Industrial Applications of Pulsed Power Technology

Science.gov (United States)

Takaki, Koichi; Katsuki, Sunao

Recent progress of the industrial applications of pulsed power is reviewed in this paper. Repetitively operated pulsed power generators with a moderate peak power have been developed for industrial applications. These generators are reliable and low maintenance. Development of the pulsed power generators helps promote industrial applications of pulsed power for such things as food processing, medical treatment, water treatment, exhaust gas treatment, ozone generation, engine ignition, ion implantation and others. Here, industrial applications of pulsed power are classified by application for biological effects, for pulsed streamer discharges in gases, for pulsed discharges in liquid or liquid-mixture, and for bright radiation sources.

Foundations of pulsed power technology

CERN Document Server

Lehr, Janet

2018-01-01

Pulsed power technologies could be an answer to many cutting-edge applications. The challenge is in how to develop this high-power/high-energy technology to fit current market demands of low-energy consuming applications. This book provides a comprehensive look at pulsed power technology and shows how it can be improved upon for the world of today and tomorrow. Foundations of Pulsed Power Technology focuses on the design and construction of the building blocks as well as their optimum assembly for synergetic high performance of the overall pulsed power system. Filled with numerous design examples throughout, the book offers chapter coverage on various subjects such as: Marx generators and Marx-like circuits; pulse transformers; pulse-forming lines; closing switches; opening switches; multi-gigawatt to multi-terawatt systems; energy storage in capacitor banks; electrical breakdown in gases; electrical breakdown in solids, liquids and vacuum; pulsed voltage and current measurements; electromagnetic interferen...

Dual comb generation from a mode-locked fiber laser with orthogonally polarized interlaced pulses.

Science.gov (United States)

Akosman, Ahmet E; Sander, Michelle Y

2017-08-07

Ultra-high precision dual-comb spectroscopy traditionally requires two mode-locked, fully stabilized lasers with complex feedback electronics. We present a novel mode-locked operation regime in a thulium-holmium co-doped fiber laser, a frequency-halved state with orthogonally polarized interlaced pulses, for dual comb generation from a single source. In a linear fiber laser cavity, an ultrafast pulse train composed of co-generated, equal intensity and orthogonally polarized consecutive pulses at half of the fundamental repetition rate is demonstrated based on vector solitons. Upon optical interference of the orthogonally polarized pulse trains, two stable microwave RF beat combs are formed, effectively down-converting the optical properties into the microwave regime. These co-generated, dual polarization interlaced pulse trains, from one all-fiber laser configuration with common mode suppression, thus provide an attractive compact source for dual-comb spectroscopy, optical metrology and polarization entanglement measurements.

Abnormal polarity effect in nanosecond-pulse breakdown of SF6 and nitrogen

International Nuclear Information System (INIS)

Shao, Tao; Tarasenko, Victor F.; Zhang, Cheng; Beloplotov, Dmitry S.; Yang, Wenjin; Lomaev, Mikhail I.; Zhou, Zhongsheng; Sorokin, Dmitry A.; Yan, Ping

2014-01-01

The breakdown of gas gaps in an inhomogeneous electric field at subnanosecond and nanosecond voltage pulse rise times are studied, and the famous polarity effect in point-to-plane gaps is investigated. It is shown that at a voltage pulse rise time of ∼0.5 ns, the inversion of polarity effect takes place not only in electronegative gases such as SF 6 , but also occurs in electropositive nitrogen. The inversion of polarity effect is related to a delay of electron emission from the plane cathode on arrival of the ionization wave front anode to the cathode. It is found that with a voltage pulse rise time of ∼0.5 ns, the inversion of polarity effect occurs at SF 6 and SF 6 –N 2 pressures of 0.25 MPa and lower, and with a voltage pulse rise time of 15 ns, at a SF 6 pressure lower than 0.12 MPa.

High peak power Q-switched Er:YAG laser with two polarizers and its ablation performance for hard dental tissues.

Science.gov (United States)

Yang, Jingwei; Wang, Li; Wu, Xianyou; Cheng, Tingqing; Jiang, Haihe

2014-06-30

An electro-optically Q-switched high-energy Er:YAG laser with two polarizers is proposed. By using two Al(2)O(3) polarizing plates and a LiNbO(3) crystal with Brewster angle, the polarization efficiency is significantly improved. As a result, 226 mJ pulse energy with 62 ns pulse width is achieved at the repetition rate of 3 Hz, the corresponding peak power is 3.6 MW. To our knowledge, such a high peak power has not been reported in literature. With our designed laser, in-vitro teeth were irradiated under Q-switched and free-running modes. Results of a laser ablation experiment on hard dental tissue with the high-peak-power laser demonstrates that the Q-switched Er:YAG laser has higher ablation precision and less thermal damage than the free-running Er:YAG laser.

Petawatt pulsed-power accelerator

Science.gov (United States)

Stygar, William A.; Cuneo, Michael E.; Headley, Daniel I.; Ives, Harry C.; Ives, legal representative; Berry Cottrell; Leeper, Ramon J.; Mazarakis, Michael G.; Olson, Craig L.; Porter, John L.; Wagoner; Tim C.

2010-03-16

A petawatt pulsed-power accelerator can be driven by various types of electrical-pulse generators, including conventional Marx generators and linear-transformer drivers. The pulsed-power accelerator can be configured to drive an electrical load from one- or two-sides. Various types of loads can be driven; for example, the accelerator can be used to drive a high-current z-pinch load. When driven by slow-pulse generators (e.g., conventional Marx generators), the accelerator comprises an oil section comprising at least one pulse-generator level having a plurality of pulse generators; a water section comprising a pulse-forming circuit for each pulse generator and a level of monolithic triplate radial-transmission-line impedance transformers, that have variable impedance profiles, for each pulse-generator level; and a vacuum section comprising triplate magnetically insulated transmission lines that feed an electrical load. When driven by LTD generators or other fast-pulse generators, the need for the pulse-forming circuits in the water section can be eliminated.

Performances of a Compact, High-Power WB Source with Circular Polarization

Science.gov (United States)

Delmote, P.; Pinguet, S.; Bieth, F.

This paper presents the design and the performances of an embedded high-power microwave (HPM) wideband source, developed and built at the French-German Research Institute of Saint-Louis. The system was intended for dual use, homeland security, and military applications. It is powered by a 400 kV compact Marx generator with specificities in coaxial design and low energy. The slow monopolar signal from the Marx is sharpened using a pulse-forming stage, made of a switching module pressurized with nitrogen, followed by a monopulse-to-monocycle converter. The duration and rise times of this signal could be adjusted by varying the pressure and space between electrodes. Repetitive operations were performed up to 100 Hz during 10 s without a gas flow. Two kinds of antennas can be connected to the source. The first one is a TEM horn, with an optional dielectric lens, that radiates a vertically polarized UWB short pulse. The second one is a nine-turn helix, working in Kraus monopolar axial mode and radiating a circularly polarized wideband signal along the main axis. A dedicated conical reflector increases its directivity and bandwidth. The whole source is designed to be embedded inside an aluminum trailer, powered by batteries and remote controlled through an optical fiber.

Pulsed power

International Nuclear Information System (INIS)

Anon.

1977-01-01

The key element of our pulsed power program is concentration of power in time and space by suppression of breakdown in dielectrics and in vacuum. Magnetically insulated vacuum transmission lines and magnetic suppression of insulator flashover have continued as the main reserch directions. Vacuum insulated line studies at Physics International have been expanded and a test bed at Sandia, called MITE (Magnetically Insulated Transmission Experiment), is under development. The choice for the baseline EBFA design will depend on the outcome of these studies and should be made in July 1977. The slow and intermediate speed pulsed power approaches to EBFA will be based on Proto I and Proto II results and several of the projected EBFA subsystems are presently being tested in Proto II. A further stage of power concentration, within the vacuum diode itself, would considerably ease the burden on dielectrics; methods of power multiplication involving magnetically imploded plasmas are being considered and tests have begun using the Ripple III apparatus

Designs of pulsed power cryogenic transformers

International Nuclear Information System (INIS)

Singh, S.K.; Heyne, C.J.; Hackowrth, D.T.; Shestak, E.J.; Eckels, P.W.; Rogers, J.D.

1988-01-01

The Westinghouse Electric Corporation has completed designs of three pulsed power cryogenic transformers of three pulsed power cryogenic transformers for the Los Alamos National Laboratory. These transformers will be configured to transfer their stored energy sequentially to an electro-magnetic launcher and form a three-stage power supply. The pulse transformers will act as two winding energy storage solenoids which provide a high current and energy pulse compression by transforming a 50 kA power supply into a megamp level power supply more appropriate for the electromagnetic launcher duty. This system differs from more traditional transformer applications in that significant current levels do not exists simultaneously in the two windings of the pulse transformer. This paper describes the designs of the pulsed power cryogenic transformers

Polarizing beam-splitter device at a pulsed neutron source

International Nuclear Information System (INIS)

Itoh, Shinichi; Takeda, Masayasu.

1996-01-01

A polarizing beam-splitter device was designed using Fe/Si supermirrors in order to obtain two polarized neutron beam lines, from one unpolarized neutron beam line, with a practical beam size for investigating the properties of condensed matter. This device was mounted after a guide tube at a pulsed neutron source, and its performance was investigated. (author)

Mg Incorporation Efficiency in Pulsed MOCVD of N-Polar GaN:Mg

Science.gov (United States)

Marini, Jonathan; Mahaboob, Isra; Hogan, Kasey; Novak, Steve; Bell, L. D.; Shahedipour-Sandvik, F.

2017-10-01

We report on the effect of growth polarity and pulsed or δ -doped growth mode on impurity incorporation in metalorganic chemical vapor deposition-grown GaN. In Ga-polar orientation, up to 12× enhancement in Mg concentration for given Mg flow rate is observed, resulting in enhanced p-type conductivity for these samples. In contrast, this enhancement effect is greatly diminished for N-polar samples, falling off with increasing Mg flow and showing maximum enhancement of 2.7× at 30 nmol/min Mg flow. At higher Mg flow rates, Mg incorporation at normal levels did not correspond to p-type conductivity, which may be due to Mg incorporation at nonacceptor sites. Concentrations of C, O, and Si were also investigated, revealing dependence on Mg flow in N-polar pulsed samples. Carbon incorporation was found to decrease with increasing Mg flow, and oxygen incorporation was found to remain high across varied Mg flow. These effects combine to result in N-polar samples that are not p-type when using the pulsed growth mode.

Status of the upgraded version of the NRL GAMBLE II pulse power generator

International Nuclear Information System (INIS)

Boller, J.R.; Burton, J.K.; Shipman, J.D. Jr.

1979-01-01

The GAMBLE II water dielectric pulse power generator, in 1970, was the forerunner of the high energy (> 50 kJ) class of water dielectric generators. It has been redesigned internally to make maximum use of its original outer conductor shell and to optimize it for the positive polarity mode of operation for positive ion beam experimentation. The new design also initiates the use of an oil dielectric multi-channel switch at the output of the pulse forming line. This switch, because of its low capacitance, eliminates the need for an extra prepulse switch. The upgraded version has been tested up to power and energy levels which are nearly twice the original

A high power gain switched diode laser oscillator and amplifier for the CEBAF polarized electron injector

International Nuclear Information System (INIS)

Poelker, M.; Hansknecht, J.

1996-01-01

The photocathode in the polarized electron source at Jefferson Lab is illuminated with pulsed laser light from a gain switched diode laser and diode optical amplifier. Laser pulse repetition rates up to 2,000 MHz, optical pulsewidths between 31 and 123 ps, and average power > 100 mW are demonstrated. The laser system is highly reliable and completely remotely controlled

Pulsed high-power beams

International Nuclear Information System (INIS)

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

1988-01-01

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%. This paper reports on a 70-MeV, 3-kA induction accelerator (ETA II) constructed at the Lawrence Livermore National Laboratory that 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 of 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

Effects of spin-polarized current on pulse field-induced precessional magnetization reversal

Directory of Open Access Journals (Sweden)

Guang-fu Zhang

2012-12-01

Full Text Available We investigate effects of a small DC spin-polarized current on the pulse field-induced precessional magnetization reversal in a thin elliptic magnetic element by micromagnetic simulations. We find that the spin-polarized current not only broadens the time window of the pulse duration, in which a successful precessional reversal is achievable, but also significantly suppresses the magnetization ringing after the reversal. The pulse time window as well as the decay rate of the ringing increase with increasing the current density. When a spin-polarized current with 5 MA/cm2 is applied, the time window increases from 80 ps to 112 ps, and the relaxation time of the ringing decreases from 1.1 ns to 0.32 ns. Our results provide useful information to achieve magnetic nanodevices based on precessional switching.

Efficient high-power narrow-linewidth all-fibred linearly polarized ytterbium laser source

Science.gov (United States)

Bertrand, Anthony; Liégeois, Flavien; Hernandez, Yves; Giannone, Domenico

2012-06-01

We report on experimental results on a high power, all-fibred, linearly polarized, mode-locked laser at 1.03 μm. The laser generates pulses of 40 ps wide at a repetition rate of 52 MHz, exhibiting 12 kW peak power. Dispersion in optical fibres is controlled to obtain both high power and narrow spectral linewidth. The average output power reached is 25 W with a spectral linewidth of 380 pm and a near diffraction limit beam (M2 < 1.2). This laser is an ideal candidate for applications like IR spectroscopy, where high peak power and narrow linewidth are required for subsequent wavelength conversion.

Erbium:ytterbium fiber-laser system delivering watt-level femtosecond pulses using divided pulse amplification

Science.gov (United States)

Herda, Robert; Zach, Armin

2015-03-01

We present an Erbium:Ytterbium codoped fiber-amplifer system based on Divided-Pulses-Amplification (DPA) for ultrashort pulses. The output from a saturable-absorber mode-locked polarization-maintaining (PM) fiber oscillator is amplified in a PM normal-dispersion Erbium-doped fiber. After this stage the pulses are positively chirped and have a duration of 2.0 ps at an average power of 93 mW. A stack of 5 birefringent Yttrium-Vanadate crystals divides these pulses 32 times. We amplify these pulses using a double-clad Erbium:Ytterbium codoped fiber pumped through a multimode fiber combiner. The pulses double pass the amplifier and recombine in the crystals using non-reciprocal polarization 90° rotation by a Faraday rotating mirror. Pulses with a duration of 144 fs are obtained after separation from the input beam using a polarizing beam splitter cube. These pulses have an average power of 1.85 W at a repetition rate of 80 MHz. The generation of femtosecond pulses directly from the amplifier was enabled by a positively chirped seed pulse, normally dispersive Yttrium-Vanadate crystals, and anomalously dispersive amplifier fibers. Efficient frequency doubling to 780 nm with an average power of 725 mW and a pulse duration of 156 fs is demonstrated. In summary we show a DPA setup that enables the generation of femtosecond pulses at watt-level at 1560 nm without the need for further external dechirping and demonstrate a good pulse quality by efficient frequency doubling. Due to the use of PM fiber components and a Faraday rotator the setup is environmentally stable.

Pulsed Cs beam development for the BNL polarized H- source

International Nuclear Information System (INIS)

Alessi, J.G.

1983-01-01

A pulsed Cs + beam has been developed for use on a polarized H - source. Cesium ion production is by surface ionization using a porous tungsten ionizer. While satisfactory current pulses (5 to 10 mA greater than or equal to 0.5 ms) can be obtained, the pulse shapes are a sensitive function of the ionizer temperature and Cs surface coverage. The beam optical requirements are stringent, and the optics have been studied experimentally for both Cs + and Cs 0 beams. Computer calculations are in good agreement with the observed results. The present source has delivered 2.6 mA of Cs + through the interaction region of the polarized ion source, and as much as 2.0 particle mA of Cs 0 . A new source is being built which is designed to give 15 mA through the interaction region

Clipper circuit of pulse modulator used for klystron-5045 power supply

CERN Document Server

Akimov, A V

2001-01-01

While the operation of modulator to the pulsed transformer of klystron-5045, current through the primary winding of the pulse transformer (PT) continues to flow even upon the end of the klystron voltage operating pulse. This is determined by an energy stored in magnetizing inductance. The prolongation of magnetizing current passing process simultaneously with the premature choking of thyratron can cause high voltage of inverse polarity at the klystron, which cause the destruction of the cathode. We have considered the possibility of shortening time of magnetizing current passage for the charge of reasonable choice of clipper circuit parameters. The behavior of clipper circuit was studied in modulators used for the VEPP-5 (BINP, Russia) preinjector klystron power supply. The optimum operation run of the circuit was selected and its design features are described.

Effect of Pulse Polarity on Thresholds and on Non-monotonic Loudness Growth in Cochlear Implant Users.

Science.gov (United States)

Macherey, Olivier; Carlyon, Robert P; Chatron, Jacques; Roman, Stéphane

2017-06-01

Most cochlear implants (CIs) activate their electrodes non-simultaneously in order to eliminate electrical field interactions. However, the membrane of auditory nerve fibers needs time to return to its resting state, causing the probability of firing to a pulse to be affected by previous pulses. Here, we provide new evidence on the effect of pulse polarity and current level on these interactions. In experiment 1, detection thresholds and most comfortable levels (MCLs) were measured in CI users for 100-Hz pulse trains consisting of two consecutive biphasic pulses of the same or of opposite polarity. All combinations of polarities were studied: anodic-cathodic-anodic-cathodic (ACAC), CACA, ACCA, and CAAC. Thresholds were lower when the adjacent phases of the two pulses had the same polarity (ACCA and CAAC) than when they were different (ACAC and CACA). Some subjects showed a lower threshold for ACCA than for CAAC while others showed the opposite trend demonstrating that polarity sensitivity at threshold is genuine and subject- or electrode-dependent. In contrast, anodic (CAAC) pulses always showed a lower MCL than cathodic (ACCA) pulses, confirming previous reports. In experiments 2 and 3, the subjects compared the loudness of several pulse trains differing in current level separately for ACCA and CAAC. For 40 % of the electrodes tested, loudness grew non-monotonically as a function of current level for ACCA but never for CAAC. This finding may relate to a conduction block of the action potentials along the fibers induced by a strong hyperpolarization of their central processes. Further analysis showed that the electrodes showing a lower threshold for ACCA than for CAAC were more likely to yield a non-monotonic loudness growth. It is proposed that polarity sensitivity at threshold reflects the local neural health and that anodic asymmetric pulses should preferably be used to convey sound information while avoiding abnormal loudness percepts.

Interrogation of orbital structure by elliptically polarized intense femtosecond laser pulses

International Nuclear Information System (INIS)

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

2011-01-01

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

Ionization of oriented carbonyl sulfide molecules by intense circularly polarized laser pulses

DEFF Research Database (Denmark)

Dimitrovski, Darko; Abu-Samha, Mahmoud; Madsen, Lars Bojer

2011-01-01

We present combined experimental and theoretical results on strong-field ionization of oriented carbonyl sulfide molecules by circularly polarized laser pulses. The obtained molecular frame photoelectron angular distributions show pronounced asymmetries perpendicular to the direction of the molec......We present combined experimental and theoretical results on strong-field ionization of oriented carbonyl sulfide molecules by circularly polarized laser pulses. The obtained molecular frame photoelectron angular distributions show pronounced asymmetries perpendicular to the direction......-dimensionally-oriented polar molecules, in particular asymmetries in the emission direction of the photoelectrons. In the following article [Phys. Rev. A 83, 023406 (2011)] the focus is to understand strong-field ionization from three-dimensionally-oriented asymmetric top molecules, in particular the suppression of electron...

Simple and robust generation of ultrafast laser pulse trains using polarization-independent parallel-aligned thin films

Science.gov (United States)

Wang, Andong; Jiang, Lan; Li, Xiaowei; Wang, Zhi; Du, Kun; Lu, Yongfeng

2018-05-01

Ultrafast laser pulse temporal shaping has been widely applied in various important applications such as laser materials processing, coherent control of chemical reactions, and ultrafast imaging. However, temporal pulse shaping has been limited to only-in-lab technique due to the high cost, low damage threshold, and polarization dependence. Herein we propose a novel design of ultrafast laser pulse train generation device, which consists of multiple polarization-independent parallel-aligned thin films. Various pulse trains with controllable temporal profile can be generated flexibly by multi-reflections within the splitting films. Compared with other pulse train generation techniques, this method has advantages of compact structure, low cost, high damage threshold and polarization independence. These advantages endow it with high potential for broad utilization in ultrafast applications.

Long-pulse applications of pulse-forming lines for high-power linac application

International Nuclear Information System (INIS)

Hoeberling, R.F.; Tallerico, P.J.

1981-01-01

The ever present demands for high efficiency in the RF power stations for particle accelerators have caused increased interest in longer RF pulses (ten's of microseconds) for linacs such as the Pion Generator for Medical Irradiation (PIGMI) and Free Electron Laser (FEL). For either RF power station, a fundamental decision is whether to use a modulating anode/hard-tube driver or pulsed cathode/line-type pulser configuration. The choices in the extremes of low power for very long pulses or for very-high-power, short pulses are, respectively, a modulated anode/hard tube modulator and pulsed cathode/pulse forming line. However, the demarcation between these two extremes is not clearcut. The criteria (cost, flexibility performance, reliability, efficiency) that resulted in the RF station definition of these two specific systems will be described

Power pulsing of the CMOS sensor Mimosa 26

International Nuclear Information System (INIS)

Kuprash, Oleg

2013-01-01

Mimosa 26 is a monolithic active pixel sensor developed by IPHC (Strasbourg) and IRFU (Saclay) as a prototype for the ILC vertex detector studies. The resolution requirements for the ILC tracking detector are very extreme, demanding very low material in the detector, thus only air cooling can be considered. Power consumption has to be reduced as far as possible. The beam structure of the ILC allows the possibility of power pulsing: only for about the 1 ms long bunch train full power is required, and during the 199 ms long pauses between the bunch trains the power can be reduced to a minimum. Not being adapted for the power pulsing, the sensor shows in laboratory tests a good performance under power pulsing. The power pulsing allows to significantly reduce the heating of the chip and divides power consumption approximately by a factor of 6. In this report a summary of power pulsing studies using the digital readout of Mimosa 26 is given. -- Highlights: • First power pulsing studies using digital readout of Mimosa 26 CMOS sensor were done. • Fake hit rates under power pulsing conditions and under normal conditions were compared. • The measurements demonstrate that there is so far no showstopper to operate CMOS pixel sensors in power pulsing mode

Progress in pulsed power fusion

Energy Technology Data Exchange (ETDEWEB)

Quintenz, J P; Adams, R G; Bailey, J E [Sandia Labs., Albuquerque, NM (United States); and others

1997-12-31

Pulsed power offers an efficient, high energy, economical source of x-rays for inertial confinement fusion (ICF) research. Two main approaches to ICF driven with pulsed power accelerators are pursued: intense light ion beams and z-pinches. Recent progress in each approach and plans for future development is described. (author). 2 figs., 10 refs.

Progress in pulsed power fusion

International Nuclear Information System (INIS)

Quintenz, J.P.; Adams, R.G.; Bailey, J.E.

1996-01-01

Pulsed power offers an efficient, high energy, economical source of x-rays for inertial confinement fusion (ICF) research. Two main approaches to ICF driven with pulsed power accelerators are pursued: intense light ion beams and z-pinches. Recent progress in each approach and plans for future development is described. (author). 2 figs., 10 refs

Characterization of power IGBTs under pulsed power conditions

Energy Technology Data Exchange (ETDEWEB)

Dale, Gregory E [Los Alamos National Laboratory; Vangordon, James [UNIV OF MISSOURI; Kovaleski, Scott [UNIV OF MISSOURI

2009-01-01

The power insulated gate bipolar transistor (IGBT) is used in many types of applications. Although the use of the power IGBT has been well characterized for many continuous operation power electronics applications, little published information is available regarding the performance of a given IGBT under pulsed power conditions. Additionally, component libraries in circuit simulation software packages have a finite number of IGBTs. This paper presents a process for characterizing the performance of a given power IGBT under pulsed power conditions. Specifically, signals up to 3.5 kV and 1 kA with 1-10 {micro}s pulse widths have been applied to a Powerex QIS4506001 IGBT. This process utilizes least squares curve fitting techniques with collected data to determine values for a set of modeling parameters. These parameters were used in the Oziemkiewicz implementation of the Hefner model for the IGBT that is utilized in some circuit simulation software packages. After the nominal parameter values are determined, they can be inserted into the Oziemkiewicz implementation to simulate a given IGBT.

Pulsed power supply for Nova Upgrade

International Nuclear Information System (INIS)

Bacon, J.L.; Kajs, J.P.; Walls, A.; Weldon, W.F.; Zowarka, R.C.

1992-01-01

This report describes work carried out at the Center for Electromechanics at The University of Texas at Austin (CEM-UT). A baseline design of the Nova Upgrade has been completed by Lawrence Livermore National Laboratory. The Nova Upgrade is an 18 beamline Nd: glass laser design utilizing fully relayed 4x4 30 cm aperture segmented optical components. The laser thus consists of 288 independent beamlets nominally producing 1.5 to 2.0 MJ of 0.35 μm light in a 3 to 5 ns pulse. The laser design is extremely flexible and will allow a wide range of pulses to irradiate ICF targets. This facility will demonstrate ignition/gain and the scientific feasibility of ICF for energy and defense applications. The pulsed power requirements for the Nova Upgrade are given. CEM-UT was contracted to study and develop a design for a homopolar generator/inductor (HPG/inductor) opening switch system which would satisfy the pulsed power supply requirements of the Nova Upgrade. The Nd:glass laser amplifiers used in the Nova Upgrade will be powered by light from xenon flashlamps. The pulsed power supply for the Nova Upgrade powers the xenon flashlamps. This design and study was for a power supply to drive flashlamps

A high pulsed power supply system designed for pulsed high magnetic field

International Nuclear Information System (INIS)

Liu Kefu; Wang Shaorong; Zhong Heqing; Xu Yan; Pan Yuan

2008-01-01

This paper introduces the design of high pulsed power supply system for producing pulsed high magnetic field up to 70 T. This system consists of 58 sets of 55 μF of capacitor bank which provides 1.0 MJ energy storage. A set of vacuum closing switch is chosen as main switch for energy discharge into magnetic coil. A crowbar circuit with high power diodes in series with resistor is used to absorb the redundant energy and adjust pulse width. The resistance of magnetic coil changing with current is deduced by energy balance equations. A capacitor-charging power supply using a series-resonant, constant on-time variable frequency control, and zero-current switching charges the capacitor bank in one minute time with high efficiency. The pulsed power supply provides adjustable current and pulse width with 30 kA peak and 30 ms maximum. The primary experiments demonstrate the system reliability. This work provides an engineering guidance for future development of pulsed high magnetic field. (authors)

Supercoherent phenomena in pulsed power

International Nuclear Information System (INIS)

O'Rourke, R.C.

1983-01-01

This chapter proposes the formulation of programs of basic physics research to transform Pulsed Power Technology (PPT) to Pulsed Power Science and Technology (PPS and T) by formulating the laws of the quantized microscopic electromagnetic field; applying the microscopic electromagnetic field theory to the generation, propagation and deposition of pulses in nonlinear networks; learning more about the basic super coherent ''micro-structure'' in space and time of the many-photon states of pulsed laser beams; learning more about the basic super coherent ''micro-structure'' in space and time of the many-electronstates of pulsed electron and ion laser beams; and learning everything about the ''micro-picture'' of so-called ''dielectric breakdown'' and the associated absolute time delays. Promotes the idea that laser, electron and ion beams are similar kinds of pulses in the microscopic electromagnetic field. Presents expression for the microscopic electromagnetic field in order to show the role of supercoherence in PPS and T

Effect of polarization and focusing on laser pulse driven auto-resonant particle acceleration

International Nuclear Information System (INIS)

Sagar, Vikram; Sengupta, Sudip; Kaw, Predhiman

2014-01-01

The effect of laser polarization and focusing is theoretically studied on the final energy gain of a particle in the Auto-resonant acceleration scheme using a finite duration laser pulse with Gaussian shaped temporal envelope. The exact expressions for dynamical variables viz. position, momentum, and energy are obtained by analytically solving the relativistic equation of motion describing particle dynamics in the combined field of an elliptically polarized finite duration pulse and homogeneous static axial magnetic field. From the solutions, it is shown that for a given set of laser parameters viz. intensity and pulse length along with static magnetic field, the energy gain by a positively charged particle is maximum for a right circularly polarized laser pulse. Further, a new scheme is proposed for particle acceleration by subjecting it to the combined field of a focused finite duration laser pulse and static axial magnetic field. In this scheme, the particle is initially accelerated by the focused laser field, which drives the non-resonant particle to second stage of acceleration by cyclotron Auto-resonance. The new scheme is found to be efficient over two individual schemes, i.e., auto-resonant acceleration and direct acceleration by focused laser field, as significant particle acceleration can be achieved at one order lesser values of static axial magnetic field and laser intensity

Frequency-agile gyrotron for electron decoupling and pulsed dynamic nuclear polarization

Science.gov (United States)

Scott, Faith J.; Saliba, Edward P.; Albert, Brice J.; Alaniva, Nicholas; Sesti, Erika L.; Gao, Chukun; Golota, Natalie C.; Choi, Eric J.; Jagtap, Anil P.; Wittmann, Johannes J.; Eckardt, Michael; Harneit, Wolfgang; Corzilius, Björn; Th. Sigurdsson, Snorri; Barnes, Alexander B.

2018-04-01

We describe a frequency-agile gyrotron which can generate frequency-chirped microwave pulses. An arbitrary waveform generator (AWG) within the NMR spectrometer controls the microwave frequency, enabling synchronized pulsed control of both electron and nuclear spins. We demonstrate that the acceleration of emitted electrons, and thus the microwave frequency, can be quickly changed by varying the anode voltage. This strategy results in much faster frequency response than can be achieved by changing the potential of the electron emitter, and does not require a custom triode electron gun. The gyrotron frequency can be swept with a rate of 20 MHz/μs over a 670 MHz bandwidth in a static magnetic field. We have already implemented time-domain electron decoupling with dynamic nuclear polarization (DNP) magic angle spinning (MAS) with this device. In this contribution, we show frequency-swept DNP enhancement profiles recorded without changing the NMR magnet or probe. The profile of endofullerenes exhibits a DNP profile with a <10 MHz linewidth, indicating that the device also has sufficient frequency stability, and therefore phase stability, to implement pulsed DNP mechanisms such as the frequency-swept solid effect. We describe schematics of the mechanical and vacuum construction of the device which includes a novel flanged sapphire window assembly. Finally, we discuss how commercially available continuous-wave gyrotrons can potentially be converted into similar frequency-agile high-power microwave sources.

Interaction of high power ultrashort laser pulses with plasmas

International Nuclear Information System (INIS)

Geissler, M.

2000-12-01

The invention of short laser-pulses has opened a vast application range from testing ultra high-speed semiconductor devices to precision material processing, from triggering and tracing chemical reactions to sophisticated surgical applications in opthalmology and neurosurgery. In physical science, ultrashort light pulses enable researchers to follow ultrafast relaxation processes in the microcosm on time scale never before accessible and study light-matter-interactions at unprecedented intensity levels. The aim of this thesis is to investigate the interaction of ultrashort high power laser pulses with plasmas for a broad intensity range. First the ionization of atoms with intense laser fields is investigated. For sufficient strong and low frequent laser pulses, electrons can be removed from the core by a tunnel process through a potential barrier formed by the electric field of the laser. This mechanism is described by a well-established theory, but the interaction of few-cycle laser pulses with atoms can lead to regimes where the tunnel theory loses its validity. This regime is investigated and a new description of the ionization is found. Although the ionization plays a major role in many high-energy laser processes, there exist no simple and complete model for the evolution of laser pulses in field-ionizing media. A new propagation equation and the polarization response for field-ionizing media are presented and the results are compared with experimental data. Further the interaction of high power laser radiation with atoms result in nonlinear response of the electrons. The spectrum of this induced nonlinear dipole moment reaches beyond visible wavelengths into the x-ray regime. This effect is known as high harmonic generation (HHG) and is a promising tool for the generation of coherent shot wavelength radiation, but the conversions are still not efficient enough for most practical applications. Phase matching schemes to overcome the limitation are discussed

Pulsed Power: Sandia's Plans for the New Millenium

International Nuclear Information System (INIS)

Quintenz, Jeffrey P.

2000-01-01

Pulsed power science and engineering activities at Sandia National Laboratories grew out of a programmatic need for intense radiation sources to advance capabilities in radiographic imaging and to create environments for testing and certifying the hardness of components and systems to radiation in hostile environments. By the early 1970s, scientists in laboratories around the world began utilizing pulsed power drivers with very short (10s of nanoseconds) pulse lengths for Inertial Confinement Fusion (ICF) experiments. In the United States, Defense Programs within the Department of Energy has sponsored this research. Recent progress in pulsed power, specifically fast-pulsed-power-driven z pinches, in creating temperatures relevant to ICF has been remarkable. Worldwide developments in pulsed power technologies and increased applications in both defense and industry are contrasted with ever increasing stress on research and development tiding. The current environment has prompted us at Sandia to evaluate our role in the continued development of pulsed power science and to consider options for the future. This presentation will highlight our recent progress and provide an overview of our plans as we begin the new millennium

Polarization dependent nanostructuring of silicon with femtosecond vortex pulse

Directory of Open Access Journals (Sweden)

M. G. Rahimian

2017-08-01

Full Text Available We fabricated conical nanostructures on silicon with a tip dimension of ∼ 70 nm using a single twisted femtosecond light pulse carrying orbital angular momentum (ℓ=±1. The height of the nano-cone, encircled by a smooth rim, increased from ∼ 350 nm to ∼ 1 μm with the pulse energy and number of pulses, whereas the apex angle remained constant. The nano-cone height was independent of the helicity of the twisted light; however, it is reduced for linear polarization compared to circular at higher pulse energies. Fluid dynamics simulations show nano-cones formation when compressive forces arising from the radial inward motion of the molten material push it perpendicular to the surface and undergo re-solidification. Simultaneously, the radial outward motion of the molten material re-solidifies after reaching the cold boundary to form a rim. Overlapping of two irradiated spots conforms to the fluid dynamics model.

Dual polarized receiving steering antenna array for measurement of ultrawideband pulse polarization structure

Energy Technology Data Exchange (ETDEWEB)

Balzovsky, E. V.; Buyanov, Yu. I.; Koshelev, V. I., E-mail: koshelev@lhfe.hcei.tsc.ru; Nekrasov, E. S. [Institute of High Current Electronics SB RAS, IHCE SB RAS, Tomsk 634055 (Russian Federation)

2016-03-15

To measure simultaneously two orthogonal components of the electromagnetic field of nano- and subnano-second duration, an antenna array has been developed. The antenna elements of the array are the crossed dipoles of dimension 5 × 5 cm. The arms of the dipoles are connected to the active four-pole devices to compensate the frequency response variations of a short dipole in the frequency band ranging from 0.4 to 4 GHz. The dipoles have superimposed phase centers allowing measuring the polarization structure of the field in different directions. The developed antenna array is the linear one containing four elements. The pattern maximum position is controlled by means of the switched ultrawideband true time delay lines. Discrete steering in seven directions in the range from −40° to +40° has been realized. The error at setting the pattern maximum position is less than 4°. The isolation of the polarization exceeds 29 dB in the direction orthogonal to the array axis and in the whole steering range it exceeds 23 dB. Measurement results of the polarization structure of radiated and scattered pulses with different polarization are presented as well.

Low power arcjet thruster pulse ignition

Science.gov (United States)

Sarmiento, Charles J.; Gruber, Robert P.

1987-01-01

An investigation of the pulse ignition characteristics of a 1 kW class arcjet using an inductive energy storage pulse generator with a pulse width modulated power converter identified several thruster and pulse generator parameters that influence breakdown voltage including pulse generator rate of voltage rise. This work was conducted with an arcjet tested on hydrogen-nitrogen gas mixtures to simulate fully decomposed hydrazine. Over all ranges of thruster and pulser parameters investigated, the mean breakdown voltages varied from 1.4 to 2.7 kV. Ignition tests at elevated thruster temperatures under certain conditions revealed occasional breakdowns to thruster voltages higher than the power converter output voltage. These post breakdown discharges sometimes failed to transition to the lower voltage arc discharge mode and the thruster would not ignite. Under the same conditions, a transition to the arc mode would occur for a subsequent pulse and the thruster would ignite. An automated 11 600 cycle starting and transition to steady state test demonstrated ignition on the first pulse and required application of a second pulse only two times to initiate breakdown.

Repetitive pulsed power technology for inertial-confinement fusion

International Nuclear Information System (INIS)

Prestwich, K.R.; Buttram, M.T.

1983-01-01

The pulsed power requirements for inertial-confinement fusion reactors are defined for ion-beam and laser drivers. Several megajoule beams with 100's of terrawatt peak powers must be delivered to the reactor chamber 1 to 10 times per second. Ion-beam drivers are relatively efficient requiring less energy storage in the pulsed-power system but more time compression in the power flow chain than gas lasers. These high peak powers imply very large numbers of components for conventional pulse-power systems. A new design that significantly reduces the number of components is presented

Review of pulsed rf power generation

International Nuclear Information System (INIS)

Lavine, T.L.

1992-04-01

I am going to talk about pulsed high-power rf generation for normal-conducting electron and positron linacs suitable for applications to high-energy physics in the Next Linear Collider, or NLC. The talk will cover some basic rf system design issues, klystrons and other microwave power sources, rf pulse-compression devices, and test facilities for system-integration studies

Isolated elliptically polarized attosecond soft X-ray with high-brilliance using polarization gating of harmonics from relativistic plasmas at oblique incidence.

Science.gov (United States)

Chen, Zi-Yu; Li, Xiao-Ya; Li, Bo-Yuan; Chen, Min; Liu, Feng

2018-02-19

The production of intense isolated attosecond pulse is a major goal in ultrafast research. Recent advances in high harmonic generation from relativistic plasma mirrors under oblique incidence interactions gave rise to photon-rich attosecond pulses with circular or elliptical polarization. However, to achieve an isolated elliptical attosecond pulse via polarization gating using currently available long driving pulses remains a challenge, because polarization gating of high harmonics from relativistic plasmas is assumed only possible at normal or near-normal incidence. Here we numerically demonstrate a scheme around this problem. We show that via control of plasma dynamics by managing laser polarization, it is possible to gate an intense single attosecond pulse with high ellipticity extending to the soft X-ray regime at oblique incidence. This approach thus paves the way towards a powerful tool enabling high-time-resolution probe of dynamics of chiral systems and magnetic materials with current laser technology.

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

Science.gov (United States)

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

2016-12-01

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

Pulsed Power Applications in High Intensity Proton Rings

CERN Document Server

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

2005-01-01

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

Induction linacs and pulsed power

International Nuclear Information System (INIS)

Caporaso, G.J.

1995-01-01

Progress in electronic power conversion technology is making possible a new class of induction linacs that can operate at extremely high repetition rates. Advances in insulator technology, pulse forming line design and switching may also lead to a new type of high current accelerator with accelerating gradients at least an order of magnitude greater than those attainable today. The evolution of the induction accelerator pulsed power system will be discussed along with some details of these emerging technologies which are at the frontiers of accelerator technology

Proposal of a wide-band mirror polarizer of slow neutrons at a pulsed neutron source

International Nuclear Information System (INIS)

Nikitenko, Yu.V.; Ostanevich, Yu.M.

1992-01-01

The new type wide-band mirror-based neutron polarizer to be operated at a pulsed neutron source is suggested. The idea is to use a movable polarizing mirror system, which, be the incoming beam monochromatized by the time-of-flight, would allow one to tune glancing angles in time so, that the total reflection condition is always fulfilled only for one of the two neutron spin eigenstates. Estimates show, that with the pulsed reactor IBR-2 such polarizer allows one to build a small-angle neutron scattering instrument capable to effectively use the wave-length band from 2 to 15 A. 9 refs.; 1 fig

Laser polarization dependence of proton emission from a thin foil target irradiated by a 70 fs, intense laser pulse

International Nuclear Information System (INIS)

Fukumi, A.; Nishiuchi, M.; Daido, H.; Li, Z.; Sagisaka, A.; Ogura, K.; Orimo, S.; Kado, M.; Hayashi, Y.; Mori, M.; Bulanov, S.V.; Esirkepov, T.; Nemoto, K.; Oishi, Y.; Nayuki, T.; Fujii, T.; Noda, A.; Nakamura, S.

2005-01-01

A study of proton emission from a 3-μm-thick Ta foil target irradiated by p-, s-, and circularly polarized laser pulses with respect to the target plane has been carried out. Protons with energies up to 880 keV were observed in the target normal direction under the irradiation by the p-polarized laser pulse, which yielded the highest efficiency for proton emission. In contrast, s- and circularly polarized laser pulses gave the maximum energies of 610 and 680 keV, respectively. The difference in the maximum energy between the p- and s-polarized cases was associated with the difference between the sheath fields estimated from electron spectra

Laser microprocessing of steel with radially and azimuthally polarized femtosecond vortex pulses

International Nuclear Information System (INIS)

Allegre, O J; Perrie, W; Edwardson, S P; Dearden, G; Watkins, K G

2012-01-01

The use of a liquid-crystal spatial light modulator (SLM) device to convert a linearly polarized femtosecond laser beam into a radially or azimuthally polarized vortex beam is demonstrated. In order to verify the state of polarization at the focal plane, laser induced periodic surface structures (LIPSS) are produced on stainless steel, imprinting the complex vectorial polarization structures and confirming the efficacy of the SLM in producing the desired polarization modes. Stainless steel plates of various thicknesses are micromachined with the radially and azimuthally polarized vortex beams and the resulting cut-outs are analysed. The process efficiency and quality of each mode are compared with those of circular polarization. Radial polarization is confirmed to be the most efficient mode for machining high-aspect-ratio (depth/width > 3) channels thanks to its relatively higher absorptivity. Following our microprocessing tests, liquid-crystal SLMs emerged as a flexible off-the-shelf tool for producing radially and azimuthally polarized beams in existing ultrashort-pulse laser microprocessing systems. (paper)

Nova pulse power system description and status

International Nuclear Information System (INIS)

Holloway, R.W.; Whitham, K.; Merritt, B.T.; Gritton, D.G.; Oicles, J.A.

1981-01-01

The Nova laser system is designed to produce critical data in the nation's inertial confinement fusion effort. It is the world's largest peak power laser and presents various unique pulse power problems. In this paper, pulse power systems for this laser are described, the evolutionary points from prior systems are pointed out, and the current status of the hardware is given

Microwave and pulsed power engineering

International Nuclear Information System (INIS)

Hofer, W.W.

