambient air.

  11. Method and apparatus for sputtering utilizing an apertured electrode and a pulsed substrate bias

    NASA Technical Reports Server (NTRS)

    Przybyszewski, J. S.; Shaltens, R. K. (Inventor)

    1973-01-01

    The method and equipment used for sputtering by use of an apertured electrode and a pulsed substrate bias are discussed. The technique combines the advantages of ion plating with the versatility of a radio frequency sputtered source. Electroplating is accomplished by passing a pulsed high voltage direct current to the article being plated during radio frequency sputtering.

  12. Experiment and theoretical study of the propagation of high power microwave pulse in air breakdown environment

    NASA Technical Reports Server (NTRS)

    Kuo, S. P.; Ren, A.; Zhang, Y. S.

    1991-01-01

    In the study of the propagation of high power microwave pulse, one of the main concerns is how to minimize the energy loss of the pulse before reaching the destination. In the very high power region, one has to prevent the cutoff reflection caused by the excessive ionization in the background air. A frequency auto-conversion process which can lead to reflectionless propagation of powerful EM pulses in self-generated plasmas is studied. The theory shows that under the proper conditions the carrier frequency, omega, of the pulse will indeed shift upward with the growth of plasma frequency, omega(sub pe). Thus, the plasma during breakdown will always remain transparent to the pulse (i.e., omega greater than omega(sub pe)). A chamber experiment to demonstrate the frequency auto-conversion during the pulse propagation through the self-generated plasma is then conducted in a chamber. The detected frequency shift is compared with the theoretical result calculated y using the measured electron density distribution along the propagation path of the pulse. Good agreement between the theory and the experiment results is obtained.

  13. Plasma Outages in Pulsed, High-Power RF Hydrogen Ion Sources

    NASA Astrophysics Data System (ADS)

    Stockli, Martin; Han, Baoxi; Murray, Syd; Pennisi, Terry; Piller, Chip; Santana, Manuel; Welton, Robert

    2011-04-01

    Pulsed, high-power RF ion sources are needed to produce copious amounts of negative H-ions for high-power accelerators with charge-changing injection schemes. When increasing the RF power, the plasma inductance changes the RF resonance, which drifts away from the low-power resonance. When the RF circuit is tuned to maximize the (pulsed) plasma power, the (off-resonance) power at the beginning of the pulse is reduced. If the induced electric fields fall below the breakdown strength of the hydrogen gas, the plasma fails to develop. This can be avoided with a compromise tune and/or by increasing the inductance of the resonant circuit. However, the breakdown strength of the hydrogen gas increases with time due to the gradual decrease of the electron-rich plasma impurities, which causes plasma outages after weeks of reliable operation. In this paper we discuss the success of different mitigations that were tested and implemented to overcome this fundamental problem of pulsed, high-power RF hydrogen ion sources.

  14. Influence of a falling edge on high power microwave pulse combination

    NASA Astrophysics Data System (ADS)

    Li, Jiawei; Huang, Wenhua; Zhu, Qi; Xiao, Renzhen; Shao, Hao

    2016-07-01

    This paper presents an explanation of the influence of a microwave falling edge on high-power microwave pulse combination. Through particle-in-cell simulations, we discover that the falling edge is the driving factor that limits the output power of the combined pulses. We demonstrate that the space charge field, which accumulates to become comparable to the E-field at the falling edge of the former pulse, will trap the electrons in the gas layer and decrease its energy to attain a high ionization rate. Hence, avalanche discharge, caused by trapped electrons, makes the plasma density to approach the critical density and cuts off the latter microwave pulse. An X-band combination experiment is conducted with different pulse intervals. This experiment confirms that the high density plasma induced by the falling edge can cut off the latter pulse, and that the time required for plasma recombination in the transmission channel is several microseconds. To ensure a high output power for combined pulses, the latter pulse should be moved ahead of the falling edge of the former one, and consequently, a beat wave with high peak power becomes the output by adding two pulses with normal amplitudes.

  15. Fast charge exchange ions in high power impulse magnetron sputtering of titanium as probes for the electrical potential

    NASA Astrophysics Data System (ADS)

    Breilmann, W.; Maszl, C.; von Keudell, A.

    2017-03-01

    High power impulse magnetron sputtering (HiPIMS) plasmas exhibit a high ionization fraction of the sputtered material and ions with high kinetic energies, which produce thin films with superior quality. These ion energy distribution functions (IEDF) contain energetic peaks, which are believed to be linked to a distinct electrical potential hump {{Δ }}{{{Φ }}}{{ionization}{{zone}}} inside rotating localized ionization zones, so called spokes, at target power densities above 1 kW cm‑2. Any direct measurement of this electrical potential structure is, however, very difficult due to the dynamic nature of the spokes and the very high local power density, which hampers the use of conventional emissive probes. Instead, we use a careful analysis of the IEDFs for singly and doubly charged titanium ions from a HiPIMS plasma at varying target power density. The energy peaks in the IEDFs measured at the substrate depend on the point of ionization and any charge exchange collisions on the path between ionization and impact at the substrate. Thereby, the IEDFs contain a convoluted information about the electrical potential structure inside the plasma. The analysis of these IEDFs reveal that higher ionization states originate at high target power densities from the central part of the plasma spoke, whereas singly charged ions originate from the perimeter of the plasma spoke. Consequently, we observe different absolute ion energies with the energy of Ti2+ being slightly higher than two times the energy of Ti+. Additional peaks are observed in the IEDFs of Ti+ originating from charge exchange reactions from Ti2+ and Ti3+ with titanium neutrals. Based on this analysis of the IEDFs, the structure of the electrical potential inside a spoke is inferred yielding {{Δ }}{{{Φ }}}{{ionization}{{zone}}} = 25 V above the plasma potential, irrespective of target power density.

  16. Self-Channeling of High-Power Long-Wave Infrared Pulses in Atomic Gases

    NASA Astrophysics Data System (ADS)

    Schuh, K.; Kolesik, M.; Wright, E. M.; Moloney, J. V.; Koch, S. W.

    2017-02-01

    We simulate and elucidate the self-channeling of high-power 10 μ m infrared pulses in atomic gases. The major new result is that the peak intensity can remain remarkably stable over many Rayleigh ranges. This arises from the balance between the self-focusing, diffraction, and defocusing caused by the excitation induced dephasing due to many-body Coulomb effects that enhance the low-intensity plasma densities. This new paradigm removes the Rayleigh range limit for sources in the 8 - 12 μ m atmospheric transmission window and enables transport of individual multi-TW pulses over multiple kilometer ranges.

  17. Self-Channeling of High-Power Long-Wave Infrared Pulses in Atomic Gases.

    PubMed

    Schuh, K; Kolesik, M; Wright, E M; Moloney, J V; Koch, S W

    2017-02-10

    We simulate and elucidate the self-channeling of high-power 10  μm infrared pulses in atomic gases. The major new result is that the peak intensity can remain remarkably stable over many Rayleigh ranges. This arises from the balance between the self-focusing, diffraction, and defocusing caused by the excitation induced dephasing due to many-body Coulomb effects that enhance the low-intensity plasma densities. This new paradigm removes the Rayleigh range limit for sources in the 8-12  μm atmospheric transmission window and enables transport of individual multi-TW pulses over multiple kilometer ranges.

  18. Single and repetitive short-pulse high-power microwave window breakdown

    SciTech Connect

    Chang, C.; Tang, C. X.; Shao, H.; Chen, C. H.; Huang, W. H.

    2010-05-15

    The mechanisms of high-power microwave breakdown for single and repetitive short pulses are analyzed. By calculation, multipactor saturation with electron density much higher than the critical plasma density is found not to result in microwave cutoff. It is local high pressure about Torr class that rapid plasma avalanche and final breakdown are realized in a 10-20 ns short pulse. It is found by calculation that the power deposited by saturated multipactor and the rf loss of protrusions are sufficient to induce vaporizing surface material and enhancing the ambient pressure in a single short pulse. For repetitive pulses, the accumulation of heat and plasma may respectively carbonize the surface material and lower the repetitive breakdown threshold.

  19. Emission properties of diode laser bars during pulsed high-power operation

    NASA Astrophysics Data System (ADS)

    Hempel, Martin; Tomm, Jens W.; Hennig, Petra; Elsaesser, Thomas

    2011-09-01

    High-power diode laser bars (cm-bars) are subjected to single pulse step tests carried out up to and beyond their ultimate limits of operation. Laser nearfields and thermal behaviour are monitored for pulse widths in the 10-100 µs range with streak- and thermo-cameras, respectively. Thresholds of catastrophic optical damage are determined, and their dependence on the length of the injected current pulses is explained qualitatively. This approach permits testing the hardness of facet coatings of cm-bars with or without consideration of accidental single pre-damaged emitter failure effects and thermal crosstalk between the emitters. This allows for the optimization of pulsed operation parameters, helps limiting sudden degradation and provides insight into the mechanisms governing the device emission behaviour at ultimate output powers.

  20. Permeabilization of yeast Saccharomyces cerevisiae cell walls using nanosecond high power electrical pulses

    NASA Astrophysics Data System (ADS)

    Stirke, A.; Zimkus, A.; Balevicius, S.; Stankevic, V.; Ramanaviciene, A.; Ramanavicius, A.; Zurauskiene, N.

    2014-12-01

    The electrical field-induced changes of the yeast Saccharomyces cerevisiae cells permeabilization to tetraphenylphosphonium (TPP+) ions were studied using square-shaped, nanosecond duration high power electrical pulses. It was obtained that pulses having durations ranging from 10 ns to 60 ns, and generating electric field strengths up to 190 kV/cm significantly (up to 65 times) increase the absorption rate of TPP+ ions without any detectible influence on the yeast cell viability. The modelling of the TPP+ absorption process using a second order rate equation demonstrates that depending on the duration of the pulses, yeast cell clusters of different sizes are homogeniously permeabilized. It was concluded, that nanosecond pulse-induced permeabilization can be applied to increase the operational speed of whole cell biosensors.

  1. Ferroelectric switch for a high-power Ka-band active pulse compressor

    SciTech Connect

    Hirshfield, Jay L.

    2013-12-18

    Results are presented for design of a high-power microwave switch for operation at 34.3 GHz, intended for use in an active RF pulse compressor. The active element in the switch is a ring of ferroelectric material, whose dielectric constant can be rapidly changed by application of a high-voltage pulse. As envisioned, two of these switches would be built into a pair of delay lines, as in SLED-II at SLAC, so as to allow 30-MW μs-length Ka-band pulses to be compressed in time by a factor-of-9 and multiplied in amplitude to generate 200 MW peak power pulses. Such high-power pulses could be used for testing and evaluation of high-gradient mm-wave accelerator structures, for example. Evaluation of the switch design was carried out with an X-band (11.43 GHz) prototype, built to incorporate all the features required for the Ka-band version.

  2. Enhanced multi-colour gating for the generation of high-power isolated attosecond pulses

    PubMed Central

    Haessler, S.; Balčiūnas, T.; Fan, G.; Chipperfield, L. E.; Baltuška, A.

    2015-01-01

    Isolated attosecond pulses (IAP) generated by high-order harmonic generation are valuable tools that enable dynamics to be studied on the attosecond time scale. The applicability of these IAP would be widened drastically by increasing their energy. Here we analyze the potential of using multi-colour driving pulses for temporally gating the attosecond pulse generation process. We devise how this approach can enable the generation of IAP with the available high-energy kHz-repetition-rate Ytterbium-based laser amplifiers (delivering 180-fs, 1030-nm pulses). We show theoretically that this requires a three-colour field composed of the fundamental and its second harmonic as well as a lower-frequency auxiliary component. We present pulse characterization measurements of such auxiliary pulses generated directly by white-light seeded OPA with the required significantly shorter pulse duration than that of the fundamental. This, combined with our recent experimental results on three-colour waveform synthesis, proves that the theoretically considered multi-colour drivers for IAP generation can be realized with existing high-power laser technology. The high-energy driver pulses, combined with the strongly enhanced single-atom-level conversion efficiency we observe in our calculations, thus make multi-colour drivers prime candidates for the development of unprecedented high-energy IAP sources in the near future. PMID:25997917

  3. Improving optical properties of silicon nitride films to be applied in the middle infrared optics by a combined high-power impulse/unbalanced magnetron sputtering deposition technique.

    PubMed

    Liao, Bo-Huei; Hsiao, Chien-Nan

    2014-02-01

    Silicon nitride films are prepared by a combined high-power impulse/unbalanced magnetron sputtering (HIPIMS/UBMS) deposition technique. Different unbalance coefficients and pulse on/off ratios are applied to improve the optical properties of the silicon nitride films. The refractive indices of the Si3N4 films vary from 2.17 to 2.02 in the wavelength ranges of 400-700 nm, and all the extinction coefficients are smaller than 1×10(-4). The Fourier transform infrared spectroscopy and x-ray diffractometry measurements reveal the amorphous structure of the Si3N4 films with extremely low hydrogen content and very low absorption between the near IR and middle IR ranges. Compared to other deposition techniques, Si3N4 films deposited by the combined HIPIMS/UBMS deposition technique possess the highest refractive index, the lowest extinction coefficient, and excellent structural properties. Finally a four-layer coating is deposited on both sides of a silicon substrate. The average transmittance from 3200 to 4800 nm is 99.0%, and the highest transmittance is 99.97% around 4200 nm.

  4. Pulse compression of a high-power thin disk laser using rod-type fiber amplifiers.

    PubMed

    Saraceno, C J; Heckl, O H; Baer, C R E; Südmeyer, T; Keller, U

    2011-01-17

    We report on two pulse compressors for a high-power thin disk laser oscillator using rod-type fiber amplifiers. Both systems are seeded by a standard SESAM modelocked thin disk laser that delivers 16 W of average power at a repetition rate of 10.6 MHz with a pulse energy of 1.5 μJ and a pulse duration of 1 ps. We discuss two results with different fiber parameters with different trade-offs in pulse duration, average power, damage and complexity. The first amplifier setup consists of a Yb-doped fiber amplifier with a 2200 μm2 core area and a length of 55 cm, resulting in a compressed average power of 55 W with 98-fs pulses at a repetition rate of 10.6 MHz. The second system uses a shorter 36-cm fiber with a larger core area of 4500 μm2. In a stretcher-free configuration we obtained 34 W of compressed average power and 65-fs pulses. In both cases peak powers of > 30 MW were demonstrated at several μJ pulse energies. The power scaling limitations due to damage and self-focusing are discussed.

  5. Transmission line pulse system for avalanche characterization of high power semiconductor devices

    NASA Astrophysics Data System (ADS)

    Riccio, Michele; Ascione, Giovanni; De Falco, Giuseppe; Maresca, Luca; De Laurentis, Martina; Irace, Andrea; Breglio, Giovanni

    2013-05-01

    Because of the increasing in power density of electronic devices for medium and high power application, reliabilty of these devices is of great interest. Understanding the avalanche behaviour of a power device has become very important in these last years because it gives an indication of the maximum energy ratings which can be seen as an index of the device ruggedness. A good description of this behaviour is given by the static IV blocking characteristc. In order to avoid self heating, very relevant in high power devices, very short pulses of current have to be used, whose value can change from few milliamps up to tens of amps. The most used method to generate short pulses is the TLP (Transmission Line Pulse) test, which is based on charging the equivalent capacitance of a transmission line to high value of voltage and subsequently discharging it onto a load. This circuit let to obtain very short square pulses but it is mostly used for evaluate the ESD capability of semiconductor and, in this environment, it generates pulses of low amplitude which are not high enough to characterize the avalanche behaviour of high power devices . Advanced TLP circuit able to generate high current are usually very expensive and often suffer of distorption of the output pulse. In this article is proposed a simple, low cost circuit, based on a boosted-TLP configuration, which is capable to produce very square pulses of about one hundreds of nanosecond with amplitude up to some tens of amps. A prototype is implemented which can produce pulses up to 20A of amplitude with 200 ns of duration which can characterize power devices up to 1600V of breakdown voltage. Usage of microcontroller based logic make the circuit very flexible. Results of SPICE simulation are provided, together with experimental results. To prove the effectiveness of the circuit, the I-V blocking characteristics of two commercial devices, namely a 600V PowerMOS and a 1200V Trench-IGBT, are measured at different

  6. High Power, Repetitive, Stacked Blumlein Pulse Generators Commuted by a Single Switching Element

    NASA Astrophysics Data System (ADS)

    Bhawalkar, Jayant Dilip

    In this work, the stacked Blumlein pulsers developed at the University of Texas at Dallas were characterized and shown to be versatile sources of pulse power for a variety of applications. These devices consisted of several triaxial Blumleins stacked in series at one end. The lines were charged in parallel and synchronously commuted repetitively with a single switching element at the other end. In this way, relatively low charging voltages were multiplied to give a high discharge voltage across an arbitrary load without the need for complex Marx bank circuitry. Several pulser parameters such as the number of stacked Blumlein lines, line configuration, type of switching element, and the length of the lines, were varied and the waveform characteristics were observed and analyzed. It was shown that these devices are capable of generating fast rising waveforms with a wide range of peak voltage and current values. The generation of high power waveforms with pulse durations in the range of 80-600 ns was demonstrated without degradation of the voltage gains. The results of this work indicated that unlike generators based on stacked transmission lines, the effects of parasitic modes were not appreciable for the stacked Blumlein pulsers. Opportunities for tactically packaging these pulsers were also investigated and a significant reduction in their size and weight was demonstrated. For this, dielectric lifetime and Blumlein spacing studies were performed on small scale prototypes. In addition to production of intense X-ray pulses, the possible applications for these novel pulsers include driving magnetrons for high power microwave generation, pumping laser media, or powering e-beam diodes. They could also serve as compact, tabletop sources of high power pulses for various research experiments.

  7. Use of pulsed high power ion beams to enhance tribological properties of stainless steel, Ti, and Al

    SciTech Connect

    Senft, D.C.; Renk, T.J.; Dugger, M.T.; Grabowski, K.S.; Thompson, M.O.

    1998-04-01

    Enhanced tribological properties have been observed after treatment with pulsed high power ion beams, which results in rapid melting and resolidification of the surface. The authors have treated and tested 440C martensitic stainless steel (Fe-17 Cr-1 C). Ti and Al samples were sputter coated and ion beam treated to produce surface alloying. The samples were treated at the RHEPP-I facility at Sandia National Laboratories (0.5 MV, 0.5--1 {micro}s at sample location, <10 J/cm{sup 2}, 1--5 {micro}m ion range). They have observed a reduction in size of second phase particles and other microstructural changes in 440C steel. The hardness of treated 440C increases with ion beam fluence and a maximum hardness increase of a factor of 5 is obtained. Low wear rates are observed in wear tested of treated 440C steel. Surface alloyed Ti-Pt layers show improvements in hardness up to a factor of 3 over untreated Ti, and surface alloys of Al-Si result in a hardness increase of a factor of two over untreated Al. Both surface alloys show increased durability in wear testing. Rutherford Backscattering (RBS) measurements show overlayer mixing to the depth of the melted layer. X-ray Diffraction (XRD) and TEM confirm the existence of metastable states within the treated layer. Treated layer depths have been measured from 1--10 {micro}m.

  8. Radar Waveform Pulse Analysis Measurement System for High-Power GaN Amplifiers

    NASA Technical Reports Server (NTRS)

    Thrivikraman, Tushar; Perkovic-Martin, Dragana; Jenabi, Masud; Hoffman, James

    2012-01-01

    This work presents a measurement system to characterize the pulsed response of high-power GaN amplifiers for use in space-based SAR platforms that require very strict amplitude and phase stability. The measurement system is able to record and analyze data on three different time scales: fast, slow, and long, which allows for greater detail of the mechanisms that impact amplitude and phase stability. The system is fully automated through MATLAB, which offers both instrument control capability and in-situ data processing. To validate this system, a high-power GaN HEMT amplifier operated in saturation was characterized. The fast time results show that variations to the amplitude and phase are correlated to DC supply transients, while long time characteristics are correlated to temperature changes.

  9. High-Power Tunable Laser Pulse Driven Terahertz Generation in Corrugated Plasma Waveguides

    NASA Astrophysics Data System (ADS)

    Miao, Chenlong; Palastro, John; Antonsen, Thomas

    2016-10-01

    Excitation of terahertz radiation by the interaction of an ultra-short laser pulse and the fields of a miniature, corrugated plasma waveguide is considered. Plasma structures of this type have been realized experimentally and they can support electromagnetic (EM) channel modes with properties that allow for radiation generation. In particular, the mode have subluminal field components, thus allowing phase matching between the generated THz modes and the ponderomotive potential of the laser pulse. Theoretical analysis and full format PIC simulations are conducted. We find THz generated by this slow wave phase matching mechanism is characterized by lateral emission and a coherent, narrow band, tunable spectrum with relatively high power and conversion efficiency. We investigated two different types of channels, and a range of realistic laser pulses and plasma profile parameters are considered with the goal of increasing the conversion of optical energy to THz radiation. We find high laser intensities strongly modify the THz spectrum by exciting higher order channel modes. Enhancement of a specific channel mode can be realized by using an optimum pulse duration and plasma density. As an example, a fixed drive pulse (0.55 J) with spot size of 15 µm and pulse duration of 15 fs excites 37.8 mJ of THz radiation in a 1.5 cm corrugated plasma waveguide with on axis average density of 1.4×1018cm-3, conversion efficiency exceeding 8% is achieved.

  10. High-power pulsed ytterbium fibre laser with 10{-}\\unicode{956} {\\text{J}} pulse energy

    NASA Astrophysics Data System (ADS)

    Trikshev, A. I.; Kamynin, V. A.; Tsvetkov, V. B.; Egorova, O. N.

    2016-12-01

    An all-fibre pulsed fibre laser system emitting at a wavelength of 1093 {\\text{nm}} with an average output power up to 10 {\\text{W}} is presented. The system is assembled according to the master oscillator/fibre amplifier scheme. Pulses were generated with passive mode locking due to nonlinear polarisation rotation in a standard single-mode fibre. The main fibre amplifier was pumped by fibre-coupled semiconductor laser diodes at a wavelength of 976 {\\text{nm}} with a maximum total power up to 50 {\\text{W}}. The measured pump duration did not exceed 60 {\\text{ps}} at a pulse repetition rate of about 1 {\\text{MHz}}. The pulse energy was 10 \\unicode{956} {\\text{J}}.

  11. Upgrade of the SLAC SLED II Pulse Compression System Based on Recent High Power Tests

    SciTech Connect

    Vlieks, A.E.; Fowkes, W.R.; Loewen, R.J.; Tantawi, S.G.; /SLAC

    2011-09-06

    In the Next Linear Collider (NLC) it is expected that the high power rf components be able to handle peak power levels in excess of 400 MW. We present recent results of high power tests designed to investigate the RF breakdown limits of the X-band pulse compression system used at SLAC. (SLED-II). Results of these tests show that both the TE{sub 01}-TE{sub 10} mode converter and the 4-port hybrid have a maximum useful power limit of 220-250 MW. Based on these tests, modifications of these components have been undertaken to improve their peak field handling capability. Results of these modifications will be presented. As part of an international effort to develop a new 0.5-1.5 TeV electron-positron linear collider for the 21st century, SLAC has been working towards a design, referred to as 'The Next Linear Collider' (NLC), which will operate at 11.424 GHz and utilize 50-75 MW klystrons as rf power sources. One of the major challenges in this design, or any other design, is how to generate and efficiently transport extremely high rf power from a source to an accelerator structure. SLAC has been investigating various methods of 'pulse compressing' a relatively wide rf pulse ({ge} 1 {mu}s) from a klystron into a narrower, but more intense, pulse. Currently a SLED-II pulse compression scheme is being used at SLAC in the NLC Test Accelerator (NLCTA) and in the Accelerator Structures Test Area (ASTA) to provide high rf power for accelerator and component testing. In ASTA, a 1.05 {mu}s pulse from a 50 MW klystron was successfully pulse compressed to 205 MW with a pulse width of 150 ns. Since operation in NLC will require generating and transporting rf power in excess of 400 MW it was decided to test the breakdown limits of the SLED-II rf components in ASTA with rf power up to the maximum available of 400 MW. This required the combining of power from two 50 MW klystrons and feeding the summed power into the SLED-II pulse compressor. Results from this experiment demonstrated

  12. DIAL monitoring of atmospheric climate-determining gases employing high-power pulsed laser diodes

    NASA Astrophysics Data System (ADS)

    Penchev, Stoyan P.; Naboko, Sergei V.; Naboko, Vassily N.; Pencheva, Vasilka H.; Donchev, T.; Pavlov, Lyubomir Y.; Simeonov, P.

    2003-11-01

    High-power pulsed laser diodes are employed for determining atmospheric humidity and methane. The proposed DIAL method optimizes the spectral properties of laser radiation within the molecular absorption bands of 0.86 - 0.9 μm of these major greenhouse gases. The explicit absorption spectrum is explored by computational convolution method based on reference data on spectral linestrengths modulated by the characteristic broad laser line of the selected laser diodes. The lidar scheme is ultimately compact, of low-energy consumption and suggests a large potential for ecological monitoring.

  13. Characterization of mechanical shock waves in aluminum 6061-T6 using a high power laser pulse

    NASA Astrophysics Data System (ADS)

    Gonzalez Romero, J. R.; García-Torales, G.; Gómez Rosas, G.; Ocaña, J. L.; Flores, Jorge L.

    2016-09-01

    Strengthening techniques allows enhance metal physical properties. Laser shock peening (LSP) technique consist in a surface treatment which a high power laser pulse induces a compressive residual stress field through mechanical shock waves, increasing hardness, corrosion resistance, fatigue resistance. In comparison with the shot peening technique, LSP is a method that allows precision controlling the laser incidence on the surface under treatment increasing the surface quality in the surface under treatment. In this work, mechanical shock waves are induced in aluminum and measure using two different experimental approaches. First, using a PVDZ sensors and secondly, strain gauges are used. Experimental results are presented.

  14. A long pulse high-power diode based on a microelectronic emitter

    SciTech Connect

    Marder, B.; Clark, C.; Walko, R.; Fleming, J.

    1995-11-01

    Microelectronic cathode emitter technology being developed at Sandia for supplying continuous low current for flat panel displays appears to be a promising technology for providing high currents when operated in a pulsed, higher voltage mode. If currents in excess of one amp per square centimeter could be produced for tens of microseconds at several kilohertz repetition rate, important applications in such as large volume food or waste sterilization in situ detection, and high power microwave production could be achieved. A testbed was built to perform the experiments. The desired current densities have been demonstrated using small emitter arrays.

  15. Study of the crystalline and optical properties of lithium tantalate thin films deposited by high power RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Pan, Dong; Wang, Jun; Sun, Binwei; Gou, Jun

    2017-02-01

    Lithium tantalate (LiTaO3) thin films were deposited by high power (250 W) RF magnetron sputtering on Pt/Ti/SiO2/Si(100) substrates and were annealed from 600 °C–700 °C in an O2 or N2 environment. The crystallinity of those films were examined by x-ray diffraction and Raman spectra to study the effects of annealing temperature and annealing gas on the crystal properties of LiTaO3 thin films. LiTaO3 thin films annealing at 650 °C in O2 have a better crystalline quality in a (012) preferential orientation. However, LiTaO3 thin films annealed at 700 °C in O2 contain impurities with titanium oxide (Ta2O5). This is attributable to the fact that the crystal structure is unstable above the Curie temperature and the tantalum reacts with oxygen in the annealing process. At the same time, the result of the Raman spectra suggests that LiTaO3 thin films annealed at 600 °C and 650 °C are closer to near-stoichiometric LiTaO3 and have less Li diffusivity and Li-deficient phases. Finally, optical constants of LiTaO3 films are also primarily probed by spectroscopic ellipsometry. For LiTaO3 thin films annealed at 650 °C in O2, the refractive index is 2.33, the extinction coefficient is 0.002 34 and the direct optical band gap energy is estimated to be minimal at 3.66 eV.

  16. Reactive pulsed magnetron-sputtered tantalum oxide thin films

    NASA Astrophysics Data System (ADS)

    Nielsen, Matthew Christian

    Current high speed, advanced packaging applications require the use of integrated capacitors. Tantalum oxide is one material currently being considered for use in the capacitors; however, the deposition technique used to make the thin film dielectric can alter its performance. Pulsed magnetron reactive sputtering was investigated in this thesis as it offers a robust, clean, and low temperature deposition alternative. This is a new deposition technique created to control the negative effects of target poisoning; however, to understand the relationships between the deposition variables and the resultant film properties a thorough investigation is needed. The instantaneous voltage at the target was captured using a high speed digital oscilloscope. Three target oxidation states were imaged and identified to be that of the metallic and oxidized states with an abrupt transition region separating the two. Using high resolution X-ray photoelectron spectroscopy the bonding present in the deposited films was correlated to the oxidation state of the target. While operating the target in the metallic mode, a mix of oxidized, sub-oxide and metallic states were discovered. Alternatively, the bonding present in the films deposited when the target was in the oxidized state were that of fully oxidized tantalum pentoxide. The films deposited above the critical partial pressure demonstrated excellent leakage current densities. The exact magnitude of the leakage current density inversely scaled to the relative amount of oxygen included into the sputtering atmosphere. Detailed plot analysis showed that there were two different conduction mechanisms controlling the current flow in the capacitors. High frequency test vehicles were measured up to 10 GHz in order to determine the frequency response of the dielectric material. A circuit equivalent model describing the testing system and samples was created and utilized to fit the collected data. Overall, the technique of pulsed magnetron

  17. A source of high-power pulses of elliptically polarized ultrawideband radiation

    SciTech Connect

    Andreev, Yu. A. Efremov, A. M.; Koshelev, V. I.; Kovalchuk, B. M.; Petkun, A. A.; Sukhushin, K. N.; Zorkaltseva, M. Yu.

    2014-10-01

    Here, we describe a source of high-power ultrawideband radiation with elliptical polarization. The source consisting of a monopolar pulse generator, a bipolar pulse former, and a helical antenna placed into a radioparent container may be used in tests for electromagnetic compatibility. In the source, the helical antenna with the number of turns N = 4 is excited with a high-voltage bipolar pulse. Preliminary, we examined helical antennas at a low-voltage source aiming to select an optimal N and to estimate a radiation center position and boundary of a far-field zone. Finally, characteristics of the source in the operating mode at a pulse repetition rate of 100 Hz are presented in the paper as well. Energy efficiency of the antenna is 0.75 at the axial ratio equal to 1.3. The effective potential of radiation of the source at the voltage amplitudes of the bipolar pulse generator equal to -175/+200 kV reaches 280 kV.

  18. High-power rf pulse compression with SLED-II at SLAC

    SciTech Connect

    Nantista, C.; Kroll, N.M.; Farkas, Z.D.; Lavine, T.L.; Menegat, A.; Ruth, R.D.; Tantawi, S.G.; Vlieks, A.E.; Wilson, P.B.

    1993-04-01

    Increasing the peak rf power available from X-band microwave tubes by means of rf pulse compression is envisioned as a way of achieving the few-hundred-megawatt power levels needed to drive a next-generation linear collider with 50--100 MW klystrons. SLED-II is a method of pulse compression similar in principal to the SLED method currently in use on the SLC and the LEP injector linac. It utilizes low-los resonant delay lines in place of the storage cavities of the latter. This produces the added benefit of a flat-topped output pulse. At SLAC, we have designed and constructed a prototype SLED-II pulse-compression system which operates in the circular TE{sub 01} mode. It includes a circular-guide 3-dB coupler and other novel components. Low-power and initial high-power tests have been made, yielding a peak power multiplication of 4.8 at an efficiency of 40%. The system will be used in providing power for structure tests in the ASTA (Accelerator Structures Test Area) bunker. An upgraded second prototype will have improved efficiency and will serve as a model for the pulse compression system of the NLCTA (Next Linear Collider Test Accelerator).

  19. High power high repetition rate VCSEL array side-pumped pulsed blue laser

    NASA Astrophysics Data System (ADS)

    van Leeuwen, Robert; Zhao, Pu; Chen, Tong; Xu, Bing; Watkins, Laurence; Seurin, Jean-Francois; Xu, Guoyang; Miglo, Alexander; Wang, Qing; Ghosh, Chuni

    2013-03-01

    High power, kW-class, 808 nm pump modules based on the vertical-cavity surface-emitting laser (VCSEL) technology were developed for side-pumping of solid-state lasers. Two 1.2 kW VCSEL pump modules were implemented in a dual side-pumped Q-switched Nd:YAG laser operating at 946 nm. The laser output was frequency doubled in a BBO crystal to produce pulsed blue light. With 125 μs pump pulses at a 300 Hz repetition rate 6.1 W QCW 946 nm laser power was produced. The laser power was limited by thermal lensing in the Nd:YAG rod.

  20. Pulsed operation of high-power light emitting diodes for imaging flow velocimetry

    NASA Astrophysics Data System (ADS)

    Willert, C.; Stasicki, B.; Klinner, J.; Moessner, S.

    2010-07-01

    High-powered light emitting diodes (LED) are investigated for possible uses as light sources in flow diagnostics, in particular, as an alternative to laser-based illumination in particle imaging flow velocimetry in side-scatter imaging arrangements. Recent developments in solid state illumination resulted in mass-produced LEDs that provide average radiant power in excess of 10 W. By operating these LEDs with short duration, pulsed currents that are considerably beyond their continuous current damage threshold, light pulses can be generated that are sufficient to illuminate and image micron-sized particles in flow velocimetry. Time-resolved PIV measurements in water at a framing rate of 2kHz are presented. The feasibility of LED-based PIV measurements in air is also demonstrated.

  1. High power, short pulses ultraviolet laser for the development of a new x-ray laser

    SciTech Connect

    Meixler, L.; Nam, C.H.; Robinson, J.; Tighe, W.; Krushelnick, K.; Suckewer, S.; Goldhar, J.; Seely, J.; Feldman, U.

    1989-04-01

    A high power, short pulse ultraviolet laser system (Powerful Picosecond-Laser) has been developed at the Princeton Plasma Physics Laboratory (PPPL) as part of experiments designed to generate shorter wavelength x-ray lasers. With the addition of pulse compression and a final KrF amplifier the laser output is expected to have reached 1/3-1/2 TW (10/sup 12/ watts) levels. The laser system, particularly the final amplifier, is described along with some initial soft x-ray spectra from laser-target experiments. The front end of the PP-Laser provides an output of 20--30 GW (10/sup 9/ watts) and can be focussed to intensities of /approximately/10/sup 16/ W/cm/sup 2/. Experiments using this output to examine the effects of a prepulse on laser-target interaction are described. 19 refs., 14 figs.

  2. Defects Induced in Fused Silica by High Power UV Laser Pulses at 355 nm

    SciTech Connect

    Stevens-Kalceff, M A; Stesmans, A; Wong, J

    2001-03-23

    Point defects induced in high quality optical-grade based silica by high power (>30 J/cm{sup 2}) 355 nm laser pulses have been investigated to elucidate the nature of laser damage in transparent optics designed for use at the National Ignition Facility (NIF). Six defects have been identified: the NBOHC (non-bridging oxygen hole center), a STE (self-trapped exciton), an ODC (oxygen-deficient center), interstitial oxygen, the E'{sub {gamma}}, and E'{sub 74}. The former four defects were identified and spatially resolved in the damage craters using cathodoluminescence (CL) microanalysis (spectroscopy and microscopy). The latter two defects were identified using ESR spectroscopy at cryogenic temperatures. These defects are unlikely to be a prime factor in damage growth by subsequent laser pulses. Their concentration is too low to effect a high enough temperature rise by a volume absorption mechanism.

  3. Formation of short high-power laser radiation pulses in excimer mediums

    NASA Astrophysics Data System (ADS)

    Losev, V. F., Sr.; Ivanov, N. G.; Panchenko, Yu. N.

    2007-06-01

    Presently an excimer mediums continue are examined as one of variants for formation of powerful and over powerful pulses of laser radiation with duration from units of nanosecond up to tens femtosecond. The researches on such powerful installations as "NIKE" (USA) and << SUPER ASHURA >>, Japan) proceed in this direction. The main advantage of excimer mediums is the opportunity to work in a frequency mode, absence of restriction on the size of active area, high uniformity of a gas working medium, high efficiency (up to 10 %) and wide spectral range of laser radiation (KrF, XeCl ~ 2nm, XeF (C-A), Xe IICl ~ 50-100 nanometers). Research in area of high quality laser beams formation in excimer mediums and its amplification in high power amplifiers are carried out the long time in Institute of High Current Electronics SB RAS, Tomsk, Russia. The wide aperture XeCl laser system of MELS-4k is used for these investigations. Last time we take part in program on development of high power excimer laser system with a petawatt level of power. This system supposes the formation and amplification high quality laser beams with different pulse duration from units of nanosecond up to tens femtosecond. We research the possibility of laser beams formation in excimer mediums with ps-ns pulse duration having the low noise and divergence near to diffraction limit. In other hand, we are developing the wide aperture XeF(C-A) amplifier with optical pump on base electron accelerator. According to our estimations of the XeF(C-A) amplifier based on the converter of e-beam energy to the Xe II* fluorescence at 172 nm will allow to obtain up to 100 TW peak power in a 30 fs pulse.

  4. Generation of Alfven waves by high power pulse at the electron plasma frequency

    NASA Astrophysics Data System (ADS)

    van Compernolle, Bart Gilbert

    The physics of the interaction between plasmas and high power waves with frequencies in the electron plasma frequency range is of importance in many areas of space and plasma physics. A great deal of laboratory research has been done on the interaction of microwaves in a density gradient when o = ope in unmagnetized plasmas. [SWK74, WS78, KSW74]. Extensive studies of HF-ionospheric modifications have been performed [Fej79] as evidenced by experiments at Arecibo [HMD92, BHK86, CDF92, FGI85], at the HAARP facility [RKK98] in Alaska, at the EISCAT observatory in Norway [IHR99], and at SURA in Russia [FKS99]. This dissertation focusses on the interaction with a fully magnetized plasma, capable of supporting Alfven waves. The experiment is performed in the upgraded LArge Plasma Device (LAPD) at UCLA [GPL91] (Helium, n = 1012 cm-3, B = 1 kG - 2.5 kG). A number of experiments have been done at LAPD using antennas, skin depth scale currents and laser produced plasmas to generate Alfven waves [LGM99, GVL97a, GVL97b, VGV01]. In this work a high power pulse 6th, frequency in the electron plasma frequency range is launched into the radial density gradient, perpendicular to the background magnetic field. The microwave pulses last on the order of one ion gyro period and has a maximum power of |E|2/ nT ≃ .5 in the afterglow. The absorption of these waves leads to a pulse of field aligned suprathermal electrons. This electron current pulse then launches with Alfven wave with o ≤ o ci. The experiment was performed bath in ordinary node (O-mode) and extraordinary (X-mode), for different background magnetic fields B0, different temperatures (afterglow vs discharge) and different power levels of the incoming microwaves. It was found that the Alfven wave generation can be explained by Cherenkov radiation of Alfven waves by the suprathermal electron pulse. Theoretical solutions for the perturbed magnetic field due to a pulse of field aligned electrons were obtained, and shown to be

  5. High-power picosecond pulse delivery through hollow core photonic band gap fibers

    NASA Astrophysics Data System (ADS)

    Michieletto, Mattia; Johansen, Mette M.; Lyngsø, Jens K.; Lægsgaard, Jesper; Bang, Ole; Alkeskjold, Thomas T.

    2016-03-01

    We demonstrated robust and bend insensitive fiber delivery of high power laser with diffraction limited beam quality for two different kinds of hollow core band gap fibers. The light source for this experiment consists of ytterbium-doped double clad fiber aeroGAIN-ROD-PM85 in a high power amplifier setup. It provided 22ps pulses with a maximum average power of 95W, 40MHz repetition rate at 1032nm (~2.4μJ pulse energy), with M2 <1.3. We determined the facet damage threshold for a 7-cells hollow core photonic bandgap fiber and showed up to 59W average power output for a 5 meters fiber. The damage threshold for a 19-cell hollow core photonic bandgap fiber exceeded the maximum power provided by the light source and up to 76W average output power was demonstrated for a 1m fiber. In both cases, no special attention was needed to mitigate bend sensitivity. The fibers were coiled on 8 centimeters radius spools and even lower bending radii were present. In addition, stimulated rotational Raman scattering arising from nitrogen molecules was measured through a 42m long 19 cell hollow core fiber.

  6. Short-pulse Calorimetric Load for High Power Millimeter-wave Beams

    NASA Astrophysics Data System (ADS)

    Gandini, F.; Bruschi, A.; Cirant, S.; Gittini, G.; Granucci, G.; Muzzini, V.; Sozzi, C.; Spinicchia, N.

    2007-02-01

    A spherical compact matched load, for high vacuum operation suited for short pulses (2 MW, 0.1 s) precise measurement has been designed to test high power gyrotrons Bruschi, Gandini, Muzzini, Spinicchia, Cirant, Gittini, Granucci, Mellera, Nardone, Simonetto, and Sozzi (Fusion Eng. Des. 56 57:649 654, 2001); Bruschi, Cirant, Gandini, Granucci, Mellera, Muzzini, Nardone, Simonetto, Sozzi, and Spinicchia (Nucl. Fusion 43:1513 1519, 2003); Bruschi, Cirant, Gandini, Gittini, Granucci, Mellera, Muzzini, Nardone, Simonetto, Sozzi, Spinicchia, Angella, and Signorelli (Development of CW and short-pulse calorimetric loads for high power millimeter-wave Beams, 23rd Symposium on Fusion Technology, September 20 24, 2004, Venice, Italy). In order to enhance the power handling capability of the load and to reduce the operation problems that may arise from an excessive reflection from the load, a ray tracing code has been written to model the power distribution on the inner surface and the pattern of the reflected radiation. The outcome of this code has been used to select a more convenient profile for the spreading mirror of the load and to optimize a pre-load specially conceived to minimize the power reflected fraction.

  7. Compact, high-pulse-energy, high-power, picosecond master oscillator power amplifier.

    PubMed

    Chan, Ho-Yin; Alam, Shaif-Ul; Xu, Lin; Bateman, James; Richardson, David J; Shepherd, David P

    2014-09-08

    We report a compact, stable, gain-switched-diode-seeded master oscillator power amplifier (MOPA), employing direct amplification via conventional Yb(3+)-doped fibers, to generate picosecond pulses with energy of 17.7 μJ and 97-W average output power (excluding amplified spontaneous emission) at 5.47-MHz repetition frequency in a diffraction-limited and single-polarization beam. A maximum peak power of 197 kW is demonstrated. Such a high-energy, high-power, MHz, picosecond MOPA is of great interest for high-throughput material processing. With 13.8-μJ pulse energy confined in the 0.87-nm 3-dB spectral bandwidth, this MOPA is also a promising source for nonlinear frequency conversion to generate high-energy pulses in other spectral regions. We have explored the pulse energy scaling until the stimulated Raman Scattering (SRS) becomes significant (i.e. spectral peak intensity exceeds 1% of that of the signal).

  8. Plasma-based amplification and manipulation of high-power laser pulses

    NASA Astrophysics Data System (ADS)

    Lehmann, Goetz

    2016-10-01

    In the last decade the increasing availability of Tera- and Petawatt class lasers with ps to fs pulse duration has intensified the interest in the relativistic interaction between laser radiation and matter. Today laser intensities up to 1022 W/cm2 can be achieved. Most high intensity lasers today rely on amplification schemes that can only hardly be scaled to higher power levels due to material damage thresholds. An alternative approach that allows circumventing these issues is the use of plasma as an amplification medium. Langmuir or ion waves may be used as optical components, scattering the energy from a long pump pulse into a short seed pulse. Damage thresholds of solid-state materials are not only limiting the generation of high power laser light, but also its subsequent manipulation. Again, plasma can provide an alternative approach to light manipulation. We recently proposed the concept of transient plasma photonic crystals, which aims at transferring and extending the concept of photonic crystals to the realm of plasma physics in the range of optical frequencies. In my presentation I will discuss Brillouin type plasma-based laser amplifiers and show that the ion plasma waves, driven by the two laser pulses, eventually form photonic crystals. The properties and possible future applications of these plasma photonic crystals as efficient Bragg type mirrors or polarizers will be discussed.

  9. Thin Film Delamination Using a High Power Pulsed Laser Materials Interaction

    NASA Astrophysics Data System (ADS)

    Sherman, Bradley

    Thin films attached to substrates are only effective while the film is adhered to the substrate. When the film begins to spall the whole system can fail, thus knowing the working strength of the film substrate system is important when designing structures. Surface acoustic waves (SAWs) are suitable for characterization of thin film mechanical properties due to the confinement of their energy within a shallow depth from a material surface. In this project, we study the feasibility of inducing dynamic interfacial failure in thin films using surface waves generated by a high power pulsed laser. Surface acoustic waves are modeled using a finite element numerical code, where the ablative interaction between the pulsed laser and the incident film is modeled using equivalent surface mechanical stresses. The numerical results are validated using experimental results from a laser ultrasonic setup. Once validated the normal film-substrate interfacial stress can be extracted from the numerical code and tends to be in the mega-Pascal range. This study uses pulsed laser generation to produce SAW in various metallic thin film/substrate systems. Each system varies in its response based on its dispersive relationship and as such requires individualized numerical modeling to match the experimental data. In addition to pulsed SAW excitation using an ablative source, a constrained thermo-mechanical load produced by the ablation of a metal film under a polymer layer is explored to generate larger dynamic mechanical stresses. These stresses are sufficient to delaminate the thin film in a manner similar to a peel test. However, since the loading is produced by a pulsed laser source, it occurs at a much faster rate, limiting the influence of slower damage modes that are present in quasi-static loading. This approach is explored to predict the interfacial fracture toughness of weak thin film interfaces.

  10. Emission properties of diode laser bars during pulsed high-power operation

    NASA Astrophysics Data System (ADS)

    Olecki, Marcin; Tomm, Jens W.; Hempel, Martin; Hennig, Petra; Elsaesser, Thomas

    2012-03-01

    High power diode laser bars are subjected to single pulse step tests carried out up to and beyond their ultimate limits of operation. Laser nearfields and thermal behavior are monitored for pulse widths in the 10 μs-2 ms-range with streak- and thermo-cameras, respectively. The final phase of the tests allows the in situ observation of the catastrophic optical damage (COD) effect. We find perfect agreement between the location of COD signatures observed by transient emission and thermo-camera measurements on the one side, and optical inspection of the degraded bars on the other side. COD thresholds are determined and the observed dependence on the pulse length is qualitatively explained. This approach allows for testing hardness and homogeneity of facet coatings on a bar level with or without consideration of accidental early single-emitter failure effects and thermal crosstalk between the emitters. It helps embanking sudden degradation and provides insight into the mechanisms governing the device emission behavior at ultimate output powers.

  11. High-Power X-Band Semiconductor RF Switch for Pulse Compression Systems of Future Colliders

    NASA Astrophysics Data System (ADS)

    Tantawi, Sami G.; Tamura, Fumihiko

    2000-04-01

    We describe the potential of semiconductor X-band RF switch arrays as a means of developing high power RF pulse compression systems for future linear colliders. The switch systems described here have two designs. Both designs consist of two 3dB hybrids and active modules. In the first design the module is composed of a cascaded active phase shifter. In the second design the module uses arrays of SPST (Single Pole Single Throw) switches. Each cascaded element of the phase shifter and the SPST switch has similar design. The active element consists of symmetrical three-port tee-junctions and an active waveguide window in the symmetrical arm of the tee-junction. The design methodology of the elements and the architecture of the whole switch system are presented. We describe the scaling law that governs the relation between power handling capability and number of elements. The design of the active waveguide window is presented. The waveguide window is a silicon wafer with an array of four hundred PIN/NIP diodes covering the surface of the window. This waveguide window is located in an over-moded TE01 circular waveguide. The results of high power RF measurements of the active waveguide window are presented. The experiment is performed at power levels of tens of megawatts at X-band.

  12. Loss Analysis of High Power Stirling-Type Pulse Tube Cryocooler

    NASA Astrophysics Data System (ADS)

    Nakano, K.; Hiratsuka, Y.

    2015-12-01

    For the purpose of cooling high-temperature superconductor (HTS) devices, such as superconductor motors, superconducting magnetic energy storage (SMES) and current fault limiters, cryocoolers should be compact in size, light-weight, and have high efficiency and reliability. In order to meet the demand of HTS devices world-wide, the cryocooler needs to have COP efficiency >0.1. We have developed a high power Stirling-type pulse tube cryocooler (SPTC) with an in-line expander. The experimental results were reported in June 2012[1]. The cooling capacity was 210 W at 77 K and the minimum temperature was 37 K when the compressor input power was 3.8 kW. Accordingly, the COP was about 0.055. To further improve the efficiency, the energy losses in the cryocooler were analyzed. The experimental results and the numerical calculation results are reported in this paper.

  13. Enhancement of the crystalline Ge film growth by inductively coupled plasma-assisted pulsed DC sputtering.

    PubMed

    Kim, Eunkyeom; Han, Seung-Hee

    2014-11-01

    The effect of pulsed DC sputtering on the crystalline growth of Ge thin film was investigated. Ge thin films were deposited on the glass substrates using ICP-assisted pulsed DC sputtering. The Ge target was sputtered using asymmetric bipolar pulsed DC sputtering system with and without assistance of ICP source. The pulse frequency of 200 Hz and the pulse on time of 500 μsec (duty cycle = 10%) were kept during sputtering process. Crystal structures were studied from X-ray diffraction. The X-ray diffraction patterns clearly showed crystalline film structures. The Ge thin films with randomly oriented crystalline were obtained using pulsed DC sputtering without ICP, whereas they had well aligned (220) orientation crystalline using ICP source. Moreover, the combination of ICP assistance and pulsed DC sputtering enhanced the growth of crystalline Ge thin films without hydrogen and metal by in situ deposition. The structure and lattice of the films were studied from TEM images. The cross-sectional TEM images revealed the deposited Ge films with columnar structure.

  14. Using an active temporal compensating system to achieve the super-Gaussian pulses in high-power lasers

    NASA Astrophysics Data System (ADS)

    Wang, Yulei; Liu, Rui; Yuan, Hang; Li, Sensen; Liu, Zhaohong; Zhu, Xuehua; He, Weiming; Lv, Zhiwei

    2015-08-01

    In high-power solid-state laser, initiative pulse shaping can help improve the output laser's performance. The evaluation for output laser pulse is also incomplete. In this paper, we propose a method of initiative pulse shaping by using arbitrary waveform generator (AWG), and establish a relatively complete evaluation system for the output pulses shape simultaneously. It achieves the super-Gaussian pulse output with high SNR (signal-to-noise ratio). As a consequence, a square laser pulse with pulse adjustable width ~5ns, rising time 197ps is obtained. The power imbalance of the output square pulse is 3.72%. The similarity between the eight-order super-Gaussian pulse and the one we get from experiment reached 99%.

