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Sample records for amp beam currents

  1. CMOS technology and current-feedback op-amps

    DEFF Research Database (Denmark)

    Bruun, Erik

    1993-01-01

    solutions providing improved input characteristics are presented. Problems related to the achievable output voltage swing are examined, and circuits which may be used to achieve a near rail to rail output swing are proposed. It is concluded that mere translations of bipolar circuit designs yield a rather......Some of the problems related to the application of CMOS technology to current-feedback operational amplifiers (CFB op-amps) are identified. Problems caused by the low device transconductance and by the absence of matching between p-channel and n-channel transistors are examined, and circuit...

  2. LEDA beam diagnostics instrumentation: Beam current measurement

    International Nuclear Information System (INIS)

    The Low Energy Demonstration Accelerator (LEDA) facility located at Los Alamos National Laboratory (LANL) accelerates protons to an energy of 6.7 MeV and current of 100 mA operating in either a pulsed or cw mode. Two types of current measurements are used. The first is an AC or pulsed-current measurement which uses three LANL built toroids. They are placed in the beamline in such a way as to measure important transmission parameters and act as a differential current-loss machine protection system. The second system is a DC current measurement used to measure cw beam characteristics and uses toroids from Bergoz Inc. There are two of these systems, so they can also be used for transmission measurements. The AC system uses custom processing electronics whereas the DC system uses a modified Bergoz registered electronics system. Both systems feature data acquisition via a series of custom TMS320C40 Digital Signal Processing (DSP) boards. Of special interest to this paper is the operation of these systems, the calibration technique, the differential current loss measurements and fast-protection processing, current droop characteristics for the AC system, and existing system noise levels. This paper will also cover the DSP system operations and their interaction with the main accelerator control system

  3. Nondestructive synchronous beam current monitor

    International Nuclear Information System (INIS)

    A fast current transformer is mounted after the deflectors of the Berkeley 88-Inch Cyclotron. The measured signal is amplified and connected to the input of a lock-in amplifier. The lock-in amplifier performs a synchronous detection of the signal at the cyclotron second harmonic frequency. The magnitude of the signal detected is calibrated against a Faraday cup and corresponds to the beam intensity. It has exceptional resolution, long term stability, and can measure the beam current leaving the cyclotron as low as 1 nA

  4. Digitally compensated beam current transformer

    CERN Document Server

    Kesselman, Martin

    2005-01-01

    The Spallation Neutron Source (SNS) is being built by a collaboration of six laboratories. Beam current monitors (BCMs) will be used to record the current of H-minus and H-plus beams ranging from 15 mA (tune-up in the Front End and Linac) to over 60A fully accumulated in the Ring and dumped to the load as a single pulse in the Ring to Beam Target (RTBT). The time structure of these beams ranges from 645ns "mini" bunches at the 1.05 MHz ring revolution rate, to an overall 1 ms long macro-pulse. The requirements for the BCMs will depend upon their location within the system. The need to measure individual mini-pulses, examine the characteristics of the chopper edge, as well as the longer average current pulse of the macropulse, or long duration pulses during Linac tuning place wide requirements upon the response of current transformers. To obtain the desired accuracy and resolution, current transformers must have less than 1 ns rise time and droops of 0.1 %/ms. This places a significant design burden on the cur...

  5. Beam current measurement and beam positioning for baby-ebm

    International Nuclear Information System (INIS)

    This paper describes the electron beam detection of Baby EBM. The detection is divided by two categories; beam current measurement and beam positioning under the scanning window. The beam detector system was completely fabricated and tested and the detector was able to detect the electron beam of Baby EBM. It has been found that the beam current of this EBM is 1.62 mA for energy of 0.14 MeV. A higher beam current can be obtained if a proper cooling system to the window foil is installed. (Author)

  6. High current beam transport with multiple beam arrays

    International Nuclear Information System (INIS)

    Highlights of recent experimental and theoretical research progress on the high current beam transport of single and multiple beams by the Heavy Ion Fusion Accelerator Research (HIFAR) group at the Lawrence Berkeley Laboratory (LBL) are presented. In the single beam transport experiment (SBTE), stability boundaries and the emittance growth of a space charge dominated beam in a long quadrupole transport channel were measured and compared with theory and computer simulations. Also, a multiple beam ion induction linac (MBE-4) is being constructed at LBL which will permit study of multiple beam transport arrays, and acceleration and bunch length compression of individually focused beamlets. Various design considerations of MBE-4 regarding scaling laws, nonlinear effects, misalignments, and transverse and longitudinal space charge effects are summarized. Some aspects of longitudinal beam dynamics including schemes to generate the accelerating voltage waveforms and to amplify beam current are also discussed

  7. Laser diagnostic for high current H- beams

    International Nuclear Information System (INIS)

    In the last 5 years, significant technology advances have been made in the performance, size, and cost of solid-state diode-pumped lasers. These developments enable the use of compact Q-switched Nd:YAG lasers as a beam diagnostic for high current H- beams. Because the threshold for photodetachment is only 0.75 eV, and the maximum detachment cross section is 4x10-17cm2 at 1.5 eV, A 50 mJ/pulse Q-switched Nd:YAG laser can neutralize a significant fraction of the beam in a single 10 ns wide pulse. The neutral beam maintains nearly identical parameters as the parent H- beam, including size, divergence, energy, energy spread, and phase spread. A dipole magnet can separate the neutral beam from the H- beam to allow diagnostics on the neutral beam without intercepting the high-current H- beam. Such a laser system can also be used to extract a low current proton beam, or to induce fluorescence in partially stripped heavy ion beams. Possible beamline diagnostic systems will be reviewed, and the neutral beam yields will be calculated. copyright 1998 American Institute of Physics

  8. Effect of cAMP on short-circuit current in isolated human ciliary body

    Institute of Scientific and Technical Information of China (English)

    WU Ren-yi; MA Ning; HU Qian-qian

    2013-01-01

    Background Cyclic adenosine monophosphate (cAMP) could activate chloride channels in bovine ciliary body and trigger an increase in the ionic current (short-circuit current,Isc) across the ciliary processes in pigs.The purpose of this study was to investigate how cAMP modulates Isc in isolated human ciliary processes and the possible involvement of chloride transport across the tissue in cAMP-induced Isc change.Methods In an Ussing-type chamber system,the Isc changes induced by the cAMP analogue 8-bromo-cAMP and an adenylyl cyclase activator forskolin in isolated human ciliary processes were assessed.The involvement of Cl-component in the bath solution was investigated.The effect of Cl-channel (10 μmol/L niflumic acid and 1 mmol/L 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid (DIDS)),K+ channel (10 mmol/L tetraethylammonium chloride (TEA)),or Na+ channel blockers (1 mmol/L amiloride) on 8-bromo-cAMP-induced Isc change was also studied.Results Dose-dependently,8-bromo-cAMP (10 nmol/L-30 μmol/L) or forskolin (10 nmol/L-3 μmol/L) increased Isc across the ciliary processes with an increase in negative potential difference on the non-pigmented epithelium (NPE) side of the tissue.Isc increase induced by 8-bromo-cAMP was more pronounced when the drug was applied on the NPE side than on the pigmented epithelium side.When the tissue was bathed in low Cl-solutions,the Isc increase was significantly inhibited.Finally,niflumic acid and DIDS,but not TEA or amiloride,significantly prevented the Isc increase induced by 8-bromo-cAMP.Conclusions cAMP stimulates stroma-to-aqueous anionic transport in isolated human ciliary processes.Chloride is likely to be among the ions,the transportation of which across the tissue is triggered by cAMP,suggesting the potential role of cAMP in the process of aqueous humor formation in human eyes.

  9. A LVDT conditioner for the beam profile monitors of the AmPS

    International Nuclear Information System (INIS)

    A LVDT (Linear Variable Differential Transformer) is a transducer for localization. Because of its applied materials, its construction and the absence of bearings etc. the instrument is suitable to be applied in locations where radioactive radiation is present. In order to obtain information about the position of the iron core in the transducer, a conditioner is needed. In 1977 by Digel a conditioner has been developed for the beam profile monitors (moving wire) of MEA because the 'market' could not meet the requirements then. Nowadays the 'market' offers i.c.'s which can take over the work of the Eurocard developed then. Digel has investigated them in order to see if they are applicable for the beam profile monitors of AmPS. (author). 5 refs.; 7 figs.; 13 tabs

  10. Power threshold for neutral beam current drive

    International Nuclear Information System (INIS)

    For fully noninductive current drive in tokamaks using neutral beams, there is a power and density threshold condition, setting a minimum value for P3/2/n2. If this condition is not met, stationary state cannot occur, and a tokamak discharge will collapse. This is a consequence of the coupling between current and electron temperature, or between current drive efficiency and energy confinement time. 4 figs

  11. Achromatic beam transport of High Current Injector

    Science.gov (United States)

    Kumar, Sarvesh; Mandal, A.

    2016-02-01

    The high current injector (HCI) provides intense ion beams of high charge state using a high temperature superconducting ECR ion source. The ion beam is accelerated upto a final energy of 1.8 MeV/u due to an electrostatic potential, a radio frequency quadrupole (RFQ) and a drift tube linac (DTL). The ion beam has to be transported to superconducting LINAC which is around 50 m away from DTL. This section is termed as high energy beam transport section (HEBT) and is used to match the beam both in transverse and longitudinal phase space to the entrance of LINAC. The HEBT section is made up of four 90 deg. achromatic bends and interconnecting magnetic quadrupole triplets. Two RF bunchers have been used for longitudinal phase matching to the LINAC. The ion optical design of HEBT section has been simulated using different beam dynamics codes like TRACEWIN, GICOSY and TRACE 3D. The field computation code OPERA 3D has been utilized for hardware design of all the magnets. All the dipole and quadrupole magnets have been field mapped and their test results such as edge angles measurements, homogeneity and harmonic analysis etc. are reported. The whole design of HEBT section has been performed such that the most of the beam optical components share same hardware design and there is ample space for beam diagnostics as per geometry of the building. Many combination of achromatic bends have been simulated to transport the beam in HEBT section but finally the four 90 deg. achromatic bend configuration is found to be the best satisfying all the geometrical constraints with simplified beam tuning process in real time.

  12. Charged particle beam current monitoring tutorial

    International Nuclear Information System (INIS)

    A tutorial presentation is made on topics related to the measurement of charged particle beam currents. The fundamental physics of electricity and magnetism pertinent to the problem is reviewed. The physics is presented with a stress on its interpretation from an electrical circuit theory point of view. The operation of devices including video pulse current transformers, direct current transformers, and gigahertz bandwidth wall current style transformers is described. Design examples are given for each of these types of devices. Sensitivity, frequency response, and physical environment are typical parameters which influence the design of these instruments in any particular application. Practical engineering considerations, potential pitfalls, and performance limitations are discussed

  13. Microstructure cantilever beam for current measurement

    Directory of Open Access Journals (Sweden)

    M.T.E. Khan

    2010-01-01

    Full Text Available Most microelectromechanical systems (MEMS sensors are based on the microcantilever technology, which uses a broad range of design materials and structures. The benefit ofMEMStechnology is in developing devices with a lower cost, lower power consumption, higher performance and greater integration. A free-end cantilever beam with a magnetic material mass has been designed using MEMS software tools. The magnetic material was used to improve the sensitivity of the cantilever beam to an externally-applied magnetic field. The cantilever was designed to form a capacitance transducer, which consisted of variable capacitance where electrical and mechanical energies were exchanged. The aim of this paper was to analyse the system design of the microcantilever when subjected to a magnetic field produced by a current-carrying conductor. When the signal, a sinusoidal current with a constant frequency, was applied, the cantilever beam exhibited a vibration motion along the vertical axis when placed closer to the line current. This motion created corresponding capacitance changes and generated a voltage output proportional to the capacitive change in the signal-processing circuitry attached to the microcantilever. The equivalent massspring system theory was used to describe and analyse the effect of the natural frequency of the system vibrations and motion due to the applied magnetic field, in a single-degree of freedom. The main application of this microcantilever is in current measurements to develop a non-contact current sensor mote.

  14. High Current Beam Transport to SIS18

    CERN Document Server

    Richter, S; Dahl, L; Glatz, J; Groening, L; Yaramishev, S

    2004-01-01

    The optimized transversal and longitudinal matching of space charged dominated ion beams to SIS18 is essential for a loss free injection. This paper focuses on the beam dynamics in the transfer line (TK) from the post-stripper accelerator to the SIS18. Transverse beam emittance measurements at different positions along the TK were done. Especially, the different foil stripping modes were investigated. A longitudinal emittance measurement set-up was commissioned at the entry to the TK. It is used extensively to tune all the rebunchers along the UNILAC. An addition, a test bench is in use for measurements of longitudinal bunch profiles, which enables to monitor for the final debunching to SIS18. Multi particle simulations by means of PARMILA allow a detailed analysis of experimental results for different ion currents.

  15. Current status of the LBNE neutrino beam

    CERN Document Server

    Moore, Craig Damon; Crowley, Cory Francis; Hurh, Patrick; Hylen, James; Lundberg, Byron; Marchionni, Alberto; McGee, Mike; Mokhov, Nikolai V; Papadimitriou, Vaia; Plunkett, Rob; Reitzner, Sarah Diane; Stefanik, Andrew M; Velev, Gueorgui; Williams, Karlton; Zwaska, Robert Miles

    2015-01-01

    The Long Baseline Neutrino Experiment (LBNE) will utilize a neutrino beamline facility located at Fermilab. The facility is designed to aim a beam of neutrinos toward a detector placed in South Dakota. The neutrinos are produced in a three-step process. First, protons from the Main Injector hit a solid target and produce mesons. Then, the charged mesons are focused by a set of focusing horns into the decay pipe, towards the far detector. Finally, the mesons that enter the decay pipe decay into neutrinos. The parameters of the facility were determined by an amalgam of the physics goals, the Monte Carlo modeling of the facility, and the experience gained by operating the NuMI facility at Fermilab. The initial beam power is expected to be ~700 kW, however some of the parameters were chosen to be able to deal with a beam power of 2.3 MW. The LBNE Neutrino Beam has made significant changes to the initial design through consideration of numerous Value Engineering proposals and the current design is described.

  16. Effects of AMP579 and adenosine on L-type Ca2+ current in isolated rat ventricular myocytes

    Institute of Scientific and Technical Information of China (English)

    Xiong WANG; Bo-wei WU; Dong-mei WU

    2005-01-01

    Aim: To compare the effects of AMP579 and adenosine on L-type Ca2+ current (ICa- L) in rat ventricular myocytes and explore the mechanism by which AMP579 acts on ICa-L. Methods: ICa-L was recorded by patch-clamp technique in whole-cell configuration. Results: Adenosine (10 nmol/L to 50 μmol/L) showed no effect on basal ICa- L, but it inhibited the ICa-L induced by isoproterenol 10 nmol/L in a concen tration-dependent manner with the IC50 of 13.06 μmol/L. Similar to adenosine,AMP579 also showed an inhibitory effect on the ICa-L induced by isoproterenol.AMP579 and adenosine (both in 10 μmol/L) suppressed isoproterenol-induced ICa-L by 11.1% and 5.2%, respectively. In addition, AMP579 had a direct inhibitory effect on basal ICa-L in a concentration-dependent manner with IC50 (1.17 μmol/L).PD116948 (30 μmol/L), an adenosine A1 receptor blocker, showed no action on the inhibitory effect of AMP579 on basal ICa-L. However, GF109203X (0.4 μmol/L), a special protein kinase C (PKC) blocker, could abolish the inhibitory effect of AMP579 on basal ICa-L. So the inhibitory effect of AMP579 on basal ICa-L was induced through activating PKC, but not linked to adenosine A1 receptor. Conclusion:AMP579 shows a stronger inhibitory effect than adenosine on the ICa-L induced by isoproterenol. AMP579 also has a strong inhibitory effect on basal ICa-L in rat ventricular myocytes. Activation of PKC is involved in the inhibitory effect of AMP579 on basal ICa-L at downstream-mechanism.

  17. Design principles for high current beam injection lines

    International Nuclear Information System (INIS)

    We discuss the design principles for high current injection beam lines having a high degree of beam quality preservation. These principles are applied to designing a high current e-beam injection line delivering 10 MeV e-beams from the injector to an accelerator driving LTV FELs, as proposed at CEBAF

  18. Pushing beam currents to the limit

    International Nuclear Information System (INIS)

    One of the cyclotron systems running at the Nordion Int. radioisotope production facility at TRIUMF is the EBCO TR30. This cyclotron produces up to 250μA on each of two beamlines simultaneously. Two solid (for the production of 201Tl, 57Co, 67Ga and 111In) and a gaseous (for producing 123I) target station are in routine operation on this facility. Since future projections indicate a greater demand for reliable radioisotope production there is a program underway to increase the output of the facility to double the present level. One way that this is being achieved is through a careful thermal analysis of the the solid target system to maximize its performance. In conjunction with this we have developed and tested a 500μA upgrade of our solid target system. Gas targets are being investigated for possible ways of increasing the efficiency of production via rotating/sweeping beams which allow higher beam currents. Finally, the TR30 cyclotron is being upgraded to deliver 50-100% more beam on target. By pushing both the cyclotron and target technology to the limit we will be able to produce significantly higher levels of radioisotopes than many other comparable facilities. (author) 11 refs., 3 figs

  19. Beam-driven and bootstrap currents in JT-60 upgrade

    International Nuclear Information System (INIS)

    We recently performed beam-driven current-drive experiments with a low fraction of bootstrap currents in a wide range of plasma parameters in JT-60 upgrade. The evidence of current profile modification by the beam-driven current with tangential neutral beam injectors. A high βN, high βp and ELMy H-mode plasma with possibly fully non-inductive current-drive by beam-driven and bootstrap currents was maintained for a considerably long duration with the combined injection of quasi-perpendicular and co-tangential beams. (author) 4 refs., 7 figs

  20. NRSF causes cAMP-sensitive suppression of sodium current in cultured hippocampal neurons

    Science.gov (United States)

    Nadeau, H.; Lester, H. A.

    2002-01-01

    The neuron restrictive silencer factor (NRSF/REST) has been shown to bind to the promoters of many neuron-specific genes and is able to suppress transcription of Na(+) channels in PC12 cells, although its functional effect in terminally differentiated neurons is unknown. We constructed lentiviral vectors to express NRSF as a bicistronic message with green fluorescent protein (GFP) and followed infected hippocampal neurons in culture over a period of 1-2 wk. NRSF-expressing neurons showed a time-dependent suppression of Na(+) channel function as measured by whole cell electrophysiology. Suppression was reversed or prevented by the addition of membrane-permeable cAMP analogues and enhanced by cAMP antagonists but not affected by increasing protein expression with a viral enhancer. Secondary effects, including altered sensitivity to glutamate and GABA and reduced outward K(+) currents, were duplicated by culturing GFP-infected control neurons in TTX. The striking similarity of the phenotypes makes NRSF potentially useful as a genetic "silencer" and also suggests avenues of further exploration that may elucidate the transcription factor's in vivo role in neuronal plasticity.

  1. Two-Dimensional Hybrid Model for High-Current Electron Beam Transport in a Dense Plasma

    Institute of Scientific and Technical Information of China (English)

    CAO Lihua; WANG Huan; ZHANG Hua; LIU Zhanjun; WU Junfeng; LI Baiwen

    2014-01-01

    A two-dimensional hybrid code is developed to model the transport of a high-current electron beam in a dense plasma target.The beam electrons are treated as particles and described by particle-in-cell simulation including collisions with the target plasma particles.The background target plasma is assumed to be a stationary fluid with temperature variations.The return current and the self-generated electric and magnetic fields are obtained by combining Ampère's law without the displacement current,the resistive Ohm's law and Faraday's law.The equations are solved in two-dimensional cylindrical geometry with rotational symmetry on a regular grid,with centered spatial differencing and first-order implicit time differencing.The algorithms implemented in the code are described,and a numerical experiment is performed for an electron beam with Maxwellian distribution ejected into a uniform deuterium-tritium plasma target.

  2. Bootstrap current of fast ions in neutral beam injection heating

    International Nuclear Information System (INIS)

    The bootstrap current of fast ions produced by the neutral beam injection is investigated in a large aspect ratio tokamak with circular cross-section under specific parameters. The bootstrap current density distribution and the total bootstrap current are figured out. In addition, the beam bootstrap current always accompanies the electron return current due to the parallel momentum transfer from fast ions. With the electron return current considered, the net current density obviously decreases due to electron return current, at the same time the peak of current moves towards the centre plasma. Numerical results show that the value of the net current depends sensitively not only on the angle of the neutral beam injection but also on the ratio of the velocity of fast ions to the critical velocity: the value of net current is small for the neutral beam parallel injection but increases multipliedly for perpendicular injection, and increases with beam energy increasing. (authors)

  3. Design and development of low current measurement electronics for beam diagnostics system

    International Nuclear Information System (INIS)

    Beam diagnostics devices are essential constituents of any particle accelerator. In many beam diagnostics devices such as wire beam profile monitor (wire-BPM), Faraday cup etc., low current signal processing and measurement is carried out. In this paper low current measurement using a trans-impedance amplifier, based on T-network topology of feedback resistors is presented. This technique employs a T-network of relatively lower value resistors in the feedback path of op-amp to achieve high gain without requiring high value resistors which have associated leakage problems. The designed low current signal processing electronics based on this technique can linearly measure current signal in the rage of 100pA to 1μA, To accommodate wide range of current measurement, four selectable gains of trans-impedance amplifier have been incorporated in the circuit. The microcontroller based processing electronics monitors the real time low current signal, then automatically switches the appropriate gain to match the input current for its accurate measurement. It has been tested and calibrated successfully in lab with standard low current source. The processing electronics has also been tested and verified for current signal measurement of a wire-BPM installed at the visible diagnostic beam line (BL-24) of Indus-2, synchrotron light source at RRCAT, Indore. (author)

  4. Solar wind double ions beams and the heliospheric current sheet

    Science.gov (United States)

    Hammond, C. M.; Feldman, W. C.; Phillips, J. L.; Goldstein, B. E.; Balogh, A.

    1995-01-01

    Double ion beams are often observed in the solar wind, but little work has been done in relating these beams to structures within the solar wind. Double ion beams are observed as beams of a given ion species and charge state occurring at two different energies. We use the three-dimensional ion plasma instrument on board the Ulysses spacecraft to look for evidence of such beams associated with the heliospheric current sheet. In a subset chosen independently of plasma parameters consisting of 8 of cover 47 crossings of the current sheet made during the inecliptic phase of the Ulysses mission we find that these double ion beams are always present on either side of the current sheet. The double beams are present in both the proton and helium species. The secondary beam typically has a higher helium abundance, which suggests that these beams are formed in the helium-rich corona rather than in interplanetary space. The double beams are not present in the interior of the current sheet. Neither collisions nor effects of plasma beta can account for the disappearance of the double beams inside the current sheet in all eight cases. We postulate that these beams are formed by reconnection occurring near the Sun in the boundary region between the open field lines of the coronal holes and the closed field line region of the heliospheric current sheet. Such a scenario would be consistent with previous X ray measurements which suggect that reconnection is occurring in this region.

  5. Measurement of accelerated electron beam current at the Erevan synchrotron

    International Nuclear Information System (INIS)

    A system which ensures high accuracy of accelerated electro n beam current measurement at the synchrotron is described. The expected limits for the frequency characteristic of the measured magnitude, i.e. current of accelerated electron beam, are analyzed. A structure of measurement devices ensuring a necessary frecuency range for measured signals is chosen. A magnetoinduction feedback converter operating in aperiodic mode is taken as a primary beam current monitor. The parameters of the converter with a coincidence amplifier were calculated with a computer. Oscillograms of accelerated electron beam current corresponding to different operational modes of the synchrotron are presented

  6. Current neutralization in ballistic transport of light ion beams

    International Nuclear Information System (INIS)

    Intense light ion beams are being considered as drivers to ignite fusion targets in the Laboratory Microfusion Facility (LMF). Ballistic transport of these beams from the diode to the target is possible only if the beam current is almost completely neutralized by plasma currents. This paper summarizes related work on relativistic electron beam and heavy ion beam propagation and describes a simple simulation model (DYNAPROP) which has been modified to treat light ion beam propagation. DYNAPROP uses an envelope equation to treat beam dynamics and uses rate equations to describe plasma and conductivity generation. The model has been applied both to the high current, 30 MeV Li+3 beams for LMF as well as low current, 1.2 MeV proton beams which are currently being studied on GAMBLE B at the Naval Research Laboratory. The predicted ratio of net currents to beam current is ∼0.1--0.2 for the GAMBLE experiment and ∼0.01 for LMF. The implications of these results for LMF and the GAMBLE experiments art discussed in some detail. The simple resistive model in DYNAPROP has well-known limitations in the 1 torr regime which arise primarily from the neglect of plasma electron transport. Alternative methods for treating the plasma response are discussed

  7. Bootstrap current of fast ions in neutral beam injection heating

    International Nuclear Information System (INIS)

    The bootstrap current of fast ions produced by neutral beam injection (NBI) is investigated in a large-aspect-ratio tokamak with circular cross-section under specific parameters. The bootstrap current density distribution and the total bootstrap current are reported. In addition, the beam bootstrap current always accompanies the electron return current due to the parallel momentum transfer from fast ions. With the electron return current taken into consideration, the net current density obviously decreases; at the same time, the peak of the current moves towards the central plasma. Numerical results show that the value of the net current depends sensitively not only on the angle of the NBI but also on the ratio of the velocity of fast ions to the critical velocity: the value of the net current is small for neutral beam parallel injection, but increases severalfold for perpendicular injection, and increases with increasing beam energy. (paper)

  8. Improved beam current densities at high voltages

    International Nuclear Information System (INIS)

    The performance of ion extractors is analyzed with crude approximations that show improved performance to be possible with the certain modifications. However, additional studies are required to evaluate the beam optics in the presence of the deformed grids

  9. High current precision long pulse electron beam position monitor

    CERN Document Server

    Nelson, S D; Fessenden, T J; Holmes, C

    2000-01-01

    Precision high current long pulse electron beam position monitoring has typically experienced problems with high Q sensors, sensors damped to the point of lack of precision, or sensors that interact substantially with any beam halo thus obscuring the desired signal. As part of the effort to develop a multi-axis electron beam transport system using transverse electromagnetic stripline kicker technology, it is necessary to precisely determine the position and extent of long high energy beams for accurate beam position control (6 - 40 MeV, 1 - 4 kA, 2 μs beam pulse, sub millimeter beam position accuracy.) The kicker positioning system utilizes shot-to-shot adjustments for reduction of relatively slow (< 20 MHz) motion of the beam centroid. The electron beams passing through the diagnostic systems have the potential for large halo effects that tend to corrupt position measurements.

  10. Application of data mining in beam current forecast

    International Nuclear Information System (INIS)

    Data mining technique is briefly introduced in the paper. The comparability of history beam current curves was analyzed first, then a method to forecast the beam current was put forward based on time sequence comparability study, and used in Hefei light source operational data analysis. The result indicates it's useful. (authors)

  11. Fast Beam Current Change Monitor for the LHC

    CERN Document Server

    Kral, Jan

    Stringent demands on the LHC safety and protection systems require improved methods of detecting fast beam losses. The Fast Beam Current Transformer (FBCT) is a measurement instrument, providing information about bunch-to-bunch intensity of the accelerated beam. This thesis describes the development of a new protection system based on the FBCT signal measurements. This system, the Fast Beam Current Change Monitor (FBCCM), measures the FBCT signal in a narrow frequency band and computes time derivation of the beam signal magnitude. This derivation is proportional to the beam losses. When the losses exceed a certain level, the FBCCM requests a beam dump in order to protect the LHC. The LHC protection will be ensured by four FBCCMs which will be installed into the LHC in July 2014. Six FBCCMs have been already constructed and their characteristics were measured with satisfactory results. The FBCCMs were tested by a laboratory simulation of the real LHC environment.

  12. Low Current, Long Beam Pulse with SLED

    International Nuclear Information System (INIS)

    The 3 km long linac at the Stanford Linear Accelerator Center (SLAC) is used for fixed target experiments such as E-155, with energies up to 50 GeV. The SLAC Energy Development (SLED) system increase the maximum no-load energy by a factor of 1.6, but it also causes a varying beam energy curve. To provide a long pulse or bunch train for the experiment the energy profile has to be flat. Besides more sophisticated methods such as varying the phase of two klystrons feeding one structure section as proposed in the NLC design, we describe the method used for E-155 in spring of 1997. The desired low charged beam didn't have any significant beam loading, but by inserting a 1800 phase notch during the SLED pulse, a beam pulse of up to 500 ns was achieved. The energy range without compensation would have been 15%, while with compensation the energy spread was reduced to about 0.15%. The phase notch was achieved by triggering a pair of two additional 180d0 phase switches about half a structure fill-time after the SLED pulse was triggered. Simulations are compared with the experimental result

  13. LogAmp electronics and Optical Transmission for the new SPS Beam Position Measurement System

    CERN Document Server

    Deplano, C; Gonzalez, J L; Savioz, J J

    2013-01-01

    A new front-end board is under development for the CERN SPS Multi ORbit Position System (MOPOS). Based on logarithmic amplifiers, it measures the beam position over a large dynamic range of beam intensities and resolves the multi-batch structure of the SPS beams. Analogue data are digitized at 10 MS/s, packed in frames by an FPGA and on every turn sent to the readout board, via a 2.4 Gb/s optical transmission link. A first prototype has been successfully tested with several SPS beams. This paper presents an overall description of the system and its capabilities highlighted by the first beam measurements.

  14. High-current runaway electron beam in a tokamak plasma

    International Nuclear Information System (INIS)

    An equilibrium of toroidal plasma with a large electron-beam current has been realized using the runaway effect in a tokamak. Reproducible runaway-mode discharges are obtained with pure hydrogen gas by the help of intense titanium flashing which results in a low electron density. The beam current is estimated to be more than a half of the total toroidal current. The equilibrium of this discharge is maintained by a strong vertical field because the beam pressure gives rise to an additional increase in Shafranov Λ. The beam pressure is estimated to be more than 80% of the total pressure. The kinetic energy and the spatial distributions of beam electrons are studied by seeing X-ray emission from a tungsten wire inserted into the plasma. The increase of Shafranov Λ due to beam pressure is enhanced by puffing gas into the discharge. (author)

  15. High-current negative-ion beam transport

    International Nuclear Information System (INIS)

    The requirements for transporting high-current, negative-ion beams are presented with particular emphasis on applications involving negative-hydrogen-ion beams. In addition to the usual matching and steering problems, particular attention must be paid to beam emittance growth in the transport system. Depending on the application, a number of approaches have been developed using both magnetic and electric lenses. I discuss the design considerations for transporting and matching these beams to radiofrequency quadrupole accelerators, and present a survey of the various types of beamlines now used for negative-ion beams

  16. Design and development of DCCT for measurement of beam current

    International Nuclear Information System (INIS)

    Charged Particle beams in accelerators need measurement of beam current during operations and diagnostics. The beam passes through a resonant cavity that is excited at a fixed resonant frequency and is maintained at a vacuum level as high as 10E-8 Ton. Non-intrusive method is needed for beam current measurement. DCCT is a non-intrusive, accurate and stable device that is widely used for measurement of the beam intensity in particle accelerators. DCCT is based on principle of flux gate magnetometers. It consists of magnetic modulator, magnetizing coils, sense coils, back end and front end electronics. A prototype DCCT for vacuum chamber of 24 mm nominal inner diameter is designed and developed at CnID. During laboratory experiments beam current is simulated by passing DC current generated by stable current source along the axis of the DCCT. In absence of beam current sense coils senses zero voltage. Even harmonics are generated at the output winding when DC current is passed and the magnitude of the 2nd harmonic gives the corresponding value of the beam current. The prototype DCCT is designed for 0.5 mA to 10 mA range with resolution better than 0.1 mA. This paper describes the magnetic, electronics and mechanical design of the prototype DCCT which is optimized for amplitude and frequency of magnetizing current. The dependence of the amplitude and frequency of the magnetizing current on the second harmonic is discussed in detail. Shielding to external noise is provided with help of high permeability soft magnetic material. A compensation core with coil is used to determine the direction/charge of the beam. The current in this coil is tuned to reduce the 2nd harmonics generated due to beam current, back to zero. The value of this current gives magnitude of the beam current and its polarity gives information on direction/charge of the beam. Front and back end electronics designed for prototype DCCT is also discussed. It is planned to deploy the developed DCCT in Linac

  17. Computer simulation of high current uranium beams for the injection beam line of the UNILAC

    International Nuclear Information System (INIS)

    In an attempt to generate an ion beam with high current and high brightness for the design ion, the computer code KOBRA3-INP has been used to evaluate the extraction system, the DC post-acceleration system as well as the quadrupole transport beam line, and to study the behavior of the ion beam in the combined system. (orig.)

  18. The development of beam current monitors in the APS

    International Nuclear Information System (INIS)

    The Advanced Photon Source (APS) is a third-generation 7-GeV synchrotron radiation source. The precision measurement of beam current is a challenging task in high energy accelerators, such as the APS, with a wide range of beam parameters and complicated noise, radiation, and thermal environments. The beam pulses in the APS injector and storage ring have charge ranging from 50pC to 25nC with pulse durations varying from 30ps to 30ns. A total of nine non- intercepting beam current monitors have been installed in the APS facility (excluding those in the linac) for general current measurement. In addition, several independent current monitors with specially designed redundant interlock electronics are installed for personnel safety and machine protection. This paper documents the design and development of current monitors in the APS,. discusses the commissioning experience in the past year, and presents the results of recent operations

  19. Electrical measurement techniques for pulsed high current electron beams

    International Nuclear Information System (INIS)

    The advent of high current (1 to 100 kA), moderate energy (>10 MeV), short pulse (1 to 100 ns) electron accelerators used for charged particle beam research has motivated a need to complement standard diagnostics with development of new diagnostic techniques to measure electron beam parameters. A brief survey is given of the diagnostics for measuring beam current, position, size, energy, and emittance. While a broad scope of diagnostics will be discussed, this survey will emphasize diagnostics used on the Experimental Test Accelerator (ETA) and Advanced Test Accelerator (ATA). Focus is placed on diagnostics measuring beam current, position and size. Among the diagnostics discussed are resistive wall current monitors, B/sub theta/ loops, Rogowski coils, Faraday cups, and x-ray wire diagnostics. Operation at higher current levels also increases radiation and electromagnetic pulse interference. These difficulties and methods for circumventing them are also discussed

  20. Enhancing the accelerated beam current in the booster synchrotron by optimizing the transport line beam propagation

    Indian Academy of Sciences (India)

    Saini R S; Tyagi Y; Ghodke A D; Puntambekar T A

    2016-04-01

    In this paper, we present the results of transverse beam emittance and twiss parameter measurement of an electron beam, delivered by a 20 MeV microtron which is used as a pre-injector system for a booster synchrotron in the Indus Accelerator Facility at RRCAT Indore. Based on these measured beam parameters, beam optics of a transport line was optimized and its results are alsodiscussed in this paper. This beam transport line is used to transport the electron beam from the 20MeV microtron to the booster synchrotron. The booster synchrotron works as a main injector for Indus-1 and Indus-2 synchrotron radiation facilities. To optimize the beam optics of a transport linefor proper beam transmission through the line as well as to match the beam twiss parameters at the beam injection point of another accelerator, it is necessary to know the transverse beam emittance and twiss parameters of the beam coming from the first one. A MATLAB-based GUI program has been developed to calculate the beam emittance and twiss parameters, using quadrupole scanmethod. The measured parameters have been used for beam transport line optimization and twiss parameters matching at booster injection point. After this optimization, an enhancement of ∼50% beam current has been observed in the booster synchrotron.

  1. Low Starting Electron Beam Current in Degenerate Band Edge Oscillators

    CERN Document Server

    Othman, Mohamed A K; Figotin, Alexander; Capolino, Filippo

    2016-01-01

    We propose a new principle of operation in vacuum electron-beam-based oscillators that leads to a low beam current for starting oscillations. The principle is based on super synchronous operation of an electron beam interacting with four degenerate electromagnetic modes in a slow-wave structure (SWS). The four mode super synchronous regime is associated with a very special degeneracy condition in the dispersion diagram of a cold periodic SWS called degenerate band edge (DBE). This regime features a giant group delay in the finitelength SWS and low starting-oscillation beam current. The starting beam current is at least an order of magnitude smaller compared to a conventional backward wave oscillator (BWO) of the same length. As a representative example we consider a SWS conceived by a periodically-loaded metallic waveguide supporting a DBE, and investigate starting-oscillation conditions using Pierce theory generalized to coupled transmission lines (CTL). The proposed super synchronism regime can be straightf...