1984-01-01

The Microwave and Pulsed Power Engineering Thrust Area is responsible for developing the short-term and long-term engineering resources required to support the growing microwave and pulsed power engineering requirements of several LLNL Programs. The responsibility of this Thrust Area is to initiate applicable research and development projects and to provide capabilities and facilities to permit engineers involved in these and other programs to make significant contributions. In this section, the principal projects are described: dielectric failure prediction using partial discharge analysis, coating dielectrics to increase surface flashover potential, and the microwave generator experiment

Analyzing power of AGATA triple clusters for gamma-ray linear polarization

Energy Technology Data Exchange (ETDEWEB)

Bizzeti, P.G.; Sona, P.; Melon, B.; Bizzeti-Sona, A.M.; Perego, A. [Universita di Firenze, Dipartimento di Fisica, Firenze (Italy); INFN, Firenze (Italy); Michelagnoli, C.; Lunardi, S.; Mengoni, D.; Recchia, F. [INFN, Padova (Italy); Universita di Padova, Dipartimento di Fisica, Padova (Italy); Bazzacco, D.; Farnea, E.; Menegazzo, R.; Ur, C.A. [INFN, Padova (Italy); De Angelis, G.; Gottardo, A.; Napoli, D.R.; Sahin, E.; Valiente-Dobon, J.J. [Laboratori Nazionali di Legnaro, INFN, Padova (Italy); Gadea, A. [University of Valencia, IFIC, CSIC, Valencia (Spain); Nannini, A. [INFN, Firenze (Italy)

2015-04-01

We have investigated the ability of AGATA triple clusters to measure the linear polarization of gamma rays, exploiting the azimuthal-angle dependence of the Compton scattering differential cross section. To this aim, partially polarized gamma rays have been produced by Coulomb excitation of the first excited state of {sup 104}Pd and {sup 108}Pd, which decay to the ground state by emission of gamma rays of 555.8 keV and 433.9 keV, respectively. Pulse-shape analysis and gamma-ray tracking techniques have been used to determine the position and time sequence of the interaction points inside the germanium crystals. Anisotropies in the detection efficiency have been taken into account using 661.6 keV gammas from a {sup 137}Cs radioactive source. We obtain an average analyzing power of 0.451(34) at 433.9 keV and 0.484(24) at 555.8 keV. (orig.)

Short-pulse optical parametric chirped-pulse amplification for the generation of high-power few-cycle pulses

International Nuclear Information System (INIS)

Major, Zs.; Osterhoff, J.; Hoerlein, R.; Karsch, S.; Fuoloep, J.A.; Krausz, F.; Ludwig-Maximilians Universitaet, Muenchen

2006-01-01

Complete test of publication follows. In the quest for a way to generate ultrashort, high-power, few-cycle laser pulses the discovery of optical parametric amplification (OPA) has opened up to the path towards a completely new regime, well beyond that of conventional laser amplification technology. The main advantage of this parametric amplification process is that it allows for an extremely broad amplification bandwidth compared to any known laser amplifier medium. When combined with the chirped-pulse amplification (CPA) principle (i.e. OPCPA), on one hand pulses of just 10 fs duration and 8 mJ pulse energy have been demonstrated. On the other hand, pulse energies of up to 30 J were also achieved on a different OPCPA system; the pulse duration in this case, however, was 100 fs. In order to combine ultrashort pulse durations (i.e. pulses in the few-cycle regime) with high pulse energies (i.e. in the Joule range) we propose tu pump on OPCPA chain with TW-scale short pulses (100 fs - 1 ps instead of > 100 ps of previous OPCPA systems) delivered by a conventional CPA system. This approach inherently improves the conditions for generating high-power ultrashort pulses using OPCPA in the following ways. Firstly, the short pump pulse duration reduces the necessary stretching factor for the seed pulse, thereby increasing stretching and compression fidelity. Secondly, also due to the shortened pump pulse duration, a much higher contrast is achieved. Finally, the significantly increased pump power makes the use of thinner OPCPA crystals possible, which implies an even broader amplification bandwidth, thereby allowing for even shorter pulses. We carried out theoretical investigations to show the feasibility of such a set-up. Alongside these studies we will also present preliminary experimental results of an OPCPA system pumped by the output of our Ti:Sapphire ATLAS laser, currently delivering 350 mJ in 43 fs. An insight into the planned scaling of this technique to petawatt

Formation of laser-induced periodic surface structures (LIPSS) on tool steel by multiple picosecond laser pulses of different polarizations

Energy Technology Data Exchange (ETDEWEB)

Gregorčič, Peter, E-mail: peter.gregorcic@fs.uni-lj.si [Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, 1000 Ljubljana (Slovenia); Sedlaček, Marko; Podgornik, Bojan [Institute of Metals and Technology, Lepi pot 11, 1000 Ljubljana (Slovenia); Reif, Jürgen [Brandenburgische Technische Universitaet – BTU Cottbus-Senftenberg, Platz der Deutschen Einheit 1, 03046 Cottbus (Germany)

2016-11-30

Highlights: • Low number of differently polarized ps laser pulses is superimposed on tool steel. • Last pulses determine the ripples orientation for single spot and coherent traces. • Previously formed structures are overridden by later incident pulses. • Ripples contrast depends on total exposure, independent on pulses’ polarization. • Weak role of pre-formed structures makes interference scenarios questionable. - Abstract: Laser-induced periodic surface structures (LIPSS) are produced on cold work tool steel by irradiation with a low number of picosecond laser pulses. As expected, the ripples, with a period of about 90% of the laser wavelength, are oriented perpendicular to the laser polarization. Subsequent irradiation with the polarization rotated by 45° or 90° results in a corresponding rotation of the ripples. This is visible already with the first pulse and becomes almost complete – erasing the previous orientation – after as few as three pulses. The phenomenon is not only observed for single-spot irradiation but also for writing long coherent traces. The experimental results strongly defy the role of surface plasmon-polaritons as the predominant key to LIPSS formation.

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

Indian Academy of Sciences (India)

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

Generation of ozone by Ns-width pulsed power

International Nuclear Information System (INIS)

Shimomura, Naoyuki; Wakimoto, Masaya; Shinke, Yosuke; Nagata, Masayoshi; Namihira, Takao; Akiyama, Hidenori

2002-01-01

The demand of ozone will be increasing for wholesome and environment-conscious sterilizations. The generation of ozone using the pulsed power discharge will apply electron accelerations around the head of streamer discharge principally. The breakdown in reactor often limits the efficient generation. Therefore, the pulse shape should be controlled for dimension of the reactor. It is clear that a pulse shortening is one of effective approaches. Pulsed power voltage with ns-width applies for ozone generation. The effects, on concentration and efficiency of generation, of pulse shape, repetition rate of pulse, flow rate of oxygen gas, and dimension and configuration of reactor, are discussed. The dimension and configuration of the reactor are optimized for the pulse width

Pulsed power, ICF, and SDI

International Nuclear Information System (INIS)

Van Devender, J.P.

1986-01-01

Pulsed power technology has been developed over many years for nuclear weapon effects simulation, inertial fusion, and directed energy. Every four years there is a factor of ten increase in power available, and we are now near the 100 TW, couple of million joule (MJ) mark, according to the author. 100 TW is sufficient for studying physics relevant to Inertial Confinement Fusion (ICF) or the Strategic Defense Initiative (SDI). Pulsed power can be viewed as a basic technology for making electron beams, X-rays, and ion beams. Applications include ICF, plasmoid-directed energy weapons, and microwave weapons. The author presents a set of tentative requirements for an effective defense, a concept for deploying the defense, and a strategy for making the transition to a defense-dominated world

Nuclear magnetic resonance in pulse radiolysis. Chemically induced dynamic nuclear polarization

International Nuclear Information System (INIS)

Trifunac, A.D.; Johnson, K.W.; Lowers, R.H.

1976-01-01

Nuclear magnetic resonance and chemically induced dynamic nuclear polarization (CIDNP) were applied to the study of pulse radiolysis. Samples were irradiated with a 3-MeV electron beam from the Argonne Van de Graaff accelerator in an EPR magnet (approximately 4000 G) which had axial holes for beam access. A fast flow system transferred the irradiated solution to the rotating 5-mm NMR sample tube. The NMR spectra of mixtures of sodium acetate and methanol were presented to demonstrate the features of the CIDNP in pulse radiolysis

Interrogation of orbital structure by elliptically polarized intense femtosecond laser pulses

DEFF Research Database (Denmark)

Abu-Samha, Mahmoud; Madsen, Lars Bojer

2011-01-01

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

Comparative studies of efficiency droop in polar and non-polar InGaN quantum wells

International Nuclear Information System (INIS)

Davies, M. J.; Dawson, P.; Hammersley, S.; Zhu, T.; Kappers, M. J.; Humphreys, C. J.; Oliver, R. A.

2016-01-01

We report on a comparative study of efficiency droop in polar and non-polar InGaN quantum well structures at T = 10 K. To ensure that the experiments were carried out with identical carrier densities for any particular excitation power density, we used laser pulses of duration ∼100 fs at a repetition rate of 400 kHz. For both types of structures, efficiency droop was observed to occur for carrier densities of above 7 × 10 11  cm −2  pulse −1 per quantum well; also both structures exhibited similar spectral broadening in the droop regime. These results show that efficiency droop is intrinsic in InGaN quantum wells, whether polar or non-polar, and is a function, specifically, of carrier density.

Advanced Test Accelerator (ATA) pulse power technology development

International Nuclear Information System (INIS)

Reginato, L.L.; Branum, D.; Cook, E.

1981-01-01

The Advanced Test Accelerator (ATA) is a pulsed linear induction accelerator with the following design parameters: 50 MeV, 10 kA, 70 ns, and 1 kHz in a ten-pulse burst. Acceleration is accomplished by means of 190 ferrite-loaded cells, each capable of maintaining a 250 kV voltage pulse for 70 ns across a 1-inch gap. The unique characteristic of this machine is its 1 kHz burst mode capability at very high currents. This paper dscribes the pulse power development program which used the Experimental Test Accelerator (ETA) technology as a starting base. Considerable changes have been made both electrically and mechanically in the pulse power components with special consideration being given to the design to achieve higher reliability. A prototype module which incorporates all the pulse power components has been built and tested for millions of shots. Prototype components and test results are described

Neutron depolarization studies on magnetization process using pulsed polarized neutrons

International Nuclear Information System (INIS)

Mitsuda, Setsuo; Endoh, Yasuo

1985-01-01

Neutron depolarization experiments investigating the magnetization processes have been performed by using pulsed polarized neutrons for the first time. Results on both quenched and annealed ferromagnets of Fe 85 Cr 15 alloy indicate the significant difference in the wavelength dependence of depolarization between them. It also constitutes the experimental demonstration of the theoretical prediction of Halpern and Holstein. (author)

Dynamical model of coherent circularly polarized optical pulse interactions with two-level quantum systems

International Nuclear Information System (INIS)

Slavcheva, G.; Hess, O.

2005-01-01

We propose and develop a method for theoretical description of circularly (elliptically) polarized optical pulse resonant coherent interactions with two-level atoms. The method is based on the time-evolution equations of a two-level quantum system in the presence of a time-dependent dipole perturbation for electric dipole transitions between states with total angular-momentum projection difference (ΔJ z =±1) excited by a circularly polarized electromagnetic field [Feynman et al., J. Appl. Phys. 28, 49 (1957)]. The adopted real-vector representation approach allows for coupling with the vectorial Maxwell's equations for the optical wave propagation and thus the resulting Maxwell pseudospin equations can be numerically solved in the time domain without any approximations. The model permits a more exact study of the ultrafast coherent pulse propagation effects taking into account the vector nature of the electromagnetic field and hence the polarization state of the optical excitation. We demonstrate self-induced transparency effects and formation of polarized solitons. The model represents a qualitative extension of the well-known optical Maxwell-Bloch equations valid for linearly polarized light and a tool for studying coherent quantum control mechanisms

Proposal of a wide-band mirror polarizer of slow neutrons at a pulsed neutron source

International Nuclear Information System (INIS)

Nikitenko, Yu.V.; Ostanevich, Yu.M.

1993-01-01

The new type of wide-band mirror-based neutron polarizer, which is to be operated at a pulsed neutron source, is suggested. The idea is to use a movable polarizing mirror system, which, with the incoming beam monochromatized by the time-of-flight, would allow one to tune glancing angles in time so that the total reflection condition is always fulfilled only for one of the two neutron spin eigenstates. Estimates show that with the pulsed reactor IBR-2 such a polarizer allows one to build a small angle neutron scattering instrument capable of effectively using the wavelength band from 2 A with a rather high luminosity (time-averaged flux at sample position being up to 10 7 n/s/cm -2 ). (orig.)

Generation of a strong attosecond pulse train with an orthogonally polarized two-color laser field

International Nuclear Information System (INIS)

Kim, Chul Min; Kim, I Jong; Nam, Chang Hee

2005-01-01

We theoretically investigate the high-order harmonic generation from a neon atom irradiated by an intense two-color femtosecond laser pulse, in which the fundamental field and its second harmonic are linearly polarized and orthogonal to each other. In contrast to usual high-harmonic generation with linearly polarized fundamental field alone, a very strong and clean high-harmonic spectrum, consisting of both odd and even orders of harmonics, can be generated in the orthogonally polarized two-color laser field with proper selection of the relative phase between the fundamental and second-harmonic fields. In time domain, this results in a strong and regular attosecond pulse train. The origin of these behaviors is elucidated by analyzing semiclassical electron paths and by simulating high-harmonic generation quantum mechanically

Simulation study on cross polarization scattering of ultrashort-pulse electromagnetic waves

International Nuclear Information System (INIS)

Katsuragawa, Naoki; Hojo, Hitoshi; Mase, Atushi

1996-11-01

Simulation study on cross polarization scattering of ultrashort-pulse electromagnetic waves due to magnetic fluctuations is presented. One-dimensional coupled wave equations for the ordinary and extraordinary modes are solved for incident unipolar sub-cycle pulses in an inhomogeneous magnetized plasma. It is shown that the peak frequencies in the frequency-spectral signals of the mode-converted reflected waves are determined from the Bragg resonance condition in the wave numbers of the ordinary mode, the extraordinary mode and the magnetic fluctuations for relatively short-wavelength localized magnetic fluctuations. (author)

Advances in high power linearly polarized fiber laser and its application

Science.gov (United States)

Zhou, Pu; Huang, Long; Ma, Pengfei; Xu, Jiangming; Su, Rongtao; Wang, Xiaolin

2017-10-01

Fiber lasers are now attracting more and more research interest due to their advantages in efficiency, beam quality and flexible operation. Up to now, most of the high power fiber lasers have random distributed polarization state. Linearlypolarized (LP) fiber lasers, which could find wide application potential in coherent detection, coherent/spectral beam combining, nonlinear frequency conversion, have been a research focus in recent years. In this paper, we will present a general review on the achievements of various kinds of high power linear-polarized fiber laser and its application. The recent progress in our group, including power scaling by using power amplifier with different mechanism, high power linearly polarized fiber laser with diversified properties, and various applications of high power linear-polarized fiber laser, are summarized. We have achieved 100 Watt level random distributed feedback fiber laser, kilowatt level continuous-wave (CW) all-fiber polarization-maintained fiber amplifier, 600 watt level average power picosecond polarization-maintained fiber amplifier and 300 watt level average power femtosecond polarization-maintained fiber amplifier. In addition, high power linearly polarized fiber lasers have been successfully applied in 5 kilowatt level coherent beam combining, structured light field and ultrasonic generation.

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

Directory of Open Access Journals (Sweden)

F. Liu

2012-07-01

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

Pulsed power generators using an inductive energy storage system

International Nuclear Information System (INIS)

Akiyama, H.; Sueda, T.; Katschinski, U.; Katsuki, S.; Maeda, S.

1996-01-01

The pulsed power generators using an inductive energy storage system are extremely compact and lightweight in comparison with those using a capacitive energy storage system. The reliable and repetitively operated opening switch is necessary to realize the inductive pulsed power generator. Here, the pulsed power generators using the inductive energy storage system, which have been developed in Kumamoto University, are summarized. copyright 1996 American Institute of Physics

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

OpenAIRE

Kohei Ueno; Eiji Kishikawa; Jitsuo Ohta; Hiroshi Fujioka

2017-01-01

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 6μm. Repeatable p-type doping in N-polar GaN films...

Study of novel plasma devices generated by high power lasers coupled with a micro-pulse power technology

International Nuclear Information System (INIS)

Nishida, A; Chen, Z L; Jin, Z; Kondo, K; Nakagawa, M; Kodama, R; Arima, H; Yoneda, H

2008-01-01

The authors have proposed introducing a micro pulse power technology in high power laser plasma experiments to boost up the return current, resulting in efficiently guiding of energetic electrons. High current pulse power generators with a pulse laser trigger system generate high-density plasma that is well conductor. To efficiently guiding by using a micro pulse power, we estimated parameter of a micro pulse power system that is voltage of rise time, current, charging voltage and capacitance

Comparative studies of efficiency droop in polar and non-polar InGaN quantum wells

Energy Technology Data Exchange (ETDEWEB)

Davies, M. J.; Dawson, P.; Hammersley, S. [School of Physics and Astronomy, Photon Science Institute, University of Manchester, M13 9PL Manchester (United Kingdom); Zhu, T.; Kappers, M. J.; Humphreys, C. J.; Oliver, R. A. [Department of Material Science and Metallurgy, 27 Charles Babbage Road, University of Cambridge, Cambridge CB3 0FS (United Kingdom)

2016-06-20

We report on a comparative study of efficiency droop in polar and non-polar InGaN quantum well structures at T = 10 K. To ensure that the experiments were carried out with identical carrier densities for any particular excitation power density, we used laser pulses of duration ∼100 fs at a repetition rate of 400 kHz. For both types of structures, efficiency droop was observed to occur for carrier densities of above 7 × 10{sup 11 }cm{sup −2 }pulse{sup −1} per quantum well; also both structures exhibited similar spectral broadening in the droop regime. These results show that efficiency droop is intrinsic in InGaN quantum wells, whether polar or non-polar, and is a function, specifically, of carrier density.

Pulse-shaping strategies in short-pulse fiber amplifiers

Energy Technology Data Exchange (ETDEWEB)

Schimpf, Damian Nikolaus

2010-02-09

Ultrashort pulse lasers are an important tool in scientific and industrial applications. However, many applications are demanding higher average powers from these ultrashort pulse sources. This can be achieved by combining direct diode pumping with novel gain media designs. In particular, ultrashort pulse fiber lasers are now delivering average powers in the kW range. However, the design of fiber lasers, producing pulses with high peak-powers, is challenging due to the impact of nonlinear effects. To significantly reduce these detrimental effects in ultrashort pulse fiber amplifers, the combination of chirped pulse amplification (CPA) and large mode area fibers is employed. Using these methods, the pulse energy of fiber lasers has been steadily increasing for the past few years. Recently, a fiber-based CPA-system has been demonstrated which produces pulse energies of around 1 mJ. However, both the stretching and the enlargement of the mode area are limited, and therefore, the impact of nonlinearity is still noticed in systems employing such devices. The aim of this thesis is the analysis of CPA-systems operated beyond the conventional nonlinear limit, which corresponds to accumulated nonlinear phase-shifts around 1 rad. This includes a detailed discussion of the influence of the nonlinear effect self-phase modulation on the output pulse of CPA-systems. An analytical model is presented. Emphasis is placed on the design of novel concepts to control the impact of self-phase modulation. Pulse-shaping is regarded as a powerful tool to accomplish this goal. Novel methods to control the impact of SPM are experimentally demonstrated. The design of these concepts is based on the theoretical findings. Both amplitude- and phase-shaping are studied. Model-based phase-shaping is implemented in a state-of-the-art fiber CPA-system. The influence of the polarization state is also highlighted. Additionally, existing techniques and recent advances are put into context. (orig.)

Pulse-shaping strategies in short-pulse fiber amplifiers

International Nuclear Information System (INIS)

Schimpf, Damian Nikolaus

2010-01-01

Ultrashort pulse lasers are an important tool in scientific and industrial applications. However, many applications are demanding higher average powers from these ultrashort pulse sources. This can be achieved by combining direct diode pumping with novel gain media designs. In particular, ultrashort pulse fiber lasers are now delivering average powers in the kW range. However, the design of fiber lasers, producing pulses with high peak-powers, is challenging due to the impact of nonlinear effects. To significantly reduce these detrimental effects in ultrashort pulse fiber amplifers, the combination of chirped pulse amplification (CPA) and large mode area fibers is employed. Using these methods, the pulse energy of fiber lasers has been steadily increasing for the past few years. Recently, a fiber-based CPA-system has been demonstrated which produces pulse energies of around 1 mJ. However, both the stretching and the enlargement of the mode area are limited, and therefore, the impact of nonlinearity is still noticed in systems employing such devices. The aim of this thesis is the analysis of CPA-systems operated beyond the conventional nonlinear limit, which corresponds to accumulated nonlinear phase-shifts around 1 rad. This includes a detailed discussion of the influence of the nonlinear effect self-phase modulation on the output pulse of CPA-systems. An analytical model is presented. Emphasis is placed on the design of novel concepts to control the impact of self-phase modulation. Pulse-shaping is regarded as a powerful tool to accomplish this goal. Novel methods to control the impact of SPM are experimentally demonstrated. The design of these concepts is based on the theoretical findings. Both amplitude- and phase-shaping are studied. Model-based phase-shaping is implemented in a state-of-the-art fiber CPA-system. The influence of the polarization state is also highlighted. Additionally, existing techniques and recent advances are put into context. (orig.)

Pulsed corona generation using a diode-based pulsed power generator

Science.gov (United States)

Pemen, A. J. M.; Grekhov, I. V.; van Heesch, E. J. M.; Yan, K.; Nair, S. A.; Korotkov, S. V.

2003-10-01

Pulsed plasma techniques serve a wide range of unconventional processes, such as gas and water processing, hydrogen production, and nanotechnology. Extending research on promising applications, such as pulsed corona processing, depends to a great extent on the availability of reliable, efficient and repetitive high-voltage pulsed power technology. Heavy-duty opening switches are the most critical components in high-voltage pulsed power systems with inductive energy storage. At the Ioffe Institute, an unconventional switching mechanism has been found, based on the fast recovery process in a diode. This article discusses the application of such a "drift-step-recovery-diode" for pulsed corona plasma generation. The principle of the diode-based nanosecond high-voltage generator will be discussed. The generator will be coupled to a corona reactor via a transmission-line transformer. The advantages of this concept, such as easy voltage transformation, load matching, switch protection and easy coupling with a dc bias voltage, will be discussed. The developed circuit is tested at both a resistive load and various corona reactors. Methods to optimize the energy transfer to a corona reactor have been evaluated. The impedance matching between the pulse generator and corona reactor can be significantly improved by using a dc bias voltage. At good matching, the corona energy increases and less energy reflects back to the generator. Matching can also be slightly improved by increasing the temperature in the corona reactor. More effective is to reduce the reactor pressure.

Pulsed Electrical Spin Injection into InGaAs Quantum Dots: Studies of the Electroluminescence Polarization Dynamics

International Nuclear Information System (INIS)

Asshoff, P.; Loeffler, W.; Fluegge, H.; Zimmer, J.; Mueller, J.; Westenfelder, B.; Hu, D. Z.; Schaadt, D. M.; Kalt, H.; Hetterich, M.

2010-01-01

We present time-resolved studies of the spin polarization dynamics during and after initialization through pulsed electrical spin injection into InGaAs quantum dots embedded in a p-i-n-type spin-injection light-emitting diode. Experiments are performed with pulse widths in the nanosecond range and a time-resolved single photon counting setup is used to detect the subsequent electroluminescence. We find evidence that the achieved spin polarization shows an unexpected temporal behavior, attributed mainly to many-carrier and non-equilibrium effects in the device.

Pulse power requirements for large aperture optical switches based on plasma electrode Pockels cells

International Nuclear Information System (INIS)

Rhodes, M.A.; Taylor, J.

1992-06-01

We discuss very large-aperture optical switches (greater than 30 x 30 cm) as an enabling technology for inertial confinement fusion drivers based on multipass laser amplifiers. Large-scale laser fusion drivers such as the Nova laser have been based on single-pass amplifier designs in part because of the unavailability of a suitable large-aperture switch. We are developing an optical switch based on a Pockels cell employing plasma-electrodes. A plasma-electrode Pockels cell (PEPC) is a longitudinal-mode Pockels cell in which a plasma discharge is formed on each side of an electro-optic crystal (typically KDP or deuterated KDP, often designated KD*P). The plasmas formed on either side of the crystal act as transparent electrodes for a switching-pulse and are intended to allow uniform charging of the entire crystal. The switching-pulse is a nominally rectangular high-voltage pulse equal to the half-wave voltage V x ( 8 kV for KD*P or 17 kV for KDP) and is applied across the crystal via the plasma-electrodes. When the crystal is charged to V x , the polarization of an incoming, linearly polarized, laser beam is rotated by 90 degree. When used in conjunction with an appropriate, passive polarizer, an optical switch is thus realized. A switch with a clear aperture of 37 x 37 cm is now in construction for the Beamlet laser which will serve as a test bed for this switch as well as other technologies required for an advanced NOVA laser design. In this paper, we discuss the unique power electronics requirements of PEPC optical switches

Pulsed power bibliography. Volume 1: Indices

Science.gov (United States)

Bemesderfer, J.; Druce, R. L.; Frantz, B.; Guenther, A. H.; Kristiansen, M.; Oloughlin, J. P.; Pendleton, W. K.

1983-08-01

Pulsed power and high-voltage technologies are playing an ever increasing role in weapons' effects simulation, fusion power research, power distribution, materials processing and medical research. It is a rapidly expanding field of applied physics as evidenced by the growth in published literature. Three years ago, the Air Force Weapons Laboratory (AFWL) initiated a project to compile a computerized data base of pulsed power research papers. The data base is stored on our IBM System 2000. This AFWL Technical Report is the first release of the bibliography to date. It contains about 2,500 full bibliographic citations, original sources, availability, key words and abstract. There are three indices: Subject, Personal Author, and Corporate Author. There are 30 main subject headings, from Breakdown Studies to Switching. The indices are contained in Volume 1.

Carrier and polarization dynamics in monolayer MoS2: temperature and power dependence

Science.gov (United States)

Urbaszek, Bernhard; Lagarde, D.; Bouet, L.; Amand, T.; Marie, X.; Zhu, C. R.; Liu, B. L.; Tan, P. H.

2014-03-01

In monolayer (ML) MoS2 optical transitions across the direct bandgap are governed by chiral selection rules, allowing optical k-valley initialization. Here we present the first time resolved photoluminescence (PL) polarization measurements in MoS2 MLs, providing vital information on the electron valley dynamics. Using quasi-resonant excitation of the A-exciton transitions, we can infer that the PL decays within τ ~= 4ps. The PL polarization of Pc ~ 60 % remains nearly constant in time for experiments from 4K - 300K, a necessary condition for the success of future Valley Hall experiments. τ does not vary significantly over this temperature range. This is surprising when considering the decrease of Pc in continuous wave experiments when going from 4K to 300K reported in the literature. By tuning the laser following the shift of the A-exciton resonance with temperature we are able to recover at 300K ~ 80 % of the polarization observed at 4K. For pulsed laser excitation, we observe a decrease of Pc with increasing laser power at all temperatures.

Determination of modeling parameters for power IGBTs under pulsed power conditions

Energy Technology Data Exchange (ETDEWEB)

Dale, Gregory E [Los Alamos National Laboratory; Van Gordon, Jim A [U. OF MISSOURI; Kovaleski, Scott D [U. OF MISSOURI

2010-01-01

While the power insulated gate bipolar transistor (IGRT) is used in many applications, it is not well characterized under pulsed power conditions. This makes the IGBT difficult to model for solid state pulsed power applications. The Oziemkiewicz implementation of the Hefner model is utilized to simulate IGBTs in some circuit simulation software packages. However, the seventeen parameters necessary for the Oziemkiewicz implementation must be known for the conditions under which the device will be operating. Using both experimental and simulated data with a least squares curve fitting technique, the parameters necessary to model a given IGBT can be determined. This paper presents two sets of these seventeen parameters that correspond to two different models of power IGBTs. Specifically, these parameters correspond to voltages up to 3.5 kV, currents up to 750 A, and pulse widths up to 10 {micro}s. Additionally, comparisons of the experimental and simulated data will be presented.

Radially polarized and passively Q-switched Yb-doped fiber laser based on intracavity birefringent mode discrimination

Science.gov (United States)

Sun, Xuehuan; Wu, Yongxiao; Chen, Sanbin; Li, Jianlang

2018-05-01

In this paper, we demonstrated a passive Q-switched ytterbium-doped fiber laser with radially polarized beam emission by using a c-cut YVO4 birefringent crystal as the intracavity polarization discriminator, and a Cr4+:YAG crystal as the saturable absorber and output coupler. The maximum averaged laser power reached 3.89 W with a high slope efficiency of 66.5%. The laser pulse had a peak power of 161 W, 160 ns duration, and 151 kHz repetition rate at the absorbed pump power of 6.48 W. Such a radially polarized pulse would facilitate numerous applications.

Progress of high power and long pulse ECRH system in EAST

International Nuclear Information System (INIS)

Wang, Xiaojie; Liu, Fukun; Shan, Jiafang; Xu, Handong; DajunWu; Li, Bo; Wei, Wei; Zhang, Jian; Huang, Yiyun; Tang, Yunying; Xu, Weiye; Hu, Huaichuan; Wang, Jian; Xu, Li; Zhang, Liyuan; Feng, Jianqiang

2015-01-01

Highlights: • The design and the status of the 140 GHz/4 MW/1000 s ECRH system on EAST tokamak is described in detail. • Two of the four gyrotrons are tested in factory. • The transmission line and the equatorial launcher for the first 2 MW system are ready for installation. • Series tests have been carried out for the most critical elements for the real-time launcher. • The auxiliary system includes the water cooling system, the HVPS system, the vacuum system have been installed and tested. - Abstract: In accordance with the long pulse objectives of the Experimental Advanced Superconducting Tokamak (EAST), an electron cyclotron resonance heating (ECRH) system with the feature of 4 MW power for a pulse length up to 1000 s at 140 GHz, using second harmonic of the extraordinary mode (X2) is presently under construction at the institute of plasma physics, Chinese academy of sciences (ASIPP). The missions of the system are to provide central heating, current drive, plasma profile tailoring and control of magneto-hydrodynamic (MHD) instabilities. The continuous wave (CW) power is transmitted from the gyrotrons to EAST via low-loss evacuated waveguide transmission lines. Considering the diverse applications of the EC system, the front steering launcher is designed to inject four individually steered beams across nearly the entire plasma cross section. The beam's launch angles can be continuously varied with the optimized scanning range of over 30° in poloidal direction and ±25° in toroidal, as well as the polarization will be adjusted during the discharge by the orientations of a pair of polarizers in the transmission line to maintain the highest absorption for different operational scenarios. The commissioning of the first 2 MW system will be commenced in the end of 2014.

Pulsed power research at the institute of fluid physics

International Nuclear Information System (INIS)

Deng Jianjun; Shi Jinshui; Cao Kefeng; Xie Weiping; Zhang Linwen; Wang Meng

2009-01-01

The Institute of Fluid Physics was the earliest institution in China to engage in pulsed power research, covering areas such as the development of high power switches, linear induction accelerators, facilities for Z-pinch studies, pulsed X-ray machines, explosive magnetic compression technology, rep-rate pulsed power generation, time resolved diagnostic technology, and so on. The newly built Dragon-I facility (20 MeV, 2.5kA, 80 ns), currently the most advanced linear induction accelerator in the world, is described. The status of the Primary Test Stand (PTS, 8-10 MA, 130ns) for Z-pinch studies that is still under construction is also reported. The PTS consists of 24 modules based on the Marx generator-water PFL (pulse forming line) technology. The single module prototype has been tested successfully. Other progress on the rep-rate pulsed power generator, linear transfer driver, and time resolved diagnostic technology is also presented. (authors)

Triple Pulse Tester - Efficient Power Loss Characterization of Power Modules

DEFF Research Database (Denmark)

Trintis, Ionut; Poulsen, Thomas; Beczkowski, Szymon

2015-01-01

In this paper the triple pulse testing method and circuit for power loss characterization of power modules is introduced. The proposed test platform is able to accurately characterize both the switching and conduction losses of power modules in a single automated process. A configuration of a half...

The energy and temporal characteristics of orthogonal polarized waves generated by a transversely-excited pulsed CO/sub 2/ laser

Energy Technology Data Exchange (ETDEWEB)

Bertel, I.M.; Churakov, V.V.; Petukhov, V.O.; Prokopov, A.P.; Trushin, S.A.; Voitovich, A.P.

1980-01-01

The competition of orthogonally-polarized waves with various differences in the wave Q-factors and active medium pressures is studied. The possibility of controlling the parameters of a pulsed CO/sub 2/ laser by changing the value of the amplitude anisotropy of the cavity is demonstrated. The duration of the emission pulse for one of two orthogonal polarizations was reduced by virtually 50%.

Solid-state resistor for pulsed power machines

Science.gov (United States)

Stoltzfus, Brian; Savage, Mark E.; Hutsel, Brian Thomas; Fowler, William E.; MacRunnels, Keven Alan; Justus, David; Stygar, William A.

2016-12-06

A flexible solid-state resistor comprises a string of ceramic resistors that can be used to charge the capacitors of a linear transformer driver (LTD) used in a pulsed power machine. The solid-state resistor is able to absorb the energy of a switch prefire, thereby limiting LTD cavity damage, yet has a sufficiently low RC charge time to allow the capacitor to be recharged without disrupting the operation of the pulsed power machine.

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

Science.gov (United States)

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

2014-11-28

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

High-power laser diodes with high polarization purity

Science.gov (United States)

Rosenkrantz, Etai; Yanson, Dan; Peleg, Ophir; Blonder, Moshe; Rappaport, Noam; Klumel, Genady

2017-02-01

Fiber-coupled laser diode modules employ power scaling of single emitters for fiber laser pumping. To this end, techniques such as geometrical, spectral and polarization beam combining (PBC) are used. For PBC, linear polarization with high degree of purity is important, as any non-perfectly polarized light leads to losses and heating. Furthermore, PBC is typically performed in a collimated portion of the beams, which also cancels the angular dependence of the PBC element, e.g., beam-splitter. However, we discovered that single emitters have variable degrees of polarization, which depends both on the operating current and far-field divergence. We present data to show angle-resolved polarization measurements that correlate with the ignition of high-order modes in the slow-axis emission of the emitter. We demonstrate that the ultimate laser brightness includes not only the standard parameters such as power, emitting area and beam divergence, but also the degree of polarization (DoP), which is a strong function of the latter. Improved slow-axis divergence, therefore, contributes not only to high brightness but also high beam combining efficiency through polarization.

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

Energy Technology Data Exchange (ETDEWEB)

Szarmes, E.B.; Madey, J.M.J. [Duke Univ., Durham, NC (United States)

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.

Inductive-pulsed power supplying system for a betatron electromagnet

International Nuclear Information System (INIS)

Otrubyannikov, Yu.A.; Safronov, A.S.

1984-01-01

Circuit of producing quasitriangular current pulses designed for the pulsed power supply system of betatron electromagnet is described. Introduction of additional winding into electromagnet provides circuit galvanic isolation, artificial commutation of basic circuit thyristors and inductive power input to the winding during thyristor commutation. The considered system is used for excitation of betatron electromagnet up to 18 MeV. Magnetic field energy equals 1100 Y. The maximal voltage in energy storage capacitor - 4.8 kV. Current amplitude in basic winding - 335 A. The number of loops in basic winding equals 80, in additional one - 32. Current pulse duration in electromagnet-3.8 ms. The system provides operation with controlled current pulse frequency from 0 up to 150 Hz. The maximal consumption power - 18 kW

A pulse programmable parahydrogen polarizer using a tunable electromagnet and dual channel NMR spectrometer

Science.gov (United States)

Coffey, Aaron M.; Shchepin, Roman V.; Feng, Bibo; Colon, Raul D.; Wilkens, Ken; Waddell, Kevin W.; Chekmenev, Eduard Y.

2017-11-01

Applications of parahydrogen induced polarization (PHIP) often warrant conversion of the chemically-synthesized singlet-state spin order into net heteronuclear magnetization. In order to obtain optimal yields from the overall hyperpolarization process, catalytic hydrogenation must be tightly synchronized to subsequent radiofrequency (RF) transformations of spin order. Commercial NMR consoles are designed to synchronize applied waves on multiple channels and consequently are well-suited as controllers for these types of hyperpolarization experiments that require tight coordination of RF and non-RF events. Described here is a PHIP instrument interfaced to a portable NMR console operating with a static field electromagnet in the milliTesla regime. In addition to providing comprehensive control over chemistry and RF events, this setup condenses the PHIP protocol into a pulse-program that in turn can be readily shared in the manner of traditional pulse sequences. In this device, a TTL multiplexer was constructed to convert spectrometer TTL outputs into 24 VDC signals. These signals then activated solenoid valves to control chemical shuttling and reactivity in PHIP experiments. Consolidating these steps in a pulse-programming environment speeded calibration and improved quality assurance by enabling the B0/B1 fields to be tuned based on the direct acquisition of thermally polarized and hyperpolarized NMR signals. Performance was tested on the parahydrogen addition product of 2-hydroxyethyl propionate-1-13C-d3, where the 13C polarization was estimated to be P13C = 20 ± 2.5% corresponding to 13C signal enhancement approximately 25 million-fold at 9.1 mT or approximately 77,000-fold 13C enhancement at 3 T with respect to thermally induced polarization at room temperature.

Pulsed power performance of PBFA Z

International Nuclear Information System (INIS)

Spielman, R.B.; Stygar, W.A.; Seamen, J.F.

1997-01-01

PBFA Z is a new 60-TW/5-MJ electrical driver located at Sandia National Laboratories. The authors use PBFA Z to drive z pinches. The pulsed power design of PBFA Z is based on conventional single-pulse Marx generator, water-line pulse-forming technology used on the earlier Saturn and PBFA II accelerators. PBFA Z stores 11.4 MJ in its 36 Marx generators, couples 5 MJ in a 60-TW/105-ns pulse to the output water transmission lines, and delivers 3.0 MJ and 50 TW of electrical energy to the z-pinch load. Depending on the initial load inductance and the implosion time, the authors attain peak currents of 16-20 MA with a rise time of 105 ns. Current is fed to the z-pinch load through self magnetically-insulated transmission lines (MITLs). Peak electric fields in the MITLs exceed 2 MV/cm. The current from the four independent conical-disk MITLs is combined together in a double post-hole vacuum convolute with an efficiency greater than 95%. The authors achieved x-ray powers of 200 TW and x-ray energies of 1.9 MJ from tungsten wire-array z-pinch loads

Pulsed Polarization-Based NOx Sensors of YSZ Films Produced by the Aerosol Deposition Method and by Screen-Printing.

Science.gov (United States)

Exner, Jörg; Albrecht, Gaby; Schönauer-Kamin, Daniela; Kita, Jaroslaw; Moos, Ralf

2017-07-26

The pulsed polarization technique on solid electrolytes is based on alternating potential pulses interrupted by self-discharge pauses. Since even small concentrations of nitrogen oxides (NO x ) in the ppm range significantly change the polarization and discharge behavior, pulsed polarization sensors are well suited to measure low amounts of NO x . In contrast to all previous investigations, planar pulsed polarization sensors were built using an electrolyte thick film and platinum interdigital electrodes on alumina substrates. Two different sensor layouts were investigated, the first with buried Pt electrodes under the electrolyte and the second one with conventional overlying Pt electrodes. Electrolyte thick films were either formed by aerosol deposition or by screen-printing, therefore exhibiting a dense or porous microstructure, respectively. For screen-printed electrolytes, the influence of the electrolyte resistance on the NO x sensing ability was investigated as well. Sensors with buried electrodes showed little to no response even at higher NO x concentrations, in good agreement with the intended sensor mechanism. Electrolyte films with overlying electrodes, however, allowed the quantitative detection of NO x . In particular, aerosol deposited electrolytes exhibited high sensitivities with a sensor output signal Δ U of 50 mV and 75 mV for 3 ppm of NO and NO₂, respectively. For screen-printed electrolytes, a clear trend indicated a decrease in sensitivity with increased electrolyte resistance.

Beams 92: Proceedings. Volume 1: Invited papers, pulsed power

Energy Technology Data Exchange (ETDEWEB)

Mosher, D.; Cooperstein, G. [eds.] [Naval Research Lab., Washington, DC (United States)

1993-12-31

This report contains papers on the following topics: Ion beam papers; electron beam, bremsstrahlung, and diagnostics papers; radiating Z- pinch papers; microwave papers; electron laser papers; advanced accelerator papers; beam and pulsed power applications papers; pulsed power papers; and these papers have been indexed separately elsewhere.

Classical-trajectory simulation of accelerating neutral atoms with polarized intense laser pulses

Science.gov (United States)

Xia, Q. Z.; Fu, L. B.; Liu, J.

2013-03-01

In the present paper, we perform the classical trajectory Monte Carlo simulation of the complex dynamics of accelerating neutral atoms with linearly or circularly polarized intense laser pulses. Our simulations involve the ion motion as well as the tunneling ionization and the scattering dynamics of valence electron in the combined Coulomb and electromagnetic fields, for both helium (He) and magnesium (Mg). We show that for He atoms, only linearly polarized lasers can effectively accelerate the atoms, while for Mg atoms, we find that both linearly and circularly polarized lasers can successively accelerate the atoms. The underlying mechanism is discussed and the subcycle dynamics of accelerating trajectories is investigated. We have compared our theoretical results with a recent experiment [Eichmann Nature (London)NATUAS0028-083610.1038/nature08481 461, 1261 (2009)].

Steady state ion acceleration by a circularly polarized laser pulse

International Nuclear Information System (INIS)

Zhang Xiaomei; Shen Baifei; Cang Yu; Li Xuemei; Jin Zhangying; Wang Fengchao

2007-01-01

The steady state ion acceleration at the front of a cold solid target by a circularly polarized flat-top laser pulse is studied with one-dimensional particle-in-cell (PIC) simulation. A model that ions are reflected by a steady laser-driven piston is used by comparing with the electrostatic shock acceleration. A stable profile with a double-flat-top structure in phase space forms after ions enter the undisturbed region of the target with a constant velocity

Variable Power, Short Microwave Pulses Generation using a CW Magnetron

Directory of Open Access Journals (Sweden)

CIUPA, R.

2011-05-01

Full Text Available Fine control of microwave power radiation in medical and scientific applications is a challenging task. Since a commercial Continuous Wave (CW magnetron is the most inexpensive microwave device available today on the market, it becomes the best candidate for a microwave power generator used in medical diathermy and hyperthermia treatments or high efficiency chemical reactions using microwave reactors as well. This article presents a new method for driving a CW magnetron with short pulses, using a modified commercial Zero Voltage Switching (ZVS inverter, software driven by a custom embedded system. The microwave power generator designed with this method can be programmed for output microwave pulses down to 1% of the magnetron's power and allows microwave low frequency pulse modulation in the range of human brain electrical activity, intended for medical applications. Microwave output power continuous control is also possible with the magnetron running in the oscillating area, using a dual frequency Pulse Width Modulation (PWM, where the low frequency PWM pulse is modulating a higher resonant frequency required by the ZVS inverter's transformer. The method presented allows a continuous control of both power and energy (duty-cycle at the inverter's output.

Maskless patterning by pulsed-power plasma printing

NARCIS (Netherlands)

Huiskamp, T.; Brok, W.J.M.; Stevens, A.A.E.; Heesch, van E.J.M.; Pemen, A.J.M.

2012-01-01

In this paper, pulsed-power technology was applied to plasma printing, which is a maskless plasma patterning solution that is being developed for the fabrication process of printed electronics. A high-voltage pulse source was developed and applied to a high-speed plasma printer to improve the speed

Magnetic field effects on ultrafast lattice compression dynamics of Si(111) crystal when excited by linearly-polarized femtosecond laser pulses

Science.gov (United States)

Hatanaka, Koji; Odaka, Hideho; Ono, Kimitoshi; Fukumura, Hiroshi

2007-03-01

Time-resolved X-ray diffraction measurements of Si (111) single crystal are performed when excited by linearly-polarized femtosecond laser pulses (780 nm, 260 fs, negatively-chirped, 1 kHz) under a magnetic field (0.47 T). Laser fluence on the sample surface is 40 mJ/cm^2, which is enough lower than the ablation threshold at 200 mJ/cm^2. Probing X-ray pulses of iron characteristic X-ray lines at 0.193604 and 0.193998 nm are generated by focusing femtosecond laser pulses onto audio-cassette tapes in air. Linearly-polarized femtosecond laser pulse irradiation onto Si(111) crystal surface induces transient lattice compression in the picosecond time range, which is confirmed by transient angle shift of X-ray diffraction to higher angles. Little difference of compression dynamics is observed when the laser polarization is changed from p to s-pol. without a magnetic field. On the other hand, under a magnetic field, the lattice compression dynamics changes when the laser is p-polarized which is vertical to the magnetic field vector. These results may be assigned to photo-carrier formation and energy-band distortion.