  15. Influence of the cubic spectral phase of high-power laser pulses on their self-phase modulation

    SciTech Connect

    Ginzburg, V N; Kochetkov, A A; Yakovlev, I V; Mironov, S Yu; Shaykin, A A; Khazanov, E A

    2016-02-28

    Spectral broadening of high-power transform-limited laser pulses under self-phase modulation in a medium with cubic nonlinearity is widely used to reduce pulse duration and to increase its power. It is shown that the cubic spectral phase of the initial pulse leads to a qualitatively different broadening of its spectrum: the spectrum has narrow peaks and broadening decreases. However, the use of chirped mirrors allows such pulses to be as effectively compressed as transform-limited pulses. (nonlinear optical phenomena)

  16. Novel high-frequency, high-power, pulsed oscillator based on a transmission line transformer.

    PubMed

    Burdt, R; Curry, R D

    2007-07-01

    Recent analysis and experiments have demonstrated the potential for transmission line transformers to be employed as compact, high-frequency, high-power, pulsed oscillators with variable rise time, high output impedance, and high operating efficiency. A prototype system was fabricated and tested that generates a damped sinusoidal wave form at a center frequency of 4 MHz into a 200 Omega load, with operating efficiency above 90% and peak power on the order of 10 MW. The initial rise time of the pulse is variable and two experiments were conducted to demonstrate initial rise times of 12 and 3 ns, corresponding to a spectral content from 4-30 and from 4-100 MHz, respectively. A SPICE model has been developed to accurately predict the circuit behavior and scaling laws have been identified to allow for circuit design at higher frequencies and higher peak power. The applications, circuit analysis, test stand, experimental results, circuit modeling, and design of future systems are all discussed.

  17. Frequency doubled high-power disk lasers in pulsed and continuous-wave operation

    NASA Astrophysics Data System (ADS)

    Weiler, Sascha; Hangst, Alexander; Stolzenburg, Christian; Zawischa, Ivo; Sutter, Dirk; Killi, Alexander; Kalfhues, Steffen; Kriegshaeuser, Uwe; Holzer, Marco; Havrilla, David

    2012-03-01

    The disk laser with multi-kW output power in infrared cw operation is widely used in today's manufacturing, primarily in the automotive industry. The disk technology combines high power (average and/or peak power), excellent beam quality, high efficiency and high reliability with low investment and operating costs. Additionally, the disk laser is ideally suited for frequency conversion due to its polarized output with negligible depolarization losses. Laser light in the green spectral range (~515 nm) can be created with a nonlinear crystal. Pulsed disk lasers with green output of well above 50 W (extracavity doubling) in the ps regime and several hundreds of Watts in the ns regime with intracavity doubling are already commercially available whereas intracavity doubled disk lasers in continuous wave operation with greater than 250 W output are in test phase. In both operating modes (pulsed and cw) the frequency doubled disk laser offers advantages in existing and new applications. Copper welding for example is said to show much higher process reliability with green laser light due to its higher absorption in comparison to the infrared. This improvement has the potential to be very beneficial for the automotive industry's move to electrical vehicles which requires reliable high-volume welding of copper as a major task for electro motors, batteries, etc.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Interaction of a high-power laser pulse with supercritical-density porous materials

    SciTech Connect

    Gus'kov, Sergei Yu; Rozanov, Vladislav B; Caruso, A; Strangio, C

    2000-03-31

    The properties of a nonequilibrium plasma produced by high-power laser pulses with intensities I{sub L} {approx} 10{sup 14}-10{sup 15} W cm{sup -2} irradiating plane targets made of a porous material are investigated. The mean density of matter in targets was substantially higher than the critical plasma density corresponding to a plasma resonance. The density of porous material was {rho}{sub a} {approx} 1 - 20 mg cm{sup -3}, whereas the critical density at the wavelength of incident radiation was {rho}{sub cr} {approx} 3 mg cm{sup -3}. An anomalously high absorption (no less than 80%) of laser radiation inside a target was observed. Within the first 3 - 4 ns of interaction, the plasma flow through the irradiated target surface in the direction opposite of the direction of the laser beam was noticeably suppressed. Only about 5% of absorbed laser energy was transformed into the energy of particles in this flow during the laser pulse. Absorbed energy was stored as the internal plasma energy at this stage (the greenhouse effect). Then, this energy was transformed, similar to a strong explosion, into the energy of a powerful hydrodynamic flow of matter surrounding the absorption region. The specific features of the formation and evolution of a nonequilibrium laser-produced plasma in porous media are theoretically analysed. This study allows the results of experiments to be explained. In particular, we investigated absorption of laser radiation in the bulk of a target, volume evaporation of porous material, the expansion of a laser-produced plasma inside the pores, stochastic collisions of plasma flows, and hydrothermal energy dissipation. These processes give rise to long-lived oscillations of plasma density and lead to the formation of an internal region where laser radiation is absorbed. (invited paper)

  20. Measurement of electromagnetic pulses generated during interactions of high power lasers with solid targets

    NASA Astrophysics Data System (ADS)

    De Marco, M.; Krása, J.; Cikhardt, J.; Pfeifer, M.; Krouský, E.; Margarone, D.; Ahmed, H.; Borghesi, M.; Kar, S.; Giuffrida, L.; Vrana, R.; Velyhan, A.; Limpouch, J.; Korn, G.; Weber, S.; Velardi, L.; Delle Side, D.; Nassisi, V.; Ullschmied, J.

    2016-06-01

    A target irradiated with a high power laser pulse, blows off a large amount of charge and as a consequence the target itself becomes a generator of electromagnetic pulses (EMP) owing to high return current flowing to the ground through the target holder. The first measurement of the magnetic field induced by the neutralizing current reaching a value of a few kA was performed with the use of an inductive target probe at the PALS Laser Facility (Cikhardt et al. Rev. Sci. Instrum. 85 (2014) 103507). A full description of EMP generation should contain information on the spatial distribution and temporal variation of the electromagnetic field inside and outside of the interaction chamber. For this reason, we consider the interaction chamber as a resonant cavity in which different modes of EMP oscillate for hundreds of nanoseconds, until the EMP is transmitted outside through the glass windows and EM waves are attenuated. Since the experimental determination of the electromagnetic field distribution is limited by the number of employed antennas, a mapping of the electromagnetic field has to be integrated with numerical simulations. Thus, this work reports on a detailed numerical mapping of the electromagnetic field inside the interaction chamber at the PALS Laser Facility (covering a frequency spectrum from 100 MHz to 3 GHz) using the commercial code COMSOL Multiphysics 5.2. Moreover we carried out a comparison of the EMP generated in the parallelepiped-like interaction chamber used in the Vulcan Petawatt Laser Facility at the Rutherford Appleton Laboratory, against that produced in the spherical interaction chamber of PALS.

  1. Emphasis on High Power Lithium Ion Technology for Pulse-Load Operations: Terrestrial Developments Potential Benefits to Space Application

    NASA Astrophysics Data System (ADS)

    Fusalba, Florence; Chami, Marianne; Rey, Marlene; Moreau, Gilles; Reynier, Yvan; Azais, Philippe

    2014-08-01

    Currently Li-ion batteries are preferred to supply space missions owing to their large energy density. However, these batteries are designed for standard missions without high-power pulsed payloads, therefore for low C-rates profiles, and do not answer the needs of high- power space applications. More enhanced power sources compatible with extended thermal environment are therefore needed for some space applications like next generation launchers or radar satellites. It is believed that synergy between terrestrial and space sectors could foster the avoidance of multiple financing for the development of similar technologies and systems, as well as dual-use of facilities, providing some real applications for synergy. CEA experienced terrestrial requirements for Hybrid Electric Vehicle applications, start & stop, e-buses and other larger vehicles. In this frame, materials especially designed for high power needs, new cells conception and recently hybrid supercapacitors developments at CEA are discussed as potential solutions for space high power feature.

  2. Characterization of energetic and thermalized sputtered atoms in pulsed plasma using time-resolved tunable diode-laser induced fluorescence

    SciTech Connect

    Desecures, M.; Poucques, L. de; Easwarakhanthan, T.; Bougdira, J.

    2014-11-03

    In this work, a time-resolved tunable diode-laser (DL) induced fluorescence (TR-TDLIF) method calibrated by absorption spectroscopy has been developed in order to determine atom and flux velocity distribution functions (AVDF and FVDF) of the energetic and the thermalized atoms in pulsed plasmas. The experimental set-up includes a low-frequency (∼3 Hz) and high spectral-resolution DL (∼0.005 pm), a fast rise-time pulse generator, and a high power impulse magnetron sputtering (HiPIMS) system. The induced TR-TDLIF signal is recorded every 0.5 μs with a digital oscilloscope of a second-long trace. The technique is illustrated with determining the AVDF and the FVDF of a metastable state of the sputtered neutral tungsten atoms in the HiPIMS post-discharge. Gaussian functions describing the population of the four W isotopes were used to fit the measured TR-TDLIF signal. These distribution functions provide insight into transition from the energetic to thermalized regimes from the discharge onset. This technique may be extended with appropriate DLs to probe any species with rapidly changing AVDF and FVDF in pulsed and strongly oscillating plasmas.

  3. Means and method for characterizing high power, ultra short laser pulses in a real time, on line manner

    DOEpatents

    Veligdan, James T.

    1994-01-01

    An ultra short (<10 ps), high power laser pulse is temporally characterized by a system that uses a physical measurement of a wavefront that has been altered in a known manner. The system includes a first reflection switch to remove a portion of a pulse from a beam of pulses, then includes a second reflection switch, operating in a mode that is opposite to the first reflection switch, to slice off a portion of that removed portion. The sliced portion is then directed to a measuring device for physical measurement. The two reflection switches are arranged with respect to each other and with respect to the beam of ultra short pulses such that physical measurement of the sliced portion is related to the temporal measurement of the ultra short pulse by a geometric or trigonometric relationship. The reflection switches are operated by a control pulse that is directed to impinge on each of the reflection switches at a 90.degree. angle of incidence.

  4. Peak power tunable mid-infrared oscillator pumped by a high power picosecond pulsed fiber amplifier with bunch output

    NASA Astrophysics Data System (ADS)

    Wei, Kaihua; Guo, Yan; Lai, Xiaomin; Fan, Shanhui

    2016-07-01

    A high power mid-infrared optical parametric oscillator (OPO) with picosecond pulse bunch output is experimentally demonstrated. The pump source was a high power master oscillation power amplifier (MOPA) picosecond pulsed fiber amplifier. The seed of the MOPA was a gain-switched distributed Bragg reflector (DBR) laser diode (LD) with picosecond pulse operation at a high repetition rate. The seed laser was amplified to 50 W by two-stage pre-amplifiers and a large mode area (LMA) Yb fiber based power-amplifier. A fiber-pigtailed acousto-optic modulator with the first order diffraction transmission was inserted into the second pre-amplifier to form a picosecond pulse bunch train and to change the peak power simultaneously. The power-amplified pulse bunches were focused to pump a wavelength-tunable OPO for emitting high power mid-infrared laser. By adjusting the OPO cavity length, the maximum average idler powers obtained at 3.1, 3.3 and 3.5 μm were 7, 6.6 and 6.4 W respectively.

  5. High-power pulsed gyrotron for 300 GHz-band collective Thomson scattering diagnostics in the Large Helical Device

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Yuusuke; Saito, Teruo; Tatematsu, Yoshinori; Ikeuchi, Shinji; Manuilov, Vladimir N.; Kasa, Jun; Kotera, Masaki; Idehara, Toshitaka; Kubo, Shin; Shimozuma, Takashi; Tanaka, Kenji; Nishiura, Masaki

    2015-01-01

    A high-power pulse gyrotron was developed to generate a probe wave for 300 GHz-band collective Thomson scattering (CTS) diagnostics in the Large Helical Device. In this frequency range, avoiding mode competition is critical to realizing high-power and stable oscillation with a narrow frequency bandwidth. A moderately over-moded cavity was investigated to ensure sufficient isolation of a desired mode from neighbouring modes, and to achieve high power output simultaneously. A cavity with the TE14,2 operation mode, a triode electron gun with an intense laminar electron beam, and an internal mode convertor were designed to construct a prototype tube. It was experimentally observed that oscillation of the TE14,2 mode was strong enough for mode competition, and provided high power with sufficient stability. The oscillation characteristics associated with the electron beam properties were compared with the numerical characteristics to find an optimum operating condition. As a result, single-mode operation with maximum output power of 246 kW was demonstrated at 294 GHz with 65 kV/14 A electron beam, yielding efficiency of ˜27%. The radiation pattern was confirmed to be highly Gaussian. The duration of the 130 kW pulse, which is presently limited by the power supply, was extended up to 30 µs. The experimental results validate our design concept and indicate the potential for realizing a gyrotron with higher power and longer pulse toward practical use in 300 GHz CTS diagnostics.

  6. Generation of sub-50 fs pulses from a high-power Yb-doped fiber amplifier.

    PubMed

    Deng, Yujun; Chien, Ching-Yuan; Fidric, Bernard G; Kafka, James D

    2009-11-15

    We demonstrate the generation of 48 fs pulses with 18 W average power and 226 nJ of pulse energy from a Yb-doped fiber amplifier. The system uses a simple stretcher-free single-stage amplifier configuration operating in the parabolic pulse regime. The gain fiber length and pump wavelength are chosen in order to reduce the gain per unit length and generate both shorter pulses and higher pulse energy.

  7. Generation of high power pulsed terahertz radiation using a plasmonic photoconductive emitter array with logarithmic spiral antennas

    SciTech Connect

    Berry, Christopher W.; Hashemi, Mohammad R.; Jarrahi, Mona

    2014-02-24

    An array of 3 × 3 plasmonic photoconductive terahertz emitters with logarithmic spiral antennas is fabricated on a low temperature (LT) grown GaAs substrate and characterized in response to a 200 fs optical pump from a Ti:sapphire mode-locked laser at 800 nm wavelength. A microlens array is used to split and focus the optical pump beam onto the active area of each plasmonic photoconductive emitter element. Pulsed terahertz radiation with record high power levels up to 1.9 mW in the 0.1–2 THz frequency range is measured at an optical pump power of 320 mW. The record high power pulsed terahertz radiation is enabled by the use of plasmonic contact electrodes, enhancing the photoconductor quantum efficiencies, and by increasing the overall device active area, mitigating the carrier screening effect and thermal breakdown at high optical pump power levels.

  8. Nonlinear optical compression of high-power 10-μm CO2 laser pulses in gases and semiconductors

    NASA Astrophysics Data System (ADS)

    Pigeon, Jeremy; Tochitsky, Sergei; Joshi, Chan

    2017-03-01

    We review a series of experiments on nonlinear optical compression of high-power, picosecond, 10-µm CO2 laser pulses. Presented schemes include self-phase modulation in a Xe-filled hollow glass waveguide, self-phase modulation in GaAs followed by compression, and multiple four-wave mixing compression of a laser beat-wave in GaAs. The novel nonlinear optics and technical challenges uncovered through these experiments are discussed.

  9. On the possibility of using a corner-cube reflector in resonators of high-power repetitively pulsed lasers

    NASA Astrophysics Data System (ADS)

    Bulaev, V. D.; Gusev, V. S.; Lysenko, S. L.; Morozov, Yu B.; Poznyshev, A. N.

    2012-08-01

    An optical cavity with a highly reflecting mirror in the form of a hollow corner-cube reflector (CCR) made of uncooled plane metal mirrors, which, in combination with a plane semitransparent output mirror, ensures complete filling of the output laser beam aperture, is studied. It is shown that, both in the pulsed and repetitively pulsed regimes of high-power far- and mid-IR lasers, it is possible to achieve beam divergence close to the diffraction limit (taking into account the drift of the radiation pattern axis) and dependent only on the quality of surfaces and accuracy of alignment of the hollow CCR mirrors and the resonator.

  10. Interferometer design and controls for pulse stacking in high power fiber lasers

    NASA Astrophysics Data System (ADS)

    Wilcox, Russell; Yang, Yawei; Dahlen, Dar; Xu, Yilun; Huang, Gang; Qiang, Du; Doolittle, Lawrence; Byrd, John; Leemans, Wim; Ruppe, John; Zhou, Tong; Sheikhsofla, Morteza; Nees, John; Galvanauskas, Almantas; Dawson, Jay; Chen, Diana; Pax, Paul

    2017-03-01

    In order to develop a design for a laser-plasma accelerator (LPA) driver, we demonstrate key technologies that enable fiber lasers to produce high energy, ultrafast pulses. These technologies must be scalable, and operate in the presence of thermal drift, acoustic noise, and other perturbations typical of an operating system. We show that coherent pulse stacking (CPS), which requires optical interferometers, can be made robust by image-relaying, multipass optical cavities, and by optical phase control schemes that sense pulse train amplitudes from each cavity. A four-stage pulse stacking system using image-relaying cavities is controlled for 14 hours using a pulse-pattern sensing algorithm. For coherent addition of simultaneous ultrafast pulses, we introduce a new scheme using diffractive optics, and show experimentally that four pulses can be added while a preserving pulse width of 128 fs.

  11. High power laser pulses with voltage controlled durations of 400 - 1000 ps.

    PubMed

    Harth, F; Ulm, T; Lührmann, M; Knappe, R; Klehr, A; Hoffmann, Th; Erbert, G; L'huillier, J A

    2012-03-26

    We report on the generation and amplification of pulses with pulse widths of 400 - 1000 ps at 1064 nm. For pulse generation an ultra-fast semiconductor modulator is used that modulates a cw-beam of a DFB diode laser. The pulse lengths could be adjusted by the use of a voltage control. The pulses were amplified in a solid state Nd:YVO₄ regenerative amplifier to an average power of up to 47.7 W at 100 - 816 kHz.

  12. High-power widely tunable sub-20 fs Gaussian laser pulses for ultrafast nonlinear spectroscopy.

    PubMed

    Metzger, Bernd; Steinmann, Andy; Giessen, Harald

    2011-11-21

    We demonstrate the generation of widely tunable sub-20 fs Gaussian-shaped laser pulses using a grating-based 4-f pulse shaper and a liquid crystal spatial light modulator. Our pump source is an Yb:KGW solitary mode-locked oscillator at 44 MHz repetition rate which is coupled into a large mode area microstructured fiber to generate a broad spectrum from below 900 nm to above 1150 nm. These pulses are precompressed by a prism sequence and subsequently sent into the pulse shaper. We use the multiphoton intrapulse interference phase scan (MIIPS) for phase shaping and iterative amplitude optimization to achieve Gaussian-like tunable sub-20 fs pulses with output powers of up to 142 mW as well as nontunable pulses with 310 mW output power as short as 11.5 fs.

  13. Pulse repetition rate scaling from 5 to 100 GHz with a high-power semiconductor disk laser.

    PubMed

    Mangold, Mario; Zaugg, Christian A; Link, Sandro M; Golling, Matthias; Tilma, Bauke W; Keller, Ursula

    2014-03-10

    The high-power semiconductor laser studied here is a modelocked integrated external-cavity surface emitting laser (MIXSEL), which combines the gain of vertical-external-cavity surface-emitting lasers (VECSELs) with the saturable absorber of a semiconductor saturable absorber mirror (SESAM) in a single semiconductor layer stack. The MIXSEL concept allows for stable and self-starting fundamental passive modelocking in a simple straight cavity and the average power scaling is based on the semiconductor disk laser concept. Previously record-high average output power from an optically pumped MIXSEL was demonstrated, however the long pulse duration of 17 ps prevented higher pulse repetition rates and many interesting applications such as supercontinuum generation and broadband frequency comb generation. With a novel MIXSEL structure, the first femtosecond operation was then demonstrated just recently. Here we show that such a MIXSEL can also support pulse repetition rate scaling from ≈5 GHz to >100 GHz with excellent beam quality and high average output power, by mechanically changing the cavity length of the linear straight cavity and the output coupler. Up to a pulse repetition rate of 15 GHz we obtained average output power >1 W and pulse durations <4 ps. Furthermore we have been able to demonstrate the highest pulse repetition rate from any fundamentally modelocked semiconductor disk laser with 101.2 GHz at an average output power of 127 mW and a pulse duration of 570 fs.

  14. Type-I cascaded quadratic soliton compression in lithium niobate: Compressing femtosecond pulses from high-power fiber lasers

    SciTech Connect

    Bache, Morten; Wise, Frank W.

    2010-05-15

    The output pulses of a commercial high-power femtosecond fiber laser or amplifier are typically around 300-500 fs with wavelengths of approximately 1030 nm and tens of microjoules of pulse energy. Here, we present a numerical study of cascaded quadratic soliton compression of such pulses in LiNbO{sub 3} using second-harmonic generation in a type-I phase-matching configuration. We find that because of competing cubic material nonlinearities, compression can only occur in the nonstationary regime, where group-velocity-mismatch-induced Raman-like nonlocal effects prevent compression to less than 100 fs. However, the strong group-velocity dispersion implies that the pulses can achieve moderate compression to durations of less than 130 fs in available crystal lengths. Most of the pulse energy is conserved because the compression is moderate. The effects of diffraction and spatial walk-off are addressed, and in particular the latter could become an issue when compressing such long crystals (around 10 cm long). We finally show that the second harmonic contains a short pulse locked to the pump and a long multi-picosecond red-shifted detrimental component. The latter is caused by the nonlocal effects in the nonstationary regime, but because it is strongly red-shifted to a position that can be predicted, we show that it can be removed using a bandpass filter, leaving a visible component of less than 100 fs at {lambda}=515 nm with excellent pulse quality.

  15. Effect of halo on high power laser pulse wake in underdense plasma

    NASA Astrophysics Data System (ADS)

    Pathak, Naveen; Zhidkov, Alexei; Masuda, Shinichi; Hosokai, Tomonao; Kodama, Ryosuke

    2016-11-01

    Strong disturbance in the wake of the laser pulses propagating in underdense plasma and consequent unstable electron acceleration by the wakefield can be provoked by pulse's halo, which always exists as a result of an imperfect optical focusing. When the power in the halo part exceeds a critical level for the self-focusing, it evolves in the plasma as an independent mode, which later gets coupled with the propagation of the central Gaussian spot of the pulse resulting in a novel instability. Here, this instability is investigated numerically via fully relativistic 3D particle-in-cell simulations and is shown to be partially suppressed by using plasma channels for pulse guiding.

  16. High-power pulsed thulium fiber oscillator modulated by stimulated Brillouin scattering

    SciTech Connect

    Tang, Yulong Xu, Jianqiu

    2014-01-06

    A pulsed ∼2-μm thulium-doped fiber laser passively modulated by distributed stimulated Brillouin scattering achieves 10.2 W average power and >100 kHz repetition rate with a very simple all-fiber configuration. The maximum pulse energy and peak power surpass 100 μJ and 6 kW, respectively. Another distinct property is that the pulse width is clamped around 17 ns at all power levels. All the average-power, pulse energy, and peak power show the highest values from passively modulated fiber lasers in all wavelength regions.

  17. Outlook for the use of microsecond plasma opening switches to generate high-power nanosecond current pulses

    NASA Astrophysics Data System (ADS)

    Dolgachev, G. I.; Maslennikov, D. D.; Ushakov, A. G.

    2006-12-01

    An analysis is made of the current break process in microsecond plasma opening switches and their possible application in high-current generators. Necessary conditions are determined for generating megavolt pulses in the erosion mode of a plasma opening switch with the gap insulated by an external magnetic field. Under these conditions, efficient sharpening of high-power submegampere current pulses can be achieved. The possibility of using plasma opening switches operating at voltages of 5 6 MV to generate X-ray and gamma emission is discussed. The main operating and design parameters of a six-module plasma opening switch with a current pulse amplitude of 3.7 MA and voltage of 4 6 MV for use in the MOL generator, which is the prototype of one of the 24 modules of the projected Baikal multimegajoule generator, are estimated by using the available scalings.

  18. High-power pulsed and CW diode-pumped mode-locked Nd:YAG lasers

    NASA Technical Reports Server (NTRS)

    Marshall, Larry R.; Hays, A. D.; Kaz, Alex; Kasinski, Jeff; Burnham, R. L.

    1991-01-01

    The operation of both pulsed and CW diode-pumped mode-locked Nd:YAG lasers are presented. The pulsed laser produced 1.0 mJ with pulsewidths of 90 psec at 20 Hz. The CW pumped laser produced 6 W output at 1.064 microns and 3 W output at 532 nm.

  19. Forward voltage short-pulse technique for measuring high power laser array junction temperature

    NASA Technical Reports Server (NTRS)

    Meadows, Byron L. (Inventor); Amzajerdian, Frazin (Inventor); Barnes, Bruce W. (Inventor); Baker, Nathaniel R. (Inventor)

    2012-01-01

    The present invention relates to a method of measuring the temperature of the P-N junction within the light-emitting region of a quasi-continuous-wave or pulsed semiconductor laser diode device. A series of relatively short and low current monitor pulses are applied to the laser diode in the period between the main drive current pulses necessary to cause the semiconductor to lase. At the sufficiently low current level of the monitor pulses, the laser diode device does not lase and behaves similar to an electronic diode. The voltage across the laser diode resulting from each of these low current monitor pulses is measured with a high degree of precision. The junction temperature is then determined from the measured junction voltage using their known linear relationship.

  20. The Development of the Electrically Controlled High Power RF Switch and Its Application to Active RF Pulse Compression Systems

    SciTech Connect

    Guo, Jiquan

    2008-12-01

    In the past decades, there has been increasing interest in pulsed high power RF sources for building high-gradient high-energy particle accelerators. Passive RF pulse compression systems have been used in many applications to match the available RF sources to the loads requiring higher RF power but a shorter pulse. Theoretically, an active RF pulse compression system has the advantage of higher efficiency and compactness over the passive system. However, the key component for such a system an element capable of switching hundreds of megawatts of RF power in a short time compared to the compressed pulse width is still an open problem. In this dissertation, we present a switch module composed of an active window based on the bulk effects in semiconductor, a circular waveguide three-port network and a movable short plane, with the capability to adjust the S-parameters before and after switching. The RF properties of the switch module were analyzed. We give the scaling laws of the multiple-element switch systems, which allow the expansion of the system to a higher power level. We present a novel overmoded design for the circular waveguide three-port network and the associated circular-to-rectangular mode-converter. We also detail the design and synthesis process of this novel mode-converter. We demonstrate an electrically controlled ultra-fast high power X-band RF active window built with PIN diodes on high resistivity silicon. The window is capable of handling multi-megawatt RF power and can switch in 2-300ns with a 1000A current driver. A low power active pulse compression experiment was carried out with the switch module and a 375ns resonant delay line, obtaining 8 times compression gain with a compression ratio of 20.

  1. High-power Waveguide Dampers for the Short-Pulse X-Ray Project at the Advanced Photon Source

    SciTech Connect

    Waldschmidt, G J; Liu, J; Middendorf, M E; Nassiri, A; Smith, T L; Wu, G; Henry, J; Mammosser, J D; Rimmer, R A; Wiseman, M

    2012-07-01

    High-power waveguide dampers have been designed and prototyped for the Short-Pulse X-ray (SPX) cavities at the Advanced Photon Source. The cavities will operate at 2.815 GHz and utilize the TM110 dipole mode. As a result, higher-order (HOM) and lower-order mode (LOM) in-vacuum dampers have been designed to satisfy the demanding broadband damping requirements in the APS storage ring. The SPX single-cell cavity consists of two WR284 waveguides for damping the HOMs and one WR284 waveguide for primarily damping the LOM where up to 2kW will be dissipated in the damping material. The damper designs and high-power experimental results will be discussed in this paper.

  2. Means and method for characterizing high power, ultra short laser pulses in a real time, on line manner

    DOEpatents

    Veligdan, J.T.

    1994-03-08

    An ultra short (<10 ps), high power laser pulse is temporally characterized by a system that uses a physical measurement of a wavefront that has been altered in a known manner. The system includes a first reflection switch to remove a portion of a pulse from a beam of pulses, then includes a second reflection switch, operating in a mode that is opposite to the first reflection switch, to slice off a portion of that removed portion. The sliced portion is then directed to a measuring device for physical measurement. The two reflection switches are arranged with respect to each other and with respect to the beam of ultra short pulses such that physical measurement of the sliced portion is related to the temporal measurement of the ultra short pulse by a geometric or trigonometric relationship. The reflection switches are operated by a control pulse that is directed to impinge on each of the reflection switches at a 90[degree] angle of incidence. 8 figures.

  3. High-power noise-like pulse generation using a 1.56-µm all-fiber laser system.

    PubMed

    Lin, Shih-Shian; Hwang, Sheng-Kwang; Liu, Jia-Ming

    2015-07-13

    We demonstrated an all-fiber, high-power noise-like pulse laser system at the 1.56-µm wavelength. A low-power noise-like pulse train generated by a ring oscillator was amplified using a two-stage amplifier, where the performance of the second-stage amplifier determined the final output power level. The optical intensity in the second-stage amplifier was managed well to avoid not only the excessive spectral broadening induced by nonlinearities but also any damage to the device. On the other hand, the power conversion efficiency of the amplifier was optimized through proper control of its pump wavelength. The pump wavelength determines the pump absorption and therefore the power conversion efficiency of the gain fiber. Through this approach, the average power of the noise-like pulse train was amplified considerably to an output of 13.1 W, resulting in a power conversion efficiency of 36.1% and a pulse energy of 0.85 µJ. To the best of our knowledge, these amplified pulses have the highest average power and pulse energy for noise-like pulses in the 1.56-µm wavelength region. As a result, the net gain in the cascaded amplifier reached 30 dB. With peak and pedestal widths of 168 fs and 61.3 ps, respectively, for the amplified pulses, the pedestal-to-peak intensity ratio of the autocorrelation trace remains at the value of 0.5 required for truly noise-like pulses.

  4. [The electroporation effects of high power pulse microwave and electromagnetic pulse irradiation on the membranes of cardiomyocyte cells and the mechanism therein involved].

    PubMed

    Deng, Hua; Wang, Dewen; Peng, Ruiyun; Wang, Shuiming; Chen, Jiankui; Zhang, Sa; Dong, Bo; Wang, Xiaomin

    2005-08-01

    Though there is ongoing public concern on potential hazards and risk of electromagnetic radiation, the bioeffects mechanism of electromagnetic fields remains obscure. Heart is one of the organs susceptive to electromagnetic fields (EMF). This study was designed to assess the influence of high power pulse microwave and electromagnetic pulse irradiation on cardiomyocytes, to explore the critical mechanism of electromagnetic fields, and to explain the regular course of injury caused by exposure to pulse EMF. Cultured cardiomyocytes were irradiated by high power pulse microwave and electromagnetic pulse first, then a series of apparatus including atom force microscope, laser scanning confocal microscope and flow cytometer were used to examine the changes of cell membrane conformation, structure and function. After irradiation, the cardiomyocytes pulsated slower or stop, the cells conformation was abnormal, the cells viability declined, and the percentage of apoptosis and necrosis increased significantly (P< 0.01). The cell membrane had pores unequal in size, and lost its penetration character. The concentration of Na+, K+, Ca2+, Cl-, Mg2+, Ca2+ and P3+ in cell culture medium increased significantly (P< 0.01). and the concentration of Ca2+ in cells ([Ca2+]i) decreased significantly (P<0.01). The results indicated that cardiomyocytes are susceptible to non-ionizing radiation. Pulse electromagnetic field can induce cardiomyocytes electroporation, and can do great damage to cells conformation, structure and function. Electroporation is one of the most critical mechanisms to explain the athermal effects of electromagnetic radiation.

  5. An ultra short pulse reconstruction software applied to the GEMINI high power laser system

    NASA Astrophysics Data System (ADS)

    Galletti, Mario; Galimberti, Marco; Hooker, Chris; Chekhlov, Oleg; Tang, Yunxin; Bisesto, Fabrizio Giuseppe; Curcio, Alessandro; Anania, Maria Pia; Giulietti, Danilo

    2016-09-01

    The GRENOUILLE traces of Gemini pulses (15 J, 30 fs, PW, shot per 20 s) were acquired in the Gemini Target Area PetaWatt at the Central Laser Facility (CLF), Rutherford Appleton Laboratory (RAL). A comparison between the characterizations of the laser pulse parameters made using two different types of algorithms: Video Frog and GRenouille/FrOG (GROG), was made. The temporal and spectral parameters came out to be in great agreement for the two kinds of algorithms. In this experimental campaign it has been showed how GROG, the developed algorithm, works as well as VideoFrog algorithm with the PetaWatt pulse class.

  6. Spatiotemporal evolution of high power laser pulses in relativistic magnetized inhomogeneous plasmas

    SciTech Connect

    Bokaei, B.; Niknam, A. R. Imani, E.

    2015-09-15

    In this work, the spatiotemporal evolution of Gaussian laser pulse propagated through a plasma is investigated in the presence of an external axial magnetic field. The coupled equations of self-focusing and self-compression are obtained via paraxial approximation by taking into account the relativistic nonlinearity. The effect of axial magnetic field on simultaneously relativistic self-focusing and self-compression of the laser pulse is studied for homogeneous and inhomogeneous plasmas. The results show that the simultaneous use of both axial magnetic field and density ramp-up leads to generate pulses with the smallest spot size and shortest compression length.

  7. On the Theory of High-Power Ultrashort Pulse Propagation in Raman-Active Media

    NASA Technical Reports Server (NTRS)

    Belenov, E. M.; Isakov, V. A.; Kanavin, A. P.; Smetanin, I. V.

    1996-01-01

    The propagation of an intense femtosecond pulse in a Raman-active medium is analyzed. An analytic solution which describes in explicit form the evolution of the light pulse is derived. The field of an intense light wave undergoes a substantial transformation as the wave propagates through the medium. The nature of this transformation can change over time scales comparable to the period of the optical oscillations. As a result, the pulse of sufficiently high energy divides into stretched and compressed domains where the field decreases and increases respectively.

  8. High-power diode-seeded thulium-doped fiber MOPA incorporating active pulse shaping

    NASA Astrophysics Data System (ADS)

    Shi, Hongxing; Tan, Fangzhou; Cao, Yi; Wang, Peng; Wang, Pu

    2016-10-01

    A turnkey fiber laser source generating high beam quality pulses with 240 W average power and arbitrary pulse shapes is presented in theory and experiment. It is based on semiconductor laser diode modulated by arbitrary waveform generator as a seed and polarization maintaining (PM) master oscillator power amplifier (MOPA) system to boost the pulse energy. Detailed experimental and theoretical studies are in a very good agreement. The polarization extinction ratio (PER) of system measured at maximum output power is beyond 17 dB with the excellent beam quality factor M 2 of 1.25.

  9. Low-temperature growth of low friction wear-resistant amorphous carbon nitride thin films by mid-frequency, high power impulse, and direct current magnetron sputtering

    SciTech Connect

    Bakoglidis, Konstantinos D. Schmidt, Susann; Garbrecht, Magnus; Ivanov, Ivan G.; Jensen, Jens; Greczynski, Grzegorz; Hultman, Lars

    2015-09-15

    The potential of different magnetron sputtering techniques for the synthesis of low friction and wear resistant amorphous carbon nitride (a-CN{sub x}) thin films onto temperature-sensitive AISI52100 bearing steel, but also Si(001) substrates was studied. Hence, a substrate temperature of 150 °C was chosen for the film synthesis. The a-CN{sub x} films were deposited using mid-frequency magnetron sputtering (MFMS) with an MF bias voltage, high power impulse magnetron sputtering (HiPIMS) with a synchronized HiPIMS bias voltage, and direct current magnetron sputtering (DCMS) with a DC bias voltage. The films were deposited using a N{sub 2}/Ar flow ratio of 0.16 at the total pressure of 400 mPa. The negative bias voltage, V{sub s}, was varied from 20 to 120 V in each of the three deposition modes. The microstructure of the films was characterized by high-resolution transmission electron microscopy and selected area electron diffraction, while the film morphology was investigated by scanning electron microscopy. All films possessed an amorphous microstructure, while the film morphology changed with the bias voltage. Layers grown applying the lowest substrate bias of 20 V exhibited pronounced intercolumnar porosity, independent of the sputter technique. Voids closed and dense films are formed at V{sub s} ≥ 60 V, V{sub s} ≥ 100 V, and V{sub s} = 120 V for MFMS, DCMS, and HiPIMS, respectively. X-ray photoelectron spectroscopy revealed that the nitrogen-to-carbon ratio, N/C, of the films ranged between 0.2 and 0.24. Elastic recoil detection analysis showed that Ar content varied between 0 and 0.8 at. % and increased as a function of V{sub s} for all deposition techniques. All films exhibited compressive residual stress, σ, which depends on the growth method; HiPIMS produces the least stressed films with values ranging between −0.4 and −1.2 GPa for all V{sub s}, while CN{sub x} films deposited by MFMS showed residual stresses up to −4.2

  10. Nonlinear dynamics of high-power ultrashort laser pulses: exaflop computations on a laboratory computer station and subcycle light bullets

    NASA Astrophysics Data System (ADS)

    Voronin, A. A.; Zheltikov, A. M.

    2016-09-01

    The propagation of high-power ultrashort light pulses involves intricate nonlinear spatio-temporal dynamics where various spectral-temporal field transformation effects are strongly coupled to the beam dynamics, which, in turn, varies from the leading to the trailing edge of the pulse. Analysis of this nonlinear dynamics, accompanied by spatial instabilities, beam breakup into multiple filaments, and unique phenomena leading to the generation of extremely short optical field waveforms, is equivalent in its computational complexity to a simulation of the time evolution of a few billion-dimensional physical system. Such an analysis requires exaflops of computational operations and is usually performed on high-performance supercomputers. Here, we present methods of physical modeling and numerical analysis that allow problems of this class to be solved on a laboratory computer boosted by a cluster of graphic accelerators. Exaflop computations performed with the application of these methods reveal new unique phenomena in the spatio-temporal dynamics of high-power ultrashort laser pulses. We demonstrate that unprecedentedly short light bullets can be generated as a part of that dynamics, providing optical field localization in both space and time through a delicate balance between dispersion and nonlinearity with simultaneous suppression of diffraction-induced beam divergence due to the joint effect of Kerr and ionization nonlinearities.

  11. 160 W high-power, high-efficiency, near-diffraction-limited beam quality all-fiber picosecond pulse laser

    NASA Astrophysics Data System (ADS)

    Sun, Chang; Ge, Tingwu; An, Na; Cao, Kang; Wang, Zhiyong

    2016-10-01

    We experimentally demonstrate a high-power, high-efficiency, near-diffraction-limited beam quality all-fiber picosecond pulse laser, which consists of a passively mode-locked seed laser and three-stage master power amplifiers. A repetition frequency multiplier and a high Yb-doped gain fiber with shorter length are utilized in the laser system to suppress the nonlinear effects and reduce the pulse broadening caused by dispersion. Moreover, the homemade light mode controllers based on a coiling and tapering fiber technique and the active fiber of the amplifier with a relatively small mode area are adopted to improve the beam quality. In addition, by experimentally adjusting the active fiber length, the optical conversion efficiency of the overall laser system can be optimized. Eventually, a 160 W high-power, high-efficiency, near-diffraction-limited picosecond pulse fiber laser is obtained, with the beam quality factor M2 at 1.12 and an optical conversion efficiency of the system of 75%.

  12. Long pulse acceleration of MeV class high power density negative H{sup −} ion beam for ITER

    SciTech Connect

    Umeda, N. Kojima, A.; Kashiwagi, M.; Tobari, H.; Hiratsuka, J.; Watanabe, K.; Dairaku, M.; Yamanaka, H.; Hanada, M.

    2015-04-08

    R and D of high power density negative ion beam acceleration has been carried out at MeV test facility in JAEA to realize ITER neutral beam accelerator. The main target is H{sup −} ion beam acceleration up to 1 MeV with 200 A/m{sup 2} for 60 s whose pulse length is the present facility limit. For long pulse acceleration at high power density, new extraction grid (EXG) has been developed with high cooling capability, which electron suppression magnet is placed under cooling channel similar to ITER. In addition, aperture size of electron suppression grid (ESG) is enlarged from 14 mm to 16 mm to reduce direct interception on the ESG and emission of secondary electron which leads to high heat load on the upstream acceleration grid. By enlarging ESG aperture, beam current increased 10 % at high current beam and total acceleration grid heat load reduced from 13 % to 10 % of input power at long pulse beam. In addition, heat load by back stream positive ion into the EXG is measured for the first time and is estimated as 0.3 % of beam power, while heat load by back stream ion into the source chamber is estimated as 3.5 ~ 4.0 % of beam power. Beam acceleration up to 60 s which is the facility limit, has achieved at 683 keV, 100 A/m{sup 2} of negative ion beam, whose energy density increases two orders of magnitude since 2011.

  13. Suppression of beam induced pulse shortening modes in high power RF generator TW output structures

    SciTech Connect

    Haimson, J.; Mecklenburg, B.

    1992-12-31

    Several different style 11.4 GHz relativistic klystrons, operating with beam pulse widths of 50 ns and using large aperture, tapered phase-velocity TW structures,` have recently demonstrated output RF power levels in the range of 100 to 300 MW without breakdown or pulse shortening. To extend this performance into the long pulse regime (1 {mu}s) or to demonstrate a threefold increase in output power by using higher currents, the existing TW circuit designs must be modified (a) to reduce the cavity maximum surface E-fields by a factor of 2 to 3, and (b) to elevate the current threshold values of the beam induced higher order modes (HOM) to ensure avoidance of RF pulse shortening and associated instabilities. A technique for substantially elevating this threshold current is described, and microwave data and photographs are presented showing the degree of HOM damping achieved in a recently constructed 11.4 GHz TW structure.

  14. Reliability of High Power Laser Diode Arrays Operating in Long Pulse Mode

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin; Meadows, Byron L.; Barnes, Bruce W.; Lockard, George E.; Singh, Upendra N.; Kavaya, Michael J.; Baker, Nathaniel R.

    2006-01-01

    Reliability and lifetime of quasi-CW laser diode arrays are greatly influenced by their thermal characteristics. This paper examines the thermal properties of laser diode arrays operating in long pulse duration regime.

  15. High-power pulsed diode-pumped Er:ZBLAN fiber laser.

    PubMed

    Gorjan, Martin; Petkovšek, Rok; Marinček, Marko; Čopič, Martin

    2011-05-15

    We report on the operation and performance of a gain-switched Er:ZBLAN fiber laser based on an active pulsed diode pump system. The produced laser pulses offer high peak powers while retaining the high average powers and efficiency of the cw regime. The measured pulse duration was about 300 ns and nearly independent of the pump repetition frequency. The maximum obtained 68 W of peak power is the highest reported, to our knowledge, for diode-pumped Er:ZBLAN fiber lasers, and the 2 W of average power at the repetition frequency of 100 kHz is 2 orders of magnitude higher than previously reported average power in a pulsed regime. The obtained slope efficiency was 34%.

  16. A broadly tunable autocorrelator for ultra-short, ultra-high power infrared optical pulses

    SciTech Connect

    Szarmes, E.B.; Madey, J.M.J.

    1995-12-31

    We describe the design of a crossed-beam, optical autocorrelator that uses an uncoated, birefringent beamsplitter to split a linearly polarized incident pulse into two orthogonally polarized pulses, and a Type II, SHG crystal to generate the intensity autocorrelation function. The uncoated beamsplitter accommodates extremely broad tunability while precluding any temporal distortion of ultrashort optical pulses at the dielectric interface, and the specific design provides efficient operation between 1 {mu}m and 4 {mu}m. Furthermore, the use of Type II SHG completely eliminates any single-beam doubling, so the autocorrelator can be operated at very shallow crossed-beam angles without generating a background pedestal. The autocorrelator has been constructed and installed in the Mark III laboratory at Duke University as a broadband diagnostic for ongoing compression experiments on the chirped-pulse FEL.

  17. Measurement and Generation of Ultra-High Power Fiber Laser Pulses by Coherent Combination

    DTIC Science & Technology

    2010-06-01

    through a Michelson interferometer and generated a double pulse as shown in Figure 10. Figure 10. Experimental setup for testing and calibrating...Measuring the Free Spectral Range of the VIPA etalons Using the spectral fringes generated by the Michelson interferometer , we can quantify the spectral...Testing the FROG To test the FROG, we again used use the double pulse from a Michelson interferometer , which yields a FROG trace unlikely to occur by

  18. Modeling of micrometeoric streams under the action of the high-power laser pulse on multicomponent polycrystal rocks

    NASA Astrophysics Data System (ADS)

    Timofeev, I. S.; Burdonskiy, I. N.; Goltsov, A. Yu; Leonov, A. G.; Makarov, K. N.; Yufa, V. N.

    2016-09-01

    The paper presents the analysis of interaction of the high-power laser pulse with multicomponent polycrystal rocks. Experiments were completed on a laser facility “Saturn” with intensity of 1010-1013 W/cm2. Structural analysis of the materials from the spall crater and from the plasma flame show significant differences. The article demonstrates experimental results of the spall formation moment depending on the thickness of the radiated target. The scale of damage to aluminium 6 pm thick foil at the rare side of the target is illustrated when it is hit by the andesite fragments from a spall crater.

  19. High power burst-mode optical parametric amplifier with arbitrary pulse selection.

    PubMed

    Pergament, M; Kellert, M; Kruse, K; Wang, J; Palmer, G; Wissmann, L; Wegner, U; Lederer, M J

    2014-09-08

    We present results from a unique burst-mode femtosecond non-collinear optical parametric amplifier (NOPA) under development for the optical - x-ray pump-probe experiments at the European X-Ray Free-Electron Laser Facility. The NOPA operates at a burst rate of 10 Hz, a duty cycle of 2.5% and an intra-burst repetition rate of up to 4.5 MHz, producing high fidelity 15 fs pulses at a center wavelength of 810 nm. Using dispersive amplification filtering of the super-continuum seed pulses allows for selectable pulse duration up to 75 fs, combined with a tuning range in excess of 100 nm whilst remaining nearly transform limited. At an intra-burst rate of 188 kHz the single pulse energy from two sequential NOPA stages reached 180 µJ, corresponding to an average power of 34W during the burst. Acousto- and electro-optic switching techniques enable the generation of transient free bursts of required length and the selection of arbitrary pulse sequences inside the burst.

  20. Influence of ionisation zone motion in high power impulse magnetron sputtering on angular ion flux and NbO x film growth

    NASA Astrophysics Data System (ADS)

    Franz, Robert; Clavero, César; Kolbeck, Jonathan; Anders, André

    2016-02-01

    The ion energies and fluxes in the high power impulse magnetron sputtering plasma from a Nb target were analysed angularly resolved along the tangential direction of the racetrack. A reactive oxygen-containing atmosphere was used as such discharge conditions are typically employed for the synthesis of thin films. Asymmetries in the flux distribution of the recorded ions as well as their energies and charge states were noticed when varying the angle between mass-energy analyser and target surface. More positively charged ions with higher count rates in the medium energy range of their distributions were detected in +\\mathbf{E}× \\mathbf{B} than in -\\mathbf{E}× \\mathbf{B} direction, thus confirming the notion that ionisation zones (also known as spokes or plasma bunches) are associated with moving potential humps. The motion of the recorded negatively charged high-energy oxygen ions was unaffected. Nb{{\\text{O}}x} thin films at different angles and positions were synthesised and analysed as to their structure and properties in order to correlate the observed plasma properties to the film growth conditions. The chemical composition and the film thickness varied with changing deposition angle, where the latter, similar to the ion fluxes, was higher in +\\mathbf{E}× \\mathbf{B} than in -\\mathbf{E}× \\mathbf{B} direction.

  1. Combining a molecular modelling approach with direct current and high power impulse magnetron sputtering to develop new TiO2 thin films for antifouling applications

    NASA Astrophysics Data System (ADS)

    Guillot, Jérôme; Lecoq, Elodie; Duday, David; Puhakka, Eini; Riihimäki, Markus; Keiski, Riitta; Chemin, Jean-Baptiste; Choquet, Patrick

    2015-04-01

    The accumulation of crystallization deposits at the surface of heat exchangers results in the increase of the heat transfer resistance and a drastic loss of efficiency. Coating surfaces with a thin film can limit the scale-surface adhesion force and thus the fouling process. This study compares the efficiency of TiO2 layers exhibiting various crystalline planes and microstructures to reduce the kinetic of fouling. Molecular modelling with density functional theory is first carried out to determine the energy of CaCO3 deposition on anatase (1 0 1), (0 0 4), and (2 0 0) surfaces as well as on a rutile (1 0 1) one. TiO2 thin films (thickness < 1 μm) are then synthesized by direct current and high power impulse magnetron sputtering (dcMS and HiPIMS respectively) in order to tune their crystallinity and microstructure. Lastly, the induction time to grow CaCO3 crystals at the surface of such materials is determined. Comparing the modelling and fouling results allows to draw general trends on the potential anti-scaling properties of TiO2 crystallized under various forms. Until now, such a comparison combining a theoretical approach with experimental fouling tests has never been reported in the literature.

  2. Train of high-power femtosecond pulses: Probe wave in a gas of prepared atoms

    NASA Astrophysics Data System (ADS)

    Muradyan, Gevorg; Muradyan, Atom Zh.

    2009-09-01

    We present a method for generating a regular train of ultrashort optical pulses in a prepared two-level medium. The train develops from incident monochromatic probe radiation traveling in a medium of atoms, which are in a quantum mechanical superposition of dressed internal states. In the frame of linear theory for the probe radiation, the energy of individual pulses is an exponentially growing function of atom density and of interaction cross section. Pulse repetition rate is determined by the pump field’s generalized Rabi frequency and can be around 1 THz and greater. We also show that the terms, extra to the dipole approximation, endow the gas by a new property: nonsaturating dependence of refractive index on dressing monochromatic field intensity. Contribution of these nonsaturating terms can be compatible with the main dipole approximation term contribution in the wavelength region of about ten micrometers (the range of CO2 laser) or larger.

  3. Initial operation of high power ICRF system for long pulse in EAST

    SciTech Connect

    Qin, C. M. Zhao, Y. P.; Zhang, X. J.; Wan, B. N.; Gong, X. Z.; Mao, Y. Z.; Yuan, S.; Chen, G.

    2015-12-10

    The ICRF heating system on EAST upgraded by active cooling aims for long pulse operation. In this paper, the main technical features of the ICRF system are described. One of a major challenges for long pulse operation is RF-edge interactions induced impurity production and heat loading. In EAST, ICRF antenna protections and Faraday screen bars damaged due to LH electron beam are found. Preliminary results for the analysis of the interaction between LHCD and ICRF antenna are discussed. Increase of metal impurities in the plasma during RF pulse and in a larger core radiation are also shown. These RF-edge interactions at EAST and some preliminary results for the optimizing RF performance will be presented.

  4. Methods for the shaping high-power picosecond laser pulses with a high-contrast ratio

    SciTech Connect

    Malinov, V. A.; Charukchev, A. V.; Chernov, V. N.; Nikitin, N. V.; Potapov, S. L.; Efanov, V. M.; Yarin, P. M.

    1998-02-20

    We present the performance of the electrooptical system based on four Pockels cells with 10 and 20 mm diameters, each of them is driving by its own drift step recovery diode pulse generator. We are developing electro-optic deflector system for CPA laser using two identical deflectors (diverging and converging) and three spatial filters. The results of numerical modeling of the time-dependent distributions of the intensity in the beam are presented. A peak-to-background intensity ratio more than five orders is achieved by this technique. We have developed a new pulse generator based on single drift step recovery diode producing two identical electrical pulses with output voltage up to 15 kV, FWHM of 1.5 ns, rise time of 0.7 ns and jitter of 100 ps at a 100 Hz repetition rate to electro-optic deflectors.

  5. Technology and engineering aspects of high power pulsed single longitudinal mode dye lasers

    NASA Astrophysics Data System (ADS)

    Rawat, V. S.; Mukherjee, Jaya; Gantayet, L. M.