  2. Limiting current of intense electron beams in a decelerating gap

    Science.gov (United States)

    Nusinovich, G. S.; Beaudoin, B. L.; Thompson, C.; Karakkad, J. A.; Antonsen, T. M.

    2016-02-01

    For numerous applications, it is desirable to develop electron beam driven efficient sources of electromagnetic radiation that are capable of producing the required power at beam voltages as low as possible. This trend is limited by space charge effects that cause the reduction of electron kinetic energy and can lead to electron reflection. So far, this effect was analyzed for intense beams propagating in uniform metallic pipes. In the present study, the limiting currents of intense electron beams are analyzed for the case of beam propagation in the tubes with gaps. A general treatment is illustrated by an example evaluating the limiting current in a high-power, tunable 1-10 MHz inductive output tube (IOT), which is currently under development for ionospheric modification. Results of the analytical theory are compared to results of numerical simulations. The results obtained allow one to estimate the interaction efficiency of IOTs.

  3. RADLAC II high current electron beam propagation experiment

    International Nuclear Information System (INIS)

    The resistive hose instability of an electron beam was observed to be convective in recent RADLAC II experiments for higher current shots. The effects of air scattering for these shots were minimal. These experiments and theory suggest low-frequency hose motion which does not appear convective may be due to rapid expansion and subsequent drifting of the beam nose

  4. Development of an external Faraday cup for beam current measurements

    International Nuclear Information System (INIS)

    In general, beam current measurements are very important for many kinds of experiments using highly energetic particle beams at accelerators, such as cyclotrons, linacs, etc. The Faraday cup is known to be one of the most popular beam current measurement tools. We developed an external Faraday cup to measure the beam current at a dedicated beam line for low-flux experiments installed at the MC-50 cyclotron of Korea Institute of Radiological and Medical Sciences (KIRAMS). It was designed for external beam current measurements and is composed of a vacuum chamber, an entrance window, a collimator, a electrostatic suppressor ring, and a cup. The window is made of 75-um-thick Kapton film, and the diameter of the collimator is 10 mm or 20 mm. The ring and the cup has 5-cm inner diameters, and the thickness of the bottom of the cup is 2 cm, which is enough to absorb the total proton energy up to 45 MeV. Using this external Faraday cup, we measured the beam current from the cyclotron, and we compared measured flux to the results from film dosimetry using GAF films.

  5. Dynamics of a high-current relativistic electron beam

    International Nuclear Information System (INIS)

    The dynamics of a high-current relativistic electron beam is studied experimentally and by numerical simulation. The beam is formed in a magnetically insulated diode with a transverse-blade explosive-emission cathode. It is found experimentally that the radius of a 500-keV beam with a current of 2 kA and duration of 500 ns decreases with time during the beam current pulse. The same effect was observed in numerical simulations. This effect is explained by a change in the shape of the cathode plasma during the current pulse, which, according to calculations, leads to a change in the beam parameters, such as the electron pitch angle and the spread over the longitudinal electron momentum. These parameters are hard to measure experimentally; however, the time evolution of the radial profile of the beam current density, which can be measured reliably, coincides with the simulation results. This allows one to expect that the behavior of the other beam parameters also agrees with numerical simulations

  6. Production of high-efficiency microsecond heavy-current beams

    International Nuclear Information System (INIS)

    The comparative analysis of various constructions of diodes with magnetic insulation is reported. It is shown that the diode current leakage decrease results in increase of pulse duration of relativistic electron beam and diode efficiency. A ring high quality electron beam of 0.6 MeV energy, current - 3-4 kA, duration - 2.5 μs and ring width 0.8 - 1 mm is obtained

  7. Neutral beam current drive scaling in DIII-D

    International Nuclear Information System (INIS)

    Neutral beam current drive scaling experiments have been carried out on the DIII-D tokamak at General Atomics. These experiments were performed using up to 10 MW of 80 keV hydrogen beams. Previous current drive experiments on DIII-D have demonstrated beam driven currents up to 340 kA. In the experiments reported here we achieved beam driven currents of at least 500 kA, and have obtained operation with record values of poloidal beta (εβ/sub p/ = 1.4). The beam driven current reported here is obtained from the total plasma current by subtracting an estimate of the residual Ohmic current determined from the measured loop voltage. In this report we discuss the scaling of the current drive efficiency with plasma conditions. Using hydrogen neutral beams, we find the current drive efficiency is similar in Deuterium and Helium target plasmas. Experiments have been performed with plasma electron temperatures up to T/sub e/ = 3 keV, and densities in the range 2 /times/ 1019m/sup /minus/3/ 19m/sup /minus/3/. The current drive efficiency (nIR/P) is observed to scale linearly with the energy confinement time on DIII-D to a maximum of 0.05 /times/ 1020m/sup /minus/2/ A/W. The measured efficiency is consistent with a 0-D theoretical model. In addition to comparison with this simple model, detailed analysis of several shots using the time dependent transport code ONETWO is discussed. This analysis indicates that bootstrap current contributes approximately 10--20% of the the total current. Our estimates of this effect are somewhat uncertain due to limited measurements of the radial profile of the density and temperatures. 4 refs., 1 fig., 1 tab

  8. Large Dynamic Range Beam Profile Measurements with Low Current Electron Beams

    International Nuclear Information System (INIS)

    Large dynamic range [Peak/Noise > 105] beam profile measurements are routinely performed in the Hall-B beamline at Jefferson Lab. These measurements are made with a 1 to 10nA electron beam current with energies between 1 to 6 GeV. The electron beam scatters off of a thin [25 mu-m] W or Fe wire and the scattered particle/shower is detected via scintillation or Cerenkov light several meters downstream of the wire. This light is converted to an electrical pulse via photomultiplier tubes [PMT]. The PMT readout and wire motion are controlled and synchronized by VME electronics. This report describes results on increasing the dynamic range by using multiple wires of varying diameters. Profile measurements with this large dynamic range can be of use for machines with very large beam currents (ERL) where any FR-actional beam loss represents a significant amount of beam power [1,2

  9. Measurement and physical interpretation of the mean motion of turbulent density patterns detected by the beam emission spectroscopy system on the mega amp spherical tokamak

    International Nuclear Information System (INIS)

    The mean motion of turbulent patterns detected by a two-dimensional beam emission spectroscopy (BES) diagnostic on the mega amp spherical tokamak (MAST) is determined using a cross-correlation time delay method. Statistical reliability of the method is studied by means of synthetic data analysis. The experimental measurements on MAST indicate that the apparent mean poloidal motion of the turbulent density patterns in the lab frame arises because the longest correlation direction of the patterns (parallel to the local background magnetic fields) is not parallel to the direction of the fastest mean plasma flows (usually toroidal when strong neutral-beam injection is present). This effect is particularly pronounced in a spherical tokamak because of the relatively large mean rotation and large magnetic pitch angle. The experimental measurements are consistent with the mean motion of plasma being toroidal. The sum of all other contributions (mean poloidal plasma flow, phase velocity of the density patterns in the plasma frame, non-linear effects, etc) to the apparent mean poloidal velocity of the density patterns is found to be negligible. These results hold in all investigated L-mode, H-mode and internal transport barrier discharges. The one exception is a high-poloidal-beta (the ratio of the plasma pressure to the poloidal magnetic field energy density) discharge, where a large magnetic island exists. In this case BES detects very little motion. This effect is currently theoretically unexplained. (paper)

  10. Beam centroid motion estimate for a high current LIA

    International Nuclear Information System (INIS)

    A high current linear induction accelerator now is being constructed in Institute of Fluid Physics. It consists of 18 blocks, totally 72 induction accelerating cells, and 18 connection cells with ports for beam diagnostic hardware and vacuum pump. The goal of the facility is to obtain high quality, high current pulse electron beams. In order to reduce corkscrew motion caused by energy spread and misalignment of a focusing system some measures to control the transverse motion of beam centroid must be taken. At first magnetic alignment is performed by using pulsed-wire technique very carefully, then the tilt errors is corrected by a pair of steering coils, which are located inside each cell, after that based on the alignment data a simple estimate of the beam centroid motion has been done by transfer matrix algorithm. In this paper, the calculated and analysis results are presented

  11. Magnetoinduction sensor of beam current with magnetic noise screening

    International Nuclear Information System (INIS)

    A description is given of a magnetoinduction sensor of beam current in a synchrotron, the latter being a booster of the VEhPP-4 electron-positron complex. The sensor operates under conditions of heavy background noise induced by the synchrotron pulsed magnetic fields. The means reducing the noise level in the sensor are considered. The most efficient screen protecting against pulsed fields is one made of conducting materials where the field is reduced at the expense of induced currents passing in a skin-layer. The screen has an azimuthal slit, which results in the beam vortex field penetration to the sensor without reduction. The noise field is reduced due to the conducting walls and deep slit. Application of the means deseribed allowed to measure low (of the order of 100 mcA) synchrotron beam currents

  12. Plasma Charge Current for Controlling and Monitoring Electron Beam Welding with Beam Oscillation

    Science.gov (United States)

    Trushnikov, Dmitriy; Belenkiy, Vladimir; Shchavlev, Valeriy; Piskunov, Anatoliy; Abdullin, Aleksandr; Mladenov, Georgy

    2012-01-01

    Electron beam welding (EBW) shows certain problems with the control of focus regime. The electron beam focus can be controlled in electron-beam welding based on the parameters of a secondary signal. In this case, the parameters like secondary emissions and focus coil current have extreme relationships. There are two values of focus coil current which provide equal value signal parameters. Therefore, adaptive systems of electron beam focus control use low-frequency scanning of focus, which substantially limits the operation speed of these systems and has a negative effect on weld joint quality. The purpose of this study is to develop a method for operational control of the electron beam focus during welding in the deep penetration mode. The method uses the plasma charge current signal as an additional informational parameter. This parameter allows identification of the electron beam focus regime in electron-beam welding without application of additional low-frequency scanning of focus. It can be used for working out operational electron beam control methods focusing exactly on the welding. In addition, use of this parameter allows one to observe the shape of the keyhole during the welding process. PMID:23242276

  13. Quadrupole betatron accelerator for high current ion beams

    International Nuclear Information System (INIS)

    Properties of a strong non-neutral ion ring in a quadrupole betatron field are investigated. Superimposed on the axial betatron field, it is shown that the quadrupole field is necessary for the stability of the orbits where the self-fields of the ion ring are not negligible. A closed algebraic expression for the ion limiting current is obtained in terms of the quadarupole field intensity, the channel radius, the transverse temperature of ion beam, and the strength of betatron field. According to the theoretical calculation, high energy ion beam with its current order of one kiloampere can easily be attainable

  14. DPSS Laser Beam Quality Optimization Through Pump Current Tuning

    Energy Technology Data Exchange (ETDEWEB)

    Omohundro, Rob; /Newport Spectra-Physics, Santa Clara; Callen, Alice; /SLAC; Sukuta, Sydney; /San Jose City Coll.

    2012-03-30

    The goal of this study is to demonstrate how a DPSS laser beam's quality parameters can be simultaneously optimized through pump current tuning. Two DPSS lasers of the same make and model were used where the laser diode pump current was first varied to ascertain the lowest RMS noise region. The lowest noise was found to be 0.13% in this region and the best M{sup 2} value of 1.0 and highest laser output power were simultaneously attained at the same current point. The laser manufacturer reported a M{sup 2} value of 1.3 and RMS noise value of .14% for these lasers. This study therefore demonstrates that pump current tuning a DPSS laser can simultaneously optimize RMS Noise, Power and M{sup 2} values. Future studies will strive to broaden the scope of the beam quality parameters impacted by current tuning.

  15. Ion collective acceleration and high current beam transport

    International Nuclear Information System (INIS)

    Results of investigation of high-current beam (HCB) transport in vacuum channels with dielectric walls (VCDW) are presented. It is shown, that HCB transport can be realized not only in rectilinear dielectric channels, but also in curvili also in curvilitear oges. In particular, it proved to be possible to bend the beam with parameters 50 kA, 400 keV by 90 deg. A problem of negative ion intense beam production is considered. It is shown, that in magnetic insulation diodes hydrogen ion currents of about several kA are obtained at current densities 10 A/cm2. Results of collective ion acceleration in VCDW are given. Two regions with different physical mechanisms of ion acceleration should be distinguished. In the first region (''plasma''), corresponding to HCB motion in VCDW ion generation and their acceleration in quasipotential field of HCB up to the energy of the order of electrons or less takes place. In the second region (''beam''), corresponding to joint motion of ''extracted'' ions and HCB electrons, ion acceleration takes place in the fields of waves, which can be excited due to the mechanism of two-beam instability type. Considerable contribution can also be made by stochastic mechanism of ion acceleration

  16. Analysis of electron current instability in E-beam writer

    Czech Academy of Sciences Publication Activity Database

    Bok, Jan; Horáček, Miroslav; Král, Stanislav; Kolařík, Vladimír; Matějka, František

    Ostrava : TANGER Ltd, 2012, s. 295-299. ISBN 978-80-87294-32-1. [NANOCON 2012. International Conference /4./. Brno (CZ), 23.10.2012-25.10.2012] R&D Projects: GA MŠk ED0017/01/01; GA TA ČR TE01020118; GA MPO FR-TI1/576 Institutional support: RVO:68081731 Keywords : electron beam * current measurement * current drift and noise * fourier analysis Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  17. On neutral-beam injection counter to the plasma current

    Science.gov (United States)

    Helander, P.; Akers, R. J.; Eriksson, L.-G.

    2005-11-01

    It is well known that when neutral beams inject ions into trapped orbits in a tokamak, the transfer of momentum between the beam and the plasma occurs through the torque exerted by a radial return current. It is shown that this implies that the angular momentum transferred to the plasma can be larger than the angular momentum of the beam, if the injection is in the opposite direction to the plasma current and the beam ions suffer orbit losses. On the Mega-Ampere Spherical Tokamak (MAST) [R. J. Akers, J. W. Ahn, G. Y. Antar, L. C. Appel, D. Applegate, C. Brickley et al., Plasma Phys. Controlled Fusion 45, A175 (2003)], this results in up to 30% larger momentum deposition with counterinjection than with co-injection, with substantially increased plasma rotation as a result. It is also shown that heating of the plasma (most probably of the ions) can occur even when the beam ions are lost before they have had time to slow down in the plasma. This is the dominant heating mechanism in the outer 40% of the MAST plasma during counterinjection.

  18. Practical application High-Tc SQUID beam current monitor

    International Nuclear Information System (INIS)

    To measure the DC current of heavy-ion beams non-destructively at high resolution, we have developed a high critical temperature (HTc) superconducting quantum interference device (SQUID) beam current monitor for use in the radioactive isotope beam factory (RIBF) at RIKEN. Unlike at other existing facilities, a low vibration, pulse-tube refrigerator cools the HTc fabrications including the SQUID in such a way that the size of the system is reduced and the running costs are lowered. Last year, the magnetic shielding system has been greatly reinforced. The new strong magnetic shielding system can attenuate the external magnetic noise to 10-10. Aiming at its practical use for acceleration operation, the prototype HTc SQUID monitor was disassembled, exchange the improved parts and re-assembled. Beginning this year, we have installed the HTc SQUID monitor in the beam transport line in the RIBF. Here we report the present details of the developed HTc SQUID monitor system and the results of the beam measurement. (author)

  19. First test of BNL electron beam ion source with high current density electron beam

    Science.gov (United States)

    Pikin, Alexander; Alessi, James G.; Beebe, Edward N.; Shornikov, Andrey; Mertzig, Robert; Wenander, Fredrik; Scrivens, Richard

    2015-01-01

    A new electron gun with electrostatic compression has been installed at the Electron Beam Ion Source (EBIS) Test Stand at BNL. This is a collaborative effort by BNL and CERN teams with a common goal to study an EBIS with electron beam current up to 10 A, current density up to 10,000 A/cm2 and energy more than 50 keV. Intensive and pure beams of heavy highly charged ions with mass-to-charge ratio heavy ion research facilities including NASA Space Radiation Laboratory (NSRL) at BNL and HIE-ISOLDE at CERN. With a multiampere electron gun, the EBIS should be capable of delivering highly charged ions for both RHIC facility applications at BNL and for ISOLDE experiments at CERN. Details of the electron gun simulations and design, and the Test EBIS electrostatic and magnetostatic structures with the new electron gun are presented. The experimental results of the electron beam transmission are given.

  20. Return Current Electron Beams and Their Generation of "Raman" Scattering

    Science.gov (United States)

    Simon, A.

    1998-11-01

    For some years, we(A. Simon and R. W. Short, Phys. Rev. Lett. 53), 1912 (1984). have proposed that the only reasonable explanation for many of the observations of "Raman" scattering is the presence of an electron beam in the plasma. (The beam creates a bump-on-tail instability.) Two major objections to this picture have been observation of Raman when no n_c/4 surface was present, with no likely source for the electron beam, and the necessity for the initially outward directed beam to bounce once to create the proper waves. Now new observations on LLE's OMEGA(R. Petrasso et al), this conference. and at LULI(C. Labaune et al)., Phys. Plasma 5, 234 (1998). have suggested a new origin for the electron beam. This new scenario answers the previous objections, maintains electron beams as the explanation of the older experiments, and may clear up puzzling observations that have remained unexplained. The new scenario is based on two assumptions: (1) High positive potentials develop in target plasmas during their creation. (2) A high-intensity laser beam initiates spark discharges from nearby surfaces to the target plasma. The resulting return current of electrons should be much more delta-like, is initially inwardly directed, and no longer requires the continued presence of a n_c/4 surface. Scattering of the interaction beam from the BOT waves yields the observed Raman signal. Experimental observations that support this picture will be cited. ``Pulsation'' of the scattering and broadband ``flashes'' are a natural part of this scenario. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460.

  1. Beam position dependence of a wall-current monitor

    International Nuclear Information System (INIS)

    It was pointed out recently that there exists an appreciable beam position dependence in the wall-current monitor widely used in electron accelerators. Detailed study of this dependence is performed on a test bench varying the pulse width and the frequency of the input signal simulating the beam. The results of experiments show that when the pulse width becomes shorter more appreciable becomes the dependence, and it approaches to that of calculated from the method of images. A unified analysis is under way. (author)

  2. Squeezed state of high-current electron beam

    International Nuclear Information System (INIS)

    The results of the computer simulation of an electron beam propagating serially through two coaxial tubes with different radii are presented. It is shown that the virtual cathode in this system may be located in one of two positions depending on the injection current, variation of which yields fast movements of the potential barrier. Under certain conditions, a part of the beam may be in its squeezed state, forming, therefore, a cloud of a dense warm plasma. The qualitative analytical theory based on the consideration of the energy and momentum balance is also discussed

  3. Beam dynamics studies of high current RF and DTL tanks

    International Nuclear Information System (INIS)

    An accelerator for spallation breeding of fissile fuel must have low beam loss and high acceleration efficiency. An extensive investigation using the PARMTEQ and PARMILA computer beam dynamics codes has been undertaken to obtain a reference design for a 100% duty cycle 300 mA 10 MeV proton linac called ZEBRA (Zero Energy BReeder Accelerator) that could serve as the first stage of an accelerator-breeder. This paper discusses results of this investigation, showing how current carrying capacity and accelerating efficiency in both RFQ's and DTL's is affected by accelerator and injector parameters

  4. Collective monitors for high-current pulse electron beam diagnostics

    International Nuclear Information System (INIS)

    A collector monitor for high-current pulsed electron beams at average power of 100 W and pulse current of 100 A has been developed. The monitor comprises a Faraday cup, profile monitor, sector diaphragm, energy detector. The collector was fixed on a brass radiator transformed into a rod. The rod ensures reliable and electric contact of the collector with the ''earth'' and small RC of this line. Such design permits to stabilize the heat mode of the collector without utilization of external cooling. The monitors have been tested in electron beams at head load up to 100 W during 40 hours. Wear at the expense of evaporation, microexplosions were not observed. Accuracy of current measuring made up 5-10% for absolute and 1-2% for relative measurements

  5. Neoclassical current effects in neutral beam-heated tokamaks

    International Nuclear Information System (INIS)

    There is a long-standing prediction from neoclassical theory that strong contributions to the toroidal current should be driven by friction between trapped and passing particles when β/sub pol/ exceeds √R/a in a tokamak. A number of neutral beam heating experiments can now produce such parameters, and it is of interest to calculate the behavior which should occur in this regime to determine the feasibility of using such a bootstrap current as a steady-state tokamak current source. Since gross manifestations are absent in a wide range of experiments on the Impurity Study Experiment (ISX-B), as reported earlier, the conclusion is that the neoclassical current, if present, can have a value no larger than 25% of its theoretically calculated value. Since the neoclassical particle (Ware) pinch is strongly related to the neoclassical current in the theory (Onsager reciprocity), the existence of the particle pinch is thus called into question

  6. Electron beam induced current in photovoltaics with high recombination

    OpenAIRE

    Haney, Paul M.; Yoon, Heayoung P.; Koirala, Prakash; Collins, Robert W.; Zhitenev, Nikolai B.

    2014-01-01

    Electron beam induced current (EBIC) is a powerful characterization technique which offers the high spatial resolution needed to study polycrystalline solar cells. Ideally, an EBIC measurement reflects the spatially resolved quantum efficiency of the device. In this work, a model for EBIC measurements is presented which applies when recombination within the depletion region is substantial. This model is motivated by cross-sectional EBIC experiments on CdS-CdTe photovoltaic cells which show th...

  7. A review of high beam current RFQ accelerators and funnels

    International Nuclear Information System (INIS)

    The authors review the design features of several high-current (> 20-mA) and high-power (> 1-mA average) proton or H- injectors, RFQs, and funnels. They include a summary of observed performance and will mention a sampling of new designs, including the proposed incorporation of beam choppers. Different programs and organizations have chosen to build the RFQ in diverse configurations. Although the majority of RFQs are either low-current or very low duty-factor, several versions have included high-current and/or high-power designs for either protons or H- ions. The challenges of cooling, handling high space-charge forces, and coupling with injectors and subsequent accelerators are significant. In all instances, beam tests were a valuable learning experience, because not always did these as-built structures perform exactly as predicted by the earlier design codes. They summarize the key operational parameters, indicate what was achieved, and highlight what was learned in these tests. Based on this generally good performance and high promise, even more challenging designs are being considered for new applications that include even higher powers, beam funnels and choppers

  8. Neutral Beam Current Drive in Spheromak plasma and plasma stability

    Science.gov (United States)

    Pearlstein, L. D.; Jayakumar, R. J.; Hudson, B.; Hill, D. N.; Lodestro, L. L.; McLean, H. S.; Fowler, T. K.; Casper, T. A.

    2007-11-01

    A key question for the Sustained Spheromak Physics Experiment (SSPX) is understanding how spheromaks can be sustained by other current drive tools such as neutral beam current drive. Another question is whether the present relationship between current and maximum spheromak magnetic field (plasma beta) is related to Alcator-like ohmic confinement limit or is a stability limit. Using the code CORSICA, the fraction of neutral beam current drive that can be achieved has been calculated for different injection angles with a fixed equilibrium. It is seen that relaxing the equilibrium with this drive simply drives the core safety factor to low values. Other equilibria where the NBI may give aligned current drive are being explored. Free-boundary equilibria calculations are underway to see what hyper-resistivity model gives the observed sustained SSPX performance and include that in the NBI calculations. Work performed under the auspices of the US DOE by University of California Lawrence Livermore National Laboratory under contract W-7405-ENG-48.

  9. Shaping of electron beam picosecond current pulses in waveguide accelerators

    International Nuclear Information System (INIS)

    Results are given of experiments on extracting a single bunch in an experimental SHF wavegujde accelerator operating in the stoped energy mode. The accelerator has the following parameters: 8 MeV energy, 1818 MHz frequency of the accelerating field, 10 ns pulse duration of current; 20 A pulsed current, operation in the mode of single massages. An electron beam in the shape of a 10 ns pulse has been injected into the waveguide at the end of a SHF-pulse. The shape of detected picosecond pulses of accelerated electron current is close to triangular one, pulse duration at half-height with correction for rise time of the measuring system is equal to 50 ps, pulse current is about 100 A, electron energy equals 8 MeV

  10. Sensitivity improvement of beam current monitor with a high-Tc current sensor and SQUID

    International Nuclear Information System (INIS)

    It is widely recognized that non-destructive measurement at high resolution of the DC current of high-energy heavy-ion beams is important. Therefore, a high critical temperature (HTc) superconducting quantum interference device (SQUID) beam current monitor has been developed for use in the radioactive isotope beam factory (RIBF) at RIKEN in Japan. Unlike at other existing facilities, a low-vibration, pulse-tube refrigerator cools the HTc fabrications including the SQUID in such a way that the size of the system is reduced and the running costs are lowered. As a result, using a prototype of the HTc SQUID monitor, the intensity of a 4 μA Xe beam (10.8 MeV/u) was successfully measured with 100 nA resolution. Furthermore, since higher resolution is necessary, development of an improved HTc current sensor with two coils has begun. A spaying machine was developed to fabricate the new HTc current sensor by dip-coating a thin layer of Bi2-Sr2-Ca2-Cu3-Ox (Bi-2223) onto a 99.7% MgO ceramic substrate. Results from a new HTc current sensor produced using this machine are reported here. (author)

  11. Hybrid monitor for both beam position and tilt of pulsed high-current beams

    International Nuclear Information System (INIS)

    A Hybrid beam monitor, integrated with both azimuthal and axial B-dot probes, was designed for simultaneous measurement of both beam position and beam angle for pulsed high-current beams at the same location in beam pipe. The output signals of axial B-dot probes were found to be mixed with signals caused by transverse position deviation. In order to eliminate the unwanted signals, an elimination method was developed and its feasibility tested on a 50-Ω coaxial line test stand. By this method, a waveform, shape-like to that of input current and proportional to the tilt angle, was simulated and processed by following integration step to achieve the tilt angle. The tests showed that the measurement error of displacement and tilt angle less than 0.3 mm and 1.5 mrad, respectively. The latter error could be reduced with improved probes by reducing the inductance of the axial B-dot probe, but the improvement reached a limit due to some unknown systemic mechanism

  12. Current to frequency converter for digitization of millisecond beam signals

    International Nuclear Information System (INIS)

    Beam-intensity monitoring in the Fermilab Neutrino Area requires sensitive and fast processing for beam signals (with four or five decade amplitude variations for a typical detector) which are digitized with a current-to-frequency converter (IFC). The converter digitizes the input charge at a 1 pC/Hz rate with a processing limit at 10 MHz for a 10 nC charge input or a 10 ;mu;A current input. For a 1 ms beam pulse, the IFC can generate a 1 to 10,000 count output. The digitizer is two to three decades more sensitive than the fastest commercial V to F converters and the upper frequency limit is two or three decades higher than the present laboratory built IFC's. The resolution over the 0 to 50 C temperature range and the linearity from 1 Hz to 1 MHz is held to ;plus or minus;1% with a linearity deviation of +5% at 10 MHz. 3 refs

  13. Beam current transformer (BCT) for experiment WA1/2

    CERN Multimedia

    1978-01-01

    In experiment WA1/2, a 400 GeV proton beam from the SPS was directed at a target, downstream of which a hadron line selected, in several narrow momentum bands, a beam of either pi+ and K+ or pi- and K-. These neutrino-parent particles, before entering a 292 m long decay tunnel, passed through a set of 2 BCTs of a design seen here. They measured the hadron intensity (10^10 to 10^11 particles/pulse) with a precision of the order of 1%. There were 2 of them, for enhanced precision and confidence. After the discovery of neutral currents in the Gargamelle-experiment, WA1/2 was the first follow-up, high-precision experiment (Z.Phys.C35, 443-452, 1987 and Z.Phys.C45, 361-379, 1990). See also 7706516X.

  14. Collective ion acceleration in high current relativistic electron beams

    International Nuclear Information System (INIS)

    This report describes the progress made during the current contract period investigating the use of high power relativistic electron beams for electron and ion acceleration. Section 2 gives a summary of results from the relativistic klystron experiment and details our plans for a large diameter coaxial system. Section 3 summarizes our efforts to generate upper hybrid waves on relativistic electron beams. Simulation work of the upper hybrid excitation process is reported. Our experiment using high power microwaves for electron acceleration is discussed. This paper also reports progress on development of repetitive pulsed experimental and data acquisition systems. Our future research plans are outlined, followed by a list of publications and presentations from our present work. 10 figs

  15. Mapping ion beam induced current changes in a commercial MOSFET

    Energy Technology Data Exchange (ETDEWEB)

    Alves, A.D.C.; Thompson, S.; Yang, C. [School of Physics, University of Melbourne, Victoria 3010 (Australia); Jamieson, D.N., E-mail: d.jamieson@unimelb.edu.au [School of Physics, University of Melbourne, Victoria 3010 (Australia)

    2011-10-15

    We demonstrate a novel nuclear microprobe imaging and analysis modality for micrometre-scale field effect transistor devices probed with focused beams of MeV ions. By recording the drain current as a function of time during ion irradiation it is possible to identify current transients induced by the passage of single ions through the sensitive structures of the device. This modality takes advantage of the fact that the ionization produced by the passage of a single ion acts in an equivalent way to a transient change in the gate bias which therefore modulates the drain current as a function of time. This differs from the traditional ion beam induced charge technique where the ionization drifts in an internal electric field and induces a single charge pulse in an electrode applied to the device. Instead a richer variety of phenomena are observed, with different time constants which depend on the proximity of the ion strike to the channel of the device. The signals may be used to examine device function, radiation sensitivity or to count ion impacts within the channel.

  16. Neoclassical current effects in neutral-beam-heated tokamak discharges

    International Nuclear Information System (INIS)

    There is a long-standing prediction from neoclassical theory that strong contributions to the toroidal current should be driven by friction between trapped and passing particles when βsub(pol) exceeds root (R/a) in a tokamak. A number of neutral-beam heating experiments can now produce such parameters, and it is of interest to calculate the behaviour which should occur in this regime to determine the feasibility of using such a 'bootstrap' current as a steady-state tokamak current source. It is found that the neoclassical current should be large enough to reverse the external loop voltage for typical experimental parameters (ISX-B, in particular) in cases where the total current is fixed and to produce a detectable excess of total current above the pre-programmed (demand) value in cases where the loop voltage is regulated. Other manifestations of such a current should be either: a sharp rise in the central q-value (producing a cessation of internal m=1 and m=2 MHD activity), with an enhancement by two orders of magnitude of ion thermal conductivity (due to the formation of a hollow current density profile and a consequent drop in local values of the poloidal magnetic field in the central plasma region), or an enhanced tendency for disruption (arising from magnetic reconnection in hollow-profile equilibria). Since these gross manifestations are absent in a wide range of experiments on the Impurity Study Experiment (ISX-B), as reported earlier, the conclusion is that the neoclassical current, if present, can have a value no larger than 25% of its theoretically calculated value. Since the neoclassical particle (Ware) pinch is strongly related to the neoclassical current in the theory (Onsager reciprocity), the existence of the particle pinch is thus called into question. (author)

  17. Neutral Beam Heating and Current Drive in MAST

    Science.gov (United States)

    Akers, R.; Challis, C.; Appel, L.; Conway, N.; Cunningham, G.; Gryaznevich, M.; Lloyd, B.; Patel, A.; Tabasso, A.; Tournianski, M.

    2002-11-01

    Primary auxiliary heating on MAST (R 0.8m, a 0.6m) is provided by two ORNL neutral-beam injectors, oriented in the mid-plane, each with a tangency radius of 0.7m. Centrally peaked heating profiles at electron densities routinely exceeding the Greenwald limit are generated by injecting in the range 40 co-injection heated discharges and for low current (Ip 300kA), low-density (ne>0.5x1019m-3) co and counter injection heated plasmas where NBCD is being investigated.

  18. Development of beam current control system in RF-knockout slow extraction

    Energy Technology Data Exchange (ETDEWEB)

    Mizushima, K., E-mail: mizshima@nirs.go.jp [Department of Accelerator and Medical Physics, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Graduate School of Science and Technology, Chiba University, Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Sato, S.; Shirai, T.; Furukawa, T.; Katagiri, K.; Takeshita, E.; Iwata, Y.; Himukai, T.; Noda, K. [Department of Accelerator and Medical Physics, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan)

    2011-12-15

    A raster scanning method has been developed for cancer therapy at NIRS-HIMAC. This method requires a high-accuracy beam current control and fast beam-on/off switching. We have developed a feedback control system of the beam current with the RF-knockout slow extraction method. The system has allowed a stable response to beam-on/off switching using a feedback control delay function with a beam-current ripple of 7%.

  19. First test of BNL electron beam ion source with high current density electron beam

    International Nuclear Information System (INIS)

    A new electron gun with electrostatic compression has been installed at the Electron Beam Ion Source (EBIS) Test Stand at BNL. This is a collaborative effort by BNL and CERN teams with a common goal to study an EBIS with electron beam current up to 10 A, current density up to 10,000 A/cm2 and energy more than 50 keV. Intensive and pure beams of heavy highly charged ions with mass-to-charge ratio < 4.5 are requested by many heavy ion research facilities including NASA Space Radiation Laboratory (NSRL) at BNL and HIE-ISOLDE at CERN. With a multiampere electron gun, the EBIS should be capable of delivering highly charged ions for both RHIC facility applications at BNL and for ISOLDE experiments at CERN. Details of the electron gun simulations and design, and the Test EBIS electrostatic and magnetostatic structures with the new electron gun are presented. The experimental results of the electron beam transmission are given

  20. Effect of discharge current and deposition temperature on roughness and density of NbC films fabricated by ion beam sputtering technique

    Energy Technology Data Exchange (ETDEWEB)

    Dhawan, Rajnish, E-mail: rajnish@rrcat.gov.in; Rai, Sanjay, E-mail: rajnish@rrcat.gov.in; Lodha, G. S., E-mail: rajnish@rrcat.gov.in [X-ray optics Section, Indus Synchrotron Utilization Division, Raja Ramanna Center for Advanced Technology, Indore-452013 (India)

    2014-04-24

    NbC films were prepared using Ion beam sputtering system at various discharges current from 0.4 amps to 1.2 amps at room temperature. Effect of temperature on NbC films were also studied by depositing NbC films at various temperatures from room temperature to 200,300,400 and 600°C. X-ray reflectivity (XRR) study shows that surface roughness of the film decreases with decrease in discharge current. The optimum lowest roughness 3.2Å having density 92% of bulk was achieved at discharge current 0.6 amps at 3.0 cm{sup 3}/min Ar gas flow. X-ray study also shows that film roughness decreases with increase in temperature of the film and after a certain temperature it increases with increase in temperature. The lowest surface roughness 2.1Å was achieved at 300°C with density 83% of bulk NbC at constant discharge current 0.6 amps.

  1. An accurate low current measurement circuit for heavy iron beam current monitor

    International Nuclear Information System (INIS)

    Heavy-ion beams at 106 particles per second have been applied to the treatment of deep-seated inoperable tumors in the therapy terminal of the Heavy Ion Research Facility in Lanzhou (HIRFL) which is located at the Institute of Modern Physics, Chinese Academy of Sciences (IMP, CAS). An accurate low current measurement circuit following a Faraday cup was developed to monitor the beam current at pA range. The circuit consisted of a picoammeter with a bandwidth of 1 kHz and a gated integrator (GI). A low input bias current precision amplifier and new guarding and shielding techniques were used in the picoammeter circuit which allowed as to measure current less than 1 pA with a current gain of 0.22 V/pA and noise less than 10 fA. This paper will also describe a novel compensation approach which reduced the charge injection from switches in the GI to 10−18 C, and a T-switch configuration which was used to eliminate leakage current in the reset switch.

  2. Differences in the control of basal L-type Ca(2+) current by the cyclic AMP signaling cascade in frog, rat, and human cardiac myocytes.