All solid state pulsed power system for water discharge

OpenAIRE

Sakugawa, Takashi; Yamaguchi, Takahiro; Yamamoto, Kunihiro; Kiyan, Tsuyoshi; Namihira, Takao; Katsuki, Sunao; Akiyama, Hidenori; サクガワ, タカシ; ヤマグチ, タカヒロ; ヤマモト, クニヒロ; キヤン, ツヨシ; ナミヒラ, タカオ; カツキ, スナオ; アキヤマ, ヒデノリ; 佐久川, 貴志

2005-01-01

Pulsed power has been used to produce non-thermal plasmas in gases that generate a high electric field at the tip of streamer discharges, where high energy electrons, free radicals, and ozone are produced. Recently, all solid state pulsed power generators, which are operated with high repetition rate, long lifetime and high reliability, have been developed for industrial applications, such as high repetition rate pulsed gas lasers, high energy density plasma (EUV sources) and water discharges...

Polarized Raman study on the lattice structure of BiFeO3 films prepared by pulsed laser deposition

KAUST Repository

Yang, Yang; Yao, Yingbang; Zhang, Q.; Zhang, Xixiang

2014-01-01

Polarized Raman spectroscopy was used to study the lattice structure of BiFeO3 films on different substrates prepared by pulsed laser deposition. Interestingly, the Raman spectra of BiFeO3 films exhibit distinct polarization dependences

Influence of a falling edge on high power microwave pulse combination

Science.gov (United States)

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.

Pulsed power systems for inertial confinement fusion

International Nuclear Information System (INIS)

VanDevender, J.P.

1979-01-01

Sandis's Particle Beam Fusion Program is investigating pulsed electron and light ion beam accelerators with the goal of demonstrating the practical application of such drivers as igniters in inertial confinement fusion (ICF) reactors. The power and energy requirements for net energy gain are 10 14 to 10 15 W and 1 to 10 MJ. Recent advances in pulsed power and power flow technologies permit suitable accelerators to be built. The first accelerator of this new generation is PBFA I. It operates at 2 MV, 15 MA, 30 TW for 35 ns and is scheduled for completion in June 1980. The principles of this new accelerator technology and their application to ICF will be presented

Compulsator, a high power compensated pulsed alternator

International Nuclear Information System (INIS)

Weldon, W.F.; Bird, W.L.; Driga, M.D.; Rylander, H.G.; Tolk, K.M.; Woodson, H.H.

1983-01-01

This chapter describes a pulsed power supply utilizing inertial energy storage as a possible replacement for large capacitor banks. The compulsator overcomes many of the limitations of the pulsed homopolar generators previously developed by the Center for Electromechanics and elsewhere in that it offers high voltage (10's of kV) and consequently higher pulse rise times, is self commutating, and offers the possibility of generating repetitive pulses. The compulsator converts rotational inertial energy directly into electrical energy utilizing the principles of both magnetic induction and flux compression. The theory of operation, a prototype compulsator design, and advanced compulsator designs are discussed

Computational efficiency improvement with Wigner rotation technique in studying atoms in intense few-cycle circularly polarized pulses

International Nuclear Information System (INIS)

Yuan, Minghu; Feng, Liqiang; Lü, Rui; Chu, Tianshu

2014-01-01

We show that by introducing Wigner rotation technique into the solution of time-dependent Schrödinger equation in length gauge, computational efficiency can be greatly improved in describing atoms in intense few-cycle circularly polarized laser pulses. The methodology with Wigner rotation technique underlying our openMP parallel computational code for circularly polarized laser pulses is described. Results of test calculations to investigate the scaling property of the computational code with the number of the electronic angular basis function l as well as the strong field phenomena are presented and discussed for the hydrogen atom

Production and investigation of pulsed polarized electron beams at the S-DALINAC; Erzeugung und Untersuchung gepulster polarisierter Elektronenstrahlen am S-DALINAC

Energy Technology Data Exchange (ETDEWEB)

Wagner, Markus

2013-08-15

power and on the center wavelength λ{sub 0}. To reduce these effects a free laser beam transfer has been build up, too. By using a Piezo mirror and a developed feedback control system it was possible to achieve a positional accuracy of <10 μm at a control frequency of 2 Hz over 66 h at the location of the cathode. With an additionally installed narrow slit the bunch length could be characterized with a resolution of (7.0±3.5) ps. Here, a phase jitter of the electron beam of 2.2 ps at a measuring time of 30 min was determined. Due to the run time differences of the laser beam during transfer, which are caused by the feedback control system, one more negligible jitter of 1.6 fs appeared. The measurements indicate an additional mode inside the chopper cavity. This changes the position of phase of the laser pulse with respect to the chopper state. This effect was measured with the 780 nm laser-diode and to be between 30 ps and to 80 ps. From experimental results, that was modeled and reproduced by a simulation, a genuine bunch length of (50.0±0.2) ps could be determined. The measurements of the longitudinal (bunch length) and of the transverse (beam diameter) beam profile have shown space-charge effects already at a bunch charge of 1 fC. To compensate the pulse broadening in the 50 m long fiber, a pulse compressor was built. With the aid of it and the usage of a bulk GaAs photo-cathode the lengths of the electron bunch could be varied between 30 ps to 80 ps. The intensity and polarization of the electron bunches from a bulk- and a superlattice GaAs cathode were measured with good phase resolution using the chopper-slit-method. In the case of bulk cathode, an average polarization of (31.0±3.5)% and a peak polarization of (49.1±5.6)% was yielded. In the case of superlattice cathode an average polarization of only (38.4±4.4)% and a peak polarization of (65.7±7.5)% were achieved. The new modell that was developed in this work takes into account not only intensity

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

International Nuclear Information System (INIS)

Nantista, C.

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 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)

Extension of supercontinuum spectrum generated in photonic crystal fiber by using chirped femtosecond pulses

Science.gov (United States)

Vengelis, Julius; Jarutis, Vygandas; Sirutkaitis, Valdas

2017-08-01

We present results of experimental and numerical investigation of supercontinuum generation in polarization maintaining photonic crystal fiber (PCF) using chirped femtosecond pulses. The initial unchirped pump pulse source was a mode-locked Yb:KGW laser generating 52 nJ energy 110 fs duration pulses at 1030 nm with 76 MHz repetition rate. The nonlinear medium was a 32 cm long polarization maintaining PCF manufactured by NKT Photonics A/S. We demonstrated the influence of pump pulse chirp on spectral characteristics of supercontinuum. We showed that by chirping pump pulses positively or negatively one can obtain broader supercontinuum spectrum than in case of unchirped pump pulses at the same peak power. Moreover, the extension can be controlled by changing the amount of pump pulse chirp. In our case the supercontinuum spectrum width was extended by up to 115 nm (at maximum chirp value of +10500 fs2 that we could achieve in our setup) compared to the case of unchirped pump at the same peak power.

Pulsed power accelerator for material physics experiments

Directory of Open Access Journals (Sweden)

D. B. Reisman

2015-09-01

Full Text Available We have developed the design of Thor: a pulsed power accelerator that delivers a precisely shaped current pulse with a peak value as high as 7 MA to a strip-line load. The peak magnetic pressure achieved within a 1-cm-wide load is as high as 100 GPa. Thor is powered by as many as 288 decoupled and transit-time isolated bricks. Each brick consists of a single switch and two capacitors connected electrically in series. The bricks can be individually triggered to achieve a high degree of current pulse tailoring. Because the accelerator is impedance matched throughout, capacitor energy is delivered to the strip-line load with an efficiency as high as 50%. We used an iterative finite element method (FEM, circuit, and magnetohydrodynamic simulations to develop an optimized accelerator design. When powered by 96 bricks, Thor delivers as much as 4.1 MA to a load, and achieves peak magnetic pressures as high as 65 GPa. When powered by 288 bricks, Thor delivers as much as 6.9 MA to a load, and achieves magnetic pressures as high as 170 GPa. We have developed an algebraic calculational procedure that uses the single brick basis function to determine the brick-triggering sequence necessary to generate a highly tailored current pulse time history for shockless loading of samples. Thor will drive a wide variety of magnetically driven shockless ramp compression, shockless flyer plate, shock-ramp, equation of state, material strength, phase transition, and other advanced material physics experiments.

Generation of polarization-entangled photon pairs in a cascade of two type-I crystals pumped by femtosecond pulses

International Nuclear Information System (INIS)

Nambu, Yoshihiro; Usami, Koji; Tsuda, Yoshiyuki; Matsumoto, Keiji; Nakamura, Kazuo

2002-01-01

We report the generation of polarization-entangled photons by femtosecond-pulse-pumped spontaneous parametric down-conversion in a cascade of two type-I crystals. Highly entangled pulsed states were obtained by introducing a temporal delay between the two orthogonal polarization components of the pump field. They exhibited high-visibility quantum interference and a large concurrence value, without the need of postselection using narrow-bandwidth spectral filters. The results are well explained by the theory which incorporates the space-time dependence of interfering two-photon amplitudes if dispersion and birefringence in the crystals are appropriately taken into account. Such a pulsed entangled photon well localized in time domain is useful for various quantum communication experiments, such as quantum cryptography and quantum teleportation

New developments of plasma science with pulsed power technology

International Nuclear Information System (INIS)

Kamada, Keiichi; Ozaki, Tetsuo

2010-03-01

In this proceedings, the papers presented at the symposium on “New developments of Plasma Science with Pulsed Power Technology” held at National Institute for Fusion Science on March 5-6, 2009 are collected. The papers reflect the present status and recent progress in the experimental and theoretical works on plasma science using pulsed power technology. (author)

Solid-state fast voltage compensator for pulsed power applications requiring constant AC power consumption

CERN Document Server

Magallanes, Francisco Cabaleiro; Viarouge, Philippe; Cros, Jérôme

2015-01-01

This paper proposes a novel topological solution for pulsed power converters based on capacitor-discharge topologies, integrating a Fast Voltage Compensator which allows an operation at constant power consumption from the utility grid. This solution has been retained as a possible candidate for the CLIC project under study at CERN, which requires more than a thousand synchronously-operated klystron modulators producing a total pulsed power of almost 40 GW. The proposed Fast Voltage Compensator is integrated in the modulator such that it only has to treat the capacitor charger current and a fraction of the charging voltage, meaning that its dimensioning power and cost are minimized. This topology can be used to improve the AC power quality of any pulsed converters based on capacitor-discharge concept. A prototype has been built and exploited to validate the operating principle and demonstrate the benefits of the proposed solution.

Environmental and industrial applications of pulsed power systems

International Nuclear Information System (INIS)

Neau, E.L.

1993-01-01

The technology base formed by the development of high peak power simulators, laser drivers, free electron lasers (FEL's), and Inertial Confinement Fusion (ICF) drivers from the early 60's through the late 80's is being extended to high average power short-pulse machines with the capabilities of performing new roles in environmental cleanup applications and in supporting new types of industrial manufacturing processes. Some of these processes will require very high average beam power levels of hundreds of kilowatts to perhaps megawatts. In this paper we briefly discuss new technology capabilities and then concentrate on specific application areas that may benefit from the high specific energies and high average powers attainable with short-pulse machines

Plating pulse switching power based on a CPLD

International Nuclear Information System (INIS)

Sun, Hongguo; Wu, Jun

2013-01-01

This paper presents a method of using a CPLD to generate a PWM trigger pulse to a full bridge inverter and a chopper circuit. This method results in a very good high power and low voltage large current pulse plating power supply. A single-chip microcomputer is the core of the feedback control system. A fuzzy PID algorithm with SCM and CPLD complexes precisely controls the output voltage, allowing it to maintain a constant value. The system contains a protection circuit that detects output current and output voltage and can correct the system if it enters an over-current abnormal state, ensuring that the driving circuit can effectively drive the IGBT. The circuit is also protected by setting the inverter frequency and dead time of a digital PWM chip. This method for bidirectional pulse plating power supply digital control was verified to be correct and practicable by a Matlab software simulation

Hollow-core fibers for high power pulse delivery

DEFF Research Database (Denmark)

Michieletto, Mattia; Lyngsø, Jens K.; Jakobsen, Christian

2016-01-01

We investigate hollow-core fibers for fiber delivery of high power ultrashort laser pulses. We use numerical techniques to design an anti-resonant hollow-core fiber having one layer of non-touching tubes to determine which structures offer the best optical properties for the delivery of high power...... picosecond pulses. A novel fiber with 7 tubes and a core of 30 mu m was fabricated and it is here described and characterized, showing remarkable low loss, low bend loss, and good mode quality. Its optical properties are compared to both a 10 mu m and a 18 mu m core diameter photonic band gap hollow......-core fiber. The three fibers are characterized experimentally for the delivery of 22 picosecond pulses at 1032nm. We demonstrate flexible, diffraction limited beam delivery with output average powers in excess of 70W. (C) 2016 Optical Society of America...

Generation of an XUV supercontinuum by optimization of the angle between polarization planes of two linearly polarized pulses in a multicycle two-color laser field

International Nuclear Information System (INIS)

Yao Jinping; Zeng Bin; Fu Yuxi; Chu Wei; Ni Jielei; Li Yao; Xiong Hui; Xu Han; Cheng Ya; Xu Zhizhan; Liu Xiaojun; Chen, J.

2010-01-01

We theoretically investigate the high-order harmonic generation (HHG) in helium using a two-color laser field synthesized by an intense 25-fs laser pulse at 800 nm and a relatively weak ∼43-fs laser pulse at 1400 nm. When the polarization between the two pulses is arranged at an angle of ∼73 deg., supercontinuum spectra are dramatically broadened to 180 eV, which is sufficient to support an isolated ∼73-as pulse without any phase compensation. The physical mechanisms behind the phenomenon are well explained in terms of quantum and classical analyses. Furthermore, in the long-pulse regime, this method of extending the supercontinuum spectrum shows the significant advantage over previous two-color HHG schemes.

Enhanced self-magnetic field by atomic polarization in partially stripped plasma produced by a short and intense laser pulse

International Nuclear Information System (INIS)

Hu Qianglin; Liu Shibing; Jiang, Y.J.; Zhang Jie

2005-01-01

The enhancement and redistribution of a self-generated quasistatic magnetic field, due to the presence of the polarization field induced by partially ionized atoms, are analytically revealed when a linearly polarized intense and short pulse laser propagates in a partially stripped plasma with higher density. In particular, the shorter wavelength of the laser pulse can evidently intensify the amplitude of the magnetic field. These enhancement and redistribution of the magnetic field are considered physically as a result of the competition of the electrostatic field (electron-ion separation) associated with the plasma wave, the atomic polarization field, and the pondoromotive potential associated with the laser field. This competition leads to the generation of a positive, large amplitude magnetic field in the zone of the pulse center, which forms a significant difference in partially and fully stripped plasmas. The numerical result shows further that the magnetic field is resonantly modulated by the plasma wave when the pulse length is the integer times the plasma wavelength. This apparently implies that the further enhancement and restructure of the large amplitude self-magnetic field can evidently impede the acceleration and stable transfer of the hot-electron beam

Pulsed Power Peer Review Committee Report

International Nuclear Information System (INIS)

Bloomquist, Douglas D.

2000-01-01

In 1993, the Government Performance and Results Act (GPRA, PL 103-62) was enacted. GPRA, which applies to all federal programs, has three components: strategic plans, annual performance plans, and metrics to show how well annual plans are being followed. As part of meeting the GRPA requirement in FY2000, a 14-member external peer review panel (the Garwin Committee) was convened on May 17-19, 2000 to review Sandia National Laboratories' Pulsed Power Programs as a component of the Performance Appraisal Process negotiated with the Department of Energy (DOE). The scope of the review included activities in inertial confinement fission (ICF), weapon physics, development of radiation sources for weapons effects simulation, x-ray radiography, basic research in high energy density physics (HEDP), and pulsed power technology research and development. In his charge to the committee, Jeffrey Quintenz, Director of Pulsed Power Sciences (1600) asked that the review be based on four criteria (1) quality of science, technology, and engineering, (2) programmatic performance, management, and planning, (3) relevance to national needs and agency missions, and (4) performance in the operation and construction of major research facilities. In addition, specific programmatic questions were posed by the director and by the DOE-Defense Programs (DP). The accompanying report, produced as a SAND document, is the report of the committee's findings

Pulsed power corona discharges for air pollution control

NARCIS (Netherlands)

Smulders, H.W.M.; Heesch, van E.J.M.; Paasen, van S.V.B.

1998-01-01

Successful introduction of pulsed corona for industrial purposes very much depends on the reliability of high-voltage and pulsed power technology and on the efficiency of energy transfer. In addition, it is of the utmost importance that adequate electromagnetic compatibility (EMC) is achieved

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

Science.gov (United States)

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.

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

Directory of Open Access Journals (Sweden)

Kohei Ueno

2017-02-01

Full Text Available 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 6μm. 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.

Development of fast pulsed power driver for radiography and Z-pinch

International Nuclear Information System (INIS)

Qiu Aici; Sun Fengju

2008-01-01

Z-pinch and flash X-ray radiography have an important application in inertial confine fusion (ICF) and nuclear radiation effects simulation and high performance hydrodynamic test, etc. Z-pinch ICF and multi-pulse multi-axis high energy X-ray radiography put forward a huge challenge for pulsed power driver, so the direct-driven-load fast pulsed power driver are developed actively in home and abroard. The paper summarized the recent advances and developing trends of the fast pulsed power driver based on fast Marx(FMG) and fast linear transformer driver (LTD), and analysized the advantages and disadvantages and restricting factors about FMG and FLTD and their key technologies, then introduced the state-of-arts on the investigation in Northwest Institute of Nuclear Technology. In the end, the paper presented some advices and views about studying fast pulsed power driver applied to Z-pinch and flash X-ray radiography in home. (authors)

Pulse power technology application to lasers

International Nuclear Information System (INIS)

Prestwich, K.R.

1975-01-01

Recent developments of intense relativistic electron beam accelerators and the associated pulse power technology are reviewed. The design of specific accelerators for gas laser excitation sources is discussed. A 3 MV, 800 kA, 24 ns electron beam accelerator under development for the electron beam fusion program is described along with the low jitter multichannel oil-dielectric rail switches developed for this application. This technology leads to the design of a 20 kJ, short pulse accelerator optimized gas laser excitation with radially converging electron beams. Other gas laser research requirements have led to the development of an accelerator that will produce a 0.5 MV, 20 kJ, 1 μs electron beam pulse. (auth)

Agricultural and Food Processing Applications of Pulsed Power and Plasma Technologies

Science.gov (United States)

Takaki, Koichi

Agricultural and food processing applications of pulsed power and plasma technologies are described in this paper. Repetitively operated compact pulsed power generators with a moderate peak power are developed for the agricultural and the food processing applications. These applications are mainly based on biological effects and can be categorized as germination control of plants such as Basidiomycota and arabidopsis inactivation of bacteria in soil and liquid medium of hydroponics; extraction of juice from fruits and vegetables; decontamination of air and liquid, etc. Types of pulsed power that have biological effects are caused with gas discharges, water discharges, and electromagnetic fields. The discharges yield free radicals, UV radiation, intense electric field, and shock waves. Biologically based applications of pulsed power and plasma are performed by selecting the type that gives the target objects the adequate result from among these agents or byproducts. For instance, intense electric fields form pores on the cell membrane, which is called electroporation, or influence the nuclei. This paper mainly describes the application of the pulsed power for the germination control of Basidiomycota i.e. mushroom, inactivation of fungi in the soil and the liquid medium in hydroponics, and extraction of polyphenol from skins of grape.

Influences of the pulsed power supply on corona streamer appearance

NARCIS (Netherlands)

Veldhuizen, van E.M.; Briels, T.M.P.; Grabowski, L.R.; Pemen, A.J.M.; Ebert, U.M.

2005-01-01

Pulsed positive corona streamers in air are studied by images obtained with an intensified CCD camera. Using a switched capacitor power supply, thin streamers are observed that branch. A power supply consisting of a 4-stage transmission line transformer gives pulses of much higher current to the

Physics and application of plasmas based on pulsed power technology

International Nuclear Information System (INIS)

Hotta, Eiki; Ozaki, Tetsuo

2012-04-01

The papers presented at the symposium on 'Physics and Application of Plasmas Based on Pulsed Power Technology' held on December 21-22, 2010 at National Institute of Fusion Science are collected. The papers in this proceeding reflect the current status and progress in the experimental and theoretical researches on high power particle beams and high energy density plasmas produced by pulsed power technology. (author)

Harmonic Dark Pulse Emission in Erbium-Doped Fiber Laser

International Nuclear Information System (INIS)

Zian, Cheak Tiu; Arman, Zarei; Sin, Jin Tan; Harith, Ahmad; Sulaiman, Wadi Harun

2015-01-01

A harmonic dark pulse generation in an erbium-doped fiber laser is demonstrated based on a figure-of-eight configuration. It is found that the harmonic dark pulse can be shifted from the fundamental to the 5"t"h order harmonic by increasing the pump power with an appropriate polarization controller orientation. The fundamental repetition rate of 20 kHz is obtained at the pump power of 29 mW. The highest pulse energy of 42.6 nJ is obtained at the fundamental repetition rate. The operating frequency of the dark pulse trains shifts to 2"n"d, 3"r"d, 4"t"h and 5"t"h harmonic as the pump powers are increased to 34 mW, 50 mW, 59 mW and 137 mW, respectively. (paper)

Pulse-power technology and its applications at LBT, Nagaoka

Energy Technology Data Exchange (ETDEWEB)

Yatsui, K; Masuda, W; Grigoriu, C; Masugata, K; Jiang, W; Imada, G; Imanari, K; Sonegawa, T; Chishiro, E [Laboratory of Beam Technology, Nagaoka University of Technology (Japan)

1997-12-31

Research activities on pulsed power technology and its applications at Laboratory of Beam Technology, Nagaoka University of Technology are reviewed. These activities include 1) development of a high power induction type linear accelerator (8 MV, 5 kA, 50 ns), 2) development of intense ion beam source, and 3) applications of pulsed ion beam in thin film and nanosize powder production. (author). 20 figs., 9 refs.

Pulsed power bibliography. Volume 2: Annotated bibliography

Science.gov (United States)

Bemesderfer, J.; Druce, R. L.; Frantz, B.; Guenther, A. H.; Kristiansen, M.; Oloughlin, J. P.; Pendleton, W. K.

1983-08-01

Pulsed power and high-voltage technologies are playing an ever increasing role in weapons' effects simulation, fusion power research, power distribution, materials processing and medical research. It is a rapidly expanding field of applied physics as evidenced by the growth in published literature. Three years ago, the Air Force Weapons Laboratory (AFWL) initiated a project to compile a computerized data base of pulsed power research papers. The data base is stored on our IBM System 2000. This AFWL Technical Report is the first release of the bibliography to date. It contains about 2,500 full bibliographic citations, original sources, availability, key words and abstracts. There are three indices: Subject, Personal Author, and Corporate. There are 30 main subject headings, from Breakdown Studies to Switching. Volume II contains the citations. In addition to these entries, the data base contains about 7,500 additional titles. As these titles are added to the full bibliography, they will be published.

High-power pre-chirp managed amplification of femtosecond pulses at high repetition rates

International Nuclear Information System (INIS)

Liu, Yang; Li, Wenxue; Zhao, Jian; Bai, Dongbi; Luo, Daping; Zeng, Heping

2015-01-01

Femtosecond pulses at 250 MHz repetition rate from a mode-locked fiber laser are amplified to high power in a pre-chirp managed amplifier. The experimental strategy offers a potential towards high-power ultrashort laser pulses at high repetition rates. By investigating the laser pulse evolution in the amplification processes, we show that self-similar evolution, finite gain bandwidth and mode instabilities determine pulse characteristics in different regimes. Further average power scaling is limited by the mode instabilities. Nevertheless, this laser system enables us to achieve sub-50 fs pulses with an average power of 93 W. (letter)

Power supply and pulsing strategies for the future linear colliders

International Nuclear Information System (INIS)

Brogna, A S; Weber, M; Göttlicher, P

2012-01-01

The concept of the power delivery systems of the future linear colliders exploits the pulsed bunch structure of the beam in order to minimize the average current in the cables and the electronics and thus to reduce the material budget and heat dissipation. Although modern integrated circuit technologies are already available to design a low-power system, the concepts on how to pulse the front-end electronics and further reduce the power are not yet well understood. We propose a possible implementation of a power pulsing system based on a DC/DC converter and we choose the Analog Hadron Calorimeter as a specific example. The model features large switching currents of electronic modules in short time intervals to stimulate the inductive components along the cables and interconnections.

A compact nanosecond pulse generator for DBD tube characterization

Science.gov (United States)

Rai, S. K.; Dhakar, A. K.; Pal, U. N.

2018-03-01

High voltage pulses of very short duration and fast rise time are required for generating uniform and diffuse plasma under various operating conditions. Dielectric Barrier Discharge (DBD) has been generated by high voltage pulses of short duration and fast rise time to produce diffuse plasma in the discharge gap. The high voltage pulse power generators have been chosen according to the requirement for the DBD applications. In this paper, a compact solid-state unipolar pulse generator has been constructed for characterization of DBD plasma. This pulsar is designed to provide repetitive pulses of 315 ns pulse width, pulse amplitude up to 5 kV, and frequency variation up to 10 kHz. The amplitude of the output pulse depends on the dc input voltage. The output frequency has been varied by changing the trigger pulse frequency. The pulsar is capable of generating pulses of positive or negative polarity by changing the polarity of pulse transformer's secondary. Uniform and stable homogeneous dielectric barrier discharge plasma has been produced successfully in a xenon DBD tube at 400-mbar pressure using the developed high voltage pulse generator.

Pulse Propagation in Presence of Polarization Mode Dispersion and Chromatic Dispersion in Single Mode Fibers

Directory of Open Access Journals (Sweden)

Hassan Abid Yasser

2013-01-01

Full Text Available The presence of (first and second orders polarization mode dispersion (PMD, chromatic dispersion, and initial chirp makes effects on the propagated pulses in single mode fiber. Nowadays, there is not an accurate mathematical formula that describes the pulse shape in the presence of these effects. In this work, a theoretical study is introduced to derive a generalized formula. This formula is exactly approached to mathematical relations used in their special cases. The presence of second-order PMD (SOPMD will not affect the orthogonality property between the principal states of polarization. The simulation results explain that the interaction of the SOPMD components with the conventional effects (chromatic dispersion and chirp will cause a broadening/narrowing and shape distortion. This changes depend on the specified values of SOPMD components as well as the present conventional parameters.

High-energy-density physics researches based on pulse power technology

International Nuclear Information System (INIS)

Horioka, Kazuhiko; Nakajima, Mitsuo; Kawamura, Tohru; Sasaki, Toru; Kondo, Kotaro; Yano, Yuuri

2006-01-01

Plasmas driven by pulse power device are of interest, concerning the researches on high-energy-density (HED) physics. Dense plasmas are produced using pulse power driven exploding discharges in water. Experimental results show that the wire plasma is tamped and stabilized by the surrounding water and it evolves through a strongly coupled plasma state. A shock-wave-heated, high temperature plasma is produced in a compact pulse power device. Experimental results show that strong shock waves can be produced in the device. In particular, at low initial pressure condition, the shock Mach number reaches 250 and this indicates that the shock heated region is dominated by radiation processes. (author)

Safety and shielding management for pulse power lab at IPR

International Nuclear Information System (INIS)

Upadhyay, Shweta; Faldu, Akash; Koshti, Rahul; Kumar, Rajesh

2016-01-01

Experiments in pulsed power lab works with very high voltage and high current regime for the nanosecond to microsecond time scale. This produces lot of electromagnetic noise, which can cause interference or malfunctioning of equipment. Laboratory Safety and protection are a very important aspect of science and engineering. Without it, practical performance could result in very serious injury, if not death. To reduce its effect electromagnetic shielding and grounding has to be enforced effectively. Pulse power lab deals with many safety issues like Radiation safety (shielding), High voltage safety, electrical and mechanical safety, etc. In this paper radiation all the safety aspects in pulse power lab is described. (author)

Space Solar Power Technology Demonstration for Lunar Polar Applications

Science.gov (United States)

Henley, M. W.; Fikes, J. C.; Howell, J.; Mankins, J. C.; Howell, J.

2002-01-01

A solar power generation station on a mountaintop near the moon's North or South pole can receive sunlight 708 hours per lunar day, for continuous power generation. Power can be beamed from this station over long distances using a laser-based wireless power transmission system and a photo-voltaic receiver. This beamed energy can provide warmth, electricity, and illumination for a robotic rover to perform scientific experiments in cold, dark craters where no other power source is practical. Radio-frequency power transmission may also be demonstrated in lunar polar applications to locate and recover sub-surface deposits of volatile material, such as water ice. High circular polarization ratios observed in data from Clementine spacecraft and Arecibo radar reflections from the moon's South pole suggest that water ice is indeed present in certain lunar polar craters. Data from the Lunar Prospector spacecraft's epi-thermal neutron spectrometer also indicate that hydrogen is present at the moon's poles. Space Solar Power technology enables investigation of these craters, which may contain a billion-year-old stratigraphic record of tremendous scientific value. Layers of ice, preserved at the moon's poles, could help us determine the sequence and composition of comet impacts on the moon. Such ice deposits may even include distinct strata deposited by secondary ejecta following significant Earth (ocean) impacts, linked to major extinctions of life on Earth. Ice resources at the moon's poles could provide water and air for human exploration and development of space as well as rocket propellant for future space transportation. Technologies demonstrated and matured via lunar polar applications can also be used in other NASA science missions (Valles Marineris. Phobos, Deimos, Mercury's poles, asteroids, etc.) and in future large-scale SSP systems to beam energy from space to Earth. Ground-based technology demonstrations are proceeding to mature the technology for such a near

Pulsed power supply system for neutron well logging

International Nuclear Information System (INIS)

Hopkinson, E.C.

1975-01-01

A variable D. C. power supply and a variable A. C. power supply are coupled onto the upper end of a single conductor cable at the earth's surface and from the lower end of said cable to a well logging instrument. The A. C. voltage is used to provide filament power for the ion source accelerator tube. The D. C. voltage is used to provide power to fixed D. C. loads maintained constant by regulators once a threshold is reached. The D. C. voltage is raised above the threshold to control the pulsed acceleration voltage and hence neutron output by first feeding into a unijunction relaxation oscillator in combination with an SCR output which output is transformer coupled into a voltage multiplier circuit. An antilatch feature is provided for the SCR by transformer coupling the pulses on the SCR anode back to the base of a transistor in series with the cathode of the SCR. Two outputs of the voltage multiplier circuit are connected to the cathode and anode, respectively, of an ion source accelerator tube, the cathode being connected through a resistor to retard the ripple pulsing of the cathode to allow ionization of the accelerator tube

Warm dense mater: another application for pulsed power hydrodynamics

Energy Technology Data Exchange (ETDEWEB)

Reinovsky, Robert Emil [Los Alamos National Laboratory

2009-01-01

Pulsed Power Hydrodynamics (PPH) is an application of low-impedance pulsed power, and high magnetic field technology to the study of advanced hydrodynamic problems, instabilities, turbulence, and material properties. PPH can potentially be applied to the study of the properties of warm dense matter (WDM) as well. Exploration of the properties of warm dense matter such as equation of state, viscosity, conductivity is an emerging area of study focused on the behavior of matter at density near solid density (from 10% of solid density to slightly above solid density) and modest temperatures ({approx}1-10 eV). Conditions characteristic of WDM are difficult to obtain, and even more difficult to diagnose. One approach to producing WDM uses laser or particle beam heating of very small quantities of matter on timescales short compared to the subsequent hydrodynamic expansion timescales (isochoric heating) and a vigorous community of researchers are applying these techniques. Pulsed power hydrodynamic techniques, such as large convergence liner compression of a large volume, modest density, low temperature plasma to densities approaching solid density or through multiple shock compression and heating of normal density material between a massive, high density, energetic liner and a high density central 'anvil' are possible ways to reach relevant conditions. Another avenue to WDM conditions is through the explosion and subsequent expansion of a conductor (wire) against a high pressure (density) gas background (isobaric expansion) techniques. However, both techniques demand substantial energy, proper power conditioning and delivery, and an understanding of the hydrodynamic and instability processes that limit each technique. In this paper we will examine the challenges to pulsed power technology and to pulsed power systems presented by the opportunity to explore this interesting region of parameter space.

Pulsed power bibliography. Volume 1. Indices. Final report

Energy Technology Data Exchange (ETDEWEB)

Bemesderfer, J.; Druce, R.L.; Frantz, B.; Guenther, A.H.; Kristiansen, M.

1983-08-01

Pulsed power and high-voltage technologies are playing an ever increasing role in weapons' effects simulation, fusion power research, power distribution, materials processing and medical research. It is a rapidly expanding field of applied physics as evidenced by the growth in published literature. Three years ago, the Air Force Weapons Laboratory (AFWL) initiated a project to compile a computerized data base of pulsed power research papers. The data base is stored on our IBM System 2000. This AFWL Technical Report is the first release of the bibliography to date. It contains about 2,500 full bibliographic citations, original sources, availability, key words and abstract. There are three indices: Subject, Personal Author, and Corporate Author. There are 30 main subject headings, from Breakdown Studies to Switching. The indices are contained in Volume I.

Transparent Si–DLC coatings on metals with high repetition bi-polar pulses of a PBII system

Energy Technology Data Exchange (ETDEWEB)

Ikeyama, Masami, E-mail: ikeyama3@aist.go.jp; Sonoda, Tsutomu, E-mail: tsutomu.sonoda@aist.go.jp

2013-07-15

Diamond-like carbon (DLC) is widely used because of its good properties. However, the color of DLC is usually dark brown or black. Recently, we have made fairly transparent Si contained DLC (Si–DLC) coatings in visible light region. The fairly transparent Si–DLC was made by using our original bi-polar pulse type plasma based ion implantation (PBII) system, with recently introduced high slew rate pulse power supply. The colors of metal sample surface were uniformly changed as subdued red, yellow, subdued green and subdued blue or violet, with the change of Si–DLC coating’s thickness. The colors come from the interference between reflected lights at the surface of the Si–DLC coatings and the surface of the metal samples. The colors were also changed with the angle of glancing. Estimated refractive indexes show well agreements among almost all Si–DLC coatings, instead of the differences of coating conditions. Generally, the longer coating time or slower coating process makes the higher refractive index in near infrared region. Estimated band gap of a Si–DLC coating was about 1.5 eV. The developed Si–DLC coatings must be useful as not only protective but also decorative coatings.

Pulsed Power Peer Review Committee Report

International Nuclear Information System (INIS)

BLOOMQUIST, DOUGLAS D.

2002-01-01

In 1993, the Government Performance and Results Act (GPRA, PL 103-62) was enacted. GPRA, which applies to all federal programs, has three components: strategic plans, annual performance plans, and metrics to show how well annual plans are being followed. As part of meeting the GRPA requirement in FY2002, a 15-member external review committee chaired by Dr. Alvin Trivelpiece (the Trivelpiece Committee) was convened by Sandia National Laboratories (SNL) on May 7-9, 2002 to review Sandia National Laboratories' Pulsed Power Programs as a component of the Performance Appraisal Process negotiated with the National Nuclear Security Administration of the Department of Energy (NNSA/DOE). The scope of the review included activities in high energy density physics (HEDP), inertial confinement fusion (ICF), radiation/weapon physics, the petawatt laser initiative (PW) and fast ignition, equation-of-state studies, radiation effects science and lethality, x-ray radiography, ZR development, basic research and pulsed power technology research and development, as well as electromagnetics and work for others. In his charge to the Committee, Dr. Jeffrey P. Quintenz, Director of Pulsed Power Sciences (Org. 1600) asked that the evaluation and feedback be based on three criteria: (1) quality of technical activities in science, technology, and engineering, (2) programmatic performance, management, and planning, and (3) relevance to national needs and agency missions. In addition, the director posed specific programmatic questions. The accompanying report, produced as a SAND document, is the report of the Committee's finding

Photoinduced electric currents in ring-shaped molecules by circularly polarized laser pulses

International Nuclear Information System (INIS)

Nobusada, Katsuyuki; Yabana, Kazuhiro

2007-01-01

We have theoretically demonstrated that circularly polarized laser pulses induce electric currents and magnetic moments in ring-shaped molecules Na 10 and benzene. The time-dependent adiabatic local density approximation is employed for this purpose, solving the time-dependent Kohn-Sham equation in real space and real time. It has been found that the electric currents are induced efficiently and persist continuously even after the laser pulses were switched off provided the frequency of the applied laser pulse is in tune with the excitation energy of the electronic excited state with the dipole strength for each molecular system. The electric currents are definitely revealed to be a second-order nonlinear optical response to the magnitude of the electric field. The magnetic dipole moments inevitably accompany the ring currents, so that the molecules are magnetized. The production of the electric currents and the magnetic moments in the present procedure is found to be much more efficient than that utilizing static magnetic fields

Development of highly repetitive pulse power system using amorphous metallic cores

Energy Technology Data Exchange (ETDEWEB)

Masugata, K; Yatsui, K [Nagaoka Univ. of Technology (Japan). Dept. of Electrical Engineering

1997-12-31

A new type of pulse power system has been developed to obtain an efficient highly repetitive pulse-power generation. The system is constructed of a double pulse circuit (1st stage), step-up transformer and Blumlein pulse forming line (BL) and can generate high power pulse of 600 kV, 24 kA, 60 ns. In the system, discharge gap switches are replaced by magnetic switches. In addition, instead of Marx generator, a step-up transformer is utilized to generate high voltage pulse. The system is tested under the double pulse mode where two 1st stage capacitors are connected in parallel and switched with a interval of T{sub d}. The minimum value of T{sub d} is limited by the recovery of 1st stage gap switches and at T{sub d} {>=} 500 {mu}s (equivalent rep-rate of 2 kHz), the system is operated with good reproducibility. To enhance the recovery, magnetic switch is utilized, which enables operation at T{sub d} {>=} 30 {mu}s (equivalent rep-rate of 33 kHz). (author). 7 figs., 7 refs.

Space Solar Power Technology Demonstration for Lunar Polar Applications: Laser-Photovoltaic Wireless Power Transmission

Science.gov (United States)

Henley, M. W.; Fikes, J. C.; Howell, J.; Mankins, J. C.; Howell, Joe T. (Technical Monitor)

2002-01-01

Space Solar Power technology offers unique benefits for near-term NASA space science missions, which can mature this technology for other future applications. "Laser-Photo-Voltaic Wireless Power Transmission" (Laser-PV WPT) is a technology that uses a laser to beam power to a photovoltaic receiver, which converts the laser's light into electricity. Future Laser-PV WPT systems may beam power from Earth to satellites or large Space Solar Power satellites may beam power to Earth, perhaps supplementing terrestrial solar photo-voltaic receivers. In a near-term scientific mission to the moon, Laser-PV WPT can enable robotic operations in permanently shadowed lunar polar craters, which may contain ice. Ground-based technology demonstrations are proceeding, to mature the technology for this initial application, in the moon's polar regions.

Pulsed Power for Solid-State Lasers

Energy Technology Data Exchange (ETDEWEB)

Gagnon, W; Albrecht, G; Trenholme, J; Newton, M

2007-04-19

Beginning in the early 1970s, a number of research and development efforts were undertaken at U.S. National Laboratories with a goal of developing high power lasers whose characteristics were suitable for investigating the feasibility of laser-driven fusion. A number of different laser systems were developed and tested at ever larger scale in pursuit of the optimum driver for laser fusion experiments. Each of these systems had associated with it a unique pulsed power option. A considerable amount of original and innovative engineering was carried out in support of these options. Ultimately, the Solid-state Laser approach was selected as the optimum driver for the application. Following this, the Laser Program at the Lawrence Livermore National Laboratory and the University of Rochester undertook aggressive efforts directed at developing the technology. In particular, at Lawrence Livermore National Laboratory, a series of laser systems beginning with the Cyclops laser and culminating in the present with the National Ignition Facility were developed and tested. As a result, a large amount of design information for solid-state laser pulsed power systems has been documented. Some of it is in the form of published papers, but most of it is buried in internal memoranda, engineering reports and LLNL annual reports. One of the goals of this book is to gather this information into a single useable format, such that it is easily accessed and understood by other engineers and physicists for use with future designs. It can also serve as a primer, which when seriously studied, makes the subsequent reading of original work and follow-up references considerably easier. While this book deals only with the solid-state laser pulsed power systems, in the bibliography we have included a representative cross section of papers and references from much of the very fine work carried out at other institutions in support of different laser approaches. Finally, in recent years, there has

The VELOCE pulsed power generator for isentropic compression experiments

Energy Technology Data Exchange (ETDEWEB)

Ao, Tommy [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Asay, James Russell [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Chantrenne, Sophie J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Hickman, Randall John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Willis, Michael David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Shay, Andrew W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Grine-Jones, Suzi A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Hall, Clint Allen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dynamic Material Properties; Baer, Melvin R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Engineering Sciences Center

2007-12-01

Veloce is a medium-voltage, high-current, compact pulsed power generator developed for isentropic and shock compression experiments. Because of its increased availability and ease of operation, Veloce is well suited for studying isentropic compression experiments (ICE) in much greater detail than previously allowed with larger pulsed power machines such as the Z accelerator. Since the compact pulsed power technology used for dynamic material experiments has not been previously used, it is necessary to examine several key issues to ensure that accurate results are obtained. In the present experiments, issues such as panel and sample preparation, uniformity of loading, and edge effects were extensively examined. In addition, magnetohydrodynamic (MHD) simulations using the ALEGRA code were performed to interpret the experimental results and to design improved sample/panel configurations. Examples of recent ICE studies on aluminum are presented.

Sub-100 fs pulses from an all-polarization maintaining Yb-fiber oscillator with an anomalous dispersion higher-order-mode fiber

DEFF Research Database (Denmark)

Verhoef, A.J.; Zhu, L.; Israelsen, Stine Møller

2015-01-01

, was investigated for different settings of the intracavity dispersion. When the cavity is operated with close to zero net dispersion, highly stable 0.5-nJ pulses externally compressed to sub-100-fs are generated. These are to our knowledge the shortest pulses generated from an all-polarization-maintaining Yb-fiber......We present an Yb-fiber oscillator with an all-polarization-maintaining cavity with a higher-order-mode fiber for dispersion compensation. The polarization maintaining higher order mode fiber introduces not only negative second order dispersion but also negative third order dispersion in the cavity......, in contrast to dispersion compensation schemes used in previous demonstrations of all-polarization maintaining Yb-fiber oscillators. The performance of the saturable absorber mirror modelocked oscillator, that employs a free space scheme for coupling onto the saturable absorber mirror and output coupling...