    2015-09-01

    Tunable single mode pulsed dye lasers are capable of generating optical radiations in the visible range having very small bandwidths (transform limited), high average power (a few kW) at a high pulse repetition rate (a few tens of kHz), small beam divergence and relatively higher efficiencies. These dye lasers are generally utilized laser dyes dissolved in solvents such as water, heavy water, ethanol, methanol, etc. to provide a rapidly flowing gain medium. The dye laser is a versatile tool, which can lase either in the continuous wave (CW) or in the pulsed mode with pulse duration as small as a few tens of femtoseconds. In this review, we have examined the several cavity designs, various types of gain mediums and numerous types of dye cell geometries for obtaining the single longitudinal mode pulsed dye laser. Different types of cavity configuration, such as very short cavity, short cavity with frequency selective element and relatively longer cavity with multiple frequency selective elements were reviewed. These single mode lasers have been pumped by all kinds of pumping sources such as flash lamps, Excimer, Nitrogen, Ruby, Nd:YAG, Copper Bromide and Copper Vapor Lasers. The single mode dye lasers are either pumped transversely or longitudinally to the resonator axis. The pulse repletion rate of these pump lasers were ranging from a few Hz to a few tens of kHz. Physics technology and engineering aspects of tuning mechanism, mode hop free scanning and dye cell designs are also presented in this review. Tuning of a single mode dye laser with a resolution of a few MHz per step is a technologically challenging task, which is discussed here.

  6. Low-jitter high-power thyristor array pulse driver and generator

    DOEpatents

    Hanks, Roy L.

    2002-01-01

    A method and apparatus for generating low-jitter, high-voltage and high-current pulses for driving low impedance loads such as detonator fuses uses a MOSFET driver which, when triggered, discharges a high-voltage pre-charged capacitor into the primary of a toroidal current-multiplying transformer with multiple isolated secondary windings. The secondary outputs are suitable for driving an array of thyristors that discharge a precharged high-voltage capacitor and thus generating the required high-voltage and high-current pulse.

  7. High-power pulse repetitive HF(DF) laser with a solid-state pump generator

    SciTech Connect

    Velikanov, S D; Domazhirov, A P; Zaretskiy, N A; Kromin, A A; Sivachev, A A; Kharitonov, S V; Tsykin, V S; Shchurov, V V; Yutkin, I M; Kazantsev, S Yu; Kononov, I G; Podlesnykh, S V; Firsov, K N

    2015-11-30

    Operation of a repetitively pulsed electric-discharge HF(DF) laser with an all-solid-state pump generator based on FID switches is demonstrated. The energy stored in the pump generator capacitors was 880 J at an open-circuit voltage of 240 kV and a discharge pulse repetition rate of 25 Hz. The specific energy extractions were 3.8 and 3.4 J L{sup -1} for the HF and DF lasers, respectively. The possibilities of improving the output laser characteristics are discussed. (lasers)

  8. Post-filamentation propagation of high-power laser pulses in air in the regime of narrowly focused light channels

    NASA Astrophysics Data System (ADS)

    Geints, Yu. E.; Zemlyanov, A. A.; Ionin, A. A.; Mokrousova, D. V.; Seleznev, L. V.; Sinitsyn, D. V.; Sunchugasheva, E. S.

    2016-11-01

    We report the results of experimental and theoretical studies of the post-filamentation stage of nonlinear propagation of high-power pulsed radiation from a Ti : sapphire laser in air. We have for the first time obtained the experimental dependences of the angular divergence of specific spatially localised high-intensity light structures that are observed in the beam after its multiple filamentation (post-filamentation of channels) when varying the initial focusing of laser radiation and its energy. It is found that the angular divergence of the post-filamentation channels decreases with increasing pulse energy and reducing beam numerical aperture. The experimental dependences are qualitatively interpreted based on the diffraction model of the Bessel - Gaussian beam.

  9. Transport of ionized metal atoms in high-power pulsed magnetron discharges assisted by inductively coupled plasma

    SciTech Connect

    Konstantinidis, S.; Dauchot, J.P.; Ganciu, M.; Hecq, M.

    2006-01-09

    Transporting metallic ions from the magnetron cathode to the substrate is essential for an efficient thin-film deposition process. This letter examines how inductively coupled plasma superimposed onto a high-power pulsed magnetron discharge can influence the mobility of titanium ions. To this effect, time-resolved optical emission and absorption spectrometry are conducted and the current at the substrate is measured. With this new hybrid technique, ions are found to reach the substrate in two successive waves. Metal ions, only present in the second wave, are found to accelerate proportionally to the power supplied to the inductively coupled plasma. All the measurements in this study are made at 10 and 30 mTorr, with 10 {mu}s long pulses at the magnetron cathode.

  10. High-power all-fiber femtosecond chirped pulse amplification based on dispersive wave and chirped-volume Bragg grating.

    PubMed

    Sun, Ruoyu; Jin, Dongchen; Tan, Fangzhou; Wei, Shouyu; Hong, Chang; Xu, Jia; Liu, Jiang; Wang, Pu

    2016-10-03

    We report a high-power all-fiber-integrated femtosecond chirped pulse amplification system operating at 1064 nm, which consists of a dispersive wave source, a fiber stretcher, a series of ytterbium-doped amplifiers and a chirped volume Bragg grating (CVBG) compressor. The dispersive wave is generated by an erbium-doped mode-locked fiber laser with frequency shifted to the 1 μm region in a highly nonlinear fiber. With three stages of ytterbium-doped amplification, the average output power is scaled up to 125 W. Through CVBG, the pulse duration is compressed from 525 ps to 566 fs, the average output power of 107 W with a high compression efficiency of 86% is achieved, and the measured repetition rate is 17.57 MHz, corresponding to the peak power of 10.8 MW.

  11. Pulsed DC magnetron sputtered piezoelectric thin film aluminum nitride – Technology and piezoelectric properties

    SciTech Connect

    Stoeckel, C. Kaufmann, C.; Hahn, R.; Schulze, R.; Billep, D.; Gessner, T.

    2014-07-21

    Pulsed DC magnetron sputtered aluminum nitride (AlN) thin films are prepared on several seed layers and at different sputtering conditions. The piezoelectric c-axis (002) orientation of the AlN is analyzed with X-ray diffraction method. The transverse piezoelectric coefficient d{sub 31} is determined with a Laser-Doppler-Vibrometer at cantilevers and membranes by analytical calculations and finite element method. Additionally, thin film AlN on bulk silicon is used to characterize the longitudinal piezoelectric charge coefficient d{sub 33}.

  12. High-power pulsed diode laser for automotive scanning radar sensor

    NASA Astrophysics Data System (ADS)

    Kimura, Yuji; Matsushita, Noriyuki; Kato, Hisaya; Abe, Katsunori; Atsumi, Kinya

    2000-02-01

    High performance pulsed AlGaAs/GaAs wide stripe diode laser has been developed for the automotive distance-measuring scanning radar sensor. The laser diode is required high output power of 15 W and a long time reliability in spite of being used in a harsh environment such as wide temperature range, mechanical vibrations at the front bumper and so on. The device is designed by employing a multiple quantum well structure as an active layer for high output power with low drive current and high temperature operations. Moreover we reduce catastrophic optical damage power level and control the beam divergence angle by introducing optimized optical waveguide layers. In the chips bonding part, we developed a new thin film Au-Sn-Ni solder system. The bonding temperature can be lowered by using this system, whereby the thermal damage to the laser diode can be reduced. Furthermore, highly stable bonding is carried out by improving wetting ability in this system. We have achieved more than 22 W light output power at 20A pulse current under room temperature and more than 16 W light output power under 90 degrees Celsius. High reliability over 10,000 hours is performed for automotive use under pulsed operation at 90 degrees Celsius, 50 ns pulse width, 8 kHz frequency and 15 W light output power.

  13. Generating high-power short terahertz electromagnetic pulses with a multifoil radiator.

    PubMed

    Vinokurov, Nikolay A; Jeong, Young Uk

    2013-02-08

    We describe a multifoil cone radiator capable of generating high-field short terahertz pulses using short electron bunches. Round flat conducting foil plates with successively decreasing radii are stacked, forming a truncated cone with the z axis. The gaps between the foil plates are equal and filled with some dielectric (or vacuum). A short relativistic electron bunch propagates along the z axis. At sufficiently high particle energy, the energy losses and multiple scattering do not change the bunch shape significantly. When passing by each gap between the foil plates, the electron bunch emits some energy into the gap. Then, the radiation pulses propagate radially outward. For transverse electromagnetic waves with a longitudinal (along the z axis) electric field and an azimuthal magnetic field, there is no dispersion in these radial lines; therefore, the radiation pulses conserve their shapes (time dependence). At the outer surface of the cone, we have synchronous circular radiators. Their radiation field forms a conical wave. Ultrashort terahertz pulses with gigawatt-level peak power can be generated with this device.

  14. Advanced concepts for high-power, short-pulse CO2 laser development

    NASA Astrophysics Data System (ADS)

    Gordon, Daniel F.; Hasson, Victor; von Bergmann, Hubertus; Chen, Yu-hsin; Schmitt-Sody, A.; Penano, Joseph R.

    2016-06-01

    Ultra-short pulse lasers are dominated by solid-state technology, which typically operates in the near-infrared. Efforts to extend this technology to longer wavelengths are meeting with some success, but the trend remains that longer wavelengths correlate with greatly reduced power. The carbon dioxide (CO2) laser is capable of delivering high energy, 10 micron wavelength pulses, but the gain structure makes operating in the ultra-short pulse regime difficult. The Naval Research Laboratory and Air Force Research Laboratory are developing a novel CO2 laser designed to deliver ~1 Joule, ~1 picosecond pulses, from a compact gain volume (~2x2x80 cm). The design is based on injection seeding an unstable resonator, in order to achieve high energy extraction efficiency, and to take advantage of power broadening. The unstable resonator is seeded by a solid state front end, pumped by a custom built titanium sapphire laser matched to the CO2 laser bandwidth. In order to access a broader range of mid infrared wavelengths using CO2 lasers, one must consider nonlinear frequency multiplication, which is non-trivial due to the bandwidth of the 10 micron radiation.

  15. An Investigation into the Effect of High-Power Pulse IR Radiation on the Properties of Surfaces of CdxHg1-хTe Heteroepitaxial Layers

    NASA Astrophysics Data System (ADS)

    Boltar', K. O.; Burlakov, I. D.; Voitsekhovskii, А. V.; Sizov, А. L.; Sredin, V. G.; Talipov, N. Kh.; Shul'ga, S. А.

    2013-12-01

    The results of investigations into radiation modification of surfaces of Cd x Hg1- x Te (CMT) heteroepitaxial layers grown by molecular-beam and liquid-phase epitaxy (MBE- and LPE CMT HEL) affected by high-power pulse short-wavelength IR radiation are discussed. It is found that the surfaces of MBE CMT HEL and LPE CMT are enhanced by mercury as a result of high-power pulse short-wavelength IR radiation.

  16. High power visible light emitting diodes as pulsed excitation sources for biomedical photoacoustics

    PubMed Central

    Allen, Thomas J.; Beard, Paul C.

    2016-01-01

    The use of visible light emitting diodes (LEDs) as an alternative to Q-switched lasers conventionally used as photoacoustic excitation sources has been explored. In common with laser diodes, LEDs offer the advantages of compact size, low cost and high efficiency. However, laser diodes suitable for pulsed photoacoustic generation are typically available only at wavelengths greater than 750nm. By contrast, LEDs are readily available at visible wavelengths below 650nm where haemoglobin absorption is significantly higher, offering the prospect of increased SNR for superficial vascular imaging applications. To demonstrate feasibility, a range of low cost commercially available LEDs operating in the 420-620nm spectral range were used to generate photoacoustic signals in physiologically realistic vascular phantoms. Overdriving with 200ns pulses and operating at a low duty cycle enabled pulse energies up to 10µJ to be obtained with a 620nm LED. By operating at a high pulse repetition frequency (PRF) in order to rapidly signal average over many acquisitions, this pulse energy was sufficient to generate detectable signals in a blood filled tube immersed in an Intralipid suspension (µs’ = 1mm−1) at a depth of 15mm using widefield illumination. In addition, a compact four-wavelength LED (460nm, 530nm, 590nm, 620nm) in conjunction with a coded excitation scheme was used to illustrate rapid multiwavelength signal acquisition for spectroscopic applications. This study demonstrates that LEDs could find application as inexpensive and compact multiwavelength photoacoustic excitation sources for imaging superficial vascular anatomy. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. PMID:27446652

  17. Large-scale geophysical and geological-prospecting earth-crust investigation using high-power electromagnetic pulses

    NASA Astrophysics Data System (ADS)

    Velikhov, E. P.; Panchenko, V. P.

    2005-12-01

    The paper presents the concept and physical/technical prerequisites for the use of multi-megawatt electromagnetic pulses created, for instance, by autonomous MHD facilities of short-term operation (3--12 seconds), in fundamental and applied in-depth geophysical and geological research. Location of geological sites and research regions; circuits and parameters of emitting and detecting devices; unique pulse MHD facilities of 10--100 MWe capacity using solid (powder) fuel, created in Russia; conditions and methods of conducting large-scale experiments and trial methodical works, performed in the last 30 years by a cooperative group of Russian institute in various regions of Russia, Kyrghizia and Tajikistan, are described. Results of the following large-scale experiments and methodical works are presented: Oil and gas deposits' searching (Caspian depression, East Siberia); Study of electric conduction of sediments near and on the sea shelf (Kola peninsula); Electrical prospecting of ore deposits at depths of up to 10 km (Kola peninsula); Study of geo-electrical composition (section) of the earth-crust and upper mantle at the Ural (up to 40 km), and in the Baltic (up to 150 km); Forecasting of earthquakes using the effective electric resistance of earth-crust blocks up to 20 km deep (Tajikistan, Kirghizia); Seismic earth-crust "unloading", and changing the time-dependent distribution of the seismic activity under high-power electromagnetic impact; Impact on the ionosphere and spreading of ultra-low-frequency electromagnetic waves emitted by a high-power source. The possibilities and prospects of research dedicated to developing the technologies for electrical prospecting, sorting and outlining hydrocarbon deposits on the shelf, as well as to monitoring and studying the processes occurring in the earth-crust under artificial high-power electromagnetic impact in seismic regions, are discussed.

  18. Investigations of pulsed surface flashovers for the triggering of pseudospark high-power switches

    SciTech Connect

    Gortler, A.; Christiansen, J.; Frank, K. ); Deotzer, R. )

    1989-10-01

    Surface discharges over insulators in vacuum under rectangular high-voltage pulses are investigated. These discharges are among the methods used to trigger pseudospark switches. Low breakdown voltage and long lifetime are the requirements these insulators have to meet to be used as trigger materials. For this purpose the breakdown behavior of certain ceramics stressed by high-voltage pulses was investigated in an oil-free vacuum of 10{sup {minus}5} Pa. The erosion of the insulator by the discharge plasma was investigated with a scanning electron microscope (SEM). An evaluation of the measurement and a comparison of the properties of the investigated insulators show that SiN, Al{sub 2}O{sub 3}, and CaTiO{sub 3} have low breakdown voltages and exhibit the lowest erosion rates. First results obtained with these materials as trigger insulators in pseudospark switches are promising with regard to the achieved lifetimes.

  19. Ultraviolet conical emission produced by high-power femtosecond laser pulse in transparent media

    NASA Astrophysics Data System (ADS)

    Liu, Z.; Lu, X.; Liu, Q.; Sun, S.; Li, L.; Liu, X.; Ding, B.; Hu, B.

    2012-09-01

    In this work, supercontinuum conical emission (SC CE) accompanying the filamentation of powerful ultrashort laser pulse in BK7 glass and fused silica is studied. The SC CE is controlled by the laser power density and the sample thickness, and the minimum SC CE cut-off wavelength is about 309 nm in the BK7 glass and 237 nm in the fused silica. The angular distributions of the SC CE in the wavelength range less than 510 nm are measured by using a new method, and it cannot be explained by the Cerenkov emission theory but the unabridged X-Waves solution theory. Meanwhile numerical simulations of the propagation of femtosecond laser pulse in sample are performed to provide theoretical support to our results.

  20. High-power sub-two-cycle mid-infrared pulses at 100 MHz repetition rate

    NASA Astrophysics Data System (ADS)

    Pupeza, I.; Sánchez, D.; Zhang, J.; Lilienfein, N.; Seidel, M.; Karpowicz, N.; Paasch-Colberg, T.; Znakovskaya, I.; Pescher, M.; Schweinberger, W.; Pervak, V.; Fill, E.; Pronin, O.; Wei, Z.; Krausz, F.; Apolonski, A.; Biegert, J.

    2015-11-01

    Powerful coherent light with a spectrum spanning the mid-infrared (MIR) spectral range is crucial for a number of applications in natural as well as life sciences, but so far has only been available from large-scale synchrotron sources. Here we present a compact apparatus that generates pulses with a sub-two-cycle duration and with an average power of 0.1 W and a spectral coverage of 6.8-16.4 μm (at -30 dB). The demonstrated source combines, for the first time in this spectral region, a high power, a high repetition rate and phase coherence. The MIR pulses emerge via difference-frequency generation (DFG) driven by the nonlinearly compressed pulses of a Kerr-lens mode-locked ytterbium-doped yttrium-aluminium-garnet (Yb:YAG) thin-disc oscillator. The resultant 100 MHz MIR pulse train is hundreds to thousands of times more powerful than state-of-the-art frequency combs that emit in this range, and offers a high dynamic range for spectroscopy in the molecular fingerprint region and an ideal prerequisite for hyperspectral imaging as well as for the time-domain coherent control of vibrational dynamics.

  1. High-power, highly stable KrF laser with a 4-kHz pulse repetition rate

    SciTech Connect

    Borisov, V M; El'tsov, A V; Khristoforov, O B

    2015-08-31

    An electric-discharge KrF laser (248 nm) with an average output power of 300 W is developed and studied. A number of new design features are related to the use of a laser chamber based on an Al{sub 2}O{sub 3} ceramic tube. A high power and pulse repetition rate are achieved by using a volume discharge with lateral preionisation by the UV radiation of a creeping discharge in the form of a homogeneous plasma sheet on the surface of a plane sapphire plate. Various generators for pumping the laser are studied. The maximum laser efficiency is 3.1%, the maximum laser energy is 160 mJ pulse{sup -1}, and the pulse duration at half maximum is 7.5 ns. In the case of long-term operation at a pulse repetition rate of 4 kHz and an output power of 300 W, high stability of laser output energy (σ ≤ 0.7%) is achieved using an all-solid-state pump system. (lasers)

  2. High-power, highly stable KrF laser with a 4-kHz pulse repetition rate

    NASA Astrophysics Data System (ADS)

    Borisov, V. M.; El'tsov, A. V.; Khristoforov, O. B.

    2015-08-01

    An electric-discharge KrF laser (248 nm) with an average output power of 300 W is developed and studied. A number of new design features are related to the use of a laser chamber based on an Al2O3 ceramic tube. A high power and pulse repetition rate are achieved by using a volume discharge with lateral preionisation by the UV radiation of a creeping discharge in the form of a homogeneous plasma sheet on the surface of a plane sapphire plate. Various generators for pumping the laser are studied. The maximum laser efficiency is 3.1%, the maximum laser energy is 160 mJ pulse-1, and the pulse duration at half maximum is 7.5 ns. In the case of long-term operation at a pulse repetition rate of 4 kHz and an output power of 300 W, high stability of laser output energy (σ <= 0.7%) is achieved using an all-solid-state pump system.

  3. Development of negative ion extractor in the high-power and long-pulse negative ion source for fusion application

    SciTech Connect

    Kashiwagi, M. Umeda, N.; Tobari, H.; Kojima, A.; Yoshida, M.; Taniguchi, M.; Dairaku, M.; Maejima, T.; Yamanaka, H.; Watanabe, K.; Inoue, T.; Hanada, M.

    2014-02-15

    High power and long-pulse negative ion extractor, which is composed of the plasma grid (PG) and the extraction grid (EXG), is newly developed toward the neutral beam injector for heating and current drive of future fusion machines such as ITER, JT-60 Super Advanced and DEMO reactor. The PG is designed to enhance surface production of negative ions efficiently by applying the chamfered aperture. The efficiency of the negative ion production for the discharge power increased by a factor of 1.3 against that of the conventional PG. The EXG is also designed with the thermal analysis to upgrade the cooling capability for the long pulse operation of >1000 s required in ITER. Though the magnetic field for electron suppression is reduced to 0.75 of that in the conventional EXG due to this upgrade, it was experimentally confirmed that the extracted electron current can be suppressed to the allowable level for the long pulse operation. These results show that newly developed extractor has the high potential for the long pulse extraction of the negative ions.

  4. Industrial grade fiber-coupled laser systems delivering ultrashort high-power pulses for micromachining

    NASA Astrophysics Data System (ADS)

    Pricking, Sebastian; Welp, Petra; Overbuschmann, Johannes; Nutsch, Sebastian; Gebs, Raphael; Fleischhaker, Robert; Kleinbauer, Jochen; Wolf, Martin; Budnicki, Aleksander; Sutter, Dirk H.; Killi, Alexander; Mielke, Michael

    2016-03-01

    We report on an industrial fiber-delivered laser system producing ultra-short pulses in the range of a few picoseconds down to a few hundred femtoseconds with high average power suitable for high-precision micromachining. The delivery fiber is a hollow-core photonic crystal fiber with a Kagomé shaped lattice and a hypocycloid core wall enabling the guiding of laser radiation over several meters with exceptionally low losses and preservation of high beam quality (M2<1.3). The mode-matching and coupling optics are integrated into the laser head providing a compact footprint without the need for external boxes. The laser head is carefully designed regarding its thermo-mechanical properties to allow a highly reliable coupling stability. The exchangeable delivery fiber is packaged using Trumpf's well established LLK-D connectors which offer a very high mechanical precision, the possibility to add water cooling, as well as full featured safety functions. The fiber is hermetically sealed and protected by a robust but flexible shield providing bend protection and break detection. We show the linear and nonlinear optical properties of the transported laser radiation and discuss its feasibility for pulse compression. Measurements are supported by simulation of pulse propagation by solving the nonlinear Schrödinger equation implementing the split-step Fourier method. In addition, mode properties are measured and confirmed by finite element method simulations. The presented industrial laser system offers the known advantages of ultra-short pulses combined with the flexibility of fiber delivery yielding a versatile tool perfectly suitable for all kinds of industrial micromachining applications.

  5. High Power Laser Cutting of Fiber Reinforced Thermoplastic Polymers with cw- and Pulsed Lasers

    NASA Astrophysics Data System (ADS)

    Schneider, F.; Wolf, N.; Petring, D.

    Glass fiber and carbon fiber reinforced polymers with thermoplastic matrix enable high volume production with short cycle times. Cutting and trimming operations in these production chains require the use of high average laser power for an efficient cutting speed, but employment of high laser power runs the risk to induce a wide heat affected zone (HAZ). This paper deals with investigations with cw and ns-pulsed CO2-laser radiation in the kilowatt range in single-pass and multiple-pass processes. Using multi-pass processing at high processing speeds of 100 m/min and above a reduced heat affected zone in the range of 100 μm to 200 μm could be achieved by the ns-pulsed radiation. With cw radiation at the same average power of 1 kW however, the HAZ was 300-400 μm. Also employing ns-pulses in the kW-range average power leads to heat accumulation in the material. Small HAZ were obtained with sufficient break times between subsequent passes.

  6. Photocatalytic activity of bipolar pulsed magnetron sputter deposited TiO2/TiWOx thin films

    NASA Astrophysics Data System (ADS)

    Weng, Ko-Wei; Hu, Chung-Hsuan; Hua, Li-Yu; Lee, Chin-Tan; Zhao, Yu-Xiang; Chang, Julian; Yang, Shu-Yi; Han, Sheng

    2016-08-01

    Titanium oxide films were formed by sputtering and then TiWOx films were deposited by bipolar pulsed magnetron sputtering with pure titanium and tungsten metal targets. The sputtering of titanium oxide with tungsten enhanced the orientation of the TiO2 (1 0 1) plane of the specimen assemblies. The main varying parameter was the tungsten pulse power. Titanium oxide sputtered with tungsten using a pulsing power of 50 W exhibited a superior hydrophilic property, and a contact angle of 13.1°. This fabrication conditions maximized the photocatalytic decomposition of methylene blue solution. The mechanism by which the titanium oxide was sputtered with tungsten involves the photogeneration of holes and electron traps, inhibiting the hole-electron recombination, enhancing hydrophilicity and reducing the contact angle.

  7. Penetration and propagation into biological matter and biological effects of high-power ultra-wideband pulses: a review.

    PubMed

    Schunck, Thérèse; Bieth, François; Pinguet, Sylvain; Delmote, Philippe

    2016-01-01

    Systems emitting ultra-wideband high power microwave (HP/UWB) pulses are developed for military and civilian applications. HP/UWB pulses typically have durations on the order of nanoseconds, rise times of picoseconds and amplitudes around 100 kV m(-1). This article reviews current research on biological effects from HP/UWB exposure. The different references were classified according to endpoints (cardiovascular system, central nervous system, behavior, genotoxicity, teratology …). The article also reviews the aspects of mechanisms of interactions and tissue damage as well as the numerical work that has been done for studying HP/UWB pulse propagation and pulse energy deposition inside biological tissues. The mechanisms proposed are the molecular conformation change, the modification of chemical reaction rates, membrane excitation and breakdown and direct electrical forces on cells or cell constituents, and the energy deposition. As regards the penetration of biological matter and the deposited energy, mainly computations were published. They have shown that the EM field inside the biological matter is strongly modified compared to the incident EM field and that the energy absorption for HP/UWB pulses occurs in the same way as for continuous waves. However, the energy carried by a HP/UWB pulse is very low and the deposited energy is low. The number of published studies dealing with the biological effects is small and only a few pointed out slight effects. It should be further noted that the animal populations used in the studies were not always large, the statistical analyses not always relevant and the teams involved in this research rather limited in number.

  8. Short spatial filters with spherical lenses for high-power pulsed lasers

    SciTech Connect

    Burdonov, K F; Soloviev, A A; Shaikin, A A; Potemkin, A K; Egorov, A S

    2013-11-30

    We report possible employment of short spatial filters based on spherical lenses in a pulsed laser source (neodymium glass, 300 J, 1 ns). The influence of the spherical aberration on the quality of output radiation and coefficient of conversion to the second harmonics is studied. The ultra-short aberration spatial filter of length 1.9 m with an aperture of 122 mm is experimentally tested. A considerable shortening of multi-cascade pump lasers for modern petawatt laser systems is demonstrated by the employment of short spatial filters without expensive aspherical optics. (elements of laser systems)

  9. High power CW (16W) and pulse (145W) laser diodes based on quantum well heterostructures.

    PubMed

    Tarasov, Ilya S; Pikhtin, Nikita A; Slipchenko, Sergey O; Sokolova, Zinaida N; Vinokurov, Dmitry A; Borschev, Kirill S; Kapitonov, Vladimir A; Khomylev, Maxim A; Leshko, Andrey Yu; Lyutetskiy, Andrey V; Stankevich, Alexey L

    2007-04-01

    We suggested and experimentally confirmed the effective method of internal optical loss reduction by high order mode suppression in a separate confinement quantum well laser heterostructure with asymmetric ultra thick waveguide. Manufacturing of InGaAs/GaAs/AlGaAs laser heterostructure with a 1.7 microm-thick asymmetric waveguide allowed attaining super low value of internal optical loss alphai=0.34 cm-1 preserving high efficiency and fundamental transverse mode operation. Record-high 16 W continuous wave (CW) and 145 W pulse room temperature front facet output optical power and 74% wallplug efficiency were attained in 100-microm-aperture 1.06-microm-emitting laser diodes with 3 mm cavity length.

  10. Thermal properties of borate crystals for high power optical parametric chirped-pulse amplification.

    PubMed

    Riedel, R; Rothhardt, J; Beil, K; Gronloh, B; Klenke, A; Höppner, H; Schulz, M; Teubner, U; Kränkel, C; Limpert, J; Tünnermann, A; Prandolini, M J; Tavella, F

    2014-07-28

    The potential of borate crystals, BBO, LBO and BiBO, for high average power scaling of optical parametric chirped-pulse amplifiers is investigated. Up-to-date measurements of the absorption coefficients at 515 nm and the thermal conductivities are presented. The measured absorption coefficients are a factor of 10-100 lower than reported by the literature for BBO and LBO. For BBO, a large variation of the absorption coefficients was found between crystals from different manufacturers. The linear and nonlinear absorption coefficients at 515 nm as well as thermal conductivities were determined for the first time for BiBO. Further, different crystal cooling methods are presented. In addition, the limits to power scaling of OPCPAs are discussed.

  11. Lack of direct DNA damage in human blood leukocytes and lymphocytes after in vitro exposure to high power microwave pulses.

    PubMed

    Chemeris, N K; Gapeyev, A B; Sirota, N P; Gudkova, O Yu; Tankanag, A V; Konovalov, I V; Buzoverya, M E; Suvorov, V G; Logunov, V A

    2006-04-01

    Currently, the potential genotoxicity of high power microwave pulses (HPMP) is not clear. Using the alkaline single cell gel electrophoresis assay, also known as the alkaline comet assay, we studied the effects of HPMP (8.8 GHz, 180 ns pulse width, peak power 65 kW, pulse repetition frequency 50 Hz) on DNA of human whole-blood leukocytes and isolated lymphocytes. The cell suspensions were exposed to HPMP for 40 min in a rectangular waveguide. The average SAR calculated from the temperature kinetics was about 1.6 kW/kg (peak SAR was about 300 MW/kg). The steady-state temperature rise in the 50 microl samples exposed to HPMP was 3.5 +/- 0.1 degrees C. In independent experiments, we did not find any statistically significant DNA damage manifested immediately after in vitro HPMP exposure of human blood leukocytes or lymphocytes or after HPMP exposure of leukocytes subsequently incubated at 37 degrees C for 30 min. Our results indicate that HPMP under the given exposure conditions did not induce DNA strand breaks, alkali-labile sites, and incomplete excision repair sites, which could be detected by the alkaline comet assay.

  12. Spiking suppression of high power QCW pulse 1319 nm Nd:YAG laser with different intracavity doublers

    NASA Astrophysics Data System (ADS)

    Bian, Qi; Zuo, Jun-Wei; Guo, Chuan; Xu, Chang; Shen, Yu; Zong, Nan; Bo, Yong; Peng, Qin-Jun; Chen, Hong-Bin; Cui, Da-Fu; Xu, Zu-Yan

    2016-09-01

    We describe the results of our efforts in suppressing spiking of a high power, high beam quality 1319 nm Nd:YAG microsecond-pulse laser with three different intracavity frequency doublers. The 1319 nm laser is generated by a quasi-continuous-wave diode-pumped Nd:YAG ring laser system. One potassium titanyl phosphate (KTP), two KTPs and one lithium triborate (LBO) as frequency doublers are installed in the ring resonator and tested, respectively. At 800 Hz repetition rate, with a pulse width of 100 µs, performances of spiking suppression for each case are observed. The average output power are 23.6 W, 22.7 W and 23.4 W with beam quality factors of M 2  =  2.21, 1.28 and 1.25 for one KTP, two KTPs and one LBO, respectively. The corresponding brightness are 270 MW/(cm2·sr), 780 MW/(cm2·sr) and 860 MW/(cm2·sr). With better beam quality, higher brightness, and easier maintainability, the LBO is the best option of the three. A laser rate equation model including the insertion loss of the doubler is applied for theoretical analysis of the output temporal pulse shape and power, and the simulated results agree well with the experimental data.

  13. Thermal damage suppression of a black phosphorus saturable absorber for high-power operation of pulsed fiber lasers

    NASA Astrophysics Data System (ADS)

    Lee, Donghyun; Park, Kichul; Debnath, Pulak C.; Kim, Inho; Song, Yong-Won

    2016-09-01

    Recent studies of black phosphorus (BP) have shown its future potential in the field of photonics. We determined the optical damage threshold of BP at 21.8 dBm in a fiber ring laser cavity, and demonstrated the high-power operation capacity of an evanescent field interaction-based BP saturable absorber. The long-term stability of a passively mode-locked fiber laser with a saturable absorber operating at the optical power of 23.3 dBm was verified for 168 h without any significant performance degradation. The center wavelength, spectral width, and pulse width of the laser output are 1558.8 nm, 14.2 nm, and 805 fs, respectively.

  14. Thermal damage suppression of a black phosphorus saturable absorber for high-power operation of pulsed fiber lasers.

    PubMed

    Lee, Donghyun; Park, Kichul; Debnath, Pulak C; Kim, Inho; Song, Yong-Won

    2016-09-09

    Recent studies of black phosphorus (BP) have shown its future potential in the field of photonics. We determined the optical damage threshold of BP at 21.8 dBm in a fiber ring laser cavity, and demonstrated the high-power operation capacity of an evanescent field interaction-based BP saturable absorber. The long-term stability of a passively mode-locked fiber laser with a saturable absorber operating at the optical power of 23.3 dBm was verified for 168 h without any significant performance degradation. The center wavelength, spectral width, and pulse width of the laser output are 1558.8 nm, 14.2 nm, and 805 fs, respectively.

  15. High-power femtosecond-terahertz pulse induces a wound response in mouse skin

    NASA Astrophysics Data System (ADS)

    Kim, Kyu-Tae; Park, Jaehun; Jo, Sung Jin; Jung, Seonghoon; Kwon, Oh Sang; Gallerano, Gian Piero; Park, Woong-Yang; Park, Gun-Sik

    2013-08-01

    Terahertz (THz) technology has emerged for biomedical applications such as scanning, molecular spectroscopy, and medical imaging. Although a thorough assessment to predict potential concerns has to precede before practical utilization of THz source, the biological effect of THz radiation is not yet fully understood with scant related investigations. Here, we applied a femtosecond-terahertz (fs-THz) pulse to mouse skin to evaluate non-thermal effects of THz radiation. Analysis of the genome-wide expression profile in fs-THz-irradiated skin indicated that wound responses were predominantly mediated by transforming growth factor-beta (TGF-β) signaling pathways. We validated NFκB1- and Smad3/4-mediated transcriptional activation in fs-THz-irradiated skin by chromatin immunoprecipitation assay. Repeated fs-THz radiation delayed the closure of mouse skin punch wounds due to up-regulation of TGF-β. These findings suggest that fs-THz radiation initiate a wound-like signal in skin with increased expression of TGF-β and activation of its downstream target genes, which perturbs the wound healing process in vivo.

  16. Experiments on Self-Guiding Mechanisms of High Power Laser Pulses in a Plasma

    NASA Astrophysics Data System (ADS)

    Ralph, Joseph; Pak, Arthur; Marsh, Kenneth; Clayton, Christopher; Fang, Fang; Joshi, Chandrashekhar

    2007-11-01

    Recent 3D theory and PIC simulations in the blowout regime, wherein the pondermotive force of laser with a pulse length on the order of a plasma wavelength expels all electrons, has predicted a range of parameter space where stable laser propagation can occur [1]. In this theory, the density depression caused by electron blow out is the dominant mechism responsible for self-guiding. In this paper we examine experimentally and with PIC simulations laser beam guiding of a multi terwatt TiSapphire laser in a supersonic Helium gas jet. Gas jet density was varied from 2*E18 to to 2*E19 and the length of the plasma was varied from 2 to 5 mm using several gas jets with different diameters. Pondermotive and relativistic effects are considerd by varying laser and plasma parameters. Diagnostics include interferometric and Schlieren techniques. Images of the guided mode are taken at the exit of the gas jet. In addition, the forward images were sent to an imaging spectragraph to observe photon deceleration and deceleration [2]. [1] W. Lu, C. Huang, M. Zhou, and M. Tzoufras, F. S. Tsung, W. B. Mori, and T. Katsouleas, Phys. Plasmas 13, 056709 (2006) [2] A. E. Pak, J. E. Ralph, K. A. Marsh , C. E. Clayton, F. Fang and C. Joshi, These Procedings

  17. Simulation and initial experiments of a high power pulsed TEA CO2 laser

    NASA Astrophysics Data System (ADS)

    Torabi, R.; Saghafifar, H.; Koushki, A. M.; Ganjovi, A. A.

    2016-01-01

    In this paper, the output characteristics of a UV pin array pre-ionized TEA CO2 laser have been simulated and compared with the associated experimental data. In our simulation, a new theoretical model has been improved for transient behavior analysis of the discharge current pulse. The laser discharge tube was modeled by a nonlinear RLC electric circuit as a real model for electron density calculation. This model was coupled with a six-temperature model (6TM) in order to simulation dynamic emission processes of the TEA CO2 laser. The equations were solved numerically by the fourth order Runge-Kutta numerical method and some important variables such as current and voltage of the main discharge, resistance of the plasma column and electron density in the main discharge region, were calculated as functions of time. The effects of non-dissociation factor, rotational quantum number and output coupler reflectivity were also studied theoretically. The experimental and simulation results are in good agreement.

  18. High power and short pulse RF-excited CO II laser MOPA system for LLP EUV light source

    NASA Astrophysics Data System (ADS)

    Ariga, Tatsuya; Hoshino, Hideo; Miura, Taisuke; Endo, Akira

    2006-02-01

    Laser produced plasma EUV source is the candidate for high quality, 115 W EUV light source for the next generation lithography. Cost effective laser driver is the key requirement for the realization of the concept as a viable scheme. A CO II laser driven LPP system with a Xenon droplet target is therefore a promising light source alternative for EUV. We are developing a high power and high repetition rate CO II laser system to achieve 10 W intermediate focus EUV power. High conversion efficiency (CE) from the laser energy to EUV in-band energy is the primarily important issue for the concept to be realized. Numerical simulation analysis of a Xenon plasma target shows that a short laser pulse less than 15 ns is necessary to obtain a high CE by a CO II laser. This paper describes on the development of a CO II laser system with a short pulse length less than 15 ns, a nominal average power of a few kW, and a repetition rate of 100 kHz, based on RF-excited, axial flow CO II laser amplifiers. Output power of 1 kW has been achieved with a pulse length 15 ns at 100 kHz repletion rate in a small signal amplification condition with P(20) single line. The CO II laser system is reported on the conceptual design for a LPP EUV light source, and amplification performance in CW and short pulse using RF-excited axial flow lasers as amplifiers. Additional approach to increase the amplification efficiency is discussed.

  19. Experimental and theoretical studies of the fabrication of nanoparticles using a high power pulsed laser

    NASA Astrophysics Data System (ADS)

    Lee, Jae Myoung

    2000-10-01

    In this work, the laser-induced breakdown mechanism that leads to nanoparticle formation was investigated with optical experiments and theoretical simulations. In the experiments, pulsed-laser radiations at 1.06 μm was used to ablate 20 μm glass microspheres at three different fluences, 3, 6, and 12 J/cm2. A frequency-doubled laser beam illuminated the generated shockwave profile in a Schlieren configuration with delay times up to 30 ns. Shockwave images verified that breakdown in a 20 μm glass microsphere was initiated near the back surface due to internal focusing of the laser. The breakdown became the source for shockwave formation. Over the range of delays studied, shockwave velocity was approximately constant. The measured shockwave velocities were proportional to applied laser fluence and the velocity of the forward shockwave was faster than that of the backward (toward the laser source) shockwave. For longer times and propagation distances, however, we would expect the shockwave velocity to decrease. Therefore, measurements at longer optical delay times are needed to develop a complete shockwave propagation model for laser ablation of a glass microspheres. A hydrodynamic numerical code was developed to further investigate the optical breakdown and shockwave initiation process. It included a two fluid model (electrons and ions) to account for energy exchange, energy radiation, and thermal conduction due to interactions between and among electrons and ions. A quotidian equation of state was implemented to overcome nonphysical data from the SESAME equation of data tables, especially in the low temperature and pressure region. Numerical simulations showed density, pressure, temperature, and velocity profiles. Simulation results with 20 μm glass microspheres confirmed the location of the initial breakdown and matched experimental shockwave velocities. Nanoparticle size controllability was examined for permalloy and silver by changing the laser fluence, gas

  20. On-Sky Tests of a High-Power Pulsed Laser for Sodium Laser Guide Star Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Otarola, Angel; Hickson, Paul; Gagné, Ronald; Bo, Yong; Zuo, Junwei; Xie, Shiyong; Feng, Lu; Rochester, Simon; Budker, Dmitry; Shen, Shixia; Xue, Suijian; Min, Li; Wei, Kai; Boyer, Corinne; Ellerbroek, Brent; Hu, Jingyao; Peng, Qinjun; Xu, Zuyan

    2016-03-01

    We present results of on-sky tests performed in the summer of 2013 to characterize the performance of a prototype high-power pulsed laser for adaptive optics. The laser operates at a pulse repetition rate (PRR) of 600-800Hz, with a 6% duty cycle. Its coupling efficiency was found to be, in the best test case (using 18W of transmitted power), 231±14 photons s-1 sr-1 atom-1 W-1 m2 when circular polarization was employed and 167±17 photons s-1 sr-1 atom-1 W-1 m2 with linear polarization. No improvement was seen when D2b repumping was used, but this is likely due to the relatively large laser guide star (LGS) diameter, typically 10 arcsec or more, which resulted in low irradiance levels. Strong relaxation oscillations were present in the laser output, which have the effect of reducing the coupling efficiency. To better understand the results, a physical modeling was performed using the measured pulse profiles and parameters specific to these tests. The model results, for a 10 arcsec angular size LGS spot, agree well with the observations. When extrapolating the physical model for a sub-arcsecond angular size LGS (typical of what is needed for a successful astronomical guide star), the model predicts that this laser would have a coupling efficiency of 130 photons s-1 sr-1 atom-1 W-1 m2, using circular polarization and D2b repumping, for a LGS diameter of 0.6 arcsec Full Width at Half Maximum (FWHM), and free of relaxation oscillations in the 589 nm laser light.

  1. Picosecond pulses of variable duration from a high-power passively mode-locked Nd:YVO(4) laser free of spatial hole burning.

    PubMed

    Nadeau, Marie-Christine; Petit, Stéphane; Balcou, Philippe; Czarny, Romain; Montant, Sébastien; Simon-Boisson, Christophe

    2010-05-15

    We report on a high-power passively mode-locked TEM(00)Nd:YVO(4) oscillator, 888 nm diode-pumped, with pulse durations adjustable between 46 ps and 12 ps. The duration tunability was obtained by varying the output coupler (OC) transmission while avoiding resorting to spatial hole burning (SHB) for pulse shortening. At a repetition rate of 91 MHz and for an output power ranging from 15 Wto45 W, we produced SHB-free 12-ps-to32-ps-long pulses. Within this range of power, these are the shortest pulse durations obtained directly from Nd:YVO(4) oscillators.

  2. Pulsed photothermal reflectance measurement of the thermal conductivity of sputtered aluminum nitride thin films

    SciTech Connect

    Zhao Yimin; Zhu Chunlin; Wang Sigen; Tian, J.Z.; Yang, D.J.; Chen, C.K.; Cheng Hao; Hing, Peter

    2004-10-15

    We report on measurements of the thermal conductivity of reactively sputtered aluminum nitride (AlN) thin films with different thickness, ranging from 100 nm to 1 {mu}m, on silicon substrates. The measurements were made at room temperature using the pulsed photothermal reflectance technique. The thermal conductivities of the sample are found to be significantly lower than the single-crystal bulk AlN and increase with an increasing thickness. The thermal resistance at the interface between the AlN film and the silicon substrate is found to be about 7-8x10{sup -8} m{sup 2} K/W.

  3. Physical and electrical properties of induced high-k ZrHfO crystallization with ZrN cap by high power impulse magnetron sputtering for metal-gate metal-insulator-semiconductor structures

    NASA Astrophysics Data System (ADS)

    Tsai, Jung-Ruey; Juan, Pi-Chun; Lin, Cheng-Li; Lin, Guo-Cheng

    2017-01-01

    Metal-gate TiN/ZrN/ZrHfO/p-Si metal-insulator-semiconductor (MIS) structures have been fabricated in this work. The physical and electrical properties were characterized. The crystallization of high-k ZrHfO thin-film is induced by high power impulse magnetron sputtering (HIPIMS) during the deposition of ZrN capping layer. The binding energies and depth profiles were investigated by X-ray photoelectron spectroscopy (XPS). It is found that Zr and Hf out-diffusion from high-k dielectric in samples with HIPIMS is lesser than those in samples with the conventional DC magnetron sputtering (DCMS). The dielectric constant which strongly relates to the tetragonal phase becomes higher and the flatband voltage shift shows smaller by using the HIPIMS method than by the conventional DCMS. The cation and anion vacancies have been investigated by the defect reaction model.

  4. Process-structure-property correlations in pulsed dc reactive magnetron sputtered vanadium oxide thin films

    SciTech Connect

    Venkatasubramanian, Chandrasekaran; Cabarcos, Orlando M.; Drawl, William R.; Allara, David L.; Ashok, S.; Horn, Mark W.; Bharadwaja, S. S. N.

    2011-11-15

    Cathode hysteresis in the reactive pulsed dc sputtering of a vanadium metal target was investigated to correlate the structural and electrical properties of the resultant vanadium oxide thin films within the framework of Berg's model [Berg et al., J. Vac. Sci. Technol. A 5, 202 (1987)]. The process hysteresis during reactive pulsed dc sputtering of a vanadium metal target was monitored by measuring the cathode (target) current under different total gas flow rates and oxygen-to-argon ratios for a power density of {approx}6.6.W/cm{sup 2}. Approximately 20%-25% hysteretic change in the cathode current was noticed between the metallic and oxidized states of the V-metal target. The extent of the hysteresis varied with changes in the mass flow of oxygen as predicted by Berg's model. The corresponding microstructure of the films changed from columnar to equiaxed grain structure with increased oxygen flow rates. Micro-Raman spectroscopy indicates subtle changes in the film structure as a function of processing conditions. The resistivity, temperature coefficient of resistance, and charge transport mechanism, obeying the Meyer-Neldel relation [Meyer and Neldel, Z. Tech. Phys. (Leipzig) 12, 588 (1937)], were correlated with the cathode current hysteric behavior.

  5. High-power CW and long-pulse lasers in the green wavelength regime for copper welding

    NASA Astrophysics Data System (ADS)

    Pricking, Sebastian; Huber, Rudolf; Klausmann, Konrad; Kaiser, Elke; Stolzenburg, Christian; Killi, Alexander

    2016-03-01

    We report on industrial high-power lasers in the green wavelength regime. By means of a thin disk oscillator and a resonator-internal nonlinear crystal for second harmonic generation we are able to extract up to 8 kW pulse power in the few-millisecond range at a wavelength of 515 nm with a duty cycle of 10%. Careful shaping and stabilization of the polarization and spectral properties leads to a high optical-to-optical efficiency larger than 55%. The beam parameter product is designed and measured to be below 5 mm·mrad which allows the transport by a fiber with a 100 μm core diameter. The fiber and beam guidance optics are adapted to the green wavelength, enabling low transmission losses and stable operation. Application tests show that this laser is perfectly suited for copper welding due to the superior absorption of the green wavelength compared to IR, which allows us to produce weld spots with an unprecedented reproducibility in diameter and welding depth. With an optimized set of parameters we could achieve a splatter-free welding process of copper, which is crucial for welding electronic components. Furthermore, the surface condition does not influence the welding process when the green wavelength is used, which allows to skip any expensive preprocessing steps like tin-coating. With minor changes we could operate the laser in cw mode and achieved up to 1.7 kW of cw power at 515 nm with a beam parameter product of 2.5 mm·mrad. These parameters make the laser perfectly suitable for additional applications such as selective laser melting of copper.

  6. High-power, high-brightness pseudospark-produced electron beam driven by improved pulse line accelerator

    SciTech Connect

    Junbino Zhu; Mingchang Wang; Zhijiang Wang

    1995-12-31

    A high power (200KV), intense current density, low emittance (71mmmrad), high brightness (8x10{sup 10}A/m rad) electron beam was generated in the 10cm long, high-voltage-resistive multi-gap hollow cathode pseudospark chamber filled with 15pa nitrogen and driven by an improved pulse line accelerator. The beam was ejected with the 1mm diameter, the 2.2KA beam current, and the 400ns pulse length, and could propagated 20cm in the drift tube. At a distance of 5cm from the anode it penetrated consecutively an acid-sensitive discoloring film and a 0.05mm-thick copper foil both stuck closely, left 0.6mm and 0.3mm holes on them, respectively. That 10 shots on an acid-sensitive film produced a hole of 1.6mm at 7cm downstream of anode showed its good repeatability. After 60 shots the pseudospark discharge chamber was disassembled and observed that almost no destructive damage traces left on the surfaces of its various electrodes and insulators. But on almost all the surfaces of changeable central hole parts installed on intermediate electrodes there are traces of electron emission from the sides facing the anode and of bombardment on the sides facing the cathode, in contrast with which on the front- and back-surfaces of hollow cathode no visible traces of electron emission from then was observed. In addition, there were different tints, strip-like regions on the side of anode facing the cathode. Another interesting phenomenon was that there were a set of concentric circular or elliptical ring pattern on the acid-sensitive discoloring film got at 5cm from the anode and observed tinder a metallograph. It seems that the pseudospark electron beam is Laminar beam i.e, being possessed of a multi-layer structure, at least in the case of multi-gap pseudospark discharge chamber. It was found experimentally that the quality of pseudospark electron beam is much better than that of the cold-cathode electron beam.

  7. Hybrid Er/Yb fibre laser system for generating few-cycle 1.6 to 2.0 {mu}m pulses optically synchronised with high-power pulses near 1 {mu}m

    SciTech Connect

    Andrianov, A V; Anashkina, E A; Murav'ev, S V; Kim, A V

    2013-03-31

    This paper presents the concept of fibre laser system design for generating optically synchronised femtosecond pulses at two, greatly differing wavelengths and reports experimental and numerical simulation studies of nonlinear conversion of femtosecond pulses at 1.5 {mu}m wavelength in a dispersion-shifted fibre, with the generation of synchronised pulses in the ranges 1.6 - 2 and 1 - 1.1 {mu}m. We describe a three-stage high-power fibre amplifier of femtosecond pulses at 1 {mu}m and a hybrid Er/Yb fibre laser system that has enabled the generation of 12 fs pulses with a centre wavelength of 1.7 {mu}m, synchronised with high-power (microjoule level) 250 fs pulses at 1.03 {mu}m. (extreme light fields and their applications)

  8. Niobium sputtered Havar foils for the high-power production of reactive [18F]fluoride by proton irradiation of [18O]H2O targets.

    PubMed

    Wilson, J S; Avila-Rodriguez, M A; Johnson, R R; Zyuzin, A; McQuarrie, S A

    2008-05-01

    Niobium sputtered Havar entrance foils were used for the production of reactive [(18)F]fluoride by proton irradiation of [(18)O]H(2)O targets under pressurized conditions. The synthesis yield in the routine production of 2-[(18)F]fluoro-2-deoxy-glucose (FDG) was used as an indicative parameter of the reactivity of (18)F. The yield of FDG obtained with (18)F produced in a target with Havar foil was used as a baseline. No statistically significant difference was found in the saturated yields of (18)F when using Havar or Havar-Nb sputtered entrance foils. However, the amount of long-lived radionuclidic impurities decreased more than 10-fold using the Havar-Nb entrance foil. The average decay corrected synthesis yield of FDG, evaluated over a period of more than 2 years, was found to be approximately 5% higher when using a Havar-Nb entrance foil and a marked improvement on the FDG yield consistency was noted. In addition, the frequency of target rebuilding was greatly diminished when using the Nb sputtered entrance foil.