    Science.gov (United States)

    Treinys, Rimantas; Bogdelis, Andrius; Rimkutė, Lina; Jurevičius, Jonas; Skeberdis, Vytenis Arvydas

    2016-07-01

    β-adrenergic receptors (β-ARs) mediate the positive inotropic effects of catecholamines by cAMP-dependent phosphorylation of the L-type Ca(2+) channels (LTCCs), which provide Ca(2+) for the initiation and regulation of cell contraction. The overall effect of cAMP-modulating agents on cardiac calcium current (I Ca,L) and contraction depends on the basal activity of LTCCs which, in turn, depends on the basal activities of key enzymes involved in the cAMP signaling cascade. Our current work is a comparative study demonstrating the differences in the basal activities of β-ARs, adenylyl cyclase, phosphodiesterases, phosphatases, and LTCCs in the frog and rat ventricular and human atrial myocytes. The main conclusion is that the basal I Ca,L, and consequently the contractile function of the heart, is secured from unnecessary elevation of its activity and energy consumption at the several "checking-points" of cAMP-dependent signaling cascade and the loading of these "checking-points" may vary in different species and tissues. PMID:26676115

  3. Effect of finite beam width on current separation in beam plasma system: Particle-in-Cell simulations

    CERN Document Server

    Shukla, Chandrasekhar; Patel, Kartik

    2015-01-01

    The electron beam propagation in a plasma medium is susceptible to several instabilities. In the relativistic regime typically the weibel instability leading to the current separation dominates. The linear instability analysis is carried out for a system wherein the transverse extent of the beam is infinite. Even in simulations, infinite transverse extent of the beam has been chosen. In real situations, however, beam width will always be finite. keeping this in view the role of finite beam width on the evolution of the beam plasma system has been studied here using Particle - in - Cell simulations. It is observed that the current separation between the forward and return shielding current for a beam with finite beam occurs at the scale length of the beam width itself. Consequently the magnetic field structures that form have maximum power at the scale length of the beam width. This behaviour is distinct from what happens with a beam with having an infinite extent represented by simulations in a periodic box, ...

  4. Low-energy High-current Electron Beam Generation in Plasma System and Beam-Plasma Interaction

    International Nuclear Information System (INIS)

    The review of results of experimental investigations and computer simulations of low-energy high-current electron beam generation in a low-impedance system and dynamics of beam-plasma system are given. The system includes a long plasma-filled diode, an auxiliary thermionic cathode and an explosive emission cathode. The auxiliary cathode is used to generate the a low-current, low-voltage electron beam to form long plasma anode by means of a residual gas ionisation in an external longitudinal magnetic field. The high-current low-energy electron beam is generated from the explosive emission cathode embedded in preliminary prepared plasma. Peculiarities of the system are due to: 1) the generation of electron beams with currents exceeding Alfven's limit; 2) the charge density of the beam close to the plasma density. These peculiarities complicate beam-plasma interaction significantly due to sharp non-uniform distribution of the beam current density, dominant transverse motion of the beam electrons and redistribution of ion-plasma density under the influence of fields. Computer simulation was performed using electromagnetic PIC code KARAT for different geometry's of the system

  5. Particle-in-cell simulations of electron beam control using an inductive current divider

    Science.gov (United States)

    Swanekamp, S. B.; Angus, J. R.; Cooperstein, G.; Ottinger, P. F.; Richardson, A. S.; Schumer, J. W.; Weber, B. V.

    2015-11-01

    Kinetic, time-dependent, electromagnetic, particle-in-cell simulations of the inductive current divider are presented. The inductive current divider is a passive method for controlling the trajectory of an intense, hollow electron beam using a vacuum structure that inductively splits the beam's return current. The current divider concept was proposed and studied theoretically in a previous publication [Swanekamp et al., Phys. Plasmas 22, 023107 (2015)]. A central post carries a portion of the return current (I1), while the outer conductor carries the remainder (I2) with the injected beam current given by Ib = I1 + I2. The simulations are in agreement with the theory which predicts that the total force on the beam trajectory is proportional to (I2-I1) and the force on the beam envelope is proportional to Ib. Independent control over both the current density and the beam angle at the target is possible by choosing the appropriate current-divider geometry. The root-mean-square (RMS) beam emittance (ɛRMS) varies as the beam propagates through the current divider to the target. For applications where control of the beam trajectory is desired and the current density at the target is similar to the current density at the entrance foil, there is a modest 20% increase in ɛRMS at the target. For other applications where the beam is pinched to a current density ˜5 times larger at the target, ɛRMS is 2-3 times larger at the target.

  6. Intense relativistic electron beam injector system for tokamak current drive

    International Nuclear Information System (INIS)

    We report experimental and theoretical studies of an intense relativistic electron beam (REB) injection system designed for tokamak current drive experiments. The injection system uses a standard high-voltage pulsed REB generator and a magnetically insulated transmission line (MITL) to drive an REB-accelerating diode in plasma. A series of preliminary experiments has been carried out to test the system by injecting REBs into a test chamber with preformed plasma and applied magnetic field. REBs were accelerated from two types of diodes: a conventional vacuum diode with foil anode, and a plasma diode, i.e., an REB cathode immersed in the plasma. REB current was in the range of 50 to 100 kA and REB particle energy ranged from 0.1 to 1.0 MeV. MITL power density exceeded 10 GW/cm2. Performance of the injection system and REB transport properties is documented for plasma densities from 5 x 1012 to 2 x 1014 cm-3. Injection system data are compared with numerical calculations of the performance of the coupled system consisting of the generator, MITL, and diode

  7. Electro-static beam steering mechanism for a high current negative ion beam consisting of multi-beamlets

    International Nuclear Information System (INIS)

    An electrostatic beam steering mechanism (ESM) has been designed and tested to deflect negative ion beams consisting of multi-beamlets. A steering angle of 10 mrad was obtained within the deviation of less than 1 mrad by biasing two electrodes at 0.5 kV and -0.75 kV for 120 keV H- ion beam. The current flowing to the positive electrode was no more than 10% of the beam current at a pressure of 2.8x10-5 Torr. (author)

  8. Development of a highly sensitive beam current monitor with a SQUID and superconducting magnetic shield

    International Nuclear Information System (INIS)

    Beam diagnostics are an essential constituent of any accelerator. There are a large variety of beam parameters, and total current is one of the most important parameters for accelerators. A current monitor is used to operate an accelerator efficiently and to improve the performance of the machine. A Faraday cup is the most fundamental current detection process, in which charged particles are stopped in the cup. However, this destructive method cannot be applied for high-current or high-energy beams because the total energy carried by the beam can destroy and activate the intercepting material. Therefore, non-destructive beam current measurement requires the use of current transformers that detect the magnetic field produced by the pulsed or DC beam. On the other hand, a new type of beam current monitor using a low-temperature superconducting (LTS) magnetic shield and an LTS SQUID was developed to measure the faint ion beams that are below the lowest measurable limit of the DC current transformer (DCCT) for atomic-physics studies. Recently, a prototype of a highly sensitive SQUID current monitor for measuring the intensity of faint beams, such as radioisotope beams, was completed for the RIKEN RI beam factory. This monitor is composed of a high-temperature superconducting (HTS) magnetic shield and an HTS SQUID. The first measurements using ion beams were carried out in the CNS experimental hall and RIKEN Ring Cyclotron (RRC). This paper first describes the principle of the conventional current monitor such as the Faraday cup and current transformers. Second, the progress of the LTS SQUID current monitor is discussed, and finally, the present status of the prototype of the LTS SQUID current monitor is discussed, and finally, the present status of the prototype of the HTS SQUID current monitor at RIKEN and the results of the first beam measurement are given. (author)

  9. Cryogenic Current Comparator as Low Intensity Beam Current Monitor in the CERN Antiproton Decelerators

    CERN Document Server

    Fernandes, M; Soby, L; Welsch, CP

    2013-01-01

    In the low-energy Antiproton Decelerator (AD) and the future Extra Low ENergy Antiproton (ELENA) rings at CERN, an absolute measurement of the beam intensity is essential to monitor any losses during the deceleration and cooling phases. However, existing DC current transformers can hardly reach the μA level, while at the AD and ELENA currents can be as low as 100 nA. A Cryogenic Current Comparator (CCC) based on a superconducting quantum interference device (SQUID) is currently being designed and shall be installed in the AD and ELENA machines. It should meet the following specifications: A current resolution smaller than 10 nA, a dynamic range covering currents between 100 nA and 1 mA, as well as a bandwidth from DC to 1 kHz. Different design options are being considered, including the use of low or high temperature superconductor materials, different CCC shapes and dimensions, different SQUID characteristics, as well as electromagnetic shielding requirements. In this contribution we present first results f...

  10. Experimental Verification of Current Shear Design Equations for HSRC Beams

    Directory of Open Access Journals (Sweden)

    Attaullah Shah

    2012-07-01

    Full Text Available Experimental research on the shear capacity of HSRC (High Strength Reinforced Concrete beams is relatively very limited as compared to the NSRC (Normal Strength Reinforced Concrete beams. Most of the Building Codes determine the shear strength of HSRC with the help of empirical equations based on experimental work of NSRC beams and hence these equations are generally regarded as un-conservative for HSRC beams particularly at low level of longitudinal reinforcement. In this paper, 42 beams have been tested in two sets, such that in 21 beams no transverse reinforcement has been used, whereas in the remaining 21 beams, minimum transverse reinforcement has been used as per ACI-318 (American Concrete Institute provisions. Two values of compressive strength 52 and 61 MPa, three values of longitudinal steel ratio and seven values of shear span to depth ratio have been have been used. The beams were tested under concentrated load at the mid span. The results are compared with the equations proposed by different international building codes like ACI, AASHTO LRFD, EC (Euro Code, Canadian Code and Japanese Code for shear strength of HSRC beams.From comparison, it has been observed that some codes are less conservative for shear design of HSRC beams and further research is required to rationalize these equations.

  11. Development of capacitive beam position, beam current and Schottky-signal monitors for the Cryogenic Storage Ring (CSR)

    International Nuclear Information System (INIS)

    In this thesis novel techniques based on capacitive pickups for the determination of the beam current, the beam position and the Schottky-signal in storage rings have been developed. Beam current measurements at the heavy ion storage ring TSR with a capacitive pickup have been found in very good agreement with the theory. Using this device the accurate measurement of beam currents at the TSR far below 1 μA is now possible. This method will also be used at the Cryogenic Storage Ring (CSR) at which beam currents in the range of 1 nA-1 μA are expected. For the first time, position measurements with a resonant amplifier system for capacitive pickups have been examined at the TSR for later use of this technique in the CSR. With this method an increased signal-to-noise ratio can be achieved using a parallel inductance. A comparison with measurements using the rest gas beam profile monitor has shown very good agreement even at very low intensities. Experiments with the cryo-capable electronics for the CSR beam position monitors have shown an achievable quality factor of Q=500, resulting in the prospect of precise position measurements at the CSR even at very low beam currents. The CSR Schottky-Pickup will also be equipped with a resonant amplifier system with a comparable quality factor. An estimation of the signal-to-noise ratio suggests a detection limit of a few protons. (orig.)

  12. Improvements of a Beam Current Monitor by using a High Tc Current Sensor and SQUID at the RIBF

    Science.gov (United States)

    Watanabe, T.; Fukunishi, N.; Kase, M.; Kamigaito, O.; Inamori, S.; Kon, K.

    2014-05-01

    To measure a beam current non-destructively, a conventional DC current transformer (DCCT) has been used at accelerator facilities. However, the current resolution of the DCCT is worse than 1μA. This current resolution is sufficient for electron and proton accelerators in which the beam intensity is high, but it is not sufficient for lower intensity heavy-ion beams. Thus, superconducting technology has been applied to the precise measurement of the beam current. In particular, to measure the DC current of high-energy heavy-ion beams non-destructively at high resolution, a high critical temperature (HTc) superconducting quantum interference device (SQUID) beam current monitor (HTc SQUID monitor) has been developed for use in the radioactive isotope beam factory (RIBF) at RIKEN in Japan. Beginning this year, the magnetic shielding system has been greatly reinforced. The measurement resolution is determined by the signal to noise ratio, that is improved by attenuating the external magnetic noise and is mainly produced by the distribution and transmission lines from the high current power supplies. The new strong magnetic shielding system can attenuate the external magnetic noise to 10-10.

  13. Improvements of a beam current monitor by using a high Tc current sensor and SQUID at the RIBF

    International Nuclear Information System (INIS)

    To measure a beam current non-destructively, a conventional DC current transformer (DCCT) has been used at accelerator facilities. However, the current resolution of the DCCT is worse than 1μA. This current resolution is sufficient for electron and proton accelerators in which the beam intensity is high, but it is not sufficient for lower intensity heavy-ion beams. Thus, superconducting technology has been applied to the precise measurement of the beam current. In particular, to measure the DC current of high-energy heavy-ion beams non-destructively at high resolution, a high critical temperature (HTc) superconducting quantum interference device (SQUID) beam current monitor (HTc SQUID monitor) has been developed for use in the radioactive isotope beam factory (RIBF) at RIKEN in Japan. Beginning this year, the magnetic shielding system has been greatly reinforced. The measurement resolution is determined by the signal to noise ratio, that is improved by attenuating the external magnetic noise and is mainly produced by the distribution and transmission lines from the high current power supplies. The new strong magnetic shielding system can attenuate the external magnetic noise to 10−10.

  14. Filtered neutron beams at the FMRB - review and current status

    International Nuclear Information System (INIS)

    A review is presented of our experience with filtered neutron beams installed in beam tubes of the Research and Measurement Reactor Braunschweig since 1976: Desing of the filters and measurement of the beam parameters are reported and an outline of the research work done with the beams is given. The present status of the irradiation facility, which consists of 5 beams (144 keV, 24.5 keV, 2 keV, 0.2 keV and thermal neutrons), is described in some detail to allow understanding of the physical as well as the technical prerequisites for performing calibrations of neutron measuring instruments. An appendix contains the actual beam parameters. (orig.)

  15. Resistive wall heating due to image current on the beam chamber for a superconducting undulator.

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S. H. (Accelerator Systems Division (APS))

    2012-03-27

    The image-current heating on the resistive beam chamber of a superconducting undulator (SCU) was calculated based on the normal and anomalous skin effects. Using the bulk resistivity of copper for the beam chamber, the heat loads were calculated for the residual resistivity ratios (RRRs) of unity at room temperature to 100 K at a cryogenic temperature as the reference. Then, using the resistivity of the specific aluminum alloy 6053-T5, which will be used for the SCU beam chamber, the heat loads were calculated. An electron beam stored in a storage ring induces an image current on the inner conducting wall, mainly within a skin depth, of the beam chamber. The image current, with opposite charge to the electron beam, travels along the chamber wall in the same direction as the electron beam. The average current in the storage ring consists of a number of bunches. When the pattern of the bunched beam is repeated according to the rf frequency, the beam current may be expressed in terms of a Fourier series. The time structure of the image current is assumed to be the same as that of the beam current. For a given resistivity of the chamber inner wall, the application ofthe normal or anomalous skin effect will depend on the harmonic numbers of the Fourier series of the beam current and the temperature of the chamber. For a round beam chamber with a ratius r, much larger than the beam size, one can assume that the image current density as well as the density square, may be uniform around the perimeter 2{pi}r. For the SCU beam chamber, which has a relatively narrow vertical gap compared to the width, the effective perimeter was estimated since the heat load should be proportional to the inverse of the perimeter.

  16. Controlling hollow relativistic electron beam orbits with an inductive current divider

    Energy Technology Data Exchange (ETDEWEB)

    Swanekamp, S. B.; Richardson, A. S.; Angus, J. R.; Cooperstein, G.; Hinshelwood, D. D.; Ottinger, P. F.; Rittersdorf, I. M.; Schumer, J. W.; Weber, B. V.; Zier, J. C. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States)

    2015-02-15

    A passive method for controlling the trajectory of an intense, hollow electron beam is proposed using a vacuum structure that inductively splits the beam's return current. A central post carries a portion of the return current (I{sub 1}), while the outer conductor carries the remainder (I{sub 2}). An envelope equation appropriate for a hollow electron beam is derived and applied to the current divider. The force on the beam trajectory is shown to be proportional to (I{sub 2}-I{sub 1}), while the average force on the envelope (the beam width) is proportional to the beam current I{sub b} = (I{sub 2} + I{sub 1}). The values of I{sub 1} and I{sub 2} depend on the inductances in the return-current path geometries. Proper choice of the return-current geometries determines these inductances and offers control over the beam trajectory. Solutions using realistic beam parameters show that, for appropriate choices of the return-current-path geometry, the inductive current divider can produce a beam that is both pinched and straightened so that it approaches a target at near-normal incidence with a beam diameter that is on the order of a few mm.

  17. Spontaneous short-wave radiation of high-current electron beam

    International Nuclear Information System (INIS)

    Angular and spectral characteristics of spontaneous radiation of high-current electron beam in a proper magnetic field are theoretically investigated. The model of a cylindrically- symmetric non rotating stationary beam the space charge of which is completely compensated by a motionless ion background has been used. It is shown that the radiation considerably depends on the beam current, its directivity with current increase drops, total intensity grows, but the spectrum widens

  18. Heavy ion linac as a high current proton beam injector

    Science.gov (United States)

    Barth, Winfried; Adonin, Aleksey; Appel, Sabrina; Gerhard, Peter; Heilmann, Manuel; Heymach, Frank; Hollinger, Ralph; Vinzenz, Wolfgang; Vormann, Hartmut; Yaramyshev, Stepan

    2015-05-01

    A significant part of the experimental program at Facility for Antiproton and Ion Research (FAIR) is dedicated to pbar physics requiring a high number of cooled pbars per hour. The primary proton beam has to be provided by a 70 MeV proton linac followed by two synchrotrons. The new FAIR proton linac will deliver a pulsed proton beam of up to 35 mA of 36 μ s duration at a repetition rate of 4 Hz (maximum). The GSI heavy ion linac (UNILAC) is able to deliver world record uranium beam intensities for injection into the synchrotrons, but it is not suitable for FAIR relevant proton beam operation. In an advanced machine investigation program it could be shown that the UNILAC is able to provide for sufficient high intensities of CH3 beam, cracked (and stripped) in a supersonic nitrogen gas jet into protons and carbon ions. This advanced operational approach will result in up to 3 mA of proton intensity at a maximum beam energy of 20 MeV, 1 0 0 μ s pulse duration and a repetition rate of up to 2.7 Hz delivered to the synchrotron SIS18. Recent linac beam measurements will be presented, showing that the UNILAC is able to serve as a proton FAIR injector for the first time, while the performance is limited to 25% of the FAIR requirements.

  19. Fast-ion transport and neutral beam current drive in ASDEX upgrade

    DEFF Research Database (Denmark)

    Geiger, B.; Weiland, M.; Jacobsen, Asger Schou;

    2015-01-01

    The neutral beam current drive efficiency has been investigated in the ASDEX Upgrade tokamak by replacing on-axis neutral beams with tangential off-axis beams. A clear modification of the radial fast-ion profiles is observed with a fast-ion D-alpha diagnostic that measures centrally peaked profil...

  20. Evolution of ring current formed by relativistic electron beam injection into a charge but not current neutralizing plasma

    International Nuclear Information System (INIS)

    The time evolutions of the azimuthal momentum distribution of the axisymmetrically injected electrons and the resulting ring current are self-consistently analyzed under the assumption that no return current is induced in the background plasma. It is shown that the ring current grows linearly with time for a characteristic time from the start of beam injection, and afterthere it tends to saturate at some level. The dependence of the time evolution of the ring current on the beam energy at injection and on the injection current is also obtained. (author)

  1. Particle-in-cell simulations of electron beam control using an inductive current divider

    Energy Technology Data Exchange (ETDEWEB)

    Swanekamp, S. B.; Angus, J. R.; Cooperstein, G.; Ottinger, P. F.; Richardson, A. S.; Schumer, J. W.; Weber, B. V. [Plasma Physics Division, Naval Research Laboratory, Washington, District of Columbia 20375 (United States)

    2015-11-15

    Kinetic, time-dependent, electromagnetic, particle-in-cell simulations of the inductive current divider are presented. The inductive current divider is a passive method for controlling the trajectory of an intense, hollow electron beam using a vacuum structure that inductively splits the beam's return current. The current divider concept was proposed and studied theoretically in a previous publication [Swanekamp et al., Phys. Plasmas 22, 023107 (2015)]. A central post carries a portion of the return current (I{sub 1}), while the outer conductor carries the remainder (I{sub 2}) with the injected beam current given by I{sub b} = I{sub 1} + I{sub 2}. The simulations are in agreement with the theory which predicts that the total force on the beam trajectory is proportional to (I{sub 2}−I{sub 1}) and the force on the beam envelope is proportional to I{sub b}. Independent control over both the current density and the beam angle at the target is possible by choosing the appropriate current-divider geometry. The root-mean-square (RMS) beam emittance (ε{sub RMS}) varies as the beam propagates through the current divider to the target. For applications where control of the beam trajectory is desired and the current density at the target is similar to the current density at the entrance foil, there is a modest 20% increase in ε{sub RMS} at the target. For other applications where the beam is pinched to a current density ∼5 times larger at the target, ε{sub RMS} is 2–3 times larger at the target.

  2. Numerical simulation of high-current ion linear induction accelerator with additional electron beam injection

    International Nuclear Information System (INIS)

    The 2d3v particle-in-cell simulations of the transportation and acceleration of a high-current tubular ion beam through six magnetoinsulated accelerating gaps are presented. Charge and current compensations are carried out by an accompanying electron beam, and also by additionally injected electron beams. The accelerating electric field is enclosed to the first, third and fifth cusps. Its magnitudes are those, that initial kinetic energy of compensating electron beams is little bit higher than a potential barrier of an accelerating field in each cusp, that allows an electron beam to overcome accelerating potential in one cusp. The second, fourth and sixth cusps in which the accelerating field is absent, are used for injection of additional compensating electron beams which replace the electron beam which has 'worked-out' on the previous accelerating gap. The simulations involve solving a complete set of Maxwell's equations with charge-conserving scheme for calculating the current density on a mesh, and relativistic motion equations for charged particles. The possibility of transporting and acceleration of a high-current tubular ion beam in six cusps is shown. It is shown, that distribution function of a high-current ion beam on an output of the accelerator essentially improves due to optimization of parameters of additionally injected electron beams.

  3. Dependence of EC-driven current on the EC-wave beam direction in LHD

    International Nuclear Information System (INIS)

    Electron cyclotron current drive (ECCD) experiments were conducted in the Large Helical Device to investigate the characteristics of EC-driven current and its profile and the possibility of controlling current and rotational transform profiles by ECCD. Successful ECCD helps prevent magnetohydrodynamic instabilities in plasmas. Scanning the EC-wave beam direction with a long pulse width of 8 s revealed a systematic change in the plasma current. The current's direction was reversed by a reversal of the beam direction. The direction agrees with the prediction of Fisch-Boozer theory regarding EC-wave beam injection from low-field side. The maximum driven current is 9 kA with an EC-wave power of 100 kW. The optimum beam direction that maximizes the driven current is investigated with the help of ray-tracing code. This direction depends on the magnetic field, efficiency of power absorption, and fraction of the power absorbed by trapped electrons. (author)

  4. Automated pinhole-aperture diagnostic for the current profiling of TWT electron beams

    International Nuclear Information System (INIS)

    The measurement system reported here is intended for use in determining the current density distribution of electron beams from Pierce guns for use in TWTs. The system was designed to automatically scan the cross section of the electron beam and collect the high-resolution data with a Faraday cup probe mounted on a multistage manipulator using the LabVIEW program. A 0.06 mm thick molybdenum plate with a pinhole and a Faraday cup mounted as a probe assembly was employed to sample the electron beam current with 0.5 µm space resolution. The thermal analysis of the probe with pulse beam heating was discussed. A 0.45 µP electron gun with the expected minimum beam radius 0.42 mm was measured and the three-dimensional current density distribution, beam envelope and phase space were presented. (paper)

  5. High precision electron beam diagnostic system for high current long pulse beams

    International Nuclear Information System (INIS)

    As part of the effort to develop a multi-axis electron beam transport system using stripline kicker technology for DARHT II applications, it is necessary to precisely determine the position and extent of long high energy beams (6-40 MeV, 1-4 kA, 2 microseconds) for accurate position control. The kicker positioning system utilizes shot-to-shot adjustments for reduction of relatively slow (<20 MHz) motion of the beam centroid. The electron beams passing through the diagnostic systems have the potential for large halo effects that tend to corrupt measurements performed using capacitive pick-off probes. Likewise, transmission line traveling wave probes have problems with multi-bounce effects due to these longer pulse widths. Finally, the high energy densities experienced in these applications distort typical foil beam position measurements

  6. Current status of electron beam processing system and its applications

    International Nuclear Information System (INIS)

    The feature and application fields of electron beam processing systems (EPS), the selection of machine ratings and safety measures for EPS are described. EPS has the various features: a) Chemical reactions occurs independent of the temperature, b) it occurs without any added substances such as catalysts, c) mass productivity, d) easy operation, as is exemplified by switch ON and OFF, and e) easy maintenance, compared with radioisotope sources. After briefly explaining acceleration type (DC or AC), power supply (Van-de-Graaf or Cockcroft-walton and others), beam scanning to be used for large area irradiation, and some typical applications (cross-linking, radical polymerization, the paper describes necessary safety measures such as X-ray shielding, ozone control including ozone generation and its disposal, interlock system, warning buzzer, and monitoring and measuring. (S. Ohno)

  7. A new method of rapid power measurement for MW-scale high-current particle beams

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yongjian, E-mail: yjxu@ipp.ac.cn; Hu, Chundong; Xie, Yuanlai; Liu, Zhimin; Xie, Yahong; Liu, Sheng; Liang, Lizheng; Jiang, Caichao; Sheng, Peng; Yu, Ling

    2015-09-21

    MW-scale high current particle beams are widely applied for plasma heating in the magnetic confinement fusion devices, in which beam power is an important indicator for efficient heating. Generally, power measurement of MW-scale high current particle beam adopts water flow calorimetry (WFC). Limited by the principles of WFC, the beam power given by WFC is an averaged value. In this article a new method of beam power for MW-scale high-current particle beams is introduced: (1) the temperature data of thermocouples embedded in the beam stopping elements were obtained using high data acquire system, (2) the surface heat flux of the beam stopping elements are calculated using heat transfer, (3) the relationships between positions and heat flux were acquired using numerical simulation, (4) the real-time power deposited on the beam stopping elements can be calculated using surface integral. The principle of measurement was described in detail and applied to the EAST neutral beam injector for demonstration. The result is compared with that measured by WFC. Comparison of the results shows good accuracy and applicability of this measuring method.

  8. A new method of rapid power measurement for MW-scale high-current particle beams

    Science.gov (United States)

    Xu, Yongjian; Hu, Chundong; Xie, Yuanlai; Liu, Zhimin; Xie, Yahong; Liu, Sheng; Liang, Lizheng; Jiang, Caichao; Sheng, Peng; Yu, Ling

    2015-09-01

    MW-scale high current particle beams are widely applied for plasma heating in the magnetic confinement fusion devices, in which beam power is an important indicator for efficient heating. Generally, power measurement of MW-scale high current particle beam adopts water flow calorimetry (WFC). Limited by the principles of WFC, the beam power given by WFC is an averaged value. In this article a new method of beam power for MW-scale high-current particle beams is introduced: (1) the temperature data of thermocouples embedded in the beam stopping elements were obtained using high data acquire system, (2) the surface heat flux of the beam stopping elements are calculated using heat transfer, (3) the relationships between positions and heat flux were acquired using numerical simulation, (4) the real-time power deposited on the beam stopping elements can be calculated using surface integral. The principle of measurement was described in detail and applied to the EAST neutral beam injector for demonstration. The result is compared with that measured by WFC. Comparison of the results shows good accuracy and applicability of this measuring method.

  9. Beam instability during high-current heavy-ion beam transport

    International Nuclear Information System (INIS)

    In driver system for heavy ion inertial fusion, beam dynamics is investigated by particle-in-cell simulations during final beam bunching. The particle simulations predict that the beam is transported with the localized transverse charge distribution induced by the strong space charge effect. The calculation results also show that the emittance growth during the longitudinal bunch compression for various particle distributions at the initial conditions and with two types of transverse focusing model, which are a continuous focusing and an alternating gradient focusing lattice configurations. (author)

  10. Activation of µ-opioid receptors inhibits calcium-currents in the vestibular afferent neurons of the rat through a cAMP dependent mechanism

    Directory of Open Access Journals (Sweden)

    Enrique Soto

    2014-03-01

    Full Text Available Opioid receptors are expressed in the vestibular endorgans (afferent neurons and hair cells and are activated by the efferent system, which modulates the discharge of action potentials in the vestibular afferent neurons (VANs. In mammals, the VANs mainly express the µ opioid-receptor, but the function of the opioid receptor activation and the cellular mechanisms by which they exert their actions in these neurons are poorly studied. To determine the actions of the µ opioid receptor (MOR and the cell signaling mechanisms in the VANs, we made perforated patch-clamp recordings of VANs that were obtained from postnatal days 7 to 10 (P7-10 rats and then maintained in primary culture. The MOR agonist [D-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin (DAMGO inhibited the total voltage-gated outward current; this effect was prevented by the perfusion of a Ca2+-free extracellular solution. We then studied the voltage-gated calcium current (Ica and found that DAMGO Met-enkephalin or endomorphine-1 inhibited the ICa in a dose-response fashion. The effects of DAMGO were prevented by the MOR antagonist (CTAP or by the pertussis toxin (PTX. The use of specific calcium channel blockers showed that MOR activation inhibited the T-, L- and N-type ICa. The use of various enzyme activators and inhibitors and of cAMP analogs allowed us to demonstrate that the MOR acts through a cAMP dependent signaling mechanism. In the current clamp experiments, MOR activation increased the duration and decreased the amplitude of the action potentials and modulated the discharge to the current injection. Pre-incubation with PTX occluded all MOR activation effects observed in the current clamp experiments.\tWe conclude that MOR activation inhibits the T-, L- and N-type ICa through the activation of a Gi/o protein that involves a decrease in AC-cAMP-PKA activity. The modulation of ICa may have an impact on the synaptic integration, excitability and neurotransmitter release from the VANs.

  11. Transport and Measurements of High-Current Electron Beams from X pinches

    Science.gov (United States)

    Agafonov, Alexey V.; Mingaleev, Albert R.; Romanova, Vera M.; Tarakanov, Vladimir P.; Shelkovenko, Tatiana A.; Pikuz, Sergey A.; Blesener, Isaac C.; Kusse, Bruce R.; Hammer, David A.

    2009-01-01

    Generation of electron beams is an unavoidable property of X-pinches and other pulsed-power-driven pinches of different geometry. Some issues concerning high-current electron beam transport from the X pinch to the diagnostic system and measurements of the beam current by Faraday cups with different geometry's are discussed. Of particular interest is the partially neutralized nature of the beam propagating from the X-pinch to a diagnostic system. Two scenarios of electron beam propagation from X-pinch to Faraday cup are analyzed by means of computer simulation using the PIC-code KARAT. The first is longitudinal neutralization by ions extracted from plasma at an output window of the X-pinch diode; the second is the beam transport through a plasma background between the diode and a diagnostic system.

  12. Transport and Measurements of High-Current Electron Beams from X pinches

    International Nuclear Information System (INIS)

    Generation of electron beams is an unavoidable property of X-pinches and other pulsed-power-driven pinches of different geometry. Some issues concerning high-current electron beam transport from the X pinch to the diagnostic system and measurements of the beam current by Faraday cups with different geometry's are discussed. Of particular interest is the partially neutralized nature of the beam propagating from the X-pinch to a diagnostic system. Two scenarios of electron beam propagation from X-pinch to Faraday cup are analyzed by means of computer simulation using the PIC-code KARAT. The first is longitudinal neutralization by ions extracted from plasma at an output window of the X-pinch diode; the second is the beam transport through a plasma background between the diode and a diagnostic system.

  13. Augmentation of beam currents in the JAERI tandem-booster accelerator facility

    Energy Technology Data Exchange (ETDEWEB)

    Takeuchi, Suehiro; Matsuda, Makoto; Yoshida, Tadashi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-02-01

    Modifications have been executed in these years of the accelerator system, aiming at higher beam currents. Advanced experiments e.g. search of unknown heavy nuclei and their synthesis, need large current accelerators. The use of stripper foils in tandem accelerators for the electron detachment severely limits the beam current, however. The first modification is to install ECR (electron cyclotron resonance) ion source in a high voltage terminal board, multicharged, rare gas ions being accelerated directly. The second is to eliminate the use of the second foils, but to increase the beam intensity. (M. Tanaka)

  14. A 128-channel picoammeter system and its application on charged particle beam current distribution measurements

    International Nuclear Information System (INIS)

    A 128-channel picoammeter system is constructed based on instrumentation amplifiers. Taking advantage of a high electric potential and narrow bandwidth in DC energetic charged beam measurements, a current resolution better than 5 fA can be achieved. Two sets of 128-channel strip electrodes are implemented on printed circuit boards and are employed for ion and electron beam current distribution measurements. Tests with 60 keV O3+ ions and 2 keV electrons show that it can provide exact boundaries when a positive charged particle beam current distribution is measured

  15. A 128-channel picoammeter system and its application on charged particle beam current distribution measurements

    Science.gov (United States)

    Yu, Deyang; Liu, Junliang; Xue, Yingli; Zhang, Mingwu; Cai, Xiaohong; Hu, Jianjun; Dong, Jinmei; Li, Xin

    2015-11-01

    A 128-channel picoammeter system is constructed based on instrumentation amplifiers. Taking advantage of a high electric potential and narrow bandwidth in DC energetic charged beam measurements, a current resolution better than 5 fA can be achieved. Two sets of 128-channel strip electrodes are implemented on printed circuit boards and are employed for ion and electron beam current distribution measurements. Tests with 60 keV O3+ ions and 2 keV electrons show that it can provide exact boundaries when a positive charged particle beam current distribution is measured.

  16. A 128-channel picoammeter system and its application on charged particle beam current distribution measurements

    CERN Document Server

    Yu, Deyang; Xue, Yingli; Zhang, Mingwu; Cai, Xiaohong; Hu, Jianjun; Dong, Jinmei; Li, Xin

    2015-01-01

    A 128-channel picoammeter system is constructed based on instrumentation amplifiers. Taking the advantages of high electric potential and narrow bandwidth in DC energetic charged beam measurements, current resolution better than 5 fA can be achieved. Two 128-channel Faraday cup arrays are built, and are employed for ion and electron beam current distribution measurements. Tests with 60 keV O3+ ions and 2 keV electrons show that it can provide exact boundaries when a positive charged particle beam current distribution is measured.

  17. Drift distance survey in direct plasma injection scheme for high current beam production

    International Nuclear Information System (INIS)

    In a laser ion source, plasma drift distance is one of the most important design parameters. Ion current density and beam pulse width are defined by plasma drift distance between a laser target and beam extraction position. In direct plasma injection scheme, which uses a laser ion source and a radio frequency quadrupole linac, we can apply relatively higher electric field at beam extraction due to the unique shape of a positively biased electrode. However, when we aim at very high current acceleration such as several tens of milliamperes, we observed mismatched beam extraction conditions. We tested three different ion current at ion extraction region by changing plasma drift distance to study better extraction condition. In this experiment, C6+ beam was accelerated. We confirmed that matching condition can be improved by controlling plasma drift distance.

  18. Effects of beam-driven poloidal rotation on the neoclassical bootstrap current

    International Nuclear Information System (INIS)

    Unbalanced neutral beam injection drives toroidal and poloidal rotations in a tokamak plasma. The beam toroidal momentum input drives the toroidal rotation, and the parallel friction between the thermal ions and fast ions induces the poloidal rotation. A theory of the beam-driven poloidal rotation and its effects on energy transport was given recently by Hinton and Kim. In this work, we extend their considerations to the effects on the neoclassical bootstrap current. For parameters of interest in present neutral beam heated tokamaks, the magnitude of the beam-driven poloidal rotation can be significantly larger than that of the standard neoclassical value due to the ion temperature gradient. The presence of this driven poloidal rotation will manifest itself in modification of the neoclassical bootstrap current. In the case of coinjection, the driven poloidal rotation is in the opposite direction to the rotation driven by the temperature gradient, therefore it enhances the bootstrap current. In comparison with the standard theoretical predictions of the neutral beam-driven current, that enhancement in the bootstrap current varies with the beam and plasma parameters. A calculation of the parallel transport coefficients associated with the driven poloidal flow in finite-aspect ratio tokamaks will be presented. Experimental conditions for observing the enhancement in bootstrap current will be discussed

  19. Amplification of relativistic electron beam current propagating in ambient neutral gases

    International Nuclear Information System (INIS)

    It is experimentally observed that the net current is more than the primary beam current when the relativistic electron beam (REB) is propagated in ambient neutral gases (H2, He, air) at subtorr pressures (0.1-0.3 torr). Chambers attempted to explain the current amplification via the two-stream instability under the assumption of an ultrarelativistic, one-dimensional cold beam, limiting its applicability to specific situations. The authors have derived the current gain (G) expression in general for a scattered REB propagating in a neutral gas by taking into account a quasi-hydrodynamic expression for the beam energy loss. Moreover, the beam-to-plasma density ratio nb/nrho as a function of time is obtained for a given beam pulse by solving the electron energy and continuity equations numerically. It is found that at a given nb/nrho the current gain increases with increasing the beam energy, increases being rapid for the small average scattering angles. A finite average scattering angle is seen to reduce the current amplification

  20. Numerical Simulation of Non-Inductive Current Driven Scenario in EAST Using Neutral Beam Injection

    Science.gov (United States)

    Li, Hao; Wu, Bin; Wang, Jinfang; Wang, Ji; Hu, Chundong

    2015-01-01

    For achieving the scientific mission of long pulse and high performance operation, experimental advanced superconducting tokamak (EAST) applies fully superconducting magnet technology and is equiped with high power auxiliary heating system. Besides RF (Radio Frequency) wave heating, neutral beam injection (NBI) is an effective heating and current drive method in fusion research. NBCD (Neutral Beam Current Drive) as a viable non-inductive current drive source plays an important role in quasi-steady state operating scenario for tokamak. The non-inductive current driven scenario in EAST only by NBI is predicted using the TSC/NUBEAM code. At the condition of low plasma current and moderate plasma density, neutral beam injection heats the plasma effectively and NBCD plus bootstrap current accounts for a large proportion among the total plasma current for the flattop time.