Multiwavelength Polarization of Rotation-powered Pulsars

Energy Technology Data Exchange (ETDEWEB)

Harding, Alice K.; Kalapotharakos, Constantinos [Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2017-05-10

Polarization measurements provide strong constraints on models for emission from rotation-powered pulsars. We present multiwavelength polarization predictions showing that measurements over a range of frequencies can be particularly important for constraining the emission location, radiation mechanisms, and system geometry. The results assume a generic model for emission from the outer magnetosphere and current sheet in which optical to hard X-ray emission is produced by synchrotron radiation (SR) from electron–positron pairs and γ -ray emission is produced by curvature radiation (CR) or SR from accelerating primary electrons. The magnetic field structure of a force-free magnetosphere is assumed and the phase-resolved and phase-averaged polarization is calculated in the frame of an inertial observer. We find that large position angle (PA) swings and deep depolarization dips occur during the light-curve peaks in all energy bands. For synchrotron emission, the polarization characteristics are strongly dependent on photon emission radius with larger, nearly 180°, PA swings for emission outside the light cylinder (LC) as the line of sight crosses the current sheet. The phase-averaged polarization degree for SR is less that 10% and around 20% for emission starting inside and outside the LC, respectively, while the polarization degree for CR is much larger, up to 40%–60%. Observing a sharp increase in polarization degree and a change in PA at the transition between X-ray and γ -ray spectral components would indicate that CR is the γ -ray emission mechanism.

Pulsed recording of anisotropy and holographic polarization gratings in azo-polymethacrylates with different molecular architectures

DEFF Research Database (Denmark)

Forcén, Patricia; Oriol, Luis; Alcala, Rafael

2008-01-01

Recording of anisotropy and holographic polarization gratings using 532 nm, 4 ns light pulses has been carried out in thin films of polymers with the same azobenzene content (20 wt %) and different molecular architectures. Random and block copolymers comprising azobenzene and methylmethacrylate (...

Innovation on high-power long-pulse gyrotrons

International Nuclear Information System (INIS)

Litvak, Alexander; Sakamoto, Keishi; Thumm, Manfred

2011-01-01

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 and 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.

Giessen polarization facility. III. Multi-detector analyzing system

Energy Technology Data Exchange (ETDEWEB)

Krause, H H; Stock, R; Arnold, W; Berg, H; Huttel, E; Ulbricht, J; Clausnitzer, G [Giessen Univ. (Germany, F.R.). Strahlenzentrum

1977-06-15

An analyzing system with a PDP 11 computer and a digital multiplexer is described. It allows to accept signals from 16 detectors with individual ADCs simultaneously. For measurements of analyzing powers the polarization of the ion beam can be switched to zero with a frequency of 1 kHz. The switching operation additionally controls the handling of the detector pulses. The software contains special programs for the analysis of polarization experiments.

High-Power Plasma Switch for 11.4 GHz Microwave Pulse Compressor

International Nuclear Information System (INIS)

Hirshfield, Jay L.

2010-01-01

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%.

Control strategy research of two stage topology for pulsed power supply

International Nuclear Information System (INIS)

Shi Chunfeng; Wang Rongkun; Huang Yuzhen; Chen Youxin; Yan Hongbin; Gao Daqing

2013-01-01

A kind of pulsed power supply of HIRFL-CSR was introduced, the ripple and the current error of the topological structure of the power in the operation process were analyzed, and two stage topology of pulsed power supply was given. The control strategy was simulated and the experiment was done in digital power platform. The results show that the main circuit structure and control method are feasible. (authors)

Progress in the pulsed power Inertial Confinement Fusion program

International Nuclear Information System (INIS)

Quintenz, J.P.; Matzen, M.K.; Mehlhorn, T.A.

1996-01-01

Pulsed power accelerators are being used in Inertial Confinement Fusion (ICF) research. In order to achieve our goal of a fusion yield in the range of 200 - 1000 MJ from radiation-driven fusion capsules, it is generally believed that ∼10 MJ of driver energy must be deposited within the ICF target in order to deposit ∼1 MJ of radiation energy in the fusion capsule. Pulsed power represents an efficient technology for producing both these energies and these radiation environments in the required short pulses (few tens of ns). Two possible approaches are being developed to utilize pulsed power accelerators in this effort: intense beams of light ions and z- pinches. This paper describes recent progress in both approaches. Over the past several years, experiments have successfully answered many questions critical to ion target design. Increasing the ion beam power and intensity are our next objectives. Last year, the Particle Beam Fusion Accelerator H (PBFA II) was modified to generate ion beams in a geometry that will be required for high yield applications. This 2048 modification has resulted in the production of the highest power ion beam to be accelerated from an extraction ion diode. We are also evaluating fast magnetically-driven implosions (z-pinches) as platforms for ICF ablator physics and EOS experiments. Z-pinch implosions driven by the 20 TW Saturn accelerator have efficiently produced high x- ray power (> 75 TW) and energy (> 400 kJ). Containing these x-ray sources within a hohlraum produces a unique large volume (> 6000 mm 3 ), long lived (>20 ns) radiation environment. In addition to studying fundamental ICF capsule physics, there are several concepts for driving ICF capsules with these x-ray sources. Progress in increasing the x-ray power on the Saturn accelerator and promise of further increases on the higher power PBFA II accelerator will be described

Self-channeling of high-power laser pulses through strong atmospheric turbulence

Science.gov (United States)

Peñano, J.; Palastro, J. P.; Hafizi, B.; Helle, M. H.; DiComo, G. P.

2017-07-01

We present an unusual example of truly long-range propagation of high-power laser pulses through strong atmospheric turbulence. A form of nonlinear self-channeling is achieved when the laser power is close to the self-focusing power of air and the transverse dimensions of the pulse are smaller than the coherence diameter of turbulence. In this mode, nonlinear self-focusing counteracts diffraction, and turbulence-induced spreading is greatly reduced. Furthermore, the laser intensity is below the ionization threshold so that multiphoton absorption and plasma defocusing are avoided. Simulations show that the pulse can propagate many Rayleigh lengths (several kilometers) while maintaining a high intensity. In the presence of aerosols, or other extinction mechanisms that deplete laser energy, the pulse can be chirped to maintain the channeling.

Monophasic Pulsed 200-μA Current Promotes Galvanotaxis With Polarization of Actin Filament and Integrin α2β1 in Human Dermal Fibroblasts.

Science.gov (United States)

Uemura, Mikiko; Maeshige, Noriaki; Koga, Yuka; Ishikawa-Aoyama, Michiko; Miyoshi, Makoto; Sugimoto, Masaharu; Terashi, Hiroto; Usami, Makoto

2016-01-01

The monophasic pulsed microcurrent is used to promote wound healing, and galvanotaxis regulation has been reported as one of the active mechanisms in the promotion of tissue repair with monophasic pulsed microcurrent. However, the optimum monophasic pulsed microcurrent parameters and intracellular changes caused by the monophasic pulsed microcurrent have not been elucidated in human dermal fibroblasts. The purpose of this study was to investigate the optimum intensity for promoting galvanotaxis and the effects of electrical stimulation on integrin α2β1 and actin filaments in human dermal fibroblasts. Human dermal fibroblasts were treated with the monophasic pulsed microcurrent of 0, 100, 200, or 300 μA for 8 hours, and cell migration and cell viability were measured 24 hours after starting monophasic pulsed microcurrent stimulation. Polarization of integrin α2β1 and lamellipodia formation were detected by immunofluorescent staining 10 minutes after starting monophasic pulsed microcurrent stimulation. The migration toward the cathode was significantly higher in the cells treated with the 200-μA monophasic pulsed microcurrent than in the controls (P microcurrent did not alter the migration ratio. The electrostimulus of 200 μA also promoted integrin α2β1 polarization and lamellipodia formation at the cathode edge (P microcurrent intensity to promote migration toward the cathode, and this intensity could regulate polarization of migration-related intracellular factors in human dermal fibroblasts.

Modeling particle emission and power flow in pulsed-power driven, nonuniform transmission lines

Directory of Open Access Journals (Sweden)

Nichelle Bruner

2008-04-01

Full Text Available Pulsed-power driven x-ray radiographic systems are being developed to operate at higher power in an effort to increase source brightness and penetration power. Essential to the design of these systems is a thorough understanding of electron power flow in the transmission line that couples the pulsed-power driver to the load. In this paper, analytic theory and fully relativistic particle-in-cell simulations are used to model power flow in several experimental transmission-line geometries fielded on Sandia National Laboratories’ upgraded Radiographic Integrated Test Stand [IEEE Trans. Plasma Sci. 28, 1653 (2000ITPSBD0093-381310.1109/27.901250]. Good agreement with measured electrical currents is demonstrated on a shot-by-shot basis for simulations which include detailed models accounting for space-charge-limited electron emission, surface heating, and stimulated particle emission. Resonant cavity modes related to the transmission-line impedance transitions are also shown to be excited by electron power flow. These modes can drive oscillations in the output power of the system, degrading radiographic resolution.

Pulsed power inductive energy storage in the microsecond range

International Nuclear Information System (INIS)

Rix, W.; Miller, A.R.; Thompson, J.; Waisman, E.; Wilkinson, M.; Wilson, A.

1993-01-01

During the past five years Maxwell has developed a series of inductive energy storage (IES) pulsed power generators; ACE 1, ACE 2, ACE 3, and ACE 4, to drive electron-beam loads. They are all based on a plasma opening switch (POS) contained in a single vacuum envelope operating at conduction times of around one microsecond. They all employ fast capacitor bank technology to match this conduction time without intermediate power conditioning. Oil or air filled transmission lines transfer capacitor bank energy to a vacuum section where the final pulse compression is accomplished. Development of the ACE series is described, emphasizing capacitor bank and the opening switch technology for delivering high voltage, multimegampere pulses to electron beam loads

Time-reversal asymmetry: polarization and analyzing power in nuclear reactions

International Nuclear Information System (INIS)

Rioux, C.; Roy, R.; Slobodrian, R.J.; Conzett, H.E.

1984-01-01

Measurements of the proton polarization in the reactions 7 Li( 3 He, p vector) 9 Be and 9 Be( 3 He, p vector) 11 B and of the analyzing powers in the inverse reactions, initiated by polarized protons at the same center-of-mass energies, show significant differences. This implies the failure of the polarization-analyzing-power theorem and, prima facie, of time-reversal invariance in these reactions. The reaction 2 H( 3 He, p vector) 4 He and its inverse have also been investigated and show smaller differences. A discussion of instrumental asymmetries is presented

Time asymmetry: Polarization and analyzing power in the nuclear reactions

International Nuclear Information System (INIS)

Rioux, C.; Roy, R.; Slobodrian, R.J.; Conzett, H.E.

1983-01-01

Measurements of the proton polarization in the reactions 7 Li( 3 He, p vector) 9 Be and 9 Be( 3 He, p vector) 11 B and of the analyzing powers of the inverse reactions, initiated by polarized protons at the same c.m. energies, show significant differences which imply the failure of the polarization-analyzing-power theorem and, prima facie, of time-reversal invariance in these reactions. The reaction 2 H( 3 He, p vector) 4 He and its inverse have also been investigated and show some smaller differences. A discussion of the instrumental asymmetries is presented. (orig.)

Pulsed power supplies for laser flashlamps. Final report

International Nuclear Information System (INIS)

Bird, W.L. Jr.; Driga, M.D.; Mayhall, D.J.T.; Brennan, M.

1978-10-01

A preliminary engineering design of a compensated pulse alternator for driving laser flashlamps is presented. The work performed by the Center for Electromechanics at The University of Texas at Austin also includes the optimization and revision of the prototype design for a compensated pulse alternator power supply for the NOVA laser system at Lawrence Livermore Laboratory

NO Detection by Pulsed Polarization of Lambda Probes–Influence of the Reference Atmosphere

Directory of Open Access Journals (Sweden)

Sabine Fischer

2013-11-01

Full Text Available The pulsed polarization measurement technique using conventional thimble type lambda probes is suitable for low ppm NOx detection in exhaust gas applications. To evaluate the underlying sensor mechanism, the unknown influence of the reference atmosphere on the NO sensing behavior is investigated in this study. Besides answering questions with respect to the underlying principle, this investigation can resolve the main question of whether a simplified sensor element without reference may be also suitable for NO sensing using the pulsed polarization measurement technique. With an adequate sensor setup, the reference atmosphere of the thimble type lambda probe is changed completely after a certain diffusion time. Thus, the sensor response regarding NO is compared with and without different gas atmospheres on both electrodes. It is shown that there is still a very good NO sensitivity even without reference air, although the NO response is reduced due to non-existing overlying mixed potential type voltage, which is otherwise caused by different atmospheres on both electrodes. Considering these results, we see an opportunity to simplify the standard NOx sensor design by omitting the reference electrode.

Pulsed Power Generators For Two-section Lia Relativistic Magnetron Driver

CERN Document Server

Agafonov, A V; Pevchev, V P

2004-01-01

Two prototypes of pulsed power generators for a two-sectional LIA - specialized driver of a relativistic magnetron were constructed and tested. The driver for the double-sided powering of a relativistic magnetron consists of two identical sets of induction modules (two sections of LIA) with inner electrodes - vacuum adders connected to both sides of a coaxial magnetron. It provides the symmetric power flowing in a magnetron and a possibility of localising of the electron flow in magnetron interaction region. The first generator designed for a small-scale laboratory installation provides the output pulses of 100 ns in duration with voltage amplitude of 50 kV at repetition rate of 1 pps. The construction of the generator is based on the application of experimental capacitor banks designed as a pulse forming line with the next parameters: charging voltage - 80 kV, impedance - 1,7 Ohm, pulse duration - 80 ns at a matched load. The second generator was designed for 1 MV integrated LIA - magnetron system. It cons...

Pulsed power safety and technical training at Sandia National Laboratories

International Nuclear Information System (INIS)

Goldstein, S.A.; Zawadzkas, G.A.; Donovan, G.L.; Mikkelson, K.A.; Sharpe, A.W.; Johnston, R.R.

1987-01-01

The expansion of pulsed power applications research at Sandia National Labs requires increasing technician-level support from individuals trained in high voltage, short pulse technology. Large superpower generators need a broad-based training curriculum in all aspects of accelerator operation to satisfy recent Department of Energy (DOE) desires for formal certification of accelerator operators. This paper discusses the status of Sandia's safety and technical training program in pulsed power technology directed mainly towards high school graduate and technical school level students. Present safety training methodology requires that hazards for experimental facilities are identified first, a specific curriculum is then tailored to individuals' background experiences and hazards involved with their current assignments. In the technical training program, certification requirements are being established and a coursework program has been initiated in which subjects are organized into two sections. The first covers electrical principles and physical properties of pulsed power components. The second presents various support-type subsystems for accelerators

Pulsed power drivers for ICF and high energy density physics

International Nuclear Information System (INIS)

Ramirez, J.J.; Matzen, M.K.; McDaniel, D.H.

1995-01-01

Nanosecond Pulsed Power Science and Technology has its origins in the 1960s and over the past decade has matured into a flexible and robust discipline capable of addressing key physics issues of importance to ICF and high Energy Density Physics. The major leverage provided by pulsed power is its ability to generate and deliver high energy and high power at low cost and high efficiency. A low-cost, high-efficiency driver is important because of the very large capital investment required for multi-megajoule ignition-class systems. High efficiency is of additional importance for a commercially viable inertial fusion energy option. Nanosecond pulsed power has been aggressively and successfully developed at Sandia over the past twenty years. This effort has led to the development of unique multi-purpose facilities supported by highly capable diagnostic, calculational and analytic capabilities. The Sandia Particle-beam Fusion Program has evolved as part of an integrated national ICF Program. It applies the low-cost, high-efficiency leverage provided by nanosecond pulsed power systems to the longer-term goals of the national program, i.e., the Laboratory Microfusion Facility and Inertial Fusion Energy. A separate effort has led to the application of nanosecond pulsed power to the generation of intense, high-energy laboratory x-ray sources for application to x-ray laser and radiation effects science research. Saturn is the most powerful of these sources to date. It generates ∼500 kilojoules of x-rays from a magnetically driven implosion (Z-pinch). This paper describes results of x-ray physics experiments performed on Saturn, plans for a new Z-pinch drive capability for PBFA-II, and a design concept for the proposed ∼15 MJ Jupiter facility. The opportunities for ICF-relevant research using these facilities will also be discussed

Pseudospark switches (PSS) for pulsed power applications

Energy Technology Data Exchange (ETDEWEB)

Heine, F; Prucker, U; Frank, K; Goertler, A; Schwandner, A; Tkotz, R; Hoffmann, D H.H.; Christiansen, J [Univ. of Erlangen (Germany). Physics Dept. I

1997-12-31

Based on the pseudospark discharge, a low pressure gas discharge in a special geometry, fast closing switches for different pulsed power applications have been designed. Medium power PSS ({<=} 30 kA peak current) were used in laser circuits whereas high current PSS are tested successfully in high current pulsed power applications ({<=} 200 kA). For currents of a few kA the discharge is supported by cathode spots on the cold cathode surface. For higher currents, anode activity is observed too. Inserting semiconductor material seems not only to suppress high erosive spot formation but to support diffuse large-area electrode emission. A different approach to solving the problem of lowering the erosion rate is the multichannel PSS (MUPS). In order to distribute the discharge current to more than one single channel, three or more discharge channels are radial or coaxial arranged. With regard to high voltage applications the maximum hold-off voltage was increased by adding an intermediate electrode. (author). 1 figs., 12 refs.

High Average Power, High Energy Short Pulse Fiber Laser System

Energy Technology Data Exchange (ETDEWEB)

Messerly, M J

2007-11-13

Recently continuous wave fiber laser systems with output powers in excess of 500W with good beam quality have been demonstrated [1]. High energy, ultrafast, chirped pulsed fiber laser systems have achieved record output energies of 1mJ [2]. However, these high-energy systems have not been scaled beyond a few watts of average output power. Fiber laser systems are attractive for many applications because they offer the promise of high efficiency, compact, robust systems that are turn key. Applications such as cutting, drilling and materials processing, front end systems for high energy pulsed lasers (such as petawatts) and laser based sources of high spatial coherence, high flux x-rays all require high energy short pulses and two of the three of these applications also require high average power. The challenge in creating a high energy chirped pulse fiber laser system is to find a way to scale the output energy while avoiding nonlinear effects and maintaining good beam quality in the amplifier fiber. To this end, our 3-year LDRD program sought to demonstrate a high energy, high average power fiber laser system. This work included exploring designs of large mode area optical fiber amplifiers for high energy systems as well as understanding the issues associated chirped pulse amplification in optical fiber amplifier systems.

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

Energy Technology Data Exchange (ETDEWEB)

Hirshfield, Jay L. [Omega-P, Inc., New Haven, CT (United States)

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.

PIC simulation of the vacuum power flow for a 5 terawatt, 5 MV, 1 MA pulsed power system

Science.gov (United States)

Liu, Laqun; Zou, Wenkang; Liu, Dagang; Guo, Fan; Wang, Huihui; Chen, Lin

2018-03-01

In this paper, a 5 Terawatt, 5 MV, 1 MA pulsed power system based on vacuum magnetic insulation is simulated by the particle-in-cell (PIC) simulation method. The system consists of 50 100-kV linear transformer drive (LTD) cavities in series, using magnetically insulated induction voltage adder (MIVA) technology for pulsed power addition and transmission. The pulsed power formation and the vacuum power flow are simulated when the system works in self-limited flow and load-limited flow. When the pulsed power system isn't connected to the load, the downstream magnetically insulated transmission line (MITL) works in the self-limited flow, the maximum of output current is 1.14 MA and the amplitude of voltage is 4.63 MV. The ratio of the electron current to the total current is 67.5%, when the output current reached the peak value. When the impedance of the load is 3.0 Ω, the downstream MITL works in the self-limited flow, the maximums of output current and the amplitude of voltage are 1.28 MA and 3.96 MV, and the ratio of the electron current to the total current is 11.7% when the output current reached the peak value. In addition, when the switches are triggered in synchronism with the passage of the pulse power flow, it effectively reduces the rise time of the pulse current.

High power microwave emission and diagnostics of microsecond electron beams

Energy Technology Data Exchange (ETDEWEB)

Gilgenbach, R; Hochman, J M; Jayness, R; Rintamaki, J I; Lau, Y Y; Luginsland, J; Lash, J S [Univ. of Michigan, Ann Arbor, MI (United States). Intense Electron Beam Interaction Lab.; Spencer, T A [Air Force Phillips Lab., Kirtland AFB, NM (United States)

1997-12-31

Experiments were performed to generate high power, long-pulse microwaves by the gyrotron mechanism in rectangular cross-section interaction cavities. Long-pulse electron beams are generated by MELBA (Michigan Electron Long Beam Accelerator), which operates with parameters: -0.8 MV, 1-10 kA, and 0.5-1 microsecond pulse length. Microwave power levels are in the megawatt range. Polarization control is being studied by adjustment of the solenoidal magnetic field. Initial results show polarization power ratios up to a factor of 15. Electron beam dynamics (V{sub perp}/V{sub par}) are being measured by radiation darkening on glass plates. Computer modeling utilizes the MAGIC Code for electromagnetic waves and a single electron orbit code that includes a distribution of angles. (author). 4 figs., 4 refs.

Power MOSFET Linearizer of a High-Voltage Power Amplifier for High-Frequency Pulse-Echo Instrumentation.

Science.gov (United States)

Choi, Hojong; Woo, Park Chul; Yeom, Jung-Yeol; Yoon, Changhan

2017-04-04

A power MOSFET linearizer is proposed for a high-voltage power amplifier (HVPA) used in high-frequency pulse-echo instrumentation. The power MOSFET linearizer is composed of a DC bias-controlled series power MOSFET shunt with parallel inductors and capacitors. The proposed scheme is designed to improve the gain deviation characteristics of the HVPA at higher input powers. By controlling the MOSFET bias voltage in the linearizer, the gain reduction into the HVPA was compensated, thereby reducing the echo harmonic distortion components generated by the ultrasonic transducers. In order to verify the performance improvement of the HVPA implementing the power MOSFET linearizer, we measured and found that the gain deviation of the power MOSFET linearizer integrated with HVPA under 10 V DC bias voltage was reduced (-1.8 and -0.96 dB, respectively) compared to that of the HVPA without the power MOSFET linearizer (-2.95 and -3.0 dB, respectively) when 70 and 80 MHz, three-cycle, and 26 dB m input pulse waveforms are applied, respectively. The input 1-dB compression point (an index of linearity) of the HVPA with power MOSFET linearizer (24.17 and 26.19 dB m at 70 and 80 MHz, respectively) at 10 V DC bias voltage was increased compared to that of HVPA without the power MOSFET linearizer (22.03 and 22.13 dB m at 70 and 80 MHz, respectively). To further verify the reduction of the echo harmonic distortion components generated by the ultrasonic transducers, the pulse-echo responses in the pulse-echo instrumentation were compared when using HVPA with and without the power MOSFET linearizer. When three-cycle 26 dB m input power was applied, the second, third, fourth, and fifth harmonic distortion components of a 75 MHz transducer driven by the HVPA with power MOSFET linearizer (-48.34, -44.21, -48.34, and -46.56 dB, respectively) were lower than that of the HVPA without the power MOSFET linearizer (-45.61, -41.57, -45.01, and -45.51 dB, respectively). When five-cycle 20 dB m input

Capillary Ion Concentration Polarization for Power-Free Salt Purification

Science.gov (United States)

Park, Sungmin; Jung, Yeonsu; Cho, Inhee; Kim, Ho-Young; Kim, Sung Jae

2014-11-01

In this presentation, we experimentally and theoretically demonstrated the capillary based ion concentration polarization for power-free salt purification system. Traditional ion concentration polarization phenomenon has been studied for a decade for both fundamental nanoscale fluid dynamics and novel engineering applications such as desalination, preconcentration and energy harvesting devices. While the conventional system utilizes an external power source, the system based on capillary ion concentration polarization is capable of perm-selective ion transportation only by capillarity so that the same ion depletion zone can be formed without any external power sources. An ion concentration profile near the nanostructure was tracked using fluorescent probes and analyzed by solving the modified Nernst-Planck equation. As a result, the concentration in the vicinity of the nanostructure was at least 10 times lower than that of bulk electrolyte and thus, the liquid absorbed into the nanostructure had the low concentration. This mechanism can be used for the power free salt purification system which would be significantly useful in underdeveloped and remote area. This work was supported by Samsung Research Funding Center of Samsung Electronics under Project Number SRFC-MA1301-02.

Time asymmetry: Polarization and analyzing power in the nuclear reactions

Energy Technology Data Exchange (ETDEWEB)

Rioux, C.; Roy, R.; Slobodrian, R.J. (Laval Univ., Quebec City (Canada). Lab. de Physique Nucleaire); Conzett, H.E. (California Univ., Berkeley (USA). Lawrence Berkeley Lab.)

1983-02-28

Measurements of the proton polarization in the reactions /sup 7/Li(/sup 3/He, p vector)/sup 9/Be and /sup 9/Be(/sup 3/He, p vector)/sup 11/B and of the analyzing powers of the inverse reactions, initiated by polarized protons at the same c.m. energies, show significant differences which imply the failure of the polarization-analyzing-power theorem and, prima facie, of time-reversal invariance in these reactions. The reaction /sup 2/H(/sup 3/He, p vector)/sup 4/ He and its inverse have also been investigated and show some smaller differences. A discussion of the instrumental asymmetries is presented.

A study of the transient plasma potential in a pulsed bi-polar dc magnetron discharge

International Nuclear Information System (INIS)

Bradley, J W; Karkari, S K; Vetushka, A

2004-01-01

The temporal evolution of the plasma potential, V p , in a pulsed dc magnetron plasma has been determined using the emissive probe technique. The discharge was operated in the 'asymmetric bi-polar' mode, in which the discharge voltage changes polarity during part of the pulse cycle. The probe measurements, with a time-resolution of 20 ns or better, were made along a line above the racetrack, normal to the plane of the cathode target, for a fixed frequency (100 kHz), duty cycle (50%), argon pressure (0.74 Pa) and discharge power (583 W). At all the measured positions, V p was found to respond to the large and rapid changes in the cathode voltage, V d , during the different phases of the pulse cycle, with V p always more positive than V d . At a typical substrate position (>80 mm from the target), V p remains a few volts above the most positive surface in the discharge at all times. In the 'on' phase of the pulse, the measurements show a significant axial electric field is generated in the plasma, with the plasma potential dropping by a total of about 30 V over a distance of 70 mm, from the bulk plasma to a position close to the beginning of the cathode fall. This is consistent with measurements made in the dc magnetron. During the stable 'reverse' phase of the discharge, for distances greater than 18 mm from the target, the axial electric field is found to collapse, with V p elevated uniformly to about 3 V above V d . Between the target and this field-free region an ion sheath forms, and the current flowing to the target is still an ion current in this 'reverse' period. During the initial 200 ns of the voltage 'overshoot' phase (between 'on' and 'reverse' phases), V d reached a potential of +290 V; however, close to the target, V p was found to attain a much higher value, namely +378 V. Along the line of measurement, the axial electric field reverses in direction in this phase, and an electron current of up to 9 A flows to the target. The spatial and temporal

Fault analysis and strategy of high pulsed power supply for high power laser

International Nuclear Information System (INIS)

Liu Kefu; Qin Shihong; Li Jin; Pan Yuan; Yao Zonggan; Zheng Wanguo; Guo Liangfu; Zhou Peizhang; Li Yizheng; Chen Dehuai

2001-01-01

according to the requirements of driving flash-lamp, a high pulsed power supply (PPS) based on capacitors as energy storage elements is designed. The author analyzes in detail the faults of high pulsed power supply for high power laser. Such as capacitor internal short-circuit, main bus breakdown to ground, flashlamp sudden short or break. The fault current and voltage waveforms were given by circuit simulations. Based on the analysis and computation, the protection strategy with the fast fuse and ZnO was put forward, which can reduce the damage of PPS to the lower extent and provide the personnel safe and collateral property from the all threats. The preliminary experiments demonstrated that the design of the PPS can satisfy the project requirements

A pulse amplitude discriminator with very low-power consuming

International Nuclear Information System (INIS)

Deng Changming; Liu Zhengshan; Zhang Zhiyong; Cheng Chang

2000-01-01

A low-power pulse amplitude discriminator is described. The discriminator circuit is mainly composed of an integrated voltage comparator, MAX921, and owns the characters of very low-power and low operating voltage

SBS pulse compression for excimer inertial fusion energy drivers

International Nuclear Information System (INIS)

Linford, G.J.

1994-01-01

A key requirement for the development of commercial fusion power plants utilizing inertial confinement fusion (ICF) as a source of thermonuclear power is the availability of reliable, efficient laser drivers. These laser drivers must be capable of delivering UV optical pulses having energies of the order of 5MJ to cryogenic deuterium-tritium (D/T) ICF targets. The current requirements for laser ICF target irradiation specify the laser wavelength, λ ca. 250 nm, pulse duration, τ p ca. 6 ns, bandwidth, Δλ ca. 0.1 nm, polarization state, etc. Excimer lasers are a leading candidate to fill these demanding ICF driver requirements. However, since excimer lasers are not storage lasers, the excimer laser pulse duration, τ pp , is determined primarily by the length of the excitation pulse delivered to the excimer laser amplifier. Pulsed power associated with efficiently generating excimer laser pulses has a time constant, τ pp which falls in the range, 30 τ p pp p . As a consequence, pulse compression is needed to convert the long excimer laser pulses to pulses of duration τ p . These main ICF driver pulses require, in addition, longer, lower power precursor pulses delivered to the ICF target before the arrival of the main pulse. Although both linear and non-linear optical (NLO) pulse compression techniques have been developed, computer simulations have shown that a ''chirped,'' self-seeded, stimulated Brillouin scattering (SBS) pulse compressor cell using SF 6 at a density, ρ ca. 1 amagat can efficiently compress krypton fluoride (KrF) laser pulses at λ=248 nm. In order to avoid the generation of output pulses substantially shorter than τ p , the optical power in the chirped input SBS ''seed'' beams was ramped. Compressed pulse conversion efficiencies of up to 68% were calculated for output pulse durations of τ p ca. ns

Physics and applications of plasmas produced by pulsed power technology

International Nuclear Information System (INIS)

Ozaki, Tetsuo; Katsuki, Sunao

2013-10-01

The papers presented at the symposium on 'Physics and Applications of Plasmas Produced by Pulsed Power Technology' held on March 27-28, 2012 at the National Institute for Fusion Science are collected in these proceedings. The papers in these proceedings reflect the current status and progress in the experimental and theoretical research on high power particle beams and high energy density plasmas produced by pulsed power technology. This issue is the collection of 22 papers presented at the entitled meeting. Ten of the presented papers are indexed individually. (J.P.N.)

Repetitive plasma opening switch for powerful high-voltage pulse generators

International Nuclear Information System (INIS)

Dolgachev, G.I.; Zakatov, L.P.; Nitishinskii, M.S.; Ushakov, A.G.

1998-01-01

Results are presented of experimental studies of plasma opening switches that serve to sharpen the pulses of inductive microsecond high-voltage pulse generators. It is demonstrated that repetitive plasma opening switches can be used to create super-powerful generators operating in a quasi-continuous regime. An erosion switching mechanism and the problem of magnetic insulation in repetitive switches are considered. Achieving super-high peak power in plasma switches makes it possible to develop new types of high-power generators of electron beams and X radiation. Possible implementations and the efficiency of these generators are discussed

Single attosecond pulse generation in an orthogonally polarized two-color laser field combined with a static electric field

International Nuclear Information System (INIS)

Xia Changlong; Zhang Gangtai; Wu Jie; Liu Xueshen

2010-01-01

We investigate theoretic high-order harmonic generation and single attosecond pulse generation in an orthogonally polarized two-color laser field, which is synthesized by a mid-infrared (IR) pulse (12.5 fs, 2000 nm) in the y component and a much weaker (12 fs, 800 nm) pulse in the x component. We find that the width of the harmonic plateau can be extended when a static electric field is added in the y component. We also investigate emission time of harmonics in terms of a time-frequency analysis to illustrate the physical mechanism of high-order harmonic generation. We calculate the ionization rate using the Ammosov-Delone-Krainov model and interpret the variation of harmonic intensity for different static electric field strengths. When the ratio of strengths of the static and the y-component laser fields is 0.1, a continuous harmonic spectrum is formed from 220 to 420 eV. By superposing a properly selected range of the harmonic spectrum from 300 to 350 eV, an isolated attosecond pulse with a duration of about 75 as is obtained, which is near linearly polarized.

Layout of NALM fiber laser with adjustable peak power of generated pulses.

Science.gov (United States)

Smirnov, Sergey; Kobtsev, Sergey; Ivanenko, Alexey; Kokhanovskiy, Alexey; Kemmer, Anna; Gervaziev, Mikhail

2017-05-01

The Letter proposes a new layout of a passively mode-locked fiber laser based on a nonlinear amplifying loop mirror (NALM) with two stretches of active fiber and two independently controlled pump modules. In contrast with conventional NALM configurations using a single piece of active fiber that yields virtually constant peak power, the proposed novel laser features larger than a factor of 2 adjustment range of peak power of generated pulses. The proposed layout also provides independent adjustment of duration and peak power of generated pulses as well as power-independent control of generated pulse spectral width impossible in NALM lasers with a single piece of active fiber.

Ultra-long-pulse microwave negative high voltage power supply with fast protection

International Nuclear Information System (INIS)

Xu Weihua; Wu Junshuan; Zheng Guanghua; Huang Qiaolin; Yang Chunsheng; Zhou Yuanwei; Chen Yonghao

1998-01-01

Two 1.4 MW high voltage power supply (HVPS) modules with 3-5 s pulse duration have been developed for LHCD experiment in the HT-7 tokamak. The power source consists of a pulsed generator and the electric circuit. Duration of the ultra-long-pulse is controlled by switching-on dc relay immediately and switching-off ac contactor after a given time, and the fast protection is executed by a crowbar. Due to the soft starting of the power source, the problem of overvoltage induced by dc relay switching-on has been solved. Each power supply module outputs a rated power (-35 kV, 40 A) on the dummy load. With the klystrons connected as the load of the power supply modules, LHCD experiments have been conducted successfully in the HT-7 tokamak

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

Science.gov (United States)

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

Pulsed power for angular multiplexed laser fusion drivers

International Nuclear Information System (INIS)

Eninger, J.E.

1983-01-01

The feasibility of using rare gas-halide lasers, in particular the KrF laser, as inertial confinement fusion (ICF) drivers has been assessed. These lasers are scalable to the required high energy (approx. =1-5 MJ) in a short pulse (approx. =10 ns) by optical angular multiplexing, and integration of the output from approx. =100 kJ laser amplifier subsystems. The e-beam current density (approx. =50A/cm 2 ) and voltage (approx. =800 kV) required for these power amplifiers lead to an e-beam impedance of approx. =0.2Ω for approx. =300 ns pump time. This impedance level requires modularization of the large area e-gun, a) to achieve a diode inductance consistent with fast current risetime, b) to circumvent dielectric breakdown constraints in the pulse forming lines, and c) to reduce the requirement for guide magnetic fields. Pulsed power systems requirements, design concepts, scalability, tradeoffs, and performance projections are discussed in this paper

Proceedings of the Japan-US workshop on plasma polarization spectroscopy and the international seminar on plasma polarization spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Fujimoto, Takashi; Beiersdorfer, Peter [eds.

1998-06-01

The international meeting on Plasma Polarization Spectroscopy (PPS) was held in Kyoto during January 26-28, 1998. This Proceedings book includes the papers of the talks given at the meeting. These include: overviews of PPS from the aspects of atomic physics, and of plasma physics; several PPS and MSE (motional Stark effect) experiments on magnetically confined plasmas and a laser-produced plasma; polarized laser-induced fluorescence spectroscopy, several experiments on EBITs (electron beam ion trap) and their theoretical interpretations; polarized profiles of spectral lines, basic formulation of PPS; inelastic and elastic electron collisions leading to polarized atomic states; polarization in recombining plasma; relationship between the collisional polarization relaxation and the line broadening; and characteristics of the plasma produced by very short pulse and high power laser irradiation. The 19 of the presented papers are indexed individually. (J.P.N.)

Helicity-Selective Phase-Matching and Quasi-Phase matching of Circularly Polarized High-Order Harmonics: Towards Chiral Attosecond Pulses

Science.gov (United States)

2016-05-23

2 Department of Physics and JILA, University of Colorado and NIST, Boulder, CO 80309, USA 3Department of Physics and Optical Engineering, Ort Braude...polarized high harmonic generation, phase matching, ultrafast chiral physics, attosecond pulses (Some figures may appear in colour only in the online...temporal resolution and in spectral regions unavailable to circular polarization thus far. Acknowledgments This work was supported by the USA –Israel

Pulse power applications of flux compression generators

International Nuclear Information System (INIS)

Fowler, C.M.; Caird, R.S.; Erickson, D.J.; Freeman, B.L.

1981-01-01

Characteristics are presented for two different types of explosive driven flux compression generators and a megavolt pulse transformer. Status reports are given for rail gun and plasma focus programs for which the generators serve as power sources

Research on laser detonation pulse circuit with low-power based on super capacitor

Science.gov (United States)

Wang, Hao-yu; Hong, Jin; He, Aifeng; Jing, Bo; Cao, Chun-qiang; Ma, Yue; Chu, En-yi; Hu, Ya-dong

2018-03-01

According to the demand of laser initiating device miniaturization and low power consumption of weapon system, research on the low power pulse laser detonation circuit with super capacitor. Established a dynamic model of laser output based on super capacitance storage capacity, discharge voltage and programmable output pulse width. The output performance of the super capacitor under different energy storage capacity and discharge voltage is obtained by simulation. The experimental test system was set up, and the laser diode of low power pulsed laser detonation circuit was tested and the laser output waveform of laser diode in different energy storage capacity and discharge voltage was collected. Experiments show that low power pulse laser detonation based on super capacitor energy storage circuit discharge with high efficiency, good transient performance, for a low power consumption requirement, for laser detonation system and low power consumption and provide reference light miniaturization of engineering practice.

An innovative high-power constant-current pulsed-arc power-supply for a high-density pulsed-arc-plasma ion-source using a LaB6-filament.

Science.gov (United States)

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.

An innovative high-power constant-current pulsed-arc power-supply for a high-density pulsed-arc-plasma ion-source using a LaB6-filament

International Nuclear Information System (INIS)

Ueno, A.; Oguri, H.; Ikegami, K.; Namekawa, Y.; Ohkoshi, K.; Tokuchi, A.

2010-01-01

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 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 Ax140 V) and a duty factor of more than 1.5%(600 μsx25 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.

High power all solid state VUV lasers

International Nuclear Information System (INIS)

Zhang, Shen-jin; Cui, Da-fu; Zhang, Feng-feng; Xu, Zhi; Wang, Zhi-min; Yang, Feng; Zong, Nan; Tu, Wei; Chen, Ying; Xu, Hong-yan; Xu, Feng-liang; Peng, Qin-jun; Wang, Xiao-yang; Chen, Chuang-tian; Xu, Zu-yan

2014-01-01

Highlights: • Polarization and pulse repetition rate adjustable ps 177.3 nm laser was developed. • Wavelength tunable ns, ps and fs VUV lasers were developed. • High power ns 177.3 nm laser with narrow linewidth was investigated. - Abstract: We report the investigation on the high power all solid state vacuum ultra-violet (VUV) lasers by means of nonlinear frequency conversion with KBe 2 BO 3 F 2 (KBBF) nonlinear crystal. Several all solid state VUV lasers have developed in our group, including polarization and pulse repetition rate adjustable picosecond 177.3 nm VUV laser, wavelength tunable nanosecond, picosecond and femtosecond VUV lasers, high power ns 177.3 nm laser with narrow linewidth. The VUV lasers have impact, accurate and precise advantage

Pulsed power ion accelerators for inertially confined fusion

International Nuclear Information System (INIS)

Olson, C.L.

1976-01-01

Current research is described on pulsed power ion accelerators for inertial fusion, i.e., ion diodes and collective accelerators. Particle beam energy and power requirements for fusion, and basic deposition characteristics of charged particle beams are discussed. Ion diodes and collective accelerators for fusion are compared with existing conventional accelerators

The powerful pulsed electron beam effect on the metallic surfaces

International Nuclear Information System (INIS)

Neklyudov, I.M.; Yuferov, V.B.; Kosik, N.A.; Druj, O.S.; Skibenko, E.I.

2001-01-01

Experimental results of the influence of powerful pulsed electron beams on the surface structure,hardness and corrosion resistance of the Cr18ni10ti steel are presented. The experiments were carried out in the powerful electron accelerators of directional effect VGIK-1 and DIN-2K with an energy up to approx 300 KeV and a power density of 10 9 - 10 11 W/cm 2 for micro- and nanosecond range. The essential influence of the irradiation power density on the material structure was established. Pulsed powerful beam action on metallic surface leads to surface melting,modification of the structure and structure-dependent material properties. The gas emission and mass-spectrometer analysis of the beam-surface interaction were defined

Magnetic insulation, power flow, and pulse power results on RITS-3

International Nuclear Information System (INIS)

Johnson, David L.; Smith, Ian; Corcoran, Patrick; Bailey, Vernon; Maenchen, John; Rovang, Dean; Molina, Isidro; Hahn, Kelly; Lucero, Robert; Kincy, Mark; Kitterman, David; Oliver, Bryan; Welch, Dale; Rose, David; Goldsack, Timothy J.; Phillips, Martin A.; Sinclair, Mark A.; Thomas, Kenneth J.

2002-01-01

RITS (Radiographic Integrated Test Stand) is an induction voltage adder designed by Sandia and PSD to provide 16-MV, 150-kA electron beams and other capabilities. Previous publications have reported on tests of a single pulse forming line and adder cell, including initial results of the effects of various degrees of non-uniform injection of current into the adder bore on magnetic insulation and power flow in the downstream MITL. Now RITS-3 has been constructed, consisting of three pfls driven by a common intermediate store; three induction cells, one driven by each pfl; a three-stage, 4-MV, 150-kA vacuum voltage adder; and an output MITL and diode. Here we report on (1) simulations of the three-stage adder using the MRC 3-D particle-in-cell code LSP that address the effects of injected current non-uniformities on magnetic insulation and power-flow both upstream and downstream in a multi-cell adder; (2) experimental results compared with simulations; and (3) initial performance of the RITS-3 pulse power

Pulsed power sources based on MHD generators (A state-of-art review)

International Nuclear Information System (INIS)

Das, A.K.; Venkatramani, N.; Rohatgi, V.K.

1986-01-01

pulsed Power sources are finding increased applications in powering plasma experiments, CTF devices, investigations of structure of earth's crust or self-contained compact power supplies for military applications. This report reviews the development of magnetohydrodynamic (MHD) power systems for pulsed power applications. The major critical components, which are analysed in detail, include the combustor, high energy fuel development, high field magnet, high power density channel and power conditioning unit. The report concludes that the MHD research has now reached a stage, where it is possible to design and achieve requisite performance from short duration high power compact MHD generators. (author)

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

Science.gov (United States)

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.

Conducted noise analysis and protection of 45 kJ/s, ±50 kV capacitor charging power supply when interfaced with repetitive Marx based pulse power system

Science.gov (United States)

Naresh, P.; Patel, Ankur; Sharma, Archana

2015-09-01

Pulse power systems with highly dynamic loads like klystron, backward wave oscillator (BWO), and magnetron generate highly dynamic noise. This noise leads to frequent failure of controlled switches in the inverter stage of charging power supply. Designing a reliable and compatible power supply for pulse power applications is always a tricky job when charging rate is in multiples of 10 kJ/s. A ±50 kV and 45 kJ/s capacitor charging power supply based on 4th order LCLC resonant topology has been developed for a 10 Hz repetitive Marx based system. Conditions for load independent constant current and zero current switching (ZCS) are derived mathematically. Noise generated at load end due to dynamic load is tackled effectively and reduction in magnitude noise voltage is achieved by providing shielding between primary and secondary of high voltage high frequency transformer and with LCLC low pass filter. Shielding scales down the ratio between coupling capacitance (Cc) and the collector-emitter capacitance of insulated gate bi-polar transistor switch, which in turn reduces the common mode noise voltage magnitude. The proposed 4th order LCLC resonant network acts as a low pass filter for differential mode noise in the reverse direction (from load to source). Power supply has been tested repeatedly with 5 Hz repetition rate with repetitive Marx based system connected with BWO load working fine without failure of single switch in the inverter stage.