  9. Structure and properties of uranium oxide thin films deposited by pulsed dc magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Lin, Jianliang; Dahan, Isaac; Valderrama, Billy; Manuel, Michele V.

    2014-05-01

    Crystalline uranium oxide thin films were deposited in an unbalanced magnetron sputtering system by sputtering from a depleted uranium target in an Ar + O2 mixture using middle frequency pulsed dc magnetron sputtering. The substrate temperature was constantly maintained at 500 °C. Different uranium oxide phases (including UO2-x, UO2, U3O7 and U3O8) were obtained by controlling the percentage of the O2 flow rate to the total gas flow rate (f) in the chamber. The crystal structure of the films was characterized using X-ray diffraction and the microstructure of the films was studied using transmission electron microscopy and atom probe tomography. When the f was below 10%, the film contains a mixture of metallic uranium and UO2-x phases. As the f was controlled in the range of 10-13%, UO2 films with a (2 2 0) preferential orientation were obtained. The oxide phase rapidly changed to a mixture of U3O7 and U3O8 as the f was increased to the range of 15-18%. Further increasing the f to 20% and above, polycrystalline U3O8 thin films with a (0 0 1) preferential orientation were formed. The hardness and Young's modulus of the uranium oxide films were evaluated using nanoindentation. The film containing a single UO2 phase exhibited the maximum hardness of 14.3 GPa and a Young's modulus of 195 GPa. The UO2 thin film also exhibited good thermal stability in that no phase change was observed after annealing at 600 °C in vacuum for 104 h.

  10. Feasibility study on strengthening heating effect of high power short pulse laser on biological tissue by micro/nano metal particles

    NASA Astrophysics Data System (ADS)

    Lv, Yonggang; Huai, Xiulan

    2008-10-01

    A new method for enhancing the heating effect of high power short pulse laser on biological tissue by micro/nano metal particles was proposed. Theoretical analysis of the influences of the micro/nano particle kind, the concentration and the microcosmic distribution of micro/nano particles on the temperature response was carried out with a multi-layer hyperbolic heat conduction model with volumetric heat generation. The results indicate that embedding micro/nano particles could improve the surface temperature increase of biological tissue with short duration and reduce the deeper material temperature under the same heating condition, which would help strengthen the heating effects of high power short pulse laser on biological tissue. This study may open a new technical approach for improving laser applications.

  11. Fabrication of InGaN thin-film transistors using pulsed sputtering deposition

    PubMed Central

    Itoh, Takeki; Kobayashi, Atsushi; Ueno, Kohei; Ohta, Jitsuo; Fujioka, Hiroshi

    2016-01-01

    We report the first demonstration of operational InGaN-based thin-film transistors (TFTs) on glass substrates. The key to our success was coating the glass substrate with a thin amorphous layer of HfO2, which enabled a highly c-axis-oriented growth of InGaN films using pulsed sputtering deposition. The electrical characteristics of the thin films were controlled easily by varying their In content. The optimized InGaN-TFTs exhibited a high on/off ratio of ~108, a field-effect mobility of ~22 cm2 V−1 s−1, and a maximum current density of ~30 mA/mm. These results lay the foundation for developing high-performance electronic devices on glass substrates using group III nitride semiconductors. PMID:27383148

  12. Fabrication of InGaN thin-film transistors using pulsed sputtering deposition

    NASA Astrophysics Data System (ADS)

    Itoh, Takeki; Kobayashi, Atsushi; Ueno, Kohei; Ohta, Jitsuo; Fujioka, Hiroshi

    2016-07-01

    We report the first demonstration of operational InGaN-based thin-film transistors (TFTs) on glass substrates. The key to our success was coating the glass substrate with a thin amorphous layer of HfO2, which enabled a highly c-axis-oriented growth of InGaN films using pulsed sputtering deposition. The electrical characteristics of the thin films were controlled easily by varying their In content. The optimized InGaN-TFTs exhibited a high on/off ratio of ~108, a field-effect mobility of ~22 cm2 V‑1 s‑1, and a maximum current density of ~30 mA/mm. These results lay the foundation for developing high-performance electronic devices on glass substrates using group III nitride semiconductors.

  13. Method and apparatus for generating high power laser pulses in the two to six micron wavelength range

    DOEpatents

    MacPherson, David C.; Nelson, Loren D.; O'Brien, Martin J.

    1996-01-01

    Apparatus performs a method of generating one or more output laser pulses in a range of 2 to 6 microns. When a plurality of the output laser pulses are generated, a first output pulse has any selected wavelength within the range and a second output pulse is temporally closely spaced relative to the first output pulse and has a chosen wavelength differing from the selected wavelength. An oscillator laser cavity is provided with a tunable oscillator rod capable of generating initial laser pulses within a range of from 750 to 1000 nm, and a tuning element is coupled to the rod. A flashlamp is operable to pump the rod. For two pulse operation, the flashlamp has a given duration. A Q-switch provides the initial laser pulses upon operation of the tuning element and the flashlamp. A Raman device coupled to the rod shifts the wavelength of such initial laser pulse into the range of from 2 to 6 microns to form the output laser pulse having a wavelength within the range. For multiple pulses, a controller causes the Q-switch to provide first and second ones of the initial laser pulses, spaced by a time interval less than the given duration. Also, a selector coupled to the tuning element is operable within such duration to successively select the wavelength of the first output pulse and the chosen wavelength of the second initial pulse. The Raman device is responsive to each of the initial light pulses to generate radiation at first and second Stokes wavelengths, each of said the output laser pulses being radiation at the second Stokes wavelength.

  14. Method and apparatus for generating high power laser pulses in the two to six micron wavelength range

    DOEpatents

    MacPherson, D.C.; Nelson, L.D.; O`Brien, M.J.

    1996-12-10

    Apparatus performs a method of generating one or more output laser pulses in a range of 2 to 6 microns. When a plurality of the output laser pulses are generated, a first output pulse has any selected wavelength within the range and a second output pulse is temporally closely spaced relative to the first output pulse and has a chosen wavelength differing from the selected wavelength. An oscillator laser cavity is provided with a tunable oscillator rod capable of generating initial laser pulses within a range of from 750 to 1000 nm, and a tuning element is coupled to the rod. A flashlamp is operable to pump the rod. For two pulse operation, the flashlamp has a given duration. A Q-switch provides the initial laser pulses upon operation of the tuning element and the flashlamp. A Raman device coupled to the rod shifts the wavelength of such initial laser pulse into the range of from 2 to 6 microns to form the output laser pulse having a wavelength within the range. For multiple pulses, a controller causes the Q-switch to provide first and second ones of the initial laser pulses, spaced by a time interval less than the given duration. Also, a selector coupled to the tuning element is operable within such duration to successively select the wavelength of the first output pulse and the chosen wavelength of the second initial pulse. The Raman device is responsive to each of the initial light pulses to generate radiation at first and second Stokes wavelengths, each of said the output laser pulses being radiation at the second Stokes wavelength. 30 figs.

  15. High-Power fiber amplifier with widely tunable repetition rate, fixed pulse duration, and multiple output wavelengths.

    PubMed

    Schrader, Paul E; Farrow, Roger L; Kliner, Dahv A V; Fève, Jean-Philippe; Landru, Nicolas

    2006-11-27

    We report a pulsed, fiber-amplified microchip laser providing widely tunable repetition rate (7.1 - 27 kHz) with constant pulse duration (1.0 ns), pulse energy up to 0.41 mJ, linear output polarization, diffraction-limited beam quality (M(2) < 1.2), and < 1% pulse-energy fluctuations. The pulse duration was shown to minimize nonlinear effects that cause temporal and spectral distortion of the amplified pulses. This source employs passive Q-switching, single-stage single-pass amplification, and cw pumping, thus offering high efficiency, simplicity, and compact, rugged packaging for use in practical applications. The high peak power and high beam quality make this system an ideal pump source for nonlinear frequency conversion, and we demonstrated efficient harmonic generation and optical parametric generation of wavelengths from 213 nm to 4.4 mum with Watt-level output powers.

  16. High-power passively mode-locked Nd:YVO4 oscillator with adjustable pulse duration between 46 ps and 12 ps

    NASA Astrophysics Data System (ADS)

    Nadeau, Marie-Christine; Petit, Stéphane; Balcou, Philippe; Czarny, Romain; Montant, Sébastien; Simon-Boisson, Christophe

    2010-05-01

    We report on a high-power, passively mode-locked, TEM00 Nd:YVO4 oscillator with adjustable pulse duration between 46 and 12ps. The laser is end-pumped by an 888nm laser diode and mode-locking is achieved with a semiconductor saturable absorber mirror (SESAM). The laser has a repetition rate of 91MHz and the M2 beam quality factor is better than 1.2 at 15ps. At the optimum output coupler, it provides a maximum average output power of 45W with 32ps pulse duration. In literature, the presence of spatial hole burning (SHB) often helps to shorten the pulse length down to few picoseconds. However, SHB might be an issue for some specific application requiring e.g. low noise picosecond oscillators. In this contribution, we demonstrate that it is possible to shorten the pulse duration by lowering the intracavity losses without SHB. Pulse tunability from 46 to 12ps is achieved by changing the output coupler of the cavity while staying in the continuous-wave mode-locked regime. Pulse duration is almost linear with the output coupler transmission and increases from 12 to 32ps with average output power ranging from 15 to 45W. In this range of output power, we demonstrate the shortest pulses directly from a Nd:YVO4 oscillator.

  17. Reactive gas pulsing sputtering process, a promising technique to elaborate silicon oxynitride multilayer nanometric antireflective coatings

    NASA Astrophysics Data System (ADS)

    Farhaoui, A.; Bousquet, A.; Smaali, R.; Moreau, A.; Centeno, E.; Cellier, J.; Bernard, C.; Rapegno, R.; Réveret, F.; Tomasella, E.

    2017-01-01

    The oxynitride materials present a high versatility, which enables their properties to be controlled by tuning their elemental composition. This is the case for silicon oxynitrides used for multilayer antireflective coatings (ARCs), where several thin films with various refractive indexes are needed. Different techniques allow for the modification of the thin film composition. In this paper, we investigate the reactive gas pulsing sputtering process to easily tune the thin film composition, from an oxide to a nitride, by controlling the averaged oxygen flow rate, without reducing the deposition rate, compared to a conventional reactive process (CP). We then demonstrated that the refractive indexes of films deposited by this pulsing process (PP) can be varied in the same range compared to films obtained by CP (from 1.83 to 1.45 at 1.95 eV), whereas their extinction coefficients remain low. Finally, the multilayer ARC has been simulated and optimized by a genetic algorithm for wavelength at 600 nm and for the silicon substrate. Various optimized multilayer (mono-, bi- and tri-layers) structures have been deposited by the PP technique and characterized. They are presented in good agreement with the simulated reflectivity. Hence, the PP allows for an easy depositing tri-layer system with a reasonable deposition rate and low reflectivity (8.1% averaged on 400-750 nm visible light range).

  18. Vanadium oxide thin films for bolometric applications deposited by reactive pulsed dc sputtering

    SciTech Connect

    Fieldhouse, N.; Pursel, S. M.; Carey, R.; Horn, M. W.; Bharadwaja, S. S. N.

    2009-07-15

    Vanadium oxide (VO{sub x}) thin films were deposited by reactive pulse dc magnetron sputtering process using a pure vanadium metal target. The structural, microstructure, and electrical properties were correlated as a function of processing parameters such as substrate temperature, Ar:O partial pressures ratios, and pulsed dc power to fabricate these films. The VO{sub x} films deposited at various substrate temperatures between 30 and 300 degree sign C using a range of oxygen to argon partial pressure ratios exhibited huge variation in their microstructure even though most of them are amorphous to x-ray diffraction technique. In addition, the electrical properties such as temperature coefficient of resistance (TCR), resistivity, and noise levels were influenced by film microstructure. The TCRs of the VO{sub x} films were in the range of -1.1% to -2.4% K{sup -1} having resistivity values of 0.1-100 {Omega} cm. In particular, films grown at lower substrate temperatures with higher oxygen partial pressures have shown finer columnar grain structure and exhibited larger TCR and resistivity.

  19. An efficient way to evidence and to measure the metal ion fraction in high power impulse magnetron sputtering (HiPIMS) post-discharge with Pt, Au, Pd and mixed targets

    NASA Astrophysics Data System (ADS)

    Cuynet, S.; Lecas, T.; Caillard, A.; Brault, P.

    2016-12-01

    The proportion of metal ions in a high power impulse magnetron sputtering discharge is key information for the potential development of new materials and new layer architectures deposited by this technique. This paper aims to measure this proportion by using a homemade system consisting of a quartz crystal microbalance and a grid energy analyser assembly. Such a system yields relevant results on the composition of the post-discharge depending on the nature of the gas (Ar, Kr, Xe) and the target materials (Pt, Pd, Au, 50\\text{Au}50$ and 5\\text{Pd}95$ ). In our conditions, the highest proportion of metal ions in the post-discharge are obtained by using Ar gas and reaches 10 %, 12 %, 50 %, 19 % and 88 % for Pt, Au, Pd, 50\\text{Au}50$ and 5\\text{Pd}95$ targets, respectively.

  20. High-power, mid-infrared, picosecond pulses generated by compression of a CO_2 laser beat-wave in GaAs

    NASA Astrophysics Data System (ADS)

    Pigeon, J. J.; Tochitsky, S. Ya.; Joshi, C.

    2015-12-01

    We report on the generation of a train of ~ 2 ps, 10 um laser pulses via multiple four-wave mixing and compression of an infrared laser beat-wave propagating in the negative group velocity dispersion region of bulk GaAs and a combination of GaAs and NaCl. The use of a 200 ps, 106 GHz beat-wave, produced by combining laser pulses amplified on the 10P(20) and 10P(16) transition of a CO2 laser, provides a novel method for generating high-power, picosecond, mid-IR laser pulses at a high repetition rate. By using 165 and 882 GHz beat-waves we show that cascaded phase-mismatched difference frequency generation plays a significant role in the four-wave mixing process in GaAs.

  1. High-power, mid-infrared, picosecond pulses generated by compression of a CO₂ laser beat-wave in GaAs.

    PubMed

    Pigeon, J J; Tochitsky, S Ya; Joshi, C

    2015-12-15

    We report on the generation of a train of ∼2  ps, 10 μm laser pulses via multiple four-wave mixing and compression of an infrared laser beat-wave propagating in the negative group velocity dispersion region of bulk GaAs and a combination of GaAs and NaCl crystals. The use of a 200 ps, 106 GHz beat-wave, produced by combining laser pulses amplified on the 10P(20) and 10P(16) transition of a CO₂ laser, provides a novel method for generating high-power, picosecond, mid-IR laser pulses at a high repetition rate. By using 165 and 882 GHz beat-waves, we show that cascaded phase-mismatched difference frequency generation plays a significant role in the four-wave mixing process in GaAs.

  2. Picosecond to femtosecond pulses from high power self mode-locked ytterbium rod-type fiber laser.

    PubMed

    Deslandes, Pierre; Perrin, Mathias; Saby, Julien; Sangla, Damien; Salin, François; Freysz, Eric

    2013-05-06

    We have designed an ytterbium rod-type fiber laser oscillator with tunable pulse duration. This system that delivers more than 10 W of average power is self mode-locked. It yields femtosecond to picosecond laser pulses at a repetition rate of 74 MHz. The pulse duration is adjusted by changing the spectral width of a band pass filter that is inserted in the laser cavity. Using volume Bragg gratings of 0.9 nm and 0.07 nm spectrum bandwidth, this oscillator delivers nearly Fourier limited 2.8 ps and 18.5 ps pulses, respectively. With a 4 nm interference filter, one obtains picosecond pulses that have been externally dechirped down to 130 fs.

  3. Compact high power mid-infrared optical parametric oscillator pumped by a gain-switched fiber laser with "figure-of-h" pulse shape.

    PubMed

    Jiang, Peipei; Chen, Tao; Wu, Bo; Yang, Dingzhong; Hu, Chengzhi; Wu, Pinghui; Shen, Yonghang

    2015-02-09

    We demonstrate a compact high power mid-infrared (MIR) optical parametric oscillator (OPO) pumped by a gain-switched linearly polarized, pulsed fiber laser. The gain-switched fiber laser was constructed with a piece of Yb doped polarization maintaining (PM) fiber, a pair of fiber Bragg gratings written into the matched passive PM fiber and 6 pigtailed pump laser diodes working at 915 nm with 30 W output peak power each. By modulating the pulse width of the pump laser diode, simple pedestal-free pulse shape or pedestal-free trailing pulse shape ("figure-of-h" as we call it) could be achieved from the gain-switched fiber laser. The laser was employed as the pump of a two-channel, periodically poled magnesium oxide lithium niobate-based OPO system. High power MIR emission was generated with average output power of 5.15 W at 3.8 μm channel and 8.54 W at 3.3 μm channel under the highest pump power of 45 W. The corresponding pump-to-idler conversion efficiency was computed to be 11.7% and 19.1%, respectively. Experimental results verify a significant improvement to signal-to-idler conversion efficiency by using "figure-of-h" pulses over simple pedestal-free pulses. Compared to the master oscillator power amplifier (MOPA) fiber laser counterpart, the presented gain switched fiber laser is more attractive in OPO pumping due to its compactness and simplicity which are beneficial to construction of OPO systems for practical MIR applications.

  4. Shack - Hartmann wavefront sensor for measuring the parameters of high-power pulsed solid-state lasers

    SciTech Connect

    Aleksandrov, A G; Zavalova, V E; Kudryashov, A V; Rukosuev, A L; Sheldakova, Yu V; Samarkin, V V; Romanov, P N

    2010-06-23

    The wavefront of the radiation of two types from high-power solid-state (Ti:sapphire and Nd:glass) lasers is experimentally studied. The measurements are performed using a Shack - Hartmann wavefront sensor. The technical and functional potential of this sensor in measuring laser-based schemes is demonstrated. The results of measuring both static and dynamic wavefront aberrations are discussed. The estimated dynamics of defocus aberration is in agreement with the experimental data. (measurement of laser radiation parameters)

  5. Study of a wide-aperture combined deformable mirror for high-power pulsed phosphate glass lasers

    SciTech Connect

    Samarkin, V V; Aleksandrov, A G; Romanov, P N; Rukosuev, A L; Kudryashov, A V; Jitsuno, T

    2015-12-31

    A deformable mirror with the size of 410 × 468 mm controlled by bimorph piezoceramic plates and multilayer piezo stacks is developed. The response functions of individual actuators and the measurements of the flatness of the deformable mirror surface are presented. The study of mirrors with an interferometer and a wavefront sensor has shown that it is possible to improve the surface flatness down to a residual roughness of 0.033 μm (RMS). The possibility of correction of beam aberrations in an ultra-high-power laser using the created bimorph mirror is demonstrated. (letters)

  6. Effects of the duty ratio on the niobium oxide film deposited by pulsed-DC magnetron sputtering methods.

    PubMed

    Eom, Ji Mi; Oh, Hyun Gon; Cho, Il Hwan; Kwon, Sang Jik; Cho, Eou Sik

    2013-11-01

    Niobium oxide (Nb2O5) films were deposited on p-type Si wafers and sodalime glasses at a room temperature using in-line pulsed-DC magnetron sputtering system with various duty ratios. The different duty ratio was obtained by varying the reverse voltage time of pulsed DC power from 0.5 to 2.0 micros at the fixed frequency of 200 kHz. From the structural and optical characteristics of the sputtered NbOx films, it was possible to obtain more uniform and coherent NbOx films in case of the higher reverse voltage time as a result of the cleaning effect on the Nb2O5 target surface. The electrical characteristics from the metal-insulator-semiconductor (MIS) fabricated with the NbOx films shows the leakage currents are influenced by the reverse voltage time and the Schottky barrier diode characteristics.

  7. High rate reactive magnetron sputter deposition of Al-doped ZnO with unipolar pulsing and impedance control system

    SciTech Connect

    Nishi, Yasutaka; Hirohata, Kento; Tsukamoto, Naoki; Sato, Yasushi; Oka, Nobuto; Shigesato, Yuzo

    2010-07-15

    Al-doped ZnO (AZO) films were deposited on quartz glass substrates, unheated and heated to 200 deg. C, using reactive sputtering with a special feedback system of discharge impedance combined with midfrequency pulsing. A planar Zn-Al alloy target was connected to the switching unit, which was operated in a unipolar pulse mode. The oxidation of the target surface was precisely controlled by a feedback system for the entire O{sub 2} flow ratio including ''the transition region''. The deposition rate was about 10-20 times higher than that for films deposited by conventional sputtering using an oxide target. A deposition rate of AZO films of 390 nm/min with a resistivity of 3.8x10{sup -4} {Omega} cm and a transmittance in the visible region of 85% was obtained when the films were deposited on glass substrates heated to 200 deg. C with a discharge power of 4 kW.

  8. Formation of the active medium in high-power repetitively pulsed gas lasers pumped by an electron-beam-controlled discharge

    NASA Astrophysics Data System (ADS)

    Bulaev, V. D.; Lysenko, S. L.

    2015-07-01

    A high-power repetitively pulsed e-beam-controlled discharge CO2 laser is simulated numerically; the simulation results are compared with experimental data. Optimal sizes and design of electrodes and configuration of the external magnetic field are found, which allow one to introduce no less than 90% electric pump energy into a specified volume of the active medium, including the active volume of a laser with an aperture of 110 × 110 cm. The results obtained can also be used to design other types of highpower gas lasers.

  9. Formation of the active medium in high-power repetitively pulsed gas lasers pumped by an electron-beam-controlled discharge

    SciTech Connect

    Bulaev, V D; Lysenko, S L

    2015-07-31

    A high-power repetitively pulsed e-beam-controlled discharge CO{sub 2} laser is simulated numerically; the simulation results are compared with experimental data. Optimal sizes and design of electrodes and configuration of the external magnetic field are found, which allow one to introduce no less than 90% electric pump energy into a specified volume of the active medium, including the active volume of a laser with an aperture of 110 × 110 cm. The results obtained can also be used to design other types of highpower gas lasers. (lasers)

  10. Design and development of a prototype 25 kV, 10 A long pulse Marx modulator for high power klystron

    NASA Astrophysics Data System (ADS)

    Acharya, Mahesh; Shrivastava, Purushottam

    2016-02-01

    Research, design, and development of high average power modulators for the proposed Indian Spallation Neutron Source are in progress at Raja Ramanna Centre for Advanced Technology. With this objective, a prototype of 25 kV, 10 A, 1 ms Marx modulator at repetition rate of 1 Hz has been designed and developed which serves as a proof of principle and technology assessment stage for further development of high repetition rate high voltage high average power modulators. Insulated Gate Bipolar Transistor (IGBT) based modules of 2.8 kV switching capability have been used as main modules. The modulator had 8.2% droop in output voltage pulse without any droop compensation circuit. A droop compensation involving 15 corrector modules has been used to reduce the droop up to 1%. We have used IGBT based 250 V switches to realize the corrector module. A microcontroller based control unit was designed and developed for triggering the main and corrector modules. With this control unit, programmable output pulse has been achieved. Electrical isolation between high voltage circuits and control circuit has been achieved by the use of fiber optic based control signal transmission. Output pulses of 1 ms pulse width, 800 ns rise time, and 5 μs fall time have been achieved. The modulator has advantages of modular design, adjustable pulse width, adjustable rise time, and fall time.

  11. Design and development of a prototype 25 kV, 10 A long pulse Marx modulator for high power klystron.

    PubMed

    Acharya, Mahesh; Shrivastava, Purushottam

    2016-02-01

    Research, design, and development of high average power modulators for the proposed Indian Spallation Neutron Source are in progress at Raja Ramanna Centre for Advanced Technology. With this objective, a prototype of 25 kV, 10 A, 1 ms Marx modulator at repetition rate of 1 Hz has been designed and developed which serves as a proof of principle and technology assessment stage for further development of high repetition rate high voltage high average power modulators. Insulated Gate Bipolar Transistor (IGBT) based modules of 2.8 kV switching capability have been used as main modules. The modulator had 8.2% droop in output voltage pulse without any droop compensation circuit. A droop compensation involving 15 corrector modules has been used to reduce the droop up to 1%. We have used IGBT based 250 V switches to realize the corrector module. A microcontroller based control unit was designed and developed for triggering the main and corrector modules. With this control unit, programmable output pulse has been achieved. Electrical isolation between high voltage circuits and control circuit has been achieved by the use of fiber optic based control signal transmission. Output pulses of 1 ms pulse width, 800 ns rise time, and 5 μs fall time have been achieved. The modulator has advantages of modular design, adjustable pulse width, adjustable rise time, and fall time.

  12. Tunable GHz pulse repetition rate operation in high-power TEM(00)-mode Nd:YLF lasers at 1047 nm and 1053 nm with self mode locking.

    PubMed

    Huang, Y J; Tzeng, Y S; Tang, C Y; Huang, Y P; Chen, Y F

    2012-07-30

    We report on a high-power diode-pumped self-mode-locked Nd:YLF laser with the pulse repetition rate up to several GHz. A novel tactic is developed to efficiently select the output polarization state for achieving the stable TEM(00)-mode self-mode-locked operations at 1053 nm and 1047 nm, respectively. At an incident pump power of 6.93 W and a pulse repetition rate of 2.717 GHz, output powers as high as 2.15 W and 1.35 W are generated for the σ- and π-polarization, respectively. We experimentally find that decreasing the separation between the gain medium and the input mirror not only brings in the pulse shortening thanks to the enhanced effect of the spatial hole burning, but also effectively introduces the effect of the spectral filtering to lead the Nd:YLF laser to be in a second harmonic mode-locked status. Consequently, pulse durations as short as 8 ps and 8.5 ps are obtained at 1053 nm and 1047 nm with a pulse repetition rate of 5.434 GHz.

  13. Electrical properties of Si-doped GaN prepared using pulsed sputtering

    NASA Astrophysics Data System (ADS)

    Arakawa, Yasuaki; Ueno, Kohei; Imabeppu, Hideyuki; Kobayashi, Atsushi; Ohta, Jitsuo; Fujioka, Hiroshi

    2017-01-01

    In this study, we investigated the basic electrical properties of Si-doped wurtzite GaN films prepared using a low-temperature pulsed sputtering deposition (PSD) process. We found that the electron concentration can be controlled in the range between 1.5 × 1016 and 2.0 × 1020 cm-3. For lightly Si-doped GaN ([Si] = 2.1 × 1016 cm-3), the room temperature (RT) electron mobility was as high as 1008 cm2 V-1 s-1, which was dominantly limited by polar optical phonon scattering. Moreover, we found that heavily Si-doped GaN prepared using PSD exhibited an RT mobility as high as 110 cm2 V-1 s-1 at an electron concentration of 2 × 1020 cm-3, which indicated that the resistivity of this film was almost as small as those of typical transparent conductive oxides such as indium tin oxide. At lower temperatures, the electron mobility increased to 1920 cm2 V-1 s-1 at 136 K, and the temperature dependence was well explained by conventional scattering models. These results indicate that Si-doped GaN prepared using PSD is promising not only for the fabrication of GaN-based power devices but also for use as epitaxial transparent electrode materials for nitride based optical devices.

  14. Optical, structural, and mechanical properties of silicon oxynitride films prepared by pulsed magnetron sputtering.

    PubMed

    Tang, Chien-Jen; Jaing, Cheng-Chung; Tien, Chuen-Lin; Sun, Wei-Chiang; Lin, Shih-Chin

    2017-02-01

    Silicon oxynitride films were deposited by reactive pulsed magnetron sputtering. The optical, structural, and mechanical properties of silicon oxynitride films with different nitrogen proportions were analyzed via spectroscopy, atomic force microscopy, Twyman-Green interferometer, and nanoindentation. The refractive indices of the silicon oxynitride films were adjusted from 1.487 to 1.956 with the increase in nitrogen proportions. The surface roughness decreased from 1.33 to 0.97 nm with the increase in nitrogen proportions. The residual stress of the silicon oxynitride films was higher than for pure silicon nitride and silicon dioxide films. The hardness and Young's modulus increased from 13.51 to 19.74 GPa and 110.41 to 140.49 GPa with the increase in nitrogen proportions, respectively. The hardness and Young's modulus of antireflection coatings using silicon oxynitride film were 13.64 GPa and 102.11 GPa, respectively. Silicon oxynitride film could be used to improve the hardness of antireflective coatings.

  15. Highly phosphorus-doped crystalline Si layers grown by pulse-magnetron sputter deposition

    NASA Astrophysics Data System (ADS)

    Fenske, Frank; Gorka, Benjamin

    2009-04-01

    The electrical properties of highly phosphorus-doped crystalline silicon films deposited by pulse-magnetron sputtering were studied. The films were grown, 450 nm thick, on Si(100) and Si(111) wafers at low substrate temperatures Ts of 450-550 °C and post-treated by rapid thermal annealing (RTA) and plasma hydrogenation (PH). In the case of films grown on Si(100), at all values of Ts postgrowth treatment by RTA resulted in an increase in the dopant activation up to 100% and of the Hall mobility to about bulklike values of 50 cm2 V-1 s-1. This result suggests high structural quality of the films on Si(100). The Si(111) films, which are typically more defective, exhibit a completely different behavior with a strong dependence of the electrical dopant activation and the Hall mobility on Ts. By post-treatment a maximum P donor activation level of 22% could be obtained. The variation in the post-treatment procedure (RTA+PH and PH+RTA) for the films deposited at high Ts showed that PH results only in minor changes in the film properties. The different influence of RTA and PH is discussed in terms of the different defect structure of the films. These investigations reveal that high Ts and after-treatment by RTA are the main preconditions for optimal electrical film properties.

  16. N-polar InGaN-based LEDs fabricated on sapphire via pulsed sputtering

    NASA Astrophysics Data System (ADS)

    Ueno, Kohei; Kishikawa, Eiji; Ohta, Jitsuo; Fujioka, Hiroshi

    2017-02-01

    High-quality N-polar GaN epitaxial films with an atomically flat surface were grown on sapphire (0001) via pulsed sputtering deposition, and their structural and electrical properties were investigated. The crystalline quality of N-polar GaN improves with increasing film thickness and the full width at half maximum values of the x-ray rocking curves for 0002 and 101 ¯ 2 diffraction were 313 and 394 arcsec, respectively, at the film thickness of 6 μ m . Repeatable p-type doping in N-polar GaN films was achieved using Mg dopant, and their hole concentration and mobility can be controlled in the range of 8 × 1016-2 × 1018 cm-3 and 2-9 cm2V-1s-1, respectively. The activation energy of Mg in N-polar GaN based on a temperature-dependent Hall measurement was estimated to be 161 meV, which is comparable to that of the Ga-polar GaN. Based on these results, we demonstrated the fabrication of N-polar InGaN-based light emitting diodes with the long wavelength up to 609 nm.

  17. Saturation of light – current characteristics of high-power lasers (λ = 1.0 – 1.1 mm) in pulsed regime

    SciTech Connect

    Veselov, D A; Kapitonov, V A; Pikhtin, N A; Lyutetskiy, A V; Nikolaev, D N; Slipchenko, S O; Sokolova, Z N; Shamakhov, V V; Shashkin, I S; Tarasov, I S

    2014-11-30

    Semiconductor lasers based on MOVPE-grown asymmetric separate-confinement heterostructures with a broadened waveguide and emitting in the wavelength range 1.0 – 1.1 μm are studied. It is found that the intensity of spontaneous emission from the active region increases with increasing pump current above the lasing threshold and that this is caused by a growth in the concentration of charge carriers in the active region due to the modal gain enhancement needed to compensate for the growing internal optical loss at high pulsed pump currents. It is shown that the increase in the internal optical loss with increasing pulsed pump current is one of the main reasons for saturation of the light – current characteristics of high-power semiconductor lasers. (lasers)

  18. Electrostatic quadrupole plasma mass spectrometer measurements during thin film depositions using simultaneous matrix assisted pulsed laser evaporation and magnetron sputtering

    SciTech Connect

    Hunter, C. N.; Check, M. H.; Muratore, C.; Voevodin, A. A.

    2010-05-15

    A hybrid plasma deposition process, combining matrix assisted pulsed laser evaporation (MAPLE) of carbon nanopearls (CNPs) with magnetron sputtering of gold was investigated for growth of composite films, where 100 nm sized CNPs were encapsulated into a gold matrix. Composition and morphology of such composite films was characterized with x-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy (TEM) analysis. Carbon deposits on a gold magnetron sputter target and carbon impurities in the gold matrices of deposited films were observed while codepositing from gold and frozen toluene-CNP MAPLE targets in pure argon. Electrostatic quadrupole plasma analysis was used to determine that a likely mechanism for generation of carbon impurities was a reaction between toluene vapor generated from the MAPLE target and the argon plasma originating from the magnetron sputtering process. Carbon impurities of codeposited films were significantly reduced by introducing argon-oxygen mixtures into the deposition chamber; reactive oxygen species such as O and O+ effectively removed carbon contamination of gold matrix during the codeposition processes. Increasing the oxygen to argon ratio decreased the magnetron target sputter rate, and hence hybrid process optimization to prevent gold matrix contamination and maintain a high sputter yield is needed. High resolution TEM with energy dispersive spectrometry elemental mapping was used to study carbon distribution throughout the gold matrix as well as embedded CNP clusters. This research has demonstrated that a hybrid MAPLE and magnetron sputtering codeposition process is a viable means for synthesis of composite thin films from premanufactured nanoscale constituents, and that cross-process contaminations can be overcome with understanding of hybrid plasma process interaction mechanisms.

  19. High power mid-infrared supercontinuum generation in a single-mode ZBLAN fiber pumped by amplified picosecond pulses at 2 μm

    NASA Astrophysics Data System (ADS)

    Liu, Kun; Liu, Jiang; Shi, Hongxing; Tan, Fangzhou; Jiang, Yijian; Wang, Pu

    2015-03-01

    We report high power all fiber mid-infrared (mid-IR) supercontinuum (SC) generation in a single-mode ZBLAN (ZrF4- BaF2-LaF3-AlF3-NaF) fiber with up to 21.8 W average output power from 1.9 to beyond 3.8 μm pumped by amplified picosecond pulses from a master oscillator power amplifier (MOPA) based on small-core single-mode thulium-doped fiber (TDF) with injected seed pulse width of 24 ps and repetition of 93.6 MHz at 1963 nm. The optical-optical conversion efficiency from the 793 nm pump laser of the last stage thulium-doped fiber amplifier (TDFA) to mid-IR SC output is 17%. It is, to the best of our knowledge, the highest average power mid-IR SC generation in a ZBLAN fiber to date. In addition, a noise-like fiber oscillator based on a nonlinear loop mirror (NOLM) with wavepacket width of ~1.4 ns and repetition rate of 3.36 MHz at 1966 nm is also used as a seed of the MOPA for mid-IR SC generation in the ZBLAN fiber. At last, a mid-IR SC from 1.9 to beyond 3.6 μm with average output power of 14.3W, which is limited by injected noise-like pulses power, is generated. The optical-optical conversion efficiency from the 793 nm pump laser of the last stage TDFA to mid-IR SC output is 14.9%. This proves the amplified noise-like pulses are also appropriate for high power mid-IR SC generation in the ZBLAN fiber.

  20. Intensity noise reduction of a high-power nonlinear femtosecond fiber amplifier based on spectral-breathing self-similar parabolic pulse evolution

    NASA Astrophysics Data System (ADS)

    Wang, Sijia; Liu, Bowen; Song, Youjian; Hu, Minglie

    2016-04-01

    We report on a simple passive scheme to reduce the intensity noise of high-power nonlinear fiber amplifiers by use of the spectral-breathing parabolic evolution of the pulse amplification with an optimized negative initial chirp. In this way, the influences of amplified spontaneous emission (ASE) on the amplifier intensity noise can be efficiently suppressed, owing to the lower overall pulse chirp, shorter spectral broadening distance, as well as the asymptotic attractive nature of self-similar pulse amplification. Systematic characterizations of the relative intensity noise (RIN) of a free-running nonlinear Yb-doped fiber amplifier are performed over a series of initial pulse parameters. Experiments show that the measured amplifier RIN increases respect to the decreased input pulse energy, due to the increased amount of ASE noise. For pulse amplification with a proper negative initial chirp, the increase of RIN is found to be smaller than with a positive initial chirp, confirming the ASE noise tolerance of the proposed spectral-breathing parabolic amplification scheme. At the maximum output average power of 27W (25-dB amplification gain), the incorporation of an optimum negative initial chirp (-0.84 chirp parameter) leads to a considerable amplifier root-mean-square (rms) RIN reduction of ~20.5% (integrated from 10 Hz to 10 MHz Fourier frequency). The minimum amplifier rms RIN of 0.025% (integrated from 1 kHz to 5 MHz Fourier frequency) is obtained along with the transform-limited compressed pulse duration of 55fs. To our knowledge, the demonstrated intensity noise performance is the lowest RIN level measured from highpower free-running femtosecond fiber amplifiers.

  1. Towards coherent combining of X-band high power microwaves: phase-locked long pulse radiations by a relativistic triaxial klystron amplifier

    PubMed Central

    Ju, Jinchuan; Zhang, Jun; Qi, Zumin; Yang, Jianhua; Shu, Ting; Zhang, Jiande; Zhong, Huihuang

    2016-01-01

    The radio-frequency breakdown due to ultrahigh electric field strength essentially limits power handling capability of an individual high power microwave (HPM) generator, and this issue becomes more challenging for high frequency bands. Coherent power combining therefore provides an alternative approach to achieve an equivalent peak power of the order of ∼100 GW, which consequently provides opportunities to explore microwave related physics at extremes. The triaxial klystron amplifier (TKA) is a promising candidate for coherent power combing in high frequency bands owing to its intrinsic merit of high power capacity, nevertheless phase-locked long pulse radiation from TKA has not yet been obtained experimentally as the coaxial structure of TKA can easily lead to self-excitation of parasitic modes. In this paper, we present investigations into an X-band TKA capable of producing 1.1 GW HPMs with pulse duration of about 103 ns at the frequency of 9.375 GHz in experiment. Furthermore, the shot-to-shot fluctuation standard deviation of the phase shifts between the input and output microwaves is demonstrated to be less than 10°. The reported achievements open up prospects for accomplishing coherent power combining of X-band HPMs in the near future, and might also excite new development interests concerning high frequency TKAs. PMID:27481661

  2. Towards coherent combining of X-band high power microwaves: phase-locked long pulse radiations by a relativistic triaxial klystron amplifier

    NASA Astrophysics Data System (ADS)

    Ju, Jinchuan; Zhang, Jun; Qi, Zumin; Yang, Jianhua; Shu, Ting; Zhang, Jiande; Zhong, Huihuang

    2016-08-01

    The radio-frequency breakdown due to ultrahigh electric field strength essentially limits power handling capability of an individual high power microwave (HPM) generator, and this issue becomes more challenging for high frequency bands. Coherent power combining therefore provides an alternative approach to achieve an equivalent peak power of the order of ∼100 GW, which consequently provides opportunities to explore microwave related physics at extremes. The triaxial klystron amplifier (TKA) is a promising candidate for coherent power combing in high frequency bands owing to its intrinsic merit of high power capacity, nevertheless phase-locked long pulse radiation from TKA has not yet been obtained experimentally as the coaxial structure of TKA can easily lead to self-excitation of parasitic modes. In this paper, we present investigations into an X-band TKA capable of producing 1.1 GW HPMs with pulse duration of about 103 ns at the frequency of 9.375 GHz in experiment. Furthermore, the shot-to-shot fluctuation standard deviation of the phase shifts between the input and output microwaves is demonstrated to be less than 10°. The reported achievements open up prospects for accomplishing coherent power combining of X-band HPMs in the near future, and might also excite new development interests concerning high frequency TKAs.

  3. Computational and experimental progress on laser-activated gas avalanche switches for broadband, high-power electromagnetic pulse generation

    SciTech Connect

    Mayhall, D.J.; Yee, J.H. ); Villa, F. )

    1990-09-01

    The gas avalanche switch, a high-voltage, picosecond-speed switch, has been proposed. The basic switch consists of pulse-charged electrodes, immersed in a high-pressure (7--800 atm) gas. An avalanche discharge is induced in the gas between the electrodes by ionization from a picosecond-scale laser pulse. The avalanching electrons move toward the anode, causing the applied voltage to collapse in picoseconds. This voltage collapse, if rapid enough, generates electromagnetic waves. A two-dimensional (2D), finite difference computer code solves Maxwell's equations for transverse magnetic modes for rectilinear electrodes between parallel plate conductors, along with electron conservation equations for continuity, momentum, and energy. Collision frequencies for ionization and momentum and energy transfer to neutral molecules are assumed to scale linearly with neutral pressure. Electrode charging and laser-driven electron deposition are assumed to be instantaneous. Code calculations are done for a pulse generator geometry, consisting of an 0.7 mm wide by 0.8 mm high, beveled, rectangular center electrode between grounded parallel plates at 2 mm spacing in air. 17 refs., 12 figs., 2 tabs.

  4. Numerical simulation of high-power virtual-cathode reflex triode driven by repetitive short pulse electron gun

    SciTech Connect

    Yovchev, I.G.; Spassovsky, I.P.; Nikolov, N.A.; Dimitrov, D.P.; Messina, G.; Raimondi, P.; Barroso, J.J.; Correa, R.A.

    1996-06-01

    A virtual-cathode reflex triode is investigated by numerical simulations. A trapezoidal in shape voltage pulse with an amplitude of 300 kV is applied to the solid cathode of the device to drive the cathode negative. The electron beam-to-microwave power conversion efficiency {epsilon}, calculated for the pulse flat top with a duration {tau}{sub ft} = 1.2 ns is approximately the same (about 1.5--2%) as well as for a long flat top ({tau}{sub ft} = 4 ns). The simulations show a 10--15% increase of {epsilon} at {tau}{sub ft} shortening to 0.6 ns. However, this occurs when the anode mesh transparency is high (80--90%). Considerable enhancement of the efficiency (about four times) for {tau}{sub ft} = 0.6 ns has been calculated if the cathode side surface is brought near to the anode tube (from {approx}0.5% at cathode radius R{sub c} = 1.6 cm to {approx}2% at R{sub c} = 3.8 cm). The obtained results would find an application for the design of virtual-cathode reflex triode devices driven by a short pulse and high repetition rate electron gun.

  5. Time-resolved electron thermal conduction by probing of plasma formation in transparent solids with high power subpicosecond laser pulses

    SciTech Connect

    Vu, B.T.V.

    1994-02-01

    This dissertation work includes a series of experimental measurements in a search for better understanding of high temperature (10{sup 4}-10{sup 6}K) and high density plasmas (10{sup 22}-10{sup 24}cm{sup {minus}3}) produced by irradiating a transparent solid target with high intensity (10{sup 13} - 10{sup 15}W/cm{sup 2}) and subpicosecond (10{sup {minus}12}-10{sup {minus}13}s) laser pulses. Experimentally, pump and probe schemes with both frontside (vacuum-plasma side) and backside (plasma-bulk material side) probes are used to excite and interrogate or probe the plasma evolution, thereby providing useful insights into the plasma formation mechanisms. A series of different experiments has been carried out so as to characterize plasma parameters and the importance of various nonlinear processes. Experimental evidence shows that electron thermal conduction is supersonic in a time scale of the first picosecond after laser irradiation, so fast that it was often left unresolved in the past. The experimental results from frontside probing demonstrate that upon irradiation with a strong (pump) laser pulse, a thin high temperature ({approximately}40eV) super-critical density ({approximately}10{sup 23}/cm{sup 3}) plasma layer is quickly formed at the target surface which in turn becomes strongly reflective and prevents further transmission of the remainder of the laser pulse. In the bulk region behind the surface, it is also found that a large sub-critical ({approximately}10{sup 18}/cm{sup 3}) plasma is produced by inverse Bremsstrahlung absorption and collisional ionization. The bulk underdense plasma is evidenced by large absorption of the backside probe light. A simple and analytical model, modified from the avalanche model, for plasma evolution in transparent materials is proposed to explain the experimental results. Elimination of the bulk plasma is then experimentally illustrated by using targets overcoated with highly absorptive films.

  6. Deposition and characterization of titania-silica optical multilayers by asymmetric bipolar pulsed dc sputtering of oxide targets

    NASA Astrophysics Data System (ADS)

    Sagdeo, P. R.; Shinde, D. D.; Misal, J. S.; Kamble, N. M.; Tokas, R. B.; Biswas, A.; Poswal, A. K.; Thakur, S.; Bhattacharyya, D.; Sahoo, N. K.; Sabharwal, S. C.

    2010-02-01

    Titania-silica (TiO2/SiO2) optical multilayer structures have been conventionally deposited by reactive sputtering of metallic targets. In order to overcome the problems of arcing, target poisoning and low deposition rates encountered there, the application of oxide targets was investigated in this work with asymmetric bipolar pulsed dc magnetron sputtering. In order to evaluate the usefulness of this deposition methodology, an electric field optimized Fabry Perot mirror for He-Cd laser (λ = 441.6 nm) spectroscopy was deposited and characterized. For comparison, this mirror was also deposited by the reactive electron beam (EB) evaporation technique. The mirrors developed by the two complementary techniques were investigated for their microstructural and optical reflection properties invoking atomic force microscopy, ellipsometry, grazing incidence reflectometry and spectrophotometry. From these measurements the layer geometry, optical constants, mass density, topography, surface and interface roughness and disorder parameters were evaluated. The microstructural properties and spectral functional characteristics of the pulsed dc sputtered multilayer mirror were found to be distinctively superior to the EB deposited mirror. The knowledge gathered during this study has been utilized to develop a 21-layer high-pass edge filter for radio photoluminescence dosimetry.

  7. INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Behavior of gain-guided lasers generating high-power nanosecond pulses

    NASA Astrophysics Data System (ADS)

    Erbert, G.

    1988-11-01

    Computer-controlled apparatus was used in an investigation of gain-guided narrow-stripe AlGaAs double heterostructure lasers. These lasers were excited with current pulses of 10 ns duration and amplitudes up to 3 A. The watt-ampere characteristics together with near- and far-field radiation patterns were considered using an analytic model of the lasers. The results showed that the values of the gain under a stripe contact or of the absorption outside this region varied with the output power.

  8. High-power efficient cw and pulsed lasers based on bulk Yb : KYW crystals with end diode pumping

    SciTech Connect

    Kim, G H; Yang, G H; Lee, D S; Kulik, Alexander V; Sall', E G; Chizhov, S A; Yashin, V E; Kang, U

    2012-04-30

    End-diode-pumped lasers based on one and two Yb : KYW crystals operating in cw and Q-switched regimes, as well as in the regime of mode-locking, are studied. The single-crystal laser generated stable ultrashort (shorter than 100 fs) laser pulses at wavelengths of 1035 and 1043 nm with an average power exceeding 1 W. The average output power of the two-crystal laser exceeded 18 W in the cw regime and 16 W in the Q-switched regime with a slope efficiency exceeding 30%.

  9. High-power 850-870-nm pulsed lasers based on heterostructures with narrow and wide waveguides

    SciTech Connect

    Ladugin, M A; Koval', Yu P; Marmalyuk, Aleksandr A; Petrovskii, V A; Bagaev, T A; Andreev, A Yu; Padalitsa, A A; Simakov, V A

    2013-05-31

    The power and spectral characteristics of pulsed laser diode arrays operating in the spectral range of 850-870 nm and based on heterostructures of two different types (with narrow and wide waveguides) are studied. It is found that the power-current characteristics of the laser arrays of both types are linear within the pump current range of 10-50 A and that the steepness of these characteristics decreases at currents exceeding 80 A. The decrease in the slope efficiency is more noticeable for laser arrays based on heterostructures with wide waveguides. (semiconductor lasers. physics and technology)

  10. Adaptive-feedback spectral-phase control for interactions with transform-limited ultrashort high-power laser pulses.

    PubMed

    Liu, Cheng; Zhang, Jun; Chen, Shouyuan; Golovin, Gregory; Banerjee, Sudeep; Zhao, Baozhen; Powers, Nathan; Ghebregziabher, Isaac; Umstadter, Donald

    2014-01-01

    Fourier-transform-limited light pulses were obtained at the laser-plasma interaction point of a 100-TW peak-power laser in vacuum. The spectral-phase distortion induced by the dispersion mismatching between the stretcher, compressor, and dispersive materials was fully compensated for by means of an adaptive closed-loop. The coherent temporal contrast on the sub-picosecond time scale was two orders of magnitude higher than that without adaptive control. This novel phase control capability enabled the experimental study of the dependence of laser wakefield acceleration on the spectral phase of intense laser light.

  11. Investigation of high power, pulsed, neodymium-YAG lasers for correcting opacities of the human eye. Master's thesis

    SciTech Connect

    Riggins, J.

    1982-06-01

    This paper will investigate the use of high peak power, nanosecond laser pulses focused in the posterior chamber of the eye to rupture opacified posterior lens capsule tissue or vitreous strands through the creation of a spark plasma and associated shock wave. The author discusses current theories on the formation of the shock wave and its relation to laser beam parameters along with laboratory experiments designed to create and study shock waves and their effects in pig and human eyes. The experimental procedure will utilize a Q-switched Nd-YAG laser interfaced with an ophthalmic slitlamp to simulate the actual conditions under which the physician would perform the operation.

  12. High-Power UV Lasers: Tunable Ultraviolet Burst-Mode Laser System Produces High-Energy Pulses

    DTIC Science & Technology

    2008-08-01

    typically Nd:YAG) that is “sliced” into a burst train using either a pair of electro- optic Pockels cells or an acousto - optic deflector . 1-5 In one exception...JOSEPH D . MILLER, TERRENCE R. MEYER, AND JAMES R. GORD While planar laser-induced-fluorescence (PLIF) imaging of aerodynamic and combustion flows...pumped optical - parametric-oscillator (OPO) systems operated in what has come to be known as “pulse-burst” mode. In combination with sum-frequency

  13. Seismoacoustic responses to high-power electric pulses from well logging data at the Bishkek geodynamical test area

    NASA Astrophysics Data System (ADS)

    Zakupin, A. S.; Bogomolov, L. M.; Mubassarova, V. A.; Il'ichev, P. V.

    2014-09-01

    The results of recording seismoacoustic emission (SAE) in the boreholes of the Bishkek geodynamical test area in Tien Shan, Kyrgyzstan, are presented. The spectral structure of SAE signals and the pattern of variations in SAE intensity during electromagnetic (EM) sounding of the Earth's crust by the highpower ERGU-600-2 generator unit are studied. The statistical methods for SAE data processing are adjusted for the problem of revealing the correlations between SAE responses and pulsed electrical impacts (i.e., energy input into the medium). The response of the medium to EM soundings, which are conducted for monitoring the apparent resistivity of the rocks, is revealed. The response of the medium manifests itself as the increase in SAE intensity (the responses to the electric current pulses generated during the soundings). The SAE responses belong to the same group of the effects (the signs of external forcing of rock destruction) as the variations in seismicity during the runs of the geophysical magneto-hydrodynamic (MHD) generators in 1983-1989 or experimental soundings in 2000-2005. The sources of SAE signals are located at shallow depths, near the geophone installation place. This accounts for the difference between the variations in SAE intensity and microseismicity in response to the same impact.