  1. Influence of total beam current on HRTEM image resolution in differentially pumped ETEM with nitrogen gas

    International Nuclear Information System (INIS)

    Environmental transmission electron microscopy (ETEM) enables the study of catalytic and other reaction processes as they occur with Angstrom-level resolution. The microscope used is a dedicated ETEM (Titan ETEM, FEI Company) with a differential pumping vacuum system and apertures, allowing aberration corrected high-resolution transmission electron microscopy (HRTEM) imaging to be performed with gas pressures up to 20 mbar in the sample area and with significant advantages over membrane-type E-cell holders. The effect on image resolution of varying the nitrogen gas pressure, electron beam current density and total beam current were measured using information limit (Young's fringes) on a standard cross grating sample and from silicon crystal lattice imaging. As expected, increasing gas pressure causes a decrease in HRTEM image resolution. However, the total electron beam current also causes big changes in the image resolution (lower beam current giving better resolution), whereas varying the beam current density has almost no effect on resolution, a result that has not been reported previously. This behavior is seen even with zero-loss filtered imaging, which we believe shows that the drop in resolution is caused by elastic scattering at gas ions created by the incident electron beam. Suitable conditions for acquiring high resolution images in a gas environment are discussed. Lattice images at nitrogen pressures up to 16 mbar are shown, with 0.12 nm information transfer at 4 mbar. -- Highlights: ► ETEM images with point resolution of 0.12 nm in 4 mbar of nitrogen gas. ► Clear Si lattice imaging with 16 mbar of nitrogen gas. ► ETEM image resolution in gas can be much improved by decreasing total beam current. ► Beam current density (beam convergence) has no effect on the image resolution.

  2. On the effect of the inductive self-acceleration of heavy-current electron beam

    International Nuclear Information System (INIS)

    The possibility of existing the effect of the electron beam inductive self-acceleration by its reset on the thick diaphragm with a small opening is studied. The computer modeling of the dynamics of the heavy-current relativistic electron beam reset on the thick diaphragm with openings is carried out. The modeled structure constitutes the heavy-current vacuum electron diode with and annular cathode and thick diaphragm with a thin annular opening. The results on modeling the 3 mm opening width, 8 mm diaphragm thickness and 5 kA beam current are presented. The computer modeling results prove the possibility of existence of the effect of the heavy-current electron beam inductive self-acceleration by its transmission through the thick diaphragm with an opening

  3. Simulation of Electron Beam Dynamics in a Nonmagnetized High-Current Vacuum Diode

    CERN Document Server

    Anishchenko, Sergey

    2016-01-01

    The electron beam dynamics in a nonmagnetized high-current vacuum diode is analyzed for different cathode-anode gap geometries. The conditions enabling to achieve the minimal {initial} momentum spread in the electron beam are found out. A drastic rise of current density in a vacuum diode with a ring-type cathode is described. The effect is shown to be caused by electrostatic repulsion.

  4. Electron heating, time evolution of bremsstrahlung and ion beam current in electron cyclotron resonance ion sources

    OpenAIRE

    Ropponen, Tommi

    2010-01-01

    This thesis is a study of Electron Cyclotron Resonance Ion Source (ECRIS) plasmas and their properties. The focus has been on time evolution studies of bremsstrahlung emission, ion beam current production and numerical studies of electron heating in ECRIS plasmas. The time scales for reaching steady state bremsstrahlung production at electron energies greater than 30 keV is shown to be on the order of several hundreds of milliseconds. The ion beam currents of different elements...

  5. Diagnostics and electron-optics of a high current electron beam in the TANDEM free electron laser - status report

    International Nuclear Information System (INIS)

    In the construction of the Israeli TANDEM FEL the major task is to develop a high quality electron optic system. The goal is to focus the e-beam to a minimal radius (1 mm) in the interaction region (the wiggler). Furthermore, good focusing throughout the accelerator is essential in order to achieve high transport efficiency avoiding discharge and voltage drop of the high voltage terminal. We have completed the electron optical design and component procurement, including 8 quadrupole lenses 4 steering coils and an electrostatic control system. All are being assembled into the high voltage terminal and controlled by a fiber optic link. Diagnostic means based on fluorescent screens and compact CCD camera cards placed at the HV terminal and at the end of the e-gun injector have been developed. We report first measurements of the beam emittance at the entrance to the Tandem accelerator tube using the open-quote pepper pot close-quote technique. The experiment consists of passing the 0.5 Amp beam through a thin plate which is perforated with an army of 0.5 mm holes. The spots produced on a fluorescent screen placed 90 cm from the pepper pot were recorded with a CCD camera and a frame grabber. The measured normalized emittance is lower than 10π mm mR which is quite close to the technical limit of dispenser cathode e-guns of the kind we have. Recent results of the measured transport efficiency and the diagnostics of the high current (1A, 1.5MV) electron-optical system will be reported

  6. Role of the rise rate of beam current in the microwave radiation of vircator

    Science.gov (United States)

    Li, Limin; Cheng, Guoxin; Zhang, Le; Ji, Xiang; Chang, Lei; Xu, Qifu; Liu, Lie; Wen, Jianchun; Li, Chuanlu; Wan, Hong

    2011-04-01

    In this paper, the effect of the rise rate of beam current on the microwave radiation of a virtual cathode oscillator (vircator) is presented. Interestingly, it was observed that the rise rate of the beam current increased as the pulse shot proceeded, which is accompanied by the decrease in microwave power. By comparing the experimental results of two cathode materials (carbon fiber and stainless steel), it was found that the above behavior is independent of the cathode materials. The ion flow, induced by the repetitive action of beam electrons with the anode grid, directly affects the development of beam current. A twice-increased process of ion flow was observed, and there are two factors involved in this process, namely, the reflection of electrons between the cathode and virtual cathode and the effect of one-time bombardment of electron beam. After the irradiation of pulsed electron beam, some microprotrusions toward the cathode appeared on the anode surface, with a quasiperiodic structure. The appearance of ion flow, as the anode plasma forms, increases the beam current and enhances the beam current density. The anode plasma is generated relatively easily as the shot test proceeds, due to the aging of anode grid, which allows the possibility of the decrease in the microwave power. As the pulse shot proceeds, the changes in the rise rate of beam current are closely related to the aging process of anode surface. Therefore, the further enhancement of vircator efficiency needs to lengthen the lifetime of anode, besides the optimization of explosive emission cathodes.

  7. Real-Time Control, Acquisition and Data Treatment for Beam Current Transformers in a Transfer Line

    CERN Document Server

    Carter, C; Gelato, G; Lenardon, F; Ludwig, M; Schnell, J D

    1997-01-01

    Particle beams are transferred from the 1 GeV Booster to the 26 GeV Proton Synchrotron and to an experimental area, ISOLDE. The characteristics of the beams and their destination change on a 1.2 s cycle basis. There are six beam current transformers to measure the beam intensities, i.e. the number of particles passing through the transfer lines. On each pulse of the Booster, a real-time system, called BTTR (Beam Transfer TRansformers), acquires the transformer values, selects the range, executes a calibration, and treats the data. Part of the treatment is the subtraction of the base-value, which includes systematic perturbations, acquired in the absence of beam. The system also handles asynchronous tasks, such as acquisition of base-value, readout of calibration factors and other diagnostic actions. The concept of the BTTR and its design are presented, as well as some practical results.

  8. Instrument for spatially resolved simultaneous measurements of forces and currents in particle beams

    Science.gov (United States)

    Spethmann, A.; Trottenberg, T.; Kersten, H.

    2015-01-01

    The article presents a device for spatially resolved and simultaneous measurements of forces and currents in particle beams, especially in beams composed of ions and neutral atoms. The forces are exerted by the impinging beam particles on a plane circular conductive target plate of 20 mm diameter mounted on a pendulum with electromagnetic force compensation. The force measurement in the micronewton range is achieved by electromagnetic compensation by means of static Helmholtz coils and permanent magnets attached to the pendulum. Exemplary measurements are performed in the 1.2 keV beam of a broad beam ion source. The simultaneous measurements of forces and currents onto the same target are compared with each other and with Faraday cup measurements.

  9. Instrument for spatially resolved simultaneous measurements of forces and currents in particle beams

    Energy Technology Data Exchange (ETDEWEB)

    Spethmann, A., E-mail: spethmann@physik.uni-kiel.de; Trottenberg, T., E-mail: trottenberg@physik.uni-kiel.de; Kersten, H., E-mail: kersten@physik.uni-kiel.de [Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, D-24098 Kiel (Germany)

    2015-01-15

    The article presents a device for spatially resolved and simultaneous measurements of forces and currents in particle beams, especially in beams composed of ions and neutral atoms. The forces are exerted by the impinging beam particles on a plane circular conductive target plate of 20 mm diameter mounted on a pendulum with electromagnetic force compensation. The force measurement in the micronewton range is achieved by electromagnetic compensation by means of static Helmholtz coils and permanent magnets attached to the pendulum. Exemplary measurements are performed in the 1.2 keV beam of a broad beam ion source. The simultaneous measurements of forces and currents onto the same target are compared with each other and with Faraday cup measurements.

  10. Characterization of Charging Control of a Single Wafer High Current Spot Beam Implanter

    International Nuclear Information System (INIS)

    This paper focuses on the characterization of charging control of an Axcelis Optima HD single wafer high current spot beam implanter using MOS capacitors with attached antennas of different size and shape. Resist patterns are implemented on Infineon Technologies own charging control wafers to investigate the influence of photo resist on charging damage. Compared to batch high current implanters the design of the beamline and the beam shape are comparable to single wafer high current spot beam implanters, however due to the different scanning architecture the dose rate of the single wafer high current spot beam implanters is significantly higher compared to the batch tools. Therefore, the risk of charging damage will be higher. The charging damage was studied as a function of the energy, the beam current and the most important plasma flood gun parameters. The results have shown that for very high antenna ratios the charging damage for single wafer implanters, even spot or ribbon beam implanters, is higher than for high current batch implanters.

  11. High current relativistic beam propagates stably in gas surrounded by nonconducting walls

    International Nuclear Information System (INIS)

    LLL has been studying the propagation of high current electron beams for a number of years to understand their behavior for use in a variety of experimental uses. Our latest experiments have shown that a mildly relativistic electron beam of 10 to 15 kA and a pulse width of 30 to 40 ns can propagate stably and with no net current transfer in insulating tubes filled with neutral gases. These experiments have been performed in the Magnetic Fusion Energy program where Electronics Engineering has been operating an electron beam accelerator, designing some of the diagnostics, such as laser interferometers, and performing the experiments. This article briefly describes our experimental observations

  12. DEVELOPMENT OF ACCELERATOR DATA REPORTING SYSTEM AND ITS APPLICATION TO TREND ANALYSIS OF BEAM CURRENT DATA

    Energy Technology Data Exchange (ETDEWEB)

    Padilla, M.J.; Blokland, W.

    2009-01-01

    Detailed ongoing information about the ion beam quality is crucial to the successful operation of the Spallation Neutron Source at Oak Ridge National Laboratory. In order to provide the highest possible neutron production time, ion beam quality is monitored to isolate possible problems or performance-related issues throughout the accelerator and accumulator ring. For example, beam current monitor (BCM) data is used to determine the quality of the beam transport through the accelerator. In this study, a reporting system infrastructure was implemented and used to generate a trend analysis report of the BCM data. The BCM data was analyzed to facilitate the identifi cation of monitor calibration issues, beam trends, beam abnormalities, beam deviations and overall beam quality. A comparison between transformed BCM report data and accelerator log entries shows promising results which represent correlations between the data and changes made within the accelerator. The BCM analysis report is one of many reports within a system that assist in providing overall beam quality information to facilitate successful beam operation. In future reports, additional data manipulation functions and analysis can be implemented and applied. Built-in and user-defi ned analytic functions are available throughout the reporting system and can be reused with new data.

  13. Production of a high-current microsecond electron beam with a large cross section

    International Nuclear Information System (INIS)

    Obtaining high-current wide-aperture electron beams is an important problem in the development of laser technology for controlled nuclear fusion and for solving ecological and technological problems. The main scheme for producing such beams involves the use of generators with intermediate energy storage devices and burst-emission vacuum diodes. Beam pinching is prevented by using an external magnetic field or sectioning the diode into magnetically insulated diodes with currents lower than the limiting current. The length of the electron-current pulse varies from tens to hundreds of nano-seconds and is limited by the parameters of the intermediate storage device. Here the authors study the formation of a high-current electron beam with a square cross section and a current of the order of the limiting current of the diode in the absence of an external magnetic field as well as a 'fast' storage device in the power supply circuit. These conditions as a whole correspond to a simpler electron-source circuit, but the beam forming becomes more complicated. The reason for this is that there is no external magnetic field and that the role of plasma processes in the diode is enhanced by the greater length of the electron-current pulses

  14. Wideband Precision Current Transformer for the Magnet Current of the Beam Extraction Kicker Magnet of the Large Hadron Collider

    CERN Document Server

    Gräwer, G

    2004-01-01

    The LHC beam extraction system is composed of 15 fast kicker magnets per beam to extract the particles in one turn of the collider and to safely dispose them on external absorbers. Each magnet is powered by a separate pulse generator. The generator produces a magnet current pulse with 3 us rise time, 20 kA amplitude and 1.8 ms fall time, of which 90 us are needed to dump the beam. The beam extraction system requires a high level of reliability. To detect any change in the magnet current characteristics, which might indicate a slow degradation of the pulse generator, a high precision wideband current transformer will be installed. For redundancy reasons, the results obtained with this device will be cross-checked with a Rogowski coil, installed adjacent to the transformer. A prototype transformer has been successfully tested at nominal current levels and showed satisfactory results compared with the output of a high frequency resistive coaxial shunt. The annular core of the ring type transformer is composed of...

  15. Exploring the energy/beam current parameter space for the isotope production facility (IPF) at LANSCE

    Energy Technology Data Exchange (ETDEWEB)

    Gulley, Mark S [Los Alamos National Laboratory; Bach, Hong [Los Alamos National Laboratory; Nortier, Francis M [Los Alamos National Laboratory; Pillai, Chandra [Los Alamos National Laboratory; Bitteker, Leo J [Los Alamos National Laboratory; John, Kevin D [Los Alamos National Laboratory; Valdez, Frank O [Los Alamos National Laboratory; Seifter, Achim [Los Alamos National Laboratory

    2010-09-07

    IPF has recently investigated isotope production with proton beams at energies other than the 100-MeV currently available to the IPF beam line. To maximize the yield of a particular isotope, it is necessary to measure the production rate and cross section versus proton beam energy. Studies were conducted at 800 MeV and 197 MeV to determine the cross section of Tb-159. Also, the ability to irradiate targets at different proton beam energies opens up the possibility of producing other radioisotopes. A proof-of-principle test was conducted to develop a 40-MeV tune in the 100-MeV beam line. Another parameter explored was the beam current, which was raised from the normal limit of 250 {mu}A up to 356 {mu}A via both power and repetition rate increase. This proof-of-principle test demonstrated the capability of the IPF beam line for high current operation with potential for higher isotope yields. For the full production mode, system upgrades will need to be in place to operate at high current and high duty factor. These activities are expected to provide the data needed for the development of a new and unique isotope production capability complementing the existing 100-MeV IPF facility.

  16. Low-impedance plasma systems for generation of high-current low-energy electron beams

    Science.gov (United States)

    Agafonov, A. V.

    2006-12-01

    The results of experimental investigation and numerical modeling of the generation of low-energy (tens of keV) high-current (up to tens of kA) electron beams in a low-impedance system consisting of a plasma-filled diode with a long plasma anode, an auxiliary hot cathode, and an explosive emission cathode. The low-current low-voltage beam from the auxiliary cathode in an external longitudinal magnetic field is used to produce a long plasma anode, which is simultaneously the channel of beam transportation by residual gas ionization. The high-current electron beam is formed from the explosive emission cathode placed in the preliminarily formed plasma. Numerical modeling is performed using the KARAT PIC code.

  17. High beam current shut-off systems in the APS linac and low energy transfer line

    International Nuclear Information System (INIS)

    Two independent high beam current shut-off current monitoring systems (BESOCM) have been installed in the APS linac and the low energy transport line to provide personnel safety protection in the event of acceleration of excessive beam currents. Beam current is monitored by a fast current transformer (FCT) and fully redundant supervisory circuits connected to the Access Control Interlock System (ACIS) for beam intensity related shutdowns of the linac. One FCT is located at the end of the positron linac and the other in the low energy transport line, which directs beam to the positron accumulator ring (PAR). To ensure a high degree of reliability, both systems employ a continuous self-checking function, which injects a test pulse to a single-turn test winding after each ''real'' beam pulse to verify that the system is fully functional. The system is designed to be fail-safe for all possible system faults, such as loss of power, open or shorted signal or test cables, loss of external trigger, malfunction of gated integrator, etc. The system has been successfully commissioned and is now a reliable part of the total ACIS

  18. Impact of Electric Current Fluctuations Arising from Power Supplies on Charged-Particle Beams

    CERN Document Server

    Yoon, P S

    2008-01-01

    Electric current fluctuations are one type of unavoidable machine imperfections,and induce magnetic-field perturbations as a source of instabilities in accelerators. This paper presents measurement-based methodology of modeling the fluctuating electric current arising from the power system of Fermilab's Booster synchrotron to discuss the ramifications of the presence of ripple current and space-charge defocusing effects. We also present the method of generating stochastic noise and the measurement and analysis methods of ripple current and offending electromagnetic interferences residing in the Booster power system. This stochastic noise model, accompanied by a suite of beam diagnostic calculations, manifests that the fluctuating power-supply current, when coupled to space charge and impinging upon a beam, can substantially enhance beam degradation phenomena--such as emittance growth and halo formation--during the Booster injection period. With idealized and uniform charge-density distribution, fractional gro...

  19. High Current Beam Dynamics in an Ess SC Linac

    CERN Document Server

    Pabst, M; Letchford, A P

    2000-01-01

    Three alternative designs of the European Spallation Source (ESS) high energy linac are described. The most promising ones are either a normalconducting (nc) coupled cavity linac (CCL) up tofinal energy or a change at 407 MeV to only one group of 6 cell superconducting (sc) elliptical cavities. Fully 3d Monte Carlo simulations are presented for both options, optimized for reduced halo formation at the linac end. For the error free matched case, especially the halo formation in the longitudinal plane is more pronounced for the hybrid solution with its superconducting cavities, caused by the unavoidable phase slippage, but still quite well acceptable for loss free ring injection. Simulations however for a 30% mismatched dense core, surrounded in addition by 1.5% halo particles are showing few particles with very large amplitudes even in real space. This case represents halo formation in front to end simulations, caused by current fluctuations, filamented RFQ output distribution and enhanced by accumulated field...

  20. Design and commissioning of the APS beam charge and current monitor

    International Nuclear Information System (INIS)

    The non-intercepting charge and current monitors suitable for a wide range of beam parameters have been developed and installed in the Advanced Photon Source (APS) low energy transport lines, positron accumulator ring (PAR), and injector synchrotron. The positron or electron beam pulse in the APS has charge ranging from 100pC to l0nC with pulse width varying from 30ps to 30ns. The beam charge and current are measured with a current transformer and subsequent current monitoring electronics based on an ultrafast, high precision gated integrator. The signal processing electronics, data acquisition, and communication with the control system are managed by a VME-based system. This paper summarizes the hardware and software features of the systems. The results of recent operations are presented

  1. Applicability evaluation of eddy current testing for underwater laser beam welding

    International Nuclear Information System (INIS)

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

  2. Results of Beam Tests on a High Current EBIS Test Stand

    International Nuclear Information System (INIS)

    At Brookhaven National Laboratory there is an R and D program to design an Electron Beam Ion Source (EBIS) for use in a compact ion injector to be developed for the relativistic heavy ion collider (RHIC). The BNL effort is directed at developing an EBIS with intensities of 3 x 109 particles/pulse of ions such as Au35+ and U45+, and requires an electron beam on the order of 10A. The construction of a test stand (EBTS) with the full electron beam power and 1/3 the length of the EBIS for RHIC is nearing completion. Initial commissioning of the EBTS was made with pulsed electron beams of duration < 1 ms and current up to 13 A. Details of the EBTS construction, results of the pulse tests, and preparations for DC electron beam tests are presented

  3. HIGH AVERAGE CURRENT LOW EMITTANCE BEAM EMPLOYING CW NORMAL CONDUCTING GUN.

    Energy Technology Data Exchange (ETDEWEB)

    CHANG,X.; BEN-ZVI, I.; KEWISCH, J.; PAI, C.

    2007-06-25

    CW normal conducting guns usually do not achieve very high field gradient and waste much RF power at high field gradient compared to superconducting cavities. But they have less trapped modes and wakefields compared to the superconducting cavities due to their low Q. The external bucking coil can also be applied very close to the cathode to improve the beam quality. By using a low frequency gun with a recessed cathode and a carefully designed beam line we can get a high average current and a high quality beam with acceptable RF power loss on the cavity wall. This paper shows that the CW normal conducting gun can be a backup solution for those projects which need high peak and average current, low emittance electron beams such as the Relativistic Heavy Ion Collider (RHIC) e-cooling project and Energy Recovery Linac (Em) project.

  4. Analysis of Longitudinal Beam Dynamics Behavior and RF System Operative Limits at High Beam Currents in Storage Rings

    Energy Technology Data Exchange (ETDEWEB)

    Mastorides, T; Rivetta, C.; Fox, J.D.; Winkle, D.Van; /SLAC; Tytelman, D.; /Dimtel, Redwood City

    2008-07-07

    A dynamics simulation model is used to estimate limits of performance of the Positron-Electron Project (PEP-II). The simulation captures the dynamics and technical limitations of the Low Level Radio Frequency (LLRF) system, the high-power RF components and the low-order mode coupled bunch longitudinal beam dynamics. Simulation results showing the effect of non-linearities on the LLRF loops, and studies of the effectiveness of technical component upgrades are reported, as well as a comparison of these results with PEP-II measurements. These studies have led to the estimation of limits and determining factors in the maximum stored current that the Low Energy Ring/High Energy Ring (LER/HER) can achieve, based on system stability for different RF station configurations and upgrades. In particular, the feasibility of the PEP-II plans to achieve the final goal in luminosity, which required an increase of the beam currents to 4A for LER and 2.2A for HER, is studied. These currents are challenging in part because they would push the longitudinal low-order beam mode stability to the limit, and the klystron forward power past a level of satisfactory margin. An acceptable margin is defined in this paper, which in turn determines the corresponding klystron forward power limitation.

  5. Focusing of heavy ion beams by a high-current plasma lens

    International Nuclear Information System (INIS)

    Results are presented from studies of the focusing of wide-aperture low-energy (100-400 eV) and moderate-energy (5-25 keV) beams of heavy-metal ions by a high-current electrostatic plasma lens. It is found experimentally that, because of the significant electron losses, the efficient focusing of such beams can be achieved only if the external potentials at the plasma-lens electrodes are maintained constant. Static and dynamic characteristics of the lens are studied under these conditions. It is shown that, as the beam current and the electrode voltage increase, the maximum electrostatic field in the lens tends to a certain limiting value because of the increase in the spatial potential near the lens axis. The role of spherical and moment aberrations in the focusing of wide-aperture low-divergence ion beams is revealed. It is shown that, even when spherical aberrations are minimized, unremovable moment aberrations decrease the maximum compression ratio of a low-energy heavy-ion beam because of the charge separation of multiply charged ions in the focal region. At the same time, as the ion energy increases, the role of the moment aberrations decreases and the focusing of high-current heavy-ion beams by a plasma lens becomes more efficient than the focusing of light-ion (hydrogen) beams. This opens up the possibility of using electrostatic plasma lenses to control ion beams in high-dose ion implanters and high-current accelerators of heavy ions

  6. Stable propagation of a high-current electron beam: experimental observations and computational modeling

    International Nuclear Information System (INIS)

    Experimental studies of self-focused, high-current electron-beam propagation phenomena are compared with the results of computational modeling. The model includes the radial structure of the beam-plasma system, a full electromagnetic field description, primary and secondary gas ionization processes, and a linear theory of the hose-like distortions. Good agreement between the experimental results and the computations strengthens the premise that hose instability is the principal limitation to propagation at high pressure

  7. Current status of electron beam treatment of flue gas in China

    International Nuclear Information System (INIS)

    Fossil resource especially coal will remain the main energy resource in China over the next 3 ∼4 decades. Pollution of flue gas from fossil power station is one problem being desiderated to solve since 1990's. Electron beam treatment of flue gas as an advanced technique has been developed and used by some institutes and industries in China. The current status of flue gas treatment using electron beam and the development of electron accelerator in China are reviewed. (author)

  8. Measurements of current density distribution in shaped e-beam writers

    Czech Academy of Sciences Publication Activity Database

    Bok, Jan; Horáček, Miroslav; Kolařík, Vladimír; Urbánek, Michal; Matějka, Milan; Krzyžánek, Vladislav

    2016-01-01

    Roč. 149, JAN 5 (2016), s. 117-124. ISSN 0167-9317 R&D Projects: GA ČR(CZ) GA14-20012S; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : shaped e-beam writer * electron beam * current density Subject RIV: JB - Sensors, Measurment, Regulation Impact factor: 1.197, year: 2014

  9. Focusing of heavy ion beams by a high-current plasma lens

    International Nuclear Information System (INIS)

    The results of studies on focusing the wide-aperture heavy ion beams by a high-current electrostatic plasma lens within the range of low (100-400 eV) and medium (5-25 keV) energies are presented. It si established, that due to significant electron leakages the effective focusing of such beams is possible only under the condition of rigid fixation of the external potentials on the plasma lens electrodes. The peculiarities of the lens static and dynamic characteristics under such conditions are studied. The role of spherical and moment aberrations by focusing the wide-aperture weakly-diverging ion beams is identified. It is shown, that the role of the moment aberrations decreases with the energy growth, and focusing of the heavy elements high-current beams by the plasma lens becomes considerably more efficient as compared, to the focusing of the hydrogen light ion beams. This opens the possibility for application of electrostatic plasma lenses for controlling the ion beams in the high-dose ion implanters and in the high-current heavy-ion accelerators

  10. High-current pulse sources of broad beams of gas and metal ions for surface treatment

    International Nuclear Information System (INIS)

    This paper reviews the experimental study, development, and improvement of various types of processing ion sources undertaken in association with the joint program performed in recent years by the Institute of Electrophysics and the Institute of High-Current Electronics of the Russian Academy of Sciences. The beam parameters (type and energy of ions, current density, cross-sectional area of the beam, permissible content of impurities, etc.) should meet the requirements of particular ion beam treatment conditions, while the ion source itself should be simple and reliable in operation. Technical and service characteristics of the developed ion sources permit their use for ion-beam modification of materials, preparation of surfaces and ion-assisted deposition of thin films, and in some other applications. The sources under consideration employ high-current glow discharges with a hollow cathode or in crossed electric and magnetic fields, and low-pressure arc discharges and vacuum arc. Cold cathodes enhance reliability of the ion sources when they work at a high residual gas pressure or in the reactive gas media. The repetitive pulse mode of the plasma and beam generation provides optimum conditions for stable operation of the discharge, control of the average beam current over a wide range, and formation of homogeneous large-cross-section beams. The paper describes techniques used to realize high-current discharges at a reduced pressure, methods for producing a stable, dense and homogeneous plasma in a large volume, techniques of formation of large-cross-section homogeneous beams, and also findings on the mass-charge composition of the plasma and beams produced. Some design versions of the sources are given. At voltages from 10 to 100 kV, the pulse duration of 10 to 1000 μs, and the pulse repetition rate of 1 to 500 Hz these sources provide the current density of ∼1-10 mA/cm2 in beams having the cross-sectional area of a few hundreds of square centimeters. The

  11. Application of intense relativistic electron beams to the switching of high currents in high power electrical networks

    International Nuclear Information System (INIS)

    A new concept of switching of high currents using intense relativistic electron beams propagating in vacuum drift tubes is presented. Some possible applications of this concept for the design of current switches are discussed. Supporting analytical one-dimensional theory of an electron beam switch is given. Electron beam hysteresis phenomenon associated with the switching mechanism is briefly discussed

  12. Modeling of explosive electron emission and electron beam dynamics in high-current devices

    International Nuclear Information System (INIS)

    Based on a detailed analysis of explosive electron emission in high-current electronic devices, we formulate a system of equations that describes the expansion of the cathode plasma and the generation of high-current electron beams. The system underlies the numerical algorithm for the hybrid code which enables simulating the charged particles' dynamics in high-current vircators with open resonators. Using the Gabor-Morlet transform, we perform the time-frequency analysis of vircator radiation

  13. Modeling of explosive electron emission and electron beam dynamics in high-current devices

    Science.gov (United States)

    Anishchenko, S. V.; Gurinovich, A. A.

    2014-03-01

    Based on a detailed analysis of explosive electron emission in high-current electronic devices, we formulate a system of equations that describes the expansion of the cathode plasma and the generation of high-current electron beams. The system underlies the numerical algorithm for the hybrid code which enables simulating the charged particles' dynamics in high-current vircators with open resonators. Using the Gabor-Morlet transform, we perform the time-frequency analysis of vircator radiation.

  14. Current-voltage relation for a field ionizing He beam detector

    International Nuclear Information System (INIS)

    Emerging interest in utilizing the transverse coherence properties of thermal energy atomic and molecular beams motivates the development of ionization detectors with near unit detection efficiency and adequate spatial resolution to resolve interference fringes of submicron dimension. We demonstrate that a field ionization tip coupled to a charged particle detector meets these requirements. We have systematically studied the current-voltage relationship for field ionization of helium using tungsten tips in diffuse gas and in a supersonic helium beam. For all 16 tips used in this study, the dependence of ion current on voltage for tips of fixed radius was found to differ from that for tips held at constant surface electric field. A scaling analysis is presented to explain this difference. Ion current increased on average to the 2.8 power of voltage for a tip at fixed field and approximately fifth power of voltage for fixed radius for a liquid nitrogen cooled tip in room temperature helium gas. For the helium beam, ion current increased as 2.2 power of voltage with constant surface field. The capture region of the tips was found to be up to 0.1 μm2 for diffuse gas and 0.02 μm2 in the beam. Velocity dependence and orientation of tip to beam were also studied

  15. Neutral beam heating and current drive system and its role in ITER-FEAT operation scenarios

    International Nuclear Information System (INIS)

    The NB H and CD system, providing 33 MW in deuterium beams at 1 MeV from two injectors, in addition to 40 MW RF power, contributes to heating a plasma to sub-ignition through the L-H mode transition followed by finite-Q driven-burn (Q≥10), and achievement of a hybrid operation with an extended-duration (∼1000 s) or steady-state operation with Q≤5. To achieve such operations, the NB provides non-inductive current drive by injecting the beams tangentially into the plasma with the capability of on- and off-axis current drive. The present engineering design is under the constraints of the beam envelope, vacuum confinement, neutron shielding, tolerances, and clearances required with the toroidal field coils. The on- and off-axis current drive is to be achieved by tilting the beam axis vertically. Each beam axis of the NB injectors can be tilted independently, providing flexibility in the control of heating and the driven current profile. (author)

  16. A Fast Non Intercepting Linac Electron Beam Position and Current Monitor

    DEFF Research Database (Denmark)

    Hansen, Jørgen-Walther; Wille, Mads

    A non-intercepting beam monitor consisting of four detecting loops is used to determine the spatial postion and current of a pulsed beam from an electron linear accelerator. The monitor detects the magnetic field radiated by the substructure of the electron bunches created by the accelerating...... microwave. The detecting loops are interconnected two by two, by means of two coaxial hybrid junctions, the two sets positioned perpendicular to each other. By means of the two signals from the diametrically positioned detecting loops, a good spatial displacement and current monitoring sensitivity are...

  17. Radiation damage in single crystal CVD diamond material investigated with a high current Au beam

    International Nuclear Information System (INIS)

    Single-crystal Chemical Vapor Deposition (ScCVD) diamond based prototype detectors have been constructed for the high current heavy ion experiments HADES and CBM at the future FAIR facility at GSI Darmstadt. Their properties have been studied with a high current density beam (about 2-3 x 106/s/mm2) of 1.25 A GeV Au ions. Details of the design, the intrinsic properties of the detectors and their performance after irradiation with such beam are reported.

  18. Effects of a dielectric material in an ion source on the ion beam current density and ion beam energy

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, Y., E-mail: yutaka-fujiwara@aist.go.jp; Sakakita, H.; Nakamiya, A. [Department of Engineering Mechanics and Energy, University of Tsukuba, Ibaraki 305-8577 (Japan); Innovative Plasma Processing Group, National Institute of Advanced Industrial Science and Technology (AIST), Ibaraki 305-8568 (Japan); Hirano, Y.; Kiyama, S. [Innovative Plasma Processing Group, National Institute of Advanced Industrial Science and Technology (AIST), Ibaraki 305-8568 (Japan)

    2016-02-15

    To understand a strong focusing phenomenon that occurs in a low-energy hydrogen ion beam, the electron temperature, the electron density, and the space potential in an ion source with cusped magnetic fields are measured before and after the transition to the focusing state using an electrostatic probe. The experimental results show that no significant changes are observed before or after the transition. However, we found unique phenomena that are characterized by the position of the electrostatic probe in the ion source chamber. Specifically, the extracted ion beam current density and energy are obviously enhanced in the case where the electrostatic probe, which is covered by a dielectric material, is placed close to an acceleration electrode.

  19. A Four Channel Beam Current Monitor Data Acquisition System Using Embedded Processors

    Energy Technology Data Exchange (ETDEWEB)

    Wheat, Jr., Robert Mitchell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dalmas, Dale A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dale, Gregory E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-08-11

    Data acquisition from multiple beam current monitors is required for electron accelerator production of Mo-99. A two channel system capable of recording data from two beam current monitors has been developed, is currently in use, and is discussed below. The development of a cost-effective method of extending this system to more than two channels and integrating of these measurements into an accelerator control system is the main focus of this report. Data from these current monitors is digitized, processed, and stored by a digital data acquisition system. Limitations and drawbacks with the currently deployed digital data acquisition system have been identified as have been potential solutions, or at least improvements, to these problems. This report will discuss and document the efforts we've made in improving the flexibility and lowering the cost of the data acquisition system while maintaining the minimum requirements.

  20. Microcontroller based four-channel current readout unit for beam slit monitor

    International Nuclear Information System (INIS)

    This paper describes the design and development of a microcontroller based four-channel current readout unit for Beam Slit Monitor (BSM) installed in Transport Line-1 of Indus Accelerator Complex. BSM is a diagnostic device consisting of two horizontal and two vertical blades, which can be moved independently in to the beam pipe to cut the beam transversely. The readout unit employs switched integrators with reset, hold and select switches and timing and control unit. It integrates the current output of the four blades of BSM and produces an output corresponding to the beam charge intercepted by the blade. The integrator outputs are then multiplexed and digitized using 12-bit ADC. Acquired digital data from ADC is stored into on-chip RAM of the microcontroller. The readout sequence is synchronized with the Microtron beam-timing signal. The timing of integration, hold and reset cycles is controlled by the microcontroller. The unit is connected on a serial link to the host computer in main control room. This unit has been integrated with the BSM system and is being used to obtain the electron beam profile. (author)

  1. Modulation of auroral electrojet currents using dual HF beams with ELF phase offset

    Science.gov (United States)

    Golkowski, M.; Cohen, M.; Moore, R. C.