Polar lunar power ring: Propulsion energy resource

Science.gov (United States)

Galloway, Graham Scott

1990-01-01

A ring shaped grid of photovoltaic solar collectors encircling a lunar pole at 80 to 85 degrees latitude is proposed as the primary research, development, and construction goal for an initial lunar base. The polar Lunar Power Ring (LPR) is designed to provide continuous electrical power in ever increasing amounts as collectors are added to the ring grid. The LPR can provide electricity for any purpose indefinitely, barring a meteor strike. The associated rail infrastructure and inherently expandable power levels place the LPR as an ideal tool to power an innovative propulsion research facility or a trans-Jovian fleet. The proposed initial output range is 90 Mw to 90 Gw.

Sub-100 fs pulses from an all-polarization maintaining Yb-fiber oscillator with an anomalous dispersion higher-order-mode fiber

DEFF Research Database (Denmark)

Verhoef, A. J.; Zhu, L.; Israelsen, Stine Møller

2015-01-01

, was investigated for different settings of the intracavity dispersion. When the cavity is operated with close to zero net dispersion, highly stable 0.5-nJ pulses externally compressed to sub-100-fs are generated. These are to our knowledge the shortest pulses generated from an all-polarization-maintaining Yb-fiber......We present an Yb-fiber oscillator with an all-polarizationmaintaining cavity with a higher-order-mode fiber for dispersion compensation. The polarization maintaining higher order mode fiber introduces not only negative second order dispersion but also negative third order dispersion in the cavity......, in contrast to dispersion compensation schemes used in previous demonstrations of all-polarization maintaining Yb-fiber oscillators. The performance of the saturable absorber mirror modelocked oscillator, that employs a free space scheme for coupling onto the saturable absorber mirror and output coupling...

Simulation of subnanosecond streamers in atmospheric-pressure air: Effects of polarity of applied voltage pulse

Energy Technology Data Exchange (ETDEWEB)

Babaeva, N. Yu.; Naidis, G. V. [Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412 (Russian Federation)

2016-08-15

Results of simulation of subnanosecond streamer propagation in corona gap configuration, obtained in the framework of 2D fluid model, are presented. Effects related with the polarity of a voltage pulse applied to the stressed electrode are discussed. It is argued that these effects (dependence of the discharge current and propagation velocity on the polarity of applied voltage) observed in experiments can be attributed to the difference in initial (preceding the streamer formation) distributions of charged species inside the gap. This difference can be caused by preionization (at negative polarity) of the gas inside the discharge gap by runaway electrons. Calculated streamers have large widths (up to 1 cm) and move with velocities in the range of 10{sup 9}–10{sup 10 }cm s{sup −1}, similar to experimental data.

Wavelength stabilized high pulse power laser diodes for automotive LiDAR

Science.gov (United States)

Knigge, A.; Klehr, A.; Wenzel, H.; Zeghuzi, A.; Fricke, J.; Maaßdorf, A.; Liero, A.; Tränkle, G.

2018-03-01

Diode lasers generating optical pulses with high peak power and lengths in the nanosecond range are key components of systems for free-space communication, metrology, material processing, spectroscopy, and light detection and ranging (LiDAR) as needed for object detection and autonomous driving. Automotive LiDAR systems demand additionally a good beam quality and low wavelength shift with temperature due to the wide operating temperature span. We present here internally wavelength stabilized lasers emitting ns optical pulses from an emission aperture between 30 μm and 100 μm with peak powers of tens of Watts at wavelengths around 905 nm. The vertical structure based on AlGaAs (confinement and cladding layers) and InGaAs (active quantum well) is especially optimized for pulsed operation with respect to the implementation of a surface Bragg grating with a high reflectivity. The fabricated 6 mm long distributed Bragg reflector (DBR) broad area (BA) lasers are electrically driven by an in-house developed high-speed unit generating 3 to 10 ns long nearly rectangular shaped current pulses with amplitudes of up to 250 A. Such lasers emit optical pulses with a peak power of more than 30 W at 95 A pulse current up to a temperature of 85°C with a wavelength shift as low as 65 pm/K and a lateral beam propagation factor less than 10. The influence of the lateral aperture width and the pulse length on the beam quality will be shown. A monolithic integration of 3 DBR BA lasers on a single chip whose emission can be combined into a single beam raises the output power to more than 100 W.

Space Solar Power Technology for Lunar Polar Applications

Science.gov (United States)

Henley, Mark W.; Howell, Joe T.

2004-01-01

The technology for Laser-Photo-Voltaic Wireless Power Transistor (Laser-PV WPT) is being developed for lunar polar applications by Boeing and NASA Marshall Space Center. A lunar polar mission could demonstrate and validate Laser-PV WPT and other SSP technologies, while enabling access to cold, permanently shadowed craters that are believed to contain ice. Crater may hold frozen water and other volatiles deposited over billion of years, recording prior impact event on the moon (and Earth). A photo-voltaic-powered rover could use sunlight, when available, and laser light, when required, to explore a wide range of lunar terrain. The National Research Council recently found that a mission to the moon's south pole-Aitkir basin has priority for space science

Optimized transmission-line impedance transformers for petawatt-class pulsed-power accelerators

Directory of Open Access Journals (Sweden)

D. R. Welch

2008-03-01

Full Text Available We have developed 1D analytic and 2D fully electromagnetic models of radial transmission-line impedance transformers. The models have been used to quantify the power-transport efficiency and pulse sharpening of such transformers as a function of voltage pulse width and impedance profile. For the cases considered, we find that in the limit as Γ→0 (where Γ is the ratio of the pulse width to the one-way transit time of the transformer, the transport efficiency is maximized when the impedance profile is exponential. As Γ increases from zero, the optimum profile gradually deviates from an exponential. A numerical procedure is presented that determines the optimum profile for a given pulse shape and width. The procedure can be applied to optimize the design of impedance transformers used in petawatt-class pulsed-power accelerators.

Effect of power modulation on properties of pulsed capacitively coupled radiofrequency discharges

International Nuclear Information System (INIS)

Samara, V; Bowden, M D; Braithwaite, N St J

2010-01-01

We describe measurements of plasma properties of pulsed, low pressure, capacitively coupled discharges operated in argon. The study aims to determine the effect of modulating the radiofrequency power during the discharge part of the pulse cycle. Measurements of local electron density and optical emission were made in capacitively coupled rf discharges generated in a Gaseous Electronics Conference (GEC) reference reactor. Gas pressure was in the range 7-70 Pa, rf power in the range 1-100 W and pulse durations in the range 10 μs-100 ms. The results indicate that the ignition and afterglow decay processes in pulsed discharges can be controlled by modulating the shape of applied radiofrequency pulse.

Basic science with pulsed power ampersand some off-the-wall ideas

International Nuclear Information System (INIS)

Solem, J.C.

1995-01-01

This paper discusses aspects of pulsed power for use in basic research, with a principal emphasis on ATLAS, a planned 36-MJ pulsed-power machine with a circular architechture designed primarily for z-pinch implosion of cylindrical foils. The objective of the paper is to give an overview and touch on subjects which might test the limits of this technology

Exploring new frontiers in the pulsed power laboratory: Recent progress

Directory of Open Access Journals (Sweden)

S. Adamenko

2015-01-01

Full Text Available One of the most fundamental processes in the Universe, nucleosynthesis of elements drives energy production in stars as well as the creation of all atoms heavier than hydrogen. To harness this process and open new ways for energy production, we must recreate some of the extreme conditions in which it occurs. We present results of experiments using a pulsed power facility to induce collective nuclear interactions producing stable nuclei of virtually every element in the periodic table. A high-power electron beam pulse striking a small metallic target is used to create the extreme dynamic environment. Material analysis studies detect an anomalously high presence of new chemical elements in the remnants of the exploded target supporting theoretical conjectures of the experiment. These results provide strong motivation to continue our research looking for additional proofs that heavy element nucleosynthesis is possible in pulsed power laboratory.

Development of Compact Ozonizer with High Ozone Output by Pulsed Power

Science.gov (United States)

Tanaka, Fumiaki; Ueda, Satoru; Kouno, Kanako; Sakugawa, Takashi; Akiyama, Hidenori; Kinoshita, Youhei

Conventional ozonizer with a high ozone output using silent or surface discharges needs a cooling system and a dielectric barrier, and therefore becomes a large machine. A compact ozonizer without the cooling system and the dielectric barrier has been developed by using a pulsed power generated discharge. The wire to plane electrodes made of metal have been used. However, the ozone output was low. Here, a compact and high repetition rate pulsed power generator is used as an electric source of a compact ozonizer. The ozone output of 6.1 g/h and the ozone yield of 86 g/kWh are achieved at 500 pulses per second, input average power of 280 W and an air flow rate of 20 L/min.

Applications: REP-rate pulse power technology

International Nuclear Information System (INIS)

Anon.

1979-01-01

Research on the following topics is discussed: (1) REP-rate pulse power technology, (2) RTF-I, 300-J, 100-pps test facility experiments, (3) transformer development, (4) reactor system studies, (5) general conceptual design, (6) economic considerations, (7) specific reactor designs, (8) low-current density diode physics studies, and (9) plasma injected, microsecond, E-beam diodes

X-Parameter Based Modelling of Polar Modulated Power Amplifiers

DEFF Research Database (Denmark)

Wang, Yelin; Nielsen, Troels Studsgaard; Sira, Daniel

2013-01-01

X-parameters are developed as an extension of S-parameters capable of modelling non-linear devices driven by large signals. They are suitable for devices having only radio frequency (RF) and DC ports. In a polar power amplifier (PA), phase and envelope of the input modulated signal are applied...... at separate ports and the envelope port is neither an RF nor a DC port. As a result, X-parameters may fail to characterise the effect of the envelope port excitation and consequently the polar PA. This study introduces a solution to the problem for a commercial polar PA. In this solution, the RF-phase path...... PA for simulations. The simulated error vector magnitude (EVM) and adjacent channel power ratio (ACPR) were compared with the measured data to validate the model. The maximum differences between the simulated and measured EVM and ACPR are less than 2% point and 3 dB, respectively....

Production of ozone using nanosecond short pulsed power

OpenAIRE

Shimomura, N.; Wakimoto, M.; Togo, H.; Namihira, Takao; Akiyama, Hidenori; ナミヒラ, タカオ; アキヤマ, ヒデノリ; 浪平, 隆男; 秋山, 秀典

2003-01-01

Production of ozone is one of the most typical industrial and commercial applications of electrical discharge. The demand of ozone will be increasing for wholesome and environment-friendly sterilizations. The production of ozone using the pulsed power discharge will apply electron accelerations around the head of streamer discharge. The breakdowns in reactor, however, often limit the efficient production. The pulse shape should be controlled for dimension of the reactor. On the other hand, th...

Control of the spin polarization of photoelectrons/photoions using short laser pulses

International Nuclear Information System (INIS)

Nakajima, Takashi

2004-01-01

We present a generic pump-probe scheme to control spin polarization of photoelectrons/photoions by short laser pulses. By coherently exciting fine structure manifolds of a multi-valence-electron system by the pump laser, a superposition of fine structure states is created. Since each fine structure state can be further decomposed into a superposition of various spin states of valence electrons, each spin component evolves differently in time. This means that varying the time delay between the pump and probe lasers leads to the control of spin states. Specific theoretical results are presented for two-valence-electron atoms, in particular for Mg, which demonstrate that not only the degree of spin polarization but also its sign can be manipulated through time delay. Since the underline physics is rather general and transparent, the presented idea may be potentially applied to nanostructures such as quantum wells and quantum dots

High power, repetitive stacked Blumlein pulse generators

Energy Technology Data Exchange (ETDEWEB)

Davanloo, F; Borovina, D L; Korioth, J L; Krause, R K; Collins, C B [Univ. of Texas at Dallas, Richardson, TX (United States). Center for Quantum Electronics; Agee, F J [US Air Force Phillips Lab., Kirtland AFB, NM (United States); Kingsley, L E [US Army CECOM, Ft. Monmouth, NJ (United States)

1997-12-31

The repetitive stacked Blumlein pulse power generators developed at the University of Texas at Dallas consist of several triaxial Blumleins stacked in series at one end. The lines are charged in parallel and synchronously commuted with a single switch at the other end. In this way, relatively low charging voltages are multiplied to give a high discharge voltage across an arbitrary load. Extensive characterization of these novel pulsers have been performed over the past few years. Results indicate that they are capable of producing high power waveforms with rise times and repetition rates in the range of 0.5-50 ns and 1-300 Hz, respectively, using a conventional thyratron, spark gap, or photoconductive switch. The progress in the development and use of stacked Blumlein pulse generators is reviewed. The technology and the characteristics of these novel pulsers driving flash x-ray diodes are discussed. (author). 4 figs., 5 refs.

Pulsed power for fusion

International Nuclear Information System (INIS)

Martin, T.H.

1976-01-01

A review which traces the development of high power pulsed accelerators from the original inception at the Atomic Weapons Research Establishment, Aldermaston, England, for Bremsstrahlung output, through the low impedance accelerators, to the double-sided accelerators for fusion will be given. Proto II is presently being assembled at Sandia and preliminary testing on the Marx has been completed. Examples of various techniques will be shown from Sandia accelerators. Requirements for accelerators capable of achieving fusion levels will be developed and problem areas outlined. The diode insulator flashover problem presently limits the maximum current available from the accelerators

Effects of pulse frequency of input power on the physical and chemical properties of pulsed streamer discharge plasmas in water

Science.gov (United States)

Ruma; Lukes, P.; Aoki, N.; Spetlikova, E.; Hosseini, S. H. R.; Sakugawa, T.; Akiyama, H.

2013-03-01

A repetitive pulsed-power modulator, which employs a magnetic pulse compression circuit with a high-speed thyristor switch, was used to study the effects of the pulse repetition rate of input power on the physical and chemical properties of pulsed discharges in water. Positive high-voltage pulses of 20 kV with repetition rates of up to 1 kHz were used to generate a discharge in water using the point-to-plane electrode geometry. By varying the pulse repetition rate, two distinct modes of the discharge plasma were formed in water. The first mode was characterized by the formation of a corona-like discharge propagating through water in the form of streamer channels. The second mode was formed typically above 500 Hz, when the formation of streamer channels in water was suppressed and all plasmas occurred inside a spheroidal aggregate of very fine gas bubbles surrounding the tip of the high-voltage electrode. The production of hydrogen peroxide, degradation of organic dye Acid Orange 7 (AO7) and inactivation of bacteria Escherichia coli by the discharge in water were studied under different discharge plasma modes in dependence on the pulse repetition rate of input power. The efficiency of both chemical and biocidal processes induced by the plasma in water decreased significantly with pulse repetition rates above 500 Hz.

Effects of pulse frequency of input power on the physical and chemical properties of pulsed streamer discharge plasmas in water

International Nuclear Information System (INIS)

Ruma; Aoki, N; Hosseini, S H R; Sakugawa, T; Akiyama, H; Lukes, P; Spetlikova, E

2013-01-01

A repetitive pulsed-power modulator, which employs a magnetic pulse compression circuit with a high-speed thyristor switch, was used to study the effects of the pulse repetition rate of input power on the physical and chemical properties of pulsed discharges in water. Positive high-voltage pulses of 20 kV with repetition rates of up to 1 kHz were used to generate a discharge in water using the point-to-plane electrode geometry. By varying the pulse repetition rate, two distinct modes of the discharge plasma were formed in water. The first mode was characterized by the formation of a corona-like discharge propagating through water in the form of streamer channels. The second mode was formed typically above 500 Hz, when the formation of streamer channels in water was suppressed and all plasmas occurred inside a spheroidal aggregate of very fine gas bubbles surrounding the tip of the high-voltage electrode. The production of hydrogen peroxide, degradation of organic dye Acid Orange 7 (AO7) and inactivation of bacteria Escherichia coli by the discharge in water were studied under different discharge plasma modes in dependence on the pulse repetition rate of input power. The efficiency of both chemical and biocidal processes induced by the plasma in water decreased significantly with pulse repetition rates above 500 Hz. (paper)

Developing a Methodology for Elaborating a Pulsed Optical Safety Area for High Power Laser Diodes

National Research Council Canada - National Science Library

Yankov, Plamen

2006-01-01

The laser diodes are efficient sources of optical radiation. The maximum optical peak power depends on the pulse duration of the driving current pulse - reducing the pulse duration the safety peak power is increased...

Fast SMES for generation of high power pulses

International Nuclear Information System (INIS)

Juengst, K.P.; Salbert, H.

1996-01-01

A technique for generation of high power pulses based on a fast SMES has been developed and a model of a power modulator for linear accelerators was built. The basic function of the modulator that generates 2 ms long, approximately 1 MW power pulses at a repetition rate of 10 Hz is described in this paper. A modular construction of the SMES that consists of up to six coils has been chosen to meet the demands of several applications in high energy physics and energy distribution. The rate of change of magnetic field achieved during ramping of the magnet was more than 60 T/s without a quench. The magnet was designed with respect to the high AC losses during repetitive ramping of the SMES. The suitability of mixed matrix superconductors instead of more expensive net frequency wires for this kind of AC stress was investigated. The applied mixed matrix Cu/CuNi/NbTi wire and the construction of a single coil is described

Influence of the parameters of supplying pulses and polarization voltage on the signal and shape of current characteristics of the electron capture detector

International Nuclear Information System (INIS)

Lasa, J.; Sliwka, I.; Drozdowicz, B.

1989-01-01

The paper contains results of measurements of current characteristics and of the signal for the constant concentration of freon F-11 of the ECD supplied with pulse voltage of changeable time of pulse duration t p , amplitude U 1 and the time of pulse repetition t r . In the course of measurements the detector worked at temperature 573 K with the additional constant polarization voltage. The polarization voltage has been observed to cause the effect of hypercoulometry. The presented mathematical analysis helps to determine the values of the coefficient of efficiency of electron capture p, the coefficient of electron loss k D , the coefficient of collecting of electric charges by the anode k' 3 and the coefficient of collecting of electric charges by the detector cathode k u . The coefficients are determined on the basis of experimental measurements. An attempt of physical interpretation of calculated values of these coefficients and their dependence on the parameters of the pulses supplying the detector has been presented. This interpretation requires the assumption that in some pulse periods t r the concentration of positive ions in the detector considerably exceeds concentration n 0 + = √a xα e /V, where a is an efficiency of the carrier gas ionization, α e is the coefficient of the electron-ion recombination and V is the detector volume. This statement helping to describe the effects observed in the electron capture polarized by voltage U a contradicts the recognized concept that the concentration of positive ions in the detector does not exceed the concentration n 0 + . The paper shows that the detector of the cylindrical construction, supplied with a pulse voltage can be used for coulometric measurements and the voltage polarizing the cathode can cause an effect of hypercoulometry. 33 figs., 9 refs. (author)

Modeling generalized interline power-flow controller (GIPFC using 48-pulse voltage source converters

Directory of Open Access Journals (Sweden)

Amir Ghorbani

2018-05-01

Full Text Available Generalized interline power-flow controller (GIPFC is one of the voltage-source controller (VSC-based flexible AC transmission system (FACTS controllers that can independently regulate the power-flow over each transmission line of a multiline system. This paper presents the modeling and performance analysis of GIPFC based on 48-pulsed voltage-source converters. This paper deals with a cascaded multilevel converter model, which is a 48-pulse (three levels voltage source converter. The voltage source converter described in this paper is a harmonic neutralized, 48-pulse GTO converter. The GIPFC controller is based on d-q orthogonal coordinates. The algorithm is verified using simulations in MATLAB/Simulink environment. Comparisons between unified power flow controller (UPFC and GIPFC are also included. Keywords: Generalized interline power-flow controller (GIPFC, Voltage source converter (VCS, 48-pulse GTO converter

High-Voltage, Multiphasic, Nanosecond Pulses to Modulate Cellular Responses.

Science.gov (United States)

Ryan, Hollie A; Hirakawa, Shinji; Yang, Enbo; Zhou, Chunrong; Xiao, Shu

2018-04-01

Nanosecond electric pulses are an effective power source in plasma medicine and biological stimulation, in which biophysical responses are governed by peak power and not energy. While uniphasic nanosecond pulse generators are widely available, the recent discovery that biological effects can be uniquely modulated by reversing the polarity of nanosecond duration pulses calls for the development of a multimodal pulse generator. This paper describes a method to generate nanosecond multiphasic pulses for biomedical use, and specifically demonstrates its ability to cancel or enhance cell swelling and blebbing. The generator consists of a series of the fundamental module, which includes a capacitor and a MOSFET switch. A positive or a negative phase pulse module can be produced based on how the switch is connected. Stacking the modules in series can increase the voltage up to 5 kV. Multiple stacks in parallel can create multiphase outputs. As each stack is independently controlled and charged, multiphasic pulses can be created to produce flexible and versatile pulse waveforms. The circuit topology can be used for high-frequency uniphasic or biphasic nanosecond burst pulse production, creating numerous opportunities for the generator in electroporation applications, tissue ablation, wound healing, and nonthermal plasma generation.

Nonlinear Polarization Rotation-Based Mode-Locked Erbium-Doped Fiber Laser with Three Switchable Operation States

International Nuclear Information System (INIS)

Tiu Zian Cheak; Tan Sin Jin; Zarei Arman; Ahmad Harith; Harun Sulaiman Wadi

2014-01-01

A simple mode-locked erbium-doped fiber laser (EDFL) with three switchable operation states is proposed and demonstrated based on nonlinear polarization rotation. The EDFL generates a stable square pulse at a third harmonic pulse repetition rate of 87 kHz as the 1480 nm pump power increases from the threshold of 17.5 mW to 34.3 mW. The square pulse duration increases from 105 ns to 245 ns as the pump power increases within this region. The pulse operation switches to the second operation state as the pump power is varied from 48.2 mW to 116.7 mW. The laser operates at a fundamental repetition rate of 29 kHz with a fixed pulse width of 8.5 μs within the pump power region. At a pump power of 116.7 mW, the average output power is 3.84 mW, which corresponds to the pulse energy of 131.5 nJ. When the pump power continues to increase, the pulse train experiences unstable oscillation before it reaches the third stable operation state within a pump power region of 138.9 mW to 145.0 mW. Within this region, the EDFL produces a fixed pulse width of 2.8 μs and a harmonic pulse repetition rate of 58 kHz. (fundamental areas of phenomenology(including applications))

High-voltage pulse generator for electron gun power supply

International Nuclear Information System (INIS)

Korenev, S.A.; Enchevich, I.B.; Mikhov, M.K.

1987-01-01

High-voltage pulse generator with combined capacitive and inductive energy storages for electron gun power supply is described. Hydrogen thyratron set in a short magnetic lense is a current breaker. Times of current interruption in thyratrons are in the range from 100 to 300 ns. With 1 kV charging voltage of capacitive energy storage 25 kV voltage pulse is obtained in the load. The given high-voltage pulse generator was used for supply of an electron gun generating 10-30 keV low-energy electron beam

Three-dimensional electromagnetic model of the pulsed-power Z-pinch accelerator

Directory of Open Access Journals (Sweden)

D. V. Rose

2010-01-01

Full Text Available A three-dimensional, fully electromagnetic model of the principal pulsed-power components of the 26-MA ZR accelerator [D. H. McDaniel et al., in Proceedings of the 5th International Conference on Dense Z-Pinches (AIP, New York, 2002, p. 23] has been developed. This large-scale simulation model tracks the evolution of electromagnetic waves through the accelerator’s intermediate-storage capacitors, laser-triggered gas switches, pulse-forming lines, water switches, triplate transmission lines, and water convolute to the vacuum insulator stack. The insulator-stack electrodes are coupled to a transmission-line circuit model of the four-level magnetically insulated vacuum-transmission-line section and double-post-hole convolute. The vacuum-section circuit model is terminated by a one-dimensional self-consistent dynamic model of an imploding z-pinch load. The simulation results are compared with electrical measurements made throughout the ZR accelerator, and are in good agreement with the data, especially for times until peak load power. This modeling effort demonstrates that 3D electromagnetic models of large-scale, multiple-module, pulsed-power accelerators are now computationally tractable. This, in turn, presents new opportunities for simulating the operation of existing pulsed-power systems used in a variety of high-energy-density-physics and radiographic applications, as well as even higher-power next-generation accelerators before they are constructed.

Electrical Tree Initiation and Growth in Silicone Rubber under Combined DC-Pulse Voltage

Directory of Open Access Journals (Sweden)

Tao Han

2018-03-01

Full Text Available Electrical tree is a serious threat to silicone rubber (SIR insulation and can even cause breakdown. Electrical trees under alternating current (AC and direct current (DC voltage have been widely researched. While there are pulses in high-voltage direct current (HVDC cables under operating conditions caused by lightning and operating overvoltage in the power system, little research has been reported about trees under combined DC-pulse voltage. Their inception and growth mechanism is still not clear. In this paper, electrical trees are studied under several types of combined DC-pulse voltage. The initiation and growth process was recorded by a digital microscope system. The experimental results indicate that the inception pulse voltage is different under each voltage type and is influenced by the combined DC. The initial tree has two structures, determined by the pulse polarity. With increased DC prestressing time, tree inception pulse voltage with the same polarity is clearly decreased. Moreover, a special initial bubble tree was observed after the prestressing DC.

SBS pulse compression for excimer inertial fusion energy drivers

Energy Technology Data Exchange (ETDEWEB)

Linford, G.J. [TRW Space and Electronics Group, Redondo Beach, CA (United States). Space and Technology Div.

1994-12-31

A key requirement for the development of commercial fusion power plants utilizing inertial confinement fusion (ICF) as a source of thermonuclear power is the availability of reliable, efficient laser drivers. These laser drivers must be capable of delivering UV optical pulses having energies of the order of 5MJ to cryogenic deuterium-tritium (D/T) ICF targets. The current requirements for laser ICF target irradiation specify the laser wavelength, {lambda} ca. 250 nm, pulse duration, {tau}{sub p} ca. 6 ns, bandwidth, {Delta}{lambda} ca. 0.1 nm, polarization state, etc. Excimer lasers are a leading candidate to fill these demanding ICF driver requirements. However, since excimer lasers are not storage lasers, the excimer laser pulse duration, {tau}{sub pp}, is determined primarily by the length of the excitation pulse delivered to the excimer laser amplifier. Pulsed power associated with efficiently generating excimer laser pulses has a time constant, {tau}{sub pp} which falls in the range, 30 {tau}{sub p}<{tau}{sub pp}<100{tau}{sub p}. As a consequence, pulse compression is needed to convert the long excimer laser pulses to pulses of duration {tau}{sub p}. These main ICF driver pulses require, in addition, longer, lower power precursor pulses delivered to the ICF target before the arrival of the main pulse. Although both linear and non-linear optical (NLO) pulse compression techniques have been developed, computer simulations have shown that a ``chirped,`` self-seeded, stimulated Brillouin scattering (SBS) pulse compressor cell using SF{sub 6} at a density, {rho} ca. 1 amagat can efficiently compress krypton fluoride (KrF) laser pulses at {lambda}=248 nm. In order to avoid the generation of output pulses substantially shorter than {tau}{sub p}, the optical power in the chirped input SBS ``seed`` beams was ramped. Compressed pulse conversion efficiencies of up to 68% were calculated for output pulse durations of {tau}{sub p} ca. ns.

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

International Nuclear Information System (INIS)

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

2011-01-01

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. (fast track communication)

Highly-nonlinear polarization-maintaining As2Se3-based photonic quasi-crystal fiber for supercontinuum generation

Science.gov (United States)

Zhao, Tongtong; Lian, Zhenggang; Benson, Trevor; Wang, Xin; Zhang, Wan; Lou, Shuqin

2017-11-01

We propose an As2Se3-based photonic quasi-crystal fiber (PQF) with high nonlinearity and birefringence. By optimizing the structure parameters, a nonlinear coefficient up to 2079 W-1km-1 can be achieved at the wavelength of 2 μm; the birefringence reaches up to the order of 10-2 due to the introduction of large circular air holes in the cladding. Using an optical pulse with a peak power of 6 kW, a pulse width of 150 fs, and a central wavelength of 2.94 μm as the pump pulse, a mid-infrared polarized supercontinuum is obtained by using a 15 mm long PQF. The spectral width for x- and y-polarizations covers 1 μm-10.2 μm and 1 μm-12.5 μm, respectively. The polarization state can be well maintained when the incident angle of the input pulse changes within ±2°. The proposed PQF, with high nonlinear coefficient and birefringence, has potential applications in mid-infrared polarization-maintaining supercontinuum generation.

Implications of electron attachment to highly-excited states in pulsed-power discharges

International Nuclear Information System (INIS)

Pinnaduwage, L.A.; Univ. of Tennessee, Knoxville, TN

1997-01-01

The author points out the possible implications of electron attachment to highly-excited states of molecules in two pulsed power technologies. One involves the pulsed H 2 discharges used for the generation of H ion beams for magnetic fusion energy and particle accelerators. The other is the power modulated plasma discharges used for material processing

Pulsed power bibliography. Volume 2. Annotated bibliography. Final report

Energy Technology Data Exchange (ETDEWEB)

Bemesderfer, J.; Druce, R.L.; Frantz, B.; Guenther, A.H.; Kristiansen, M.

1983-08-01

Pulsed power and high-voltage technologies are playing an ever increasing role in weapons' effects simulation, fusion power research, power distribution, materials processing and medical research. It is a rapidly expanding field of applied physics as evidenced by the growth in published literature. Three years ago, the Air Force Weapons Laboratory (AFWL) initiated a project to compile a computerized data base of pulsed power research papers. The data base is stored on our IBM System 2000. This AFWL Technical Report is the first release of the bibliography to date. It contains about 2,500 full bibliographic citations, original sources, availability, key words and abstracts. There are three indices: Subject, Personal Author, and Corporate. There are 30 main subject headings, from Breakdown Studies to Switching. Volume II contains the citations. In addition to these entries, the data base contains about 7,500 additional titles. As these titles are added to the full bibliography, they will be published.

Influence of Power Pulse Parameters on the Microstructure and Properties of the AlCrN Coatings by a Modulated Pulsed Power Magnetron Sputtering

Directory of Open Access Journals (Sweden)

Jun Zheng

2017-11-01

Full Text Available In this study, AlCrN coatings were deposited using modulated pulsed power magnetron sputtering (MPPMS with different power pulse parameters by varying modulated pulsed power (MPP charge voltages (350 to 550 V. The influence of power pulse parameters on the microstructure, mechanical properties and thermal stability of the coatings was investigated. The results indicated that all the AlCrN coatings exhibited a dense columnar microstructure. Higher charge voltage could facilitate a denser coating microstructure. As the charge voltage increased up to 450 V or higher, the microvoids along the column boundaries disappeared and the coatings became fully dense. The main phase in the AlCrN coatings was the c-(Al, CrN solid solution phase with NaCl-type phase structure. A diffraction peak of the h-AlN phase was detected at a 2θ of around 33°, when the charge voltage was higher than 500 V. The hardness of the AlCrN coatings varied as a function of charge voltage. The maximum value of the hardness (30.8 GPa was obtained at 450 V. All the coatings showed good thermal stability and maintained their structure and mechanical properties unchanged up to 800 °C during vacuum annealing. However, further increasing the annealing temperature to 1000 °C resulted in apparent change in the microstructure and decrease in the hardness. The charge voltages also showed a significant influence on the high-temperature tribological behavior of the coatings. The coating deposited at the charge voltage of 550 V exhibited excellent tribological properties with a low friction coefficient.

MFTF 230 kV pulsed power substation

International Nuclear Information System (INIS)

Wilson, J.H.

1979-01-01

The Mirror Fusion Test Facility (MFTF) currently under construction at the Lawrence Livermore Laboratory includes a Sustaining Neutral Beam Power Supply System (SNBPSS) consisting of 24 power-supply sets. The System will operate in long pulses (initially .5 seconds and eventually 30 seconds) at high power (200 MW), which will necessitate a large source of ac power. To meet this requirement, a new 230-kV substation is also being built at LLL. The constraints of cost, equipment protection, short operating lifetime (10 years), and reliability dictated a unique substation design. Its unusual features include provisions for fast fault detection and tripping, a capability for limiting ground fault current, low impedance, and economical design

Surface modification of β-Type titanium alloy by electrochemical potential pulse polarization

International Nuclear Information System (INIS)

Fujimoto, Shinji; Raman, Vedarajan; Tsuchiya, Hiroaki

2009-01-01

In the present work, we report the formation of a porous oxide/hydroxide surface layer on the Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy achieved by the combination of an alkali immersion and a potential pulse polarisation process. The alkali treatment has been employed for pure titanium to produce amorphous and porous layer prior to hydroxyapatite (HAp) growth. But, in the case of TNTZ, immersion in 5M NaOH at the open circuit potential (OCP) at 60 deg. C for 24 hours, did not yield any uniform layer, instead a thick deposited layer with highly cracked one. The cracks were attributed to the growth of a tantalum enriched particulate. In order to avoid the crack formation, the electrochemical behaviour of the alloy and the pure alloying elements (Ti, Nb, Ta and Zr) was investigated to produce a uniform surface with the application of a square wave modulated potential pulse polarization, leading to the formation of a relatively uniform porous layer on the alloy.

Surface modification of {beta}-Type titanium alloy by electrochemical potential pulse polarization

Energy Technology Data Exchange (ETDEWEB)

Fujimoto, Shinji; Raman, Vedarajan; Tsuchiya, Hiroaki [Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)], E-mail: fujimoto@mat.eng.osaka-u.ac.jp

2009-05-01

In the present work, we report the formation of a porous oxide/hydroxide surface layer on the Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy achieved by the combination of an alkali immersion and a potential pulse polarisation process. The alkali treatment has been employed for pure titanium to produce amorphous and porous layer prior to hydroxyapatite (HAp) growth. But, in the case of TNTZ, immersion in 5M NaOH at the open circuit potential (OCP) at 60 deg. C for 24 hours, did not yield any uniform layer, instead a thick deposited layer with highly cracked one. The cracks were attributed to the growth of a tantalum enriched particulate. In order to avoid the crack formation, the electrochemical behaviour of the alloy and the pure alloying elements (Ti, Nb, Ta and Zr) was investigated to produce a uniform surface with the application of a square wave modulated potential pulse polarization, leading to the formation of a relatively uniform porous layer on the alloy.

Limitations of power conversion systems under transient loads and impact on the pulsed tokamak power reactor

International Nuclear Information System (INIS)

Sager, G.T.; Wong, C.P.C.; Kapich, D.D.; McDonald, C.F.; Schleicher, R.W.

1993-11-01

The impact of cyclic loading of the power conversion system of a helium-cooled, pulsed tokamak power plant is assessed. Design limits of key components of heat transport systems employing Rankie and Brayton thermodynamic cycles are quantified based on experience in gas-cooled fission reactor design and operation. Cyclic loads due to pulsed tokamak operation are estimated. Expected performance of the steam generator is shown to be incompatible with pulsed tokamak operation without load leveling thermal energy storage. The close cycle gas turbine is evaluated qualitatively based on performance of existing industrial and aeroderivative gas turbines. Advances in key technologies which significantly improve prospects for operation with tokamak fusion plants are reviewed

Femtosecond pulse shaping using the geometric phase.

Science.gov (United States)

Gökce, Bilal; Li, Yanming; Escuti, Michael J; Gundogdu, Kenan

2014-03-15

We demonstrate a femtosecond pulse shaper that utilizes polarization gratings to manipulate the geometric phase of an optical pulse. This unique approach enables circular polarization-dependent shaping of femtosecond pulses. As a result, it is possible to create coherent pulse pairs with orthogonal polarizations in a 4f pulse shaper setup, something until now that, to our knowledge, was only achieved via much more complex configurations. This approach could be used to greatly simplify and enhance the functionality of multidimensional spectroscopy and coherent control experiments, in which multiple coherent pulses are used to manipulate quantum states in materials of interest.

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

DEFF Research Database (Denmark)

Michieletto, Mattia; Johansen, Mette Marie; Lyngsø, Jens Kristian

2015-01-01

We demonstrated robust and bend insensitive fiber delivery of high power pulsed laser with diffraction limited beam quality for two different kind of hollow core photonic band gap fibers......We demonstrated robust and bend insensitive fiber delivery of high power pulsed laser with diffraction limited beam quality for two different kind of hollow core photonic band gap fibers...

High beam quality and high energy short-pulse laser with MOPA

Science.gov (United States)

Jin, Quanwei; Pang, Yu; Jiang, JianFeng; Tan, Liang; Cui, Lingling; Wei, Bin; Sun, Yinhong; Tang, Chun

2018-03-01

A high energy, high beam quality short-pulse diode-pumped Nd:YAG master oscillator power-amplifier (MOPA) laser with two amplifier stages is demonstrated. The two-rod birefringence compensation was used as beam quality controlling methods, which presents a short-pulse energy of 40 mJ with a beam quality value of M2 = 1.2 at a repetition rate of 400Hz. The MOPA system delivers a short-pulse energy of 712.5 mJ with a pulse width of 12.4 ns.The method of spherical aberration compensation is improved the beam quality, a M2 factor of 2.3 and an optical-to-optical efficiency of 27.7% is obtained at the maximum laser out power.The laser obtained 1.4J out energy with polarization integration.

High-efficiency resonant rf spin rotator with broad phase space acceptance for pulsed polarized cold neutron beams

Directory of Open Access Journals (Sweden)

P.-N. Seo

2008-08-01

Full Text Available High precision fundamental neutron physics experiments have been proposed for the intense pulsed spallation neutron beams at JSNS, LANSCE, and SNS to test the standard model and search for new physics. Certain systematic effects in some of these experiments have to be controlled at the few ppb level. The NPDGamma experiment, a search for the small parity-violating γ-ray asymmetry A_{γ} in polarized cold neutron capture on parahydrogen, is one example. For the NPDGamma experiment we developed a radio-frequency resonant spin rotator to reverse the neutron polarization in a 9.5  cm×9.5  cm pulsed cold neutron beam with high efficiency over a broad cold neutron energy range. The effect of the spin reversal by the rotator on the neutron beam phase space is compared qualitatively to rf neutron spin flippers based on adiabatic fast passage. We discuss the design of the spin rotator and describe two types of transmission-based neutron spin-flip efficiency measurements where the neutron beam was both polarized and analyzed by optically polarized ^{3}He neutron spin filters. The efficiency of the spin rotator was measured at LANSCE to be 98.8±0.5% for neutron energies from 3 to 20 meV over the full phase space of the beam. Systematic effects that the rf spin rotator introduces to the NPDGamma experiment are considered.

High-power pulsed lasers

International Nuclear Information System (INIS)

Holzrichter, J.F.

1980-01-01

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

Developments of compact pulsed-power system toward X-ray sources

Directory of Open Access Journals (Sweden)

Miyamoto Takuya

2013-11-01

Full Text Available In order to generate X-rays from X-pinch, the peak current and current-rising time required are estimated to be 100 kA and 100 ns, respectively. To obtain these parameters, we developed a pulsed-power system, which consists of a parallelized pulse-forming network (PFN. The 20 PFN modules of the system were driven at a charging voltage of 20 kV by a thin copper wire of load resistance. The results showed that the current and current-rising time are 18 kA and 107 ns, respectively. The wire/plasma temperature is 6.9 eV. The pulsed-power system is expected to generate X-rays from X-pinch by the proposed system. This can be achieved by raising the voltage and increasing the number of PFN modules.

Atlas Pulsed Power System: a Driver for Multi-Megagauss Fields

International Nuclear Information System (INIS)

Cochrane, J.C.; Bartsch, R.R.; Bennett, G.A.; Bowman, D.W.; Davis, H.A.; Ekdahl, C.A.; Gribble, R.F.; Kimerly, H.J.; Nielsen, K.E.; Parsons, W.M.; Paul, J.D.; Scudder, D.W.; Trainor, R.J.; Thompson, M.C.; Watt, R.G.

1998-01-01

Atlas is a pulsed power machine designed for hydrodynamic experiments for the Los Alamos High Energy Density Physics Experimental program. It is presently under construction and should be operational in late 2000. Atlas will store 23 MJ at an erected voltage of 240 kV. This will produce a current of 30 MA into a static load and as much as 32 MA into a dynamic load. The current pulse will have a rise time of approximately5micros and will produce a magnetic field driving the impactor liner of several hundred Tesla at the target radius of one to two centimeters. The collision can produce shock pressures of approximately15 megabars. Design of the pulsed power system will be presented along with data obtained from the Atlas prototype Marx module

Laser accelerated protons captured and transported by a pulse power solenoid

OpenAIRE

Burris-Mog, T.; Harres, K.; Zielbauer, B.; Bagnoud, V.; Herrmannsdoerfer, T.; Roth, M.; Cowan, T. E.; Nürnberg, F.; Busold, S.; Bussmann, M.; Deppert, O.; Hoffmeister, G.; Joost, M.; Sobiella, M.; Tauschwitz, A.

2011-01-01

Using a pulse power solenoid, we demonstrate efficient capture of laser accelerated proton beams and the ability to control their large divergence angles and broad energy range. Simulations using measured data for the input parameters give inference into the phase-space and transport efficiencies of the captured proton beams. We conclude with results from a feasibility study of a pulse power compact achromatic gantry concept. Using a scaled target normal sheath acceleration spectrum, we prese...

Study of pulse stretching in high current power supplies using multipulse techniques

International Nuclear Information System (INIS)

Trendler, R.C.

1977-01-01

Considerable interest exists at Fermilab to increase the pulse width of the Neutrino Focusing Horn to permit an increase in beam spill length from twenty (20) microseconds to one (1) millisecond. Two techniques to do this were examined: (1) a high current transformer, and (2) increased bank capacitance using the multi-power supply technique. The transformer is the most straightforward conceptually; it is, however, a complicated device requiring sizable changes to the existing horn power supply. This alternative is briefly reviewed. The second scheme involves pulsing a 20 kv 200 ka power supply to establish the required load current and then maintaining this current by the sequential pulsing of a number of low voltage high current power supplies. This alternative is discussed in detail with the results of tests performed on the Fermilab Focusing Horn System

Generation of high-intensity sub-30 as pulses by inhomogeneous polarization gating technology in bowtie-shaped nanostructure

Science.gov (United States)

Feng, Liqiang; Feng, A. Yuanzi

2018-04-01

The generation of high-order harmonics and single attosecond pulses (SAPs) from He atom driven by the inhomogeneous polarization gating technology in a bowtie-shaped nanostructure is theoretically investigated. The results show that by the proper addition of bowtie-shaped nanostructure along the driven laser polarization direction, the harmonic emission becomes sensitive to the position of the laser field, and the harmonics emitted at the maximum orders that generate SAPs occur only at one side of the region inside the nanostructure. As a result, not only the harmonic cutoff can be extended, but also the modulations of the harmonics can be decreased, showing a carrier envelope phase independent harmonic cutoff with a bandwidth of 310 eV. Further, with the proper introduction of an ultraviolet pulse, the harmonic yield can be enhanced by 2 orders of magnitude. Finally, by the Fourier transformation of the selected harmonics, some SAPs with a full width at half maximum of sub-30 as can be obtained.