  14. High-power sources with smoothly adjustable pulse duration for powering gas-discharge tubes of laser pumping systems

    NASA Astrophysics Data System (ADS)

    Vakulenko, V. M.; Ivanov, L. P.; Ganshin, Y. A.; Karpyshev, I. L.; Korneyev, V. A.

    1985-10-01

    A series of power supplies for gas-discharge tubes in laser pumping systems has been developed on the basis of the same circuit but with different levels of partial discharge of the capacitive energy storing device. The charger converts the a.c. network voltage into a constant current, very efficiently and at the same charging rate regardless of the discharge level. An overall size and weight reduction is made possible by an intermediate frequency conversion from 50 Hz to 1 kHz, which also allows raising the repetition rate of output pulses. The charger consists of an inverter and a rectifier. The parallel-type inverter includes a thyristor-diode bridge with capacitors and a transformer, and a choke coil, for converting the sine-wave a.c. network voltage into a higher-frequency (1 kHz) square-wave alternating one after the first rectifying it. An important feature here is stiff overvoltage suppression, especially across the switching capacitors, during wide swings such as from no load to full load. The rectifier includes a 300/1000 V step-up transformer with another thyristor-diode bridge and a choke coil in series. A discharge commutator across the rectifier output shunted by a filter-capacitance ensures proper cutoff of the charge discharge current and corresponding control of the pulse duration.

  15. TiN films fabricated by reactive gas pulse sputtering: A hybrid design of multilayered and compositionally graded structures

    NASA Astrophysics Data System (ADS)

    Yang, Jijun; Zhang, Feifei; Wan, Qiang; Lu, Chenyang; Peng, Mingjing; Liao, Jiali; Yang, Yuanyou; Wang, Lumin; Liu, Ning

    2016-12-01

    Reactive gas pulse (RGP) sputtering approach was used to prepare TiN thin films through periodically changing the N2/Ar gas flow ratio. The obtained RGPsbnd TiN film possessed a hybrid architecture containing compositionally graded and multilayered structures, composed of hcp Ti-phase and fcc TiN-phase sublayers. Meanwhile, the RGP-TiN film exhibited a composition-oscillation along the film thickness direction, where the Ti-phase sublayer had a compositional gradient and the TiN-phase retained a constant stoichiometric ratio of Ti:N ≈ 1. The film modulation ratio λ (the thicknesses ratio of the Ti and TiN-phase sublayer) can be effectively tuned by controlling the undulation behavior of the N2 partial flow rate. Detailed analysis showed that this hybrid structure originated from a periodic transition of the film growth mode during the reactive sputtering process.

  16. Optimal design of semiconductor opening switches for use in the inductive stage of high power pulse generators

    NASA Astrophysics Data System (ADS)

    Engelko, A.; Bluhm, H.

    2004-05-01

    Semiconductor opening switches (SOS) are able to interrupt currents at density levels of up to 10 kA/cm2 in less than 10 ns, operate at repetition rates up to 1 kHz, and possess lifetimes of more than 1011 pulses. If stacked, SOS diodes can hold off voltage levels up to several 100 kV. They are therefore ideal for the design of compact high voltage pulse generators of the GW-class for industrial applications. The aim of this work was to improve our understanding of the opening process in a semiconductor diode of SOS-type with a doping profile of p+pnn+ structure, obtainable through diffusion from the surfaces. To simulate the physical processes inside this diode the code POSEOSS was developed. It contains a detailed physical model of charge carrier transport under the influence of density gradients and electric fields and considers all relevant generation and recombination processes. It possesses a large degree of flexibility and is easy to use, and thus allows to carry out parameter studies to determine the influence of different physical quantities, such as doping and impurity levels, on the performance of the device. When applying the code some interesting results concerning the plasma dynamics during the opening process in the switch have been found. In particular, using realistic values for the charge carrier mobility, it was found that the opening process starts first at the n-n+ boundary. Also it has been possible to derive the physical conditions for the occurrence of the SOS-effect. Based on the simulation results a simplified SOS equivalent circuit model has been developed. This model can be used in the circuit simulation program PSPICE. A pulse generator scheme based on inductive storage is proposed, in which power multiplication is achieved by unloading the inductors, previously charged in series, in parallel. This scheme can be considered as the inductive equivalent of a Marx-generator. PSPICE simulations of such a scheme based on semiconductor opening

  17. Trepanning drilling of stainless steel using a high-power Ytterbium-doped fiber ultrafast laser: influence of pulse duration on hole geometry and processing quality

    NASA Astrophysics Data System (ADS)

    Lopez, John; Dijoux, Mathieu; Devillard, Raphael; Faucon, Marc; Kling, Rainer

    2014-03-01

    Percussion drilling is a well-established technique for several applicative markets such as for aircraft and watch industries. Lamp pumped solid state lasers and more recently fiber lasers, operating in millisecond or nanosecond regimes, are classically used for these applications. However, due to their long pulse duration, these technologies are not suitable for emerging applicative market such as fuel injectors for automotive industry. Only the ultrashort laser technology, combined with special drilling optics like trepanning head, has the potential to fulfill the needs for this new market in terms of processing quality, custom-shape capabilities and short drilling time. Although numerous papers dealing with percussion drilling have been reported in the literature, only few papers are dedicated to trepanning drilling. In this context, we present some results on the influence of pulse duration on gas-assisted laser drilling of stainless steel using a trepanning head and a high power Ytterbium doped fiber ultrafast laser (20W). The influence of pulse energy (7- 64μJ), fluence (3-25 J/cm2), drilling time (1-20s), processing gas pressure and drilling strategy will be discussed as well.

  18. Influence of High-Power Pulsed IR Laser Radiation on the Electrophysical Properties of Cd x Hg1- x Те Heteroepitaxial Layers

    NASA Astrophysics Data System (ADS)

    Talipov, N. Kh.

    2013-05-01

    Results of investigations into the electrophysical properties of p- and n-type Cd x Hg1- x Te heteroepitaxial layers grown by molecular beam and liquid phase epitaxy methods after exposure to high-power pulsed IR radiation of solid-state Nd3+:YAG and chemical DF lasers at wavelengths of 1.06 and 3.8-4.2 μm, respectively, are presented. It is demonstrated that the main types of defects resulting from pulsed irradiation are mercury vacancies that play the role of acceptors in this material. The spatial distribution of generated mercury vacancies depends on the intensity and wavelength of laser radiation: the defects generated by pulses of the Nd3+:YAG laser are concentrated only near the surface, whereas DF-laser radiation creates defects in the entire volume of the heteroepitaxial structures. It is established that irradiation with the Nd3+:YAG laser of the p-Cd x Hg1- x Te heteroepitaxial layers implanted by boron ions leads to the activation of implanted boron atoms as a result of melting and recrystallization of the irradiated surface layer.

  19. High-power supercontinuum generation using high-repetition-rate ultrashort-pulse fiber laser for ultrahigh-resolution optical coherence tomography in 1600 nm spectral band

    NASA Astrophysics Data System (ADS)

    Yamanaka, Masahito; Kawagoe, Hiroyuki; Nishizawa, Norihiko

    2016-02-01

    We describe the generation of a high-power, spectrally smooth supercontinuum (SC) in the 1600 nm spectral band for ultrahigh-resolution optical coherence tomography (UHR-OCT). A clean SC was achieved by using a highly nonlinear fiber with normal dispersion properties and a high-quality pedestal-free pulse obtained from a passively mode-locked erbium-doped fiber laser operating at 182 MHz. The center wavelength and spectral width were 1578 and 172 nm, respectively. The output power of the SC was 51 mW. Using the developed SC source, we demonstrated UHR-OCT imaging of biological samples with a sensitivity of 109 dB and an axial resolution of 4.9 µm in tissue.

  20. Pulsed high-power AlGaN-cladding-free blue laser diodes on semipolar (202xAF1xAF) GaN substrates

    NASA Astrophysics Data System (ADS)

    Pourhashemi, A.; Farrell, R. M.; Hardy, M. T.; Hsu, P. S.; Kelchner, K. M.; Speck, J. S.; DenBaars, S. P.; Nakamura, S.

    2013-10-01

    We demonstrate high-power AlGaN-cladding-free blue laser diodes (LDs) on semipolar (202¯1¯) GaN substrates with peak output powers and external quantum efficiencies (EQEs) that are comparable to state-of-the-art commercial c-plane devices. Ridge waveguide LDs were fabricated on (202¯1¯) GaN substrates using InGaN waveguiding layers and GaN cladding layers. The devices lased at 454 nm at room temperature. We measured an output power of 2.15 W, an EQE of 39%, and a differential quantum efficiency of 49% from a single facet with a pulsed drive current (current density) of 2.02 A (28.1 kA/cm2).

  1. High-power Stirling-type pulse tube cryocooler: Observation and reduction of regenerator temperature-inhomogeneities

    NASA Astrophysics Data System (ADS)

    Dietrich, M.; Yang, L. W.; Thummes, G.

    2007-05-01

    A single stage Stirling-type pulse tube cryocooler driven by a 10 kW-class linear compressor was built and tested. During operation an azimuthal temperature inhomogeneity around the circumference of the regenerator was observed indicating a significant parasitic streaming in the regenerator. The nature of this streaming was examined and a numerical model based on the Sage software was created to understand its origin. It turns out that there is a critical operating condition where a self-preserving streaming starts to circulate in the regenerator. This critical condition is found to depend on the temperature gradient in the regenerator, the amount of mass flow and on the transverse thermal conductivity of the regenerator material. To overcome the negative effect of circulating streaming, the transverse heat conductance in the regenerator was increased by use of sandwich type fillings, where a part of the original stainless screens was replaced by materials with higher thermal conductance. Using these type regenerator fillings, the losses from streaming were significantly reduced and the refrigeration temperature was lowered to 34.5 K. Cooling powers of 50 W at 45 K and 200 W at 70 K are available with electric input powers of 6.3 kW and 8.6 kW, respectively.

  2. A novel sputtering technique: Inductively Coupled Impulse Sputtering (ICIS)

    NASA Astrophysics Data System (ADS)

    Loch, D. A. L.; Ehiasarian, A. P.

    2012-09-01

    Sputtering magnetic materials with magnetron based systems has the disadvantage of field quenching and variation of alloy composition with target erosion. The advantage of eliminating magnetic fields in the chamber is that this enables sputtered particles to move along the electric field more uniformly. Inductively coupled impulse sputtering (ICIS) is a form of high power impulse magnetron sputtering (HIPIMS) without a magnetic field where a high density plasma is produced by a high power radio frequency (RF) coil in order to sputter the target and ionise the metal vapour. In this emerging technology, the effects of power and pressure on the ionisation and deposition process are not known. The setup comprises of a 13.56 MHz pulsed RF coil pulsed with a duty cycle of 25 %. A pulsed DC voltage of 1900 V was applied to the cathode to attract Argon ions and initiate sputtering. Optical emission spectra (OES) for Cu and Ti neutrals and ions at constant pressure show a linear intensity increase for peak RF powers of 500 W - 3400 W and a steep drop of intensity for a power of 4500 W. Argon neutrals show a linear increase for powers of 500 W - 2300 W and a saturation of intensity between 2300 W - 4500 W. The influence of pressure on the process was studied at a constant peak RF power of 2300 W. With increasing pressure the ionisation degree increased. The microstructure of the coatings shows globular growth at 2.95×10-2 mbar and large-grain columnar growth at 1.2×10-1 mbar. Bottom coverage of unbiased vias with a width of 0.360 μm and aspect ratio of 2.5:1 increased from 15 % to 20 % for this pressure range. The current work has shown that the concept of combining a RF powered coil with a magnet-free high voltage pulsed DC powered cathode is feasible and produces very stable plasma. The experiments have shown a significant influence of power and pressure on the plasma and coating microstructure.

  3. InN thin-film transistors fabricated on polymer sheets using pulsed sputtering deposition at room temperature

    NASA Astrophysics Data System (ADS)

    Lye, Khe Shin; Kobayashi, Atsushi; Ueno, Kohei; Ohta, Jitsuo; Fujioka, Hiroshi

    2016-07-01

    Indium nitride (InN) is potentially suitable for the fabrication of high performance thin-film transistors (TFTs) because of its high electron mobility and peak electron velocity. However, InN is usually grown using a high temperature growth process, which is incompatible with large-area and lightweight TFT substrates. In this study, we report on the room temperature growth of InN films on flexible polyimide sheets using pulsed sputtering deposition. In addition, we report on the fabrication of InN-based TFTs on flexible polyimide sheets and the operation of these devices.

  4. Fabrication of full-color InGaN-based light-emitting diodes on amorphous substrates by pulsed sputtering.

    PubMed

    Shon, Jeong Woo; Ohta, Jitsuo; Ueno, Kohei; Kobayashi, Atsushi; Fujioka, Hiroshi

    2014-06-23

    InGaN-based light-emitting diodes (LEDs) have been widely accepted as highly efficient light sources capable of replacing incandescent bulbs. However, applications of InGaN LEDs are limited to small devices because their fabrication process involves expensive epitaxial growth of InGaN by metalorganic vapor phase epitaxy on single-crystal wafers. If we can utilize a low-cost epitaxial growth process, such as sputtering on large-area substrates, we can fabricate large-area InGaN light-emitting displays. Here, we report the growth of GaN (0001) and InGaN (0001) films on amorphous SiO2 by pulsed sputtering deposition. We found that using multilayer graphene buffer layers allows the growth of highly c-axis-oriented GaN films even on amorphous substrates. We fabricated red, green, and blue InGaN LEDs and confirmed their successful operation. This successful fabrication of full-color InGaN LEDs on amorphous substrates by sputtering indicates that the technique is quite promising for future large-area light-emitting displays on amorphous substrates.

  5. Generation of Shear Alfvén Waves by Repetitive High Power Microwave Pulses Near the Electron Plasma Frequency - A laboratory study of a ``Virtual Antenna''

    NASA Astrophysics Data System (ADS)

    Wang, Yuhou; Gekelman, Walter; Pribyl, Patrick; van Compernolle, Bart; Papadopoulos, Konstantinos

    2015-11-01

    ELF / ULF waves are important in terrestrial radio communications but difficult to launch using ground-based structures due to their enormous wavelengths. In spite of this generation of such waves by field-aligned ionospheric heating modulation was first demonstrated using the HAARP facility. In the future heaters near the equator will be constructed and laboratory experiments on cross-field wave propagation could be key to the program's success. Here we report a detailed laboratory study conducted on the Large Plasma Device (LaPD) at UCLA. In this experiment, ten rapid pulses of high power microwaves (250 kW X-band) near the plasma frequency were launched transverse to the background field, and were modulated at a variable fraction (0.1-1.0) of fci. Along with bulk electron heating and density modification, the microwave pulses generated a population of fast electrons. The field-aligned current carried by the fast electrons acted as an antenna that radiated shear Alfvén waves. It was demonstrated that a controllable arbitrary frequency (f

  6. In-situ structural integrity evaluation for high-power pulsed spallation neutron source - Effects of cavitation damage on structural vibration

    NASA Astrophysics Data System (ADS)

    Wan, Tao; Naoe, Takashi; Futakawa, Masatoshi

    2016-01-01

    A double-wall structure mercury target will be installed at the high-power pulsed spallation neutron source in the Japan Proton Accelerator Research Complex (J-PARC). Cavitation damage on the inner wall is an important factor governing the lifetime of the target-vessel. To monitor the structural integrity of the target vessel, displacement velocity at a point on the outer surface of the target vessel is measured using a laser Doppler vibrometer (LDV). The measured signals can be used for evaluating the damage inside the target vessel because of cyclic loading and cavitation bubble collapse caused by pulsed-beam induced pressure waves. The wavelet differential analysis (WDA) was applied to reveal the effects of the damage on vibrational cycling. To reduce the effects of noise superimposed on the vibration signals on the WDA results, analysis of variance (ANOVA) and analysis of covariance (ANCOVA), statistical methods were applied. Results from laboratory experiments, numerical simulation results with random noise added, and target vessel field data were analyzed by the WDA and the statistical methods. The analyses demonstrated that the established in-situ diagnostic technique can be used to effectively evaluate the structural response of the target vessel.

  7. High power neutron production targets

    SciTech Connect

    Wender, S.

    1996-06-01

    The author describes issues of concern in the design of targets and associated systems for high power neutron production facilities. The facilities include uses for neutron scattering, accelerator driven transmutation, accelerator production of tritium, short pulse spallation sources, and long pulse spallation sources. Each of these applications requires a source with different design needs and consequently different implementation in practise.

  8. Comparative effects of extremely high power microwave pulses and a brief CW irradiation on pacemaker function in isolated frog heart slices.

    PubMed

    Pakhomov, A G; Mathur, S P; Doyle, J; Stuck, B E; Kiel, J L; Murphy, M R

    2000-05-01

    The existence of specific bioeffects due to high peak power microwaves and their potential health hazards are among the most debated but least explored problems in microwave biology. The present study attempted to reveal such effects by comparing the bioeffects of short trains of extremely high power microwave pulses (EHPP, 1 micros width, 250-350 kW/g, 9.2 GHz) with those of relatively low power pulses (LPP, 0.5-10 s width, 3-30 W/g, 9.2 GHz). EHPP train duration and average power were made equal to those of an LPP; therefore both exposure modalities produced the same temperature rise. Bioeffects were studied in isolated, spontaneously beating slices of the frog heart. In most cases, a single EHPP train or LPP immediately decreased the inter-beat interval (IBI). The effect was proportional to microwave heating, fully reversible, and easily reproducible. The magnitude and time course of EHPP- and LPP-induced changes always were the same. No delayed or irreversible effects of irradiation were observed. The same effect could be repeated in a single preparation numerous times with no signs of adaptation, sensitization, lasting functional alteration, or damage. A qualitatively different effect, namely, a temporary arrest of preparation beats, could be observed when microwave heating exceeded physiologically tolerable limits. This effect also did not depend on whether the critical temperature rise was produced by LPP or EHPP exposure. Within the studied limits, we found no indications of EHPP-specific bioeffects. EHPP- and LPP-induced changes in the pacemaker rhythm of isolated frog heart preparation were identical and could be entirely attributed to microwave heating.

  9. The Influence of High-Power Ion Beams and High-Intensity Short-Pulse Implantation of Ions on the Properties of Ceramic Silicon Carbide

    NASA Astrophysics Data System (ADS)

    Kabyshev, A. V.; Konusov, F. V.; Pavlov, S. K.; Remnev, G. E.

    2016-02-01

    The paper is focused on the study of the structural, electrical and optical characteristics of the ceramic silicon carbide before and after irradiation in the regimes of the high-power ion beams (HPIB) and high-intensity short-pulse implantation (HISPI) of carbon ions. The dominant mechanism of transport of charge carriers, their type and the energy spectrum of localized states (LS) of defects determining the properties of SiC were established. Electrical and optical characteristics of ceramic before and after irradiation are determined by the biographical and radiation defects whose band gap (BG) energy levels have a continuous energetic distribution. A dominant p-type activation component of conduction with participation of shallow acceptor levels 0.05-0.16 eV is complemented by hopping mechanism of conduction involving the defects LS with a density of 1.2T017-2.4T018 eV-Am-3 distributed near the Fermi level.The effect of radiation defects with deep levels in the BG on properties change dominates after HISPI. A new material with the changed electronic structure and properties is formed in the near surface layer of SiC after the impact of the HPIB.

  10. An innovative high-power constant-current pulsed-arc power-supply for a high-density pulsed-arc-plasma ion-source using a LaB6-filament.

    PubMed

    Ueno, A; Oguri, H; Ikegami, K; Namekawa, Y; Ohkoshi, K; Tokuchi, A

    2010-02-01

    An innovative high-power constant-current (CC) pulsed-arc (PA) power-supply (PS) indispensable for a high-density PA plasma ion-source using a lanthanum hexaboride (LaB(6)) filament was devised by combining a constant-voltage (CV) PA-PS, which is composed of an insulated gate bipolar transistor (IGBT) switch, a CV direct-current (dc) PS and a 270 mF capacitor with a CC-PA-PS, which is composed of an IGBT-switch, a CC-dc-PS and a 400 microH inductor, through the inductor. The hybrid-CC-PA-PS succeeded in producing a flat arc-pulse with a peak power of 56 kW (400 A x 140 V) and a duty factor of more than 1.5% (600 micros x 25 Hz) for Japan Proton Accelerator Research Complex (J-PARC) H(-) ion-source stably. It also succeeded in shortening the 99% rising-time of the arc-pulse-current to about 20 micros and tilting up or down the arc-pulse-current arbitrarily and almost linearly by changing the setting voltage of its CV-dc-PS.

  11. An innovative high-power constant-current pulsed-arc power-supply for a high-density pulsed-arc-plasma ion-source using a LaB{sub 6}-filament

    SciTech Connect

    Ueno, A.; Oguri, H.; Ikegami, K.; Namekawa, Y.; Ohkoshi, K.; Tokuchi, A.

    2010-02-15

    An innovative high-power constant-current (CC) pulsed-arc (PA) power-supply (PS) indispensable for a high-density PA plasma ion-source using a lanthanum hexaboride (LaB{sub 6}) filament was devised by combining a constant-voltage (CV) PA-PS, which is composed of an insulated gate bipolar transistor (IGBT) switch, a CV direct-current (dc) PS and a 270 mF capacitor with a CC-PA-PS, which is composed of an IGBT-switch, a CC-dc-PS and a 400 {mu}H inductor, through the inductor. The hybrid-CC-PA-PS succeeded in producing a flat arc-pulse with a peak power of 56 kW (400 Ax140 V) and a duty factor of more than 1.5%(600 {mu}sx25 Hz) for Japan Proton Accelerator Research Complex (J-PARC) H{sup -} ion-source stably. It also succeeded in shortening the 99% rising-time of the arc-pulse-current to about 20 {mu}s and tilting up or down the arc-pulse-current arbitrarily and almost linearly by changing the setting voltage of its CV-dc-PS.

  12. An innovative high-power constant-current pulsed-arc power-supply for a high-density pulsed-arc-plasma ion-source using a LaB6-filament

    NASA Astrophysics Data System (ADS)

    Ueno, A.; Oguri, H.; Ikegami, K.; Namekawa, Y.; Ohkoshi, K.; Tokuchi, A.

    2010-02-01

    An innovative high-power constant-current (CC) pulsed-arc (PA) power-supply (PS) indispensable for a high-density PA plasma ion-source using a lanthanum hexaboride (LaB6) filament was devised by combining a constant-voltage (CV) PA-PS, which is composed of an insulated gate bipolar transistor (IGBT) switch, a CV direct-current (dc) PS and a 270 mF capacitor with a CC-PA-PS, which is composed of an IGBT-switch, a CC-dc-PS and a 400 μH inductor, through the inductor. The hybrid-CC-PA-PS succeeded in producing a flat arc-pulse with a peak power of 56 kW (400 A×140 V) and a duty factor of more than 1.5% (600 μs×25 Hz) for Japan Proton Accelerator Research Complex (J-PARC) H- ion-source stably. It also succeeded in shortening the 99% rising-time of the arc-pulse-current to about 20 μs and tilting up or down the arc-pulse-current arbitrarily and almost linearly by changing the setting voltage of its CV-dc-PS.

  13. Generation of high-energy sub-20 fs pulses tunable in the 250-310 nm region by frequency doubling of a high-power noncollinear optical parametric amplifier.

    PubMed

    Beutler, Marcus; Ghotbi, Masood; Noack, Frank; Brida, Daniele; Manzoni, Cristian; Cerullo, Giulio

    2009-03-15

    We report on the generation of powerful sub-20 fs deep UV pulses with 10 microJ level energy and broadly tunable in the 250-310 nm range. These pulses are produced by frequency doubling a high-power noncollinear optical parametric amplifier and compressed by a pair of MgF2 prisms to an almost transform-limited duration. Our results provide a power scaling by an order of magnitude with respect to previous works.

  14. High-power radio frequency pulse generation and extration based on wakefield excited by an intense charged particle beam in dielectric-loaded waveguides.

    SciTech Connect

    Gao, F.; High Energy Physics; Illinois Inst. of Tech

    2009-07-24

    Power extraction using a dielectric-loaded (DL) waveguide is a way to generate high-power radio frequency (RF) waves for future particle accelerators, especially for two-beam-acceleration. In a two-beam-acceleration scheme, a low-energy, high-current particle beam is passed through a deceleration section of waveguide (decelerator), where the power from the beam is partially transferred to trailing electromagnetic waves (wakefields); then with a properly designed RF output coupler, the power generated in the decelerator is extracted to an output waveguide, where finally the power can be transmitted and used to accelerate another usually high-energy low-current beam. The decelerator, together with the RF output coupler, is called a power extractor. At Argonne Wakefield Accelerator (AWA), we designed a 7.8GHz power extractor with a circular DL waveguide and tested it with single electron bunches and bunch trains. The output RF frequency (7.8GHz) is the sixth harmonic of the operational frequency (1.3GHz) of the electron gun and the linac at AWA. In single bunch excitation, a 1.7ns RF pulse with 30MW of power was generated by a single 66nC electron bunch passing through the decelerator. In subsequent experiments, by employing different splitting-recombining optics for the photoinjector laser, electron bunch trains were generated and thus longer RF pulses could be successfully generated and extracted. In 16-bunch experiments, 10ns and 22ns RF pulses have been generated and extracted; and in 4-bunch experiments, the maximum power generated was 44MW with 40MW extracted. A 26GHz DL power extractor has also been designed to test this technique in the millimeter-wave range. A power level of 148MW is expected to be generated by a bunch train with a bunch spacing of 769ps and bunch charges of 20nC each. The arrangement for the experiment is illustrated in a diagram. Higher-order-mode (HOM) power extraction has also been explored in a dual-frequency design. By using a bunch

  15. A simple method for experimental determination of electron temperature and electron density in a nanosecond pulsed longitudinal discharge used for excitation of high-power atomic and ionic metal and metal halide vapour lasers

    NASA Astrophysics Data System (ADS)

    Temelkov, K. A.; Vuchkov, N. K.

    2016-05-01

    A simple method based on the time-resolved measurement of electrical discharge parameters, such as tube voltage and discharge current, is developed and applied for determination of electron temperature and electron density in the discharge period of a nanosecond pulsed longitudinal discharge, exciting high-power DUV Cu+ Ne-CuBr, He-Hg+ and He-Sr+ lasers.

  16. Reactive pulsed-DC sputtered Nb-doped VO2 coatings for smart thermochromic windows with active solar control.

    PubMed

    Batista, C; Carneiro, J; Ribeiro, R M; Teixeira, V

    2011-10-01

    Thermochromic VO2 thin films have successfully been grown on SiO2-coated float glass by reactive pulsed-DC magnetron sputtering. Different Nb doping amounts were introduced in the VO2 solid solution during the film growing which resulted in films with distinct semiconducting-metal phase transition temperatures. Pure VO2 showed improved thermochromic behavior as compared with VO2 films prepared by conventional DC sputtering. The transition temperatures were linearly decreased from 59 down to 34 degrees C with the increase in Nb content. However, the luminous transmittance and the infrared modulation efficiency were markedly affected. The surface morphology of the films was examined by scanning electron microscopy (SEM) and showed a tendency for grain sized reduction due to Nb addition. Moreover, the films were found to be very dense with no columnar microstructure. Structural analyses carried out by X-ray diffractometry (XRD) revealed that Nb introduces significant amount of defects in the crystal lattice which clearly degrade the optical properties.

  17. Potential for reactive pulsed-dc magnetron sputtering of nanocomposite VO{sub x} microbolometer thin films

    SciTech Connect

    Jin, Yao O. Ozcelik, Adem; Horn, Mark W.; Jackson, Thomas N.

    2014-11-01

    Vanadium oxide (VO{sub x}) thin films were deposited by reactive pulsed-dc sputtering a metallic vanadium target in argon/oxygen mixtures with substrate bias. Hysteretic oxidation of the vanadium target surface was assessed by measuring the average cathode current during deposition. Nonuniform oxidization of the target surface was analyzed by Raman spectroscopy. The VO{sub x} film deposition rate, resistivity, and temperature coefficient of resistance were correlated to oxygen to argon ratio, processing pressure, target-to-substrate distance, and oxygen inlet positions. To deposit VO{sub x} in the resistivity range of 0.1–10 Ω-cm with good uniformity and process control, lower processing pressure, larger target-to-substrate distance, and oxygen inlet near the substrate are useful.

  18. Low-temperature pulsed sputtering growth of InGaN multiple quantum wells for photovoltaic devices

    NASA Astrophysics Data System (ADS)

    Arakawa, Yasuaki; Ueno, Kohei; Noguchi, Hidenari; Ohta, Jitsuo; Fujioka, Hiroshi

    2017-03-01

    We investigated the potential of low-temperature pulsed sputtering deposition (PSD) for the fabrication of high-In-composition thick InGaN multiple quantum wells (MQWs). Low-temperature PSD growth allowed the growth of a 100-period 1.2-nm-thick In0.3Ga0.7N MQW on GaN bulk crystals without apparent lattice relaxation. We fabricated a nitride-based photovoltaic device using 100-period In0.3Ga0.7N MQW absorption layers and obtained a clear photovoltaic response with an open-circuit voltage of 1.24 V, a short-circuit current density of 1.76 mA·cm‑2, and a maximum output power density of 1.10 mW·cm‑2 under 1 sun with air mass 1.5 illumination.

  19. Tunable optoelectronic properties of pulsed dc sputter-deposited ZnO:Al thin films: Role of growth angle

    NASA Astrophysics Data System (ADS)

    Kumar, Mohit; Singh, Ranveer; Nandy, Suman; Ghosh, Arnab; Rath, Satchidananda; Som, Tapobrata

    2016-07-01

    In this paper, we investigate the role of deposition angle on the physical properties and work function of pulsed dc sputter-deposited Al-doped zinc oxide (AZO) thin films. It is observed that average grain size and crystal quality increase with higher angle of deposition, yielding improved optical properties. A systematic blue shift as well as a decrease in the resistivity takes place with the increasing growth angle up to 70°, while an opposite trend is observed beyond that. In addition, the work function of AZO films is also measured using Kelvin probe force microscopy, which corroborates well with the optical and structural properties. The observed results are explained in the framework of growth angle induced diffusion and shadowing effects. The films deposited at higher angles will be important for rapid incorporation into new technological applications that require a transparent conductive oxide.

  20. The Development of a High-Power, Pulsed Mid-Infrared Laser for a Two-Photon LIF Detection of Tropospheric OH

    NASA Astrophysics Data System (ADS)

    Hannun, R. A.; Smith, J. B.; Witinski, M. F.; Anderson, J. G.

    2015-12-01

    The hydroxyl radical is universally recognized as the dominant oxidizing species in the earth's atmosphere. OH initiates the chemical transformation and degradation of greenhouse gases, pollutants, and volatile organic compounds and plays a critical role in both urban ozone pollution and aerosol formation. Because of its high reactivity, OH radicals have an atmospheric lifetime of less than a second and only reach mixing ratios of parts per trillion (ppt) in the free troposphere. The combination of these two factors makes in-situ observations of OH challenging. Laser-Induced Fluorescence (LIF) is a highly sensitive technique that has been successfully applied to measurements of stratospheric OH. The LIF technique has also been adapted to instrumentation for OH observations in the troposphere. However, results for tropospheric OH have been inconclusive due to poorly understood interferences, and large discrepancies exist between modeled and measured OH concentrations. A Two-Photon LIF (TP-LIF) technique has been proposed as a means of enhancing sensitivity by shifting to lower-energy pumping frequencies, which also minimizes laser-induced interference pathways. In this detection scheme, OH is pumped into an excited vibrational state and subsequently pumped into an excited electronic state. A major limitation in the sensitivity of the TP-LIF detection scheme has been the lack of a mid-infrared (mid-IR) light source with enough power to adequately pump the vibrational transition. We have developed a high-power, pulsed laser system at 2.97 μm using an optical parametric generator (OPG). The OPG system delivers narrow-linewidth, tunable radiation with high peak-power to substantially populate the vibrational excitation. The development of the OPG laser system effectively addresses the major challenge in the TP-LIF detection of OH.

  1. Development of High-Power, Long-Pulse Gyrotrons and Its Application for High Electron Temperature, EBWH and ECCD Experiments on LHD

    NASA Astrophysics Data System (ADS)

    Yoshimura, Y.; Kubo, S.; Shimozuma, T.; Igami, H.; Takahashi, H.; Nishiura, M.; Ito, S.; Kobayashi, S.; Mizuno, Y.; Okada, K.; Takita, Y.; Mutoh, T.; Yamada, H.; Komori, A.; Kariya, T.; Imai, T.; Marushchenko, Nikolai B.; Turkin, Yuri

    2011-12-01

    To sustain plasmas with higher parameters and with longer pulse duration in LHD, ECH system has been upgraded by introducing newly developed 77 GHz gyrotrons. The designed output power and operation duration time are over 1 MW for several seconds and 0.3 MW for continuous operation, respectively. Owing to the upgrade of gyrotrons and improved power supply operation procedure, total injection power of EC-waves to LHD increased up to 3.7 MW at the last LHD experimental campaign in 2010. Application of the high-power 77 GHz EC-waves of 3.4 MW as focused beams to the center of plasma with low line-average electron density of ˜0.2×1019m-3 causes highly steep electron temperature profile and the central electron temperature reached up to 20 keV, which highly exceeds the former record of 15 keV. At higher density region of 1×1019 m-3, central electron temperature reached 8.6 keV. Additional electron Bernstein wave heatings, O-X-B and slow X-B heatings, using a 77 GHz ECH system caused clear increase in plasma stored energy even for the high-density plasmas over plasma cutoff (>7.35×1019 m-3) sustained with NBI. For the O-X-B scenario, the 77 GHz EC-wave was obliquely injected from low-field side in O-mode polarization, aiming at the point where high mode-conversion efficiency was expected. For realizing slow X-B scenario, new inner-vessel mirrors were installed in LHD just close to a helical coil, that is, at the high-field side (HFS) region. Using the inner-vessel mirror, X-mode waves were injected from HFS, showing evident increase in plasma stored energy. Oblique injection of long-pulse 0.77 MW/8 s 77 GHz wave with various N∥ clearly demonstrated ECCD in LHD. The EC-driven current changes its direction with the sign of N∥, and the highest EC-driven current reached up to 42 kA.

  2. Development of High-Power, Long-Pulse Gyrotrons and Its Application for High Electron Temperature, EBWH and ECCD Experiments on LHD

    SciTech Connect

    Yoshimura, Y.; Kubo, S.; Shimozuma, T.; Igami, H.; Takahashi, H.; Nishiura, M.; Ito, S.; Kobayashi, S.; Mizuno, Y.; Okada, K.; Takita, Y.; Mutoh, T.; Yamada, H.; Komori, A.; Kariya, T.; Imai, T.; Marushchenko, Nikolai B.; Turkin, Yuri

    2011-12-23

    To sustain plasmas with higher parameters and with longer pulse duration in LHD, ECH system has been upgraded by introducing newly developed 77 GHz gyrotrons. The designed output power and operation duration time are over 1 MW for several seconds and 0.3 MW for continuous operation, respectively. Owing to the upgrade of gyrotrons and improved power supply operation procedure, total injection power of EC-waves to LHD increased up to 3.7 MW at the last LHD experimental campaign in 2010.Application of the high-power 77 GHz EC-waves of 3.4 MW as focused beams to the center of plasma with low line-average electron density of {approx}0.2x10{sup 19} m{sup -3} causes highly steep electron temperature profile and the central electron temperature reached up to 20 keV, which highly exceeds the former record of 15 keV. At higher density region of 1x10{sup 19} m{sup -3}, central electron temperature reached 8.6 keV.Additional electron Bernstein wave heatings, O-X-B and slow X-B heatings, using a 77 GHz ECH system caused clear increase in plasma stored energy even for the high-density plasmas over plasma cutoff (>7.35x10{sup 19} m{sup -3}) sustained with NBI. For the O-X-B scenario, the 77 GHz EC-wave was obliquely injected from low-field side in O-mode polarization, aiming at the point where high mode-conversion efficiency was expected. For realizing slow X-B scenario, new inner-vessel mirrors were installed in LHD just close to a helical coil, that is, at the high-field side (HFS) region. Using the inner-vessel mirror, X-mode waves were injected from HFS, showing evident increase in plasma stored energy.Oblique injection of long-pulse 0.77 MW/8 s 77 GHz wave with various N{sub ||} clearly demonstrated ECCD in LHD. The EC-driven current changes its direction with the sign of N{sub ||}, and the highest EC-driven current reached up to 42 kA.

  3. Assessing the performance and longevity of Nb, Pt, Ta, Ti, Zr, and ZrO₂-sputtered Havar foils for the high-power production of reactive [18F]F by proton irradiation of [18O]H2O.

    PubMed

    Gagnon, K; Wilson, J S; Sant, E; Backhouse, C J; McQuarrie, S A

    2011-10-01

    As water-soluble ionic contaminants, which arise following proton irradiation of [18O]H2O have been associated with decreased [18F]FDG yields, the minimization of these contaminants is an asset in improving the [18F]F reactivity. To this end, we have previously demonstrated that the use of Nb-sputtered Havar foils results in decreased radionuclidic and chemical impurities in proton irradiated [18O]H2O, improved [18F]FDG yields, and improved [18F]FDG yield consistency when compared with non-sputtered Havar. Resulting from the highly reactive chemical microenvironment within the target however, this niobium layer is observed to degrade over time. To find a material that displays increased longevity with regards to maintaining high [18F]F reactivity, this project extensively investigated and compared Havar foils sputtered with Nb, Pt, Ta, Ti, Zr and ZrO₂. Of the materials investigated, the results of this study suggest that Ta-sputtered Havar foil is the preferred choice. For similar integrated currents (~1,000,000 μA min), when comparing the Ta-sputtered Havar with Nb-sputtered Havar we observed: (i) greater than an order of magnitude decrease in radionuclidic impurities, (ii) a 6.4 percent increase (p=0.0025) in the average TracerLab MX [18F]FDG yield, and (iii) an overall improvement in the FDG yield consistency. Excellent performance of the Ta-sputtered foil was maintained throughout its ~1,500,000 μA min lifetime.

  4. Comparative Study of As-Deposited ZnO Thin Films by Thermal Evaporation, Pulsed Laser Deposition and RF Sputtering Methods for Electronic and Optoelectronic Applications

    NASA Astrophysics Data System (ADS)

    Vyas, Sumit; Giri, Pushpa; Singh, Shaivalini; Chakrabarti, P.

    2015-10-01

    Zinc oxide (ZnO) thin films have been deposited on Si substrate and glass substrate using thermal evaporation, pulsed laser deposition (PLD) and radio-frequency (RF) sputtering methods. The structural, surface morphological, optical and electrical properties of ZnO thin films deposited by these three methods were investigated and compared systematically using x-ray diffractometer, atomic force microscopy, ellipsometric and current-voltage ( I- V) measurement. The ZnO films deposited by RF sputtering method were highly oriented along the (002) plane. The ZnO films grown by thermal evaporation and PLD methods exhibited a polycrystalline nature. The surface roughness was found to be the least and the transparency in the visible region was the highest for the films grown by the RF sputtering method as compared to the films grown by the other two methods. The I- V characteristics reveal that the Pd:Au/ZnO (RF-sputtered) Schottky contact exhibited a better value of ideality factor, series resistance and barrier height as compared to the values obtained for Pd:Au/ZnO (thermally evaporated and pulse laser-deposited) Schottky contacts. The optical bandgap was found to be almost the same for the films grown by all three methods and was estimated to be around 3.2 eV.

  5. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Calculation of mass transfer in the remote cutting of metals by radiation of a high-power repetitively pulsed CO2 laser

    NASA Astrophysics Data System (ADS)

    Gladush, G. G.; Rodionov, N. B.

    2002-01-01

    The mechanism of remote cutting of steel plates by radiation of a high-power repetitively pulsed CO2 laser is theoretically studied. The models of melt removal by the gravity force and the recoil pressure of material vapour are proposed and the sufficient conditions for the initiation of cutting are determined. A numerical model of a thermally thin plate was employed to describe the cutting for large focal spots.

  6. Effects of pulsed sputtering frequency on the uniformity of Al:ZnO's transparent conductive oxide properties for solar cell applications

    SciTech Connect

    Yang, Wonkyun; Joo, Junghoon

    2009-11-15

    Bipolar pulsed magnetron sputtering is used to deposit Al doped ZnO (AZO) on a glass substrate for a transparent conducting oxide in a solar cell structure. A 5x25 in.{sup 2} AZO target was sputtered by 50-250 kHz bipolar pulsed dc power supply to deposit a 400x400 mm{sup 2} area by swinging back and forth. Sheet resistance, surface morphology, and optical transmittance were measured at different positions on 16 witness samples (small glass slides) to evaluate uniformity. In the thickness of 800 nm, the average value of sheet resistance was 30 {Omega}/{open_square} and the average resistivity was 2.1x10{sup -3} {Omega} cm. Transmittance was 50%-80% over the visible range. The nonuniformities of thickness, transmittance, and resistivity in the 400x400 mm{sup 2} area were 5.8%, 0.8%, and within 9.5%, respectively.

  7. IV INTERNATIONAL CONFERENCE ON ATOM AND MOLECULAR PULSED LASERS (AMPL'99): Radiative and photochemical properties of organic compounds excited by high-power XeCl laser radiation

    NASA Astrophysics Data System (ADS)

    Kopylova, T. N.; Kuznetsova, Rimma T.; Svetlichnyi, Valerii A.; Sergeev, A. K.; Tel'minov, E. N.; Filinov, D. N.

    2000-06-01

    Radiative and photochemical properties of a number of laser dyes excited by focused radiation of a XeCl laser with intensity up to 200 MW cm-2 were studied. A method for measuring the gain of organic molecules under high-power excitation is proposed. The dependence of the dye transmittance for the pump radiation on its intensity was studied. It is shown that changes in energy, spectral, and time characteristics of radiation and the photostability of compounds under high-power excitation are associated with the formation of superluminescence.

  8. Exciton dynamics of CdS thin films produced by chemical bath deposition and DC pulse sputtering.

    PubMed

    Cooper, Jason K; Cao, Jinbo; Zhang, Jin Z

    2013-08-14

    Exciton dynamics of CdS films have been investigated using ultrafast laser spectroscopy with an emphasis on understanding defect-related recombination. Two types of CdS films were deposited on glass substrates via direct current pulse sputtering (DCPS) and chemical bath deposition (CBD) techniques. The films displayed distinct morphological, optical, and structural properties. Their exciton and charge carrier dynamics within the first 1 ns following photoexcitation were characterized by femotosecond pump probe spectroscopy. A singular value decomposition (SVD) global fitting technique was employed to extract the lifetime and wavelength dependence of transient species. The excited electrons of the DCPS sample decays through 1.8, 8, 65, and 450 ps time constants which were attributed to donor level electron trapping, valence band (VB) → conduction band (CB) recombination, shallow donor recombination, and deep donor recombination, respectively. The CBD sample shows time constants of 6, 65, and 450 ps which were attributed to CB → VB recombination, sulfur vacancy (VS) recombination, and VS → oxygen interstitial (Oi) donor-acceptor pair (DAP) recombination, respectively. It was found that the DCPS deposition technique produces films with lower defect density and improved carrier dynamics, which are important for high performance solar cell applications.

  9. Correlations between structure, composition and electrical properties of tungsten/tungsten oxide periodic multilayers sputter deposited by gas pulsing

    NASA Astrophysics Data System (ADS)

    Potin, Valérie; Cacucci, Arnaud; Martin, Nicolas

    2017-01-01

    W/WOx multilayered thin films have been deposited by DC reactive sputtering using the reactive gas pulsing process. It is implemented to produce regular alternations of metal-oxide compounds at the nanometric scale. Structure and growth have been investigated by high resolution transmission electron microscopy, scanning transmission electron microscopy, X-ray energy dispersive spectroscopy and electron energy loss spectroscopy. Regularity of tungsten-based alternations, quality of interfaces as well as oxygen presence through the multilayered structure have been determined and linked to the growth conditions. Chemical information was obtained from the energy dispersive X-ray spectroscopy and low-loss electron energy loss spectroscopy. As they can be related to the chemical composition of the periodic layers, the position and the broadening of the bulk plasmon peak were studied. For the smallest periods (<10 nm), the presence of oxygen has been pointed out in the metal-rich layer whereas for the thickest ones (100 nm), pure metal is only present. Finally, relationships have been established between in situ growth conditions, structural and chemical parameters and electrical properties in periodic multilayers.

  10. The impact of hybrid energy storage on power quality, when high power pulsed DC loads are operated on a microgrid testbed

    NASA Astrophysics Data System (ADS)

    Kelley, Jay Paul

    As the Navy's demands for high power transient loads evolves, so too does the need for alternative energy sources to back-up the more traditional power generation. Such applications in need of support include electrical grid backup and directed energy weapon systems such as electromagnetic launchers, laser systems, and high power microwave generators, among others. Among the alternative generation sources receiving considerable attention are energy storage devices such as rechargeable electrochemical batteries and capacitors. In such applications as those mentioned above, these energy storage devices offer the ability to serve a dual role as both a power source to the various loads as well high power loads themselves to the continual generation when the high power transient loads are in periods of downtime. With the recent developments in electrochemical energy storage, lithium-ion batteries (LIBs) seem like the obvious choice, but previous research has shown that the elevated rates of charging can be detrimental to both the cycle life and the operational life span of the device. In order to preserve the batteries, their charge rate must be limited. One proposed method to accomplish the dual role task mentioned above, while preserving the life of the batteries, is by combining high energy density LIBs with high power density electric double layer capacitors (EDLCs) or lithium-ion capacitors (LICs) using controllable power electronics to adjust the flow of power to and from each device. Such a configuration is typically referred to as hybrid energy storage module (HESM). While shipboard generators start up, the combined high energy density and high power density of the HESM provides the capability to source critical loads for an extended period of time at the high rates they demand. Once the generator is operationally efficient, the HESM can act as a high energy reservoir to harvest the energy from the generator while the loads are in short periods of inactivity

  11. Kinetic simulation of neutral particle transport in sputtering processes

    NASA Astrophysics Data System (ADS)

    Trieschmann, Jan; Gallian, Sara; Brinkmann, Ralf Peter; Mussenbrock, Thomas; Ries, Stefan; Bibinov, Nikita; Awakowicz, Peter

    2013-09-01

    For many physical vapor deposition applications using sputtering processes, knowledge about the detailed spatial and temporal evolution of the involved gas species is of great importance. Modeling of the involved gas dynamic and plasma processes is however challenging, because the operating pressure is typically below 1 Pa. In consequence, only kinetic descriptions are appropriate. In order to approach this problem, the dynamics of sputtered particle transport through a neutral gas background is simulated. For this study, a modified version of the three-dimensional Direct Simulation Monte Carlo (DSMC) code dsmcFoam is utilized. The impact of a transient sputtering wind is investigated in a generic reactor geometry, which may be used for dc Magnetron Sputtering (dcMS), High Power Impulse Magnetron Sputtering (HiPIMS), as well as sputtering in capacitively coupled discharges. In the present work a rarefaction of the background gas is observed. Moreover in pulsed mode the temporal dynamics of the rarefaction and subsequent recovery of the background gas is investigated. This work is supported by the German Research Foundation in the frame of TRR 87.

  12. High-rate deposition of MgO by reactive ac pulsed magnetron sputtering in the transition mode

    SciTech Connect

    Kupfer, H.; Kleinhempel, R.; Richter, F.; Peters, C.; Krause, U.; Kopte, T.; Cheng, Y.

    2006-01-15

    A reactive ac pulsed dual magnetron sputtering process for MgO thin-film deposition was equipped with a closed-loop control of the oxygen flow rate (F{sub O2}) using the 285 nm magnesium radiation as input. Owing to this control, most of the unstable part of the partial pressure versus flowrate curve became accessible. The process worked steadily and reproducible without arcing. A dynamic deposition rate of up to 35 nm m/min could be achieved, which was higher than in the oxide mode by about a factor of 18. Both process characteristics and film properties were investigated in this work in dependence on the oxygen flow, i.e., in dependence on the particular point within the transition region where the process is operated. The films had very low extinction coefficients (<5x10{sup -5}) and refractive indices close to the bulk value. They were nearly stoichiometric with a slight oxygen surplus (Mg/O=48/52) which was independent of the oxygen flow. X-ray diffraction revealed a prevailing (111) orientation. Provided that appropriate rf plasma etching was performed prior to deposition, no other than the (111) peak could be detected. The intensity of this peak increased with increasing F{sub O{sub 2}}, indicating an even more pronounced (111) texture. The ion-induced secondary electron emission coefficient (iSEEC) was distinctly correlated with the markedness of the (111) preferential orientation. Both refractive index and (111) preferred orientation (which determines the iSEEC) were found to be improved in comparison with the MgO growth in the fully oxide mode. Consequently, working in the transition mode is superior to the oxide mode not only with respect to the growth rate, but also to most important film properties.

  13. Moderate high power 1 to 20μs and kHz Ho:YAG thin disk laser pulses for laser lithotripsy

    NASA Astrophysics Data System (ADS)

    Renz, Günther

    2015-02-01

    An acousto-optically or self-oscillation pulsed thin disk Ho:YAG laser system at 2.1 μm with an average power in the 10 W range will be presented for laser lithotripsy. In the case of cw operation the thin disk Ho:YAG is either pumped with InP diode stacks or with a thulium fiber laser which leads to a laser output power of 20 W at an optical-to-optical efficiency of 30%. For the gain switched mode of operation a modulated Tm-fiber laser is used to produce self-oscillation pulses. A favored pulse lengths for uric acid stone ablation is known to be at a few μs pulse duration which can be delivered by the thin disk laser technology. In the state of the art laser lithotripter, stone material is typically ablated with 250 to 750 μs pulses at 5 to 10 Hz and with pulse energies up to a few Joule. The ablation mechanism is performed in this case by vaporization into stone dust and fragmentation. With the thin disk laser technology, 1 to 20 μs-laser pulses with a repetition rate of a few kHz and with pulse energies in the mJ-range are available. The ablation mechanism is in this case due to a local heating of the stone material with a decomposition of the crystalline structure into calcium carbonate powder which can be handled by the human body. As a joint process to this thermal effect, imploding water vapor bubbles between the fiber end and the stone material produce sporadic shock waves which help clear out the stone dust and biological material.

  14. Doping management for high-power fiber lasers: 100 W, few-picosecond pulse generation from an all-fiber-integrated amplifier.

    PubMed

    Elahi, P; Yılmaz, S; Akçaalan, O; Kalaycıoğlu, H; Oktem, B; Senel, C; Ilday, F Ö; Eken, K

    2012-08-01

    Thermal effects, which limit the average power, can be minimized by using low-doped, longer gain fibers, whereas the presence of nonlinear effects requires use of high-doped, shorter fibers to maximize the peak power. We propose the use of varying doping levels along the gain fiber to circumvent these opposing requirements. By analogy to dispersion management and nonlinearity management, we refer to this scheme as doping management. As a practical first implementation, we report on the development of a fiber laser-amplifier system, the last stage of which has a hybrid gain fiber composed of high-doped and low-doped Yb fibers. The amplifier generates 100 W at 100 MHz with pulse energy of 1 μJ. The seed source is a passively mode-locked fiber oscillator operating in the all-normal-dispersion regime. The amplifier comprises three stages, which are all-fiber-integrated, delivering 13 ps pulses at full power. By optionally placing a grating compressor after the first stage amplifier, chirp of the seed pulses can be controlled, which allows an extra degree of freedom in the interplay between dispersion and self-phase modulation. This way, the laser delivers 4.5 ps pulses with ~200 kW peak power directly from fiber, without using external pulse compression.