    2012-12-01

    The modulation of naturally occuring ionospheric currents with high power radio waves in the high frequency (HF, 3-10 MHz) band is a well known technique for generation of extremely low frequency (ELF, 3-3000 Hz) and very low frequency (VLF, 3-30 kHz) waves. We use the heating facility of the High Frequency Active Auroral Research Program (HAARP) to investigate the effect of using dual HF beams with an ELF/VLF phase offset between the modulation waveforms. Experiments with offset HF beams confirm the model of independent ELF/VLF sources. Experiments with co-located HF beams exhibit interaction between the first and second harmonics of the modulated tones when square and sine wave modulation waveforms are employed. Using ELF/VLF phase offsets for co-loacted beams is also shown to be a potential diagnostic for the D-region ionospheric profile.

  2. A Particle In Cell code development for high current ion beam transport and plasma simulations

    CERN Document Server

    Joshi, N

    2016-01-01

    A simulation package employing a Particle in Cell (PIC) method is developed to study the high current beam transport and the dynamics of plasmas. This package includes subroutines those are suited for various planned projects at University of Frankfurt. In the framework of the storage ring project (F8SR) the code was written to describe the beam optics in toroidal magnetic fields. It is used to design an injection system for a ring with closed magnetic field lines. The generalized numerical model, in Cartesian coordinates is used to describe the intense ion beam transport through the chopper system in the low energy beam section of the FRANZ project. Especially for the chopper system, the Poisson equation is implemented with irregular geometries. The Particle In Cell model is further upgraded with a Monte Carlo Collision subroutine for simulation of plasma in the volume type ion source.

  3. Supershort electron beam and voluminous heavy-current air discharge at atmospheric pressure

    International Nuclear Information System (INIS)

    The conditions of the electron beam and voluminous discharge formation in the air at the atmospheric pressure and subnanosecond pulse tension front are studied. It is shown that the electron beam in the gaseous diode originates at the pulse tension front over time of ∼ 0.5 ns and has duration at the semiheight of ≤0.4 ns. The electron beam with the electrons average energy of 60-80 keV and current amplitude of ≥70 A is obtained. It is assumed that the electron beam is formed from the electron avalanches, originating in the gap on the account of the gas ionization by fast electrons at achieving the critical field between the expanding plasma cloud front and anode

  4. Recent Improvements to the Control of the CTF3 High-Current Drive Beam

    CERN Document Server

    Constance, B; Gamba, D; Skowronski, P K

    2013-01-01

    In order to demonstrate the feasibility of the CLIC multiTeV linear collider option, the drive beam complex at the CLIC Test Facility (CTF3) at CERN is providing highcurrent electron pulses for a number of related experiments. By means of a system of electron pulse compression and bunch frequency multiplication, a fully loaded, 120 MeV linac is used to generate 140 ns electron pulses of around 28 Amperes. Subsequent deceleration of this high-current drive beam demonstrates principles behind the CLIC acceleration scheme, and produces 12 GHz RF power for experimental purposes. As the facility has progressed toward routine operation, a number of studies aimed at improving the drive beam performance have been carried out. Additional feedbacks, automated steering programs, and improved control of optics and dispersion have contributed to a more stable, reproducible drive beam with consequent benefits for the experiments.

  5. Current status and future prospect of electron beam sterilization in Japan

    Science.gov (United States)

    Katsura, Ichiro

    1998-06-01

    It seems that electron beam sterilization is being current topic among all applications in Japan and that this tendency will continue until when major companies interested in the technology complete introducing electron beam. Since the Ministry of Health and Welfare(MOHW) officially issued revised regulation on GMP for medical devices in 1995, EtO has become the method regarded as time and money consuming one. On the contrary, electron beam has become as relatively economical and desirable method to achieve same result by its characteristics such as high productivity, rather easy validation and consequent cost reduction, although less penetration limit the kind of products to be treated. Status and prospect of electron beam sterilization in Japan will be presented in the paper along with accelerator related technologies.

  6. Aberrations due to solenoid focusing of a multiply charged high-current ion beam

    CERN Document Server

    Grégoire, G; Lisi, N; Schnuriger, J C; Scrivens, R; Tambini, J

    2000-01-01

    At the output of a laser ion source, a high current of highly charged ions with a large range of charge states is available. The focusing of such a beam by magnetic elements causes a nonlinear space-charge field to develop which can induce large aberrations and emittance growth in the beam. Simulation of the beam from the CERN laser ion source will be presented for an ideal magnetic and electrostatic system using a radially symmetric model. In addition, the three dimensional software KOBRA3 is used for the simulation of the solenoid line. The results of these simulations will be compared with experiments performed on the CERN laser ion source with solenoids (resulting in a hollow beam) and a series of gridded electrostatic lenses. (5 refs).

  7. A detector based on silica fibers for ion beam monitoring in a wide current range

    Science.gov (United States)

    Auger, M.; Braccini, S.; Carzaniga, T. S.; Ereditato, A.; Nesteruk, K. P.; Scampoli, P.

    2016-03-01

    A detector based on doped silica and optical fibers was developed to monitor the profile of particle accelerator beams of intensity ranging from 1 pA to tens of μA. Scintillation light produced in a fiber moving across the beam is measured, giving information on its position, shape and intensity. The detector was tested with a continuous proton beam at the 18 MeV Bern medical cyclotron used for radioisotope production and multi-disciplinary research. For currents from 1 pA to 20 μA, Ce3+ and Sb3+ doped silica fibers were used as sensors. Read-out systems based on photodiodes, photomultipliers and solid state photomultipliers were employed. Profiles down to the pA range were measured with this method for the first time. For currents ranging from 1 pA to 3 μA, the integral of the profile was found to be linear with respect to the beam current, which can be measured by this detector with an accuracy of ~1%. The profile was determined with a spatial resolution of 0.25 mm. For currents ranging from 5 μA to 20 μA, thermal effects affect light yield and transmission, causing distortions of the profile and limitations in monitoring capabilities. For currents higher than ~1 μA, non-doped optical fibers for both producing and transporting scintillation light were also successfully employed.

  8. Non-linear pressure rise with beam current in BEPC II positron ring

    International Nuclear Information System (INIS)

    It was found that the pressure-current curves were linear in electron ring, while non-linear in positron ring, especially in arc sections of positron ring. It might be since that the synchrotron photoelectrons transversely kicked by the positron beam bunches hit the vacuum chamber surface and the hit produces secondary electrons, which cause beam-induced multipacting (BIM) and large outgassing under some conditions. To find these conditions, bunch filling patterns of positron beams were changed to derive the corresponding non-linear pressure-current curves. The result is consistent with that from KEK-B low energy ring, which shows the non-linearity exhibits a threshold behavior. The non-linearity will take place only when the single bunch current and the quantity of the successive bunch in one train are both sufficiently large. With the total current increasing, BEPC II positron beam should take certain bunch filling patterns of smaller single bunch current and larger bunch number to avoid BIM. (authors)

  9. Glucagon-like peptide-1 enhances cardiac L-type Ca2+ currents via activation of the cAMP-dependent protein kinase A pathway

    Directory of Open Access Journals (Sweden)

    Jaye Deborah A

    2011-01-01

    Full Text Available Abstract Background Glucagon-like peptide-1 (GLP-1 is a hormone predominately synthesized and secreted by intestinal L-cells. GLP-1 modulates multiple cellular functions and its receptor agonists are now used clinically for diabetic treatment. Interestingly, preclinical and clinical evidence suggests that GLP-1 agonists produce beneficial effects on dysfunctional hearts via acting on myocardial GLP-1 receptors. As the effects of GLP-1 on myocyte electrophysiology are largely unknown, this study was to assess if GLP-1 could affect the cardiac voltage-gated L-type Ca2+ current (ICa. Methods The whole-cell patch clamp method was used to record ICa and action potentials in enzymatically isolated cardiomyocytes from adult canine left ventricles. Results Extracellular perfusion of GLP-1 (7-36 amide at 5 nM increased ICa by 23 ± 8% (p Ca; however, the increase in ICa was abolished if Exendin (9-39 was pre-applied 5 min prior to GLP-1 administration. Intracellular dialysis with a protein kinase A inhibitor also blocked the GLP-1-enhanced ICa. In addition, GLP-1 at 5 nM prolonged the durations of the action potentials by 128 ± 36 ms (p p Conclusions Our data demonstrate that GLP-1 enhances ICa in canine cardiomyocytes. The enhancement of ICa is likely via the cAMP-dependent protein kinase A mechanism and may contribute, at least partially, to the prolongation of the action potential duration.

  10. Magnetic focusing of cold atomic beam with a 2D array of current-carrying wires

    Institute of Scientific and Technical Information of China (English)

    Yang Liu; Min Yun; Jianping Yin

    2006-01-01

    @@ A new scheme to realize a two-dimensional (2D) array of magnetic micro-lenses for a cold atomic beam,formed by an array of square current-carrying wires,is proposed.We calculate the spatial distributions of the magnetic fields from the array of current-carrying wires and the magnetic focusing potential for cold rubidium atoms,and study the dynamic focusing processes of cold atoms passing through the magnetic micro-lens array and its focusing properties by using Monte-Carlo simulations and trajectory tracing method.The result shows that the proposed micro-lens array can be used to focus effectively a cold atomic beam,even to load ultracold atoms or a BEC sample into a 2D optical lattice formed by blue detuned hollow beams.

  11. Use of Superimposed Alternating Currents in Quadrupoles to Measure Beam Position with Respect to their Magnetic Centre

    CERN Document Server

    Marks, N

    2000-01-01

    The positional stability of the electron beam in a modern state-of-the-art synchrotron radiation source is critical, as the many experimental users require consistency in the position and dimensions of the incoming photon beams which are incident on their experimental samples. At the Daresbury Synchrotron Radiation Source (SRS), inaccuracies in the measurements of the positions of both beam position monitors and the lattice quadrupoles can be overcome by measuring the position of the electron beam with respect to the magnetic centres of the quadrupoles. This was achieved by superimposing an alternating ('ripple') current on the direct current excitation of a single lattice quadrupole and examining the resulting beam oscillations at remote positions in the storage ring. If the electron beam is then subjected to a local distortion at the position of this quadrupole, the amplitude of the beam oscillation induced by the superimposed current is minimised (nominally zero) when the beam is at the quadrupole's magnet...

  12. Application of lateral photovoltage towards contactless light beam induced current measurements and its dependence on the finite beam size

    International Nuclear Information System (INIS)

    The nature of the signal due to light beam induced current (LBIC) at the remote contacts is verified as a lateral photovoltage for non-uniformly illuminated planar p-n junction devices; simulation and experimental results are presented. The limitations imposed by the ohmic contacts are successfully overcome by the introduction of capacitively coupled remote contacts, which yield similar results without any significant loss in the estimated material and device parameters. It is observed that the LBIC measurements introduce artefacts such as shift in peak position with increasing laser power. Simulation of LBIC signal as a function of characteristic length Lc of photo-generated carriers and for different beam diameters has resulted in the observed peak shifts, thus attributed to the finite size of the beam. Further, the idea of capacitively coupled contacts has been extended to contactless measurements using pressure contacts with an oxidized aluminium electrodes. This technique avoids the contagious sample processing steps, which may introduce unintentional defects and contaminants into the material and devices under observation. Thus, we present here, the remote contact LBIC as a practically non-destructive tool in the evaluation of device parameters and welcome its use during fabrication steps

  13. Discharge current and current of supershort avalanche E-beam at volume nanosecond discharge in non-uniform electric field

    Science.gov (United States)

    Tarasenko, Victor F.; Rybka, Dmitrii V.; Baksht, Evgenii H.; Kostyrya, Igor'D.; Lomaev, Mikhail I.

    2008-01-01

    The gas diode current-voltage characteristics at the voltage pulses applied from the RADAN and SM-3NS pulsers, and generation of an supershort avalanche electron beam (SAEB) have been studied experimentally in an inhomogeneous electric field upon a nanosecond breakdown in an air gap at atmospheric pressure. Displacement currents with amplitude over 1 kA have been observed and monitored. It is shown that the displacement current amplitude gets increased due to movement of the dense plasma front and charging of a "capacitor" formed between plasma and anode. The SAEB generation time relatively to the discharge current pulses and the gap voltage were determined in the experiments. It is shown that the SAEB current maximum at the pulser voltages of hundreds kV is registered on the discharge current pulse front, before the discharge current peak of the gas diode capacitance, and the delay time of these peaks is determined by the value of an interelectrode spacing. The delay time in case of a gap of 16 mm and air breakdown at atmospheric pressure was ~100 ps, and in case of 10 mm it was less than 50 ps.

  14. Computer simulation of low-energy high-current electron beam dynamics in a long plasma-filled diode

    International Nuclear Information System (INIS)

    Results of computer simulation of low-energy high-current electron beam dynamics in a low-impedance system consisting of a diode with a long plasma anode, just siding with an explosive emission cathode and an auxiliary thermionic cathode are presented. Plasma anode plays simultaneously a role of the transport channel providing charge neutralization of high-current beam and is created by means of the residual gas ionisation by low-current, low-voltage electron beam emitted from the auxiliary cathode in an external longitudinal magnetic field. The main peculiarities of the beam-plasma system are discussed: 1) the formation of the beam of currents exceeding the limiting Alven's ones; 2) the formation of paramagnetic states of the beam under condition of beam charge density close to the plasma density. These peculiarities complicate beam-plasma interaction significantly due to sharp nonuniform distribution of the beam current density, significant transverse motion of the beam electrons and redistribution of ion plasma density under the influence of high-current electron beam fields. Computer simulation was performed using electromagnetic PIC code KARAT

  15. Transverse match of high peak-current beam into the LANSCE DTL using PARMILA

    International Nuclear Information System (INIS)

    A new algorithm that uses a multiparticle PARMILA-based code to match high peak current H+ beam (∼21 mA) into the Los Alamos Neutron Science Center (LANSCE) drift tube linac (DTL) has been developed. Two single cell rf bunchers in the low energy beam transport (LEBT) prepare the initially unbunched beam for DTL capture. The transverse distribution at the entrance to the DTL is set with four quadrupoles in the 1.26 m between the last transverse emittance measuring station and the DTL entrance. Previous matching algorithms used TRACE and TRACE 3-D to determine these quadrupole strengths. PARMILA simulation show this procedure produces non-zero mismatch and additional emittance growth through the DTL for high current beams. Because of strong space-charge forces and a rapidly forming longitudinal bunch, simple envelope calculations do not model the beam evolution in the LEBT well. A PARMILA model of this region was combined with ant iterative search routine to set the LEBT quadrupole strengths to achieve a better transverse match into the DTL. Simulations predict a significant reduction in transverse emittance at the exit of the DTL over the typical TRACE 3-D result

  16. Beam extraction and high stability operation of high current electron cyclotron resonance proton ion source

    Energy Technology Data Exchange (ETDEWEB)

    Roychowdhury, P., E-mail: pradipr@barc.gov.in; Mishra, L.; Kewlani, H.; Mittal, K. C. [Accelerator and Pulse Power Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Patil, D. S. [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

    2014-03-15

    A high current electron cyclotron resonance proton ion source is designed and developed for the low energy high intensity proton accelerator at Bhabha Atomic Research Centre. The plasma discharge in the ion source is stabilized by minimizing the reflected microwave power using four stub auto tuner and magnetic field. The optimization of extraction geometry is performed using PBGUNS code by varying the aperture, shape, accelerating gap, and the potential on the electrodes. While operating the source, it was found that the two layered microwave window (6 mm quartz plate and 2 mm boron nitride plate) was damaged (a fine hole was drilled) by the back-streaming electrons after continuous operation of the source for 3 h at beam current of 20–40 mA. The microwave window was then shifted from the line of sight of the back-streaming electrons and located after the water-cooled H-plane bend. In this configuration the stable operation of the high current ion source for several hours is achieved. The ion beam is extracted from the source by biasing plasma electrode, puller electrode, and ground electrode to +10 to +50 kV, −2 to −4 kV, and 0 kV, respectively. The total ion beam current of 30–40 mA is recorded on Faraday cup at 40 keV of beam energy at 600–1000 W of microwave power, 800–1000 G axial magnetic field and (1.2–3.9) × 10{sup −3} mbar of neutral hydrogen gas pressure in the plasma chamber. The dependence of beam current on extraction voltage, microwave power, and gas pressure is investigated in the range of operation of the ion source.

  17. Beam extraction and high stability operation of high current electron cyclotron resonance proton ion source

    International Nuclear Information System (INIS)

    A high current electron cyclotron resonance proton ion source is designed and developed for the low energy high intensity proton accelerator at Bhabha Atomic Research Centre. The plasma discharge in the ion source is stabilized by minimizing the reflected microwave power using four stub auto tuner and magnetic field. The optimization of extraction geometry is performed using PBGUNS code by varying the aperture, shape, accelerating gap, and the potential on the electrodes. While operating the source, it was found that the two layered microwave window (6 mm quartz plate and 2 mm boron nitride plate) was damaged (a fine hole was drilled) by the back-streaming electrons after continuous operation of the source for 3 h at beam current of 20–40 mA. The microwave window was then shifted from the line of sight of the back-streaming electrons and located after the water-cooled H-plane bend. In this configuration the stable operation of the high current ion source for several hours is achieved. The ion beam is extracted from the source by biasing plasma electrode, puller electrode, and ground electrode to +10 to +50 kV, −2 to −4 kV, and 0 kV, respectively. The total ion beam current of 30–40 mA is recorded on Faraday cup at 40 keV of beam energy at 600–1000 W of microwave power, 800–1000 G axial magnetic field and (1.2–3.9) × 10−3 mbar of neutral hydrogen gas pressure in the plasma chamber. The dependence of beam current on extraction voltage, microwave power, and gas pressure is investigated in the range of operation of the ion source

  18. CLUSTER observations of electron outflowing beams carrying downward currents above the polar cap by northward IMF

    Directory of Open Access Journals (Sweden)

    A. Teste

    2007-05-01

    Full Text Available Above the polar cap, at about 5–9 Earth radii (RE altitude, the PEACE experiment onboard CLUSTER detected, for the first time, electron beams outflowing from the ionosphere with large and variable energy fluxes, well collimated along the magnetic field lines. All these events occurred during periods of northward or weak interplanetary magnetic field (IMF.

    These outflowing beams were generally detected below 100 eV and typically between 40 and 70 eV, just above the photoelectron level. Their energy gain can be explained by the presence of a field-aligned potential drop below the spacecraft, as in the auroral zone. The careful analysis of the beams distribution function indicates that they were not only accelerated but also heated. The parallel heating is estimated to about 2 to 20 eV and it globally tends to increase with the acceleration energy. Moreover, WHISPER observed broadband electrostatic emissions around a few kHz correlated with the outflowing electron beams, which suggests beam-plasma interactions capable of triggering plasma instabilities.

    In presence of simultaneous very weak ion fluxes, the outflowing electron beams are the main carriers of downward field-aligned currents estimated to about 10 nA/m2. These electron beams are actually not isolated but surrounded by wider structures of ion outflows. All along its polar cap crossings, Cluster observed successive electron and ion outflows. This implies that the polar ionosphere represents a significant source of cold plasma for the magnetosphere during northward or weak IMF conditions. The successive ion and electron outflows finally result in a filamented current system of opposite polarities which connects the polar ionosphere to distant regions of the magnetosphere.

  19. A low-cost, accurate and non-intercepting continuous method for beam current measurements in a high-current ion implanter

    International Nuclear Information System (INIS)

    The development of a low-cost, accurate, non-intercepting continuous method for measuring the beam current in a high-current ion implanter is described. The method, named a differential current monitor, is based on the electric charge conservation principle, applied to the currents that flow in the implanter electrical system, due to the acceleration voltage applied to the ion beam and the leakage currents to ground. This method allows for continuous measurement of the ion beam current without intercepting it. Since its installation, it is possible to accurate measure ion beam currents from tens of μA to mA, which is the normal range for this type of system

  20. Development of the bunch-by-bunch beam current acquisition system at SSRF

    Institute of Scientific and Technical Information of China (English)

    HUANG Siting; LENG Yongbin; YAN Yingbing

    2009-01-01

    In this paper, we report the development of a bunch-by-bunch beam current acquisition system. Through a waveform-reconstruction algorithm, the system realizes high equivalent sampling rate with a relatively low inherent rate. Based on the EPICS environment, information communication with other systems can be achieved. Preliminary test results in commissioning the SSRF storage ring show that the system can reconstruct the beam waveform of single bunch, providing a convenient and reliable method for the top-up operation in the future.

  1. Emittance measurements of high current heavy ion beams using a single shot pepperpot system

    International Nuclear Information System (INIS)

    The new 1.4 MeV/u high current injector for the Unilac successfully commissioned in 1999 is now accelerating heavy ions close to the calculated intensities. For example an 40Ar1+ beam with 8 emA allows to fill the GSI synchrotron to its inherent intensity limit. For emittance measurements of such intense beams a single shot pepperpot system has been developed. An overview of the hard- and software including mathematical algorithms is given. Results of emittance measurements at different intensities and energies are presented. The influence of stripping and related space charge effects on the emittance could be investigated

  2. Current control of the electron beam formed in the magnetron gun with a secondary-emission cathode

    International Nuclear Information System (INIS)

    Data are reported on electron beam generation and beam current control in two types of secondary-emission cathode magnetron guns. The influence of the magnetic field value and field distribution on the formation of the beam and its parameters has been investigated in the electron energy range between 20 and 150 keV. The influence of local magnetic field variations on the cathode and the electron beam characteristics has been studied. The possibility to control the electron beam current in various ways has been demonstrated

  3. Initiation of furazanotetrazinedioxide and mixes on its basis by high-current electron beam

    International Nuclear Information System (INIS)

    The results of study of physicochemical processes developing in the samples of furazanotetrazinedioxide (FTDO) and its mixes with dinitrodiazapentane (DNP) upon irradiation by the high-current electron beam with the energy density varied in the range of 0.05-60 J/cm2 are presented. Pre-explosion processes taking place in materials under examination at below threshold modes of excitation are studied. Electron beam threshold energy densities leading to explosive decomposition of FTDO and FTDO/DNP mixes are determined. Noticeable effect of the electron beam energy density on kinetic characteristics of explosive decomposition process of FTDO is discovered. Spectra of the products of FTDO explosive decomposition are measured at explosion initiation in the atmosphere

  4. Shaping of shock wave in aerogel irradiated by high-current pulsed electron beam

    International Nuclear Information System (INIS)

    Spread of pressure jumps excited by high-current pulsed electron beam in 0.025-0.25 g/cm3 density SiO2 aerogel was studied using laser differential interferometers and optical techniques. At the aerogel target rear side one recorded splittings-off and measured the rate of splitting fragment scattering. The rate of aerogel scattering towards the electron beam was determined. The parameters of the shock adiabat within aerogel porosity wide range were determined. The depth of the electron beam energy release zone depending on the aerogel density within 0.015-0.25 g/cm3 density range was determined experimentally. A model to describe high-porous materials was developed on the basis of the experimental data

  5. Issues concerning high current lower energy electron beams required for ion cooling between EBIS LINAC and booster

    Energy Technology Data Exchange (ETDEWEB)

    Hershcovitch,A.

    2009-03-01

    Some issues, regarding a low energy high current electron beam that will be needed for electron beam cooling to reduce momentum of gold ions exiting the EBIS LINAC before injection into the booster, are examined. Options for propagating such an electron beam, as well as the effect of neutralizing background plasma on electron and ion beam parameters are calculated. Computations and some experimental data indicate that none of these issues is a show stopper.

  6. High current H- ion sources for the large helical device neutral beam injector

    Science.gov (United States)

    Oka, Y.; Tsumori, K.; Takeiri, Y.; Kaneko, O.; Osakabe, M.; Asano, E.; Kawamoto, T.; Akiyama, R.

    1998-02-01

    Two large helical device-neutral beam injector (LHD-NBI) ion sources were fabricated and tested in the test stand for producing a beam of 180 keV×40 A with H- ions. They are Cesiated multicusp ion sources with a rectangular discharge chamber and a single stage multihole accelerator. These are scaled up from the 16 A H- ion sources in the National Institute for Fusion Science (NIFS). A plasma source with a high aspect ratio was operated stably with an arc power up to ˜300 kW for 10 s, after balancing of the electron emission from the filaments was made. A satisfactorily dense and uniform plasma without mode flip was produced. Electrons accompanied by H- ions were reduced by an extraction grid with the electron trap, instead of straight holes. The electron beam component caused by the stripping of electrons from H- ions was detected with an array of calorimeters at the bottom of the connecting duct. At the first stage of the test, one of the five segment grids of the accelerator was installed. An H- ion current of 5.5 A with a current density of 27.5 mA/cm2 for 0.6 s was obtained with an arc power of 135 kW with Cs introduction. A high arc power efficiency for H- ions was observed. The intense cusp field is considered to be the important factor to improve this. The beam divergence angle at 10.4 m downstream was ˜10 mrad. Since these results satisfied our design, a full segment accelerator was tested in the next stage. Beam conditioning for five segment grids is underway. So far, an H- current of 21.0 A has been obtained at 106 keV for 0.6 s. As a result, we had good prospects for achieving the full specification of LHD-NBI ion sources, especially for achieving higher current and focused beam as well as for long pulse. The neutral beam injection experiment for the LHD is scheduled to start in the middle of 1998.

  7. Comparison of Parmela and MAFIA Simulations of Beam Dynamics in High Current Photoinjector

    CERN Document Server

    Kurennoy, Sergey S

    2004-01-01

    A high-current RF photoinjector producing low-emittance electron beam is an important technology for high-power CW FEL. LANL-AES team designed a 2.5-cell, pi-mode, 700-MHz normal-conducting RF photoinjector with magnetic emittance compensation. With the electric field gradients of 7, 7, and 5 MV/m in the three subsequent cells, the photoinjector will produce a 2.5-MeV electron beam with 3-nC charge per bunch and the transverse rms emittance 7 mm-mrad. Beam dynamics in the photoinjector has been modeled in details. In addition to the usual approach, with fields calculated by Superfish-Poisson and beam simulations performed by Parmela, we also used MAFIA group of codes, both to calculate cavity fields and to model beam dynamics with its particle-in-cell module TS. The second way naturally includes wake-field effects into consideration. The simulation results and comparison between two approaches will be presented.

  8. Proceedings of the 1979 workshop on beam current limitations in storage rings, July 16-27, 1979

    International Nuclear Information System (INIS)

    The Workshop on Beam Current Limitations in Storage Rings was held at Brookhaven National Laboratory from July 16 to 27, 1979. The purpose of this Workshop was to discuss the physical mechanisms limiting the beam current or current density in accelerators or storage rings. Many of these machines are now being built or planned for a variety of applications, such as colliding beam experiments, synchrotron light production, heavy ion beams. This diversity was reflected in the Workshop and in the papers which have been contributed to these Proceedings. The twenty-one papers from the workshop were incorporated individually in the data base

  9. The Device to Measure Currents in External Beam Transportation Lines of the DC-72 Cyclotron

    CERN Document Server

    Gulbekyan, G G; Gall, A; Kalagin, I V; Timoshenko, G N; Pachadzhiev, K K

    2002-01-01

    The present work is devoted to the development of a device to measure ion currents in external beam transportation lines of the DC-72 cyclotron, which is being created for the Cyclotron Centre of the Slovak Republic. The device is based on a Faraday cup. As possible constructive materials for the Faraday cup, Al, Cu, Fe, W and C were considered from the point of view of both the residual radiation and heating by the proton beam of the 3 kW power. Based on the calculations performed. It was suggested to use aluminium. The results of calculations of the temperature distribution in cylindrical and conic cups have been presented, both for a proton energy of 30 MeV at a beam power of 3 kW, and for a proton energy of 72 MeV at a beam power of 2.5 kW. Also presented are the results of calculation of the construction with permanent magnets that create sufficient magnetic field to eliminate the influence of secondary electrons emission on the current measurement accuracy. As a result, a sketch of the device constructi...

  10. Design, fabrication, and testing of superconducting RF cavities for high average beam currents

    Science.gov (United States)

    Meidlinger, David Joseph

    For high current applications, it is desirable for the cavity shape to have a low longitudinal loss factor and to have a high beam-breakup threshold current. This dissertation describes three different cavities designed for this purpose: a six-cell elliptical cavity for particles traveling at the speed of light, a two-cell elliptical cavity for subluminal particle speeds, and a single cell cavity which uses the TM012 mode for acceleration. SUPERFISH simulations predict the peak fields in both of the elliptical cavities will not exceed the TeSLA values by more than 10% but both will have 28.7% larger apertures. The elliptical designs assume the bunch frequency equals the accelerating mode frequency. The beam pipe radius is chosen so that the cutoff frequency is less than twice that of the accelerating mode. Hence all of the monopole and dipole higher-order modes (HOMs) that can be driven by a Fourier component of the beam have low loaded Q values. This simplifies the problem of HOM damping. The TM012 cavity is predicted to have much higher peak fields than a pi-mode elliptical cavity, but offers potential advantages from its simplified shape; it is essentially a circular waveguide with curved end plates. This basic shape results in easier fabrication and simplified tuning. Two prototype two-cell cavities were fabricated and tested at cryogenic temperatures without beam.

  11. Single-beam measurements of LHC instability threshold in terms of octupole current

    CERN Document Server

    Mounet, N; Buffat, X; Burov, A; Hemelsoet, G; Metral, E; Papotti, G; Pieloni, T; Pojer, M; Salvant, B; Trad, G

    2012-01-01

    This note summarizes two machine development (MD) studies aimed at determining the octupole current needed in the LHC in order to stabilize all headtail instabilities at 4TeV/c, before and after the squeeze, with tight collimator settings, and when a single beam (beam 2) at maximum intensity (1380 bunches, 2.1 1014 protons) is present in the machine. The MDs followed the normal physics operation procedure, at the notable exception that a single beam was used, the other beam containing only one non-colliding nominal bunch. Octupole current (with negative polarity in the focusing octupoles and the opposite in the defocusing ones) was decreased by small steps until the instability threshold was reached. This was performed in two distinct MDs, one before the squeeze and the other after it, testing also several chromaticity values and the effect of the transverse damper in the latter case. Octupole thresholds are shown in each case studied, as well as the rise times of the instabilities observed.

  12. Reduction of beam current noise in the FNAL magnetron ion source

    Energy Technology Data Exchange (ETDEWEB)

    Bollinger, D. S., E-mail: bollinger@fnal.gov; Karns, P. R., E-mail: karns@fnal.gov; Tan, C. Y., E-mail: cytan@fnal.gov [Fermi National Accelerator Laboratory, Proton Source Department, P.O. Box 500, Batavia, Illinois (United States)

    2015-04-08

    The new FNAL Injector Line with a circular dimple magnetron ion source has been operational since December of 2012. Since the new injector came on line there have been variations in the H- beam current flattop observed near the downstream end of the Linac. Several different cathode geometries including a hollow cathode suggested by Dudnikov [1] were tried. Previous studies also showed that different mixtures of hydrogen and nitrogen had an effect on beam current noise [2]. We expanded on those studies by trying mixtures ranging from (0.25% nitrogen, 99.75% hydrogen) to (3% nitrogen, 97% hydrogen). The results of these studies in our test stand will be presented in this paper.

  13. A Conserved Vector Current test using low energy beta-beams

    OpenAIRE

    Balantekin, A. B.; de Jesus, J. H.; Lazauskas, R.; Volpe, C.

    2006-01-01

    We discuss the possibility of testing the weak currents and, in particular, the weak magnetism term through the measurement of the electron anti-neutrinos capture by protons at a low energy beta-beam facility. We analyze the sensitivity using both the total number of events and the angular distribution of the positrons emitted in a water Cerenkov detector. We show that the weak magnetism form factor might be determined with better than several percent accuracy using the angular distribution. ...

  14. Measurement of current density distribution in shaped e-beam writers

    Czech Academy of Sciences Publication Activity Database

    Horáček, Miroslav; Bok, Jan; Kolařík, Vladimír; Urbánek, Michal; Matějka, Milan; Krátký, Stanislav

    Praha: Czechoslovak Microscopy Society, 2014. ISBN 978-80-260-6720-7. [International Microscopy Congres /18./. Praha (CZ), 07.09.2014-12.09.2014] R&D Projects: GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01; GA TA ČR TE01020118 Institutional support: RVO:68081731 Keywords : e-beam writer * current density Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  15. Aluminum surface coating of copper using high-current electron beam

    International Nuclear Information System (INIS)

    High-current electron beam irradiation has been applied for surface coating of copper with aluminum in ablative mode at the TEMP-A accelerator with energy of 350 keV, pulse length of 5 μs, and fluence 10...200 J/cm2. The aluminum-rich surface layer with average thickness around 25 μm, microhardness of 6.7 GPa and elasticity modulus of 122 GPa was formed on the copper template.

  16. Charged current disappearance measurements in the NuMI off-axis beam

    Energy Technology Data Exchange (ETDEWEB)

    R. H. Bernstein

    2003-09-25

    This article studies the potential of combining charged-current disappearance measurements of {nu}{sub {mu}} {yields} {nu}{sub {tau}} from MINOS and an off-axis beam. The author finds that the error on {Delta}m{sup 2} from a 100 kt-yr off-axis measurement is a few percent of itself. Further, the author found little improvement to an off-axis measurement by combining it with MINOS.

  17. Beam optics of a 10-cm diameter high current heavy ion diode

    International Nuclear Information System (INIS)

    Typically a large diameter surface ionization source is used to produce > 0.5 A K+ current with emittance < 1 π-mm-mrad for heavy ion fusion experiments. So far we have observed aberrations that are slightly different from those predicted by computer simulations. We have now set up an experiment to study in detail the beam optics of such a large diameter ion diode and to benchmark the simulation code

  18. Study on Nanostructures Induced by High-Current Pulsed Electron Beam

    OpenAIRE

    Bo Gao; Yi Hao; Ganfeng Tu; Wenyuan Wu

    2012-01-01

    Four techniques using high-current pulsed electron beam (HCPEB) were proposed to obtain surface nanostructure of metal and alloys. The first method involves the distribution of several fine Mg nanoparticles on the top surface of treated samples by evaporation of pure Mg with low boiling point. The second technique uses superfast heating, melting, and cooling induced by HCPEB irradiation to refine the primary phase or the second phase in alloys to nanosized uniform distributed phases in the ma...