Performance of the SLC polarized electron source with high polarization

International Nuclear Information System (INIS)

Clendenin, J.E.; Alley, R.K.; Aoyagi, H.

1993-04-01

For the 1992 operating cycle of the SLAC Linear Collider (SLC), the polarized electron source (PES) during its maiden run successfully met the pulse intensity and overall efficiency requirements of the SLC. However, the polarization of the bulk GaAs cathode was low (∼27%) and the pulse-to-pulse stability was marginal. We have shown that adequate charge for the SLC can be extracted from a strained layer cathode having P e ∼80% even though the quantum efficiency (QE) is - beam stability. The performance of the PES during the 1993 SLC operating cycle with these and other improvements is discussed

Characterization of a high-power/current pulsed magnetized arc discharge

NARCIS (Netherlands)

Zielinski, J. J.; van der Meiden, H. J.; Morgan, T. W.; D.C. Schram,; De Temmerman, G.

2012-01-01

A high-power pulsed magnetized arc discharge has been developed to allow the superimposition of a dc plasma and a high-power plasma impulse with a single plasma source. A capacitor bank (8400 mu F) is parallel-coupled to the current regulated power supply. The current is transiently increased from

Characterization of a high-power/current pulsed magnetized arc discharge

NARCIS (Netherlands)

Zielinski, J.J.; Meiden, van der H.J.; Morgan, T.W.; Schram, D.C.; De Temmerman, G.C.

2012-01-01

A high-power pulsed magnetized arc discharge has been developed to allow the superimposition of a dc plasma and a high-power plasma impulse with a single plasma source. A capacitor bank (8400 µF) is parallel-coupled to the current regulated power supply. The current is transiently increased from its

Tomographic Particle Image Velocimetry using Pulsed, High Power LED Volume Illumination

OpenAIRE

Buchmann, N. A.; Willert, C.; Soria, J.

2011-01-01

This paper investigates the use of high-power light emitting diode (LED) illumination in Particle Image Velocimetry (PIV) as an alternative to traditional laser-based illumination. The solid-state LED devices can provide averaged radiant power in excess of 10W and by operating the LEDs with short current pulses, considerably higher than in continuous operation, light pulses of sufficient energy suitable for imaging micron-sized particles can be generated. The feasibility of this LED-based ill...

The nanosecond generator RG-1 with near-rectangular pulse

International Nuclear Information System (INIS)

Bulan, V.V.; Grabovskij, E.V.; Gribov, A.N.; Luzhnov, V.G.

1996-01-01

The 300 kV, 17 Ohm generator RG-1, which can deliver near-rectangular pulses with a pulse duration of 80 ns FWHM, is described. The polarity of the output pulse can be changed by a simple switch. The fast capacities of the Marx generator are used instead of the pulse forming line. Multi-spark gas switches were developed to decrease the inductance of the discharged circuit. The generator is supplied by a built-in high voltage source and its operation is controlled by a minicomputer. It is used the power supply-line 220 V. The RG-1 can be used in different modes of operation: gas discharge, particle beam formation, etc. (author). 4 figs., 3 refs

The nanosecond generator RG-1 with near-rectangular pulse

Energy Technology Data Exchange (ETDEWEB)

Bulan, V V; Grabovskij, E V; Gribov, A N; Luzhnov, V G [TRINITI, Troitsk (Russian Federation)

1997-12-31

The 300 kV, 17 Ohm generator RG-1, which can deliver near-rectangular pulses with a pulse duration of 80 ns FWHM, is described. The polarity of the output pulse can be changed by a simple switch. The fast capacities of the Marx generator are used instead of the pulse forming line. Multi-spark gas switches were developed to decrease the inductance of the discharged circuit. The generator is supplied by a built-in high voltage source and its operation is controlled by a minicomputer. It is used the power supply-line 220 V. The RG-1 can be used in different modes of operation: gas discharge, particle beam formation, etc. (author). 4 figs., 3 refs.

A simple sub-nanosecond ultraviolet light pulse generator with high repetition rate and peak power.

Science.gov (United States)

Binh, P H; Trong, V D; Renucci, P; Marie, X

2013-08-01

We present a simple ultraviolet sub-nanosecond pulse generator using commercial ultraviolet light-emitting diodes with peak emission wavelengths of 290 nm, 318 nm, 338 nm, and 405 nm. The generator is based on step recovery diode, short-circuited transmission line, and current-shaping circuit. The narrowest pulses achieved have 630 ps full width at half maximum at repetition rate of 80 MHz. Optical pulse power in the range of several hundreds of microwatts depends on the applied bias voltage. The bias voltage dependences of the output optical pulse width and peak power are analysed and discussed. Compared to commercial UV sub-nanosecond generators, the proposed generator can produce much higher pulse repetition rate and peak power.

High-power Yb-doped continuous-wave and pulsed fibre lasers

Indian Academy of Sciences (India)

2014-01-05

Jan 5, 2014 ... In this article, a review of Yb-doped CW and pulsed fibre lasers along with our study on self-pulsing dynamics in CW fibre lasers to find its role in high-power fibre laser development and the physical ... Solid State Laser Division, Raja Ramanna Centre for Advanced Technology, Indore 452 013, India ...

Counterintuitive angular shifts in the photoelectron momentum distribution for atoms in strong few-cycle circularly polarized laser pulses

DEFF Research Database (Denmark)

Martiny, Christian; Abu-Samha, Mahmoud; Madsen, Lars Bojer

2009-01-01

We solve the three-dimensional time-dependent Schrödinger equation for a three-cycle circularly polarized laser pulse interacting with an atom. The photoelectron momentum distributions show counterintuitive shifts, similar to those observed in a recent experiment (Eckle et al 2008 Science 322 1525...

Laser beam diagnostics for kilowatt power pulsed YAG laser

International Nuclear Information System (INIS)

Liu, Yi; Leong, Keng H.

1992-01-01

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

Fuel handling solutions to power pulse at Bruce NGS A

International Nuclear Information System (INIS)

Day, R.C.

1996-01-01

In response to the discovery of the power pulse problem in March of 1993, Bruce A has installed flow straightening shield plugs in the inner zone channels of all units to partially reduce the gap and gain an increase in reactor power to 75%. After review and evaluation of solutions to manage the gap, including creep compensators and long fuel bundles, efforts have focused on a different solution involving reordering the fuel bundles to reverse the burnup profile. This configuration is maintained by fuelling with the flow and providing better support to the highly irradiated downstream fuel bundles by changing the design of the outlet shield plug. Engineering changes to the fuel handling control system and outlet shield plug are planned to be implemented starting in June 1996, thereby eliminating the power pulse problem and restrictions on reactor operating power. (author). 2 refs., 1 tab., 2 figs

Fuel handling solutions to power pulse at Bruce NGS A

Energy Technology Data Exchange (ETDEWEB)

Day, R C [Ontario Hydro, Tiverton, ON (Canada). Bruce Nuclear Generating Station-A

1997-12-31

In response to the discovery of the power pulse problem in March of 1993, Bruce A has installed flow straightening shield plugs in the inner zone channels of all units to partially reduce the gap and gain an increase in reactor power to 75%. After review and evaluation of solutions to manage the gap, including creep compensators and long fuel bundles, efforts have focused on a different solution involving reordering the fuel bundles to reverse the burnup profile. This configuration is maintained by fuelling with the flow and providing better support to the highly irradiated downstream fuel bundles by changing the design of the outlet shield plug. Engineering changes to the fuel handling control system and outlet shield plug are planned to be implemented starting in June 1996, thereby eliminating the power pulse problem and restrictions on reactor operating power. (author). 2 refs., 1 tab., 2 figs.

Measurement and diagnosis system for 1.2 MV repetitive pulsed power source

International Nuclear Information System (INIS)

Li Yawei; Deng Jianjun; Xie Min; Feng Zongming; Liu Yuntao; Ma Chenggang

2010-01-01

In order to analyze the discharge performance and improve the design of the power system, a set of measurement and diagnosis system for the 1.2 MV repetitive pulsed power source, which supplies the drive power for a high power microwave source, has been designed by studying the high-voltage, high-current testing technology, data acquisition, signal processing, fault diagnosis, virtual instruments and electromagnetic compatibility technology, etc. A resistive-capacitive divider and a Rogowski coil are adopted in measurement; ADLINK corporation's PXI chips are used in data acquisition; data transmission system, condition monitoring and data analysis are developed by LabVIEW. This system can realize on-line monitoring and data analysis for the repetitive pulsed power source. (authors)

High-power test of S-band klystron for long-pulse operation

International Nuclear Information System (INIS)

Morii, Y.; Oshita, E.; Abe, S.; Keishi, T.; Tomimasu, T.; Ohkubo, Y.; Yoshinao, M.; Yonezawa, H.

1994-01-01

FELI(Free Electron Laser Research Institute, Inc.) is constructing a free electron laser facility covering from 20μm (infra red region) to 0.35μm (ultra violet region), using an S-band linac. The linac is commissioning now. An RF system of the linac for FELs is required of long pulse duration and high stability. S-band klystrons (TOSHIBA E3729) of the FELI linac are operated in three pulse operation modes (pulse width and peak RF power; 24μs-24MW, 12.5μs-34MW, 0.5μs-70MW). The S-band klystron and its modulator were combined to test their performance. The high power test results of the S-band klystron are summarized in this paper. (author)

Pulsed power accelerators for particle beam fusion

International Nuclear Information System (INIS)

Martin, T.H.; Barr, G.W.; VanDevender, J.P.; White, R.A.; Johnson, D.L.

1980-01-01

Sandia National Laboratories is completing the construction phase of the Particle Beam Fusion Accelerator-I (PBFA-I). Testing of the 36 module, 30 TW, 1 MJ output accelerator is in the initial stages. The 4 MJ, PBFA Marx generator has provided 3.6 MA into water-copper sulfate load resistors with a spread from first to last Marx firing between 15 to 25 ns and an output power of 5.7 TW. This accelerator is a modular, lower voltage, pulsed power device that is capable of scaling to power levels exceeding 100 TW. The elements of the PBFA technology and their integration into an accelerator system for particle beam fusion will be discussed

Status of the NASA Micro Pulse Lidar Network (MPLNET): overview of the network and future plans, new version 3 data products, and the polarized MPL

Science.gov (United States)

Welton, Ellsworth J.; Stewart, Sebastian A.; Lewis, Jasper R.; Belcher, Larry R.; Campbell, James R.; Lolli, Simone

2018-04-01

The NASA Micro Pulse Lidar Network (MPLNET) is a global federated network of Micro-Pulse Lidars (MPL) co-located with the NASA Aerosol Robotic Network (AERONET). MPLNET began in 2000, and there are currently 17 long-term sites, numerous field campaigns, and more planned sites on the way. We have developed a new Version 3 processing system including the deployment of polarized MPLs across the network. Here we provide an overview of Version 3, the polarized MPL, and current and future plans.

Frontiers in pulse-power-based high energy density plasma physics and its applications

International Nuclear Information System (INIS)

Horioka, Kazuhiko

2008-03-01

The papers in this volume of report were presented at the Symposium on Frontiers in Pulse-power-based High Energy Density Physics' held by National Institute for Fusion Science. The topics include the present status of high energy density plasma researches, extreme ultraviolet sources, intense radiation sources, high power ion beams, and R and D of related pulse power technologies. The 13 of the presented papers are indexed individually. (J.P.N.)

The Design of Nanosecond Fast-switch Pulsed High Voltage Power Supply Based on Solid-state

International Nuclear Information System (INIS)

Chen Wenguang; Chen Wei; Rao Yihua

2009-01-01

The high voltage pulsed power supply is applied in the experiment of the nuclear science widely. It main consist of DC high-voltage power supply (HVPS) and pulse modulator. The high-frequency series-resonant inverter technology and IGBT series technology are used to design the HVPS and the modulator, respectively. The main circuit, control circuit, high voltage transformer and solid-state switch are illuminated in the paper. The apparatus can operate at a maximum output voltage of 6 kilovolt, which can be modulated single pulse and also be modulated by series pulse. A prototype is fabricated and tested, experimental results show that the pulsed power supply is well-designed and rising edge time to meet the nsclass; it can achieve the requirement of rapid modulation. (authors)

A new digital pulse power supply in heavy ion research facility in Lanzhou

Science.gov (United States)

Wang, Rongkun; Chen, Youxin; Huang, Yuzhen; Gao, Daqing; Zhou, Zhongzu; Yan, Huaihai; Zhao, Jiang; Shi, Chunfeng; Wu, Fengjun; Yan, Hongbin; Xia, Jiawen; Yuan, Youjin

2013-11-01

To meet the increasing requirements of the Heavy Ion Research Facility in Lanzhou-Cooler Storage Ring (HIRFL-CSR), a new digital pulse power supply, which employs multi-level converter, was designed. This power supply was applied with a multi H-bridge converters series-parallel connection topology. A new control model named digital power supply regulator system (DPSRS) was proposed, and a pulse power supply prototype based on DPSRS has been built and tested. The experimental results indicate that tracking error and ripple current meet the requirements of this design. The achievement of prototype provides a perfect model for HIRFL-CSR power supply system.

High-Wattage Pulsed Irradiation of Linearly Polarized Near-Infrared Light to Stellate Ganglion Area for Burning Mouth Syndrome

Directory of Open Access Journals (Sweden)

Yukihiro Momota

2014-01-01

Full Text Available The purpose of this study was to apply high-wattage pulsed irradiation of linearly polarized near-infrared light to the stellate ganglion area for burning mouth syndrome (BMS and to assess the efficacy of the stellate ganglion area irradiation (SGR on BMS using differential time-/frequency-domain parameters (D parameters. Three patients with BMS received high-wattage pulsed SGR; the response to SGR was evaluated by visual analogue scale (VAS representing the intensity of glossalgia and D parameters used in heart rate variability analysis. High-wattage pulsed SGR significantly decreased the mean value of VAS in all cases without any adverse event such as thermal injury. D parameters mostly correlated with clinical condition of BMS. High-wattage pulsed SGR was safe and effective for the treatment of BMS; D parameters are useful for assessing efficacy of SGR on BMS.

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

International Nuclear Information System (INIS)

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

2011-01-01

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 01 -TE 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 μs) 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 μs 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 that two of

Fundamental study on metal plating removal using pulsed power technology

International Nuclear Information System (INIS)

Imasaka, Kiminobu; Gnapowski, Sebastian; Akiyama, Hidenori

2013-01-01

A novel method for the metal removal from metal-plated substrate using pulsed power technology is proposed. A metal-plated substrate with three metal-layers structure (Cu, Ni and Au) is used as the sample substrate. Repetitive pulsed arc discharge plasma is generated between a rod electrode and the surface of substrate. Effect of the type of electrode system on metal plating removal was investigated. The removal region is produced by the moving phenomena of the pulsed arc discharge. A part of Au layer, which is the tompost metal surface of the substrate is vaporized and removed by the repetitive pulsed arc discharges. The proposed method can be used for recycle of metal-plated substrate. (author)

Extended Pulse-Powered Humidity-Freeze Cycling for Testing Module-Level Power Electronics

Energy Technology Data Exchange (ETDEWEB)

Hacke, Peter L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Rodriguez, Miguel [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kempe, Michael D [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Repins, Ingrid L [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2017-11-28

An EMI suppression capacitor (polypropylene film type) failed by 'popcorning' due to vapor outgassing in pulse powered humidity-freeze cycles. No shorts or shunts could be detected despite mildly corroded metallization visible in the failed capacitor. Humidity-freeze cycling is optimized to break into moisture barriers. However, further studies will be required on additional module level power electronic (MLPE) devices to optimize the stress testing for condensation to precipitate any weakness to short circuiting and other humidity/bias failure modes.

Investigations on the relationship between power spectrum and signal-to-noise ratio of frequency-swept pulses

International Nuclear Information System (INIS)

Zhang Zhuhong; Fan Diayuan

1993-01-01

The criterion for obtaining compressed chirp pulses with high signal-to-noise ratio is the shape of the power spectrum, a chirp pulse of Gaussian shaped power spectrum without modulation is needed in CPA system to get the clean compressed pulses. 4 refs., 2 figs

Exponential power spectra, deterministic chaos and Lorentzian pulses in plasma edge dynamics

International Nuclear Information System (INIS)

Maggs, J E; Morales, G J

2012-01-01

Exponential spectra have been observed in the edges of tokamaks, stellarators, helical devices and linear machines. The observation of exponential power spectra is significant because such a spectral character has been closely associated with the phenomenon of deterministic chaos by the nonlinear dynamics community. The proximate cause of exponential power spectra in both magnetized plasma edges and nonlinear dynamics models is the occurrence of Lorentzian pulses in the time signals of fluctuations. Lorentzian pulses are produced by chaotic behavior in the separatrix regions of plasma E × B flow fields or the limit cycle regions of nonlinear models. Chaotic advection, driven by the potential fields of drift waves in plasmas, results in transport. The observation of exponential power spectra and Lorentzian pulses suggests that fluctuations and transport at the edge of magnetized plasmas arise from deterministic, rather than stochastic, dynamics. (paper)

New Pulsed Power Technology for High Current Accelerators

International Nuclear Information System (INIS)

Caporaso, G J

2002-01-01

Recent advances in solid-state modulators now permit the design of a new class of high current accelerators. These new accelerators will be able to operate in burst mode at frequencies of several MHz with unprecedented flexibility and precision in pulse format. These new modulators can drive accelerators to high average powers that far exceed those of any other technology and can be used to enable precision beam manipulations. New insulator technology combined with novel pulse forming lines and switching may enable the construction of a new type of high gradient, high current accelerator. Recent developments in these areas will be reviewed

Pen harvester for powering a pulse rate sensor

International Nuclear Information System (INIS)

Bedekar, Vishwas; Oliver, Josiah; Priya, Shashank

2009-01-01

Rapid developments in the area of micro-sensors for various applications such as structural health monitoring, bio-chemical sensors and pressure sensors have increased the demand for portable, low cost, high efficiency energy harvesting devices. In this paper, we describe the scheme for powering a pulse rate sensor with a vibration energy harvester integrated inside a pen commonly carried by humans in the pocket close to the heart. Electromagnetic energy harvesting was selected in order to achieve high power at lower frequencies. The prototype pen harvester was found to generate 3 mW at 5 Hz and 1 mW at 3.5 Hz operating under displacement amplitude of 16 mm (corresponding to an acceleration of approximately 1.14 g rms at 5 Hz and 0.56 g rms at 3.5 Hz, respectively). A comprehensive mathematical modelling and simulations were performed in order to optimize the performance of the vibration energy harvester. The integrated pen harvester prototype was found to generate continuous power of 0.46-0.66 mW under normal human actions such as jogging and jumping which is enough for a small scale pulse rate sensor.

Application of pulse power technology to ultra high energy electron accelerators

International Nuclear Information System (INIS)

Nation, J.A.

1989-01-01

The author presents in this paper a review of the application of pulse power technology to the development of high gradient electron accelerators. The technology demands are relatively modest compared to the ultra high power technology used for inertial confinement fusion drivers. With the advent of magnetic switching intense electron beams can be generated with a sufficiently high repetition rate to be of interest for high energy electron accelerator driver applications. Most of the techniques considered rely on the excitation of large amplitude waves on the beams. Within this framework there are two broad categories of accelerator, those in which the waves are directly excited in and supported by the medium and, secondly, those where the waves are used to generate radiofrequency signals which are then coupled via structures to the beam being accelerated. In what follows we shall consider both approaches. Present-day pulse power technology limits pulse durations to about 100 nsec. Consequently, if these sources are to be used, we will need to use high group velocity structures to avoid the need for short accelerator module lengths. An advantage of the short pulse duration is that the available acceleration voltage gradient increases compared to that obtained using conventional rf drivers. 19 references, 9 figures, 1 table

Status of the NASA Micro Pulse Lidar Network (MPLNET: overview of the network and future plans, new version 3 data products, and the polarized MPL

Directory of Open Access Journals (Sweden)

Welton Ellsworth J.

2018-01-01

Full Text Available The NASA Micro Pulse Lidar Network (MPLNET is a global federated network of Micro-Pulse Lidars (MPL co-located with the NASA Aerosol Robotic Network (AERONET. MPLNET began in 2000, and there are currently 17 long-term sites, numerous field campaigns, and more planned sites on the way. We have developed a new Version 3 processing system including the deployment of polarized MPLs across the network. Here we provide an overview of Version 3, the polarized MPL, and current and future plans.

Electromagnetic pulse research on electric power systems: Program summary and recommendations. Power Systems Technology Program

Energy Technology Data Exchange (ETDEWEB)

Barnes, P.R.; McConnell, B.W.; Van Dyke, J.W. [Oak Ridge National Lab., TN (United States); Tesche, F.M. [Tesche (F.M.), Dallas, TX (United States); Vance, E.F. [Vance (E.F.), Fort Worth, TX (United States)

1993-01-01

A single nuclear detonation several hundred kilometers above the central United States will subject much of the nation to a high-altitude electromagnetic pulse (BENT). This pulse consists of an intense steep-front, short-duration transient electromagnetic field, followed by a geomagnetic disturbance with tens of seconds duration. This latter environment is referred to as the magnetohydrodynamic electromagnetic pulse (NMENT). Both the early-time transient and the geomagnetic disturbance could impact the operation of the nation`s power systems. Since 1983, the US Department of Energy has been actively pursuing a research program to assess the potential impacts of one or more BENT events on the nation`s electric energy supply. This report summarizes the results of that program and provides recommendations for enhancing power system reliability under HENT conditions. A nominal HENP environment suitable for assessing geographically large systems was developed during the program and is briefly described in this report. This environment was used to provide a realistic indication of BEMP impacts on electric power systems. It was found that a single high-altitude burst, which could significantly disturb the geomagnetic field, may cause the interconnected power network to break up into utility islands with massive power failures in some areas. However, permanent damage would be isolated, and restoration should be possible within a few hours. Multiple bursts would likely increase the blackout areas, component failures, and restoration time. However, a long-term blackout of many months is unlikely because major power system components, such as transformers, are not likely to be damaged by the nominal HEND environment. Moreover, power system reliability, under both HENT and normal operating conditions, can be enhanced by simple, and often low cost, modifications to current utility practices.

Laser accelerated protons captured and transported by a pulse power solenoid

Directory of Open Access Journals (Sweden)

T. Burris-Mog

2011-12-01

Full Text Available Using a pulse power solenoid, we demonstrate efficient capture of laser accelerated proton beams and the ability to control their large divergence angles and broad energy range. Simulations using measured data for the input parameters give inference into the phase-space and transport efficiencies of the captured proton beams. We conclude with results from a feasibility study of a pulse power compact achromatic gantry concept. Using a scaled target normal sheath acceleration spectrum, we present simulation results of the available spectrum after transport through the gantry.

Optimization of IGCT for pulsed power

International Nuclear Information System (INIS)

Chen Fanglin; Tang Longgu; Chen Yongmin; Pan Xuejun

2014-01-01

In order to develop high-performance IGCT devices applied in pulse power, cathode finger layout is optimized, the finger structure is modified, minority carrier lifetime is properly controlled and gate triggering characteristics is improved. As a result of these measures, the IGCT turn -on di/dt is improved, current handling capability is enhanced and switching response speed is increased. The feasibility and validity of the optimization study on the IGCT is verified by simulation and experimental results. (authors)

Pulse Power--A Heart Physiology Program for Children.

Science.gov (United States)

Hinson, Curt

1994-01-01

Primary grade students at a Delaware elementary school currently participate in the Pulse Power heart physiology program. Students receive mastery instruction and use heart monitors to exercise performance throughout the 6-phase program. Data from homework and from the heart monitors identify student progress, knowledge, and cardiovascular…

Controllable pulse parameter transcranial magnetic stimulator with enhanced circuit topology and pulse shaping

Science.gov (United States)

Peterchev, Angel V.; DʼOstilio, Kevin; Rothwell, John C.; Murphy, David L.

2014-10-01

Objective. This work aims at flexible and practical pulse parameter control in transcranial magnetic stimulation (TMS), which is currently very limited in commercial devices. Approach. We present a third generation controllable pulse parameter device (cTMS3) that uses a novel circuit topology with two energy-storage capacitors. It incorporates several implementation and functionality advantages over conventional TMS devices and other devices with advanced pulse shape control. cTMS3 generates lower internal voltage differences and is implemented with transistors with a lower voltage rating than prior cTMS devices. Main results. cTMS3 provides more flexible pulse shaping since the circuit topology allows four coil-voltage levels during a pulse, including approximately zero voltage. The near-zero coil voltage enables snubbing of the ringing at the end of the pulse without the need for a separate active snubber circuit. cTMS3 can generate powerful rapid pulse sequences (\\lt 10 ms inter pulse interval) by increasing the width of each subsequent pulse and utilizing the large capacitor energy storage, allowing the implementation of paradigms such as paired-pulse and quadripulse TMS with a single pulse generation circuit. cTMS3 can also generate theta (50 Hz) burst stimulation with predominantly unidirectional electric field pulses. The cTMS3 device functionality and output strength are illustrated with electrical output measurements as well as a study of the effect of pulse width and polarity on the active motor threshold in ten healthy volunteers. Significance. The cTMS3 features could extend the utility of TMS as a research, diagnostic, and therapeutic tool.

Pulsed power experiments in hydrodynamics and material properties

CERN Document Server

Reinovsky, R E

1999-01-01

A new application for high performance pulsed power program, the production of high energy density environments in materials for the study of material properties and hydrodynamics in complex geometries, has joined family of radiation source applications in the Stockpile Stewardship. The principle tool for producing high energy density environments is the high precision, magnetically imploded, near-solid density liner. The most attractive pulsed power system for driving such experiments is an ultra-high current, low impedance, microsecond time scale source that is economical both to build and operate. The 25-MJ Atlas capacitor bank system currently under construction at Los Alamos is the first system of its scale specifically designed to drive high precision solid liners. Delivering 30 MA, Atlas will provide liner velocities 12-15 km/sec and kinetic energies of 1-2 MJ /cm with extensive diagnostics and excellent reproducibility. Explosive flux compressor technology provides access to currents exceeding 100 MA ...

3.5 MeV pulsed power system for LIA injector

International Nuclear Information System (INIS)

Li Jin; Dai Guangsen; Liu Xiaoping; Zhang Kaizhi; Li Xin; Li Yuan; Xia Liansheng; Xie Min; Zhang Linwen; Deng Jianjun; Ding Bonan

2005-01-01

A 3.5 MeV injector for linear induction accelerator has been built up at Institute of Fluid Physics, China Academy of Engineering Physics. The injector is based on the principle of inductive adder. It consists of 12 induction cells. Seven induction cells are on the cathode stem side, which are connected in series, and provide about 2 MV on the cathode of the diode. The other five are connected in series on the anode stem side and provide about 1.5 MV on the anode of the diode. A 3.5 MV pulsed power system to provide energy for the injector has been designed, which consists of two Marx generators, 12 water insulated Blumleins, and trigger system. Charge voltage of each water insulated Blumlein is 200 kV. A 300 kV/90 ns high voltage pulse is fed into one induction cell since load impedance is higher. The pulsed power system can generate an intense electron beam with 2-3 kA. (authors)

Frontiers of particle beam and high energy density plasma science using pulse power technology

International Nuclear Information System (INIS)

Masugata, Katsumi

2011-04-01

The papers presented at the symposium on “Frontiers of Particle Beam and High Energy Density Plasma Science using Pulse Power Technology” held in November 20-21, 2009 at National Institute for Fusion Science are collected. The papers reflect the present status and resent progress in the experiment and theoretical works on high power particle beams and high energy density plasmas produced by pulsed power technology. (author)

Performance and reliability of TPE-2 device with pulsed high power source

International Nuclear Information System (INIS)

Sato, Y.; Takeda, S.; Kiyama, S.

1987-01-01

The performance and the reliability of TPE-2 device with pulsed high power sources are described. To obtain the stable high beta plasma, the reproducibility and the reliability of the pulsed power sources must be maintained. A new power crowbar system with high efficiency and the switches with low jitter time are adopted to the bank system. A monitor system which always watches the operational states of the switches is developed too, and applied for the fast rising capacitor banks of TPE-2 device. The reliable operation for the bank has been realized, based on the data of switch monitor system

Conductive graphene as passive saturable absorber with high instantaneous peak power and pulse energy in Q-switched regime

Science.gov (United States)

Zuikafly, Siti Nur Fatin; Khalifa, Ali; Ahmad, Fauzan; Shafie, Suhaidi; Harun, SulaimanWadi

2018-06-01

The Q-switched pulse regime is demonstrated by integrating conductive graphene as passive saturable absorber producing relatively high instantaneous peak power and pulse energy. The fabricated conductive graphene is investigated using Raman spectroscopy. The single wavelength Q-switching operates at 1558.28 nm at maximum input pump power of 151.47 mW. As the pump power is increased from threshold power of 51.6 mW to 151.47 mW, the pulse train repetition rate increases proportionally from 47.94 kHz to 67.8 kHz while the pulse width is reduced from 9.58 μs to 6.02 μs. The generated stable pulse produced maximum peak power and pulse energy of 32 mW and 206 nJ, respectively. The first beat node of the measured signal-to-noise ratio is about 62 dB indicating high pulse stability.

High-Average-Power Diffraction Pulse-Compression Gratings Enabling Next-Generation Ultrafast Laser Systems

Energy Technology Data Exchange (ETDEWEB)

Alessi, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-11-01

Pulse compressors for ultrafast lasers have been identified as a technology gap in the push towards high peak power systems with high average powers for industrial and scientific applications. Gratings for ultrashort (sub-150fs) pulse compressors are metallic and can absorb a significant percentage of laser energy resulting in up to 40% loss as well as thermal issues which degrade on-target performance. We have developed a next generation gold grating technology which we have scaled to the petawatt-size. This resulted in improvements in efficiency, uniformity and processing as compared to previous substrate etched gratings for high average power. This new design has a deposited dielectric material for the grating ridge rather than etching directly into the glass substrate. It has been observed that average powers as low as 1W in a compressor can cause distortions in the on-target beam. We have developed and tested a method of actively cooling diffraction gratings which, in the case of gold gratings, can support a petawatt peak power laser with up to 600W average power. We demonstrated thermo-mechanical modeling of a grating in its use environment and benchmarked with experimental measurement. Multilayer dielectric (MLD) gratings are not yet used for these high peak power, ultrashort pulse durations due to their design challenges. We have designed and fabricated broad bandwidth, low dispersion MLD gratings suitable for delivering 30 fs pulses at high average power. This new grating design requires the use of a novel Out Of Plane (OOP) compressor, which we have modeled, designed, built and tested. This prototype compressor yielded a transmission of 90% for a pulse with 45 nm bandwidth, and free of spatial and angular chirp. In order to evaluate gratings and compressors built in this project we have commissioned a joule-class ultrafast Ti:Sapphire laser system. Combining the grating cooling and MLD technologies developed here could enable petawatt laser systems to

A proposal to pulse the Bevatron/Bevalac main guide field magnet with SCR power supplies

International Nuclear Information System (INIS)

Frias, B.; Alonso, J.; Dwinell, R.; Lothrop, F.

1989-01-01

The Bevatron/Bevalac Main Guide Field Power Supply was originally designed to provide a 15,250 Volt DC. at sign 8400 Ampere peak magnet pulse. Protons were accelerated to 6.2 Gev. The 128 Megawatt (MW) pulse required two large motor-generator (MG) sets with 67 ton flywheels to store 680 Megajoules of energy. Ignitron rectifiers are used to rectify the generator outputs. Acceleration of heavy ions results in an operating schedule with a broad range of peak fields. The maximum field of 12.5 kilogauss requires a peak pulse of 80 MW. Acceleration of ions to 1.0 kilogauss requires an 8 MW peak pulse. One MG set can provide pulses below 45 MW. Peak pulses of less than 15 MW are now a large block of the operating schedule. A proposal has been made to replace the existing MG system with eight SCR power supplies for low field operation. The SCR supplies will be powered directly from the Lawrence Berkeley Laboratory's 12.3 KV. power distribution system. This paper describes the many advantages of the plan. 4 refs., 3 figs., 3 tabs

Low-loss polarization-maintaining fusion splicing of single-mode fibers and hollow-core photonic crystal fibers, relevant for monolithic fiber laser pulse compression

DEFF Research Database (Denmark)

Kristensen, Jesper Toft; Houmann, Andreas; Liu, Xiaomin

2008-01-01

of the splicing process. We also demonstrate that the higher splice loss compromises the PM properties of the splice. Our splicing technique was successfully applied to the realization of a low-loss, environmentally stable monolithic PM fiber laser pulse compressor, enabling direct end-of-the-fiber femtosecond......We report on highly reproducible low-loss fusion splicing of polarization-maintaining single-mode fibers (PM-SMFs) and hollow-core photonic crystal fibers (HC-PCFs). The PM-SMF-to-HC-PCF splices are characterized by the loss of 0.62 ± 0.24 dB, and polarization extinction ratio of 19 ± 0.68 d...... pulse delivery...

Power systems for the Doublet III 2-MW ECH system

International Nuclear Information System (INIS)

Remsen, D.B. Jr.

1981-10-01

A system providing 5 second pulses at 60 GHz from ten 200 kW gyrotrons is being prepared for electron cyclotron heating experiments on Doublet III. The power supply for the gyrotron system is a power supply currently under construction by Universal Voltronics Corporation for the Doublet III neutral beam power supply, and is to have the option of reverse polarity (negative) to fill the needs of the system of ten gyrotons operating in parallel. The output of this power supply is 80 kV at 100A for 5 second pulses with good regulation. The output pulse rise and fall times and fault protection response time are all compatible with the gyrotron requirements

Power dependent filamentation of a femtosecond laser pulse in air by focusing with an axicon

International Nuclear Information System (INIS)

Sun, Xiaodong; Zeng, Tao; Liu, Weiwei; Gao, Hui; Zhang, Siwen

2015-01-01

In the present work, femtosecond laser filament generation by focusing the laser pulse with an axicon in air is studied at different input laser powers both experimentally and numerically. It is found that the length of the filament increases almost linearly with the input laser power. Moreover, the laser intensity inside the filament starts to saturate at a power much higher than the critical power of self-focusing for a Gaussian beam. We have also observed the laser pulse self-compression during nonlinear propagation. The shortest pulse duration could be obtained at the center of the effective focal region produced by the axicon. (paper)

Circuit designs for measuring reactor period, peak power, and pulse fluence on TRIGA and other pulse reactor

International Nuclear Information System (INIS)

Meyer, R.D.; Thome, F.V.; Williams, R.L.

1976-01-01

Inexpensive circuits for use in evaluating reactor pulse prompt period, peak power, and pulse fluence (NVT) are presented. In addition to low cost, these circuits are easily assembled and calibrated and operate with a high degree of accuracy. The positive period measuring system has been used in evaluating reactivity additions as small as 5 cents (with an accuracy of ±0.1 cents) and as large as $4.50 (accuracy ±2 cents). Reactor peak power is measured digitally with a system accuracy of ±0.04% of a 10 Volt input (±4 mV). The NVT circuit measures over a 2-1/2 decade range, has 3 place resolution and an accuracy of better than 1%. (author)

Design and development of a high-power, 500 kV pulsed line

International Nuclear Information System (INIS)

Nicolas, A.

A study was made of very high voltage (500 kV) pulse production for 50 ns at half height. A coaxial line was coupled to a Marx generator for obtaining the pulses on an impedance-adapted electron diode. The maximum power obtained was 6.4 x 10 10 W with a current front in the diode of about 30 ns (80 ns pulse length at half height)

Influence of dispersion stretching of ultrashort UV laser pulse on the critical power for self-focusing

Science.gov (United States)

Ionin, A. A.; Mokrousova, D. V.; Piterimov, D. A.; Seleznev, L. V.; Sinitsyn, D. V.; Sunchugasheva, E. S.

2018-04-01

The critical power for self-focusing in air for ultrashort ultraviolet laser pulses, stretched due to dispersion from 90 to 730 fs, was experimentally measured. It was shown that the pulse duration enhancement due to its propagation in condensed media leads to an almost linear decrease in the critical power for self-focusing. It was also observed that when the pulse peak power exceeds the critical one, the maximum of linear plasma distribution along the ultraviolet laser filament does not shift in the direction opposite to the laser pulse propagation, as observed for infrared laser filaments, but remains at the geometrical focus.

Comparison of power pulses from homogeneous and time-average-equivalent models

International Nuclear Information System (INIS)

De, T.K.; Rouben, B.

1995-01-01

The time-average-equivalent model is an 'instantaneous' core model designed to reproduce the same three dimensional power distribution as that generated by a time-average model. However it has been found that the time-average-equivalent model gives a full-core static void reactivity about 8% smaller than the time-average or homogeneous models. To investigate the consequences of this difference in static void reactivity in time dependent calculations, simulations of the power pulse following a hypothetical large-loss-of-coolant accident were performed with a homogeneous model and compared with the power pulse from the time-average-equivalent model. The results show that there is a much smaller difference in peak dynamic reactivity than in static void reactivity between the two models. This is attributed to the fact that voiding is not complete, but also to the retardation effect of the delayed-neutron precursors on the dynamic flux shape. The difference in peak reactivity between the models is 0.06 milli-k. The power pulses are essentially the same in the two models, because the delayed-neutron fraction in the time-average-equivalent model is lower than in the homogeneous model, which compensates for the lower void reactivity in the time-average-equivalent model. (author). 1 ref., 5 tabs., 9 figs

Design and testing of 45 kV, 50 kHz pulse power supply for dielectric barrier discharges

Science.gov (United States)

Sharma, Surender Kumar; Shyam, Anurag

2016-10-01

The design, construction, and testing of high frequency, high voltage pulse power supply are reported. The purpose of the power supply is to generate dielectric barrier discharges for industrial applications. The power supply is compact and has the advantage of low cost, over current protection, and convenient control for voltage and frequency selection. The power supply can generate high voltage pulses of up to 45 kV at the repetitive frequency range of 1 kHz-50 kHz with 1.2 kW input power. The output current of the power supply is limited to 500 mA. The pulse rise time and fall time are less than 2 μs and the pulse width is 2 μs. The power supply is short circuit proof and can withstand variable plasma load conditions. The power supply mainly consists of a half bridge series resonant converter to charge an intermediate capacitor, which discharges through a step-up transformer at high frequency to generate high voltage pulses. Semiconductor switches and amorphous cores are used for power modulation at higher frequencies. The power supply is tested with quartz tube dielectric barrier discharge load and worked stably. The design details and the performance of the power supply on no load and dielectric barrier discharge load are presented.

Built and operation of three powerful AC pulse flywheel generator sets

International Nuclear Information System (INIS)

Wang Shujin; Li Huajun; Li Zhijian; Huang Zhaorong; Wang Xiaoping; Xu Lirong; Liu Xuemei; Bu Mingnan; Hu Haotian; Mao Weicheng

2006-10-01

Based on modification of the old pulse generator sets the new flywheel generator system has been developed. Now it is successfully used in supplying power to the HL-2A tokamak and meets the needs of HL-2A physical experiments. By far it is the most powerful pulse flywheel generator system on in-stalled gross capacity, energy storage and release in China today. In addition, the characteristic of the flywheel generator system is that each generator stator has two Y windings with 30 degree phase shift to avoid damaging the rotor due to rectifying load. (authors)

Giant Pulse Phenomena in a High Gain Erbium Doped Fiber Amplifier

Science.gov (United States)

Li, Stephen X.; Merritt, Scott; Krainak, Michael A.; Yu, Anthony

2018-01-01

High gain Erbium Doped Fiber Amplifiers (EDFAs) are vulnerable to optical damage when unseeded, e.g. due to nonlinear effects that produce random, spontaneous Q-switched (SQS) pulses with high peak power, i.e. giant pulses. Giant pulses can damage either the components within a high gain EDFA or external components and systems coupled to the EDFA. We explore the conditions under which a reflective, polarization-maintaining (PM), core-pumped high gain EDFA generates giant pulses, provide details on the evolution of normal pulses into giant pulses, and provide results on the transient effects of giant pulses on an amplifier's fused-fiber couplers, an effect which we call Fiber Overload Induced Leakage (FOIL). While FOIL's effect on fused-fiber couplers is temporary, its damage to forward pump lasers in a high gain EDFA can be permanent.

Motion of the dayside polar cap boundary during substorm cycles: II. Generation of poleward-moving events and polar cap patches by pulses in the magnetopause reconnection rate

Directory of Open Access Journals (Sweden)

M. Lockwood

2005-12-01

Full Text Available Using data from the EISCAT (European Incoherent Scatter VHF and CUTLASS (Co-operative UK Twin-Located Auroral Sounding System HF radars, we study the formation of ionospheric polar cap patches and their relationship to the magnetopause reconnection pulses identified in the companion paper by Lockwood et al. (2005. It is shown that the poleward-moving, high-concentration plasma patches observed in the ionosphere by EISCAT on 23 November 1999, as reported by Davies et al. (2002, were often associated with corresponding reconnection rate pulses. However, not all such pulses generated a patch and only within a limited MLT range (11:00-12:00 MLT did a patch result from a reconnection pulse. Three proposed mechanisms for the production of patches, and of the concentration minima that separate them, are analysed and evaluated: (1 concentration enhancement within the patches by cusp/cleft precipitation; (2 plasma depletion in the minima between the patches by fast plasma flows; and (3 intermittent injection of photoionisation-enhanced plasma into the polar cap. We devise a test to distinguish between the effects of these mechanisms. Some of the events repeat too frequently to apply the test. Others have sufficiently long repeat periods and mechanism (3 is shown to be the only explanation of three of the longer-lived patches seen on this day. However, effect (2 also appears to contribute to some events. We conclude that plasma concentration gradients on the edges of the larger patches arise mainly from local time variations in the subauroral plasma, via the mechanism proposed by Lockwood et al. (2000.

Optical reconfiguration and polarization control in semi-continuous gold films close to the percolation threshold

DEFF Research Database (Denmark)

Frydendahl, Christian; Repän, Taavi; Geisler, Mathias

2017-01-01

permanent morphological changes with a femtosecond (fs)-pulsed laser above a critical power. Optical transmission spectroscopy measurements show a correlation between the spectra of the morphologically modified films and the wavelength, polarization, and the intensity of the laser used for alteration...

Applications of pulsed power in advanced oxidation and reduction processes for pollution control

International Nuclear Information System (INIS)

Rosocha, L.A.; Coogan, J.J.; Secker, D.A.; Smith, J.D.

1993-01-01

A growing social awareness of the adverse impact of pollutants on our environment and the promulgation of environmental laws and regulations has recently stimulated the development of technologies for pollution abatement and hazardous waste destruction. Pulsed power shows strong promise for contributing to the development of innovative technologies aimed at these applications. At Los Alamos we are engaged in two projects which apply pulsed power technology to the environment: the use of relativistic electron beams and nonequilibrium plasmas for the destruction of hazardous organic compounds in aqueous-based and gaseous-based medial, respectively. Electron beams and nonequilibrium plasmas have also been applied to the treatment of flue gases such as SO x and NO x by other researchers. In this paper, we will describe our electron-beam and plasma experiments carried out on hazardous waste destruction. Additionally, we will describe the scaling of electron-beam and nonequilibrium plasma systems to industrial sizes, including discussions of electron accelerator architecture, comparison of continuous-duty versus repetitively pulsed accelerators, plasma-discharge modulators, and needed pulsed power technology development

Numerical study of the propagation of high power microwave pulses in air breakdown environment

International Nuclear Information System (INIS)

Kim, J.; Kuo, S.P.