  15. Characterizing rapid capacity fade and impedance evolution in high rate pulsed discharged lithium iron phosphate cells for complex, high power loads

    NASA Astrophysics Data System (ADS)

    Wong, Derek N.; Wetz, David A.; Heinzel, John M.; Mansour, Azzam N.

    2016-10-01

    Three 26650 LiFePO4 (LFP) cells are cycled using a 40 A pulsed charge/discharge profile to study their performance in high rate pulsed applications. This profile is used to simulate naval pulsed power loads planned for deployment aboard future vessels. The LFP cells studied experienced an exponential drop in their usable high-rate recharge capacity within sixty cycles due to a rapid rise in their internal resistance. Differential capacitance shows that the voltage window for charge storage is pushed outside of the recommended voltage cutoff limits. Investigation into the state of health of the electrodes shows minimal loss of active material from the cathode to side reactions. Post-mortem examination of the anodic surface films reveals a large increase in the concentration of reduced salt compounds indicating that the pulsed profile creates highly favorable conditions for LiPF6 salt to break down into LiF. This film slows the ionic movement at the interface, affecting transfer kinetics, resulting in charge buildup in the bulk anode without successful energy storage. The results indicate that the use of these cells as a power supply for high pulsed power loads is hindered because of ionically resistant film development and not by an increasing rate of active material loss.

  16. Emittance of short-pulsed high-current ion beams formed from the plasma of the electron cyclotron resonance discharge sustained by high-power millimeter-wave gyrotron radiation

    NASA Astrophysics Data System (ADS)

    Razin, S.; Zorin, V.; Izotov, I.; Sidorov, A.; Skalyga, V.

    2014-02-01

    We present experimental results on measuring the emittance of short-pulsed (≤100 μs) high-current (80-100 mA) ion beams of heavy gases (Nitrogen, Argon) formed from a dense plasma of an ECR source of multiply charged ions (MCI) with quasi-gas-dynamic mode of plasma confinement in a magnetic trap of simple mirror configuration. The discharge was created by a high-power (90 kW) pulsed radiation of a 37.5-GHz gyrotron. The normalized emittance of generated ion beams of 100 mA current was (1.2-1.3) π mm mrad (70% of ions in the beams). Comparing these results with those obtained using a cusp magnetic trap, it was concluded that the structure of the trap magnetic field lines does not exert a decisive influence on the emittance of ion beams in the gas-dynamic ECR source of MCI.

  17. Development, testing, and initial space qualification of 1.5-μm, high-power (6 W), pulse-position-modulated fiber laser transmitter for deep-space laser communication

    NASA Astrophysics Data System (ADS)

    Gupta, Shantanu; Engin, Doruk; Pachowicz, Dave; Fouron, Jean-Luc; Lander, Juan; Dang, Xung; Litvinovitch, Slava; Chuang, Ti; Puffenberger, Kent; Kimpel, Frank; Utano, Rich; Wright, Malcolm

    2016-11-01

    We report on the development, testing, and initial space qualification of a 1.5-μm, high-power (6 W), high wall-plug efficiency (˜15%), pulse-position-modulated (PPM), polarization-maintaining, fiber laser transmitter subsystem for deep-space laser communication links. Programmable high-order PPM modulation up to PPM-128 formats, with discrete pulse slots ranging from 0.5 to 8 ns, satisfies variety of link requirements for deep-space laser communication to Mars, asteroids, and other deep-space relay links, as per the National Aeronautics and Space Administration's space laser communication roadmap. We also present initial space qualification results from thermal-vacuum tests, vibration testing, radiation testing, and an overall reliability assessment.

  18. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Dependence of pressure in a compressed condensed matter on parameters of high-power laser pulses

    NASA Astrophysics Data System (ADS)

    Lebo, A. I.; Lebo, I. G.; Batani, D.

    2008-08-01

    Based on analysis of two-dimensional numerical calculations and experiments performed on the PALS setup, the similarity relations are obtained for determining pressure in a condensed matter irradiated by a short laser pulse of intensity 5×1013-5×1014 W cm-2.

  19. Picosecond green and deep ultraviolet pulses generated by a high-power 100  kHz thin-disk laser.

    PubMed

    Novák, Ondřej; Turčičová, Hana; Smrž, Martin; Miura, Taisuke; Endo, Akira; Mocek, Tomáš

    2016-11-15

    We report on the generation of the second (515 nm) and fourth (257.5 nm) harmonics from a 100 kHz diode-pumped solid-state laser operating at a wavelength of 1030 nm which uses one Yb:YAG thin disk in the regenerative amplifier and delivers 60 W of the average output power in pulses of 4 ps duration. Thirty-five W in green light and 6 W in deep ultraviolet (DUV) were achieved. The sensitivity of the second harmonic generation efficiency toward the lithium triborate crystal temperature is demonstrated in experiment. The overall conversion efficiency from NIR to DUV of 10% was achieved. The β-barium borate and cesium lithium borate crystals were used as green to DUV convertors and compared regarding the efficiency and spectral bandwidths. The achieved output power is unique for DUV picosecond pulses.

  20. Coupling output of multichannel high power microwaves

    SciTech Connect

    Li Guolin; Shu Ting; Yuan Chengwei; Zhang Jun; Yang Jianhua; Jin Zhenxing; Yin Yi; Wu Dapeng; Zhu Jun; Ren Heming; Yang Jie

    2010-12-15

    The coupling output of multichannel high power microwaves is a promising technique for the development of high power microwave technologies, as it can enhance the output capacities of presently studied devices. According to the investigations on the spatial filtering method and waveguide filtering method, the hybrid filtering method is proposed for the coupling output of multichannel high power microwaves. As an example, a specific structure is designed for the coupling output of S/X/X band three-channel high power microwaves and investigated with the hybrid filtering method. In the experiments, a pulse of 4 GW X band beat waves and a pulse of 1.8 GW S band microwave are obtained.

  1. High power laser apparatus and system

    NASA Technical Reports Server (NTRS)

    Evans, J. C., Jr.; Brandhorst, H. W., Jr. (Inventor)

    1975-01-01

    A high-power, continuous-wave laser was designed for use in power transmission and energy-collecting systems, and for producing incoherent light for pumping a laser material. The laser has a high repetitive pulsing rate per unit time, resulting in a high-power density beam. The laser is composed of xenon flash tubes powered by fast-charging capacitors flashed in succession by a high-speed motor connected to an automobile-type distributor.

  2. Dependence of the specific features of two PAPVD methods: Impulse Plasma Deposition (IPD) and Pulsed Magnetron Sputtering (PMS) on the structure of Fe-Cu alloy layers

    NASA Astrophysics Data System (ADS)

    Nowakowska-Langier, Katarzyna; Chodun, Rafal; Nietubyc, Robert; Minikayev, Roman; Zdunek, Krzysztof

    2013-06-01

    This paper describes the study of the structural properties of the alloy layers prepared by two different, impulsively working PAPVD methods: the Pulsed Magnetron Sputtering (PMS) and the Impulse Plasma Deposition (IPD). The Fe-Cu alloy layers were synthesized. The results of our investigation revealed a nanocrystalline structure of the layers. The differences in the phase composition of the Fe-Cu alloy layers produced by these two methods were observed. The synthesis of the Fe-Cu layers by using the Pulsed Magnetron Sputtering method resulted in obtaining the two-phase, polycrystalline structures (fcc-Cu and bcc-Fe). In this case the clear evidence of mixing between the iron and copper atoms was not observed. The Fe-Cu layers deposited by the Impulse Plasma Deposition method were characterized by the non-equilibrium phase composition - the presence of one-phase supersaturated solid solution (fcc-Cu(Fe) or bcc-Fe(Cu)) was formed in immiscible systems. These results suggest a short-distance diffusion between the neighboring nanoparticles of the two metals (Cu and Fe) occurring during the IPD layers growth.

  3. High-power QCW microsecond-pulse solid-state sodium beacon laser with spiking suppression and D2b re-pumping.

    PubMed

    Bian, Qi; Bo, Yong; Zuo, Jun-wei; Guo, Chuan; Xu, Chang; Tu, Wei; Shen, Yu; Zong, Nan; Yuan, Lei; Gao, Hong-wei; Peng, Qin-jun; Chen, Hong-bin; Feng, Lu; Jin, Kai; Wei, Kai; Cui, Da-fu; Xue, Sui-jian; Zhang, Yu-dong; Xu, Zu-yan

    2016-04-15

    A 65 W quasi-continuous-wave microsecond-pulse solid-state sodium beacon laser tuned to the sodium D2a line has been developed with a linewidth of 0.3 GHz, beam quality of M2=1.38, and pulse width of 120 μs at a repetition rate of 500 Hz by sum-frequency mixing 1319 and 1064 nm diode-pumped Nd:YAG master-oscillator power-amplifier systems. The laser wavelength stability is less than ±0.15 GHz through feedback controlling. The laser spiking due to relaxation oscillations is suppressed by inserting frequency doublers in both 1319 and 1064 nm oscillators. Sodium D2b re-pumping is accomplished by tuning the frequency of the electro-optic modulator with the right D2a-D2b offset. A bright sodium laser guide star with a photon return of 1820 photons/cm2/s was achieved with the laser system when a 32 W circular polarized beam was projected to the sky during our field test at the Xinglong Observatory.

  4. A tuneable ultra-compact high-power, ultra-short pulsed, bright gamma-ray source based on bremsstrahlung radiation from laser-plasma accelerated electrons

    SciTech Connect

    Cipiccia, S.; Wiggins, S. M.; Shanks, R. P.; Islam, M. R.; Vieux, G.; Issac, R. C.; Brunetti, E.; Ersfeld, B.; Welsh, G. H.; Anania, M. P.; Jaroszynski, D. A.; Maneuski, D.; Shea, V. O.; Lemos, N. R. C.; Bendoyro, R. A.; Dias, J. M.; Bourgeois, N.; Ibbotson, T. P. A.; and others

    2012-03-15

    The laser driven plasma wakefield accelerator is a very compact source of high energy electrons. When the quasi-monoenergetic beam from these accelerators passes through dense material, high energy bremsstrahlung photons are emitted in a collimated beam with high flux. We show how a source based on this emission process can produce more than 10{sup 9} photons per pulse with a mean energy of 10 MeV. We present experimental results that show the feasibility of this method of producing high energy photons and compare the experimental results with GEANT4 Montecarlo simulations, which also give the scaling required to evaluate its suitability as method to produce radioisotopes via photo-nuclear reactions or for imaging applications.

  5. Applied research using a 30 GHz free-electron maser: Experimental study of interacton of high-power pulsed radiation with metals

    NASA Astrophysics Data System (ADS)

    Baev, V. G.; Vdovin, V. A.; Vikharev, A. A.; Ginzburg, N. S.; Golubev, I. I.; Golubykh, S. M.; Zaitsev, N. I.; Kaminsky, A. K.; Kovalev, Yu. A.; Kozlov, A. P.; Kratko, A. F.; Kryachko, I. A.; Kuzikov, S. V.; Lesnikovich, A. I.; Milevich, I. A.; Perel'shtein, E. A.; Peskov, N. Yu.; Petelin, M. I.; Sedykh, S. N.; Tyutyunnikov, S. I.; Fedotova, Yu. A.

    2012-01-01

    We describe a facility for testing the properties of different objects affected by a sequence of highpower pulses of the microwave electromagnetic field. The facility performance is implemented due to the power level and stability of the single-mode generation of a free electron maser with an output frequency of 30 GHz, which have been achieved at the Joint Institute for Nuclear Research and the Institute of Applied Physics of the Russian Academy of Sciences. This paper describes the experiments on studying of the thermal fatigue of the copper surface in a test cavity, which models the thermal regime of the accelerating structure of the CLIC project (CERN), as well as the experiments on irradiation of biological tissues, metal films, and nanoclusters.

  6. A tuneable ultra-compact high-power, ultra-short pulsed, bright gamma-ray source based on bremsstrahlung radiation from laser-plasma accelerated electrons

    NASA Astrophysics Data System (ADS)

    Cipiccia, S.; Wiggins, S. M.; Shanks, R. P.; Islam, M. R.; Vieux, G.; Issac, R. C.; Brunetti, E.; Ersfeld, B.; Welsh, G. H.; Anania, M. P.; Maneuski, D.; Lemos, N. R. C.; Bendoyro, R. A.; Rajeev, P. P.; Foster, P.; Bourgeois, N.; Ibbotson, T. P. A.; Walker, P. A.; Shea, V. O.; Dias, J. M.; Jaroszynski, D. A.

    2012-03-01

    The laser driven plasma wakefield accelerator is a very compact source of high energy electrons. When the quasi-monoenergetic beam from these accelerators passes through dense material, high energy bremsstrahlung photons are emitted in a collimated beam with high flux. We show how a source based on this emission process can produce more than 109 photons per pulse with a mean energy of 10 MeV. We present experimental results that show the feasibility of this method of producing high energy photons and compare the experimental results with GEANT4 Montecarlo simulations, which also give the scaling required to evaluate its suitability as method to produce radioisotopes via photo-nuclear reactions or for imaging applications.

  7. High Power Hall Thrusters

    NASA Technical Reports Server (NTRS)

    Jankovsky, Robert; Tverdokhlebov, Sergery; Manzella, David

    1999-01-01

    The development of Hall thrusters with powers ranging from tens of kilowatts to in excess of one hundred kilowatts is considered based on renewed interest in high power. high thrust electric propulsion applications. An approach to develop such thrusters based on previous experience is discussed. It is shown that the previous experimental data taken with thrusters of 10 kW input power and less can be used. Potential mass savings due to the design of high power Hall thrusters are discussed. Both xenon and alternate thruster propellant are considered, as are technological issues that will challenge the design of high power Hall thrusters. Finally, the implications of such a development effort with regard to ground testing and spacecraft intecrati'on issues are discussed.

  8. Role of the carbonate impurities on the surface state of pyrite and arsenopyrite under treatment by high power electromagnetic pulses (HPEMP): oxidation of 50-100 μm size particles

    NASA Astrophysics Data System (ADS)

    Filippova, I.; Chanturiya, V.; Filippov, L.; Ryazantseva, M.; Bunin, I.

    2013-03-01

    Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and Transmission Electron Microscopy (TEM) have shown the variation of surface phase compositions of carbonate bearing pyrite and arsenopyrite as a result of the combined action of chemical oxidation and thermal processes after the treatment by high power electromagnetic pulses (HPEMP). The monitoring of the surface phase composition allowed to determine the correlation between the treatment conditions, the surface phase composition, and the flotation yield. Thus, HPEMP treatment may be regarded as a tool controlling the surface composition and the sorption ability of flotation collector onto minerals surface, and therefore, allowing to control the hydrophobic-hydrophilic surface balance. It was confirmed in this study that the flotation of pyrite with xanthate as a result of the influence HPEMP may vary depending on the presence of impurities such as calcite.

  9. Thermal effect of large-diameter laser rod in multi-direction side-pump high power pulsed Nd:YAG laser amplifier

    NASA Astrophysics Data System (ADS)

    Nie, Shuzhen; Zhao, Tianzhuo; Fan, Zhongwei; Xiao, Hong

    2016-10-01

    In this paper, a 15-direction ring laser diode array is chosen as pumping source in order to get uniform pump in laser medium. The diameter of laser rod is 15mm for obtaining high output laser energy. A numerical model of the side-pump pulsed Nd:YAG laser amplifier is set up. The finite element method using Ansys software is adopted to analyze the time-varying thermal effect. In order to find the temperature influence of the pump light's distribution, the temperature distributions in laser rod loaded by 15-direction Gaussian beam and simplified uniform beam are calculated and the results are comparatively analyzed. Despite the highest temperature in laser rod is different, the whole variation trend is similar which indicates time-varying characteristic. The thermal lens effect is also calculated and the results indicate that the temperature gradient in the medium plays the most important role. This study could provide a simulation tool to evaluate the thermal effect of the laser amplifier.

  10. High Power Cryogenic Targets

    SciTech Connect

    Gregory Smith

    2011-08-01

    The development of high power cryogenic targets for use in parity violating electron scattering has been a crucial ingredient in the success of those experiments. As we chase the precision frontier, the demands and requirements for these targets have grown accordingly. We discuss the state of the art, and describe recent developments and strategies in the design of the next generation of these targets.

  11. High power density targets

    NASA Astrophysics Data System (ADS)

    Pellemoine, Frederique

    2013-12-01

    In the context of new generation rare isotope beam facilities based on high-power heavy-ion accelerators and in-flight separation of the reaction products, the design of the rare isotope production targets is a major challenge. In order to provide high-purity beams for science, high resolution is required in the rare isotope separation. This demands a small beam spot on the production target which, together with the short range of heavy ions in matter, leads to very high power densities inside the target material. This paper gives an overview of the challenges associated with this high power density, discusses radiation damage issues in targets exposed to heavy ion beams, and presents recent developments to meet some of these challenges through different projects: FAIR, RIBF and FRIB which is the most challenging. Extensive use of Finite Element Analysis (FEA) has been made at all facilities to specify critical target parameters and R&D work at FRIB successfully retired two major risks related to high-power density and heavy-ion induced radiation damage.

  12. The role of pulse length in target poisoning during reactive HiPIMS: application to amorphous HfO2

    NASA Astrophysics Data System (ADS)

    Ganesan, R.; Murdoch, B. J.; Treverrow, B.; Ross, A. E.; Falconer, I. S.; Kondyurin, A.; McCulloch, D. G.; Partridge, J. G.; McKenzie, D. R.; Bilek, M. M. M.

    2015-06-01

    In conventional reactive magnetron sputtering, target poisoning frequently leads to an instability that requires the reactive gas flow rate to be actively regulated to maintain a constant composition of the deposited layers. Here we demonstrate that the pulse length in high power impulse magnetron sputtering (HiPIMS) is important for determining the surface conditions on the target that lead to poisoning. By increasing the pulse length, a smooth transition can be achieved from a poisoned target condition (short pulses) to a quasi-metallic target condition (long pulses). Appropriate selection of pulse length eliminates the need for active regulation, enabling stable reactive magnetron sputter deposition of stoichiometric amorphous hafnium oxide (HfO2) from a Hf target. A model is presented for the reactive HiPIMS process in which the target operates in a partially poisoned mode with a distribution of oxide on its surface that depends on the pulse length.

  13. Explosive Emission Cathode Based on a Carbon Fiber for Long-Term Pulsed-Periodic Mode of Operation and its Application in a High-Power Microwave Pulse Generator Without External Magnetic Field

    NASA Astrophysics Data System (ADS)

    Kutenkov, O. P.; Pegel, I. V.; Totmeninov, E. M.

    2014-09-01

    Current characteristics and operating lifetime of the explosive emission cathode based on a carbon microfiber are investigated in the pulsed-periodic mode of operation with pulse duration of about 5 ns. Long-term (for up to 3.6 million pulses) tests of the cathode operating lifetime are carried out. Specific ablation of the fiber material equal to 2.4·10-4 g/C is obtained. Change in the morphology of the fiber surface during long-time operation caused by deposition of carbon from the cathode plasma is revealed. The microscopic electric field strength on the fiber surface is estimated taking into account the surface microrelief. The efficiency of microwave generation comparable with that of a velvet cathode in low (200 kV/cm) average electric field in the gap is obtained for the Cherenkov microwave generator with vacuum diode without external magnetic field of decimeter wavelength range based on the SINUS-7 pulsed-periodic high-current electron accelerator with current pulse duration of 50 ns. The operating lifetime no less than 105 pulses is demonstrated for the carbon fiber-based cathode of the microwave generator operating in the mode of pulse batch with duration of several seconds and pulse repetition frequency of 20-50 Hz.

  14. High Rate Deposition of Thick CrN and Cr2N Coatings Using Modulated Pulse Power (MPP) Magnetron Sputtering

    DTIC Science & Technology

    2010-12-01

    skilled in the art , can overcome many of the above listed disadvantages for the different coating techniques. Sputtering is a very flexible and...J. Pelleg, L.Z. Zevin, S. Lungo and N. Croitoru Thin Solid Films 197 (1991) 117. [32] C. Nouveau , M.A. Djouadi, O...2004) 1306. [52] A.J. Perry. Thin Solid Films 107 (1983)167. [53] M. -A. Djouadi, C. Nouveau , O. Banakh, R. Sanjinés, F. Lévy and G. Nouet

  15. Membrane patterned by pulsed laser micromachining for proton exchange membrane fuel cell with sputtered ultra-low catalyst loadings

    NASA Astrophysics Data System (ADS)

    Cuynet, S.; Caillard, A.; Kaya-Boussougou, S.; Lecas, T.; Semmar, N.; Bigarré, J.; Buvat, P.; Brault, P.

    2015-12-01

    Proton exchange membranes were nano- and micro-patterned on their cathode side by pressing them against stainless steel molds previously irradiated by a Ti:Sapphire femtosecond laser. The membranes were associated to ultra-low loaded thin catalytic layers (25 μgPt cm-2) prepared by plasma magnetron sputtering. The Pt catalyst was sputtered either on the membrane or on the porous electrode. The fuel cell performance in dry conditions were found to be highly dependent on the morphology of the membrane surface. When nanometric ripples covered by a Pt catalyst were introduced on the surface of the membrane, the fuel cell outperformed the conventional one with a flat membrane. By combining nano- and micro-patterns (nanometric ripples and 11-24 μm deep craters), the performance of the cells was clearly enhanced. The maximum power density achieved by the fuel cell was multiplied by a factor of 3.6 (at 50 °C and 3 bar): 438 mW cm-2 vs 122 mW cm-2. This improvement is due to high catalyst utilization with a high membrane conductivity. When Pt is sputtered on the porous electrode (and not on the membrane), the contribution of the patterned membrane to the fuel cell efficiency was less significant, except in the presence of nanometric ripples. This result suggests that the patterning of the membrane must be consistent with the way the catalyst is synthesized, on the membrane or on the porous electrode.

  16. Study of sterilization-treatment in pure and N- doped carbon thin films synthesized by inductively coupled plasma assisted pulsed-DC magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Javid, Amjed; Kumar, Manish; Han, Jeon Geon

    2017-01-01

    Electrically-conductive nanocrystalline carbon films, having non-toxic and non-immunogenic characteristics, are promising candidates for reusable medical devices. Here, the pure and N- doped nanocrystalline carbon films are deposited by the assistance of inductively coupled plasma (ICP) in an unbalanced facing target pulsed-DC magnetron sputtering process. Through the optical emission spectroscopy study, the role of ICP assistance and N-doping on the reactive components/radicals during the synthesis is presented. The N-doping enhances the three fold bonding configurations by increasing the ionization and energies of the plasma species. Whereas, the ICP addition increases the plasma density to control the deposition rate and film structure. As a result, sputtering-throughput (deposition rate: 31-55 nm/min), electrical resistivity (4-72 Ωcm) and water contact angle (45.12°-54°) are significantly tailored. Electric transport study across the surface microchannel confirms the superiority of N-doped carbon films for sterilization stability over the undoped carbon films.

  17. Targets for high power neutral beams

    SciTech Connect

    Kim, J.

    1980-01-01

    Stopping high-power, long-pulse beams is fast becoming an engineering challenge, particularly in neutral beam injectors for heating magnetically confined plasmas. A brief review of neutral beam target technology is presented along with heat transfer calculations for some selected target designs.

  18. High power arcjet

    NASA Technical Reports Server (NTRS)

    Auweter-Kurtz, M.; Glocker, B.; Goelz, T. M.; Habiger, H.; Kurtz, H. L.; Schrade, H. O.; Wegmann, T.

    1990-01-01

    The activities on the development of the high power arc jet HIPARC, the thrust balance, and plasma diagnostic probes are discussed. Modifications of the HIPARC design and a synopsis of the materials used are given. Further experimental results with the TT30 thruster in the 50 kW range are presented. Some first calibration measurements of the thrust balance are also included. Progress concerning the development of plasma diagnostic devices is documented.

  19. High power microwave generator

    DOEpatents

    Ekdahl, Carl A.

    1986-01-01

    A microwave generator efficiently converts the energy of an intense relativistic electron beam (REB) into a high-power microwave emission using the Smith-Purcell effect which is related to Cerenkov radiation. Feedback for efficient beam bunching and high gain is obtained by placing a cylindrical Smith-Purcell transmission grating on the axis of a toroidal resonator. High efficiency results from the use of a thin cold annular highly-magnetized REB that is closely coupled to the resonant structure.

  20. High power microwave generator

    DOEpatents

    Ekdahl, C.A.

    1983-12-29

    A microwave generator efficiently converts the energy of an intense relativistic electron beam (REB) into a high-power microwave emission using the Smith-Purcell effect which is related to Cerenkov radiation. Feedback for efficient beam bunching and high gain is obtained by placing a cylindrical Smith-Purcell transmission grating on the axis of a toroidal resonator. High efficiency results from the use of a thin cold annular highly-magnetized REB that is closely coupled to the resonant structure.

  1. Measurement of deposition rate and ion energy distribution in a pulsed dc magnetron sputtering system using a retarding field analyzer with embedded quartz crystal microbalance.

    PubMed

    Sharma, Shailesh; Gahan, David; Scullin, Paul; Doyle, James; Lennon, Jj; Vijayaraghavan, Rajani K; Daniels, Stephen; Hopkins, M B

    2016-04-01

    A compact retarding field analyzer with embedded quartz crystal microbalance has been developed to measure deposition rate, ionized flux fraction, and ion energy distribution arriving at the substrate location. The sensor can be placed on grounded, electrically floating, or radio frequency (rf) biased electrodes. A calibration method is presented to compensate for temperature effects in the quartz crystal. The metal deposition rate, metal ionization fraction, and energy distribution of the ions arriving at the substrate location are investigated in an asymmetric bipolar pulsed dc magnetron sputtering reactor under grounded, floating, and rf biased conditions. The diagnostic presented in this research work does not suffer from complications caused by water cooling arrangements to maintain constant temperature and is an attractive technique for characterizing a thin film deposition system.

  2. Fabrication and characterization of the electrical and optical properties of n-type thin film transparent conducting oxides deposited by neutralized ion beam sputtering and pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Vanderford, John D.

    Transparent conducting oxides have become a fundamental electronic material for numerous current technologies and are optimally deposited as a uniform thin film with low electrical resistivity and high optical transmission. The purpose of this study is to characterize the electrical and optical characteristics of three TCO: Indium Tin Oxide (ITO) (95%, 5%), Zinc Oxide (ZnO), and Aluminum doped Zinc Oxide (AZO) (98%, 2%). The deposition techniques of neutralized ion beam sputtering and pulsed laser deposition will be investigated. ITO will be deposited from commercially available sintered targets whereas ZnO and AZO will be deposited from powder pressed targets. The results have shown that AZO deposit AZO from a powder pressed target with comparable electrical and optical properties to that of ITO deposited from a sintered target.

  3. High power microwave generator

    DOEpatents

    Minich, Roger W.

    1988-01-01

    A device (10) for producing high-powered and coherent microwaves is described. The device comprises an evacuated, cylindrical, and hollow real cathode (20) that is driven to inwardly field emit relativistic electrons. The electrons pass through an internally disposed cylindrical and substantially electron-transparent cylindrical anode (24), proceed toward a cylindrical electron collector electrode (26), and form a cylindrical virtual cathode (32). Microwaves are produced by spatial and temporal oscillations of the cylindrical virtual cathode (32), and by electrons that reflex back and forth between the cylindrical virtual cathode (32) and the cylindrical real cathode (20).

  4. High power arcjet

    NASA Technical Reports Server (NTRS)

    Goelz, T. M.; Auweter-Kurtz, M.; Kurtz, H. L.; Schrade, H. O.

    1991-01-01

    The activities of the High Power Arcjet Project (HIPARC) from August 1990 to January 1991 are discussed. In this period the HIPARC thruster was ignited for the first time. Power levels up to 140 kW with a mass flow rate of 300 mg/s hydrogen were reached. Specific impulse values of more than 1300 s were shown to be possible. Tests were performed with the baseline thruster version only, which has a 6 mm throat diameter and a conical nozzle with a 20 degree half angle. Measurement data summing up all tests carried out until now is included. All measuring methods are described, including a check on possible error sources.

  5. Elementary surface processes during reactive magnetron sputtering of chromium

    SciTech Connect

    Monje, Sascha; Corbella, Carles Keudell, Achim von

    2015-10-07

    The elementary surface processes occurring on chromium targets exposed to reactive plasmas have been mimicked in beam experiments by using quantified fluxes of Ar ions (400–800 eV) and oxygen atoms and molecules. For this, quartz crystal microbalances were previously coated with Cr thin films by means of high-power pulsed magnetron sputtering. The measured growth and etching rates were fitted by flux balance equations, which provided sputter yields of around 0.05 for the compound phase and a sticking coefficient of O{sub 2} of 0.38 on the bare Cr surface. Further fitted parameters were the oxygen implantation efficiency and the density of oxidation sites at the surface. The increase in site density with a factor 4 at early phases of reactive sputtering is identified as a relevant mechanism of Cr oxidation. This ion-enhanced oxygen uptake can be attributed to Cr surface roughening and knock-on implantation of oxygen atoms deeper into the target. This work, besides providing fundamental data to control oxidation state of Cr targets, shows that the extended Berg's model constitutes a robust set of rate equations suitable to describe reactive magnetron sputtering of metals.

  6. NASA GRC High Power Electromagnetic Thruster Program

    NASA Astrophysics Data System (ADS)

    Lapointe, Michael R.; Pencil, Eric J.

    2004-02-01

    Interest in high power electromagnetic propulsion has been revived to support a variety of future space missions, such as platform maneuvering in low earth orbit, cost-effective cargo transport to lunar and Mars bases, asteroid and outer planet sample return, deep space robotic exploration, and piloted missions to Mars and the outer planets. Magnetoplasmadynamic (MPD) thrusters have demonstrated, at the laboratory level, the capacity to process megawatts of electrical power while providing higher thrust densities than current electric propulsion systems. The ability to generate higher thrust densities permits a reduction in the number of thrusters required to perform a given mission and alleviates the system complexity associated with multiple thruster arrays. The specific impulse of an MPD thruster can be optimized to meet given mission requirements, from a few thousand seconds with heavier gas propellants up to 10,000 seconds with hydrogen propellant. In support of NASA space science and human exploration strategic initiatives, Glenn Research Center is developing and testing pulsed, MW-class MPD thrusters as a prelude to long-duration high power thruster tests. The research effort includes numerical modeling of self-field and applied-field MPD thrusters and experimental testing of quasi-steady MW-class MPD thrusters in a high power pulsed thruster facility. This paper provides an overview of the GRC high power electromagnetic thruster program and the pulsed thruster test facility.

  7. High Power Pulsed Plasma MHD Experiments.

    DTIC Science & Technology

    1982-09-30

    Associates Incorporated ARE A a WORK UNIT NUM11ERS 26046 Eden Landing Road Hayward, California 94545 11. CONTROLLING OFFICE NAME AND ADDRESS It. REPORT...Associates Incorporated 26046 Eden Landing Road Hayward, California 94545 Accession For Telephone: 415/785-8080 NTIS GRA&I g DTIC TAB 0 Unannounced...this report was sponsored by the Office of Naval Research Contract N00014-81-C-0045 under the direction of Dr. Bobby Junker and we gratefully

  8. High power coaxial ubitron

    NASA Astrophysics Data System (ADS)

    Balkcum, Adam J.

    In the ubitron, also known as the free electron laser, high power coherent radiation is generated from the interaction of an undulating electron beam with an electromagnetic signal and a static periodic magnetic wiggler field. These devices have experimentally produced high power spanning the microwave to x-ray regimes. Potential applications range from microwave radar to the study of solid state material properties. In this dissertation, the efficient production of high power microwaves (HPM) is investigated for a ubitron employing a coaxial circuit and wiggler. Designs for the particular applications of an advanced high gradient linear accelerator driver and a directed energy source are presented. The coaxial ubitron is inherently suited for the production of HPM. It utilizes an annular electron beam to drive the low loss, RF breakdown resistant TE01 mode of a large coaxial circuit. The device's large cross-sectional area greatly reduces RF wall heat loading and the current density loading at the cathode required to produce the moderate energy (500 keV) but high current (1-10 kA) annular electron beam. Focusing and wiggling of the beam is achieved using coaxial annular periodic permanent magnet (PPM) stacks without a solenoidal guide magnetic field. This wiggler configuration is compact, efficient and can propagate the multi-kiloampere electron beams required for many HPM applications. The coaxial PPM ubitron in a traveling wave amplifier, cavity oscillator and klystron configuration is investigated using linear theory and simulation codes. A condition for the dc electron beam stability in the coaxial wiggler is derived and verified using the 2-1/2 dimensional particle-in-cell code, MAGIC. New linear theories for the cavity start-oscillation current and gain in a klystron are derived. A self-consistent nonlinear theory for the ubitron-TWT and a new nonlinear theory for the ubitron oscillator are presented. These form the basis for simulation codes which, along

  9. High power 4.65 μm single-wavelength laser by second-harmonic generation of pulsed TEA CO2 laser in AgGaSe2 and ZnGeP2

    NASA Astrophysics Data System (ADS)

    Li, D. J.; Guo, J.; Yang, G. L.; Meng, F. J.; Zhang, L. M.; Xie, J. J.; Chen, F.; Shao, C. L.; Zhang, C. S.; Geng, Y. M.; Li, S. M.

    2012-04-01

    A high power 4.65 μm single-wavelength laser by second-harmonic generation (SHG) of TEA CO2 laser pulses in silver gallium selenide (AgGaSe2) and zinc germanium phosphide (ZnGeP2) crystals is reported. Experimental results show that the average output power of SHG laser is not only restricted by the damage threshold of the nonlinear crystals, but also limited by the irradiated power of fundamental-wave laser depending on the operating repetition-rate. It is found that ZnGeP2 can withstand higher 9.3 μm laser irradiation intensity than AgGaSe2. As a result, using a parallel array stacked by seven ZnGeP2 crystals, an average power of 20.3 W 4.65 μm laser is obtained at 250 Hz. To the best of our knowledge, it is the highest output power for SHG of CO2 laser by far.

  10. Studies on the room temperature growth of nanoanatase phase TiO2 thin films by pulsed dc magnetron with oxygen as sputter gas

    NASA Astrophysics Data System (ADS)

    Karuppasamy, A.; Subrahmanyam, A.

    2007-03-01

    The anatase phase titanium dioxide (TiO2) thin films were deposited at room temperature by pulsed dc magnetron sputtering using pure oxygen as sputter gas. The structural, optical, electrical, and electrochromic properties of the films have been studied as a function of oxygen pressure in the chamber. The x-ray diffraction results indicate that the films grown above 4.5×10-2mbar are nanocrystalline (grain size of 28-43nm) with anatase phase. The films deposited at the chamber pressure of 7.2×10-2mbar are found to be highly crystalline with a direct optical band gap of 3.40eV, refractive index of 2.54 (at λ =400nm), and work function of 4.77eV (determined by the Kelvin probe measurements). From the optical emission spectra of the plasma and transport of ions in matter calculations, we find that the crystallization of TiO2 at room temperature is due to the impingement of electrons and ions on the growing films. Particularly, the negative oxygen ions reflected from the target by "negative ion effects" and the enhanced density of TiO, TiO +, TiO2+, and O2+ particles in the plasma are found to improve the crystallization even at a relatively low temperature. From an application point of view, the film grown at 7.2×10-2mbar was studied for its electrochromic properties by protonic intercalation. It showed good electrochromic behavior with an optical modulation of ˜45%, coloration efficiency of 14.7 cm2C-1, and switching time (tc) of 50s for a 2×2 cm2 device at λ =633nm.

  11. High Power Modulator.

    DTIC Science & Technology

    1986-08-01

    The bushing consists of three segments of alumina tubing with interspersed metal rings. All metallic surfaces ex- *posed to vacuum are stainless steel...high voltage transient only lasted for several hundred ns, no vacuum insulator breakdown was noted during the tests. 4.2 Acceptance tests at PSI The...ation at 1 pps. The oil insulated output pulse transformer has multiple secondary windings which can be used to provide heater power for a thermionic

  12. High power connection system

    DOEpatents

    Schaefer, Christopher E.; Beer, Robert C.; McCall, Mark D.

    2000-01-01

    A high power connection system adapted for automotive environments which provides environmental and EMI shielding includes a female connector, a male connector, and a panel mount. The female connector includes a female connector base and a snap fitted female connector cover. The male connector includes a male connector base and a snap fitted male connector cover. The female connector base has at least one female power terminal cavity for seatably receiving a respective female power terminal. The male connector base has at least one male power terminal cavity for seatably receiving a respective male power terminal. The female connector is covered by a cover seal and a conductive shroud. A pair of lock arms protrude outward from the front end of the male connector base, pass through the panel mount and interface with a lever of a lever rotatably connected to the shroud to thereby mechanically assist mating of the male and female connectors. Safety terminals in the male and female connectors provide a last-to-connect-first-to-break connection with an HVIL circuit.

  13. High power, fast, microwave components based on beam generated plasmas

    NASA Astrophysics Data System (ADS)

    Manheimer, W. M.; Fernsler, R. F.; Gitlin, M. S.

    1998-10-01

    It is shown that the agile mirror plasma, under development as a device to simply and cheaply give electronic steering to microwave beams, also has application as a fast, electronically controlled, high power reflector, or phase shifter. In a radar system, this can lead to such applications as pulse to pulse polarization agility and electronic control of antenna gain, as well as to innovative approaches to high power millimeter wave circulators. The basic theory of the enhanced glow plasma is also developed.

  14. Rapid thermal annealing effect on the spatial resistivity distribution of AZO thin films deposited by pulsed-direct-current sputtering for solar cells applications

    NASA Astrophysics Data System (ADS)

    Ayachi, Boubakeur; Aviles, Thomas; Vilcot, Jean-Pierre; Sion, Cathy

    2016-03-01

    Room temperature deposited aluminium-doped zinc oxide thin films on glass substrate, using pulsed-DC magnetron sputtering, have shown high optical transmittance and low electrical resistivity with high uniformity of its spatial distribution after they were exposed to a rapid thermal annealing process at 400 °C under N2H2 atmosphere. It is particularly interesting to note that such an annealing process of AZO thin films for only 30 s was sufficient, on one hand to improve their optical transmittance from 73% to 86%, on the other hand to both decrease their resistivity from 1.7 × 10-3 Ω cm to 5.1 × 10-4 Ω cm and achieve the highest uniformity spatial distribution. To understand the mechanisms behind such improvements of the optoelectronic properties, electrical, optical, structural and morphological changes as a function of annealing time have been investigated by using hall measurement, UV-visible spectrometry, X-ray diffraction and scanning electron microscope imaging, respectively.

  15. Stress controlled pulsed direct current co-sputtered Al{sub 1−x}Sc{sub x}N as piezoelectric phase for micromechanical sensor applications

    SciTech Connect

    Fichtner, Simon; Reimer, Tim; Chemnitz, Steffen; Wagner, Bernhard; Lofink, Fabian

    2015-11-01

    Scandium alloyed aluminum nitride (Al{sub 1−x}Sc{sub x}N) thin films were fabricated by reactive pulsed direct current co-sputtering of separate scandium and aluminum targets with x ≤ 0.37. A significant improvement of the clamped transversal piezoelectric response to strain e{sub 31,f} from −1.28 C/m{sup 2} to −3.01 C/m{sup 2} was recorded, while dielectric constant and loss angle remain low. Further, the built-in stress level of Al{sub 1−x}Sc{sub x}N was found to be tuneable by varying pressure, Ar/N{sub 2} ratio, and Sc content. The thus resulting enhancement of the expectable signal to noise ratio by a factor of 2.1 and the ability to control built-in stress make the integration of Al{sub 1−x}Sc{sub x}N as the piezoelectric phase of micro-electro-mechanical system sensor applications highly attractive.

  16. Evaluation of the optoelectronic properties and corrosion behavior of Al2O3-doped ZnO films prepared by dc pulsed magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Zubizarreta, C.; Berasategui, E. G.; Bayón, R.; Escobar Galindo, R.; Barros, R.; Gaspar, D.; Nunes, D.; Calmeiro, T.; Martins, R.; Fortunato, E.; Barriga, J.

    2014-12-01

    The main requirements for transparent conducting oxide (TCO) films acting as electrodes are a high transmission rate in the visible spectral region and low resistivity. However, in many cases, tolerance to temperature and humidity exposure is also an important requirement to be fulfilled by the TCOs to assure proper operation and durability. Besides improving current encapsulation methods, the corrosion resistance of the developed TCOs must also be enhanced to warrant the performance of optoelectronic devices. In this paper the performance of aluminum-doped zinc oxide (AZO) films deposited by pulsed dc magnetron sputtering has been studied. Structure, optical transmittance/reflectance, electrical properties (resistivity, carrier concentration and mobility) and corrosion resistance of the developed coatings have been analyzed as a function of the doping of the target and the coating thickness. Films grown from a 2.0 wt% Al2O3 target with a thickness of approximately 1 µm showed a very low resistivity of 6.54  ×  10-4 Ωcm and a high optical transmittance in the visible range of 84%. Corrosion studies of the developed samples have shown very low corrosion currents (nanoamperes), very high corrosion resistances (in the order of 107 Ω) and very high electrochemical stability, indicating no tendency for electrochemical corrosion degradation.

  17. Electrical resistivity change in Al:ZnO thin films dynamically deposited by bipolar pulsed direct-current sputtering and a remote plasma source

    SciTech Connect

    Yang, Wonkyun; Joo, Junghoon

    2010-07-15

    The Al-doped ZnO (AZO) thin films for a transparent conducting oxide in solar cell devices were deposited by bipolar pulsed dc magnetron sputtering. This work was performed in an in-line type system and investigated AZO films in a static deposition mode and dynamic one, which is more important in the practical fields. Because of this dynamic deposition process, the zigzagged columnar structure was observed. This resulted in the decreasing electrical property, optical properties, and surface roughness. As a deposition in the dynamic mode, the resistivity increased from 1.64x10{sup -3} to 2.50x10{sup -3} {Omega} cm, as compared to that in the static mode, and the transmittance also decreased from 83.9% to 78.3%. To recover the disadvantage, a remote plasma source (RPS) was supported between the substrate and target for reducing zigzagged formation during the deposition. The deposition rate decreased by using RPS, but the electrical and optical properties of films got better than only dynamic mode. The resistivity and transmittance in the dynamic mode using RPS were 2.1x10{sup -3} {Omega} cm and 85.5%, respectively. In this study, the authors found the possibility to advance the electrical and optical properties of AZO thin films in the industry mode.

  18. Stretchers and compressors for ultra-high power laser systems

    SciTech Connect

    Yakovlev, I V

    2014-05-30

    This review is concerned with pulse stretchers and compressors as key components of ultra-high power laser facilities that take advantage of chirped-pulse amplification. The potentialities, characteristics, configurations and methods for the matching and alignment of these devices are examined, with particular attention to the history of the optics of ultra-short, ultra-intense pulses before and after 1985, when the chirped-pulse amplification method was proposed, which drastically changed the view of the feasibility of creating ultra-high power laser sources. The review is intended primarily for young scientists and experts who begin to address the amplification and compression of chirped pulses, experts in laser optics and all who are interested in scientific achievements in the field of ultra-high power laser systems. (review)

  19. High power beam analysis

    NASA Astrophysics Data System (ADS)

    Aharon, Oren

    2014-02-01

    In various modern scientific and industrial laser applications, beam-shaping optics manipulates the laser spot size and its intensity distribution. However the designed laser spot frequently deviates from the design goal due to real life imperfections and effects, such as: input laser distortions, optical distortion, heating, overall instabilities, and non-linear effects. Lasers provide the ability to accurately deliver large amounts of energy to a target area with very high accuracy. Thus monitoring beam size power and beam location is of high importance for high quality results and repeatability. Depending on the combination of wavelength, beam size and pulse duration , laser energy is absorbed by the material surface, yielding into processes such as cutting, welding, surface treatment, brazing and many other applications. This article will cover the aspect of laser beam measurements, especially at the focal point where it matters the most. A brief introduction to the material processing interactions will be covered, followed by fundamentals of laser beam propagation, novel measurement techniques, actual measurement and brief conclusions.

  20. Sputter target

    DOEpatents

    Gates, Willard G.; Hale, Gerald J.

    1980-01-01

    The disclosure relates to an improved sputter target for use in the deposition of hard coatings. An exemplary target is given wherein titanium diboride is brazed to a tantalum backing plate using a gold-palladium-nickel braze alloy.

  1. On the pressure effect in energetic deposition of Cu thin films by modulated pulsed power magnetron sputtering: A global plasma model and experiments

    NASA Astrophysics Data System (ADS)

    Zheng, B. C.; Meng, D.; Che, H. L.; Lei, M. K.

    2015-05-01

    The modulated pulsed power magnetron sputtering (MPPMS) discharge processes are numerically modeled and experimentally investigated, in order to explore the effect of the pressure on MPPMS discharges as well as on the microstructure of the deposited thin films. A global plasma model has been developed based on a volume-averaged global description of the ionization region, considering the loss of electrons by cross-B diffusion. The temporal variations of internal plasma parameters at different pressures from 0.1 to 0.7 Pa are obtained by fitting the model to duplicate the experimental discharge data, and Cu thin films are deposited by MPPMS at the corresponding pressures. The surface morphology, grain size and orientation, and microstructure of the deposited thin films are investigated by scanning electron microscopy, transmission electron microscopy, and x-ray diffraction. By increasing the pressure from 0.1 to 0.7 Pa, both the ion bombardment energy and substrate temperature which are estimated by the modeled plasma parameters decrease, corresponding to the observed transition of the deposited thin films from a void free structure with a wide distribution of grain size (zone T) into an underdense structure with a fine fiber texture (zone 1) in the extended structure zone diagram (SZD). The microstructure and texture transition of Cu thin films are well-explained by the extended SZD, suggesting that the primary plasma processes are properly incorporated in the model. The results contribute to the understanding of the characteristics of MPPMS discharges, as well as its correlation with the microstructure and texture of deposited Cu thin films.

  2. On the pressure effect in energetic deposition of Cu thin films by modulated pulsed power magnetron sputtering: A global plasma model and experiments

    SciTech Connect

    Zheng, B. C.; Meng, D.; Che, H. L.; Lei, M. K.

    2015-05-28

    The modulated pulsed power magnetron sputtering (MPPMS) discharge processes are numerically modeled and experimentally investigated, in order to explore the effect of the pressure on MPPMS discharges as well as on the microstructure of the deposited thin films. A global plasma model has been developed based on a volume-averaged global description of the ionization region, considering the loss of electrons by cross-B diffusion. The temporal variations of internal plasma parameters at different pressures from 0.1 to 0.7 Pa are obtained by fitting the model to duplicate the experimental discharge data, and Cu thin films are deposited by MPPMS at the corresponding pressures. The surface morphology, grain size and orientation, and microstructure of the deposited thin films are investigated by scanning electron microscopy, transmission electron microscopy, and x-ray diffraction. By increasing the pressure from 0.1 to 0.7 Pa, both the ion bombardment energy and substrate temperature which are estimated by the modeled plasma parameters decrease, corresponding to the observed transition of the deposited thin films from a void free structure with a wide distribution of grain size (zone T) into an underdense structure with a fine fiber texture (zone 1) in the extended structure zone diagram (SZD). The microstructure and texture transition of Cu thin films are well-explained by the extended SZD, suggesting that the primary plasma processes are properly incorporated in the model. The results contribute to the understanding of the characteristics of MPPMS discharges, as well as its correlation with the microstructure and texture of deposited Cu thin films.

  3. Measuring the energy flux at the substrate position during magnetron sputter deposition processes

    SciTech Connect

    Cormier, P.-A.; Thomann, A.-L.; Dussart, R.; Semmar, N.; Mathias, J.; Balhamri, A.; Snyders, R.; Konstantinidis, S.

    2013-01-07

    In this work, the energetic conditions at the substrate were investigated in dc magnetron sputtering (DCMS), pulsed dc magnetron sputtering (pDCMS), and high power impulse magnetron sputtering (HiPIMS) discharges by means of an energy flux diagnostic based on a thermopile sensor, the probe being set at the substrate position. Measurements were performed in front of a titanium target for a highly unbalanced magnetic field configuration. The average power was always kept to 400 W and the probe was at the floating potential. Variation of the energy flux against the pulse peak power in HiPIMS was first investigated. It was demonstrated that the energy per deposited titanium atom is the highest for short pulses (5 {mu}s) high pulse peak power (39 kW), as in this case, the ion production is efficient and the deposition rate is reduced by self-sputtering. As the argon pressure is increased, the energy deposition is reduced as the probability of scattering in the gas phase is increased. In the case of the HiPIMS discharge run at moderate peak power density (10 kW), the energy per deposited atom was found to be lower than the one measured for DCMS and pDCMS discharges. In these conditions, the HiPIMS discharge could be characterized as soft and close to a pulsed DCMS discharge run at very low duty cycle. For the sake of comparison, measurements were also carried out in DCMS mode with a balanced magnetron cathode, in the same working conditions of pressure and power. The energy flux at the substrate is significantly increased as the discharge is generated in an unbalanced field.

  4. Study of optical properties of asymmetric bipolar pulse DC magnetron sputtered Ta{sub 2}O{sub 5} thin film as a function of oxygen content in deposition ambient

    SciTech Connect

    Haque, S. Maidul Shinde, D. D. Misal, J. S.; Bhattacharyya, D.; Sahoo, N. K.

    2014-04-24

    Tantalum penta-oxide thin films have been deposited by reactive sputtering technique using asymmetric bipolar pulsed DC source at various oxygen percentage viz. 0 to 50 %. The optical properties of the films have been studied by spectroscopic ellipsometry measurements. It has been observed that compact films with low void fraction, high refractive index and band gap can be obtained by the above technique with oxygen percentage in the range of 30–40%. The films deposited with zero or very low oxygen content have high deposition rate and yield metal rich films with large voids, defects, low band gap and high refractive index. Similarly films deposited with >40% oxygen content again contain voids and defects due to the presence of large amount of gas molecules in the sputtering ambient.

  5. High-Power COIL and YAG Laser Welding

    DTIC Science & Technology

    2002-01-24

    UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADP012387 TITLE: High-Power COIL and YAG Laser Welding DISTRIBUTION...ADP012376 thru ADP012405 UNCLASSIFIED High-power COIL and YAG laser welding Fumio Wani, Tokuhiro Nakabayashi, Akiyoshi Hayakawa, Sachio Suzuki, and...is worse, but it has the function of pulse modulation which the COIL dose not have. As a result of the welding test with the 6 kW Nd:YAG laser, it

  6. High Power MPD Thruster Performance Measurements

    NASA Technical Reports Server (NTRS)

    LaPointe, Michael R.; Strzempkowski, Eugene; Pencil, Eric

    2004-01-01

    High power magnetoplasmadynamic (MPD) thrusters are being developed as cost effective propulsion systems for cargo transport to lunar and Mars bases, crewed missions to Mars and the outer planets, and robotic deep space exploration missions. Electromagnetic MPD thrusters have demonstrated, at the laboratory level, the ability to process megawatts of electrical power while providing significantly higher thrust densities than electrostatic electric propulsion systems. The ability to generate higher thrust densities permits a reduction in the number of thrusters required to perform a given mission, and alleviates the system complexity associated with multiple thruster arrays. The specific impulse of an MPD thruster can be optimized to meet given mission requirements, from a few thousand seconds with heavier gas propellants up to 10,000 seconds with hydrogen propellant. In support of programs envisioned by the NASA Office of Exploration Systems, Glenn Research Center is developing and testing quasi-steady MW-class MPD thrusters as a prelude to steady state high power thruster tests. This paper provides an overview of the GRC high power pulsed thruster test facility, and presents preliminary performance data for a quasi-steady baseline MPD thruster geometry.