  19. Open-loop correction for an eddy current dominated beam-switching magnet

    International Nuclear Information System (INIS)

    A beam-switching magnet and the pulsed power supply it requires have been developed for the Japan Proton Accelerator Research Complex. To switch bunched proton beams, the dipole magnetic field must reach its maximum value within 40 ms. In addition, the field flatness should be less than 5 × 10−4 to guide each bunched beam to the designed orbit. From a magnetic field measurement by using a long search coil, it was found that an eddy current in the thick endplates and laminated core disturbs the rise of the magnetic field. The eddy current also deteriorates the field flatness over the required flat-top period. The measured field flatness was 5 × 10−3. By using a double-exponential equation to approximate the measured magnetic field, a compensation pattern for the eddy current was calculated. The integrated magnetic field was measured while using the newly developed open-loop compensation system. A field flatness of less than 5 × 10−4, which is an acceptable value, was achieved

  20. Coupling between eddy current and deflection in cantilevered beams in magnetic fields

    International Nuclear Information System (INIS)

    Experiments were performed to investigate the coupling between eddy currents and deflection in cantilevered beams in longitudinal and transverse magnetic fields. This coupling effect reduces the current, deflection, and material stress to levels far less severe than would be predicted if coupling is disregarded. The experiments were conducted using the FELIX (Fusion ELectromagnetic Induction experiment) facility at the Argonne National Laboratory. The beams, which provide a simple model for the limiter blades in a tokamak fusion reactor, are subjected to crossed time-varying and constant magnetic fields. The time-varying field simulates the decaying field during a plasma disruption and the constant field models the toroidal field. Several test pieces are employed to allow variations in thicknesses and mechanical and electrical properties. Various magnetic field levels and decay time constants of time-varying are used to study the extent of the coupling from weak to strong coupling. The ratios of constant field to time-varying field are kept in the range from 10:1 to 20:1 as would be appropriate to tokamak limiters. Major parameters measured as functions of time are beam deflection, measured with an electro-optical device; total circulating current, measured with a Rogowski coil; strain recorded by strain gauges; and magnetic fields measured with Hall probes

  1. Fast wave current drive in neutral beam heated plasmas on DIII-D

    International Nuclear Information System (INIS)

    The physics of non-inductive current drive and current profile control using the fast magnetosonic wave has been demonstrated on the DIII-D tokamak. In non-sawtoothing discharges formed by neutral beam injection (NBI), the radial profile of the fast wave current drive (FWCD) was determined by the response of the loop voltage profile to co, counter, and symmetric antenna phasings, and was found to be in good agreement with theoretical models. The application of counter FWCD increased the magnetic shear reversal of the plasma and delayed the onset of sawteeth, compared to co FWCD. The partial absorption of fast waves by energetic beam ions at high harmonics of the ion cyclotron frequency was also evident from a build up of fast particle pressure near the magnetic axis and a correlated increase in the neutron rate. The anomalous fast particle pressure and neutron rate increased with increasing NBI power and peaked when a harmonic of the deuterium cyclotron frequency passed through the center of the plasma. The experimental FWCD efficiency was highest at 2 T where the interaction between the fast waves and the beam ions was weakest; as the magnetic field strength was lowered, the FWCD efficiency decreased to approximately half of the maximum theoretical value

  2. Exploring the sheet resistance variation with various beam current densities in low-energy ion implantation

    International Nuclear Information System (INIS)

    The effect of ion beam current density, varied from 0.2 to 0.5 mA/cm2, on electrical characteristics of the shallow junction is investigated. Given an implant energy at 10 keV and a constant phosphorus ion dose of 2.25 x 1015 cm-2, the sheet resistance of the implanted Si after rapid thermal annealing (RTA) increases (from 66 to 70 Ω/sq) with increasing beam current density. To investigate the sheet resistance variation, thermal wave, cross-sectional transmission electron microscopy and secondary ion mass spectrometry (SIMS) are conducted. These analyses identify that dose rate and dose shift are the factors relating to the sheet resistance variation. SIMS depth profiles of phosphorous, before and after RTA annealing, reveal that implantation with higher beam current density leads to a smaller integrated dose. It is also found that dose rate induced crystal damage has no effect on the sheet resistance variation. The cause of dose shift is explored and it should arise from the neutralized ion species which are not detected by the Faraday cup

  3. Review of the neutral-beam current requirements for the Mirror Fusion Test Facility (MFTF)

    International Nuclear Information System (INIS)

    The techniques used to evaluate the beam-current requirements for MFTF are similar to those in previous studies but incorporate some improvements. In particular, we have enlarged the radial code BUILDUP to allow for a smaller radial grid and to improve the numerical accuracy; we have also improved the model of the atomic physics processes and the particle-equilibrium calculations. Also, a model of plasma containment that conserves energy as well as particles but does not include any effect of the expected drift-cyclotron loss-cone (DCLC) turbulence has been incorporated into the previous studies. We show that the DCLC turbulence increases the average ion energy and decreases the particle confinement time. Because these effects cancel to first order, the beam-current requirements are independent of the turbulence. We find that 24 of the present LBL source modules would sustain a plasma with an average beta of 0.46. This figure is within 10% of the MFTF goal and is within our calculational accuracies. We further show that the beam-current requirements for the large-diameter plasma are consistent with those of experiments to study the buildup of a field-reversed plasma

  4. Effects of current on early stages of focused ion beam nano-machining

    OpenAIRE

    Sabouri, Aydin; Anthony, Carl J.; Prewett, Philip D.; Bowen, James; Butt, Haider

    2015-01-01

    In this report we investigate the effects of focused ion beam machining at low doses in the range of 1015–1016 ions cm-2 for currents below 300 pA on Si(100) substrates. The effects of similar doses with currents in the range 10–300 pA were compared. The topography of resulting structures has been characterized using atomic force microscope, while crystallinity of the Si was assessed by means of Raman spectroscopy. These machining parameters allow a controllable preparation of structures eith...

  5. Amps particle accelerator definition study

    Science.gov (United States)

    Sellen, J. M., Jr.

    1975-01-01

    The Particle Accelerator System of the AMPS (Atmospheric, Magnetospheric, and Plasmas in Space) payload is a series of charged particle accelerators to be flown with the Space Transportation System Shuttle on Spacelab missions. In the configuration presented, the total particle accelerator system consists of an energetic electron beam, an energetic ion accelerator, and both low voltage and high voltage plasma acceleration devices. The Orbiter is illustrated with such a particle accelerator system.

  6. Numerical simulation of the processes of small-diameter high-current electron beam shaping and injection

    CERN Document Server

    Gordeev, V S; Myskov, G A

    2001-01-01

    With the aid of BEAM 25 program there was carried out the numerical simulation of the non-stationary process of shaping a small-diameter (<= 20mm) high-current hollow electron beam in a diode with magnetic insulation,as well as of the process of beam injection into the accelerating LIA track. The diode configuration for the purpose of eliminating the leakage of electron flux to the anode surface was update. Presented are the results of calculation of the injected beam characteristics (amplitude-time parameters of a current pulse, space-angle distributions of electrons etc.) depending on diode geometric parameters.

  7. Numerical simulation of the processes of small-diameter high-current electron beam shaping and injection

    International Nuclear Information System (INIS)

    With the aid of BEAM 25 program there was carried out the numerical simulation of the non-stationary process of shaping a small-diameter (≤ 20mm) high-current hollow electron beam in a diode with magnetic insulation,as well as of the process of beam injection into the accelerating LIA track. The diode configuration for the purpose of eliminating the leakage of electron flux to the anode surface was update. Presented are the results of calculation of the injected beam characteristics (amplitude-time parameters of a current pulse, space-angle distributions of electrons etc.) depending on diode geometric parameters

  8. Determination of reversed plasma current profile from the experiments of magnetic compression of a microsecond relativistic electron beam

    International Nuclear Information System (INIS)

    Measuring technique for distribution of reversed plasma current in relativistic electron beam crosssection which is based on velocity measurement of azimutj rotation of the beam spreading within the external magnetic field is realized experimentally. Measurements of reversed current profile are carried out during the experiments on magnetic compression of powerful microsecond relativistic electron beam (1 MV, 75 kA, 4μs, 100kj, 5 kA/cm2). Data on the level of beam charged neutralization at gas lowpressure in drift chamber are obtained

  9. Radiation induced currents in parallel plate ionization chambers: Measurement and Monte Carlo simulation for megavoltage photon and electron beams

    International Nuclear Information System (INIS)

    Polarity effects in ionization chambers are caused by a radiation induced current, also known as Compton current, which arises as a charge imbalance due to charge deposition in electrodes of ionization chambers. We used a phantom-embedded extrapolation chamber (PEEC) for measurements of Compton current in megavoltage photon and electron beams. Electron contamination of photon beams and photon contamination of electron beams have a negligible effect on the measured Compton current. To allow for a theoretical understanding of the Compton current produced in the PEEC effect we carried out Monte Carlo calculations with a modified user code, the COMPTON/EGSnrc. The Monte Carlo calculated COMPTON currents agree well with measured data for both photon and electron beams; the calculated polarity correction factors, on the other hand, do not agree with measurement results. The conclusions reached for the PEEC can be extended to parallel-plate ionization chambers in general

  10. Proton implanted silicon wafers investigated by electron beam induced current measurements

    International Nuclear Information System (INIS)

    Full text: Electron Beam Induced Current (EBIC) is an analysis method used in a Scanning Electron Microscope (SEM) to investigate buried junctions or defects in semiconductors. During an EBIC measurement, the electron beam enters a semiconductor and generates electron-hole pairs. If the charge carriers diffuse into a region where there is a built-in electric eld, such as a pn junction or a Schottky contact, charge separation will occur and a current will flow. This is similar to what happens in a solar cell except in an EBIC measurement the electron-hole pairs are generated by the electron beam instead of by light. We have used EBIC to investigate proton implanted silicon wafers with implantation doses from 1 x 1013 p+/cm2 to 1 x 1015 p+/cm2 and with implantation energies from 500 keV to 5 MeV. The implantation introduces vacancies, silicon interstitials, and hydrogen into the crystal. The sample is then annealed in the temperature range from room temperature to 10000C and defect complexes form. The microscopic structure of these defect complexes is not completely understood. There is a class of oxygen-vacancy defect complexes called thermal donors that are known to act as donors in silicon. Since electron-hole pairs recombine at defects, the EBIC signal is decreased if the charge carriers have to diffuse past defects on their way to the measurement contacts. (author)

  11. Benchmarking of neutral beam current drive codes as a basis for the integrated modelling for ITER

    International Nuclear Information System (INIS)

    Neutral beam injection is a robust method for heating and current drive because it does not depend on any resonance conditions or coupling conditions at the edge. High-energy neutral beam current drive (NBCD) was experimentally validated for central current drive in JT-60U, giving a further confidence in ITER predictions. Recent progress in diagnostics, equilibrium solvers and analysis techniques enable rather detailed comparisons with NBCD codes. However, different codes give somewhat different results. Thus, we need to clarify physics implementations in NBCD codes, such as the beam model, ionization process, fast ion diffusion in the velocity space, orbit effects and electron shielding. Also from an integrated modelling viewpoint, an NBCD code benchmark is needed to establish a more solid basis for ITER operations. A benchmark of the Fokker-Planck code ACCOME has been performed against the orbit following Monte-Carlo code OFMC. Although calculated profiles agree rather well, the OFMC profile is slightly wider than the ACCOME one. The difference in the total fast ion current is ∼ 15%. We have examined fast ion diffusion in the 2D velocity space and observed difference in the diffusion in the pitch angle space. We have also examined orbit effects using a point source of the fast ions. Comparison of OFMC runs with and without the drift term in the orbit equation shows the finite banana width effect is not negligible. We have started a new NBCD code benchmark in the frame of the ITPA Steady-State Operation Topical Group with Fokker-Planck codes and orbit following Monte-Carlo codes such as OFMC, ACCOME, SPOT, NEMO, ASTRA, TRANSP/NUBEAM, ONETWO/NUBEAM, DRIFT and TOPICS. (author)

  12. Measurements of beam current density and proton fraction of a permanent-magnet microwave ion source

    Energy Technology Data Exchange (ETDEWEB)

    Waldmann, Ole; Ludewigt, Bernhard [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States)

    2011-11-15

    A permanent-magnet microwave ion source has been built for use in a high-yield, compact neutron generator. The source has been designed to produce up to 100 mA of deuterium and tritium ions. The electron-cyclotron resonance condition is met at a microwave frequency of 2.45 GHz and a magnetic field strength of 87.5 mT. The source operates at a low hydrogen gas pressure of about 0.15 Pa. Hydrogen beams with a current density of 40 mA/cm{sup 2} have been extracted at a microwave power of 450 W. The dependence of the extracted proton beam fraction on wall materials and operating parameters was measured and found to vary from 45% for steel to 95% for boron nitride as a wall liner material.

  13. Use of heavy current nanosecond electron beams for the surface sterilization purposes

    International Nuclear Information System (INIS)

    Peculiarities of radiation effect of heavy-current pulse electron beams of nanosecond durability are studied for sterilization of several types of microorganisms, namely Bacillus subtilis, Bacillus pseudoanthraris, Staphylococcus albus Staphylococcus aureus, Sarcina lutea, Vibrio fluorescens. Radiation source had the following parameters: electron energy in the beam of 150 keV pulse durability of 10 ns frequency of pulse ranning of 10 Hz. Main results, reflecting minimum doze, necessary for 100% death of various-type microorganisms in dependence on density of bacterial suspension, are presented. It is shown that total decrease of lethal doze for bacteria of all types is explained by accessability of penetration of air oxygen in physiological solution with cells, being in fine (of several microns) surface layer of crops

  14. Current experiments using polarized beams of the JINR LHE accelerator complex

    International Nuclear Information System (INIS)

    The present review is devoted to the spin-dependent experiments carried out or prepared at the JINR LHE Synchrocyclotron. The acceleration of polarized deuterons, and experiments using the internal targets, the beam extraction and the polarimetry are briefly described. Then, representative experiments using either the extracted deuteron beam or secondary beams of polarized nucleons produced by polarized deuterons are treated. Three current experiments: 'DELTA-SIGMA', 'DELTA' and 'pp-SINGLET', require the polarized nucleon beams in conjunction with the Dubna polarized proton target. Already available ΔσL(np) results from the first experiment show unexpected energy dependence. Experiment 'DELTA' should investigate the nucleon strangeness. The aim of the third experiment is to study a possible resonant behavior of the spin-singlet pp scattering amplitude. For all other Dubna experiments unpolarized nucleon or nuclei targets are used. The polarized deuteron beam allows determining spin-dependent observable necessary for understanding the deuteron structure, as well as the nucleon substructure. One part of investigations concerns deuteron break-up reactions and deuteron proton backward elastic scattering. A considerable amount of data was obtained in this domain. Another part is dedicated to the measurements of the same spin-dependent observable in a 'cumulative' region. Interesting results were obtained for proton or pion productions in inclusive and semi-inclusive measurements. In the field of inelastic deuteron reactions, the analyzing power measurements were performed in the region covering Roper resonances. Many existing models are in disagreement with observed momentum dependences of different results. Finally, the proton-carbon analyzing power measurements extended the momentum region of rescattering observables. Some inclusive Dubna results are compared to exclusive Saclay data, and to lepton-deuteron measurements. Most of the JINR LHE experiments are carried

  15. Determination of the ReA Electron Beam Ion Trap electron beam radius and current density with an X-ray pinhole camera.

    Science.gov (United States)

    Baumann, Thomas M; Lapierre, Alain; Kittimanapun, Kritsada; Schwarz, Stefan; Leitner, Daniela; Bollen, Georg

    2014-07-01

    The Electron Beam Ion Trap (EBIT) of the National Superconducting Cyclotron Laboratory at Michigan State University is used as a charge booster and injector for the currently commissioned rare isotope re-accelerator facility ReA. This EBIT charge breeder is equipped with a unique superconducting magnet configuration, a combination of a solenoid and a pair of Helmholtz coils, allowing for a direct observation of the ion cloud while maintaining the advantages of a long ion trapping region. The current density of its electron beam is a key factor for efficient capture and fast charge breeding of continuously injected, short-lived isotope beams. It depends on the radius of the magnetically compressed electron beam. This radius is measured by imaging the highly charged ion cloud trapped within the electron beam with a pinhole camera, which is sensitive to X-rays emitted by the ions with photon energies between 2 keV and 10 keV. The 80%-radius of a cylindrical 800 mA electron beam with an energy of 15 keV is determined to be r(80%) = (212 ± 19)μm in a 4 T magnetic field. From this, a current density of j = (454 ± 83)A/cm(2) is derived. These results are in good agreement with electron beam trajectory simulations performed with TriComp and serve as a test for future electron gun design developments. PMID:25085129

  16. Effect of the electrostatic plasma lens on the emittance of a high-current heavy ion beam

    International Nuclear Information System (INIS)

    We describe measurements we have made of the emittance of a high-current, moderate-energy ion beam after transport through a permanent-magnet electrostatic plasma lens. The results indicate the absence of emittance growth due to the lens, when the lens is adjusted for optimal beam focusing. The measured emittance for a 16 keV Cu2+ ion beam formed by a vacuum arc ion source was about 0.4 π · mm · mrad at a beam current of 50 mA rising more-or-less linearly to 1.5 π · mm · mrad at 250 mA, and was conserved in beam transport through the lens. These results have significance for the application of high-current ion sources and the electrostatic plasma lens to particle accelerator injection

  17. Beam Effects from an Increase of LINAC Current from 40 ma to 49 Milliamperes

    Energy Technology Data Exchange (ETDEWEB)

    Ray Tomlin

    2002-06-05

    On March 25, 2002 the FNAL Linac had been running at a decreased 40 ma of beam current for some time. Both the 400 MeV Linac and the 8GeV Booster had been tuned to optimum running during that time. Optimum running for the Booster was at 4.1e12 per pulse. Losses at injection and at transition were limiting intensity at the time. By March 26, 2002 the Linac beam current had been increased to 49 ma. The optimum Booster intensity immediately jumped to 4.5e12 per pulse and increased in the next few days to 4.8e12 and 5e12 per pulse. Booster was not retuned until early April when a low-loss 5.0e12 was obtained for stacking operations. Linac current had sagged to 47 ma by then. Measurements were made on the 25th at 40 ma and the 26th and 27th at 49 ma. This is a report and discussion of those measurements.

  18. Relation between beam driven seed-current and rotation in steady state FRC

    International Nuclear Information System (INIS)

    We consider an field steady state reversed configuration whose current is maintained by a steady state beam. Without quadrupole fields, back current can be inhibited by the Ohkawa effect if Z/sub b/ < Z/sub eff/, where Z/sub b/ and Z/sub eff/ are the beam charge number and effective charge number of background ions. However, the resulting rotation of the plasma often leads to instability. For systems, with a large bootstrap effect, the rotation can be moderate, but it is then difficult to contain fusion products. An additional problem is that the Ohkawa effect due to alpha particles tends to dissemble the equilibrium. It has previously been shown that the presence of a quadrupole field inhibit back current. Here we show that a steady state flux can be maintained with moderate input power in both reactors and present day experiments with the resulting rotation slow enough to fulfill stability conditions. However, experimental means must be devised to supply a continual source of particles and additional energy. 17 refs., 3 figs

  19. Volumetric strengthening of polycrystals of steel 110G13 with high-current electron beam

    International Nuclear Information System (INIS)

    Structural and phase states as well as mechanical properties are studied in manganese steel 110G13 irradiated by a low-energy (30-40 keV) high-current electron beam. The quantity of pulses with 2.5 μs duration and 10 s intervals constitutes from 1 to 10 s. Using metallographic, X-ray diffraction and electron microscopical methods it is shown that the irradiation results in bulk quasi-periodical hardening of specimens. Hardening effect increases with pulse amount. The zones of increased microhardness are characterized by high dislocation density and by occurrence of γ-ε transformation products

  20. High Current Proton and Deuteron Beams for Accelerators and Neutron Generators

    OpenAIRE

    Skalyga, V.; Izotov, I.; Razin, S.; Sidorov, A.; Golubev, S.; Maslennikova, A.; Volovecky, A.; Koivisto, Hannu; Tarvainen, Olli; Kalvas, Taneli

    2014-01-01

    This paper presents the latest results of high current proton and deuteron beam production at SMIS 37 facility at the Institute of Applied Physics (IAP RAS). In this experimental setup the plasma is created and the electrons are heated by 37.5 GHz gyrotron radiation with power up to 100 kW in a simple mirror trap fulfilling the ECR condition. High microwave power and frequency allow sustaining higher density hydrogen plasma (ne up to 2·1013 cm-3) in comparison to conve...

  1. Electron beam induced current measurement on a specimen biased in a cathode lens

    Czech Academy of Sciences Publication Activity Database

    Horáček, Miroslav; Zobač, Martin; Vlček, Ivan

    Graz : Verlag der Technischen Universität, 2009, Vol. 1: 211-212. ISBN 978-3-85125-062-6. [MC 2009 - Joint Meeting of Dreiländertagung and Multinational Congress on Microscopy /9./. Graz (AT), 30.08.2009-04.09.2009] R&D Projects: GA AV ČR IAA100650803 Institutional research plan: CEZ:AV0Z20650511 Keywords : elektron beam induced current * SEM * very low energy electrons * cathode lens * specimen bias Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering http://www.univie.ac.at/asem/Graz_MC_09/papers/77645.pdf

  2. High current, high energy proton beams accelerated by a sub-nanosecond laser

    Czech Academy of Sciences Publication Activity Database

    Margarone, Daniele; Krása, Josef; Picciotto, A.; Torrisi, L.; Láska, Leoš; Velyhan, Andriy; Prokůpek, Jan; Ryc, L.; Parys, P.; Ullschmied, Jiří; Rus, Bedřich

    2011-01-01

    Roč. 653, č. 1 (2011), s. 159-163. ISSN 0168-9002 R&D Projects: GA ČR(CZ) GAP205/11/1165; GA AV ČR IAA100100715; GA MŠk(CZ) 7E09092 Grant ostatní: FP 7 Extreme light infrastructure preparatory phase (ELI-PP)(XE) INFRA-2007-2.2-01 212105 Institutional research plan: CEZ:AV0Z10100523; CEZ:AV0Z20430508 Keywords : laser -acceleration * proton beam * high ion current * time-of-flight * proton energy distribution Subject RIV: BH - Optics, Masers, Laser s Impact factor: 1.207, year: 2011

  3. Positron annihilation and thermally stimulated current of electron beam irradiated polyetheretherketone

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, Shigetaka; Shinyama, Katsuyoshi; Baba, Makoto [Hachinohe Inst. of Tech., Hachinohe, Aomori (Japan); Suzuki, Takenori

    1997-03-01

    Positron lifetime measurements were applied to electron beam irradiated poly(ether-ether-ketone). The lifetime, {tau}{sub 3}, of the ortho-positronium of unirradiated and 5 MGy irradiated specimen became rapidly longer above about 150degC. {tau}{sub 3} of 50 MGy and 100 MGy irradiated specimen was shorter than that of unirradiated one. Thermally stimulated current (TSC) decreased with increasing the dose before voltage application. In the case of voltage application, a TSC peak appeared and the peak value decreased with increased the dose. The correlation between the results of positron annihilation and TSC was investigated. (author)

  4. Enhancement in ion beam current with layered-glows in a constricted dc plasma ion source

    International Nuclear Information System (INIS)

    High current mode has been discovered and investigated in a constricted dc plasma ion source. As discharge currents exceed a certain threshold, voltage to sustain the constricted dc plasma suddenly falls down to almost half of the value. In this sense, constricted dc plasmas can be sustained at much higher current than in conventional mode operation at a fixed discharge voltage. Phenomenally, several discrete layered-glows are created between an anode glow and a cathode glow. The layers are thin and divided by dark spaces where charged particles can be accelerated. In this high current mode, ion beam current density is about 100 times higher than in conventional mode at the same voltage. It is noteworthy that lower gas pressure is desirable to sustain the layered-glow mode, which is also profitable for ion source in terms of differential pumping. Ion current density exceeds 300 mA/cm2 at low discharge power of 175 W where ion density of plasma ball is estimated to be over 3.7x1012 cm-3.

  5. A high-current four-beam xenon ion source for heavy-ion fusion

    International Nuclear Information System (INIS)

    The growing interest in inertial confinement fusion using heavy ions has elicited from the Los Alamos Scientific Laboratory a proposal to use a multi-channel radiofrequency quadrupole (RFQ) structure for the initial stage of the heavy-ion accelerator. The RFQ would have 4 channels in each module and each channel would accelerate 25 mA of Xe+1. Based on experiments with xenon beam production with a high current duoPlGatron source at Chalk River Nuclear Laboratories, a 245 keV 4-beam xenon injector has been designed for this 4-channel RFQ. The injector is of modular design with 4 small independent plasma sources mounted in a 10 cm square array on a common combined extraction and acceleration column. The electrodes have 4 separate sets of apertures and each channel produces a 29 mA beam for injection into its corresponding RFQ channel. This paper presents a conceptual design for the injector, code calculations for the column electrode design and results of a preliminary test carried out to verify the feasibility of the concept. (author)

  6. Design and construction of 18 MeV electron linac for pico- and nano-second beam

    International Nuclear Information System (INIS)

    An electron linac which can accelerate pico- and nano-second beam with an energy of 18 MeV has been designed and constructed. The linac can accelerate picosecond beam with a pulse width of ∼ 10 ps and with an output charge of ∼ 1 nc. The linac can accelerate 10 ns beam with an output current of 2 amps. (author)

  7. Characterization of beam-driven instabilities and current redistribution in MST plasmas

    Science.gov (United States)

    Parke, E.

    2015-11-01

    A unique, high-rep-rate (>10 kHz) Thomson scattering diagnostic and a high-bandwidth FIR interferometer-polarimeter on MST have enabled characterization of beam-driven instabilities and magnetic equilibrium changes observed during high power (1 MW) neutral beam injection (NBI). While NBI leads to negligible net current drive, an increase in on-axis current density observed through Faraday rotation is offset by a reduction in mid-radius current. Identification of the phase flip in temperature fluctuations associated with tearing modes provides a sensitive measure of rational surface locations. This technique strongly constrains the safety factor for equilibrium reconstruction and provides a powerful new tool for measuring the equilibrium magnetic field. For example, the n = 6 temperature structure is observed to shift inward 1.1 +/- 0.6 cm, with an estimated reduction of q0 by 5%. This is consistent with a mid-radius reduction in current, and together the Faraday rotation and Thomson scattering measurements corroborate an inductive redistribution of current that compares well with TRANSP/MSTFit predictions. Interpreting tearing mode temperature structures in the RFP remains challenging; the effects of multiple, closely-spaced tearing modes on the mode phase measurement require further verification. In addition to equilibrium changes, previous work has shown that the large fast ion population drives instabilities at higher frequencies near the Alfvén continuum. Recent observations reveal a new instability at much lower frequency (~7 kHz) with strongly chirping behavior. It participates in extensive avalanches of the higher frequency energetic particle and Alfvénic modes to drive enhanced fast ion transport. Internal structures measured from Te and ne fluctuations, their dependence on the safety factor, as well as frequency scaling motivate speculation about mode identity. Work supported by U.S. DOE.

  8. High-resolution velocimetry in energetic tidal currents using a convergent-beam acoustic Doppler profiler

    Energy Technology Data Exchange (ETDEWEB)

    Sellar, Brian [Univ. of Edinburgh, Scotland (United Kingdom); Harding, Samuel F. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Richmond, Marshall C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-07-16

    An array of convergent acoustic Doppler velocimeters has been developed and tested for the high resolution measurement of three-dimensional tidal flow velocities in an energetic tidal site. This configuration has been developed to increase spatial resolution of velocity measurements in comparison to conventional acoustic Doppler profilers (ADPs) which characteristically use diverging acoustic beams emanating from a single instrument. This is achieved using converging acoustic beams with a sample volume at the focal point of 0.03 m3. The array is also able to simultaneously measure three-dimensional velocity components in a profile throughout the water column, and as such is referred to herein as a converging-beam acoustic Doppler profiler (CADP). Mid-depth profiling is achieved through integration of the sensor platform with the operational Alstom 1MW DeepGen-IV Tidal Turbine. This proof-of-concept paper outlines system configuration and comparison to measurements provided by co-installed reference instrumentation. Comparison of CADP to standard ADP velocity measurements reveals a mean difference of 8 mm/s, standard deviation of 18 mm/s, and order-of-magnitude reduction in realizable length-scale. CADP focal point measurements compared to a proximal single-beam reference show peak cross-correlation coefficient of 0.96 over 4.0 s averaging period and a 47% reduction in Doppler noise. The dual functionality of the CADP as a profiling instrument with a high resolution focal point make this configuration a unique and valuable advancement in underwater velocimetry enabling improved turbulence, resource and structural loading quantification and validation of numerical simulations. Alternative modes of operation have been implemented including noise-reducing bi-static sampling. Since waves are simultaneously measured it is expected that derivatives of this system will be a powerful tool in wave-current interaction studies.

  9. Optimization of a cryogenic current comparator for the application as beam monitor

    International Nuclear Information System (INIS)

    Aim of the present thesis was to improve by the application of new materials and concepts the noise-limited resolution as well as the band width of a cryogenic current comparator for the measurement of the time behavior of smallest beam currents, consisting of a superconducting meander-shaped screening, a superconducting pick-up coil, a superconducting matching transformer, and a SQID sensor, and to reduce its sensitivity against mechanical oscillations. because of this the present thesis deals with the systematic study of the magnetic properties of ferromagnetic materials and their noise contributions for the application in pick-up coils respectively transformers. The main topic of this thesis layed thereby on the characterization of novel amorphous as well as nanocrystalline materials at low temperatures, for which hitherto no reliable values were present in the literature.

  10. Experimental study on the generation and transmission of the high-current repetitive electron beam

    International Nuclear Information System (INIS)

    When vacuum electron diode is repetitively operated, it presents some peculiar characteristics. Because of its small screening radius and short delay time, graphite is chosen as the cathode material. In experiments, the following results were attained: (1) when the annular cathode is thinned or the repetitive rate is increased, because of thermal effect of current and quickening expanding speed of plasma, the consistency of pulses in a burst is worsened; (2) with the strength of guiding magnetic field increased, the plasma is more restricted and expand slower, and the total current, as well as the electron-emitting area is reduced and the impedance of diode is increased. At last, when the strength of guiding magnetic field is 1.5 T and the cathode is 1 mm thick, a uniform electron beam of 827 kV, 8.22 kA, 100 Hz is obtained. (authors)

  11. High-current density, high-brightness electron beams from large-area lanthanum hexaboride cathodes

    Science.gov (United States)

    Loschialpo, P.; Kapetanakos, C. A.

    1988-04-01

    Large diameter lanthanum hexaboride (LaB6) cathodes operated at 10 kV have produced 1-5-microsec electron pulses with current density between 10 and 20 A/sq cm. Normalized beam brightness, approximately 300,000 A/sq cm sq rad has been consistently measured. To obtain this high-current density, the LaB6 cathodes have been heated to temperatures between about 1600 and 1800 C. Very uniform temperature profiles are obtained by applying a carefully tailored electron bombardment heating power distribution. These measurements have been made between pressure 10 to the -6th to -10 to the -5th Torr, i.e., under much less demanding vacuum conditions than that required by conventional dispenser-type cathodes.

  12. High-current density, high-brightness electron beams from large-area lanthanum hexaboride cathodes

    International Nuclear Information System (INIS)

    Large (∼5 cm) diameter lanthanum hexaboride (LaB6) cathodes operated at 10 kV have produced 1--5-μs electron pulses with current density between 10 and 20 A/cm2. Normalized beam brightness, B/sub n/ = I/(πβγε)2, approximately 3 x 105 A/cm2 rad2 has been consistently measured. To obtain this high-current density, the LaB6 cathodes have been heated to temperatures between ∼1600 and 1800 0C. Very uniform temperature profiles are obtained by applying a carefully tailored electron bombardment heating power distribution. These measurements have been made between pressure 10-6--10-5 Torr, i.e., under much less demanding vacuum conditions than that required by conventional dispenser-type cathodes

  13. 10 Orders of Magnitude Current Measurement Digitisers for the CERN Beam Loss Systems

    CERN Document Server

    Vigano, W; Dehning, B; Kwiatkowski, M; Venturini, G G; Zamantzas, C

    2014-01-01

    A wide range current digitizer card is needed for the acquisition module of the beam loss monitoring systems in the CERN Injector Complex. The fully differential frequency converter allows measuring positive and negative input currents with a resolution of 31nA in an integration window of 2μs. Increasing the integration window, the dynamic range covers 2•1010 were the upper part of the range is converted by measuring directly the voltage drop on a resistor. The key elements of this design are the fully differential integrator and the switches operated by an FPGA. The circuit is designed to avoid any dead time in the acquisition and reliability and failsafe operational considerations are main design goals. The circuit will be discussed in detail and lab and field measurements will be shown.

  14. Structural transitions in electron beam deposited Co–carbonyl suspended nanowires at high electrical current densities

    Directory of Open Access Journals (Sweden)

    Gian Carlo Gazzadi

    2015-06-01

    Full Text Available Suspended nanowires (SNWs have been deposited from Co–carbonyl precursor (Co2(CO8 by focused electron beam induced deposition (FEBID. The SNWs dimensions are about 30–50 nm in diameter and 600–850 nm in length. The as-deposited material has a nanogranular structure of mixed face-centered cubic (FCC and hexagonal close-packed (HCP Co phases, and a composition of 80 atom % Co, 15 atom % O and 5 atom % C, as revealed by transmission electron microscopy (TEM analysis and by energy-dispersive X-ray (EDX spectroscopy, respectively. Current (I–voltage (V measurements with current densities up to 107 A/cm2 determine different structural transitions in the SNWs, depending on the I–V history. A single measurement with a sudden current burst leads to a polycrystalline FCC Co structure extended over the whole wire. Repeated measurements at increasing currents produce wires with a split structure: one half is polycrystalline FCC Co and the other half is graphitized C. The breakdown current density is found at 2.1 × 107 A/cm2. The role played by resistive heating and electromigration in these transitions is discussed.

  15. Structural transitions in electron beam deposited Co-carbonyl suspended nanowires at high electrical current densities.

    Science.gov (United States)

    Gazzadi, Gian Carlo; Frabboni, Stefano

    2015-01-01

    Suspended nanowires (SNWs) have been deposited from Co-carbonyl precursor (Co2(CO)8) by focused electron beam induced deposition (FEBID). The SNWs dimensions are about 30-50 nm in diameter and 600-850 nm in length. The as-deposited material has a nanogranular structure of mixed face-centered cubic (FCC) and hexagonal close-packed (HCP) Co phases, and a composition of 80 atom % Co, 15 atom % O and 5 atom % C, as revealed by transmission electron microscopy (TEM) analysis and by energy-dispersive X-ray (EDX) spectroscopy, respectively. Current (I)-voltage (V) measurements with current densities up to 10(7) A/cm(2) determine different structural transitions in the SNWs, depending on the I-V history. A single measurement with a sudden current burst leads to a polycrystalline FCC Co structure extended over the whole wire. Repeated measurements at increasing currents produce wires with a split structure: one half is polycrystalline FCC Co and the other half is graphitized C. The breakdown current density is found at 2.1 × 10(7) A/cm(2). The role played by resistive heating and electromigration in these transitions is discussed. PMID:26199833

  16. Current transport in ZnO/Si heterostructure grown by laser molecular beam epitaxy

    Institute of Scientific and Technical Information of China (English)

    Teng Xiao-Yun; Wu Yan-Hua; Yu Wei; Gao Wei; Fu Guang-Sheng

    2012-01-01

    The n-ZnO/p-Si heterojunction was fabricated by depositing high quality single crystalline aluminium-doped n-type ZnO film on p-type Si using the laser molecular beam epitaxy technique. The heterojunction exhibited a good rectifying behavior.The electrical properties of the heterojunction were investigated by means of temperature dependence current density-voltage measurements.The mechanism of the current transport was proposed based on the band structure of the heterojunction.When the applied bias V is lower than 0.15 V,the current follows the Ohmic behavior.When 0.15 V < V < 0.6 V,the transport property is dominated by diffusion or recombination in the junction space charge region,while at higher voltages (V > 0.6 V),the space charge limited effect becomes the main transport mechanism.The current-voltage characteristic under illumination was also investigated.The photovoltage and the short circuit current density of the heterojunction aproached 270 mV and 2.10 mA/cm2,respectively.

  17. Surface modification of Al-Pb alloy by high current pulsed electron beam

    Institute of Scientific and Technical Information of China (English)

    LU You; LI Shi-long; AN Jian; LIU Yong-bing

    2006-01-01

    Al-Pb alloy was modified by high current pulsed electron beam and the microstructure, hardness and tribological characteristics were characterized by scanning electron microscopy, electronic microanalysis probe microanalysis, Knoop hardness indentation and pin-on-disc type wear testing machine. The results show that the microstructure and hardness can be greatly improved, and the modification layer consists of a molten zone, an overlapped zone of heat-affected and quasistatic thermal stress-affected zone and a transition zone followed by the substrate. The tribological properties of high current pulsed electron beam irradiated Al-Pb alloy are correspondingly improved largely. Optical observation and scanning electron microscopy analysis reveal that the low wear rate and lowest level in coefficient of friction at high load level for irradiated Al-Pb alloy are due to the formation of a lubricious tribolayer covering the worn surface, which is a mixture of Al2O3, Pb3O4 and silicate. The wear mode varies from oxidative wear at low load to film spalling at high load and, finally, adhesive wear.

  18. Various categories of defects after surface alloying induced by high current pulsed electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Dian [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Tang, Guangze, E-mail: oaktang@hit.edu.cn [School of Material Science & Engineering, Harbin Institute of Technology, Harbin 150001 (China); Ma, Xinxin [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Gu, Le [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Sun, Mingren [School of Material Science & Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wang, Liqin [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2015-10-01

    Highlights: • Four kinds of defects are found during surface alloying by high current electron beam. • Exploring the mechanism how these defects appear after irradiation. • Increasing pulsing cycles will help to get good surface quality. • Choosing proper energy density will increase surface quality. - Abstract: High current pulsed electron beam (HCPEB) is an attractive advanced materials processing method which could highly increase the mechanical properties and corrosion resistance. However, how to eliminate different kinds of defects during irradiation by HCPEB especially in condition of adding new elements is a challenging task. In the present research, the titanium and TaNb-TiW composite films was deposited on the carburizing steel (SAE9310 steel) by DC magnetron sputtering before irradiation. The process of surface alloying was induced by HCPEB with pulse duration of 2.5 μs and energy density ranging from 3 to 9 J/cm{sup 2}. Investigation of the microstructure indicated that there were several forms of defects after irradiation, such as surface unwetting, surface eruption, micro-cracks and layering. How the defects formed was explained by the results of electron microscopy and energy dispersive spectroscopy. The results also revealed that proper energy density (∼6 J/cm{sup 2}) and multi-number of irradiation (≥50 times) contributed to high quality of alloyed layers after irradiation.