1992-01-01

A theoretical model based on a set of two modal equations has been developed to describe self-consistently the propagation of an intense microwave pulse in an air breakdown environment. It includes Poynting's equation for the continuity of the power flux of the pulse and the rate equation of the electron density. A forward wave approximation is used to simplify Poynting's equation and a semi-empirical formula for the ionization frequency as a function of the wave field amplitude is adopted for this model. In order to improve the numerical efficiency of the model in terms of the required computation time and available subroutines for numerical analysis of pulse propagation over a long distance, a transformation to the frame of local time of the pulse is introduced. The effect of space-time dependence of the group velocity of the pulse is included in this properly designed transformation. The inhomogeneous feature of the background pressure is also preserved in the model. The resultant equations are reduced to the forms which can be solved directly by the available subroutine of ODE solver. In this work, a comprehensive numerical analysis of the propagation of high power microwave pulse through the atmosphere is performed. It is shown that the pulse energy can severely be attenuated by the self-generated plasma. Therefore, the aim of the present study is to identify the optimum parameters of the pulse so that the energy loss of the pulse before reaching the destination can be minimized. These parameters include the power, frequency, shape and length of the pulse. The conditions for maximizing the ionization at a destinated region in the upper atmosphere will also be determined

Broadband and short (10-ps) pulse generation on Nova

International Nuclear Information System (INIS)

Perry, M.D.; Browning, D.; Bibeau, C.; Patterson, F.G.; Wilcox, R.; Henesian, M.

1990-01-01

The ability to produce high power broadband pulses for purposes of focal spot beam smoothing has recently become an important issue in inertial confinement fusion (ICF). As the first step toward the generation and propagation of such pulses on Nova, the authors have performed a series of experiments with 10-ps pulses. Aside from the inherently broad bandwidth, these short pulses have important applications in ICF experiments and x-ray laser research. The author's experimental results are discussed. The short pulses were produced by diffraction grating pulse compression of chirped pulses formed from self-phase modulation in a single-mode 10-m fused silica fiber. Use of such a short fiber produces a nonlinearly chirped spectrum of 0.74 nm. The central nearly linearly chirped 0.26 nm is selected by polarization discrimination and compressed using 1800-line/mm diffraction gratings to a nearly Gaussian pulse of 10 ps FWHM with an energy contrast ratio of 20:1. This 1-nJ pulse is injected into a Nova amplifier chain with selected amplifiers unfired

Preliminary results of a battery-based, multi megawatt 200 kA pulsed power supply.

NARCIS (Netherlands)

Karthaus, W.; Kolkert, W.J.; Nowee, J.

1989-01-01

A pulsed power supply consisting of a fast discharge battery, a switch based on silicon-controlled-rectifier SCR technology, and an energy storage/pulse transformer is discussed. Preliminary results indicate that the battery is capable of discharging current pulses with reproducible peak values of

Ozone Synthesis Efficiency Upgrading in the Pulsed Point-to-Plane Gas Discharge

International Nuclear Information System (INIS)

Golota, V.I.; Zavada, L.M.; Kotyukov, O.V.; Polyakov, A.V.; Pugach, S.G.

2006-01-01

Results are reported from the studies into electrodynamic characteristics of the barrierless point-to-plane gas discharge as a HV pulse of positive polarity is applied to the point electrode. The efficiency of ozone synthesis has been determined as a function of the length and repetition frequency of the HV pulse. It has been demonstrated that the electrodynamic characteristics of the discharge and the efficiency of ozone synthesis in oxygen-containing gas mixtures essentially depend on the parameters of HV power supply. The HV switch HTS-300 (BEHLKE Electronic GmbH) was used for HV pulse shaping

Nine-channel mid-power bipolar pulse generator based on a field programmable gate array

Energy Technology Data Exchange (ETDEWEB)

Haylock, Ben, E-mail: benjamin.haylock2@griffithuni.edu.au; Lenzini, Francesco; Kasture, Sachin; Fisher, Paul; Lobino, Mirko [Centre for Quantum Dynamics, Griffith University, Brisbane (Australia); Queensland Micro and Nanotechnology Centre, Griffith University, Brisbane (Australia); Streed, Erik W. [Centre for Quantum Dynamics, Griffith University, Brisbane (Australia); Institute for Glycomics, Griffith University, Gold Coast (Australia)

2016-05-15

Many channel arbitrary pulse sequence generation is required for the electro-optic reconfiguration of optical waveguide networks in Lithium Niobate. Here we describe a scalable solution to the requirement for mid-power bipolar parallel outputs, based on pulse patterns generated by an externally clocked field programmable gate array. Positive and negative pulses can be generated at repetition rates up to 80 MHz with pulse width adjustable in increments of 1.6 ns across nine independent outputs. Each channel can provide 1.5 W of RF power and can be synchronised with the operation of other components in an optical network such as light sources and detectors through an external clock with adjustable delay.

Nearly fully compressed 1053 nm pulses directly obtained from 800 nm laser-seeded photonic crystal fiber below zero dispersion point

Science.gov (United States)

Refaeli, Zaharit; Shamir, Yariv; Ofir, Atara; Marcus, Gilad

2018-02-01

We report a simple robust and broadly spectral-adjustable source generating near fully compressed 1053 nm 62 fs pulses directly out of a highly-nonlinear photonic crystal fiber. A dispersion-nonlinearity balance of 800 nm Ti:Sa 20 fs pulses was obtained initially by negative pre-chirping and then launching the pulses into the fibers' normal dispersion regime. Following a self-phase modulation spectral broadening, some energy that leaked below the zero dispersion point formed a soliton whose central wavelength could be tuned by Self-Frequency-Raman-Shift effect. Contrary to a common approach of power, or, fiber-length control over the shift, here we continuously varied the state of polarization, exploiting the Raman and Kerr nonlinearities responsivity for state of polarization. We obtained soliton pulses with central wavelength tuned over 150 nm, spanning from well below 1000 to over 1150 nm, of which we could select stable pulses around the 1 μm vicinity. With linewidth of > 20 nm FWHM Gaussian-like temporal-shape pulses with 62 fs duration and near flat phase structure we confirmed high quality pulse source. We believe such scheme can be used for high energy or high power glass lasers systems, such as Nd or Yb ion-doped amplifiers and systems.

The effects of lightning and high altitude electromagnetic pulse on power distribution lines

Energy Technology Data Exchange (ETDEWEB)

Uman, M.A.; Rubinstein, M.; Yacoub, Z. [Florida Univ., Gainesville, FL (United States)

1995-01-01

We simultaneously recorded the voltages induced by lightning on both ends of an unenergized 448-meter long unenergized electric power line and the lightning vertical electric and horizontal magnetic fields at ground level near the line. The lightning data studied and presented here were due both to cloud lightning and to very close (about 20 m from the line) artificially initiated lightning. For cloud sources, a frequency-domain computer program called EMPLIN was used to calculate induced line voltages as a function of source elevation, angle of incidence, and wave polarization of the radiated cloud discharge pulses in order to compare with the measurements. For very-close lightning, the measured line voltages could be grouped into two categories, those in which multiple, similarly shaped, evenly spaced pulses were observed, which we call oscillatory, and those dominated by a principal pulse with subsidiary oscillations of much smaller amplitude, which we call impulsive. The amplitude of the induced voltage ranged from tens of kilovolts for oscillatory voltages to hundreds of kilovolts for impulsive voltages. A new technique is derived for the calculation of the electromagnetic fields from nearby lightning to ground above an imperfectly conducting ground. This technique was used in conjunction with an existing time domain coupling theory and lightning return stroke model to calculate voltages at either end of the line. The results show fair agreement with the measured oscillatory voltage waveforms if corona is ignored and improved results when corona effects are modeled. The modeling of the impulsive voltage, for which local flashover probably successful. In an attempt to understand better the sources of the line voltages for very close lightning, measurements of the horizontal and vertical electric fields 30 m from triggered lightning were obtained.

High power pulsed sources based on fiber amplifiers

Science.gov (United States)

Canat, Guillaume; Jaouën, Yves; Mollier, Jean-Claude; Bouzinac, Jean-Pierre; Cariou, Jean-Pierre

2017-11-01

Cladding-pumped rare-earth-doped fiber laser technologies are currently among the best sources for high power applications. Theses extremely compact and robust sources appoint them as good candidate for aeronautical and space applications. The double-clad (DC) fiber converts the poor beamquality of high-power large-area pump diodes from the 1st cladding to laser light at another wavelength guided in an active single-mode core. High-power coherent MOPA (Master Oscillator Power Amplifier) sources (several 10W CW or several 100W in pulsed regime) will soon be achieved. Unfortunately it also brings nonlinear effects which quickly impairs output signal distortions. Stimulated Brillouin scattering (SBS) and optical parametric amplification (OPA) have been shown to be strong limitations. Based on amplifier modeling and experiments we discuss the performances of these sources.

A Novel Nanosecond Pulsed Power Unit for the Formation of ·OH in Water

Science.gov (United States)

Li, Shengli; Hu, Sheng; Zhang, Han

2012-04-01

A novel nanosecond pulsed power unit was developed for plasma treatment of wastewater, based on the theory of magnetic pulse compression and semiconductor opening switch (SOS). The peak value, rise time and pulse duration of the output voltage were observed to be -51 kV, 60 ns and 120 ns, respectively. The concentrations of ·OH generated by the novel nanosecond pulsed plasma power were determined using the method of high-performance liquid chromatography (HPLC). The results showed that the concentrations of ·OH increased with the increase in peak voltage, and the generation rates of ·OH were 4.1 × 10-10 mol/s, 5.7 × 10-10 mol/s, and 7.7 × 10-10 mol/s at 30 kV, 35 kV, and 40 kV, respectively. The efficiency of OH generation was found to be independent of the input parameters for applied power, with an average value of 3.23×10-12 mol/J obtained.

A Novel Nanosecond Pulsed Power Unit for the Formation of ·OH in Water

International Nuclear Information System (INIS)

Li Shengli; Hu Sheng; Zhang Han

2012-01-01

A novel nanosecond pulsed power unit was developed for plasma treatment of wastewater, based on the theory of magnetic pulse compression and semiconductor opening switch (SOS). The peak value, rise time and pulse duration of the output voltage were observed to be -51 kV, 60 ns and 120 ns, respectively. The concentrations of ·OH generated by the novel nanosecond pulsed plasma power were determined using the method of high-performance liquid chromatography (HPLC). The results showed that the concentrations of ·OH increased with the increase in peak voltage, and the generation rates of ·OH were 4.1 × 10 -10 mol/s, 5.7 × 10 -10 mol/s, and 7.7 × 10 -10 mol/s at 30 kV, 35 kV, and 40 kV, respectively. The efficiency of OH generation was found to be independent of the input parameters for applied power, with an average value of 3.23×10 -12 mol/J obtained. (plasma technology)

Repetitive transcranial magnetic stimulator with controllable pulse parameters

Science.gov (United States)

Peterchev, Angel V.; Murphy, David L.; Lisanby, Sarah H.

2011-06-01

The characteristics of transcranial magnetic stimulation (TMS) pulses influence the physiological effect of TMS. However, available TMS devices allow very limited adjustment of the pulse parameters. We describe a novel TMS device that uses a circuit topology incorporating two energy storage capacitors and two insulated-gate bipolar transistor (IGBT) modules to generate near-rectangular electric field pulses with adjustable number, polarity, duration, and amplitude of the pulse phases. This controllable pulse parameter TMS (cTMS) device can induce electric field pulses with phase widths of 10-310 µs and positive/negative phase amplitude ratio of 1-56. Compared to conventional monophasic and biphasic TMS, cTMS reduces energy dissipation up to 82% and 57% and decreases coil heating up to 33% and 41%, respectively. We demonstrate repetitive TMS trains of 3000 pulses at frequencies up to 50 Hz with electric field pulse amplitude and width variability less than the measurement resolution (1.7% and 1%, respectively). Offering flexible pulse parameter adjustment and reduced power consumption and coil heating, cTMS enhances existing TMS paradigms, enables novel research applications and could lead to clinical applications with potentially enhanced potency.

Generation of high-power terahertz radiation by femtosecond-terawatt lasers

International Nuclear Information System (INIS)

Nashima, Shigeki; Hosoda, Makoto; Daido, Hiroyuki

2007-01-01

We observed electromagnetic waves in the terahertz (THz) frequency range from a Ti foil excited by tabletop terawatt (T-cube) laser pulses. The radiation power was increased drastically with increasing its laser power. We also investigated the polarization characteristics of the sub-terahertz wave. It is found that the polarization of the radiated sub-terahertz waves was parallel to the incident beam plane, which is independent on the pump laser polarization. These results indicate transient electric field to the incident plane is generated by laser-plasma interaction, i.e., laser wake field and coherent plasma wave. (author)

Laboratory manual for pulse-width modulated DC-DC power converters

CERN Document Server

Kazimierczuk, Marian K

2015-01-01

Designed to complement a range of power electronics study resources, this unique lab manual helps students to gain a deep understanding of the operation, modeling, analysis, design, and performance of pulse-width modulated (PWM) DC-DC power converters.  Exercises focus on three essential areas of power electronics: open-loop power stages; small-signal modeling, design of feedback loops and PWM DC-DC converter control schemes; and semiconductor devices such as silicon, silicon carbide and gallium nitride. Meeting the standards required by industrial employers, the lab manual combines program

Proton polarization in photo-excited aromatic molecule at room temperature enhanced by intense optical source and temperature control

Energy Technology Data Exchange (ETDEWEB)

Sakaguchi, S., E-mail: sakaguchi@phys.kyushu-u.ac.jp [Department of Physics, Kyushu University, Fukuoka 812-8581 (Japan); Uesaka, T. [RIKEN Nishina Center, Saitama 351-0198 (Japan); Kawahara, T. [Department of Physics, Toho University, Chiba 274-8510 (Japan); Ogawa, T. [RIKEN Advanced Science Institute, Saitama 351-0198 (Japan); Tang, L. [Center for Nuclear Study, University of Tokyo, Tokyo 113-0001 (Japan); Teranishi, T. [Department of Physics, Kyushu University, Fukuoka 812-8581 (Japan); Urata, Y.; Wada, S. [RIKEN Advanced Science Institute, Saitama 351-0198 (Japan); Wakui, T. [Cyclotron and Radioisotope Center (CYRIC), Tohoku University, Miyagi 980-8578 (Japan)

2013-12-15

Highlights: • Proton polarization in p-terphenyl at room-temperature is enhanced by a factor of 3. • Intense laser and temperature control are critically important for high polarization. • Optimization of time structure of laser pulse is effective for further improvement. -- Abstract: Proton polarization at room temperature, produced in a p-terphenyl crystal by using electron population difference in a photo-excited triplet state of pentacene, was enhanced by utilizing an intense laser with an average power of 1.5 W. It was shown that keeping the sample temperature below 300 K is critically important to prevent the rise of the spin–lattice relaxation rate caused by the laser heating. It is also reported that the magnitude of proton polarization strongly depends on the time structure of the laser pulse such as its width and the time interval between them.

Mean energy polarized neutron source

International Nuclear Information System (INIS)

Aleshin, V.A.; Zaika, N.I.; Kolotyj, V.V.; Prokopenko, V.S.; Semenov, V.S.

1988-01-01

Physical bases and realization scheme of a pulsed source of polarized neutrons with the energy of up to 75 MeV are described. The source comprises polarized deuteron source, transport line, low-energy ion and axial injector to the accelerator, U-240 isochronous cyclotron, targets for polarized neutron production, accelerated deuteron transport line and flight bases. The pulsed source of fast neutrons with the energy of up to 75 MeV can provide for highly polarized neutron beams with the intensity by 2-3 orders higher than in the most perfect source of this range which allows one to perform various experiments with high efficiency and energy resolution. 9 refs.; 1 fig

Electromagnetic pulse research on electric power systems: Program summary and recommendations

Energy Technology Data Exchange (ETDEWEB)

Barnes, P.R.; McConnell, B.W.; Van Dyke, J.W. (Oak Ridge National Lab., TN (United States)); Tesche, F.M. (Tesche (F.M.), Dallas, TX (United States)); Vance, E.F. (Vance (E.F.), Fort Worth, TX (United States))

1993-01-01

A single nuclear detonation several hundred kilometers above the central United States will subject much of the nation to a high-altitude electromagnetic pulse (BENT). This pulse consists of an intense steep-front, short-duration transient electromagnetic field, followed by a geomagnetic disturbance with tens of seconds duration. This latter environment is referred to as the magnetohydrodynamic electromagnetic pulse (NMENT). Both the early-time transient and the geomagnetic disturbance could impact the operation of the nation's power systems. Since 1983, the US Department of Energy has been actively pursuing a research program to assess the potential impacts of one or more BENT events on the nation's electric energy supply. This report summarizes the results of that program and provides recommendations for enhancing power system reliability under HENT conditions. A nominal HENP environment suitable for assessing geographically large systems was developed during the program and is briefly described in this report. This environment was used to provide a realistic indication of BEMP impacts on electric power systems. It was found that a single high-altitude burst, which could significantly disturb the geomagnetic field, may cause the interconnected power network to break up into utility islands with massive power failures in some areas. However, permanent damage would be isolated, and restoration should be possible within a few hours. Multiple bursts would likely increase the blackout areas, component failures, and restoration time. However, a long-term blackout of many months is unlikely because major power system components, such as transformers, are not likely to be damaged by the nominal HEND environment. Moreover, power system reliability, under both HENT and normal operating conditions, can be enhanced by simple, and often low cost, modifications to current utility practices.

Predicting the effect of relaxation during frequency-selective adiabatic pulses

Science.gov (United States)

Pfaff, Annalise R.; McKee, Cailyn E.; Woelk, Klaus

2017-11-01

Adiabatic half and full passages are invaluable for achieving uniform, B1-insensitive excitation or inversion of macroscopic magnetization across a well-defined range of NMR frequencies. To accomplish narrow frequency ranges with adiabatic pulses (computer-calculated data with experimental results demonstrates that, in non-viscous, small-molecule fluids, it is possible to model magnetization and relaxation by considering standard T1 and T2 relaxation in the traditional rotating frame. The proposed model is aimed at performance optimizations of applications in which these pulses are employed. It differs from previous reports which focused on short high-power adiabatic pulses and relaxation that is governed by dipole-dipole interactions, cross polarization, or chemical exchange.

A low-power, CMOS peak detect and hold circuit for nuclear pulse spectroscopy

International Nuclear Information System (INIS)

Ericson, M.N.; Simpson, M.L.; Britton, C.L.; Allen, M.D.; Kroeger, R.A.; Inderhees, S.E.

1994-01-01

A low-power CMOS peak detecting track and hold circuit optimized for nuclear pulse spectroscopy is presented. The circuit topology eliminates the need for a rectifying diode, reducing the effect of charge injection into the hold capacitor, incorporates a linear gate at the input to prevent pulse pileup, and uses dynamic bias control that minimizes both pedestal and droop. Both positive-going and negative-going pulses are accommodated using a complementary set of track and hold circuits. Full characterization of the design fabricated in 1.2μm CMOS including dynamic range, integral nonlinearity, droop rate, pedestal, and power measurements is presented. Additionally, analysis and design approaches for optimization of operational characteristics are discussed

Effects of nuclear electromagnetic pulse (EMP) on nuclear power plants

International Nuclear Information System (INIS)

Barnes, P.R.; Manweiler, R.W.; Davis, R.R.

1977-09-01

The electromagnetic pulse (EMP) from a high-altitude nuclear detonation consists of a transient pulse of high intensity electromagnetic fields. These intense fields induce current and voltage transients in electrical conductors. Although most nuclear power plant cables are not directly exposed to these fields, the attenuated EMP fields that propagate into the plant will couple some EMP energy to these cables. The report predicts the probable effects of the EMP transients that could be induced in critical circuits of safety-related systems. It was found that the most likely consequence of EMP for nuclear plants is an unscheduled shutdown. EMP could prolong the shutdown period by the unnecessary actuation of certain safety systems. In general, EMP could be a nuisance to nuclear power plants, but it is not considered a serious threat to plant safety

Formation of nanosecond SBS-compressed pulses for pumping an ultra-high power parametric amplifier

Science.gov (United States)

Kuz’min, A. A.; Kulagin, O. V.; Rodchenkov, V. I.

2018-04-01

Compression of pulsed Nd : glass laser radiation under stimulated Brillouin scattering (SBS) in perfluorooctane is investigated. Compression of 16-ns pulses at a beam diameter of 30 mm is implemented. The maximum compression coefficient is 28 in the optimal range of laser pulse energies from 2 to 4 J. The Stokes pulse power exceeds that of the initial laser pulse by a factor of about 11.5. The Stokes pulse jitter (fluctuations of the Stokes pulse exit time from the compressor) is studied. The rms spread of these fluctuations is found to be 0.85 ns.

Pulsed Power for a Dynamic Transmission Electron Microscope

Energy Technology Data Exchange (ETDEWEB)

dehope, w j; browning, n; campbell, g; cook, e; king, w; lagrange, t; reed, b; stuart, b; Shuttlesworth, R; Pyke, B

2009-06-25

Lawrence Livermore National Laboratory (LLNL) has converted a commercial 200kV transmission electron microscope (TEM) into an ultrafast, nanoscale diagnostic tool for material science studies. The resulting Dynamic Transmission Electron Microscope (DTEM) has provided a unique tool for the study of material phase transitions, reaction front analyses, and other studies in the fields of chemistry, materials science, and biology. The TEM's thermionic electron emission source was replaced with a fast photocathode and a laser beam path was provided for ultraviolet surface illumination. The resulting photoelectron beam gives downstream images of 2 and 20 ns exposure times at 100 and 10 nm spatial resolution. A separate laser, used as a pump pulse, is used to heat, ignite, or shock samples while the photocathode electron pulses, carefully time-synchronized with the pump, function as probe in fast transient studies. The device functions in both imaging and diffraction modes. A laser upgrade is underway to make arbitrary cathode pulse trains of variable pulse width of 10-1000 ns. Along with a fast e-beam deflection scheme, a 'movie mode' capability will be added to this unique diagnostic tool. This talk will review conventional electron microscopy and its limitations, discuss the development and capabilities of DTEM, in particularly addressing the prime and pulsed power considerations in the design and fabrication of the DTEM, and conclude with the presentation of a deflector and solid-state pulser design for Movie-Mode DTEM.

Pulsed Power for a Dynamic Transmission Electron Microscope

International Nuclear Information System (INIS)

DeHope, W.J.; Browning, N.; Campbell, G.; Cook, E.; King, W.; Lagrange, T.; Reed, B.; Stuart, B.; Shuttlesworth, R.; Pyke, B.

2009-01-01

Lawrence Livermore National Laboratory (LLNL) has converted a commercial 200kV transmission electron microscope (TEM) into an ultrafast, nanoscale diagnostic tool for material science studies. The resulting Dynamic Transmission Electron Microscope (DTEM) has provided a unique tool for the study of material phase transitions, reaction front analyses, and other studies in the fields of chemistry, materials science, and biology. The TEM's thermionic electron emission source was replaced with a fast photocathode and a laser beam path was provided for ultraviolet surface illumination. The resulting photoelectron beam gives downstream images of 2 and 20 ns exposure times at 100 and 10 nm spatial resolution. A separate laser, used as a pump pulse, is used to heat, ignite, or shock samples while the photocathode electron pulses, carefully time-synchronized with the pump, function as probe in fast transient studies. The device functions in both imaging and diffraction modes. A laser upgrade is underway to make arbitrary cathode pulse trains of variable pulse width of 10-1000 ns. Along with a fast e-beam deflection scheme, a 'movie mode' capability will be added to this unique diagnostic tool. This talk will review conventional electron microscopy and its limitations, discuss the development and capabilities of DTEM, in particularly addressing the prime and pulsed power considerations in the design and fabrication of the DTEM, and conclude with the presentation of a deflector and solid-state pulser design for Movie-Mode DTEM

Polarity inversion of AlN film grown on nitrided a-plane sapphire substrate with pulsed DC reactive sputtering

Directory of Open Access Journals (Sweden)

Marsetio Noorprajuda

2018-04-01

Full Text Available The effect of oxygen partial pressure (PO2 on polarity and crystalline quality of AlN films grown on nitrided a-plane sapphire substrates by pulsed direct current (DC reactive sputtering was investigated as a fundamental study. The polarity inversion of AlN from nitrogen (−c-polarity to aluminum (+c-polarity occurred during growth at a high PO2 of 9.4×103 Pa owing to Al-O octahedral formation at the interface of nitrided layer and AlN sputtered film which reset the polarity of AlN. The top part of the 1300 nm-thick AlN film sputtered at the high PO2 was polycrystallized. The crystalline quality was improved owing to the high kinetic energy of Al sputtered atom in the sputtering phenomena. Thinner AlN films were also fabricated at the high PO2 to eliminate the polycrystallization. For the 200 nm-thick AlN film sputtered at the high PO2, the full width at half-maximum values of the AlN (0002 and (10−12 X-ray diffraction rocking curves were 47 and 637 arcsec, respectively.

Control and performance improvements of a pulse compressor in use for testing accelerating structures at high power

Directory of Open Access Journals (Sweden)

Benjamin Woolley

2017-10-01

Full Text Available New developments relating to compact X-band, SLED-I type pulse compressors being developed at CERN for testing high gradient structures are described. Pulse compressors of interest take rf pulses from one or more high power klystrons with duration typically >1.5  μs and deliver up to 5 times the input power for a shorter duration <250  ns. Time domain models for pulse compressor operation with low level rf (LLRF control have been developed. Input drive amplitude and phase for each pulse is evolved with a control algorithm from the pulse compressor output for previous pulses. The goal is to deliver precise amplitude for pulses to test stands and precise amplitude and phase for pulses to accelerator systems. Control algorithms have been developed and validated experimentally.

Mathematical solutions of rate equations of a laser-diode end-pumped passively Q-switched and mode locked Nd-laser with Cr4+:YAG polarized saturable absorber

International Nuclear Information System (INIS)

Abdul Ghani, B.; Hammadi, M.

2012-01-01

The intracavity frequency-doubling (IFD) of a simultaneous passively Q-switched mode-locked diode-pumped Nd 3 + - laser is studied with a polarized isotropic Cr 4 +: YAG saturable absorber. A general recurrence formula for the mode-locked pulses under the Q-switched envelope at fundamental wavelength has been reconstructed in order to analyze the temporal shape behavior of a single Q-switched envelope with mode-locking pulse trains. This formula has been derived taking into account the impact of the IFD and polarized Cr 4 +: YAG saturable absorber.The presented mathematical model describes the self-induced anisotropy appeared in the polarized Cr 4 +: YAG in the nonlinear stage of the giant pulse formation. For the anisotropic Nd 3 +: YVO 4 active medium, the generated polarized waves are assumed to be fixed through the lasing cycle. Besides, the maximum absorber initial transmission and the minimum mirror reflectivity values have been determined from the second threshold criterion. The calculated numerical results demonstrate the impact of the variation of the input laser parameters (rotational angle of the polarized crystal, absorber initial transmission and the output mirror reflectivity) on the characteristics of the output laser pulse (SH peak power, pulse width, pulse duration and shift pulse position of central mode). The calculated numerical results in this work is in good qualitative and quantitative agreement with the available experimental data reported in the references. (author)

Optimized design of polarizers with low ohmic loss and any polarization state for the 28 GHz QUEST ECH/ECCD system

Energy Technology Data Exchange (ETDEWEB)

Tsujimura, Toru Ii, E-mail: tsujimura.tohru@nifs.ac.jp [National Institute for Fusion Science, National Institutes of Natural Sciences, Toki 509-5292 (Japan); Idei, Hiroshi [Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580 (Japan); Kubo, Shin; Kobayashi, Sakuji [National Institute for Fusion Science, National Institutes of Natural Sciences, Toki 509-5292 (Japan)

2017-01-15

Highlights: • Ohmic loss was calculated on the grooved mirror surface in simulated polarizers. • Polarizers with a low ohmic loss feature were optimally designed for 28 GHz. • Smooth rounded-rectangular grooves were made by mechanical machining. • The designed polarizers can realize all polarization states. - Abstract: In a high-power long-pulse millimeter-wave transmission line for electron cyclotron heating and current drive (ECH/ECCD), the ohmic loss on the grooved mirror surface of polarizers is one of the important issues for reducing the transmission loss. In this paper, the ohmic loss on the mirror surface is evaluated in simulated real-scale polarizer miter bends for different groove parameters under a linearly-polarized incident wave excitation. The polarizers with low ohmic loss are optimally designed for a new 28 GHz transmission line on the QUEST spherical tokamak. The calculated optimum ohmic loss is restricted to only less than 1.5 times as large as the theoretical loss for a copper flat mirror at room temperature. The copper rounded-rectangular grooves of the polarizers were relatively easy to make smooth in mechanical machining and the resultant surface roughness was not more than 0.15 μm, which is only 0.38 times as large as the skin depth. The combination of the designed elliptical polarizer and the polarization rotator can also realize any polarization state of the reflected wave.

Quantum coherent π-electron rotations in a non-planar chiral molecule induced by using a linearly polarized UV laser pulse

Science.gov (United States)

Mineo, Hirobumi; Fujimura, Yuichi

2015-06-01

We propose an ultrafast quantum switching method of π-electron rotations, which are switched among four rotational patterns in a nonplanar chiral aromatic molecule (P)-2,2’- biphenol and perform the sequential switching among four rotational patterns which are performed by the overlapped pump-dump laser pulses. Coherent π-electron dynamics are generated by applying the linearly polarized UV pulse laser to create a pair of coherent quasidegenerated excited states. We also plot the time-dependent π-electron ring current, and discussed ring current transfer between two aromatic rings.

Active high-power RF pulse compression using optically switched resonant delay lines

International Nuclear Information System (INIS)

Tantawi, S.G.; Ruth, R.D.; Vlieks, A.E.

1996-11-01

The authors present the design and a proof of principle experimental results of an optically controlled high power rf pulse compression system. The design should, in principle, handle few hundreds of Megawatts of power at X-band. The system is based on the switched resonant delay line theory. It employs resonant delay lines as a means of storing rf energy. The coupling to the lines is optimized for maximum energy storage during the charging phase. To discharge the lines, a high power microwave switch increases the coupling to the lines just before the start of the output pulse. The high power microwave switch, required for this system, is realized using optical excitation of an electron-hole plasma layer on the surface of a pure silicon wafer. The switch is designed to operate in the TE 01 mode in a circular waveguide to avoid the edge effects present at the interface between the silicon wafer and the supporting waveguide; thus, enhancing its power handling capability

Fields of an ultrashort tightly focused radially polarized laser pulse in a linear response plasma

Science.gov (United States)

Salamin, Yousef I.

2017-10-01

Analytical expressions for the fields of a radially polarized, ultrashort, and tightly focused laser pulse propagating in a linear-response plasma are derived and discussed. The fields are obtained from solving the inhomogeneous wave equations for the vector and scalar potentials, linked by the Lorenz gauge, in a plasma background. First, the scalar potential is eliminated using the gauge condition, then the vector potential is synthesized from Fourier components of an initial uniform distribution of wavenumbers, and the inverse Fourier transformation is carried out term-by-term in a truncated series (finite sum). The zeroth-order term in, for example, the axial electric field component is shown to model a pulse much better than its widely used paraxial approximation counterpart. Some of the propagation characteristics of the fields are discussed and all fields are shown to have manifested the expected limits for propagation in a vacuum.

High-power terahertz optical pulse generation with a dual-wavelength harmonically mode-locked Yb:YAG laser

International Nuclear Information System (INIS)

Zhuang, W Z; Chang, M T; Su, K W; Huang, K F; Chen, Y F

2013-01-01

We report on high-power terahertz optical pulse generation with a dual-wavelength harmonically mode-locked Yb:YAG laser. A semiconductor saturable absorber mirror is developed to achieve synchronously mode-locked operation at two spectral bands centered at 1031.67 and 1049.42 nm with a pulse duration of 1.54 ps and a pulse repetition rate of 80.3 GHz. With a diamond heat spreader to improve the heat removal efficiency, the average output power can be up to 1.1 W at an absorbed pump power of 5.18 W. The autocorrelation traces reveal that the mode-locked pulse is modulated with a beat frequency of 4.92 THz and displays a modulation depth to be greater than 80%. (paper)

Study of Pulsed vs. RF Plasma Properties for Surface Processing Applications

Science.gov (United States)

Tang, Ricky; Hopkins, Matthew; Barnat, Edward; Miller, Paul

2015-09-01

The ability to manipulate the plasma parameters (density, E/N) was previously demonstrated using a double-pulsed column discharge. Experiments extending this to large-surface plasmas of interest to the plasma processing community were conducted. Differences between an audio-frequency pulsed plasma and a radio-frequency (rf) discharge, both prevalent in plasma processing applications, were studied. Optical emission spectroscopy shows higher-intensity emission in the UV/visible range for the pulsed plasma comparing to the rf plasma at comparable powers. Data suggest that the electron energy is higher for the pulsed plasma leading to higher ionization, resulting in increased ion density and ion flux. Diode laser absorption measurements of the concentration of the 1S5 metastable and 1S4 resonance states of argon (correlated with the plasma E/N) provide comparisons between the excitation/ionization states of the two plasmas. Preliminary modeling efforts suggest that the low-frequency polarity switch causes a much more abrupt potential variation to support interesting transport phenomena, generating a ``wave'' of higher temperature electrons leading to more ionization, as well as ``sheath capture'' of a higher density bolus of ions that are then accelerated during polarity switch.

Powerful nanosecond pulse train generator

International Nuclear Information System (INIS)

Isakov, I.F.; Logachev, E.I.; Opekunov, M.S.; Pechenkin, S.A.; Remnev, G.E.; Usov, Yu.P.

1987-01-01

A generator permitting to shape on the load pulsed with the repetition frequency of 10 3 -10 6 Hz and more is described. The amplitude of shaped voltage pulses is up to 150 kV at pulse duration equal to 50 ns. The generator comprises connected in-series with the load two shaping and two transmission lines realized on the base of the KVI-300 low-ohmic cable. The shaping lines are supplied from two independently connected pulse voltage generators for obtaining time interval between pulses > 10 -6 s; they may be also supplied from one generator for obtaining time interval -6 s. At the expense of reducing losses in the discharge circuit the amplitude of the second pulse grows with increase of time interval between pulses up to 300 ns, further on the curve flat-topping exists. The described generator is used in high-current accelerators, in which the primary negative pulse results in generation of explosive-emission plasma, and the second positive pulse provides ion beam shaping including ions of heavy metal used for production of a potential electrode. The generator multipulse mode is used for successive ion acceleration in the transport system

Detection of low caloric power of coal by pulse fast-thermal neutron analysis

International Nuclear Information System (INIS)

Gu De-shan; Sang Hai-feng; Qiao Shuang; Liu Yu-ren, Liu Lin-mao; Jing Shi-wei; Chinese Academy of Sciences, Changchun

2004-01-01

Analysis method and principle of pulse fast-thermal neutron analysis (PFTNA) are introduced. A system for the measurement of low caloric power of coal by PFTNA is also presented. The 14 MeV pulse neutron generator and BGO detector and 4096 MCA were applied in this system. A multiple linear regression method applied to the data solved the interferential problem of multiple elements. The error of low caloric power between chemical analysis and experiment was less than 0.4 MJ/kg. (author)

Studies of Effect Analysis of Electromagnetic Pulses (EMP) in Operating Nuclear Power Plants (NPP)

Energy Technology Data Exchange (ETDEWEB)

Ye, Song Hae; Ryu, Ho Sun; Kim, Min Yi; Lee, Eui Jong [KHNP, Daejeon (Korea, Republic of)

2016-05-15

The effect analysis of electromagnetic pulses (EMPs) has been studied for the past year by the Central Research Institute of Korea Hydro Nuclear Power Co. (KHNP) in order to better establish safety measures in operating nuclear power plants. What is an electromagnetic pulse (EMP)? As a general term for high-power electromagnetic radiation, it refers to strong electromagnetic pulses that destroy only electronic equipment devices in a short period without loss of life. The effect analysis of EMPs in operating NPPs and their corresponding safety measures in terms of selecting target devices against EMP impact have been examined in this paper. In general, domestic nuclear power plants do apply the design of fail-safe concepts. For example, if key instruments of a system fail because of EMPs, the control rods of a nuclear reactor are dropped automatically in order to maintain safe conditions of the NPP. Reactor cooling presents no problem because the diesel generator will adopt the analog starting circuit least affected by the electromagnetic waves.

A pulsed power hydrodynamics approach to exploring properties of warm dense matter

Energy Technology Data Exchange (ETDEWEB)

Reinovsky, Robert Emil [Los Alamos National Laboratory

2008-01-01

Pulsed Power Hydrodynamics, as an application of low-impedance, pulsed power, and high magnetic field technology developed over the last decade to study advanced hydrodynamic problems, instabilities, turbulence, and material properties, can potentially be applied to the study of the behavior and properties of warm dense matter (WDM) as well. Exploration of the properties, such as equation of state and conductivity, of warm dense matter is an emerging area of study focused on the behavior of matter at density near solid density (from 10% of solid density to a few times solid density) and modest temperatures ({approx}1-10 eV). Warm dense matter conditions can be achieved by laser or particle beam heating of very small quantities of matter on timescales short compared to the subsequent hydrodynamic expansion timescales (isochoric heating) and a vigorous community of researchers is applying these techniques using petawatt scale laser systems, but the microscopic size scale of the WDM produced in this way limits access to some physics phenomena. Pulsed power hydrodynamics techniques, either through high convergence liner compression of a large volume, modest density, low temperature plasma to densities approaching solid density or through the explosion and subsequent expansion of a conductor (wire) against a high pressure (density) gas background (isobaric expansion) techniques both offer the prospect for producing warm dense matter in macroscopic quantities. However, both techniques demand substantial energy, proper power conditioning and delivery, and an understanding of the hydrodynamic and instability processes that limit each technique. Similarly, liner compression of normal density material, perhaps using multiple reflected shocks can provide access to the challenging region above normal density -- again with the requirement of very large amounts of driving energy. In this paper we will provide an introduction to techniques that might be applied to explore this

The development of long pulse high voltage power supply for MNI-1U neutral beam injector

International Nuclear Information System (INIS)

Detai Wang

1989-01-01

A high power long pulse high voltage power supply (HVPS) for MNI- 1 U neutral beam injector (NBI) is described. This HVPS is used as a switching regulator with a duty cycle of 1/100, the specifications of circuit are as follows, output pulse voltage 50kv, pulse current 30A, pulse width 50ms, rise-time and fall-time of the voltage are less than 25 μs, stability of the pulse flat is better than 0.5%, regulation response time of the pulse voltage less than 30 μs can be attained. It is also used as a stable DC HVPS, output voltage is 1 to 100kv, current is 1 to 5A. If regulation tube is shunted with high power resistor in parallel, the current can be extended to 10 A, stability of the output voltage or current is better than 0.1%. Now, the HVPS has been put into operation for MNI- 1 U NBI and PIG ion source made in French. 3 refs., 5 figs

Development of compact rapid charging power supply for capacitive energy storage in pulsed power drivers.

Science.gov (United States)

Sharma, Surender Kumar; Shyam, Anurag

2015-02-01

High energy capacitor bank is used for primary electrical energy storage in pulsed power drivers. The capacitors used in these pulsed power drivers have low inductance, low internal resistance, and less dc life, so it has to be charged rapidly and immediately discharged into the load. A series resonant converter based 45 kV compact power supply is designed and developed for rapid charging of the capacitor bank with constant charging current up to 150 mA. It is short circuit proof, and zero current switching technique is used to commute the semiconductor switch. A high frequency resonant inverter switching at 10 kHz makes the overall size small and reduces the switching losses. The output current of the power supply is limited by constant on-time and variable frequency switching control technique. The power supply is tested by charging the 45 kV/1.67 μF and 15 kV/356 μF capacitor banks. It has charged the capacitor bank up to rated voltage with maximum charging current of 150 mA and the average charging rate of 3.4 kJ/s. The output current of the power supply is limited by reducing the switching frequency at 5 kHz, 3.3 kHz, and 1.7 kHz and tested with 45 kV/1.67 μF capacitor bank. The protection circuit is included in the power supply for over current, under voltage, and over temperature. The design details and the experimental testing results of the power supply for resonant current, output current, and voltage traces of the power supply with capacitive, resistive, and short circuited load are presented and discussed.

Thermal Simulation of Switching Pulses in an Insulated Gate Bipolar Transistor (IGBT) Power Module

Science.gov (United States)

2015-02-01

executed with SolidWorks Flow Simulation , a computational fluid-dynamics code. The graph in Fig. 2 shows the timing and amplitudes of power pulses...defined a convective flow of air perpendicular to the bottom surface of the mounting plate, with a velocity of 10 ft/s. The thermal simulations were...Thermal Simulation of Switching Pulses in an Insulated Gate Bipolar Transistor (IGBT) Power Module by Gregory K Ovrebo ARL-TR-7210

Dynamics of the spectrum of a self-modulated powerful laser pulse in an underdense plasma

International Nuclear Information System (INIS)

Andreev, N.E.; Kirsanov, V.I.; Sakharov, A.S.

1997-01-01

The evolution of the spectrum of a powerful laser pulse during its self-modulation in an underdense plasma is studied analytically and numerically. It is shown that, in the early stages of the self-modulation instability, the linear theory gives a qualitatively correct description of the dynamics of the pulse spectrum in most cases. Depending on the parameters of the laser pulse and of the plasma, this spectrum contains either Stocks satellites (downshifted from the fundamental frequency to a value equal to the plasma frequency), or both Stocks and anti-Stocks satellites of the fundamental frequency. When the three-dimensional mechanism for the instability is dominant and the pulse power is close to the critical power for relativistic self-focusing, the numerical calculations show that the intensity of the blue satellite exceeds the intensity of the red one. This specific feature of the spectrum, which does not arise when the instability is one-dimensional, cannot be explained in terms of the linear para-axial theory, and can be used to identify the three-dimensional mechanism for the instability in experiments on the self-modulation of powerful laser pulses. It is shown that the transition to the nonlinear stage of the instability is accompanied by the occurrence of cascades (at frequencies separated from the laser carrier frequency by intervals equal to an integer number of plasma frequencies) in the spectrum of the laser pulse

Few-cycle isolated attosecond pulses

International Nuclear Information System (INIS)

Sansone, G.; Benedetti, E.; Calegari, F.; Stagira, S.; Vozzi, C.; Silvestri De, S.; Nisoli, M.

2006-01-01

Complete test of publication follows. In the last few years the field of attosecond science has shown impressive and rapid progress, mainly due to the introduction of novel experimental methods for the characterization of extreme ultraviolet (XUV) pulses and attosecond electron wave packets. This development has been also triggered by significant improvements in the control of the electric field of the driving infrared pulses. Particularly interesting for the applications is the generation of isolated attosecond XUV pulses using few-cycle driving pulses. In this case significant progresses have been achieved thanks to the stabilization of the carrier-envelope phase (CEP) of amplified light pulses. In this work we demonstrate that the polarization gating (PG) method with few-cycle phase-stabilized driving pulses allows one to generate few-cycle isolated attosecond pulses tunable on a very broad spectral region. The PG method is based on temporal modulation of the ellipticity of a light pulse, which confines the XUV emission in the temporal gate where the polarization is close to linear. The time-dependent polarization of phase-stabilized sub-6-fs pulses, generated by the hollow fiber technique, has been obtained using two birefringent plates. It is possible to create a linear polarization gate, whose position is imposed by the intensity profile of the pulse whilst the emission time is linked to the CEP of the electric field. The pulses have been analyzed by using a flat-field spectrometer. Continuous XUV spectra, corresponding to the production of isolated attosecond pulses, have been generated for particular CEP values. Upon changing the rotation of the first plate it was possible to tune the XUV emission in a broad spectra range. We have then achieved a complete temporal characterization of the generated isolated attosecond pulses using frequency-resolved optical gating for complete reconstruction of attosecond bursts (FROG CRAB). The measured parabolic phase

All-fiber polarization switch

Science.gov (United States)

Knape, Harald; Margulis, Walter

2007-03-01

We report an all-fiber polarization switch made out of silica-based microstructured fiber suitable for Q-switching all-fiber lasers. Nanosecond high-voltage pulses are used to heat and expand an internal electrode to cause λ/2-polarization rotation in less than 10 ns for 1.5 μm light. The 10 cm long component has an experimentally measured optical insertion loss of 0.2 dB and a 0-10 kHz repetition frequency capacity and has been durability tested for more than 109 pulses.