  7. CHRONICLE: International forum on advanced high-power lasers and applications (AHPLA '99)

    NASA Astrophysics Data System (ADS)

    Afanas'ev, Yurii V.; Zavestovskaya, I. N.; Zvorykin, V. D.; Ionin, Andrei A.; Senatsky, Yu V.; Starodub, Aleksandr N.

    2000-05-01

    A review of reports made on the International Forum on Advanced High-Power Lasers and Applications, which was held at the beginning of November 1999 in Osaka (Japan), is presented. Five conferences were held during the forum on High-Power Laser Ablation, High-Power Lasers in Energy Engineering, High-Power Lasers in Civil Engineering and Architecture, High-Power Lasers in Manufacturing, and Advanced High-Power Lasers. The following trends in the field of high-power lasers and their applications were presented: laser fusion, laser applications in space, laser-triggered lightning, laser ablation of materials by short and ultrashort pulses, application of high-power lasers in manufacturing, application of high-power lasers in mining, laser decommissioning and decontamination of nuclear reactors, high-power solid-state and gas lasers, x-ray and free-electron lasers. One can find complete information on the forum in SPIE, vols. 3885-3889.

  8. High-power semiconductor lasers at eye-safe wavelengths

    NASA Astrophysics Data System (ADS)

    Osowski, Mark L.; Gewirtz, Yossi; Lammert, Robert M.; Oh, Se W.; Panja, Chameli; Elarde, Victor C.; Vaissie, Laurent; Patel, Falgun D.; Ungar, Jeffrey E.

    2009-05-01

    InP based diode lasers are required to realize the next generation of eyesafe applications, including direct rangefinding and HEL weapons systems. We report on the progress of high power eyesafe single spatial and longitudinal mode 1550nm MOPA devices, where we have achieved peak powers in excess of 10W with 50ns pulse widths. A conceptual model based on our recent MOPA results show the path towards scaling to high powers based on spatial beam combination with operating conditions suitable for direct rangefinding applications. We also report on the progress towards high power 14xx and 15xx nm pump lasers for eyesafe HEL systems.

  9. High Power Helicon Plasma Source for Plasma Processing

    NASA Astrophysics Data System (ADS)

    Prager, James; Ziemba, Timothy; Miller, Kenneth E.

    2015-09-01

    Eagle Harbor Technologies (EHT), Inc. is developing a high power helicon plasma source. The high power nature and pulsed neutral gas make this source unique compared to traditional helicon source. These properties produce a plasma flow along the magnetic field lines, and therefore allow the source to be decoupled from the reaction chamber. Neutral gas can be injected downstream, which allows for precision control of the ion-neutral ratio at the surface of the sample. Although operated at high power, the source has demonstrated very low impurity production. This source has applications to nanoparticle productions, surface modification, and ionized physical vapor deposition.

  10. Hybrid high power femtosecond laser system

    NASA Astrophysics Data System (ADS)

    Trunov, V. I.; Petrov, V. V.; Pestryakov, E. V.; Kirpichnikov, A. V.

    2006-01-01

    Design of a high-power femtosecond laser system based on hybrid chirped pulse amplification (CPA) technique developed by us is presented. The goal of the hybrid principle is the use of the parametric and laser amplification methods in chirped pulse amplifiers. It makes it possible to amplify the low-cycle pulses with a duration of <= fs to terawatt power with a high contrast and high conversion efficiency of the pump radiation. In a created system the Ti:Sapphire laser with 10 fs pulses at 810 nm and output energy about 1-3 nJ will be used like seed source. The oscillator pulses were stretched to duration of about 500 ps by an all-reflective grating stretcher. Then the stretched pulses are injected into a nondegenerate noncollinear optical parametric amplifier (NOPA) on the two BBO crystals. After amplification in NOPA the residual pump was used in a bow-tie four pass amplifier with hybrid active medium (based on Al II0 3:Ti 3+ and BeAl IIO 4:Ti 3+ crystals). The final stage of the amplification system consists of two channels, namely NIR (820 nm) and short-VIS (410 nm). Numerical simulation has shown that the terawatt level of output power can be achieved also in a short-VIS channel at the pumping of the double-crystal BBO NOPA by the radiation of the fourth harmonic of the Nd:YAG laser at 266 nm. Experimentally parametric amplification in BBO crystals of 30-50 fs pulses were investigated and optimized using SPIDER technique and single-shot autocomelator for the realization of shortest duration 40 fs.

  11. High power ferrite microwave switch

    NASA Technical Reports Server (NTRS)

    Bardash, I.; Roschak, N. K.

    1975-01-01

    A high power ferrite microwave switch was developed along with associated electronic driver circuits for operation in a spaceborne high power microwave transmitter in geostationary orbit. Three units were built and tested in a space environment to demonstrate conformance to the required performance characteristics. Each unit consisted of an input magic-tee hybrid, two non-reciprocal latching ferrite phase shifters, an out short-slot 3 db quadrature coupler, a dual driver electronic circuit, and input logic interface circuitry. The basic mode of operation of the high power ferrite microwave switch is identical to that of a four-port, differential phase shift, switchable circulator. By appropriately designing the phase shifters and electronic driver circuits to operate in the flux-transfer magnetization mode, power and temperature insensitive operation was achieved. A list of the realized characteristics of the developed units is given.

  12. On the phase formation of sputtered hafnium oxide and oxynitride films

    SciTech Connect

    Sarakinos, K.; Music, D.; Mraz, S.; Baben, M. to; Jiang, K.; Nahif, F.; Braun, A.; Zilkens, C.; Schneider, J. M.; Konstantinidis, S.; Renaux, F.; Cossement, D.; Munnik, F.

    2010-07-15

    Hafnium oxynitride films are deposited from a Hf target employing direct current magnetron sputtering in an Ar-O{sub 2}-N{sub 2} atmosphere. It is shown that the presence of N{sub 2} allows for the stabilization of the transition zone between the metallic and the compound sputtering mode enabling deposition of films at well defined conditions of target coverage by varying the O{sub 2} partial pressure. Plasma analysis reveals that this experimental strategy facilitates control over the flux of the O{sup -} ions which are generated on the oxidized target surface and accelerated by the negative target potential toward the growing film. An arrangement that enables film growth without O{sup -} ion bombardment is also implemented. Moreover, stabilization of the transition sputtering zone and control of the O{sup -} ion flux without N{sub 2} addition is achieved employing high power pulsed magnetron sputtering. Structural characterization of the deposited films unambiguously proves that the phase formation of hafnium oxide and hafnium oxynitride films with the crystal structure of HfO{sub 2} is independent from the O{sup -} bombardment conditions. Experimental and theoretical data indicate that the presence of vacancies and/or the substitution of O by N atoms in the nonmetal sublattice favor the formation of the cubic and/or the tetragonal HfO{sub 2} crystal structure at the expense of the monoclinic HfO{sub 2} one.

  13. Integrated high power VCSEL systems

    NASA Astrophysics Data System (ADS)

    Moench, Holger; Conrads, Ralf; Gronenborn, Stephan; Gu, Xi; Miller, Michael; Pekarski, Pavel; Pollmann-Retsch, Jens; Pruijmboom, Armand; Weichmann, Ulrich

    2016-03-01

    High power VCSEL systems are a novel laser source used for thermal treatment in industrial manufacturing. These systems will be applied in many applications, which have not used a laser source before. This is enabled by the unique combination of efficiency, compactness and robustness. High power VCSEL system technology encompasses elements far beyond the VCSEL chip itself: i.e. heat sinks, bonding technology and integrated optics. This paper discusses the optimization of these components and processes specifically for building high-power laser systems with VCSEL arrays. New approaches help to eliminate components and process steps and make the system more robust and easier to manufacture. New cooler concepts with integrated electrical and mechanical interfaces have been investigated and offer advantages for high power system design. The bonding process of chips on sub-mounts and coolers has been studied extensively and for a variety of solder materials. High quality of the interfaces as well as good reliability under normal operation and thermal cycling have been realized. A viable alternative to soldering is silver sintering. The very positive results which have been achieved with a variety of technologies indicate the robustness of the VCSEL chips and their suitability for high power systems. Beam shaping micro-optics can be integrated on the VCSEL chip in a wafer scale process by replication of lenses in a polymer layer. The performance of VCSEL arrays with integrated collimation lenses has been positively evaluated and the integrated chips are fully compatible with all further assembly steps. The integrated high power systems make the application even easier and more robust. New examples in laser material processing and pumping of solid state lasers are presented.

  14. High-Power Microwave Switch Employing Electron Beam Triggering

    SciTech Connect

    Hirshfield, Jay L

    2012-09-19

    A high-power active microwave pulse compressor is described that modulates the quality factor Q of the energy storage cavity by a new means involving mode conversion controlled by a triggered electron-beam discharge through a switch cavity. The electron beam is emitted from a diamond-coated molybdenum cathode. This report describes the principle of operation, the design of the switch, the configuration used for the test, and the experimental results. The pulse compressor produced output pulses with 140 - 165 MW peak power, power gain of 16 - 20, and pulse duration of 16 - 20 ns at a frequency of 11.43 GHz.

  15. Picosecond pulses in deep ultraviolet (257.5 nm and 206 nm) and mid-IR produced by a high-power 100 kHz solid-state thin-disk laser

    NASA Astrophysics Data System (ADS)

    Turčičová, Hana; Novák, Ondřej; Smrž, Martin; Miura, Taisuke; Endo, Akira; Mocek, TomáÅ.¡

    2016-04-01

    We report on the generation of picosecond deep ultraviolet pulses at 257.5 nm and 206 nm produced as the fourth and fifth harmonic frequencies of the diode-pumped Yb:YAG thin-disk laser at the fundamental wavelength of 1030 nm. We present a proposal for a picosecond pulse mid-IR source tunable between 2 and 3 μm. The laser at the fundamental wavelength is based on a chirped-pulse amplification of pulses of a sub-ps laser oscillator in a regenerative amplifier with a thin-disk active medium. The diode pumping at the zero phonon line is used. The output beam is close to the fundamental spatial mode and the pulses are characterized by a 100 kHz repetition frequency, less than 4 ps pulse duration and <=1 mJ pulse energy. The fundamental beam is split and the main part is first frequency doubled in an LBO crystal. Subsequently the fourth harmonic frequency (257.5 nm) is produced by frequency doubling of the second harmonic frequency in BBO/CLBO crystals. The remaining part of the fundamental beam is summed with the fourth harmonic beam in the 1ω+4ω quantum reaction in a further CLBO crystal for the fifth harmonic frequency (206 nm) production. The design for the generation of the mid-IR wavelengths is based on the optical parametric generation and amplification. The first stage contains a temperature tuned PPLN, the following amplification stages are based on KTA crystals tuned by angle. Picosecond output pulses tunable between 2 and 3 μm at an average power of 10 W are proposed.

  16. Method and apparatus for tuning high power lasers

    DOEpatents

    Hutchinson, Donald P.; Vandersluis, Kenneth L.

    1977-04-19

    This invention relates to high power gas lasers that are adapted to be tuned to a desired lasing wavelength through the use of a gas cell to lower the gain at a natural lasing wavelength and "seeding" the laser with a beam from a low power laser which is lasing at the desired wavelength. This tuning is accomplished with no loss of power and produces a pulse with an altered pulse shape. It is potentially applicable to all gas lasers.

  17. Overview on the high power excimer laser technology

    NASA Astrophysics Data System (ADS)

    Liu, Jingru

    2013-05-01

    High power excimer laser has essential applications in the fields of high energy density physics, inertial fusion energy and industry owing to its advantages such as short wavelength, high gain, wide bandwidth, energy scalable and repetition operating ability. This overview is aimed at an introduction and evaluation of enormous endeavor of the international high power excimer laser community in the last 30 years. The main technologies of high power excimer laser are reviewed, which include the pumping source technology, angular multiplexing and pulse compressing, beam-smoothing and homogenous irradiation, high efficiency and repetitive operation et al. A high power XeCl laser system developed in NINT of China is described in detail.

  18. High-power microwave attenuator employing slow wave structure

    NASA Astrophysics Data System (ADS)

    Yoshida, Mitsuhiro; Matsumoto, Hiroshi; Shintake, Tsumoru; Nishiyama, Koji; Miura, Sadao

    2012-11-01

    Using present pulsed microwave amplifier, we can obtain RF peak power beyond one hundred MW. However, it is not easy to test such a high-power RF. To overcome this difficulty we developed a high-power microwave attenuator employing a slow wave structure. For example, the output power of RF pulse compressor for present electron linear accelerator reaches a few hundreds MW RF power, but the existing dummy loads can absorb only a few tens MW of RF power. The attenuator we developed has a kind of periodic structure and is made of metal only. We operated this attenuator using a high-power RF source, and found that it could be operated fewer than 50 pps RF output at 40 MW, 2.5 μs or 100 MW, 0.5 μs.

  19. High-power, high-intensity laser propagation and interactions

    SciTech Connect

    Sprangle, Phillip; Hafizi, Bahman

    2014-05-15

    This paper presents overviews of a number of processes and applications associated with high-power, high-intensity lasers, and their interactions. These processes and applications include: free electron lasers, backward Raman amplification, atmospheric propagation of laser pulses, laser driven acceleration, atmospheric lasing, and remote detection of radioactivity. The interrelated physical mechanisms in the various processes are discussed.

  20. Rapid heating of matter using high power lasers

    SciTech Connect

    Bang, Woosuk

    2016-04-08

    This slide presentation describes motivation (uniform and rapid heating of a target, opportunity to study warm dense matter, study of nuclear fusion reactions), rapid heating of matter with intense laser-driven ion beams, visualization of the expanding warm dense gold and diamond, and nuclear fusion experiments using high power lasers (direct heating of deuterium spheres (radius ~ 10nm) with an intense laser pulse.

  1. High power gas laser amplifier

    DOEpatents

    Leland, Wallace T.; Stratton, Thomas F.

    1981-01-01

    A high power output CO.sub.2 gas laser amplifier having a number of sections, each comprising a plurality of annular pumping chambers spaced around the circumference of a vacuum chamber containing a cold cathode, gridded electron gun. The electron beam from the electron gun ionizes the gas lasing medium in the sections. An input laser beam is split into a plurality of annular beams, each passing through the sections comprising one pumping chamber.

  2. High power solid state lasers

    SciTech Connect

    Weber, H.

    1988-01-01

    These proceedings discuss the following subjects: trends in materials processing with laser radiation; slabs and high power systems; glasses and new crystals; solid state lasers at HOYA Corp.; lamps, resonators and transmission; glasses as active materials for high average power solid state lasers; flashlamp pumped GGG-crystals; alexandrite lasers; designing telescope resonators; mode operation of neodymium: YAG lasers; intracavity frequency doubling with KTP crystal and thermal effects in cylinder lasers.

  3. The JLab high power ERL light source

    SciTech Connect

    G.R. Neil; C. Behre; S.V. Benson; M. Bevins; G. Biallas; J. Boyce; J. Coleman; L.A. Dillon-Townes; D. Douglas; H.F. Dylla; R. Evans; A. Grippo; D. Gruber; J. Gubeli; D. Hardy; C. Hernandez-Garcia; K. Jordan; M.J. Kelley; L. Merminga; J. Mammosser; W. Moore; N. Nishimori; E. Pozdeyev; J. Preble; R. Rimmer; Michelle D. Shinn; T. Siggins; C. Tennant; R. Walker; G.P. Williams and S. Zhang

    2005-03-19

    concerning the physics performance, design optimization, and operational limitations of such a first generation high power ERL light source.

  4. The JLab high power ERL light source

    NASA Astrophysics Data System (ADS)

    Neil, G. R.; Behre, C.; Benson, S. V.; Bevins, M.; Biallas, G.; Boyce, J.; Coleman, J.; Dillon-Townes, L. A.; Douglas, D.; Dylla, H. F.; Evans, R.; Grippo, A.; Gruber, D.; Gubeli, J.; Hardy, D.; Hernandez-Garcia, C.; Jordan, K.; Kelley, M. J.; Merminga, L.; Mammosser, J.; Moore, W.; Nishimori, N.; Pozdeyev, E.; Preble, J.; Rimmer, R.; Shinn, M.; Siggins, T.; Tennant, C.; Walker, R.; Williams, G. P.; Zhang, S.

    2006-02-01

    system and discuss some of the discoveries we have made concerning the physics performance, design optimization, and operational limitations of such a first generation high power ERL light source.

  5. High power regenerative laser amplifier

    DOEpatents

    Miller, J.L.; Hackel, L.A.; Dane, C.B.; Zapata, L.E.

    1994-02-08

    A regenerative amplifier design capable of operating at high energy per pulse, for instance, from 20-100 Joules, at moderate repetition rates, for instance from 5-20 Hertz is provided. The laser amplifier comprises a gain medium and source of pump energy coupled with the gain medium; a Pockels cell, which rotates an incident beam in response to application of a control signal; an optical relay system defining a first relay plane near the gain medium and a second relay plane near the rotator; and a plurality of reflectors configured to define an optical path through the gain medium, optical relay and Pockels cell, such that each transit of the optical path includes at least one pass through the gain medium and only one pass through the Pockels cell. An input coupler, and an output coupler are provided, implemented by a single polarizer. A control circuit coupled to the Pockels cell generates the control signal in timed relationship with the input pulse so that the input pulse is captured by the input coupler and proceeds through at least one transit of the optical path, and then the control signal is applied to cause rotation of the pulse to a polarization reflected by the polarizer, after which the captured pulse passes through the gain medium at least once more and is reflected out of the optical path by the polarizer before passing through the rotator again to provide an amplified pulse. 7 figures.

  6. High power regenerative laser amplifier

    DOEpatents

    Miller, John L.; Hackel, Lloyd A.; Dane, Clifford B.; Zapata, Luis E.

    1994-01-01

    A regenerative amplifier design capable of operating at high energy per pulse, for instance, from 20-100 Joules, at moderate repetition rates, for instance from 5-20 Hertz is provided. The laser amplifier comprises a gain medium and source of pump energy coupled with the gain medium; a Pockels cell, which rotates an incident beam in response to application of a control signal; an optical relay system defining a first relay plane near the gain medium and a second relay plane near the rotator; and a plurality of reflectors configured to define an optical path through the gain medium, optical relay and Pockels cell, such that each transit of the optical path includes at least one pass through the gain medium and only one pass through the Pockels cell. An input coupler, and an output coupler are provided, implemented by a single polarizer. A control circuit coupled to the Pockels cell generates the control signal in timed relationship with the input pulse so that the input pulse is captured by the input coupler and proceeds through at least one transit of the optical path, and then the control signal is applied to cause rotation of the pulse to a polarization reflected by the polarizer, after which the captured pulse passes through the gain medium at least once more and is reflected out of the optical path by the polarizer before passing through the rotator again to provide an amplified pulse.

  7. Optical phase conjugation of picosecond pulses at 1.06 mum in Sn(2)P(2)S(6):Te for wavefront correction in high-power Nd-doped amplifier systems.

    PubMed

    Bach, Tobias; Nawata, Kouji; Jazbinsek, Mojca; Omatsu, Takashige; Günter, Peter

    2010-01-04

    We report, for the first time to our knowledge, on picosecondpulse optical phase conjugation using photorefractive Sn(2)P(2)S(6) crystals. For 7.2-ps pulses at 1.06 mum, we have achieved phase-conjugate reflectivities of up to 45% with very fast build-up times, about 15 ms at an intensity of 23 W/cm(2) using Te-doped Sn(2)P(2)S(6). We furthermore demonstrate aberration-free 5 W optical output of 8-ps pulses at 1.06 mum from a side pumped Nd:YVO(4) amplifier using the Sn(2)P(2)S(6)-based phase-conjugate feedback.

  8. 2D numerical modelling of gas temperature in a nanosecond pulsed longitudinal He-SrBr2 discharge excited in a high temperature gas-discharge tube for the high-power strontium laser

    NASA Astrophysics Data System (ADS)

    Chernogorova, T. P.; Temelkov, K. A.; Koleva, N. K.; Vuchkov, N. K.

    2016-05-01

    An active volume scaling in bore and length of a Sr atom laser excited in a nanosecond pulse longitudinal He-SrBr2 discharge is carried out. Considering axial symmetry and uniform power input, a 2D model (r, z) is developed by numerical methods for determination of gas temperature in a new large-volume high-temperature discharge tube with additional incompact ZrO2 insulation in the discharge free zone, in order to find out the optimal thermal mode for achievement of maximal output laser parameters. A 2D model (r, z) of gas temperature is developed by numerical methods for axial symmetry and uniform power input. The model determines gas temperature of nanosecond pulsed longitudinal discharge in helium with small additives of strontium and bromine.

  9. Transient Plasma Photonic Crystals for High-Power Lasers.

    PubMed

    Lehmann, G; Spatschek, K H

    2016-06-03

    A new type of transient photonic crystals for high-power lasers is presented. The crystal is produced by counterpropagating laser beams in plasma. Trapped electrons and electrically forced ions generate a strong density grating. The lifetime of the transient photonic crystal is determined by the ballistic motion of ions. The robustness of the photonic crystal allows one to manipulate high-intensity laser pulses. The scheme of the crystal is analyzed here by 1D Vlasov simulations. Reflection or transmission of high-power laser pulses are predicted by particle-in-cell simulations. It is shown that a transient plasma photonic crystal may act as a tunable mirror for intense laser pulses. Generalizations to 2D and 3D configurations are possible.

  10. Sputtering and ion plating

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The proceedings of a conference on sputtering and ion plating are presented. Subjects discussed are: (1) concepts and applications of ion plating, (2) sputtering for deposition of solid film lubricants, (3) commercial ion plating equipment, (4) industrial potential for ion plating and sputtering, and (5) fundamentals of RF and DC sputtering.

  11. Physics of arcing, and implications to sputter deposition

    SciTech Connect

    Anders, Andre

    2003-12-15

    Arcing is a well-known, unwanted discharge regime observed on the surface of sputtering targets. The discharge voltage breaks down to less than 50 V while the current jumps to elevated levels. Arcing is unwanted because it prevents uniform deposition and creates particulates. The issue of arcing has been dealt with by target surface conditioning and by using modern power supplies that have arc suppression incorporated. With increasing quality requirements in terms of uniformity of coatings, and absence of particulates, especially for electrochromic and other advanced coatings applications, the issue of arcing warrants a closer examination with the goal to find other, physics-based, and hopefully better approaches of arcing prevention. From a physics point of view, the onset of arcing is nothing else than the transition of the discharge to a cathodic arc mode, which is characterized by the ignition of non-stationary arc spots. Arc spots operate by a sequence of microexplosions, enabling explosive electron emission, as opposed to secondary electron emission. Arc spots and their fragments have a size distribution in the micrometer and sub-micrometer range, and a characteristic time distribution that has components shorter than microseconds. Understanding the ignition conditions of arc spots are of central physical interest. Spot ignition is associated with electric field enhancement, which can be of geometric nature (roughness,particles), or chemical nature (e.g. oxide formation) and related local accumulation of surface charge. Therefore, it is clear that these issues are of particular concern when operating with high-density plasmas, such as in high-power pulsed sputtering, and when using reactive sputter gases.

  12. High-power microwave development in Russia

    NASA Astrophysics Data System (ADS)

    Gauthier, Sylvain

    1995-03-01

    This is a survey of Russian research and development in high-power microwave (HPM) sources. It emphasizes those sources of nanoseconds pulse duration time which have potential weapon as well as radar applications. It does not cover the whole range of Russian HPM research and development but concentrates on those aspects which may lead to military applications. Russian investigators have achieved many world firsts in HPM generation; for example, a multiwave Cerenkov generator with a peak output power of 15 gigawatts. Their successes are based on their impressive capability in pulsed power technology which has yielded high-current generators of terawatt peak power. They have transformed the energy of these currents into microwave radiation using tubes of both conventional and novel designs exploiting relativistic electron beams. Recently, the development of high-current mini-accelerators has moved relativistic electron-beam (REB) HPM generation out of the laboratory and enabled the development of deployable military systems with peak powers in the gigawatt range. As a result, they now see development of a REB-based radar systems as one of the most promising directions in radar systems. Details of such a system are described and the implications for HPM weapons are considered.

  13. High power THz sources for nonlinear imaging

    SciTech Connect

    Tekavec, Patrick F.; Kozlov, Vladimir G.

    2014-02-18

    Many biological and chemical compounds have unique absorption features in the THz (0.1 - 10 THz) region, making the use of THz waves attractive for imaging in defense, security, biomedical imaging, and monitoring of industrial processes. Unlike optical radiation, THz frequencies can pass through many substances such as paper, clothing, ceramic, etc. with little attenuation. The use of currently available THz systems is limited by lack of highpower, sources as well as sensitive detectors and detector arrays operating at room temperature. Here we present a novel, high power THz source based on intracavity downconverison of optical pulses. The source delivers 6 ps pulses at 1.5 THz, with an average power of >300 μW and peak powers >450 mW. We propose an imaging method based on frequency upconverison that is ideally suited to use the narrow bandwidth and high peak powers produced by the source. By upconverting the THz image to the infrared, commercially available detectors can be used for real time imaging.

  14. Pulse

    MedlinePlus

    ... the underside of the opposite wrist, below the base of the thumb. Press with flat fingers until ... determine if the patient's heart is pumping. Pulse measurement has other uses as well. During or immediately ...

  15. Magnetron sputtering source

    DOEpatents

    Makowiecki, D.M.; McKernan, M.A.; Grabner, R.F.; Ramsey, P.B.

    1994-08-02

    A magnetron sputtering source for sputtering coating substrates includes a high thermal conductivity electrically insulating ceramic and magnetically attached sputter target which can eliminate vacuum sealing and direct fluid cooling of the cathode assembly. The magnetron sputtering source design results in greater compactness, improved operating characteristics, greater versatility, and low fabrication cost. The design easily retrofits most sputtering apparatuses and provides for safe, easy, and cost effective target replacement, installation, and removal. 12 figs.

  16. Magnetron sputtering source

    DOEpatents

    Makowiecki, Daniel M.; McKernan, Mark A.; Grabner, R. Fred; Ramsey, Philip B.

    1994-01-01

    A magnetron sputtering source for sputtering coating substrates includes a high thermal conductivity electrically insulating ceramic and magnetically attached sputter target which can eliminate vacuum sealing and direct fluid cooling of the cathode assembly. The magnetron sputtering source design results in greater compactness, improved operating characteristics, greater versatility, and low fabrication cost. The design easily retrofits most sputtering apparatuses and provides for safe, easy, and cost effective target replacement, installation, and removal.

  17. Science opportunities at high power accelerators like APT

    SciTech Connect

    Browne, J.C.

    1996-12-31

    This paper presents applications of high power RF proton linear accelerators to several fields. Radioisotope production is an area in which linacs have already provided new isotopes for use in medical and industrial applications. A new type of spallation neutron source, called a long-pulse spallation source (LPSS), is discussed for application to neutron scattering and to the production and use of ultra-cold neutrons (UCN). The concept of an accelerator-driven, transmutation of nuclear waste system, based on high power RF linac technology, is presented along with its impact on spent nuclear fuels.

  18. The role of film interfaces in near-ultraviolet absorption and pulsed-laser damage in ion-beam-sputtered coatings based on HfO2/SiO2 thin-film pairs

    DOE PAGES

    Ristau, Detlev; Papernov, S.; Kozlov, A. A.; ...

    2015-11-23

    The role of thin-film interfaces in the near-ultraviolet absorption and pulsed-laser–induced damage was studied for ion-beam–sputtered and electron-beam–evaporated coatings comprised from HfO2 and SiO2 thin-film pairs. To separate contributions from the bulk of the film and from interfacial areas, absorption and damage-threshold measurements were performed for a one-wave (355-nm wavelength) thick, HfO2 single-layer film and for a film containing seven narrow HfO2 layers separated by SiO2 layers. The seven-layer film was designed to have a total optical thickness of HfO2 layers, equal to one wave at 355 nm and an E-field peak and average intensity similar to a single-layer HfO2more » film. Absorption in both types of films was measured using laser calorimetry and photothermal heterodyne imaging. The results showed a small contribution to total absorption from thin-film interfaces, as compared to HfO2 film material. The relevance of obtained absorption data to coating near-ultraviolet, nanosecond-pulse laser damage was verified by measuring the damage threshold and characterizing damage morphology. The results of this study revealed a higher damage resistance in the seven-layer coating as compared to the single-layer HfO2 film in both sputtered and evaporated coatings. Here, the results are explained through the similarity of interfacial film structure with structure formed during the co-deposition of HfO2 and SiO2 materials.« less

  19. The role of film interfaces in near-ultraviolet absorption and pulsed-laser damage in ion-beam-sputtered coatings based on HfO2/SiO2 thin-film pairs

    SciTech Connect

    Ristau, Detlev; Papernov, S.; Kozlov, A. A.; Oliver, J. B.; Smith, C.; Jensen, L.; Gunster, S.; Madebach, H.

    2015-11-23

    The role of thin-film interfaces in the near-ultraviolet absorption and pulsed-laser–induced damage was studied for ion-beam–sputtered and electron-beam–evaporated coatings comprised from HfO2 and SiO2 thin-film pairs. To separate contributions from the bulk of the film and from interfacial areas, absorption and damage-threshold measurements were performed for a one-wave (355-nm wavelength) thick, HfO2 single-layer film and for a film containing seven narrow HfO2 layers separated by SiO2 layers. The seven-layer film was designed to have a total optical thickness of HfO2 layers, equal to one wave at 355 nm and an E-field peak and average intensity similar to a single-layer HfO2 film. Absorption in both types of films was measured using laser calorimetry and photothermal heterodyne imaging. The results showed a small contribution to total absorption from thin-film interfaces, as compared to HfO2 film material. The relevance of obtained absorption data to coating near-ultraviolet, nanosecond-pulse laser damage was verified by measuring the damage threshold and characterizing damage morphology. The results of this study revealed a higher damage resistance in the seven-layer coating as compared to the single-layer HfO2 film in both sputtered and evaporated coatings. Here, the results are explained through the similarity of interfacial film structure with structure formed during the co-deposition of HfO2 and SiO2 materials.

  20. Propagation of High Power Pulses of 10.6 micrometers Radiation from A CO2 TEA Laser of Novel Design through Clouds Produced by Adiabatic Expansion in the Laboratory

    DTIC Science & Technology

    1976-07-01

    only one side, the other being similar. A magnified section of the reflector mountings is shown above. Scale: j actual size. 16 )4b A)P rI C~j 0 1:1 C)l...infers N rI LI PART C: TRANSMITTANCE, EASUREMENTS Section C1. Attenuation of TEA Laser 1O.6um Pulses k •The system shown in figure 81 has been used to...second photon drag detector D2 directly connected to the second channel of the oscilloscope. The Ge flat RI served also to deflect a 4e-Ne laser beam

  1. Breakdown phenomena in high power klystrons

    SciTech Connect

    Vlieks, A.E.; Allen, M.A.; Callin, R.S.; Fowkes, W.R.; Hoyt, E.W.; Lebacqz, J.V.; Lee, T.G.

    1988-03-01

    In the course of developing new high peak power klystrons at SLAC, high electric fields in several regions of these devices have become an important source of vacuum breakdown phenomena. In addition, a renewed interest in breakdown phenomena for nanosecond pulse, multi-megavolt per centimeter fields has been sparked by recent R and D work in the area of gigawatt RF sources. The most important regions of electrical breakdown are in the output cavity gap area, the RF ceramic windows, and the gun ceramic insulator. The details of the observed breakdown in these regions, experiments performed to understand the phenomena and solutions found to alleviate the problems will be discussed. Recently experiments have been performed on a new prototype R and D klystron. Peak electric fields across the output cavity gaps of this klystron exceed 2 MV/cm. The effect of peak field duration (i.e. pulse width) on the onset of breakdown have been measured. The pulse widths varied from tens of nanoseconds to microseconds. Results from these experiments will be presented. The failure of ceramic RF windows due to multipactor and puncturing was an important problem to overcome in order that our high power klystrons would have a useful life expectancy. Consequently many studies and tests were made to understand and alleviate window breakdown phenomena. Some of the results in this area, especially the effects of surface coatings, window materials and processing techniques and their effects on breakdown will be discussed. Another important source of klystron failure in the recent past at SLAC has been the puncturing of the high voltage ceramic insulator in the gun region. A way of alleviating this problem has been found although the actual cause of the puncturing is not yet clear. The ''practical'' solution to this breakdown process will be described and a possible mechanism for the puncturing will be presented. 9 refs., 5 figs., 3 tabs.

  2. Formation of dielectric silicon compounds by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Veselov, D. S.; Voronov, Yu A.

    2016-09-01

    The paper is devoted to the study of reactive magnetron sputtering of the silicon target in the ambient of inert argon gas with reactive gas, nitrogen or oxygen. The magnetron was powered by two mid-frequency generators of a rectangular pulse of opposite polarity. The negative polarity pulse provides the sputtering of the target. The positive polarity pulse provides removal of accumulated charge from the surface of the target. This method does not require any special devices of resistances matching and provides continuous sputtering of the target.

  3. High power cladding light strippers

    NASA Astrophysics Data System (ADS)

    Wetter, Alexandre; Faucher, Mathieu; Sévigny, Benoit

    2008-02-01

    The ability to strip cladding light from double clad fiber (DCF) fibers is required for many different reasons, one example is to strip unwanted cladding light in fiber lasers and amplifiers. When removing residual pump light for example, this light is characterized by a large numerical aperture distribution and can reach power levels into the hundreds of watts. By locally changing the numerical aperture (N.A.) of the light to be stripped, it is possible to achieve significant attenuation even for the low N.A. rays such as escaped core modes in the same device. In order to test the power-handling capability of this device, one hundred watts of pump and signal light is launched from a tapered fusedbundle (TFB) 6+1x1 combiner into a high power-cladding stripper. In this case, the fiber used in the cladding stripper and the output fiber of the TFB was a 20/400 0.06/0.46 N.A. double clad fiber. Attenuation of over 20dB in the cladding was measured without signal loss. By spreading out the heat load generated by the unwanted light that is stripped, the package remained safely below the maximum operating temperature internally and externally. This is achieved by uniformly stripping the energy along the length of the fiber within the stripper. Different adhesive and heat sinking techniques are used to achieve this uniform removal of the light. This suggests that these cladding strippers can be used to strip hundreds of watts of light in high power fiber lasers and amplifiers.

  4. MULTIPULSE - high resolution and high power in one TDEM system

    NASA Astrophysics Data System (ADS)

    Chen, Tianyou; Hodges, Greg; Miles, Philip

    2015-09-01

    An airborne time domain electromagnetic (TEM) system with high resolution and great depth of exploration is desired for geological mapping as well as for mineral exploration. The MULTIPULSE technology enables an airborne TEM system to transmit a high power pulse (a half-sine, for instance) and one or multiple low power pulse(s) (trapezoid or square) within a half-cycle. The high power pulse ensures good depth of exploration and the low power pulse allows a fast transmitter current turn off and earlier off-time measurement thus providing higher frequency signals, which allows higher near-surface resolution and better sensitivity to weak conductors. The power spectrum of the MULTIPULSE waveform comprising a half-sine and a trapezoid pulse clearly shows increased power in the higher frequency range (> ~2.3 kHz) compared to that of a single half-sine waveform. The addition of the low power trapezoid pulse extends the range of the sensitivity 10-fold towards the weak conductors, expanding the geological conductivity range of a system and increasing the scope of its applications. The MULTIPULSE technology can be applied to standard single-pulse airborne TEM systems on both helicopter and fixed-wing. We field tested the HELITEM MULTIPULSE system over a wire-loop in Iroquois Falls, demonstrating the different sensitivity of the high and low power pulses to the overburden and the wire-loop. We also tested both HELITEM and GEOTEM MULTIPULSE systems over a layered oil sand geologic setting in Fort McMurray, Alberta, Canada. The results show comparable shallow geologic resolution of the MULTIPULSE to that of the RESOLVE system while maintaining superior depth of exploration, confirming the increased geological conductivity range of a system employing MULTIPULSE compared to the standard single-pulse systems.

  5. The future of high power laser techniques

    NASA Astrophysics Data System (ADS)

    Poprawe, Reinhart; Loosen, Peter; Hoffmann, Hans-Dieter

    2007-05-01

    High Power Lasers have been used for years in corresponding applications. Constantly new areas and new processes have been demonstrated, developed and transferred to fruitful use in industry. With the advent of diode pumped solid state lasers in the multi-kW-power regime at beam qualities not far away from the diffraction limit, a new area of applicability has opened. In welding applications speeds could be increased and systems could be developed with higher efficiently leading also to new perspectives for increased productivity, e.g. in combined processing. Quality control is increasingly demanded by the applying industries, however applications still are rare. Higher resolution of coaxial process control systems in time and space combined with new strategies in signal processing could give rise to new applications. The general approach described in this paper emphasizes the fact, that laser applications can be developed more efficiently, more precisely and with higher quality, if the laser radiation is tailored properly to the corresponding application. In applying laser sources, the parameter ranges applicable are by far wider and more flexible compared to heat, mechanical or even electrical energy. The time frame ranges from several fs to continuous wave and this spans approximately 15 orders of magnitude. Spacewise, the foci range from several µm to cm and the resulting intensities suitable for materials processing span eight orders of magnitude from 10 3 to 10 11 W/cm2. In addition to space (power, intensity) and time (pulse) the wavelength can be chosen as a further parameter of optimization. As a consequence, the resulting new applications are vast and can be utilized in almost every market segment of our global economy (Fig. 1). In the past and only partly today, however, this flexibility of laser technology is not exploited in full in materials processing, basically because in the high power regime the lasers with tailored beam properties are not

  6. Optics assembly for high power laser tools

    DOEpatents

    Fraze, Jason D.; Faircloth, Brian O.; Zediker, Mark S.

    2016-06-07

    There is provided a high power laser rotational optical assembly for use with, or in high power laser tools for performing high power laser operations. In particular, the optical assembly finds applications in performing high power laser operations on, and in, remote and difficult to access locations. The optical assembly has rotational seals and bearing configurations to avoid contamination of the laser beam path and optics.

  7. Heavy particle transport in sputtering systems

    NASA Astrophysics Data System (ADS)

    Trieschmann, Jan

    2015-09-01

    This contribution aims to discuss the theoretical background of heavy particle transport in plasma sputtering systems such as direct current magnetron sputtering (dcMS), high power impulse magnetron sputtering (HiPIMS), or multi frequency capacitively coupled plasmas (MFCCP). Due to inherently low process pressures below one Pa only kinetic simulation models are suitable. In this work a model appropriate for the description of the transport of film forming particles sputtered of a target material has been devised within the frame of the OpenFOAM software (specifically dsmcFoam). The three dimensional model comprises of ejection of sputtered particles into the reactor chamber, their collisional transport through the volume, as well as deposition of the latter onto the surrounding surfaces (i.e. substrates, walls). An angular dependent Thompson energy distribution fitted to results from Monte-Carlo simulations is assumed initially. Binary collisions are treated via the M1 collision model, a modified variable hard sphere (VHS) model. The dynamics of sputtered and background gas species can be resolved self-consistently following the direct simulation Monte-Carlo (DSMC) approach or, whenever possible, simplified based on the test particle method (TPM) with the assumption of a constant, non-stationary background at a given temperature. At the example of an MFCCP research reactor the transport of sputtered aluminum is specifically discussed. For the peculiar configuration and under typical process conditions with argon as process gas the transport of aluminum sputtered of a circular target is shown to be governed by a one dimensional interaction of the imposed and backscattered particle fluxes. The results are analyzed and discussed on the basis of the obtained velocity distribution functions (VDF). This work is supported by the German Research Foundation (DFG) in the frame of the Collaborative Research Centre TRR 87.

  8. A Preliminary In Vitro Study on the Efficacy of High-Power Photodynamic Therapy (HLLT): Comparison between Pulsed Diode Lasers and Superpulsed Diode Lasers and Impact of Hydrogen Peroxide with Controlled Stabilization.

    PubMed

    Caccianiga, Gianluigi; Baldoni, Marco; Ghisalberti, Carlo Angelo; Paiusco, Alessio

    2016-01-01

    Aim. In periodontology lasers have been suggested for the photodynamic therapy (PDT): such therapy can be defined as the inactivation of cells, microorganisms, or molecules induced by light and not by heat. The aim of this study was to evaluate results of PDT using a 980 nm diode laser (Wiser Doctor Smile, Lambda SPA, Italy) combined with hydrogen peroxide, comparing a pulsed diode laser (LI) activity to a high-frequency superpulsed diode laser (LII). Materials and Methods. Primary fibroblasts and keratinocytes cell lines, isolated from human dermis, were irradiated every 48 h for 10 days using LI and LII combined with SiOxyL(+) ™ Solution (hydrogen peroxide (HP) stabilized with a glycerol phosphate complex). Two days after the last irradiation, the treated cultures were analyzed by flow cytofluorometry (FACS) and western blotting to quantify keratin 5 and keratin 8 with monoclonal antibodies reactive to cytokeratin 5 and cytokeratin 8. Antimicrobial activity was also evaluated. Results. Both experimental models show the superiority of LII against LI. In parallel, stabilized HP provided better results in the regeneration test in respect to common HP, while the biocidal activity remains comparable. Conclusion. The use of high-frequency lasers combined with stabilized hydrogen peroxide can provide optimal results for a substantial decrease of bacterial count combined with a maximal biostimulation induction of soft tissues and osteogenesis.

  9. A Preliminary In Vitro Study on the Efficacy of High-Power Photodynamic Therapy (HLLT): Comparison between Pulsed Diode Lasers and Superpulsed Diode Lasers and Impact of Hydrogen Peroxide with Controlled Stabilization

    PubMed Central

    Baldoni, Marco; Ghisalberti, Carlo Angelo; Paiusco, Alessio

    2016-01-01

    Aim. In periodontology lasers have been suggested for the photodynamic therapy (PDT): such therapy can be defined as the inactivation of cells, microorganisms, or molecules induced by light and not by heat. The aim of this study was to evaluate results of PDT using a 980 nm diode laser (Wiser Doctor Smile, Lambda SPA, Italy) combined with hydrogen peroxide, comparing a pulsed diode laser (LI) activity to a high-frequency superpulsed diode laser (LII). Materials and Methods. Primary fibroblasts and keratinocytes cell lines, isolated from human dermis, were irradiated every 48 h for 10 days using LI and LII combined with SiOxyL+™ Solution (hydrogen peroxide (HP) stabilized with a glycerol phosphate complex). Two days after the last irradiation, the treated cultures were analyzed by flow cytofluorometry (FACS) and western blotting to quantify keratin 5 and keratin 8 with monoclonal antibodies reactive to cytokeratin 5 and cytokeratin 8. Antimicrobial activity was also evaluated. Results. Both experimental models show the superiority of LII against LI. In parallel, stabilized HP provided better results in the regeneration test in respect to common HP, while the biocidal activity remains comparable. Conclusion. The use of high-frequency lasers combined with stabilized hydrogen peroxide can provide optimal results for a substantial decrease of bacterial count combined with a maximal biostimulation induction of soft tissues and osteogenesis. PMID:27631000

  10. Internal electron conversion of the isomeric {sup 57}Fe nucleus state with an energy of 14.4 keV excited by the radiation of the plasma of a high-power femtosecond laser pulse

    SciTech Connect

    Golovin, G V; Savel'ev-Trofimov, Andrei B; Uryupina, D S; Volkov, Roman V

    2011-03-31

    We recorded the spectrum of delayed secondary electrons ejected from the target, which was coated with a layer of iron enriched with the {sup 57}Fe isotope to 98%, under its irradiation by fluxes of broadband X-ray radiation and fast electrons from the plasma produced by a femtosecond laser pulse at an intensity of 10{sup 17} W cm{sup -2}. Maxima were identified at energies of 5.6, 7.2, and 13.6 keV in the spectrum obtained for a delay of 90 - 120 ns. The two last-listed maxima owe their origin to the internal electron conversion of the isomeric level with an energy of 14.4 keV and a lifetime of 98 ns to the K and L shells of atomic iron, respectively; the first-named level arises from a cascade K - L{sub 2}L{sub 3} Auger process. Photoexcitaion by the X-ray plasma radiation is shown to be the principal channel of the isomeric level excitation. (interaction of laser radiation with matter)

  11. High Power Helicon Propulsion Experiments

    NASA Astrophysics Data System (ADS)

    Ziemba, Timothy; Slough, John; Winglee, Robert

    2005-02-01

    The High Power Helicon (HPH) under development at the University of Washington may have an attractive application as an electrode-less in-space thruster. Output plasma characteristics show that plasma is created in and near the helicon coil and is accelerated by a helicon induced axial potential downstream away from the HPH. The bulk acceleration of the plasma is believed to be due to a coupling of the plasma electrons to the helicon field, which in turn transfers energy to the ions via an ambipolar electric field. Downstream electric potentials of greater than 150 volts having been measured with the amplitude of the electric field being dependent on experimentally controlled parameters. Time of flight measurements of the plasma transiting downstream show specific impulses (Isp) near 2000 seconds for Argon with calculated thrust levels near 1 Newton for input powers to the plasma in the tens of kilowatts. The system is capable of using different neutral gases as propellants with nitrogen and hydrogen having baseline Isp levels of 3000 and 5000 seconds respectfully giving some variability in Isp and thrust by the choice of propellants. Current work focuses on the determination and optimization of the system efficiencies and increasing output power levels.

  12. High-Power Rf Load

    DOEpatents

    Tantawi, Sami G.; Vlieks, Arnold E.

    1998-09-01

    A compact high-power RF load comprises a series of very low Q resonators, or chokes [16], in a circular waveguide [10]. The sequence of chokes absorb the RF power gradually in a short distance while keeping the bandwidth relatively wide. A polarizer [12] at the input end of the load is provided to convert incoming TE.sub.10 mode signals to circularly polarized TE.sub.11 mode signals. Because the load operates in the circularly polarized mode, the energy is uniformly and efficiently absorbed and the load is more compact than a rectangular load. Using these techniques, a load having a bandwidth of 500 MHz can be produced with an average power dissipation level of 1.5 kW at X-band, and a peak power dissipation of 100 MW. The load can be made from common lossy materials, such as stainless steel, and is less than 15 cm in length. These techniques can also produce loads for use as an alternative to ordinary waveguide loads in small and medium RF accelerators, in radar systems, and in other microwave applications. The design is easily scalable to other RF frequencies and adaptable to the use of other lossy materials.

  13. HIGH POWER BEAM DUMP AND TARGET / ACCELERATOR INTERFACE PROCEDURES

    SciTech Connect

    Blokland, Willem; Plum, Michael A; Peters, Charles C; Brown, David L; Galambos, John D

    2013-01-01

    Satisfying operational procedures and limits for the beam target interface is a critical concern for high power operation at spallation neutron sources. At the Oak Ridge Spallation Neutron Source (SNS) a number of protective measures are instituted to ensure that the beam position, beam size and peak intensity are within acceptable limits at the target and high power Ring Injection Dump (RID). The high power beam dump typically handles up to 50 100 kW of beam power and its setup is complicated by the fact that there are two separate beam components simultaneously directed to the dump. The beam on target is typically in the 800-1000 kW average power level, delivered in sub- s 60 Hz pulses. Setup techniques using beam measurements to quantify the beam parameters at the target and dump will be described. However, not all the instrumentation used for the setup and initial qualification is available during high power operation. Additional techniques are used to monitor the beam during high power operation to ensure the setup conditions are maintained, and these are also described.

  14. High-power MUTC photodetectors for RF photonic links

    NASA Astrophysics Data System (ADS)

    Estrella, Steven; Johansson, Leif A.; Mashanovitch, Milan L.; Beling, Andreas

    2016-02-01

    High power photodiodes are needed for a range of applications. The high available power conversion efficiency makes these ideal for antenna remoting applications, including high power, low duty-cycle RF pulse generation. The compact footprint and fiber optic input allow densely packed RF aperture arrays with low cross-talk for phased high directionality emitters. Other applications include linear RF photonic links and other high dynamic range optical systems. Freedom Photonics has developed packaged modified uni-traveling carrier (MUTC) photodetectors for high-power applications. Both single and balanced photodetector pairs are mounted on a ceramic carrier, and packaged in a compact module optimized for high power operation. Representative results include greater than 100 mA photocurrent, >100m W generated RF power and >20 GHz bandwidth. In this paper, we evaluate the saturation and bandwidth of these single ended and balanced photodetectors for detector diameter in the 16 μm to 34 μm range. Packaged performance is compared to chip performance. Further new development towards the realization of <100GHz packaged photodetector modules with optimized high power performance is described. Finally, incorporation of these photodetector structures in novel photonic integrated circuits (PICs) for high optical power application areas is outlined.

  15. Pulsed power

    NASA Astrophysics Data System (ADS)

    Stone, David H.

    Pulsed power systems are critical elements for such prospective weapons technologies as high-power microwaves, electrothermal and electromagnetic projectile launchers, neutral particle beams, space-based FELs, ground-based lasers, and charged particle beams. Pulsed power will also be essential for the development of nonweapon military systems such as lidars and ultrawideband radars, and could serve as the bases for nuclear weapon effect simulators. The pulsed power generation requirements for each of these systems is considered.

  16. Transmission grating stretcher for contrast enhancement of high power lasers.

    PubMed

    Tang, Yunxin; Hooker, Chris; Chekhlov, Oleg; Hawkes, Steve; Collier, John; Rajeev, P P

    2014-12-01

    We propose, for the first time, a transmission grating stretcher for high power lasers and demonstrate its superiority over conventional, reflective gold grating stretchers in terms of pulse temporal quality. We show that, compared to a conventional stretcher with the same stretching factor, the transmission-grating based stretcher yields more than an order of magnitude improvement in the contrast pedestal. We have also quantitatively characterized the roughness of the grating surfaces and estimated its impact on the contrast pedestal.

  17. High power operational experience with the LANSCE Linac

    SciTech Connect

    Rybarcyk, Lawrence J

    2008-01-01

    The heart of the Los Alamos Neutron Science Center (LANSCE) is a pulsed linear accelerator that is used to simultaneously provide H+ and H- beams to several user facilities. This accelerator contains two Cockcroft-Walton style injectors, a 100-MeV drift tube linac and an 800-MeV coupled cavity linac. This presentation will touch on various aspects of the high power operation including performance, tune-up strategy, beam losses and machine protection.

  18. Beam breakup integral measurement on high-power laser chains.

    PubMed

    Villate, Denis; Blanchot, Nathalie; Rouyer, Claude

    2007-03-01

    We experimentally demonstrate the efficiency of a single-shot method to measure the beam breakup integral (B) accumulated across a high power chain. The technique uses spectrally shaped strongly chirped femtosecond pulses and takes advantage of time-to-spectral coupling generated by nonlinear effects. We performed B measurements on regenerative amplifiers (Ti:sapphire) and on the ALISE 200 J facility currently installed at CEA-CESTA (France).