  19. High current density ion beam obtained by a transition to a highly focused state in extremely low-energy region

    Energy Technology Data Exchange (ETDEWEB)

    Hirano, Y., E-mail: y.hirano@aist.go.jp, E-mail: hirano.yoichi@phys.cst.nihon-u.ac.jp [Innovative Plasma Processing Group, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); College of Science and Technologies, Nihon University, Chiyodaku, Tokyo 101-0897 (Japan); Kiyama, S.; Koguchi, H. [Innovative Plasma Processing Group, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Fujiwara, Y.; Sakakita, H. [Innovative Plasma Processing Group, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Department of Engineering Mechanics and Energy, University of Tsukuba, Ibaraki 305-8577 (Japan)

    2015-11-15

    A high current density (≈3 mA/cm{sup 2}) hydrogen ion beam source operating in an extremely low-energy region (E{sub ib} ≈ 150–200 eV) has been realized by using a transition to a highly focused state, where the beam is extracted from the ion source chamber through three concave electrodes with nominal focal lengths of ≈350 mm. The transition occurs when the beam energy exceeds a threshold value between 145 and 170 eV. Low-level hysteresis is observed in the transition when E{sub ib} is being reduced. The radial profiles of the ion beam current density and the low temperature ion current density can be obtained separately using a Faraday cup with a grid in front. The measured profiles confirm that more than a half of the extracted beam ions reaches the target plate with a good focusing profile with a full width at half maximum of ≈3 cm. Estimation of the particle balances in beam ions, the slow ions, and the electrons indicates the possibility that the secondary electron emission from the target plate and electron impact ionization of hydrogen may play roles as particle sources in this extremely low-energy beam after the compensation of beam ion space charge.

  20. High current density ion beam obtained by a transition to a highly focused state in extremely low-energy region

    Science.gov (United States)

    Hirano, Y.; Kiyama, S.; Fujiwara, Y.; Koguchi, H.; Sakakita, H.

    2015-11-01

    A high current density (≈3 mA/cm2) hydrogen ion beam source operating in an extremely low-energy region (Eib ≈ 150-200 eV) has been realized by using a transition to a highly focused state, where the beam is extracted from the ion source chamber through three concave electrodes with nominal focal lengths of ≈350 mm. The transition occurs when the beam energy exceeds a threshold value between 145 and 170 eV. Low-level hysteresis is observed in the transition when Eib is being reduced. The radial profiles of the ion beam current density and the low temperature ion current density can be obtained separately using a Faraday cup with a grid in front. The measured profiles confirm that more than a half of the extracted beam ions reaches the target plate with a good focusing profile with a full width at half maximum of ≈3 cm. Estimation of the particle balances in beam ions, the slow ions, and the electrons indicates the possibility that the secondary electron emission from the target plate and electron impact ionization of hydrogen may play roles as particle sources in this extremely low-energy beam after the compensation of beam ion space charge.

  1. High current density ion beam obtained by a transition to a highly focused state in extremely low-energy region

    International Nuclear Information System (INIS)

    A high current density (≈3 mA/cm2) hydrogen ion beam source operating in an extremely low-energy region (Eib ≈ 150–200 eV) has been realized by using a transition to a highly focused state, where the beam is extracted from the ion source chamber through three concave electrodes with nominal focal lengths of ≈350 mm. The transition occurs when the beam energy exceeds a threshold value between 145 and 170 eV. Low-level hysteresis is observed in the transition when Eib is being reduced. The radial profiles of the ion beam current density and the low temperature ion current density can be obtained separately using a Faraday cup with a grid in front. The measured profiles confirm that more than a half of the extracted beam ions reaches the target plate with a good focusing profile with a full width at half maximum of ≈3 cm. Estimation of the particle balances in beam ions, the slow ions, and the electrons indicates the possibility that the secondary electron emission from the target plate and electron impact ionization of hydrogen may play roles as particle sources in this extremely low-energy beam after the compensation of beam ion space charge

  2. Experimental study of coupling between eddy currents and deflections in cantilevered beams as models of tokamak limiters

    International Nuclear Information System (INIS)

    The coupling between eddy current and motion in a cantilevered beam is examined. The beam, which provides a simple model for the limiter blades of a tokamak fusion reactor, was subjected to simultaneous orthogonal time-varying and constant magnetic fields. The dynamic deformation of the beam includes two different modes: a bending mode and a torsional mode. Interaction of current with each mode and with the combined modes of vibration in described. Experimental verification of the case without torsional motion was performed with the FELIX facility at ANL. The peak deflection and stresses are much less than those predicted without consideration given to the coupling

  3. Cathode performance during two beam operation of the high current high polarization electron gun for eRHIC

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, O. [Brookhaven National Lab. (BNL), Upton, NY (United States); Ben-Zvi, I. [Brookhaven National Lab. (BNL), Upton, NY (United States); Degen, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Gassner, D. M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Lambiase, R. [Brookhaven National Lab. (BNL), Upton, NY (United States); Meng, W. [Brookhaven National Lab. (BNL), Upton, NY (United States); Pikin, A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Rao, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Sheehy, B. [Brookhaven National Lab. (BNL), Upton, NY (United States); Skaritka, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wang, E. [Brookhaven National Lab. (BNL), Upton, NY (United States); Pietz, J. [Transfer Engineering and Manufacturing, Inc., Fremont, CA (United States); Ackeret, M. [Transfer Engineering and Manufacturing, Inc., Fremont, CA (United States); Yeckel, C. [Stangenes Industries, Palo Alto, CA (United States); Miller, R. [Stangenes Industries, Palo Alto, CA (United States); Dobrin, E. [Stangenes Industries, Palo Alto, CA (United States); Thompson, K. [Stangenes Industries, Palo Alto, CA (United States)

    2015-05-03

    Two electron beams from two activated bulk GaAs photocathodes were successfully combined during the recent beam test of the High Current High Polarization Electron gun for eRHIC. The beam test took place in Stangenes Industries in Palo Alto, CA, where the cathodes were placed in diagonally opposite locations inside the high voltage shroud. No significant cross talking between the cathodes was found for the pertinent vacuum and low average current operation, which is very promising towards combining multiple beams for higher average current. This paper describes the cathode preparation, transport and cathode performance in the gun for the combining test, including the QE and lifetimes of the photocathodes at various steps of the experiment.

  4. Electron beam dynamics in the long-pulse, high-current DARHT-II linear induction accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Ekdahl, Carl A [Los Alamos National Laboratory; Abeyta, Epifanio O [Los Alamos National Laboratory; Aragon, Paul [Los Alamos National Laboratory; Archuleta, Rita [Los Alamos National Laboratory; Cook, Gerald [Los Alamos National Laboratory; Dalmas, Dale [Los Alamos National Laboratory; Esquibel, Kevin [Los Alamos National Laboratory; Gallegos, Robert A [Los Alamos National Laboratory; Garnett, Robert [Los Alamos National Laboratory; Harrison, James F [Los Alamos National Laboratory; Johnson, Jeffrey B [Los Alamos National Laboratory; Jacquez, Edward B [Los Alamos National Laboratory; Mccuistian, Brian T [Los Alamos National Laboratory; Montoya, Nicholas A [Los Alamos National Laboratory; Nath, Subrato [Los Alamos National Laboratory; Nielsen, Kurt [Los Alamos National Laboratory; Oro, David [Los Alamos National Laboratory; Prichard, Benjamin [Los Alamos National Laboratory; Rowton, Lawrence [Los Alamos National Laboratory; Sanchez, Manolito [Los Alamos National Laboratory; Scarpetti, Raymond [Los Alamos National Laboratory; Schauer, Martin M [Los Alamos National Laboratory; Seitz, Gerald [Los Alamos National Laboratory; Schulze, Martin [Los Alamos National Laboratory; Bender, Howard A [Los Alamos National Laboratory; Broste, William B [Los Alamos National Laboratory; Carlson, Carl A [Los Alamos National Laboratory; Frayer, Daniel K [Los Alamos National Laboratory; Johnson, Douglas E [Los Alamos National Laboratory; Tom, C Y [Los Alamos National Laboratory; Williams, John [Los Alamos National Laboratory; Hughes, Thomas [Los Alamos National Laboratory; Anaya, Richard [LLNL; Caporaso, George [LLNL; Chambers, Frank [LLNL; Chen, Yu - Jiuan [LLNL; Falabella, Steve [LLNL; Guethlein, Gary [LLNL; Raymond, Brett [LLNL; Richardson, Roger [LLNL; Trainham, C [NSTEC/STL; Watson, Jim [LLNL; Weir, John [LLNL; Genoni, Thomas [VOSS; Toma, Carsten [VOSS

    2009-01-01

    The DARHT-II linear induction accelerator (LIA) now accelerates 2-kA electron beams to more than 17 MeV. This LIA is unique in that the accelerated current pulse width is greater than 2 microseconds. This pulse has a flat-top region where the final electron kinetic energy varies by less than 1% for more than 1.5 microseconds. The long risetime of the 6-cell injector current pulse is 0.5 {micro}s, which can be scraped off in a beam-head cleanup zone before entering the 68-cell main accelerator. We discuss our experience with tuning this novel accelerator; and present data for the resulting beam transport and dynamics. We also present beam stability data, and relate these to previous stability experiments at lower current and energy.

  5. Electron beam dynamics in the long-pulse, high-current DARHT-II linear induction accelerator

    International Nuclear Information System (INIS)

    The DARHT-II linear induction accelerator (LIA) now accelerates 2-kA electron beams to more than 17 MeV. This LIA is unique in that the accelerated current pulse width is greater than 2 microseconds. This pulse has a flat-top region where the final electron kinetic energy varies by less than 1% for more than 1.5 microseconds. The long risetime of the 6-cell injector current pulse is 0.5 (micro)s, which can be scraped off in a beam-head cleanup zone before entering the 68-cell main accelerator. We discuss our experience with tuning this novel accelerator; and present data for the resulting beam transport and dynamics. We also present beam stability data, and relate these to previous stability experiments at lower current and energy.

  6. Cathode performance during two beam operation of the high current high polarization electron gun for eRHIC

    International Nuclear Information System (INIS)

    Two electron beams from two activated bulk GaAs photocathodes were successfully combined during the recent beam test of the High Current High Polarization Electron gun for eRHIC. The beam test took place in Stangenes Industries in Palo Alto, CA, where the cathodes were placed in diagonally opposite locations inside the high voltage shroud. No significant cross talking between the cathodes was found for the pertinent vacuum and low average current operation, which is very promising towards combining multiple beams for higher average current. This paper describes the cathode preparation, transport and cathode performance in the gun for the combining test, including the QE and lifetimes of the photocathodes at various steps of the experiment.

  7. Electrostatic Matching of a High Current Proton Beam to a RFQ

    Energy Technology Data Exchange (ETDEWEB)

    Becker, R. [Scientific Software Service, Kapellenweg 2a, D-63571 Gelnhausen (Germany); Hamm, R. W. [R and M Technical Enterprises, 4725 Arlene Pl., Pleasanton CA 94566 (United States); Pearce-Percy, H. [CPAC, 6336B Patterson Pass Road, Livermore, CA 94550 (United States)

    2011-12-13

    In order to demonstrate the operation of a prototype DWA (dielectric wall accelerator), it was necessary to modify the LEBT of a commercially procured proton RFQ (Radio Frequency Quadrupole) injector linac. The relatively high output current (35 mA) of the duoplasmatron ion source at the low injection energy of 35 keV to the RFQ presented a matching problem in the beam transport due to the high space charge, the fixed transport length, and the small beam size required at the RFQ. In addition, only the use of electrostatic lenses was considered in order to minimize the size of the system. The standard AccSys design using one decel-accel einzel lens proved to be insufficient, so three new solutions were proposed, each using a pair of decelerating einzel lenses. The tool used to optimize these designs was a newly developed feature of the program IGUN. The RFQ acceptance ellipse is plotted on top of the phase space data of the transport calculation together with an ellipse with the same Twiss parameters which just encloses all the trajectories. The quality of matching is then given as the ratio of the areas of these two ellipses, making optimization easy. This paper will present the results of this optimization and the performance of the actual equipment built and tested.

  8. PRR1 rehabilitation and the current and future neutron beam utilization program

    International Nuclear Information System (INIS)

    The PRR1 research reactor is the center for nuclear science R and D in the Philippines. It is located in Metro Manila inside the campus of the University of the Philippines. It is a General Electric designed reactor and was commissioned in 1963 with a rated thermal power of 1 MW. It was operated for 20 years enabling the Institute to pursue activities in radioisotope production, neutron scattering, activation analyses and other R and D activities requiring neutron beams. In 1984 it was converted to a 3 MW TRIGA Type reactor. Conversion was completed and test run was successfully accomplished in 1988. In the same year the reactor was shut down due to a leak in the aluminum linear of the reactor pool. During the repair deterioration of the other parts of the reactor was discovered that could affect the safety of its operation. A rehabilitation program is made that include the reactor core box and all the other peripherals that could affect its safety operation and to address present regulatory concerns. Modification of the core box and its position in the pool opens opportunities and possibilities to suit specific neutron beam application for the users. Plans for this will be presented as well as the strategy of the Institute to satisfy the current need for reactor based facilities to enhanced implementation of the Country's S and T Program. (author)

  9. Surface treatment of 0.20% C carbon steel by high-current pulsed electron beam

    Institute of Scientific and Technical Information of China (English)

    XU Guo-cheng; FU Shi-you; GUAN Qing-feng

    2006-01-01

    A high-current pulsed electron beam(HCPEB) generated on the system of Nadezhda-2 was applied to improve the microstructure and performance of 0.20% C low carbon steel. Surface layers of the samples bombarded by explosive electron beam at different pulses was observed by using electron microscopy. The physical model of the thermal-stress process and related modification mechanism as a result of HCPEB irradiation was also investigated. After HCPEB post treatments, obvious changes in microstructure and significant hardening occur in the depth of 200-250 μm from the surface after HCPEB irradiation. Rapid heating and subsequent rapid solidification induce heavy plastic deformation, which results in that the laminated structure of pearlite is substituted by dispersive rounded-like cementites in the near-surface. The effect of HCPEB treatment can reach more than 500 m depth from the surface. The original crystalline structure is changed to a different degree that grows with the numbers of bombardment, and in the surface layer amorphous states and nanocrystaline structures consisting of grains of γ-phase and cementite are found. The violent stress induced by HCPEB irradiation is the origin of the nanostructured and amorphous structure formation.

  10. Effect of longitudinal applied magnetic field on the self-pinched critical current in intense electron beam diode

    Institute of Scientific and Technical Information of China (English)

    Liu Guo-Zhi; Huang Wen-Hua; Shao Hao; Xiao Ren-Zhen

    2006-01-01

    The effect of applied longitudinal magnetic field on the self-pinched critical current in the intense electron beam diode is discussed. The self-pinched critical current is derived and its validity is tested by numerical simulations. The results shows that an applied longitudinal magnetic field tends to increase the self-pinched critical current. Without the effect of anode plasma, the maximal diode current approximately equals the self-pinched critical current with the longitudinal magnetic field applied; when self-pinched occurs, the diode current approaches the self-pinched critical current.

  11. Study of non-inductive current drive using high energy neutral beam injection on JT-60U

    International Nuclear Information System (INIS)

    The negative ion based neutral beam (N-NB) current drive was experimentally studied. The N-NB driven current density was determined over a wide range of electron temperatures by using the motional Stark effect spectroscopy. Theoretical prediction of the NB current drive increasing with beam energy and electron temperature was validated. A record value of NB current drive efficiency 1.55 x 1019 Am-2W-1 was achieved simultaneously with high confinement and high beta at at a plasma current of 1.5 MA under a fully non-inductively current driven condition. The experimental validation of NB current drive theory for MHD quiescent plasmas gives greater confidence in predicting the NB current drive in future reactors. However, it was also found that MHD instabilities caused a degradation of NB current drive. A beam-driven instability expelled N-NB fast ions carrying non-inductive current from the central region. The lost N-NB driven current was estimated to be 7% of the total N-NB driven current. For the neoclassical tearing mode (NTM), comparisons of the measured neutron yield and fast ion pressure profile with transport code calculations revealed that the loss of fast ions increases with the NTM activity and that fast ions at higher energies suffer larger transport than at lower energies. (author)

  12. Current status of dental caries diagnosis using cone beam computed tomography

    International Nuclear Information System (INIS)

    The purpose of this article is to review the current status of dental caries diagnosis using cone beam computed tomography (CBCT). An online PubMed search was performed to identify studies on caries research using CBCT. Despite its usefulness, there were inherent limitations in the detection of caries lesions through conventional radiograph mainly due to the two-dimensional (2D) representation of caries lesions. Several efforts were made to investigate the three-dimensional (3D) image of lesion, only to gain little popularity. Recently, CBCT was introduced and has been used for diagnosis of caries in several reports. Some of them maintained the superiority of CBCT systems, however it is still under controversies. The CBCT systems are promising, however they should not be considered as a primary choice of caries diagnosis in everyday practice yet. Further studies under more standardized condition should be performed in the near future.

  13. Surface modification of mold steel SKD11 by high current pulsed electron beam

    International Nuclear Information System (INIS)

    Mechanism of surface modification technique by high current pulsed electron beam (HCPEB) was studied with SKD11 steel samples. It was found that crater-like defects would formed on the irradiated surface, the area density of craters and surface roughness decreased with the increasing number of HCPEB pulses. According to the XRD patterns, carbides in the modified surface layers dissolved after several HCPEB pulses and a high-percentage austenite microstructure is formed, but excessive energy deposition resulted in decomposition of the austenite. Treating the samples at 19.8 kV, the wear resistance of modified SKD11 steel improved and the greatest enhancement occurred at 8 pulses. Discussions were given on changes in contents of carbide and austenite in the surface layers. (authors)

  14. Practical Framework for an Electron Beam Induced Current Technique Based on a Numerical Optimization Approach

    Science.gov (United States)

    Yamaguchi, Hideshi; Soeda, Takeshi

    2015-03-01

    A practical framework for an electron beam induced current (EBIC) technique has been established for conductive materials based on a numerical optimization approach. Although the conventional EBIC technique is useful for evaluating the distributions of dopants or crystal defects in semiconductor transistors, issues related to the reproducibility and quantitative capability of measurements using this technique persist. For instance, it is difficult to acquire high-quality EBIC images throughout continuous tests due to variation in operator skill or test environment. Recently, due to the evaluation of EBIC equipment performance and the numerical optimization of equipment items, the constant acquisition of high contrast images has become possible, improving the reproducibility as well as yield regardless of operator skill or test environment. The technique proposed herein is even more sensitive and quantitative than scanning probe microscopy, an imaging technique that can possibly damage the sample. The new technique is expected to benefit the electrical evaluation of fragile or soft materials along with LSI materials.

  15. High current ion beam generation by nonlinear ponderomotive force of high intensity UV laser

    International Nuclear Information System (INIS)

    Using the anomaly at plasma interaction of petawatt-picosecond laser pulses with very high contrast ratio to generate plane geometry highly directed plasma blocks for laser fusion, the details of the block generation were studied. The aim was to produce plasma blocks with dielectrically generated highest possible initial thicknesses. One of the goals in laser-plasma interaction studies is to convert as much laser energy as possible into energetic particles. Most laser ion accelerations have only been done using infrared lasers. In this work, dependency of the laser energy absorption to laser wave-Length for a given laser intensity is investigated numerically. High intensity UV laser absorption by Raleigh plasma density is examined. High current ion beams generated by nonlinear ponderomotive force of intense UV laser with Hydrodynamics computation based on a genuine two-fluid code are presented. (author)

  16. Current status of dental caries diagnosis using cone beam computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Park, Young Seok; Ahn, Jin Soo; Kwon, Ho Beom; Lee, Seung Pyo [School of Dentistry, Seoul National University, Seoul (Korea, Republic of)

    2011-06-15

    The purpose of this article is to review the current status of dental caries diagnosis using cone beam computed tomography (CBCT). An online PubMed search was performed to identify studies on caries research using CBCT. Despite its usefulness, there were inherent limitations in the detection of caries lesions through conventional radiograph mainly due to the two-dimensional (2D) representation of caries lesions. Several efforts were made to investigate the three-dimensional (3D) image of lesion, only to gain little popularity. Recently, CBCT was introduced and has been used for diagnosis of caries in several reports. Some of them maintained the superiority of CBCT systems, however it is still under controversies. The CBCT systems are promising, however they should not be considered as a primary choice of caries diagnosis in everyday practice yet. Further studies under more standardized condition should be performed in the near future.

  17. Time Resolved Ion Beam Induced Current measurements on MOS capacitors using a cyclotron microbeam

    International Nuclear Information System (INIS)

    As overlayers on electronic devices become progressively thicker, radiation effects microscopy using traditional microbeams (with ion energies up to a few tens of MeVs) is becoming less and less viable. To penetrate to the sensitive regions of these devices, much higher energies, several hundreds of MeVs are necessary. These high energies are available only from cyclotrons. A nuclear microprobe has been developed on the AVF cyclotron of the Takasaki Ion Accelerators for Advanced Radiation Applications (TIARA) facility. In this paper we will present the first results using 260 MeV Ne and 520 MeV Ar microbeams to perform Time Resolved Ion Beam Induced Current (TRIBIC) measurements on Metal-Oxide-Semiconductor (MOS) capacitors. The results will be compared to data taken with a traditional 15 MeV O microbeam.

  18. High current pulsed electron beam modification on fretting wear behavior of D2 die steel

    International Nuclear Information System (INIS)

    The author studied the effect of high current pulsed electron beam (HCPEB) treatment on fretting wear ability of D2 die steel. It is shown that the most pronounced structural changes occur in the near-surface region, where the energy deposition is at its maximum. The fretting tests under dry condition were carried out on both treated and untreated specimens. The HCPEB treatment increases the fretting wear resistance significantly, and the improvement is further enhanced by surface pre-alloying by TiN and Cr. SEM analysis of the wear scars showed that the fretting wear mechanism of Cr coating is adhesive and oxidation wear, that of the TiN coating and non-coating D2 die steel is particle detachment through the propagation and fracture of fatigue microcracks on surface, and slight adhesive and oxidation wear is found, its wear mechanism is more complex

  19. Zeeman polarimetry measurement for edge current density determination using Li-beam probe on JT-60U

    International Nuclear Information System (INIS)

    Zeeman polarimetry system using Li-beam probe has been developed for the edge current density measurement in the JT-60U tokamak, which measures the polarization angle α (related to the pitch angle of the magnetic field) by means of photoelastic modulators, etalons, and phase sensitive detection using digital lock-in amplifiers with the accuracy in the α of Δα∼0.1 deg. The diagnostic has 20-channel viewing chords covering the plasma peripheral region of normalized minor radius r/a∼0.8-1 with a spatial resolution of up to ∼1 cm. Li-beam injection with beam current of up to ∼5 mA has been achieved. A new tuning method of the wavelength for the etalon has been demonstrated, scanning the beam acceleration voltage and keeping a beam current constant during a single shot. The peak wavelength of the etalon is adjusted in the direction to both blue- and redshifts by changing the angle of incidence and increasing the temperature, respectively. Time evolution of the edge current density profile has been determined for the current ramp experiment in the Ohmically heated discharges. In addition, the edge current density profile with the local peak of jped∼0.15-0.25 MA/m2 at r/a∼0.9 has been identified in the H-mode plasma, which is correlated with large pressure gradient in the pedestal region.

  20. Design and characterization of the annular cathode high current pulsed electron beam source for circular components

    Science.gov (United States)

    Jiang, Wei; Wang, Langping; Wang, Xiaofeng

    2016-08-01

    In order to irradiate circular components with high current pulsed electron beam (HCPEB), an annular cathode based on carbon fiber bunches was designed and fabricated. Using an acceleration voltage of 25 kV, the maximum pulsed irradiation current and energy of this annular cathode can reach 7.9 kA and 300 J, respectively. The irradiation current density distribution of the annular cathode HCPEB source measured along the circumferential direction shows that the annular cathode has good emission uniformity. In addition, four 9310 steel substrates fixed uniformly along the circumferential direction of a metal ring substrate were irradiated by this annular cathode HCPEB source. The surface and cross-section morphologies of the irradiated samples were characterized by scanning electron microscopy (SEM). SEM images of the surface reveal that crater and surface undulation have been formed, which hints that the irradiation energy of the HCPEB process is large enough for surface modification of 9310 steel. Meanwhile, SEM cross-section images exhibit that remelted layers with a thickness of about 5.4 μm have been obtained in all samples, which proves that a good practical irradiation uniformity can be achieved by this annular cathode HCPEB source.

  1. Stability of a current carrying single nanowire of tungsten (W) deposited by focused ion beam

    Science.gov (United States)

    Mandal, Pabitra; Das, Bipul; Raychaudhuri, A. K.

    2016-02-01

    We report an investigation on the stability of single W nanowire (NW) under direct current stressing. The NW of width ≈ 80 nm and thickness ≈ 100 nm was deposited on a SiO2/Si substrate by Focused Ion Beam (FIB) of Ga ions using W(CO)6 as a precursor. Such nanowires, used as interconnects in nanoelectronics, contain C and Ga in addition to W. The stability studies, done for the first time in such FIB deposited NWs, show that under current stressing these NWs behave very differently from that observed in conventional metal NWs or interconnects. The failure of such FIB deposited NW occurs at a relatively low current density (˜1011 A/m2) which is an order or more less than that seen in conventional metal NWs. The failure accompanies with formation of voids and hillocks, suggesting ionic migration as the cause of failure. However, the polarities of void and hillock formations are opposite to those observed in conventional metal interconnects. This observation along with preferential agglomeration of Ga ions in hillocks suggests that the ionic migration in such NWs is dominated by direct force as opposed to the migration driven by electron wind force in conventional metal interconnects.

  2. Degradation and decoloration of textiles wastewater by electron beam irradiation: Effect of energy, current and absorbed dose

    Energy Technology Data Exchange (ETDEWEB)

    Bakar, Khomsaton Abu; Zulkafli,; Hashim, Siti A' aisah [Malaysian Nuclear Agency (Nuclear Malaysia), Bangi 43000 Kajang Selangor (Malaysia); Ahmad, Pauzi [Universiti Kebangsaan Malaysia, 43600 UKM, Bangi Selangor (Malaysia)

    2014-09-03

    In this study, electron beam accelerator (EB) was used to treat textiles wastewater from Rawang Industrial Park, Selangor. The objectives were to determine effective energy, beam current and absorbed dose required for decoloration and degradation of the textiles effluent. The textiles effluent was irradiated in a batch with various energy of 1MeV to 3MeV at constant beam current of 30mA. It was observed that removal of color and COD increases with higher beam energy. The EB energy of 1MeV effectively to removed 58% color and 19% COD. For textile effluent sample irradiated at fix energy of 1MeV and 3Mev but at different beam current 10mA, 20mA and 30mA. It was observed that removal of color and COD increases with the increased of beam current at each energy. However removal of color was significantly better at 1Mev as compared to 3Mev. In the case of textiles effluent, irradiated at doses of 17, 20,25,30, 35, 100 and 200kGy using 30 kW power of EB (1Mev, 30mA), results shows removal of BOD{sub 5}, COD and color were in the range 9%-33%, 14%-38% and 43%-78% respectively.

  3. Degradation and decoloration of textiles wastewater by electron beam irradiation: Effect of energy, current and absorbed dose

    International Nuclear Information System (INIS)

    In this study, electron beam accelerator (EB) was used to treat textiles wastewater from Rawang Industrial Park, Selangor. The objectives were to determine effective energy, beam current and absorbed dose required for decoloration and degradation of the textiles effluent. The textiles effluent was irradiated in a batch with various energy of 1MeV to 3MeV at constant beam current of 30mA. It was observed that removal of color and COD increases with higher beam energy. The EB energy of 1MeV effectively to removed 58% color and 19% COD. For textile effluent sample irradiated at fix energy of 1MeV and 3Mev but at different beam current 10mA, 20mA and 30mA. It was observed that removal of color and COD increases with the increased of beam current at each energy. However removal of color was significantly better at 1Mev as compared to 3Mev. In the case of textiles effluent, irradiated at doses of 17, 20,25,30, 35, 100 and 200kGy using 30 kW power of EB (1Mev, 30mA), results shows removal of BOD5, COD and color were in the range 9%-33%, 14%-38% and 43%-78% respectively

  4. A high-current electron gun for the electron beam ion trap at the National Superconducting Cyclotron Laboratory

    Science.gov (United States)

    Schwarz, S.; Baumann, T. M.; Kittimanapun, K.; Lapierre, A.; Snyder, A.

    2014-02-01

    The Electron Beam Ion Trap (EBIT) in NSCL's reaccelerator ReA uses continuous ion injection and accumulation. In order to maximize capture efficiency and minimize breeding time into high charge states, the EBIT requires a high-current/high current-density electron beam. A new electron gun insert based on a concave Ba-dispenser cathode has been designed and built to increase the current transmitted through the EBIT's superconducting magnet. With the new insert, stable EBIT operating conditions with 0.8 A of electron beam have been established. The design of the electron gun is presented together with calculated and measured perveance data. In order to assess the experimental compression of the electron beam, a pinhole CCD camera has been set up to measure the electron beam radius. The camera observes X-rays emitted from highly charged ions, excited by the electron beam. Initial tests with this camera setup will be presented. They indicate that a current density of 640 A/cm2 has been reached when the EBIT magnet was operated at 4 T.

  5. A high-current electron gun for the electron beam ion trap at the National Superconducting Cyclotron Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, S., E-mail: schwarz@nscl.msu.edu; Baumann, T. M.; Kittimanapun, K.; Lapierre, A.; Snyder, A. [National Superconducting Cyclotron Laboratory (NSCL), Michigan State University, East Lansing, Michigan 48824 (United States)

    2014-02-15

    The Electron Beam Ion Trap (EBIT) in NSCL’s reaccelerator ReA uses continuous ion injection and accumulation. In order to maximize capture efficiency and minimize breeding time into high charge states, the EBIT requires a high-current/high current-density electron beam. A new electron gun insert based on a concave Ba-dispenser cathode has been designed and built to increase the current transmitted through the EBIT’s superconducting magnet. With the new insert, stable EBIT operating conditions with 0.8 A of electron beam have been established. The design of the electron gun is presented together with calculated and measured perveance data. In order to assess the experimental compression of the electron beam, a pinhole CCD camera has been set up to measure the electron beam radius. The camera observes X-rays emitted from highly charged ions, excited by the electron beam. Initial tests with this camera setup will be presented. They indicate that a current density of 640 A/cm{sup 2} has been reached when the EBIT magnet was operated at 4 T.

  6. Microstructures and properties of zirconium-702 irradiated by high current pulsed electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Shen [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Cai, Jie [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Engineering Institute of Advanced Manufacturing and Modern Equipment Technology, Jiangsu University, Zhenjiang 212013 (China); Lv, Peng; Zhang, Conglin; Huang, Wei [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Guan, Qingfeng, E-mail: guanqf@mail.ujs.edu.cn [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2015-09-01

    Highlights: • Zirconium-702 irradiated by high current pulsed electron beam was investigated. • Irradiated surface was melted and martensitic phase transformation occurred. • High density dislocations and deformation twins were formed in melted layer. • Micropores and ultrafine structures were also obtained on the irradiated surface. • Microhardness and corrosion resistance were improved after HCPEB irradiation. - Abstract: The microstructure, hardness and corrosion resistance of zirconium-702 before and after high-current pulsed electron beam (HCPEB) irradiation have been investigated. The microstructure evolution and surface morphologies of the samples were characterized by using X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The experimental results indicate that the sample surface was melted after HCPEB irradiation, and martensitic phase transformation occurred. Besides, two kinds of craters as well as ultrafine structures were obtained in the melted layer. TEM observations suggest that high density dislocations and deformation twins were formed after HCPEB irradiation. With the increasing of pulses, microhardness of the irradiated samples was increased from the initial 178 Hv to 254 Hv. The corrosion resistance was tested by using electrode impedance spectroscopy (EIS) and potentiodynamic polarization curves. Electrochemical results show that, after HCPEB irradiation, all the samples had better corrosion resistance in 1 mol HNO{sub 3} solution compared to the initial one, among which the 5-pulsed sample owned the best corrosion resistance. Ultrafine structures, martensitic phase transformation, surface porosities, dislocations and deformation twins are believed to be the dominant reasons for the improvement of the hardness and corrosion resistance.

  7. A particle-core-MD model for intrabeam scattering and halo formation in high current beams in a FODO channel

    CERN Document Server

    Uhlmann, N; Comunian, M; Pisent, A

    2002-01-01

    An essential problem for the successful operation of high current linear ion accelerators is the control of beam losses due to halo particles. As a possible mechanism for the formation of such a halo we concentrate on the interplay between intrabeam scattering (IBS) and the incidence of particles which are driven to high amplitudes by resonances with the nonlinear space charge fields of a mismatched beam. Since a fully microscopic numerical treatment including all the mutual Coulomb interactions between the beam ions requires much too high computational effort, we developed an approximative method. These particle-core-molecular-dynamics (PCMD) simulations suitably join the mean-field description of the time evolution of the beam in framework of the envelope equations and a microscopic calculation of the Coulomb interactions between pseudo-particles with a renormalized charge. With this method we studied matched and mismatched continuous KV-beams in a FODO channel. In first simulation runs we observed a signif...

  8. Ion beams and material science facilities using high current low energy 3.0 MV particle accelerator at NCAR, Bilaspur

    International Nuclear Information System (INIS)

    The national facility for interdisciplinary research using ion beams based on 3.0 MV Pelletron accelerator (9SDH, NEC) with high current TORVIS (for H, He ions) and SNICS (for heavy ions) sources, and two beam lines for ion beam analysis (IBA) and ion implantation/irradiation have been successfully commissioned at NCAR, Department of Pure and Applied Physics, Guru Ghasidas Vishwavidyalaya, Bilaspur. The accelerator conditioning was done over a period of time to achieve desired level of terminal voltage and vacuum in the accelerator tank, 3.0 MV terminal voltage was achieved with chain currents 120 A and an applied charging voltage of 13 kV. The vacuum without beam acceleration was lower 10-8 torr on both sides of the Pelletron tank. Finally, the first beam demonstration was achieved when a proton beam accelerated with terminal potential of 0.965 MV was seen at the Au target in Ion Beam analysis (IBA) chamber, the energy at the Faraday cup (FC) just before the chamber was 0.5 eA. Details of the facilities tested and the results obtained so far will be discussed in the paper

  9. Experimental research of different plasma cathodes for generation of high-current electron beams

    International Nuclear Information System (INIS)

    The results of experimental studies of different types of cathodes—carbon-epoxy rods, carbon-epoxy capillary, edged graphite, and metal-dielectric—under the application of high-voltage pulses with an amplitude of several hundreds of kV and pulse duration of several nanoseconds are presented. The best diode performance was achieved with the edged graphite and carbon-epoxy-based cathodes characterized by uniform and fast (<1 ns) formation of explosive emission plasma spots and quasi-constant diode impedance. This result was achieved for both annular cathodes in a strong magnetic field and planar cathodes of a similar diameter (∼2 cm) with no external magnetic field. The cathodes based on carbon-epoxy rods and carbon-epoxy capillaries operating with an average current density up to 1 kA/cm2 showed insignificant erosion along 106 pulses of the generator and the generated electron beam current showed excellent reproducibility in terms of the amplitude and waveform

  10. Experimental research of different plasma cathodes for generation of high-current electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Shafir, G.; Kreif, M.; Gleizer, J. Z.; Gleizer, S.; Krasik, Ya. E. [Physics Department, Technion, Haifa 32000 (Israel); Gunin, A. V.; Kutenkov, O. P.; Rostov, V. V. [Institute of High Current Electronics, Siberian Branch, Russian Academy of Sciences, Tomsk 634055 (Russian Federation); Pegel, I. V. [Institute of High Current Electronics, Siberian Branch, Russian Academy of Sciences, Tomsk 634055 (Russian Federation); Tomsk Polytechnic University, Tomsk 634034 (Russian Federation)

    2015-11-21

    The results of experimental studies of different types of cathodes—carbon-epoxy rods, carbon-epoxy capillary, edged graphite, and metal-dielectric—under the application of high-voltage pulses with an amplitude of several hundreds of kV and pulse duration of several nanoseconds are presented. The best diode performance was achieved with the edged graphite and carbon-epoxy-based cathodes characterized by uniform and fast (<1 ns) formation of explosive emission plasma spots and quasi-constant diode impedance. This result was achieved for both annular cathodes in a strong magnetic field and planar cathodes of a similar diameter (∼2 cm) with no external magnetic field. The cathodes based on carbon-epoxy rods and carbon-epoxy capillaries operating with an average current density up to 1 kA/cm{sup 2} showed insignificant erosion along 10{sup 6} pulses of the generator and the generated electron beam current showed excellent reproducibility in terms of the amplitude and waveform.