Conceptual designs of two petawatt-class pulsed-power accelerators for high-energy-density-physics experiments

OpenAIRE

W. A. Stygar; T. J. Awe; J. E. Bailey; N. L. Bennett; E. W. Breden; E. M. Campbell; R. E. Clark; R. A. Cooper; M. E. Cuneo; J. B. Ennis; D. L. Fehl; T. C. Genoni; M. R. Gomez; G. W. Greiser; F. R. Gruner

2015-01-01

We have developed conceptual designs of two petawatt-class pulsed-power accelerators: Z 300 and Z 800. The designs are based on an accelerator architecture that is founded on two concepts: single-stage electrical-pulse compression and impedance matching [Phys. Rev. ST Accel. Beams 10, 030401 (2007)]. The prime power source of each machine consists of 90 linear-transformer-driver (LTD) modules. Each module comprises LTD cavities connected electrically in series, each of which is powered by 5-G...

Steady-state pulses and superradiance in short-wavelength, swept-gain amplifiers

International Nuclear Information System (INIS)

Bonifacio, R.; Hopf, F.A.; Meystre, P.; Scully, M.O.

1975-01-01

The steady-state behavior of amplifiers in which the excitation is swept at the speed of light is discussed in the semiclassical approximation. In the present work the case where the decay time of the population is comparable to that of the polarization is examined. Pulse propagation is shown to obey a generalized sine-Gordon equation which contains the effects of atomic relaxations. The analytical expression of the steady-state pulses (SSP) gives two threshold conditions. In the region of limited gain the SSP is a broad pulse with small area which can be obtained by small signal theory. In the second region of high gain the SSP is the superradiant π pulse. Its pulse power is not limited as in usual superradiant theory because, as is shown, for a swept excitation the cooperation-length limit does not exist

High-throughput machining using high average power ultrashort pulse lasers and ultrafast polygon scanner

Science.gov (United States)

Schille, Joerg; Schneider, Lutz; Streek, André; Kloetzer, Sascha; Loeschner, Udo

2016-03-01

In this paper, high-throughput ultrashort pulse laser machining is investigated on various industrial grade metals (Aluminium, Copper, Stainless steel) and Al2O3 ceramic at unprecedented processing speeds. This is achieved by using a high pulse repetition frequency picosecond laser with maximum average output power of 270 W in conjunction with a unique, in-house developed two-axis polygon scanner. Initially, different concepts of polygon scanners are engineered and tested to find out the optimal architecture for ultrafast and precision laser beam scanning. Remarkable 1,000 m/s scan speed is achieved on the substrate, and thanks to the resulting low pulse overlap, thermal accumulation and plasma absorption effects are avoided at up to 20 MHz pulse repetition frequencies. In order to identify optimum processing conditions for efficient high-average power laser machining, the depths of cavities produced under varied parameter settings are analyzed and, from the results obtained, the characteristic removal values are specified. The maximum removal rate is achieved as high as 27.8 mm3/min for Aluminium, 21.4 mm3/min for Copper, 15.3 mm3/min for Stainless steel and 129.1 mm3/min for Al2O3 when full available laser power is irradiated at optimum pulse repetition frequency.

Three types of pulses delivered from a nanotube-mode-locked fiber laser

International Nuclear Information System (INIS)

Yao, X K

2015-01-01

Three types of pulses are experimentally investigated in a switchable normal-dispersion nanotube-mode-locked fiber laser by adjusting polarizer controller and pump power. They are a standard dissipative-soliton (DS), conventional soliton (CS)-like pulse, and noiselike pulse, which correspond to three mode-locking states. The standard DS with a rectangular spectrum possesses a Gaussian-shape pulse. The CS-like operation has a Lorenz shape, and the spectrum involves several sidebands similar to the CS case. For the noiselike pulse with a bell-shaped spectrum, a 317 fs peak rides upon the 132.5 ps pedestal in the autocorrelation trace. The spectra of these three pulse operations are centered at three close wavelengths. The generation of three such different types of pulses in one identical normal- dispersion laser cavity may find an important application for the future of mode-locked laser research. (paper)

Synchronization method of digital pulse power supply for heavy ions accelerator in Lanzhou

International Nuclear Information System (INIS)

Wang Rongkun; Zhao Jiang; Wu Fengjun; Zhang Huajian; Chen Youxin; Huang Yuzhen; Gao Daqing; Zhou Zhongzu; Yan Huaihai; Yan Hongbin

2013-01-01

The performance of the synchrotron depends on its synchronization. A kind of synchronization method of digital pulse power supply in Heavy Ion Research Facility in Lanzhou-Cooler Storage Ring (HIRFL-CSR) was presented in detail, which is a kind of system on a programmable chip (SOPC) based on optical fiber and optical-custom component. The test of the digital power supply was performed and the current wave forms of pulse mode were given. The results show that all targets can meet the design requirements. (authors)

Pulsed-power-supply development for fusion applications: special research support agreement

International Nuclear Information System (INIS)

1980-01-01

This is a final summary describing research and development work carried out by the Center for Electromechanics at The University of Texas at Austin (CEM-UT) for the Department of Energy during calendar years 1978, 1979, and 1980. The general purpose of this special research support program was to conduct research on pulsed power supply development for fusion applications in the areas of homopolar generators (HPGs), tokamak ohmic heating stuides, switching, and pulse compression technology

Electrostatic precipitators for coal thermal power plants energized by means of narrow pulse voltage

Energy Technology Data Exchange (ETDEWEB)

Dinelli, G.; Mattachini, F.; Bogani, V.; Baldacci, A.; Tarli, R. (ENEL-CRTN, Direzione Studi e Ricerche, Milan (Italy) ENEL, VDT Settore Tecnico, Direzione Produzione e Trasmissione, Rome (Italy))

1990-09-01

The efficiency of electrostatic precipitators, widely used in thermal power plants to clean flue gases from solid particulate, is strongly dependent both on the way particles are electrically charged and on the characteristics of the electric field within the interelectrodic space of the precipitator. Such operating may become inadequate under varying particle characteristics and operating conditions of the thermal plant, therefore bringing to a reduction in the precipitator collection efficiency. An innovative technique, by generating a pulsed corona in the precipitator, allows a substantial improvement of both the particle charging and the collection processes and an increase in the operation flexibility of the electrostatic precipitator. The narrow pulse voltage energization has been extensively tested at a coal thermal unit having the electrostatic precipitators equipped with both conventional and pulse power sets. The long duration tests confirmed the following results: 1) high reliability of the pulse power sets and a considerable improvement in the precipitator collection efficiency; 2) a decrease in the particulate emissions, with coals whose ashes are of difficult collection, ranging between 75% and 85% of those with conventional energization; 3) a reduction by a factor of about 5 in the consumption of electric power by the electrostatic precipitation process.

IHEP S-band 45 MW pulse power klystron development

International Nuclear Information System (INIS)

Dong Dong; Zhou Zusheng; Zhang Liang; Li Gangying; Tian Shuangmin

2006-01-01

S-band 45 MW pulse power klystron has been developed in the Institute of High Energy Physics (IHEP) for the Beijing Electron Positron Collider (BEPC) upgrade projects (BEPC-II). This new klystron has 5 cavities in its RF-beam interaction and single RF output window, and the RF output power is 45 MW at 310 kV, the gain is 50 dB, the efficiency 40%. The manufacturing, training and testing of a prototype klystron has been finished in IHEP and RF power 45 MW at 300 kV has been reached. The testing results show that all the parameters of the 45 MW klystron reach the design goal. (authors)

Fast pulsing dynamics of a vertical-cavity surface-emitting laser operating in the low-frequency fluctuation regime

International Nuclear Information System (INIS)

Sciamanna, M.; Rogister, F.; Megret, P.; Blondel, M.; Masoller, C.; Abraham, N. B.

2003-01-01

We analyze the dynamics of a vertical-cavity surface-emitting laser with optical feedback operating in the low-frequency fluctuation regime. By focusing on the fast pulsing dynamics, we show that the two linearly polarized modes of the laser exhibit two qualitatively different behaviors: they emit pulses in phase just after a power dropout and they emit pulses out of phase after the recovery process of the output power. As a consequence, two distinct statistical distributions of the fast pulsating total intensity are observed, either monotonically decaying from the noise level or peaked around the mean intensity value. We further show that gain self-saturation of the lasing transition strongly modifies the shape of the intensity distribution

Fiber Optic Cables for Transmission of High-Power Laser Pulses in Spaceflight Applications

Science.gov (United States)

Thomes, W. J., Jr.; Ott, M. N.; Chuska, R. F.; Switzer, R. C.; Blair, D. E.

2010-01-01

Lasers with high peak power pulses are commonly used in spaceflight missions for a wide range of applications, from LIDAR systems to optical communications. Due to the high optical power needed, the laser has to be located on the exterior of the satellite or coupled through a series of free space optics. This presents challenges for thermal management, radiation resistance, and mechanical design. Future applications will require multiple lasers located close together, which further complicates the design. Coupling the laser energy into a fiber optic cable allows the laser to be relocated to a more favorable position on the spacecraft. 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 our new manufacturing procedures that overcome these issues to permit fiber use with high reliability in these applications. We will also discuss the proper methods for launching the laser pulses into the fiber to avoid damage and how this is being implemented for current spaceflight missions.

Fiber optic cables for transmission of high-power laser pulses in spaceflight applications

Science.gov (United States)

Thomes, W. J.; Ott, M. N.; Chuska, R. F.; Switzer, R. C.; Blair, D. E.

2017-11-01

Lasers with high peak power pulses are commonly used in spaceflight missions for a wide range of applications, from LIDAR systems to optical communications. Due to the high optical power needed, the laser has to be located on the exterior of the satellite or coupled through a series of free space optics. This presents challenges for thermal management, radiation resistance, and mechanical design. Future applications will require multiple lasers located close together, which further complicates the design. Coupling the laser energy into a fiber optic cable allows the laser to be relocated to a more favorable position on the spacecraft. 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 our new manufacturing procedures that overcome these issues to permit fiber use with high reliability in these applications. We will also discuss the proper methods for launching the laser pulses into the fiber to avoid damage and how this is being implemented for current spaceflight missions.

Polymerization of polyethers initiated by irradiation with high power pulsed electron beams

International Nuclear Information System (INIS)

Gerber, V.D.; Tolkachev, V.S.; Chmukh, V.N.

1982-01-01

Air oxygen effect on thin-layer polymerization of polyethers, initiated by irradiation with powerful pulse electron beams is studied using the method of IR-spectrophotometry. The analysis of experimental data has shown that in polyether surface layer polymerization is suppressed by oxygen, concentration of which in the layer remains stable at the expense of diffusion from air during two consequent irradiation pulses

Recent experience in accelerating polarized beam at the AGS

International Nuclear Information System (INIS)

Ratner, L.G.

1988-01-01

The most recent operation of the AGS for polarized protons occurred in December, 1987 and January, 1988. The primary purpose during this period was to tune up the accelerator as soon as possible and to provide a usable polarized beam for high energy physics. We succeeded in providing 1--2 /times/ 10 10 polarized protons per pulse at 18.5 GeV/c with an average polarization of 43 +- 3% and a peak of 52%. The conditions for this run differed in some respects from the previous run done in 1986. Due to problems with the main ring power supply, we were forced to use a back-up MG set which was only capable of 60% of the normal field rate of rise. This, of course enhanced the effect of the depolarizing resonances. A second difference was the fact that a complete horizontal and vertical realignment of the ring magnets was done during the 1987 summer shutdown. In addition, the fast pulsed quadrupole positions were readjusted with respect to the equilibrium orbit. It had been suspected that misalignment of these quads was responsible for large transverse emittance growth in both planes. We will look at the effects of these differences, but the bottom line is that the ''standard correction techniques'' worked as expected. 2 refs., 6 figs

Pulse Power Capability Estimation of Lithium Titanate Oxide-based Batteries

DEFF Research Database (Denmark)

Stroe, Ana-Irina; Swierczynski, Maciej Jozef; Stroe, Daniel Loan

2016-01-01

The pulse power capability (PPC) represents one of the parameters that describe the performance behavior of Lithium-ion batteries independent on the application. Consequently, extended information about the Li-ion battery PPC and its dependence on the operating conditions become necessary. Thus......, this paper analyzes the power capability characteristic of a 13Ah high power Lithium Titanate Oxide-based battery and its dependence on temperature, load current and state-of-charge. Furthermore, a model to predict the discharging PPC of the battery cell at different temperatures and load currents for three...

Interaction of electromagnetic pulse with commercial nuclear-power-plant systems

Energy Technology Data Exchange (ETDEWEB)

Ericson, D.M. Jr.; Strawe, D.F.; Sandberg, S.J.; Jones, V.K.; Rensner, G.D.; Shoup, R.W.; Hanson, R.J.; Williams, C.B.

1983-02-01

This study examines the interaction of the electromagnetic pulse from a high altitude nuclear burst with commercial nuclear power plant systems. The potential vulnerability of systems required for safe shutdown of a specific nuclear power plant are explored. EMP signal coupling, induced plant response and component damage thresholds are established using techniques developed over several decades under Defense Nuclear Agency sponsorship. A limited test program was conducted to verify the coupling analysis technique as applied to a nuclear power plant. The results are extended, insofar as possible, to other nuclear plants.

Interaction of electromagnetic pulse with commercial nuclear-power-plant systems

International Nuclear Information System (INIS)

Ericson, D.M. Jr.; Strawe, D.F.; Sandberg, S.J.; Jones, V.K.; Rensner, G.D.; Shoup, R.W.; Hanson, R.J.; Williams, C.B.

1983-02-01

This study examines the interaction of the electromagnetic pulse from a high altitude nuclear burst with commercial nuclear power plant systems. The potential vulnerability of systems required for safe shutdown of a specific nuclear power plant are explored. EMP signal coupling, induced plant response and component damage thresholds are established using techniques developed over several decades under Defense Nuclear Agency sponsorship. A limited test program was conducted to verify the coupling analysis technique as applied to a nuclear power plant. The results are extended, insofar as possible, to other nuclear plants

A peripheral component interconnect express-based scalable and highly integrated pulsed spectrometer for solution state dynamic nuclear polarization

Energy Technology Data Exchange (ETDEWEB)

He, Yugui; Liu, Chaoyang, E-mail: chyliu@wipm.ac.cn [Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China); State Key Laboratory of Magnet Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); Feng, Jiwen; Wang, Dong; Chen, Fang; Liu, Maili [State Key Laboratory of Magnet Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); Zhang, Zhi; Wang, Chao [State Key Laboratory of Magnet Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); University of Chinese Academy of Sciences, Beijing 100048 (China)

2015-08-15

High sensitivity, high data rates, fast pulses, and accurate synchronization all represent challenges for modern nuclear magnetic resonance spectrometers, which make any expansion or adaptation of these devices to new techniques and experiments difficult. Here, we present a Peripheral Component Interconnect Express (PCIe)-based highly integrated distributed digital architecture pulsed spectrometer that is implemented with electron and nucleus double resonances and is scalable specifically for broad dynamic nuclear polarization (DNP) enhancement applications, including DNP-magnetic resonance spectroscopy/imaging (DNP-MRS/MRI). The distributed modularized architecture can implement more transceiver channels flexibly to meet a variety of MRS/MRI instrumentation needs. The proposed PCIe bus with high data rates can significantly improve data transmission efficiency and communication reliability and allow precise control of pulse sequences. An external high speed double data rate memory chip is used to store acquired data and pulse sequence elements, which greatly accelerates the execution of the pulse sequence, reduces the TR (time of repetition) interval, and improves the accuracy of TR in imaging sequences. Using clock phase-shift technology, we can produce digital pulses accurately with high timing resolution of 1 ns and narrow widths of 4 ns to control the microwave pulses required by pulsed DNP and ensure overall system synchronization. The proposed spectrometer is proved to be both feasible and reliable by observation of a maximum signal enhancement factor of approximately −170 for {sup 1}H, and a high quality water image was successfully obtained by DNP-enhanced spin-echo {sup 1}H MRI at 0.35 T.

Optimization of hybrid power system composed of SMES and flywheel MG for large pulsed load

International Nuclear Information System (INIS)

Niiyama, K.; Yagai, T.; Tsuda, M.; Hamajima, T.

2008-01-01

A superconducting magnetic storage system (SMES) has some advantages such as rapid large power response and high storage efficiency which are superior to other energy storage systems. A flywheel motor generator (FWMG) has large scaled capacity and high reliability, and hence is broadly utilized for a large pulsed load, while it has comparatively low storage efficiency due to high mechanical loss compared with SMES. A fusion power plant such as International Thermo-Nuclear Experimental Reactor (ITER) requires a large and long pulsed load which causes a frequency deviation in a utility power system. In order to keep the frequency within an allowable deviation, we propose a hybrid power system for the pulsed load, which equips the SMES and the FWMG with the utility power system. We evaluate installation cost and frequency control performance of three power systems combined with energy storage devices; (i) SMES with the utility power, (ii) FWMG with the utility power, (iii) both SMES and FWMG with the utility power. The first power system has excellent frequency power control performance but its installation cost is high. The second system has inferior frequency control performance but its installation cost is the lowest. The third system has good frequency control performance and its installation cost is attained lower than the first power system by adjusting the ratio between SMES and FWMG

Medium Power 352 MHZ solid state pulsed RF amplifiers for the CERN LINAC4 Project

CERN Document Server

Broere, J; Gómez Martínez, Y; Rossi, M

2011-01-01

Economic, modular and highly linear pulsed RF amplifiers have recently been developed to be used for the three buncher cavities in the CERN Linac4. The amplifiers are water-cooled and can provide up to 33 kW pulsed RF Power, 1.5 ms pulse length and 50 Hz repetition rate. Furthermore a 60 kW unit is under construction to provide the required RF Power for the debuncher cavity. The concept is based on 1.2 kW RF power modules using the latest 6th generation LDMOS technology. For integration into the CERN control environment the amplifiers have an internal industrial controller, which will provide easy control and extended diagnostic functions. This paper describes the construction, performance, including linearity, phase stability and EMC compliance tests

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

Energy Technology Data Exchange (ETDEWEB)

Galletti, Mario, E-mail: mario.gall22@gmail.com [INFN – LNF, Via Enrico Fermi 40, 00044 Frascati (Italy); Galimberti, Marco [Central Laser Facility, Rutherford Appleton Laboratory, Didcot (United Kingdom); Hooker, Chris [Central Laser Facility, Rutherford Appleton Laboratory, Didcot (United Kingdom); University of Oxford, Oxford (United Kingdom); Chekhlov, Oleg; Tang, Yunxin [Central Laser Facility, Rutherford Appleton Laboratory, Didcot (United Kingdom); Bisesto, Fabrizio Giuseppe [INFN – LNF, Via Enrico Fermi 40, 00044 Frascati (Italy); Curcio, Alessandro [INFN – LNF, Via Enrico Fermi 40, 00044 Frascati (Italy); Sapienza – University of Rome, P.le Aldo Moro, 2, 00185 Rome (Italy); Anania, Maria Pia [INFN – LNF, Via Enrico Fermi 40, 00044 Frascati (Italy); Giulietti, Danilo [Physics Department of the University and INFN, Pisa (Italy)

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. - Highlights: • Integration of the diagnostic tool on high power laser. • Validation of the GROG algorithm in comparison to a well-known commercial available software. • Complete characterization of the GEMINI ultra-short high power laser pulse.

Matching problems in pulse power radial transmission lines

International Nuclear Information System (INIS)

Mittag, K.; Brandelik, A.

1984-12-01

In this report we study the power transfer from a generator along a coaxial transmission line followed by a radial transmission line into a load, which in our application is a pseudo-spark plasma of about one millimeter diameter and about 15 cm in length. First the theoretical background based on transmission line theory is described. Then numerical results are presented. The main conclusion is that when matching the pulse power generator to the pseudo-spark plasma, the effect of the impedance transformation caused by the radial transmission line has to be taken into account. The conditions to obtain an optimal match are described. (orig.) [de

Polarized Electron Beams for Nuclear Physics at the MIT Bates Accelerator Center

CERN Document Server

Farkhondeh, Manouchehr; Franklin, Wilbur; Ihloff, Ernie; McAllister, Brian; Milner, Richard; North, William; Tschalär, C; Tsentalovich, Evgeni; Wang, Defa; Wang, Dong; Wang, Fuhua; Zolfaghari, Abbasali; Zwart, Townsend; van der Laan, Jan

2005-01-01

The MIT Bates Accelerator Center is delivering highly polarized electron beams to its South Hall Ring for use in Nuclear Physics Experiments. Circulating electron currents in excess of 200 mA with polarization of 70% are scattered from a highly polarized, but very thin atomic beam source deuterium target. At the electron source a compact diode laser creates photoemission of quasi-CW mA pulses of polarized electrons at low duty factors from a strained GaAs photocathode. Refurbished RF transmitters provide power to the 2856 MHz linac, accelerating the beam to 850 MeV in two passes before injection into the South Hall Ring. In the ring a Siberian snake serves to maintain a high degree of longitudinal polarization at the BLAST scattering target. A Compton laser back-scattering polarimeter measures the electron beam polarization with a statistical acuracy of 6% every 15 minutes.

Vacuum nonlinear electrodynamic polarization effects in hard emission of pulsars and magnetars

Energy Technology Data Exchange (ETDEWEB)

Denisov, V.I.; Sokolov, V.A.; Svertilov, S.I., E-mail: vid.msu@yandex.ru, E-mail: sokolov.sev@inbox.ru, E-mail: sis@coronas.ru [Physics Department, Moscow State University, Moscow (Russian Federation)

2017-09-01

The nonlinear electrodynamics influence of pulsar magnetic field on the electromagnetic pulse polarization is discussed from the point of observation interpretation. The calculations of pulsar magnetic field impact on the electromagnetic pulse polarization are made in such a way to make it easier to interpret these effects in space experiments. The law of hard emission pulse propagation in the pulsar magnetic field according to the vacuum (nonlinear electrodynamics is obtained. It has been shown, that due to the birefringence in the vacuum the front part of any hard emission pulse coming from a pulsar should be linearly polarized and the rest of pulse can have arbitrary polarization. The observational possibilities of vacuum birefringence are discussed. In this paper we give the estimations of detector parameters such as effective area, exposure time and necessity of polarization measurements with high accuracy. The combination of large area and extremely long exposure time gives the good opportunity to search the fine polarization effects like vacuum nonlinear electrodynamics birefringence.

Soldered Contact and Current Risetime Effects on Negative Polarity Wire Array Z-pinches

International Nuclear Information System (INIS)

Chalenski, D. A.; Kusse, B. R.; Greenly, J. B.; Blesener, I. C.; McBride, R. D.; Hammer, D. A.; Knapp, P. F.

2009-01-01

and implosion phases. X-ray yield was increased with soldered arrays in negative polarity with long pulses. The bolometer also showed a 50% increase in radial power emitted for soldered arrays. 4-frame images showed soldered arrays have a more pronounced ''Christmas Tree'' effect originating from the cathode. The inductive voltage monitor showed, with both long and short pulses, that soldered and no-solder arrays reached the same minimum current radius at the same time. However, with long pulses soldered arrays radiate x-rays at the time of minimum current radius while no-solder array x-ray output is delayed by ∼20 ns, resulting in decreased x-ray yield.

A New Resonant Capacitor Diode Voltage Multiplier Topology for Pulsed Power Application

Directory of Open Access Journals (Sweden)

Mohammad Kebriaei

2017-09-01

Full Text Available Today, the pulsed power systems have been employed in many applications. To meet the requirement of user, the pulse generator should enjoy the advantages of compactness, high flexibility, high pulse repetition rate and cost efficiency. Among all of converters that can be used to generate high voltage pulses, capacitance diode voltage multiplier (CDVM is a good candidate to meet the mentioned requirements. In this paper a new converter that is combination of full-bridge inverter, CDVM and resonant circuit is proposed. The performance of developed converter is compared with the conventional circuits and is demonstrated via simulation in MATLAB/SIMULINK. Experimental tests on a prototype setup have verified the capability of this topology.

The neutrino horn 300 kiloampere pulsed power supply at Brookhaven National Laboratory

International Nuclear Information System (INIS)

Sandberg, J.; Smith, G.A.; Carroll, A.S.

1987-01-01

A 300 Kiloampere pulsed power system used to energize the Brookhaven focusing neutrino horn is described. The constant current switching section, coaxial power feed and low level control system are presented. Calculations determining system performance are compared with measured values. Plans for future systems are discussed

High-power pulsed light ion beams for applications in fusion- and matter research

International Nuclear Information System (INIS)

Bluhm, H.; Karow, H.U.; Rusch, D.; Zieher, K.W.

1982-01-01

The foundations of ultrahigh-power pulse techniques are described together with the two pulse generators KALIF (Karlsruhe Light lion Facility) and Pollux of the INR. The physical principles and diagnostics of ion beam production are discussed as well as possible applications in the field of fusion research. (orig./HT) [de

CrN/AlN nanolaminate coatings deposited via high power pulsed and middle frequency pulsed magnetron sputtering

International Nuclear Information System (INIS)

Bagcivan, N.; Bobzin, K.; Ludwig, A.; Grochla, D.; Brugnara, R.H.

2014-01-01

Nanolaminate coatings based on transition metal nitrides such as CrN, AlN and TiN deposited via physical vapor deposition (PVD) have shown great advantage as protective coatings on tools and components subject to high loads in tribological applications. By varying the individual layer materials and their thicknesses it is possible to optimize the coating properties, e.g. hardness, Young's modulus and thermal stability. One way for further improvement of coating properties is the use of advanced PVD technologies. High power pulsed magnetron sputtering (HPPMS) is an advancement of pulsed magnetron sputtering (MS). The use of HPPMS allows a better control of the energetic bombardment of the substrate due to the higher ionization degree of metallic species. It provides an opportunity to influence chemical and mechanical properties by varying the process parameters. The present work deals with the development of CrN/AlN nanolaminate coatings in an industrial scale unit by using two different PVD technologies. Therefore, HPPMS and mfMS (middle frequency magnetron sputtering) technologies were used. The bilayer period Λ, i.e. the thickness of a CrN/AlN double layer, was varied between 6.2 nm and 47.8 nm by varying the rotational speed of the substrate holders. In a second step the highest rotational speed was chosen and further HPPMS CrN/AlN coatings were deposited applying different HPPMS pulse lengths (40, 80, 200 μs) at the same mean cathode power and frequency. Thickness, morphology, roughness and phase composition of the coatings were analyzed by means of scanning electron microscopy (SEM), confocal laser microscopy, and X-ray diffraction (XRD), respectively. The chemical composition was determined using glow discharge optical emission spectroscopy (GDOES). Detailed characterization of the nanolaminate was conducted by transmission electron microscopy (TEM). The hardness and the Young's modulus were analyzed by nanoindentation measurements. The residual

Pulsed power driven hohlraum research at Sandia National Laboratories

International Nuclear Information System (INIS)

Leeper, R.J.; Alberts, T.E.; Allshouse, G.A.

1996-01-01

Three pulsed power driven hohlraum concepts are being investigated at Sandia for application to inertial fusion research. These hohlraums are driven by intense proton and Li ion beams as well as by two different types of z-pinch x-ray sources. Research on these hohlraum systems will continue on Sandia's PBFA II-Z facility

Possible applications of powerful pulsed CO2-Lasers in tokamak

International Nuclear Information System (INIS)

Nastoyashchii, A.F.; Morozov, I.N.; Hassanein, A.

1998-01-01

Applications of powerful pulsed CO 2 -lasers for injection of fuel tablets or creation of a protective screen from the vapor of light elements to protect against the destruction of plasma-facing components are discussed, and the corresponding laser parameters are determined. The possibility of using CO 2 -lasers in modelling the phenomena of powerful and energetic plasma fluxes interaction with a wall, as in the case of a plasma disruption, is considered. (author)

High-average-power 2 μm few-cycle optical parametric chirped pulse amplifier at 100 kHz repetition rate.

Science.gov (United States)

Shamir, Yariv; Rothhardt, Jan; Hädrich, Steffen; Demmler, Stefan; Tschernajew, Maxim; Limpert, Jens; Tünnermann, Andreas

2015-12-01

Sources of long wavelengths few-cycle high repetition rate pulses are becoming increasingly important for a plethora of applications, e.g., in high-field physics. Here, we report on the realization of a tunable optical parametric chirped pulse amplifier at 100 kHz repetition rate. At a central wavelength of 2 μm, the system delivered 33 fs pulses and a 6 W average power corresponding to 60 μJ pulse energy with gigawatt-level peak powers. Idler absorption and its crystal heating is experimentally investigated for a BBO. Strategies for further power scaling to several tens of watts of average power are discussed.

Operation and technology of high pulsed power generators

International Nuclear Information System (INIS)

Eyl, P.; Romary, P.

1995-01-01

In order to satisfy the needs of ''components and electronic circuits hardness'', a range of high pulsed power generators is available in the French Atomic Energy Commission. The goal of this paper is to present the general principles of operation and the main characteristics of the irradiation facilities which are operational at the CESTA center. Finally, we give a brief outline of the new technology developments. (authors). 6 refs., 16 figs

Dynamic modelling of balance of plant systems for a pulsed DEMO power plant

Energy Technology Data Exchange (ETDEWEB)

Harrington, C., E-mail: Chris.Harrington@ccfe.ac.uk

2015-10-15

Highlights: • A fully dynamic model of the balance of plant systems for pulsed DEMO is presented. • An operating strategy for handling pulse/dwell transitions has been devised. • Operation of a water-cooled system without energy storage appears feasible. • Steam turbine cycling can be minimised if rotation speed is maintained. - Abstract: The current baseline concept for a European DEMO defines a pulsed reactor producing power for periods of 2–4 h at a time, interrupted by dwell periods of approximately half an hour, potentially leading to cyclic fatigue of the heat transfer system and power generation equipment. Thermal energy storage systems could mitigate pulsing issues; however, the requirements for such a system cannot be defined without first understanding the challenges for pulsed operation, while any system will simultaneously increase the cost and complexity of the balance of plant. This work therefore presents a dynamic model of the primary heat transfer system and associated steam plant for a water-cooled DEMO, without energy storage, capable of simulating pulsed plant operation. An operating regime is defined such that the primary coolant flows continuously throughout the dwell period while the secondary steam flow is reduced. Simulation results show minimised thermal and pressure transients in the primary circuit, and small thermally induced stresses on the steam turbine rotor. If the turbine can be kept spinning to also minimise mechanical cycling, pulsed operation of a water-cooled DEMO without thermal energy storage may be feasible.

Long Pulse EBW Start-up Experiments in MAST

Directory of Open Access Journals (Sweden)

Shevchenko V.F.

2015-01-01

Full Text Available Start-up technique reported here relies on a double mode conversion (MC for electron Bernstein wave (EBW excitation. It consists of MC of the ordinary (O mode, entering the plasma from the low field side of the tokamak, into the extraordinary (X mode at a mirror-polarizer located at the high field side. The X mode propagates back to the plasma, passes through electron cyclotron resonance (ECR and experiences a subsequent X to EBW MC near the upper hybrid resonance (UHR. Finally the excited EBW mode is totally absorbed at the Doppler shifted ECR. The absorption of EBW remains high even in cold rarefied plasmas. Furthermore, EBW can generate significant plasma current giving the prospect of a fully solenoid-free plasma start-up. First experiments using this scheme were carried out on MAST [1]. Plasma currents up to 33 kA have been achieved using 28 GHz 100kW 90ms RF pulses. Recently experimental results were extended to longer RF pulses showing further increase of plasma currents generated by RF power alone. A record current of 73kA has been achieved with 450ms RF pulse of similar power. The current drive enhancement was mainly achieved due to RF pulse extension and further optimisation of the start-up scenario.

Pulse plating

CERN Document Server

Hansal, Wolfgang E G; Green, Todd; Leisner, Peter; Reichenbach, Andreas

2012-01-01

The electrodeposition of metals using pulsed current has achieved practical importance in recent years. Although it has long been known that changes in potential, with or without polarity reversal, can significantly affect the deposition process, the practical application of this has been slow to be adopted. This can largely be explained in terms of the complex relationship between the current regime and its effect on the electrodeposition process. In order to harness these effects, an understanding of the anodic and cathodic electrochemical processes is necessary, together with the effects of polarity reversal and the rate of such reversals. In this new monograph, the basics of metal electrodeposition from solution are laid out in great detail in seven distinct chapters. With this knowledge, the reader is able to predict how a given pulse train profile can be adopted to achieve a desired outcome. Equally important is the choice of a suitable rectifier and the ancillary control circuits to enable pulse platin...

New solid state opening switches for repetitive pulsed power technology

Energy Technology Data Exchange (ETDEWEB)

Lyubutin, S K; Mesyats, G A; Rukin, S N; Slovikovskii, B G; Turov, A M [Russian Academy of Sciences, Ekaterinburg (Russian Federation). Inst. of Electrophysics

1997-12-31

In 1991 the authors discovered a semiconductor opening switch (SOS) effect that occurs in p{sup +}-p-n-n{sup +} silicon structures at a current density of up to 60 kA/cm{sup 2}. This effect was used to develop high-power semiconductor opening switches in intermediate inductive storage circuits. The breaking power of the opening switches was as high as 5 GW, the interrupted current being up to 45 kA, reverse voltage up to 1 MV and the current interruption time between 10 and 60 ns. The opening switches were assembled from quantity-produced Russian-made rectifying diodes type SDL with hard recovery characteristic. On the basis of experimental and theoretical investigations of the SOS effect, new SOS diodes were designed and manufactured by the Electrophysical Institute. The paper gives basic parameters of the SOS diodes. The new diodes offer higher values of interrupted current and shorter times of current interruption together with a considerable increase in the energy switching efficiency. The new SOS diodes were used to develop repetitive all-solid-state pulsed generators with an output voltage of up to 250 kV, pulse repetition rate up to 5 kHz, and pulse duration between 10 and 30 ns. (author). 2 tabs., 3 figs., 4 refs.

Reduction of the pace polarization artefact for capture detection applications by a tri-phasic stimulation pulse.

Science.gov (United States)

Sutton, R; Fröhlig, G; de Voogt, W G; Goethals, M; Hintringer, F; Kennergren, C; Scanu, P; Guilleman, D; Treese, N; Hartung, W M; Stammwitz, E; Muetstege, A

2004-11-01

This study investigated the ability to minimize pace polarization artefacts (PPA) by adjusting the post-stimulus pulse duration of a tri-phasic stimulation pulse. Adjustment of the stimulation pulse was enabled by downloading special study software into an already implanted pacemaker. Tests were performed in a total of 296 atrial leads and 311 ventricular leads. Both chronic and acute leads were included in the study. Statistically significant differences were found in the initial PPA (without any adjustment of the stimulus pulse) between atrial and ventricular leads. In addition, significant differences were observed among various lead models with respect to changes over time in the initial ventricular PPA. Successful PPA reduction was defined as a reduction of the PPA below 0.5 mV for atrial leads and below 1 mV for ventricular leads. Results show a success rate for ventricular and atrial PPA reduction of 97.8% and 98.7%, respectively. Threshold tests showed that after reduction of the PPA loss of ventricular capture can be reliably detected. However, atrial threshold tests showed many false positive evoked response detections. In addition, unexpectedly high evoked response amplitudes were observed in the atrium after reduction of the PPA. Results from additional measurements suggest that these high atrial evoked response amplitudes come from the influence of the input filter of the pacemaker.

Proposed method to produce a highly polarized e+ beam for future linear colliders

International Nuclear Information System (INIS)

Okugi, Toshiyuki; Chiba, Masami; Kurihara, Yoshimasa

1996-01-01

We propose a method to produce a spin-polarized e + beam using e + e - pair-creation by circularly polarized photons. Assuming Compton scattering of an unpolarized e - beam and circularly polarized laser light, scattered γ-rays at the high end of the energy spectrum are also circularly polarized. If those γ-rays are utilized to create e ± pairs on a thin target, the spin-polarization is preserved for e + 's at the high end of their energy spectrum. By using the injector linac of Accelerator Test Facility at KEK and a commercially available Nd:YAG pulse laser, we can expect about 10 5 polarized e + 's per second with a degree of polarization of 80% and a kinetic energy of 35-80 MeV. The apparatus for creation and measurement of polarized e + 's is being constructed. We present new idea for possible application of our method to future linear colliders by utilizing a high-power CO 2 laser. (author)

Photovoltaic High-Frequency Pulse Charger for Lead-Acid Battery under Maximum Power Point Tracking

Directory of Open Access Journals (Sweden)

Hung-I. Hsieh

2013-01-01

Full Text Available A photovoltaic pulse charger (PV-PC using high-frequency pulse train for charging lead-acid battery (LAB is proposed not only to explore the charging behavior with maximum power point tracking (MPPT but also to delay sulfating crystallization on the electrode pores of the LAB to prolong the battery life, which is achieved due to a brief pulse break between adjacent pulses that refreshes the discharging of LAB. Maximum energy transfer between the PV module and a boost current converter (BCC is modeled to maximize the charging energy for LAB under different solar insolation. A duty control, guided by a power-increment-aided incremental-conductance MPPT (PI-INC MPPT, is implemented to the BCC that operates at maximum power point (MPP against the random insolation. A 250 W PV-PC system for charging a four-in-series LAB (48 Vdc is examined. The charging behavior of the PV-PC system in comparison with that of CC-CV charger is studied. Four scenarios of charging statuses of PV-BC system under different solar insolation changes are investigated and compared with that using INC MPPT.

Ionization of oriented targets by intense circularly polarized laser pulses: Imprints of orbital angular nodes in the two-dimensional momentum distribution

DEFF Research Database (Denmark)

Martiny, Christian; Abu-Samha, Mahmoud; Madsen, Lars Bojer

2010-01-01

We solve the three-dimensional time-dependent Schrödinger equation for a few-cycle circularly polarized femtosecond laser pulse that interacts with an oriented target exemplified by an argon atom, initially in a 3px or 3py state. The photoelectron momentum distributions show distinct signatures o...

Simultaneous Wireless Power Transfer and Data Communication Using Synchronous Pulse-Controlled Load Modulation.

Science.gov (United States)

Mao, Shitong; Wang, Hao; Zhu, Chunbo; Mao, Zhi-Hong; Sun, Mingui

2017-10-01

Wireless Power Transfer (WPT) and wireless data communication are both important problems of research with various applications, especially in medicine. However, these two problems are usually studied separately. In this work, we present a joint study of both problems. Most medical electronic devices, such as smart implants, must have both a power supply to allow continuous operation and a communication link to pass information. Traditionally, separate wireless channels for power transfer and communication are utilized, which complicate the system structure, increase power consumption and make device miniaturization difficult. A more effective approach is to use a single wireless link with both functions of delivering power and passing information. We present a design of such a wireless link in which power and data travel in opposite directions. In order to aggressively miniaturize the implant and reduce power consumption, we eliminate the traditional multi-bit Analog-to-Digital Converter (ADC), digital memory and data transmission circuits all together. Instead, we use a pulse stream, which is obtained from the original biological signal, by a sigma-delta converter and an edge detector, to alter the load properties of the WPT channel. The resulting WPT signal is synchronized with the load changes therefore requiring no memory elements to record inter-pulse intervals. We take advantage of the high sensitivity of the resonant WPT to the load change, and the system dynamic response is used to transfer each pulse. The transient time of the WPT system is analyzed using the coupling mode theory (CMT). Our experimental results show that the memoryless approach works well for both power delivery and data transmission, providing a new wireless platform for the design of future miniaturized medical implants.

Higher-order power harmonics of pulsed electrical stimulation modulates corticospinal contribution of peripheral nerve stimulation.

Science.gov (United States)

Chen, Chiun-Fan; Bikson, Marom; Chou, Li-Wei; Shan, Chunlei; Khadka, Niranjan; Chen, Wen-Shiang; Fregni, Felipe

2017-03-03

It is well established that electrical-stimulation frequency is crucial to determining the scale of induced neuromodulation, particularly when attempting to modulate corticospinal excitability. However, the modulatory effects of stimulation frequency are not only determined by its absolute value but also by other parameters such as power at harmonics. The stimulus pulse shape further influences parameters such as excitation threshold and fiber selectivity. The explicit role of the power in these harmonics in determining the outcome of stimulation has not previously been analyzed. In this study, we adopted an animal model of peripheral electrical stimulation that includes an amplitude-adapted pulse train which induces force enhancements with a corticospinal contribution. We report that the electrical-stimulation-induced force enhancements were correlated with the amplitude of stimulation power harmonics during the amplitude-adapted pulse train. In an exploratory analysis, different levels of correlation were observed between force enhancement and power harmonics of 20-80 Hz (r = 0.4247, p = 0.0243), 100-180 Hz (r = 0.5894, p = 0.0001), 200-280 Hz (r = 0.7002, p harmonics. This is a pilot, but important first demonstration that power at high order harmonics in the frequency spectrum of electrical stimulation pulses may contribute to neuromodulation, thus warrant explicit attention in therapy design and analysis.

Dispersion measurement on chirped mirrors at arbitrary incidence angle and polarization state (Conference Presentation)

Science.gov (United States)

Kovacs, Mate; Somoskoi, Tamas; Seres, Imre; Borzsonyi, Adam; Sipos, Aron; Osvay, Károly

2017-05-01

The optical elements of femtosecond high peak power lasers have to fulfill more and more strict requirements in order to support pulses with high intensity and broad spectrum. In most cases chirped pulse amplification scheme is used to generate high peak power ultrashort laser pulses, where a very precise control of spectral intensity and spectral phase is required in reaching transform-limited temporal shape at the output. In the case of few cycle regime, the conventional bulk glass, prism-, grating- and their combination based compressors are not sufficient anymore, due to undesirable nonlinear effects in their material and proneness to optical damages. The chirped mirrors are also commonly used to complete the compression after a beam transport system just before the target. Moreover, the manufacturing technology requires quality checks right after production and over the lifetime of the mirror as well, since undesired deposition on the surface can lead alteration from the designed value over a large part of the aperture. For the high harmonic generation, polarization gating technology is used to generate single attosecond pulses [1]. In this case the pulse to be compressed has various polarization state falling to the chirped mirrors. For this reason, it is crucial to measure the dispersion of the mirrors for the different polarization states. In this presentation we demonstrate a simple technique to measure the dispersion of arbitrary mirror at angles of incidence from 0 to 55 degree, even for a 12" optics. A large aperture 4" mirror has been scanned over with micrometer accuracy and the dispersion property through the surface has been investigated with a stable interference fringes in that robust geometry. We used Spectrally Resolved Interferometry, which is based on a Michaelson interferometer and a combined visible and infrared spectrometer. Tungsten halogen lamp with 10 mW coupled optical power was used as a white-light source so with the selected

Pulse-width modulated DC-DC power converters

CERN Document Server

Kazimierczuk, Marian K

2008-01-01