  19. High-power synchronously pumped femtosecond Raman fiber laser.

    PubMed

    Churin, D; Olson, J; Norwood, R A; Peyghambarian, N; Kieu, K

    2015-06-01

    We report a high-power synchronously pumped femtosecond Raman fiber laser operating in the normal dispersion regime. The Raman laser is pumped by a picosecond Yb(3+)-doped fiber laser. It produces highly chirped pulses with energy up to 18 nJ, average power of 0.76 W and 88% efficiency. The pulse duration is measured to be 147 fs after external compression. We observed two different regimes of operation of the laser: coherent and noise-like regime. Both regimes were experimentally characterized. Numerical simulations are in a good agreement with experimental results.

  20. Neutron testing of high-power optical fibers

    NASA Astrophysics Data System (ADS)

    Cheeseman, M.; Bowden, M.; Akinci, A.; Knowles, S.; Webb, L.

    2012-11-01

    A selection of commercially available high-power optical fibres have been characterised for radiation susceptibility in Sandia's Annular Core Research Reactor (ACRR). The fibres were subjected to a total gamma and neutron dose >2 Mrad(Si) in a 7 ms pulse. The neutron fluence was >1015 n/cm2. Changes in the transmission characteristics of optical fibres carrying high energy, short duration laser pulses (power densities of around 1.5 GW/cm2) were measured. All fibres survived at least two consecutive radiation exposures, showing typical transient transmission losses of around 20%. Post radiation exposure, the transmission characteristics returned to those of pristine fibres within one minute.

  1. High Power Free Electron Lasers

    SciTech Connect

    George Neil

    2004-04-12

    FEL Oscillators have been around since 1977 providing not only a test bed for the physics of Free Electron Lasers and electron/photon interactions but as a workhorse of scientific research. The characteristics that have driven the development of these sources are the desire for high peak and average power, high pulse energies, wavelength tunability, timing flexibility, and wavelengths that are unavailable from more conventional laser sources. User programs have been performed using such sources encompassing medicine, biology, solid state research, atomic and molecular physics, effects of non-linear fields, surface science, polymer science, pulsed laser vapor deposition, to name just a few. Recently the incorporation of energy recovery systems has permitted extension of the average power capabilities to the kW level and beyond. Development of substantially higher power systems with applications in defense and security is believed feasible with modest R&D efforts applied to a few technology areas. This paper will discuss at a summary level the physics of such devices, survey existing and planned facilities, and touch on the applications that have driven the development of these popular light sources.

  2. High power solid state switches

    NASA Astrophysics Data System (ADS)

    Gundersen, Martin

    1991-11-01

    We have successfully produced an optically triggered thyristor based in Gallium Arsenide, developed a model for breakdown, and are developing two related devices, including a Gallium Arsenide based static inductor thyristor. We are getting at the basic limitations of Gallium Arsenide for these applications, and are developing models for the physical processes that will determine device limitations. The previously supported gas phase work - resulting in the back-lighted thyratron (BLT) - has actually resulted in a very changed view of how switching can be accomplished, and this is impacting the design of important machines. The BLT is being studied internationally: in Japan for laser fusion and laser isotope separation. ITT has built a BLT that has switched 30 kA at 60 kV in testing at NSWC Dahlgren and the device is being commercialized by another American company. Versions of the switch are now being tested for excimer laser and other applications. Basically, the switch, which arose from pulse power physics studies at USC, can switch more current faster (higher di/dt), with less housekeeping, and with other advantageous properties. There are a large number of other new applications, include kinetic energy weapons, pulsed microwave sources and R.F. accelerators.

  3. High power, high beam quality regenerative amplifier

    DOEpatents

    Hackel, Lloyd A.; Dane, Clifford B.

    1993-01-01

    A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

  4. High power, high beam quality regenerative amplifier

    DOEpatents

    Hackel, L.A.; Dane, C.B.

    1993-08-24

    A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.

  5. Multitarget sequential sputtering apparatus

    NASA Technical Reports Server (NTRS)

    Shima, R. (Inventor)

    1975-01-01

    The development and characteristics of a sputtering apparatus are discussed. A potential difference is applied between the cathode and anode to produce a plasma for each target which is sputtered by accelerated ions within the plasma. The process of sputtering for various materials is described. Diagrams of the unit are provided.

  6. Extremely high-power CO2 laser beam correction.

    PubMed

    Kudryashov, Alexis; Alexandrov, Alexander; Rukosuev, Alexey; Samarkin, Vadim; Galarneau, Pierre; Turbide, Simon; Châteauneuf, François

    2015-05-10

    This paper presents the results of high-power CO2 laser-aberration correction and jitter stabilization. A bimorph deformable mirror and two tip-tilt piezo correctors were used as executive elements. Two types of wavefront sensors, one Hartmann to measure higher-order aberrations (defocus, astigmatism etc.) based on an uncooled microbolometer long-wave infrared camera and the other a tip-tilt one based on the technology of obliquely sputtered, thin chromium films on Si substrates, were applied to measure wavefront aberrations. We discuss both positive and negative attributes of suggested wavefront sensors. The adaptive system is allowed to reduce aberrations of incoming laser radiation by seven times peak-to-valley and to stabilize the jitter of incoming beams up to 25 μrad at a speed of 100 Hz. The adaptive system frequency range for high-order aberration correction was 50 Hz.

  7. High power microwave switching utilizing a waveguide spark gap.

    PubMed

    Foster, J; Edmiston, G; Thomas, M; Neuber, A

    2008-11-01

    A reduction in the rise time of a 2.85 GHz high power microwave (HPM) pulse is achieved by implementing an overvoltaged spark gap inside a waveguide structure. The spark gap is oriented such that when triggered, the major electric field component of the dominant TE(10) mode is shorted. The transition from a transmissive to a highly reflective microwave structure in a relatively short period of time (tens of nanoseconds) creates a means to switch multimegawatt power levels on a much faster timescale than mechanical switches. An experimental arrangement composed of the waveguide spark gap and a high power circulator is used to reduce the effective rise time of a HPM pulse from a U.S. Air Force AW/PFS-6 radar set from 600 ns down to 50 ns. The resulting HPM pulse exhibits a much more desirable excitation profile when investigating microwave induced dielectric window flashover. Since most theoretical discussions on microwave breakdown assume an ideal step excitation, achieving a "squarelike" pulse is needed if substantial comparison between experiment and theory is sought. An overview of the experimental setup is given along with relevant performance data and comparison with computer modeling of the structure.

  8. The Jefferson Lab High Power Light Source

    SciTech Connect

    James R. Boyce

    2006-01-01

    Jefferson Lab has designed, built and operated two high average power free-electron lasers (FEL) using superconducting RF (SRF) technology and energy recovery techniques. Between 1999-2001 Jefferson Lab operated the IR Demo FEL. This device produced over 2 kW in the mid-infrared, in addition to producing world record average powers in the visible (50 W), ultraviolet (10 W) and terahertz range (50 W) for tunable, short-pulse (< ps) light. This FEL was the first high power demonstration of an accelerator configuration that is being exploited for a number of new accelerator-driven light source facilities that are currently under design or construction. The driver accelerator for the IR Demo FEL uses an Energy Recovered Linac (ERL) configuration that improves the energy efficiency and lowers both the capital and operating cost of such devices by recovering most of the power in the spent electron beam after optical power is extracted from the beam. The IR Demo FEL was de-commissioned in late 2001 for an upgraded FEL for extending the IR power to over 10 kW and the ultraviolet power to over 1 kW. The FEL Upgrade achieved 10 kW of average power in the mid-IR (6 microns) in July of 2004, and its IR operation currently is being extended down to 1 micron. In addition, we have demonstrated the capability of on/off cycling and recovering over a megawatt of electron beam power without diminishing machine performance. A complementary UV FEL will come on-line within the next year. This paper presents a summary of the FEL characteristics, user community accomplishments with the IR Demo, and planned user experiments.

  9. High power laser perforating tools and systems

    SciTech Connect

    Zediker, Mark S; Rinzler, Charles C; Faircloth, Brian O; Koblick, Yeshaya; Moxley, Joel F

    2014-04-22

    ystems devices and methods for the transmission of 1 kW or more of laser energy deep into the earth and for the suppression of associated nonlinear phenomena. Systems, devices and methods for the laser perforation of a borehole in the earth. These systems can deliver high power laser energy down a deep borehole, while maintaining the high power to perforate such boreholes.

  10. Very High Power THz Radiation Sources.

    PubMed

    Carr, G L; Martin, M C; McKinney, W R; Jordan, K; Neil, G R; Williams, G P

    2003-06-01

    We report the production of high power (20watts average, ∼ 1 Megawatt peak) broadbandTHz light based on coherent emission fromrelativistic electrons. Such sources areideal for imaging, for high power damagestudies and for studies of non-linearphenomena in this spectral range. Wedescribe the source, presenting theoreticalcalculations and their experimentalverification. For clarity we compare thissource with one based on ultrafast lasertechniques.

  11. Photoconductive switching for high power microwave generation

    SciTech Connect

    Pocha, M.D.; Hofer, W.W.

    1990-10-01

    Photoconductive switching is a technology that is being increasingly applied to generation of high power microwaves. Two primary semiconductors used for these devices are silicon and gallium arsenide. Diamond is a promising future candidate material. This paper discusses the important material parameters and switching modes, critical issues for microwave generation, and future directions for this high power, photoconductive switching technology.

  12. High Power Electromagnetic (HPEM) Threat Analysis

    DTIC Science & Technology

    2008-04-01

    EMERGING THREATS ...... 13 HEMP coupling characteristics ............................................................................... 13 High power...microwave (HPEM) coupling characteristics ..................................... 16 High power microwave: local protective measures...ncy (W1 Figure 22. Various bands summarizing EM threats. HEMP coupling characteristics In the early 1960’s, researchers proposed a theory that a high

  13. Laboratory Astrophysics on High Power Lasers and Pulsed Power Facilities

    SciTech Connect

    Remington, B A

    2002-02-05

    Over the past decade a new genre of laboratory astrophysics has emerged, made possible by the new high energy density (HED) experimental facilities, such as large lasers, z-pinch generators, and high current particle accelerators. (Remington, 1999; 2000; Drake, 1998; Takabe, 2001) On these facilities, macroscopic collections of matter can be created in astrophysically relevant conditions, and its collective properties measured. Examples of processes and issues that can be experimentally addressed include compressible hydrodynamic mixing, strong shock phenomena, radiative shocks, radiation flow, high Mach-number jets, complex opacities, photoionized plasmas, equations of state of highly compressed matter, and relativistic plasmas. These processes are relevant to a wide range of astrophysical phenomena, such as supernovae and supernova remnants, astrophysical jets, radiatively driven molecular clouds, accreting black holes, planetary interiors, and gamma-ray bursts. These phenomena will be discussed in the context of laboratory astrophysics experiments possible on existing and future HED facilities.

  14. Reliability of High-Power Pulsed IMPATT Diodes.

    DTIC Science & Technology

    1981-11-01

    under test are nour.ted in a water cooled plate and contacted by beryllium - copper fingers. Device case temperature is controlled by varying coolant...beyond the inner mesa radius on one device (see Figure 3-11) indicated the presence of platinum. Possibly a platinum silicide metallization system was

  15. High-powered pulsed-ion-beam acceleration and transport

    SciTech Connect

    Humphries, S. Jr.; Lockner, T.R.

    1981-11-01

    The state of research on intense ion beam acceleration and transport is reviewed. The limitations imposed on ion beam transport by space charge effects and methods available for neutralization are summarized. The general problem of ion beam neutralization in regions free of applied electric fields is treated. The physics of acceleration gaps is described. Finally, experiments on multi-stage ion acceleration are summarized.

  16. Short Pulse Switches for Airborne High Power Supplies

    DTIC Science & Technology

    1973-10-01

    high voltage direct current interrupter tube is patterned after interrupters built by Hughes for HVDC circuit breaker service. These tubes have been...tested at the 100 kV, 2 kA, 2 kV/fisec level. This tube is the only known component inherently capable of HVDC interruption (i. e. , without...GE No. ZR 7512). The pulser circuit is shown in Fig. 11-26. The battery represents the (3 kV) HVDC supply. The total stored energy is

  17. Short Pulse Switches for Airborne High Power Supplies

    DTIC Science & Technology

    1973-10-01

    must be small and lightweight and must operate reliably for 50.000 cycles. All of these design goals can be met utilizing the vacuum interrupter... reliability and to significantly reduce development and future manufacturing costs. Where necessary, modifications have been made to these components in...Westlnghouse proprietary material utilized In our current vacuum Interrupter product line. In order to Insure highly reliable lightweight actuation of

  18. High-power optics and its new manifestations

    NASA Astrophysics Data System (ADS)

    Apollonov, Victor V.

    2013-06-01

    The advent of the laser has placed stringent requirements on the fabrication, performance and quality of optical elements employed within systems for most practical applications. Their high-power performance is generally governed by three distinct steps, firstly the absorption of incident optical radiation (governed primarily by various absorption mechanisms); secondly, followed by a temperature increase and response governed primarily by thermal properties and finally the element’s thermo-optical and thermomechanical response, e.g., distortion, stress, birefringenous fracture, etc. All of which needs to be understood in the design of efficient, compact, reliable and versatile high-power systems, under a variety of operating conditions such as pulsed, continuous wave, rep-rated or burst mode of varying duty cycles. The paper is dedicated to the memory of A M Prokhorov and A H Guenther.

  19. Damage behavior of Nd:glass of high-power disk amplifier medium in ICF Facility

    NASA Astrophysics Data System (ADS)

    He, Shaobo; Chen, Lin; Yuan, Xiaodong; Chen, Yuanbin; Cheng, Xiaofeng; Xie, Xudong; Wang, Wenyi; Zu, Xiaotao

    2016-12-01

    Large aperture Nd:glass disk is often used as the amplifier medium in the inertial confinement fusion (ICF) facilities. The typical size of Nd:glass is up to 810mm×460mm×40mm and more than 3,000 Nd:glass components are needed in the ICF facility. At present, the 3ω fused silica glass and DKDP crystal are mainly responsible for the damage of driver used for ICF. However, with the enlargement of the facility and increase of laser shot number, the laser damage of Nd:glass at 1ω waveband is still an important problem to limit the stable operation of facility and improvement of laser beam quality. In this work, the influence of Nd:glass material itself, mechanical processing, service environment, and laser beam quality on its damage behavior is investigated experimentally and theoretically. The results and conclusions can be summarized as follows: (1) It is very important to control the concentration of platinum impurity particles during melting and the sputtering effect of the cladding materials. (2) The number and length of fractural and brittle scratches should be strictly suppressed during mechanical processing of Nd:glass. (3) The B-integral of high power laser beam should be rigorously controlled. Particularly, the top shape of pulses must be well controlled when operating at high peak laser power. (4) The service environment should be well managed to make sure the cleanness of the surface of Nd:glass better than 100/A level during mounting and running. (5) The service environment and beam quality should be monitored during operation.

  20. Ion beam sputter etching

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Rutledge, Sharon K.

    1986-01-01

    An ion beam etching process which forms extremely high aspect ratio surface microstructures using thin sputter masks is utilized in the fabrication of integrated circuits. A carbon rich sputter mask together with unmasked portions of a substrate is bombarded with inert gas ions while simultaneous carbon deposition occurs. The arrival of the carbon deposit is adjusted to enable the sputter mask to have a near zero or even slightly positive increase in thickness with time while the unmasked portions have a high net sputter etch rate.

  1. Switching speed effect of phase shift keying in SLED for generating high power microwaves

    NASA Astrophysics Data System (ADS)

    Xiong, Zheng-Feng; Cheng, Cheng; Yu, Jian; Chen, Huai-Bi; Ning, Hui

    2016-01-01

    SLAC energy doubler (SLED) type radio-frequency pulse compressors are widely used in large-scale particle accelerators for converting long-duration moderate-power input pulses into short-duration high-power output pulses. Phase shift keying (PSK) is one of the key components in SLED pulse compression systems. Performance of the PSK will influence the output characteristics of the SLED, such as the rise-time of the output pulse, maximal peak power gain, and energy efficiency. In this paper, a high power microwave source based on power combining and pulse compression of conventional klystrons is introduced. The effects of nonideal PSK with slow switching speed and PSK without power output during the switching process are investigated, and the experimental results with nonideal PSK agree well with the analytical results.

  2. High power diode lasers for solid-state laser pumps

    NASA Technical Reports Server (NTRS)

    Linden, Kurt J.; Mcdonnell, Patrick N.

    1994-01-01

    The development and commercial application of high power diode laser arrays for use as solid-state laser pumps is described. Such solid-state laser pumps are significantly more efficient and reliable than conventional flash-lamps. This paper describes the design and fabrication of diode lasers emitting in the 780 - 900 nm spectral region, and discusses their performance and reliability. Typical measured performance parameters include electrical-to-optical power conversion efficiencies of 50 percent, narrow-band spectral emission of 2 to 3 nm FWHM, pulsed output power levels of 50 watts/bar with reliability values of over 2 billion shots to date (tests to be terminated after 10 billion shots), and reliable operation to pulse lengths of 1 ms. Pulse lengths up to 5 ms have been demonstrated at derated power levels, and CW performance at various power levels has been evaluated in a 'bar-in-groove' laser package. These high-power 1-cm stacked-bar arrays are now being manufactured for OEM use. Individual diode laser bars, ready for package-mounting by OEM customers, are being sold as commodity items. Commercial and medical applications of these laser arrays include solid-state laser pumping for metal-working, cutting, industrial measurement and control, ranging, wind-shear/atmospheric turbulence detection, X-ray generation, materials surface cleaning, microsurgery, ophthalmology, dermatology, and dental procedures.

  3. High power diode lasers for solid-state laser pumps

    NASA Astrophysics Data System (ADS)

    Linden, Kurt J.; McDonnell, Patrick N.

    1994-02-01

    The development and commercial application of high power diode laser arrays for use as solid-state laser pumps is described. Such solid-state laser pumps are significantly more efficient and reliable than conventional flash-lamps. This paper describes the design and fabrication of diode lasers emitting in the 780 - 900 nm spectral region, and discusses their performance and reliability. Typical measured performance parameters include electrical-to-optical power conversion efficiencies of 50 percent, narrow-band spectral emission of 2 to 3 nm FWHM, pulsed output power levels of 50 watts/bar with reliability values of over 2 billion shots to date (tests to be terminated after 10 billion shots), and reliable operation to pulse lengths of 1 ms. Pulse lengths up to 5 ms have been demonstrated at derated power levels, and CW performance at various power levels has been evaluated in a 'bar-in-groove' laser package. These high-power 1-cm stacked-bar arrays are now being manufactured for OEM use. Individual diode laser bars, ready for package-mounting by OEM customers, are being sold as commodity items. Commercial and medical applications of these laser arrays include solid-state laser pumping for metal-working, cutting, industrial measurement and control, ranging, wind-shear/atmospheric turbulence detection, X-ray generation, materials surface cleaning, microsurgery, ophthalmology, dermatology, and dental procedures.

  4. High-Power Microwave Breakdown of Dielectric Interfaces.

    NASA Astrophysics Data System (ADS)

    Calico, Steve Eugene

    A project to study the electrical breakdown of microwave windows due to high-power pulsed microwave fields was undertaken at Texas Tech University. The pulsed power equipment was acquired from the Air Force Weapons Laboratory in Albuquerque, NM, refurbished and redesigned as necessary, and serves as the high-power microwave source. The microwaves are used to test various vacuum to atmosphere interfaces (windows) in an attempt to isolate the mechanisms governing the electrical breakdown at the window. Windows made of three different materials and of three basic geometrical designs were tested in this experiment. Additionally, the surfaces of two windows were sanded with different grit sandpapers to determine the effect the surface texture has on the breakdown. The windows were tested in atmospheric pressure air, argon, helium, and to a lesser extent sulfur-hexafluoride. Estimates of the breakdown threshold in air and argon on a Lexan window were obtained as a consequence of these tests and were found to be considerably lower than that reported for pulsed microwave breakdown in gases. A hypothesis is presented in an attempt to explain the lower breakdown phenomena. A discussion of the comparative performance of the windows and an explanation as to the enhanced performance of some windows is given.

  5. Ultra-sensitive Absorption Diagnostics of Thin Films for High-power Laser Interference Coatings

    DTIC Science & Technology

    2015-01-05

    Jorge Rocca at Colorado State University who conduct laser research and uses a Veeco Spector Ion Beam Sputtering system to grow dielectric IC for...pulsed pump laser beams . Results obtained in this project demonstrated the method can measure absorption losses below 10 ppm at 1 µm wavelength. Future...modulated and pulsed pump laser beams . Results obtained in this project demonstrated the method can measure absorption losses below 10 ppm at 1 µm

  6. High power testing of a 17 GHz photocathode RF gun

    SciTech Connect

    Chen, S.C.; Danly, B.G.; Gonichon, J.

    1995-12-31

    The physics and technological issues involved in high gradient particle acceleration at high microwave (RF) frequencies are under study at MIT. The 17 GHz photocathode RF gun has a 1 1/2 cell ({pi} mode) room temperature cooper cavity. High power tests have been conducted at 5-10 MW levels with 100 ns pulses. A maximum surface electric field of 250 MV/m was achieved. This corresponds to an average on-axis gradient of 150 MeV/m. The gradient was also verified by a preliminary electron beam energy measurement. Even high gradients are expected in our next cavity design.

  7. High-power picosecond fiber source for coherent Raman microscopy.

    PubMed

    Kieu, Khanh; Saar, Brian G; Holtom, Gary R; Xie, X Sunney; Wise, Frank W

    2009-07-01

    We report a high-power picosecond fiber pump laser system for coherent Raman microscopy (CRM). The fiber laser system generates 3.5 ps pulses with 6 W average power at 1030 nm. Frequency doubling yields more than 2 W of green light, which can be used to pump an optical parametric oscillator to produce the pump and the Stokes beams for CRM. Detailed performance data on the laser and the various wavelength conversion steps are discussed, together with representative CRM images of fresh animal tissue obtained with the new source.

  8. Very high power THz radiation at Jefferson Lab

    SciTech Connect

    Carr, G.L.; Martin, Michael C.; McKinney, Wayne R.; Jordan, K.; Neil, George R.; Williams, G.P.

    2002-03-31

    We report the production of high power (20 watts average, {approx};1 Megawatt peak) broadband THz light based on coherent emission from relativistic electrons. We describe the source, presenting theoretical calculations and their experimental verification. For clarity we compare this source with one based on ultrafast laser techniques, and in fact the radiation has qualities closely analogous to that produced by such sources, namely that it is spatially coherent, and comprises short duration pulses with transform-limited spectral content. In contrast to conventional THz radiation, however, the intensity is many orders of magnitude greater due to the relativistic enhancement.

  9. Very high Power THz radiation at Jefferson Lab

    SciTech Connect

    G.L. Carr; Michael C. Martin; Wayne R. McKinney; Kevin Jordan; George R. Neil; Gwyn P. Williams

    2002-03-01

    We report the production of high power (20 watts average, {approx}1 Megawatt peak) broadband THz light based on coherent emission from relativistic electrons. We describe the source, presenting theoretical calculations and their experimental verification. For clarity we compare this source with one based on ultrafast laser techniques, and in fact the radiation has qualities closely analogous to that produced by such sources, namely that it is spatially coherent, and comprises short duration pulses with transform-limited spectral content. In contrast to conventional THz radiation, however, the intensity is many orders of magnitude greater due to the relativistic enhancement.

  10. Very high power THz radiation at Jefferson Lab.

    PubMed

    Carr, G L; Martin, Michael C; McKinney, Wayne R; Jordan, K; Neil, George R; Williams, G P

    2002-11-07

    We report the production of high power (20 W average, approximately 1 MW peak) broadband THz light based on coherent emission from relativistic electrons. We describe the source, presenting theoretical calculations and their experimental verification. For clarity we compare this source with that based on ultrafast laser techniques, and in fact the radiation has qualities closely analogous to those produced by such sources, namely that it is spatially coherent, and comprises short duration pulses with transform-limited spectral content. In contrast to conventional THz radiation, however, the intensity is many orders of magnitude greater due to the relativistic enhancement.

  11. HPM (high power microwave) testing of electronic components

    SciTech Connect

    Antinone, R.; Ng, W.C.

    1989-05-10

    This report documents the results of a study of high power microwave (HPM) vulnerability of electronic components commonly used in weapon systems. The study was carried out at the Lawrence Livermore National Laboratory from August through October 1988. The objective of this study was to determine the threshold levels for upset or disturbance and damage of the devices under test (DUT). In these tests pulsed microwave energy was directly injected into the terminal of the DUT and in most cases a 50-ohm microstrip test fixture was used to ensure that 50-ohm transmission was maintained as close to the DUT as possible. 3 refs., 41 figs., 10 tabs.

  12. Theory and Modeling of High-Power Gyrotrons

    SciTech Connect

    Nusinovich, Gregory Semeon

    2016-04-29

    This report summarized results of the work performed at the Institute for Research in Electronics and Applied Physics of the University of Maryland (College Park, MD) in the framework of the DOE Grant “Theory and Modeling of High-Power Gyrotrons”. The report covers the work performed in 2011-2014. The research work was performed in three directions: - possibilities of stable gyrotron operation in very high-order modes offering the output power exceeding 1 MW level in long-pulse/continuous-wave regimes, - effect of small imperfections in gyrotron fabrication and alignment on the gyrotron efficiency and operation, - some issues in physics of beam-wave interaction in gyrotrons.

  13. High power millimeter wave source development program

    NASA Technical Reports Server (NTRS)

    George, T. V.

    1989-01-01

    High power millimeter wave sources for fusion program; ECH source development program strategy; and 1 MW, 140 GHz gyrotron experiment design philosophy are briefly outlined. This presentation is represented by viewgraphs only.

  14. High power, high frequency component test facility

    NASA Technical Reports Server (NTRS)

    Roth, Mary Ellen; Krawczonek, Walter

    1990-01-01

    The NASA Lewis Research Center has available a high frequency, high power laboratory facility for testing various components of aerospace and/or terrestrial power systems. This facility is described here. All of its capabilities and potential applications are detailed.

  15. High power plasma spraying of oxide ceramics

    SciTech Connect

    Lugscheider, E.; Jungklaus, H.; Schwier, G.; Mathesius, H.; Heinrich, P.

    1995-12-31

    New developed high power plasma spray (HPPS) systems offer opportunities for generating both high thermal as well as high kinetic energy transfer to the powder particles. The operation level can be elevated up to 250 kW for continuous processing. PLCs and mass flow controls support high power processing under production conditions. The process is designed for applying large quantities even of high melt materials, such as oxide ceramics. High power plasma processing may result in enhanced coating characteristics. The work in this paper shows first conclusions for processing commercial powders such as alumina, alumina-titania, chromia and a recently developed multicomponent oxide with a HPPS system. Particle velocities were measured after optimizing spraying parameters. Coatings were evaluated by optical microscopy (microstructure and porosity), microhardness and pin-on-disc abrasive wear tests. Powder types and sizes as well as the systems configuration are considered for a general discussion of the capability and limitation in high power plasma spraying.

  16. Test facilities for high power electric propulsion

    NASA Technical Reports Server (NTRS)

    Sovey, James S.; Vetrone, Robert H.; Grisnik, Stanley P.; Myers, Roger M.; Parkes, James E.

    1991-01-01

    Electric propulsion has applications for orbit raising, maneuvering of large space systems, and interplanetary missions. These missions involve propulsion power levels from tenths to tens of megawatts, depending upon the application. General facility requirements for testing high power electric propulsion at the component and thrust systems level are defined. The characteristics and pumping capabilities of many large vacuum chambers in the United States are reviewed and compared with the requirements for high power electric propulsion testing.

  17. Very high power THz radiation sources

    SciTech Connect

    Carr, G.L.; Martin, Michael C.; McKinney, Wayne R.; Jordan, K.; Neil, George R.; Williams, G.P.

    2002-10-31

    We report the production of high power (20 watts average, {approx} 1 Megawatt peak) broadband THz light based on coherent emission from relativistic electrons. Such sources are ideal for imaging, for high power damage studies and for studies of non-linear phenomena in this spectral range. We describe the source, presenting theoretical calculations and their experimental verification. For clarity we compare this source to one based on ultrafast laser techniques.

  18. Very High Power THz Radiation Sources

    SciTech Connect

    G.L. Carr; Michael C. Martin; Wayne R. McKinney; Kevin Jordan; George R. Neil; Gwyn P. Williams

    2002-10-01

    We report the production of high power (20 watts average, {approx}1 Megawatt peak) broadband THz light based on coherent emission from relativistic electrons. Such sources are ideal for imaging, for high power damage studies and for studies of non-linear phenomena in this spectral range. We describe the source, presenting theoretical calculations and their experimental verification. For clarity, we compare this sources with one based on ultrafast laser techniques.

  19. ULTRA HIGH POWER TRANSMISSION LINE TECHNIQUES

    DTIC Science & Technology

    The ultra-high power transmission line techniques including both failure mechanisms and component design are discussed. Failures resulting from...a waveguide. In view of the many advantages of the low loss mode in circular waveguide for ultra-high power levels, a mode transducer and a two...percent of the peak power of a standard rectangular wave guide. Water cooling is provided for high average power operation. Analysis of mode sup pression

  20. High power infrared QCLs: advances and applications

    NASA Astrophysics Data System (ADS)

    Patel, C. Kumar N.

    2012-01-01

    QCLs are becoming the most important sources of laser radiation in the midwave infrared (MWIR) and longwave infrared (LWIR) regions because of their size, weight, power and reliability advantages over other laser sources in the same spectral regions. The availability of multiwatt RT operation QCLs from 3.5 μm to >16 μm with wall plug efficiency of 10% or higher is hastening the replacement of traditional sources such as OPOs and OPSELs in many applications. QCLs can replace CO2 lasers in many low power applications. Of the two leading groups in improvements in QCL performance, Pranalytica is the commercial organization that has been supplying the highest performance QCLs to various customers for over four year. Using a new QCL design concept, the non-resonant extraction [1], we have achieved CW/RT power of >4.7 W and WPE of >17% in the 4.4 μm - 5.0 μm region. In the LWIR region, we have recently demonstrated QCLs with CW/RT power exceeding 1 W with WPE of nearly 10 % in the 7.0 μm-10.0 μm region. In general, the high power CW/RT operation requires use of TECs to maintain QCLs at appropriate operating temperatures. However, TECs consume additional electrical power, which is not desirable for handheld, battery-operated applications, where system power conversion efficiency is more important than just the QCL chip level power conversion efficiency. In high duty cycle pulsed (quasi-CW) mode, the QCLs can be operated without TECs and have produced nearly the same average power as that available in CW mode with TECs. Multiwatt average powers are obtained even in ambient T>70°C, with true efficiency of electrical power-to-optical power conversion being above 10%. Because of the availability of QCLs with multiwatt power outputs and wavelength range covering a spectral region from ~3.5 μm to >16 μm, the QCLs have found instantaneous acceptance for insertion into multitude of defense and homeland security applications, including laser sources for infrared

  1. Waveform agile high-power fiber laser illuminators for directed-energy weapon systems

    NASA Astrophysics Data System (ADS)

    Engin, Doruk; Lu, Wei; Kimpel, Frank; Gupta, Shantanu

    2012-06-01

    A kW-class fiber-amplifier based laser illuminator system at 1030nm is demonstrated. At 125 kHz pulse repetition rate, 1.9mJ energy per pulse (235W average power) is achieved for 100nsec pulses with >72% optical conversion efficiency, and at 250kHz repetition, >350W average power is demonstrated, limited by the available pumps. Excellent agreement is established between the experimental results and dynamic fiber amplifier simulation, for predicting the pulse shape, spectrum and ASE accumulation throughout the fiber-amplifier chain. High pulse-energy, high power fiber-amplifier operation requires careful engineering - minimize ASE content throughout the pre-amplifier stages, use of large mode area gain fiber in the final power stage for effective pulse energy extraction, and pulse pre-shaping to compensate for the laser gain-saturation induced intra-pulse and pulse-pattern dependent distortion. Such optimization using commercially available (VLMA) fibers with core size in the 30-40μm range is estimated to lead to >4mJ pulse energy for 100nsec pulse at 50kHz repetition rate. Such waveform agile high-power, high-energy pulsed fiber laser illuminators at λ=1030nm satisfies requirements for active-tracking/ranging in high-energy laser (HEL) weapon systems, and in uplink laser beacon for deep space communication.

  2. Active cooling solutions for high power laser diodes stacks

    NASA Astrophysics Data System (ADS)

    Karni, Yoram; Klumel, Genady; Levy, Moshe; Berk, Yuri; Openhaim, Yaki; Gridish, Yaakov; Elgali, Asher; Avisar, Meir; Blonder, Moshe; Sagy, Hila; Gertsenshtein, Alex

    2008-02-01

    High power water cooled diode lasers find increasing demand in biomedical, cosmetic and industrial applications, where very high brightness and power are required. The high brightness is achieved either by increasing the power of each bar or by reducing the emitting area of the stacks. Two new products will be presented: Horizontal CW stacks with output power as high as 1kW using 80 W bars with emitting area width as low as 50 μm Vertical QCW stacks with output power as high as 1.2kW using 120 W bars. Heat removal from high power laser stacks often requires microchannel coolers operated with finely filtered deionized (DI) water. However, for certain industrial applications the reliability of this cooling method is widely considered insufficient due to leakage failures caused the highly corrosive DI water. Two solutions to the above problem will be discussed. A microchannel cooler-based package, which vastly reduces the corrosion problem, and a novel high-power laser diode stack that completely eliminates it. The latter solution is especially effective for pulsed applications in high duty cycle range.

  3. Freeform beam shaping for high-power multimode lasers

    NASA Astrophysics Data System (ADS)

    Laskin, Alexander; Laskin, Vadim

    2014-03-01

    Widening of using high power multimode lasers in industrial laser material processing is accompanied by special requirements to irradiance profiles in such technologies like metal or plastics welding, cladding, hardening, brazing, annealing, laser pumping and amplification in MOPA lasers. Typical irradiance distribution of high power multimode lasers: free space solid state, fiber-coupled solid state and diodes lasers, fiber lasers, is similar to Gaussian. Laser technologies can be essentially improved when irradiance distribution on a workpiece is uniform (flattop) or inverse-Gauss; when building high-power pulsed lasers it is possible to enhance efficiency of pumping and amplification by applying super-Gauss irradiance distribution with controlled convexity. Therefore, "freeform" beam shaping of multimode laser beams is an important task. A proved solution is refractive field mapping beam shaper like Shaper capable to control resulting irradiance profile - with the same unit it is possible to get various beam profiles and choose optimum one for a particular application. Operational principle of these devices implies transformation of laser irradiance distribution by conserving beam consistency, high transmittance, providing collimated low divergent output beam. Using additional optics makes it possible to create resulting laser spots of necessary size and round, elliptical or linear shape. Operation out of focal plane and, hence, in field of lower wavefront curvature, allows extending depth of field. The refractive beam shapers are implemented as telescopes and collimating systems, which can be connected directly to fiber-coupled lasers or fiber lasers, thus combining functions of beam collimation and irradiance transformation.

  4. Effect of sputtering power on the magnetic properties of amorphous perpendicular TbFeCo films

    NASA Astrophysics Data System (ADS)

    Wang, Ke; Huang, Ya; Xu, Zhan; Dong, Shuo; Chen, Ruofei

    2017-02-01

    A series of amorphous perpendicular TbFeCo films are sputtered using a composite target. The magnetic properties of the TbFeCo films are found to strongly be influenced by sputtering power. The above-RT magnetic compensation point in the films sputtered at high powers is revealed by thermomagnetic measurements. With increasing the power the compensation point shifts considerably towards higher temperature, while only a slight reduction in the Curie temperature occurs. The coercivity is found to initially increase with the power and then falls, which is in accordance with film composition moving from FeCo-rich to Tb-rich side. This can be well explained by the sputtering yield of Tb, which increases faster than FeCo atoms with the power during the sputtering. Our results show a convenient way to adjust the coercivity of the films by modifying the Tb-to-FeCo ratio using the sputtering power.

  5. Radial current high power dummy load for characterizing the high power laser triggered transformer-type accelerator

    NASA Astrophysics Data System (ADS)

    Yin, Yi; Zhong, Hui-Huang; Liu, Jin-Liang; Ren, He-Ming; Yang, Jian-Hua; Zhang, Xiao-Ping; Hong, Zhi-qiang

    2010-09-01

    A radial-current aqueous resistive solution load was applied to characterize a laser triggered transformer-type accelerator. The current direction in the dummy load is radial and is different from the traditional load in the axial. Therefore, this type of dummy load has smaller inductance and fast response characteristic. The load was designed to accommodate both the resistance requirement of accelerator and to allow optical access for the laser. Theoretical and numerical calculations of the load's inductance and capacitance are given. The equivalent circuit of the dummy load is calculated in theory and analyzed with a PSPICE code. The simulation results agree well with the theoretical analysis. At last, experiments of the dummy load applied to the high power spiral pulse forming line were performed; a quasisquare pulse voltage is obtained at the dummy load.

  6. Radial current high power dummy load for characterizing the high power laser triggered transformer-type accelerator.

    PubMed

    Yin, Yi; Zhong, Hui-Huang; Liu, Jin-Liang; Ren, He-Ming; Yang, Jian-Hua; Zhang, Xiao-Ping; Hong, Zhi-qiang

    2010-09-01

    A radial-current aqueous resistive solution load was applied to characterize a laser triggered transformer-type accelerator. The current direction in the dummy load is radial and is different from the traditional load in the axial. Therefore, this type of dummy load has smaller inductance and fast response characteristic. The load was designed to accommodate both the resistance requirement of accelerator and to allow optical access for the laser. Theoretical and numerical calculations of the load's inductance and capacitance are given. The equivalent circuit of the dummy load is calculated in theory and analyzed with a PSPICE code. The simulation results agree well with the theoretical analysis. At last, experiments of the dummy load applied to the high power spiral pulse forming line were performed; a quasisquare pulse voltage is obtained at the dummy load.

  7. High-power red VCSEL arrays

    NASA Astrophysics Data System (ADS)

    Seurin, Jean-Francois; Khalfin, Viktor; Xu, Guoyang; Miglo, Alexander; Li, Daizong; Zhou, Delai; Sundaresh, Mukta; Zou, Wei-Xiong; Lu, Chien-Yao; Wynn, James D.; Ghosh, Chuni

    2013-03-01

    High-power red laser sources are used in many applications such as cosmetics, cancer photodynamic therapy, and DNA sequencing in the medical field, laser-based RGB projection display, and bar-code scanning to name a few. Verticalcavity surface-emitting lasers (VCSELs) can be used as high-power laser sources, as efficient single devices can be configured into high-power two-dimensional arrays and scaled into modules of arrays. VCSELs emit in a circular, uniform beam which can greatly reduce the complexity and cost of optics. Other advantages include a narrow and stable emission spectrum, low speckle of the far-field emission, and good reliability. However, developing efficient red VCSEL sources presents some challenges because of the reduced quantum-well carrier confinement and the increased Aluminum content (to avoid absorption) which increases thermal impedance, and also decreases the DBR index contrast resulting in increased penetration length and cavity losses. We have recently developed VCSEL devices lasing in the visible 6xx nm wavelength band, and reaching 30% power conversion efficiency. We fabricated high-power 2D arrays by removing the GaAs substrate entirely and soldered the chips on high thermal conductivity submounts. Such arrays have demonstrated several Watts of output power at room temperature, in continuous-wave (CW) operation. Several tens of Watts are obtained in QCW operation. Results and challenges of these high-power visible VCSEL arrays will be discussed.

  8. Advances in high power semiconductor diode lasers

    NASA Astrophysics Data System (ADS)

    Ma, Xiaoyu; Zhong, Li

    2008-03-01

    High power semiconductor lasers have broad applications in the fields of military and industry. Recent advances in high power semiconductor lasers are reviewed mainly in two aspects: improvements of diode lasers performance and optimization of packaging architectures of diode laser bars. Factors which determine the performance of diode lasers, such as power conversion efficiency, temperature of operation, reliability, wavelength stabilization etc., result from a combination of new semiconductor materials, new diode structures, careful material processing of bars. The latest progress of today's high-power diode lasers at home and abroad is briefly discussed and typical data are presented. The packaging process is of decisive importance for the applicability of high-power diode laser bars, not only technically but also economically. The packaging techniques include the material choosing and the structure optimizing of heat-sinks, the bonding between the array and the heat-sink, the cooling and the fiber coupling, etc. The status of packaging techniques is stressed. There are basically three different diode package architectural options according to the integration grade. Since the package design is dominated by the cooling aspect, different effective cooling techniques are promoted by different package architectures and specific demands. The benefit and utility of each package are strongly dependent upon the fundamental optoelectronic properties of the individual diode laser bars. Factors which influence these properties are outlined and comparisons of packaging approaches for these materials are made. Modularity of package for special application requirements is an important developing tendency for high power diode lasers.

  9. Sputtering of uranium

    NASA Technical Reports Server (NTRS)

    Gregg, R.; Tombrello, T. A.

    1978-01-01

    Results are presented for an experimental study of the sputtering of U-235 atoms from foil targets by hydrogen, helium, and argon ions, which was performed by observing tracks produced in mica by fission fragments following thermal-neutron-induced fission. The technique used allowed measurements of uranium sputtering yields of less than 0.0001 atom/ion as well as yields involving the removal of less than 0.01 monolayer of the uranium target surface. The results reported include measurements of the sputtering yields for 40-120-keV protons, 40-120-keV He-4(+) ions, and 40- and 80-keV Ar-40(+) ions, the mass distribution of chunks emitted during sputtering by the protons and 80-keV Ar-40(+) ions, the total chunk yield during He-4(+) sputtering, and some limited data on molecular sputtering by H2(+) and H3(+). The angular distribution of the sputtered uranium is discussed, and the yields obtained are compared with the predictions of collision cascade theory.

  10. Optical design of a high power fiber optic coupler

    SciTech Connect

    English, R.E. Jr.; Halpin, J.M.; House, F.A.; Paris, R.D.

    1991-06-19

    Fiber optic beam delivery systems are replacing conventional mirror delivery systems for many reasons (e.g., system flexibility and redundancy, stability, and ease of alignment). Commercial products are available that use of fiber optic delivery for laser surgery and materials processing. Also, pump light of dye lasers can be delivered by optical fibers. Many laser wavelengths have been transported via optical fibers; high power delivery has been reported for argon, Nd:YAG, and excimer. We have been developing fiber optic beam delivery systems for copper vapor laser light; many of the fundamental properties of these systems are applicable to other high power delivery applications. A key element of fiber optic beam delivery systems is the coupling of laser light into the optical fiber. For our application this optical coupler must be robust to a range of operating parameters and laser characteristics. We have access to a high power copper vapor laser beam that is generated by a master oscillator/power amplifier (MOPA) chain comprised of three amplifiers. The light has a pulse width of 40--50 nsec with a repetition rate of about 4 kHz. The average power (nominal) to be injected into a fiber is 200 W. (We will refer to average power in this paper.) In practice, the laser beam's direction and collimation change with time. These characteristics plus other mechanical and operational constraints make it difficult for our coupler to be opto-mechanically referenced to the laser beam. We describe specifications, design, and operation of an optical system that couples a high-power copper vapor laser beam into a large core, multimode fiber. The approach used and observations reported are applicable to fiber optic delivery applications. 6 refs., 6 figs.

  11. Magnetically attached sputter targets

    DOEpatents

    Makowiecki, D.M.; McKernan, M.A.

    1994-02-15

    An improved method and assembly for attaching sputtering targets to cathode assemblies of sputtering systems which includes a magnetically permeable material is described. The magnetically permeable material is imbedded in a target base that is brazed, welded, or soldered to the sputter target, or is mechanically retained in the target material. Target attachment to the cathode is achieved by virtue of the permanent magnets and/or the pole pieces in the cathode assembly that create magnetic flux lines adjacent to the backing plate, which strongly attract the magnetically permeable material in the target assembly. 11 figures.

  12. Magnetically attached sputter targets

    DOEpatents

    Makowiecki, Daniel M.; McKernan, Mark A.

    1994-01-01

    An improved method and assembly for attaching sputtering targets to cathode assemblies of sputtering systems which includes a magnetically permeable material. The magnetically permeable material is imbedded in a target base that is brazed, welded, or soldered to the sputter target, or is mechanically retained in the target material. Target attachment to the cathode is achieved by virtue of the permanent magnets and/or the pole pieces in the cathode assembly that create magnetic flux lines adjacent to the backing plate, which strongly attract the magnetically permeable material in the target assembly.

  13. High Power Co-Axial Coupler

    SciTech Connect

    Neubauer, M.; Dudas, A.; Rimmer, Robert A.; Guo, Jiquan; Williams, R. Scott

    2013-12-01

    A very high power Coax RF Coupler (MW-Level) is very desirable for a number of accelerator and commercial applications. For example, the development of such a coupler operating at 1.5 GHz may permit the construction of a higher-luminosity version of the Electron-Ion Collider (EIC) being planned at JLab. Muons, Inc. is currently funded by a DOE STTR grant to develop a 1.5-GHz high-power doublewindowcoax coupler with JLab (about 150 kW). Excellent progress has been made on this R&D project, so we propose an extension of this development to build a very high power coax coupler (MW level peak power and a max duty factor of about 4%). The dimensions of the current coax coupler will be scaled up to provide higher power capability.

  14. Hybrid antenna sources for radiating high-power impulsive fields

    NASA Astrophysics Data System (ADS)

    Buchenauer, C. Jerald; Marek, J. Raley

    1995-09-01

    The transmission of impulsive signals through baluns and feed lines, between high-power, fast-risetime pulse generators and impulse-radiating antennas, leads to degraded system performance and increased pulse risetime due to transit-time dispersion, skin and dielectric losses, and electrical breakdown effects. These loss mechanisms are greatly reduced in system designs that eliminate feed lines and baluns by combining the antenna and generator in a single hybrid device that is compact, simple, and robust. This paper describes generators in which the antenna itself is pulse charged to hundreds of kV and subsequently shorted at the feed point by an oil spark switch. These Hertzian generators maintain conical symmetry to within a few millimeters of the feed-point switch, thus providing conditions for launching near-ideal spherical TEM step waves for driving impulse-radiating, focused-aperture antennas. Careful attention to symmetry, optical principles, and precise methods of measurement has yielded subnanosecond pulse risetimes that are more than ten times faster than predictions from spark- switch scaling laws.

  15. High Power Terahertz Conductive Antenna with Chaotic Electrodes

    NASA Astrophysics Data System (ADS)

    Kim, Christopher; Graber, Benjamin; Wu, Dong Ho

    2015-03-01

    Time domain terahertz spectroscopy (TDTS) is now widely adopted and being used for various purposes, including chemical and material analysis as well as detection of hazardous materials in the laboratories. While there are several different methods available to generate a wideband terahertz pulse for the TDTS, currently a terahertz photoconductive antenna may be the most popular one, as it can produce a wideband terahertz pulse very efficiently. However our experimental investigation indicates that the conventional photoconductive antenna with a pair of parallel electrodes can produce a terahertz pulse at most about 100 micro-Watts. When attempted to produce a higher power terahertz pulse the antenna may experience irrevocable failure. In order to overcome this problem we recently redesigned the photoconductive antenna and implemented electrodes that lead to a chaotic trajectories of charged particles. With the new electrodes we have demonstrated a high power (>2 mW) coherent terahertz beam, and we found that the lifetime of the antenna is also substantially longer than that of the conventional antenna. In this talk I will present our experimental results and disclose some of our new antenna designs. Supported by DTRA and Naval Research Laboratory.

  16. Towards higher stability of resonant absorption measurements in pulsed plasmas

    SciTech Connect

    Britun, Nikolay; Michiels, Matthieu; Snyders, Rony

    2015-12-15

    Possible ways to increase the reliability of time-resolved particle density measurements in pulsed gaseous discharges using resonant absorption spectroscopy are proposed. A special synchronization, called “dynamic source triggering,” between a gated detector and two pulsed discharges, one representing the discharge of interest and another being used as a reference source, is developed. An internal digital delay generator in the intensified charge coupled device camera, used at the same time as a detector, is utilized for this purpose. According to the proposed scheme, the light pulses from the reference source follow the gates of detector, passing through the discharge of interest only when necessary. This allows for the utilization of short-pulse plasmas as reference sources, which is critical for time-resolved absorption analysis of strongly emitting pulsed discharges. In addition to dynamic source triggering, the reliability of absorption measurements can be further increased using simultaneous detection of spectra relevant for absorption method, which is also demonstrated in this work. The proposed methods are illustrated by the time-resolved measurements of the metal atom density in a high-power impulse magnetron sputtering (HiPIMS) discharge, using either a hollow cathode lamp or another HiPIMS discharge as a pulsed reference source.

  17. High power diode lasers reliability experiment

    NASA Astrophysics Data System (ADS)

    Lu, Guoguang; Xie, Shaofeng; Hao, Mingming; Huang, Yun; En, Yunfei

    2013-12-01

    In order to evaluate and obtain the actual lifetime data of high power laser diodes, an automated high power laser diodes reliability experiment was developed and reported in this paper. This computer controlled setup operates the laser diodes 24 hours a day, the parameters such as output power, wavelength were test once in one hour. The experiment has 60 work stations, the temperature control range is from 25°C to 70°C, and the output power of the aging device is beyond 20W.

  18. A High Power Frequency Doubled Fiber Laser

    NASA Technical Reports Server (NTRS)

    Thompson, Robert J.; Tu, Meirong; Aveline, Dave; Lundblad, Nathan; Maleki, Lute

    2003-01-01

    This viewgraph presentation reports on the development of a high power 780 nm laser suitable for space applications of laser cooling. A possible solution is to use frequency doubling of high power 1560 nm telecom lasers. The presentation shows a diagram of the frequency conversion, and a graph of the second harmonic generation in one crystal, and the use of the cascading crystals. Graphs show the second harmonic power as a function of distance between crystals, second harmonic power vs. pump power, tunability of laser systems.

  19. High Power Short Wavelength Laser Development

    DTIC Science & Technology

    1977-11-01

    Unlimited güä^äsjäsiiiüüü X NRTC-77-43R P I High Power Short Wavelength Laser Development November 1977 D. B. Cohn and W. B. Lacina...NO NRTC-77-43R, «. TITLE fana »uetjjitj BEFORE COMPLETING FORM CIPIENT’S CATALOO NUMBER KIGH.POWER SHORT WAVELENGTH LASER DEVELOPMENT , 7...fWhtn Data Enterte NRTC-77-43R HIGH POWER SHORT WAVELENGTH LASER DEVELOPMENT ARPA Order Number: Program Code Number: Contract Number: Principal

  20. Electromagnetic pulse bombs' defense

    NASA Astrophysics Data System (ADS)

    Chen, Bin; Wang, Yongbin; Li, Juan; Wang, Jianzhong

    2007-11-01

    With the high power microwave devices development, the high power microwave electromagnetic pulse bombs (E-bombs) have become practical abroad. The development of conventional E-bombs devices allows their use in nonnuclear confrontations. E-bombs are powerful enough to damage communication, radar, navigation and computer systems. This paper discusses effects of EMP on electrical system and how to defend the EMP.