  11. Structure and properties of combined protective coatings with use high-current electron beam irradiation

    International Nuclear Information System (INIS)

    Full text: Improvement of superficial materials and products is the important task. The high-efficiency vacuum - arc sources created recently open more ample opportunities for change of properties of a surface of metal materials. Now there is a number of known technologies on drawing coverings for updating a surface of working parts of metals. Today the protecting coatings, which were deposited on tools applied in electrochemical and chemical devices, acquired a great interest. It is known that some kinds of treatment, such as, for example, ion implantation, ion-assisted deposition of thin films, electron beam irradiation, CVD, PVD, etc. cannot result directly in desired effect. Therefore to resolve some application problems, one has to use combined methods of treatment, which allow one to resolve complicated serious problems of material science and industrial fields, for example, in space, automobile, aviation, ship building, etc. So, the goal of this work was to study the structure, element composition and properties of hybrid coatings on TiNi/Cr/Al2O3 and TiN/Al2O3 base, which were deposited on AISI 321 stainless steel before and after electron beam irradiation. A special attention was paid to studies of diffusion and mass-transfer processes. We applied XRD, RBS, AES, SEM with micro-analysis as well as corrosion in sulfur acid, adhesion and hardness tests. It had been demonstrated that these coatings were able to perform different functions as protecting coatings. Tests of TiN/Al2O3 and TiN/Cr/Al2O3 coatings, which were deposited on AISI 321 steel, after high-current electron beam irradiation demonstrated significant increase in corrosion resistance in H2SO4 solution under 4000C temperature. Hardness and adhesion of these coatings to substrate increased, and significant decrease in friction wear of coating surfaces was found. In such a way, in this report it was demonstrated that hybrid coatings on TiN/Cr/Al2O3 and TiN/Al2O3 base after HCEB irradiation under

  12. Production of high current proton beams using complex H-rich molecules at GSI

    Science.gov (United States)

    Adonin, A.; Barth, W.; Heymach, F.; Hollinger, R.; Vormann, H.; Yakushev, A.

    2016-02-01

    In this contribution, the concept of production of intense proton beams using molecular heavy ion beams from an ion source is described, as well as the indisputable advantages of this technique for operation of the GSI linear accelerator. The results of experimental investigations, including mass-spectra analysis and beam emittance measurements, with different ion beams (CH3+,C2H4+,C3H7+) using various gaseous and liquid substances (methane, ethane, propane, isobutane, and iodoethane) at the ion source are summarized. Further steps to improve the ion source and injector performance with molecular beams are depicted.

  13. Production of high current proton beams using complex H-rich molecules at GSI

    Energy Technology Data Exchange (ETDEWEB)

    Adonin, A., E-mail: a.adonin@gsi.de; Barth, W.; Heymach, F.; Hollinger, R.; Vormann, H.; Yakushev, A. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt 64291 (Germany)

    2016-02-15

    In this contribution, the concept of production of intense proton beams using molecular heavy ion beams from an ion source is described, as well as the indisputable advantages of this technique for operation of the GSI linear accelerator. The results of experimental investigations, including mass-spectra analysis and beam emittance measurements, with different ion beams (CH{sub 3}{sup +},C{sub 2}H{sub 4}{sup +},C{sub 3}H{sub 7}{sup +}) using various gaseous and liquid substances (methane, ethane, propane, isobutane, and iodoethane) at the ion source are summarized. Further steps to improve the ion source and injector performance with molecular beams are depicted.

  14. Crane RF accelerator for high current radiation damage studies

    International Nuclear Information System (INIS)

    An electron accelerator was designed and built for the Naval Weapons Support Center for transient radiation effects on electronics experiments and testing. The Crane L Band RF Electron Linac was designed to provide high currents over a wide range of pulse widths and energies. The energy extends to 60 MeV and pulse widths vary from a few ns to 10 μsec. Beam currents range from 20 amps in the short pulse case to 1.5 amps in the long pulse case. This paper describes the linac, its architecture, the e-gun and pulser, waveguides, klystrons and modulator, vacuum system, beam transport, and control systems. fig., tab

  15. Dynamics of a relativistic electron beam in a high-current diode with a knife-edge cathode

    International Nuclear Information System (INIS)

    For a number of practical applications, e.g., producing discharges in large volumes in order to pump gas lasers and for short x-ray pulses, it is necessary to generate electron beams in megamp range with electron energies from hundreds of kilovolts to several megavolts. It has been possible to obtain high currents (I ± 1 MA) by using diodes with knife-edge cathodes. Knife-edge diodes have an important advantage over the parapotential type because the ion current in them comprises a relatively small fraction of the total current. This is because the electron path in the accelerating gap of knife-edge diodes is quite short in comparison with that in high-current parapotential diodes. From the point of view of applying ribbon-shaped or narrow electron beams, the important problems are in measuring the current-voltage characteristics of the diodes and determining the dynamics of the energy spectrum and the angular spread of the electrons. The generation of an electron beam with a current ∼130 kA and pulse length ∼60 ns is studied. The current-voltage characteristics of knife-edge diodes with various geometries, the dynamics of the angular spread, and the beam structure are studied. As a result of the study of the REB dynamics it is found that the operation of the diode with these experiments can be approximated by a proposed formula which includes the finite thickness of the knife-edge cathode and the motion of the plasma and ions in the discharge gap. Breaking up of the beam into individual current-carrying channels is observed with the characteristic scale ∼1-2 mm. It is noted that for the diode geometry with a knife-edge cathode, when the magnetic field changes sign and passes through zero, an instability can exist which is analogous to the dissipative tearing instability

  16. Generation of a 500-keV electron beam with milliampere current from a photoemission DC gun

    International Nuclear Information System (INIS)

    A high-brightness, high-current electron gun for energy recovery linac light sources and high repetition rate X-ray FEL requires an exit beam energy of ≥ 500 keV to reduce space-charge induced emittance growth in the drift space from the gun exit to the following accelerator entrance. We have developed a DC photoemission gun employing a segmented insulator to mitigate the field emission problem, which is a major obstacle for operation of DC guns at ≥ 500 kV. The first demonstration of generating a 500-keV electron beam with currents up to 1.8 mA is presented. (author)

  17. Commissioning results of the Amsterdam Pulse Stretcher/Storage ring AmPS

    International Nuclear Information System (INIS)

    AmPS has been built to enhance substantially the main specifications of the 1 % duty factor 550 MeV electron accelerator facility MEA. The maximum energy will be raised to 0.9 GeV while the duty factor increases from 1 % to approximately 100 %. To this purpose the ring AmPS was added to the facility. Simultaneously the linac was upgraded both in current and energy. Two modes of operation for the ring are implemented: a Pulse Stretcher mode with 3 turn injection creating an external beam, and a Storage Mode with multi turn injection for internal target physics. The commissioning of the ring started in April 1992. Within two months 10 % duty factor beams could be delivered for electron scattering experiments. Meanwhile the performance of the machine has been improved dramatically. The actual performance of the ring is presented and is compared with the initial design goals

  18. High energy, high current neutral beam injector operation with single stage and two-stage multi-aperture extraction systems

    International Nuclear Information System (INIS)

    Neutral beam development for JET injectors at FAR laboratory has led to the study of properties of a single stage (triode) and a two-stage (tetrode) multi-aperture extraction system at ion beam powers exceeding the megawatt level and up to 80 keV beam energy. The results of the experimental measurements and of a numerical study of the beam optical qualities and grid power loadings of these systems are presented. Grid power loading levels of less than 1% of the high-voltage drain power were measured in both the triode and the tetrode accelerators. This would allow long pulse operation (10 s with water-cooling) as required for JET. The beam divergence angle (α approx.= 0.70) and the transmission characteristics were almost identical. At the same energy, higher current densities, at optimum perveance, were obtained with the triode at a lower electric field stress on the high-voltage gap. The triode offers the additional advantage of being simpler from the mechanical and electrical points of view. Operation of the injection line with an electrostatic beam dump associated with a grounded source is also demonstrated for a 25 A ion beam up to 60 keV. (orig.)

  19. High energy, high current neutral beam injector operation with single stage and two-stage multi-aperture extraction systems

    Science.gov (United States)

    Becherer, R.; Desmons, M.; Fumelli, M.; Raimbault, P.; Valckx, F. P. G.

    1982-12-01

    Neutral beam development for JET injections at FAR laboratory has led to the study of properties of a single stage (triode) and a two-stage (tetrode) multi-aperture extraction system at ion beam powers exceeding the megawatt level and up to 80 keV beam energy. The results of the experimental measurements and of a numerical study of the beam optical qualities and grid power loadings of these systems are presented. Grid power loading levels of less than 1% of the high-voltage drain power were measured in both the triode and the tetrode accelerators. This would allow long pulse operation (10 s with water-cooling) as required for JET. The beam divergence angle (α ≅ 0.7°) and the transmission characteristics were almostidentical. At the same energy, higher current densities, at optimum perveance, were obtained with the triode at a lower electric field stress on the high-voltage gap. The triode offers the additional advantage of being simpler from the mechanical and electrical points of view. Operation of the injection line with an electrostatic beam dump associated with a grounded source is also demonstrated for a 25 ion beam up to 60 keV.

  20. Study on Nanostructures Induced by High-Current Pulsed Electron Beam

    Directory of Open Access Journals (Sweden)

    Bo Gao

    2012-01-01

    Full Text Available Four techniques using high-current pulsed electron beam (HCPEB were proposed to obtain surface nanostructure of metal and alloys. The first method involves the distribution of several fine Mg nanoparticles on the top surface of treated samples by evaporation of pure Mg with low boiling point. The second technique uses superfast heating, melting, and cooling induced by HCPEB irradiation to refine the primary phase or the second phase in alloys to nanosized uniform distributed phases in the matrix, such as the quasicrystal phase Mg30Zn60Y10 in the quasicrystal alloy Mg67Zn30Y3. The third technique involves the refinement of eutectic silicon phase in hypereutectic Al-15Si alloys to fine particles with the size of several nanometers through solid solution and precipitation refinement. Finally, in the deformation zone induced by HCPEB irradiation, the grain size can be refined to several hundred nanometers, such as the grain size of the hypereutectic Al-15Si alloys in the deformation zone, which can reach ~400 nm after HCPEB treatment for 25 pulses. Therefore, HCPEB technology is an efficient way to obtain surface nanostructure.

  1. Microstructures and properties of zirconium-702 irradiated by high current pulsed electron beam

    Science.gov (United States)

    Yang, Shen; Cai, Jie; Lv, Peng; Zhang, Conglin; Huang, Wei; Guan, Qingfeng

    2015-09-01

    The microstructure, hardness and corrosion resistance of zirconium-702 before and after high-current pulsed electron beam (HCPEB) irradiation have been investigated. The microstructure evolution and surface morphologies of the samples were characterized by using X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The experimental results indicate that the sample surface was melted after HCPEB irradiation, and martensitic phase transformation occurred. Besides, two kinds of craters as well as ultrafine structures were obtained in the melted layer. TEM observations suggest that high density dislocations and deformation twins were formed after HCPEB irradiation. With the increasing of pulses, microhardness of the irradiated samples was increased from the initial 178 Hv to 254 Hv. The corrosion resistance was tested by using electrode impedance spectroscopy (EIS) and potentiodynamic polarization curves. Electrochemical results show that, after HCPEB irradiation, all the samples had better corrosion resistance in 1 mol HNO3 solution compared to the initial one, among which the 5-pulsed sample owned the best corrosion resistance. Ultrafine structures, martensitic phase transformation, surface porosities, dislocations and deformation twins are believed to be the dominant reasons for the improvement of the hardness and corrosion resistance.

  2. Radiation response of multi-quantum well solar cells: Electron-beam-induced current analysis

    Energy Technology Data Exchange (ETDEWEB)

    Maximenko, S. I., E-mail: sergey.maximenko@nrl.navy.mil; Scheiman, D. A.; Jenkins, P. P.; Walters, R. J. [Naval Research Laboratory, Washington, DC 20375 (United States); Lumb, M. P.; Hoheisel, R. [The George Washington University, Washington, DC 20052 (United States); Gonzalez, M. [Sotera Defense Solutions, Herndon, Virginia 20171 (United States); Messenger, S. R. [University of Maryland Baltimore County, Baltimore, Maryland 21250 (United States); Tibbits, T. N. D. [QuantaSol Ltd, Kingston-upon-Thames KT1 3GZ (United Kingdom); Imaizumi, M. [Japan Aerospace Exploration Agency (JAXA), Tsukuba, Ibaraki 305-8505 (Japan); Ohshima, T.; Sato, S. I. [Japan Atomic Energy Agency (JAEA), Takasaki, Gunma 370-1292 (Japan)

    2015-12-28

    Solar cells utilizing multi-quantum well (MQW) structures are considered promising candidate materials for space applications. An open question is how well these structures can resist the impact of particle irradiation. The aim of this work is to provide feedback about the radiation response of In{sub 0.01}Ga{sub 0.99}As solar cells grown on Ge with MQWs incorporated within the i-region of the device. In particular, the local electronic transport properties of the MQW i-regions of solar cells subjected to electron and proton irradiation were evaluated experimentally using the electron beam induced current (EBIC) technique. The change in carrier collection distribution across the MQW i-region was analyzed using a 2D EBIC diffusion model in conjunction with numerical modeling of the electrical field distribution. Both experimental and simulated findings show carrier removal and type conversion from n- to p-type in MQW i-region at a displacement damage dose as low as ∼6.06–9.88 × 10{sup 9} MeV/g. This leads to a redistribution of the electric field and significant degradation in charge carrier collection.

  3. Surface Modification of Light Alloys by Low-Energy High-Current Pulsed Electron Beam

    Directory of Open Access Journals (Sweden)

    X. D. Zhang

    2012-01-01

    Full Text Available This paper reviews results obtained by the research groups developing the low-energy high-current pulsed electron beam (LEHCPEB in Dalian (China and Metz (France on the surface treatment of light alloys. The pulsed electron irradiation induces an ultra-fast thermal cycle at the surface combined with the formation of thermal stress and shock waves. As illustrated for Mg alloys and Ti, this results in deep subsurface hardening (over several 100 μm which improves the wear resistance. The analysis of the top surface melted surface of light alloys also often witnesses evaporation and condensation of chemical species. This phenomenon can significantly modify the melt chemistry and was also suggested to lead to the development of specific solidification textures in the rapidly solidified layer. The potential use of the LEHCPEB technique for producing thermomechanical treatments under the so-called heating mode and, thus, modify the surface crystallographic texture, and enhance solid-state diffusion is also demonstrated in the case of the FeAl intermetallic compound.

  4. Ion beam annealing during high current density implants of phosphorus into silicon

    Energy Technology Data Exchange (ETDEWEB)

    Cannavo, S.; La Ferla, A.; Rimini, E.; Ferla, G.; Gandolfi, L.

    1986-06-15

    The damage left by high current densityapprox.10 ..mu..A/cm/sup 2/ implants of 120-keV P/sup +/ into 4-in. (500-..mu..m-thick) and 5-in. (600-..mu..m-thick) Si wafers of <100> orientation has been measured by 2.0-MeV He backscattering in combination with the channeling effect technique. The fluences ranged between 1 and 7.5 x 10/sup 15//cm/sup 2/. The amount of disorder is highest at 1 x 10/sup 15//cm/sup 2/ and then decreases with fluence. The annealing of the amorphous layer takes place by the movement of two and one amorphous--single crystal interfaces for the 500- and 600-..mu..m-thick wafers, respectively. The experimental data are compared with a beam annealing model based on the temperature-rise profile, the amount of point defects generated by the ion in the collision cascade volume, and the assumption of a regrowth process governed by an activation energy of 0.25 eV.

  5. Ion beam annealing during high current density implants of phosphorus into silicon

    International Nuclear Information System (INIS)

    The damage left by high current densityapprox.10 μA/cm2 implants of 120-keV P+ into 4-in. (500-μm-thick) and 5-in. (600-μm-thick) Si wafers of orientation has been measured by 2.0-MeV He backscattering in combination with the channeling effect technique. The fluences ranged between 1 and 7.5 x 1015/cm2. The amount of disorder is highest at 1 x 1015/cm2 and then decreases with fluence. The annealing of the amorphous layer takes place by the movement of two and one amorphous--single crystal interfaces for the 500- and 600-μm-thick wafers, respectively. The experimental data are compared with a beam annealing model based on the temperature-rise profile, the amount of point defects generated by the ion in the collision cascade volume, and the assumption of a regrowth process governed by an activation energy of 0.25 eV

  6. Ion beam annealing during high current density implants of phosphorus into silicon

    Science.gov (United States)

    Cannavó, S.; La Ferla, A.; Rimini, E.; Ferla, G.; Gandolfi, L.

    1986-06-01

    The damage left by high current density˜10 μA/cm2 implants of 120-keV P+ into 4-in. (500-μm-thick) and 5-in. (600-μm-thick) Si wafers of orientation has been measured by 2.0-MeV He backscattering in combination with the channeling effect technique. The fluences ranged between 1 and 7.5×1015/cm2. The amount of disorder is highest at 1×1015/cm2 and then decreases with fluence. The annealing of the amorphous layer takes place by the movement of two and one amorphous-single crystal interfaces for the 500- and 600-μm-thick wafers, respectively. The experimental data are compared with a beam annealing model based on the temperature-rise profile, the amount of point defects generated by the ion in the collision cascade volume, and the assumption of a regrowth process governed by an activation energy of 0.25 eV.

  7. Energetic high current density electron/ion beam generation in plasma opening switches

    International Nuclear Information System (INIS)

    Experimental results on the generation of high energy ion/electron beams during operation of microsecond/nanosecond Plasma Opening Switch (POS) are presented. For the nanosecond POS, a coaxial configuration with negatively charged central electrode was used. For the microsecond POS, a strip-line geometry was investigated. Different arrays of magnetically insulated Collimated Faraday Cups (CFC) were used to observe energetic electron/ion flows towards the anode/cathode POS electrodes and towards the load. It was shown that in both nanosecond and microsecond cases, high-energy high current density axial ion flows are generated downstream towards the load at the load side edge of the plasma. The main axial ion acceleration occurs in the first few cm downstream with respect to the load side edge of the plasma at the beginning of the POS opening. Data observed by the anode CFC array show fast axial propagation of a radial electron flow along the anode electrode towards the load which is accompanied by an ion flow that first appears at the generator side of the plasma. (author). 10 figs., 10 refs

  8. Radiation response of multi-quantum well solar cells: Electron-beam-induced current analysis

    International Nuclear Information System (INIS)

    Solar cells utilizing multi-quantum well (MQW) structures are considered promising candidate materials for space applications. An open question is how well these structures can resist the impact of particle irradiation. The aim of this work is to provide feedback about the radiation response of In0.01Ga0.99As solar cells grown on Ge with MQWs incorporated within the i-region of the device. In particular, the local electronic transport properties of the MQW i-regions of solar cells subjected to electron and proton irradiation were evaluated experimentally using the electron beam induced current (EBIC) technique. The change in carrier collection distribution across the MQW i-region was analyzed using a 2D EBIC diffusion model in conjunction with numerical modeling of the electrical field distribution. Both experimental and simulated findings show carrier removal and type conversion from n- to p-type in MQW i-region at a displacement damage dose as low as ∼6.06–9.88 × 109 MeV/g. This leads to a redistribution of the electric field and significant degradation in charge carrier collection

  9. Improved wear resistance of Al-15Si alloy with a high current pulsed electron beam treatment

    Science.gov (United States)

    Hao, Y.; Gao, B.; Tu, G. F.; Li, S. W.; Dong, C.; Zhang, Z. G.

    2011-07-01

    A hypereutectic Al-15Si alloy (Si 15 wt.%, Al balance) was irradiated by high current pulsed electron beam (HCPEB). The HCPEB treatment causes ultra-rapid heating, melting and cooling at the top surface layer. As a result, the special "halo" microstructure centering on the primary Si phase is formed on the surface due to interdiffusion of Al and Si elements. The composition of the "halo" microstructure is distributed continuously from the center to the edge of the "halo". Compared to an untreated matrix, the remelted layer underneath the surface presents single contrast because of the compositional homogeneity after HCPEB treatment. The thickness of the remelted layer increases slightly from 4.4 μm (5 pulses) to 5.6 μm (25 pulses). HCPEB treatment broadens and shifts the diffraction peaks of Al and Si. The lattice parameters of Al decreases due to the formation of a supersaturated solid solution of Al in the melted layer. Through analysis of Raman spectra and transmission electron microscopy (TEM), the amorphous Si (a-Si) and nanocrystalline Si are formed in the near-surface region under multiple bombardments of HCPEB. The relative wear resistance of a 15-pulse sample is effectively improved by a factor of 9, which can be attributed to the formation of metastable structures.

  10. Study on the effect of welding current during laser beam-resistance seam welding of aluminum alloy 5052

    Institute of Scientific and Technical Information of China (English)

    Li Yongqiang; Zhao Xihua; Zhao He; Cao Haipeng; Zhao Huanling

    2008-01-01

    The effect of welding current on the weld shape and tensile shear load during laser beam-resistance seam welding (LB-RSW) of aluminum alloy 5052 is studied. Experimental results show that the penetration depth, weld width,tensile shear load and the ratio of penetration depth to weld width of LB-RSW are bigger than those of laser beam welding(LBW) under the same conditions and the former three parameters increase as welding current rises. The weld shape of LB-RSW below 5 kA welding current is nearly the same as that of LBW. The weld morphology is protuberant under the condition of 5 kA welding current and 0.8 m/min welding speed. Furthermore, the microstructure of the weld seam of LB-RSW is coarser than that of LBW.

  11. Measurement of neutral current coherent neutral pion production on carbon in a few-GeV neutrino beam

    OpenAIRE

    Kurimoto, Y; Alcaraz-Aunion, J. L.; Brice, S J; Bugel, L.; Catala-Perez, J.; Cheng, G.; Conrad, J.M.; Djurcic, Z.; Dore, U.; Finley, D. A.; Franke, A. J.; C. Giganti; Gomez-Cadenas, J. J.; Guzowski, P.; Hanson, A.

    2010-01-01

    The SciBooNE Collaboration reports a measurement of neutral current coherent neutral pion production on carbon by a muon neutrino beam with average energy 0.8 GeV. The separation of coherent from inclusive neutral pion production has been improved by detecting recoil protons from resonant neutral pion production. We measure the ratio of the neutral current coherent neutral pion production to total charged current cross sections to be (1.16 +/- 0.24) x 10-2. The ratio of charged current cohere...

  12. Effect of external magnetic field on critical current for the onset of virtual cathode oscillations in relativistic electron beams

    Science.gov (United States)

    Hramov, Alexander; Koronovskii, Alexey; Morozov, Mikhail; Mushtakov, Alexander

    2008-02-01

    In this Letter we research the space charge limiting current value at which the oscillating virtual cathode is formed in the relativistic electron beam as a function of the external magnetic field guiding the beam electrons. It is shown that the space charge limiting (critical) current decreases with growth of the external magnetic field, and that there is an optimal induction value of the magnetic field at which the critical current for the onset of virtual cathode oscillations in the electron beam is minimum. For the strong external magnetic field the space charge limiting current corresponds to the analytical relation derived under the assumption that the motion of the electron beam is one-dimensional [D.J. Sullivan, J.E. Walsh, E. Coutsias, in: V.L. Granatstein, I. Alexeff (Eds.), Virtual Cathode Oscillator (Vircator) Theory, in: High Power Microwave Sources, vol. 13, Artech House Microwave Library, 1987, Chapter 13]. Such behavior is explained by the characteristic features of the dynamics of electron space charge in the longitudinal and radial directions in the drift space at the different external magnetic fields.

  13. Effect of external magnetic field on critical current for the onset of virtual cathode oscillations in relativistic electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Hramov, Alexander [Faculty of Nonlinear Processes, Saratov State University, Astrakhanskaya 83, Saratov 410012 (Russian Federation)], E-mail: aeh@nonlin.sgu.ru; Koronovskii, Alexey; Morozov, Mikhail; Mushtakov, Alexander [Faculty of Nonlinear Processes, Saratov State University, Astrakhanskaya 83, Saratov 410012 (Russian Federation)

    2008-02-04

    In this Letter we research the space charge limiting current value at which the oscillating virtual cathode is formed in the relativistic electron beam as a function of the external magnetic field guiding the beam electrons. It is shown that the space charge limiting (critical) current decreases with growth of the external magnetic field, and that there is an optimal induction value of the magnetic field at which the critical current for the onset of virtual cathode oscillations in the electron beam is minimum. For the strong external magnetic field the space charge limiting current corresponds to the analytical relation derived under the assumption that the motion of the electron beam is one-dimensional [D.J. Sullivan, J.E. Walsh, E. Coutsias, in: V.L. Granatstein, I. Alexeff (Eds.), Virtual Cathode Oscillator (Vircator) Theory, in: High Power Microwave Sources, vol. 13, Artech House Microwave Library, 1987, Chapter 13]. Such behavior is explained by the characteristic features of the dynamics of electron space charge in the longitudinal and radial directions in the drift space at the different external magnetic fields.

  14. Return current 2D-mapping of short-pulse relativistic electron beams propagating in gases

    International Nuclear Information System (INIS)

    A simple model for examining the effect of rotation on electron beam ''Hose'' instabilities is presented. Using a rigid beam approximation, it is found that the equilibrium rotation of an electron beam will couple to unstable displacements. The coupling arises from a -Y x ω /sub R/ term appearing in the force equation where Y is the displacement vector and ω /sub R/ is the rotation frequency of the beam. This term can be found from either single particle motion or cold-fluid hydro equations. The effect on hose instabilities is similar to a parallel B field and is stabilizing. In the case of real W, growth in z is reduced by 18% from the non-rotating beam case, for ω /sub R/ = ω /sub lb/ where ω /sub lb/ is the betatron frequency (the rotation frequency in the cold beam limit). Using the spread mass model of Ed Lee, finite growth rates are found for growth in /tau/ = z/c - t for real Ω = ω - kc, with most unstable modes occurring at -.61 ω /sub lb/ and 1.61 ω /sub lb/ for a cold beam. For a rotating annular beam, peak growth at - and 2.5 is seen in agreement with simulations. Comparison with experimental results is shown

  15. Proposed use of the radio-frequency quadrupole structure to funnel high-current ion beams

    International Nuclear Information System (INIS)

    In this paper, we describe a new approach to funneling beams that are initially accelerated in two radio-frequency quadrupole (RFQ) accelerators. Instead of discrete optical elements, we propose to funnel within an RFQ structure, so that during the funneling process the beam is always confined by periodic transverse focusing. Beams with high space charge experience irreversible emittance growth when they emerge from a periodic focusing system. To alleviate this problem, in the proposed funneling system it should be possible to maintain the same focusing periodicity as that of the accelerators preceding the funnel. Also, instead of conventional deflection systems, we propose to use the properties of a modified RFQ structure to deflect two parallel beams toward each other and to merge them into a single final beam. 1 ref., 3 figs

  16. Didactical formulation of the Ampère law

    International Nuclear Information System (INIS)

    The Ampère law is useful to calculate the magnetostatic field in the cases of distributions of current with high degree of symmetry. Nevertheless the magnetic field produced by a thin straight wire carrying a current I requires the Biot–Savart law and the use of the Ampère law leads to a mistake. A didactical formulation of the Ampère law is proposed to prevent misinterpretations. (letters and comments)

  17. Didactical formulation of the Ampère law

    Science.gov (United States)

    Barchiesi, Dominique

    2014-05-01

    The Ampère law is useful to calculate the magnetostatic field in the cases of distributions of current with high degree of symmetry. Nevertheless the magnetic field produced by a thin straight wire carrying a current I requires the Biot-Savart law and the use of the Ampère law leads to a mistake. A didactical formulation of the Ampère law is proposed to prevent misinterpretations.

  18. Transportation of high-current ion and electron beams in the accelerator drift gap in the presence of an additional electron background

    Energy Technology Data Exchange (ETDEWEB)

    Karas’, V. I., E-mail: karas@kipt.kharkov.ua; Kornilov, E. A.; Manuilenko, O. V. [National Academy of Sciences of Ukraine, National Science Center Kharkiv Institute of Physics and Technology (Ukraine); Tarakanov, V. P. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation); Fedorovskaya, O. V. [National Academy of Sciences of Ukraine, National Science Center Kharkiv Institute of Physics and Technology (Ukraine)

    2015-12-15

    The dynamics of a high-current ion beam propagating in the drift gap of a linear induction accelerator with collective focusing is studied using 3D numerical simulations in the framework of the full system of the Vlasov–Maxwell equations (code KARAT). The ion beam is neutralized by a comoving electron beam in the current density and, partially, in space charge, since the velocities of electrons and ions differ substantially. The dynamics of the high-current ion beam is investigated for different versions of additional neutralization of its space charge. It is established that, for a given configuration of the magnetic field and in the presence of a specially programmed injection of additional electrons from the boundary opposite to the ion injection boundary, the angular divergence of the ion beam almost vanishes, whereas the current of the ion beam at the exit from the accelerator drift gap changes insignificantly and the beam remains almost monoenergetic.

  19. Transportation of high-current ion and electron beams in the accelerator drift gap in the presence of an additional electron background

    International Nuclear Information System (INIS)

    The dynamics of a high-current ion beam propagating in the drift gap of a linear induction accelerator with collective focusing is studied using 3D numerical simulations in the framework of the full system of the Vlasov–Maxwell equations (code KARAT). The ion beam is neutralized by a comoving electron beam in the current density and, partially, in space charge, since the velocities of electrons and ions differ substantially. The dynamics of the high-current ion beam is investigated for different versions of additional neutralization of its space charge. It is established that, for a given configuration of the magnetic field and in the presence of a specially programmed injection of additional electrons from the boundary opposite to the ion injection boundary, the angular divergence of the ion beam almost vanishes, whereas the current of the ion beam at the exit from the accelerator drift gap changes insignificantly and the beam remains almost monoenergetic

  20. Transportation of high-current ion and electron beams in the accelerator drift gap in the presence of an additional electron background

    Science.gov (United States)

    Karas', V. I.; Kornilov, E. A.; Manuilenko, O. V.; Tarakanov, V. P.; Fedorovskaya, O. V.

    2015-12-01

    The dynamics of a high-current ion beam propagating in the drift gap of a linear induction accelerator with collective focusing is studied using 3D numerical simulations in the framework of the full system of the Vlasov-Maxwell equations (code KARAT). The ion beam is neutralized by a comoving electron beam in the current density and, partially, in space charge, since the velocities of electrons and ions differ substantially. The dynamics of the high-current ion beam is investigated for different versions of additional neutralization of its space charge. It is established that, for a given configuration of the magnetic field and in the presence of a specially programmed injection of additional electrons from the boundary opposite to the ion injection boundary, the angular divergence of the ion beam almost vanishes, whereas the current of the ion beam at the exit from the accelerator drift gap changes insignificantly and the beam remains almost monoenergetic.

  1. Antimicrobial Peptides (AMPs

    Directory of Open Access Journals (Sweden)

    Mehrzad Sadredinamin

    2016-04-01

    Full Text Available Antimicrobial peptides (AMPs are extensive group of molecules that produced by variety tissues of invertebrate, plants, and animal species which play an important role in their immunity response. AMPs have different classifications such as; biosynthetic machines, biological sources, biological functions, molecular properties, covalent bonding patterns, three dimensional structures, and molecular targets.These molecules have multidimensional properties including antimicrobial activity, antiviral activity, antifungal activity, anti-parasite activity, biofilm control, antitumor activity, mitogens activity and linking innate to adaptive immunity that making them promising agents for therapeutic drugs. In spite of this advantage of AMPs, their clinical developments have some limitation for commercial development. But some of AMPs are under clinical trials for the therapeutic purpose such as diabetic foot ulcers, different bacterial infections and tissue damage. In this review, we emphasized on the source, structure, multidimensional properties, limitation and therapeutic applications of various antimicrobial peptides.

  2. Investigations of Beam Dynamics Issues at Current and Future Hadron Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Ellison, James [Univ. of New Mexico, Albuquerque, NM (United States); Lau, Stephen [Univ. of New Mexico, Albuquerque, NM (United States); Heinemann, Klaus [Univ. of New Mexico, Albuquerque, NM (United States); Bizzozero, David [Univ. of New Mexico, Albuquerque, NM (United States)

    2015-03-12

    Final Report Abstract for DE-FG02-99ER4110, May 15, 2011- October 15, 2014 There is a synergy between the fields of Beam Dynamics (BD) in modern particle accelerators and Applied Mathematics (AMa). We have formulated significant problems in BD and have developed and applied tools within the contexts of dynamical systems, topological methods, numerical analysis and scientific computing, probability and stochastic processes, and mathematical statistics. We summarize the three main areas of our AMa work since 2011. First, we continued our study of Vlasov-Maxwell systems. Previously, we developed a state of the art algorithm and code (VM3@A) to calculate coherent synchrotron radiation in single pass systems. In this cycle we carefully analyzed the major expense, namely the integral-over-history (IOH), and developed two approaches to speed up integration. The first strategy uses a representation of the Bessel function J0 in terms of exponentials. The second relies on “local sequences” developed recently for radiation boundary conditions, which are used to reduce computational domains. Although motivated by practicality, both strategies involve interesting and rather deep analysis and approximation theory. As an alternative to VM3@A, we are integrating Maxwell’s equations by a time-stepping method, bypass- ing the IOH, using a Discontinuous Galerkin (DG) method. DG is a generalization of Finite Element and Finite Volume methods. It is spectrally convergent, unlike the commonly used Finite Difference methods, and can handle complicated vacuum chamber geometries. We have applied this in several contexts and have obtained very nice results including an explanation of an experiment at the Canadian Light Source, where the geometry is quite complex. Second, we continued our study of spin dynamics in storage rings. There is much current and proposed activity where spin polarized beams are being used in testing the Standard Model and its modifications. Our work has focused

  3. Design study of a new antenna system for steering microwave beam in electron cyclotron heating/current drive system

    International Nuclear Information System (INIS)

    The reflector driven in the linear motion to steer the microwave beam for electron cyclotron heating/current drive system, which has considerable merits, especially for reactor environments, has been studied in design. In a typical design, a microwave beam launched from the end of a waveguide is reflected at a concave mirror following a fixed flat mirror. The injection angle can be changed by varying a point of reflection on the concave mirror because of the transition of the normal angle of the concave mirror. The point of reflection is easily controlled by the linear motion of the concave mirror. It is notable that mirror rotation is not required, and the inside of a robust driving shaft can be used to supply the coolant to the mirror. This indicates that the antenna can be designed without a rotation axis, bearings, and a flexible cooling tube close to the plasma which may require frequent maintenance or replacement in a highly radioactive environment. This study shows that the antenna driven in the linear motion has a potential to meet certain specifications, especially with regard to antenna size, steerable range of the beam angle, and beam quality for experiments in tokamaks and for fusion reactors. In the preliminary design trial for the ITER equatorial antenna, the concaved mirror of 0.3 m in length having 1 m curvature and stroke of 0.2 m enables beam angle range of 20-40 deg. with beam radius of 0.06 m at the EC resonance

  4. An improved pulse-line accelerator-driven, intense current-density, and high-brightness pseudospark electron beam

    International Nuclear Information System (INIS)

    A high-voltage (200 kV), high current-density, low-emittance (23 π·mm mrd), high-brightness (8 x 1010 A/(mrd)2) electron beam was generated in a pseudospark chamber filled with 15 Pa nitrogen and driven by a modified pulse line accelerator. The beam ejected with ≤1-mm diameter, 2.2-kA beam current, 400-ns pulse length, and about 20 cm propagation distance. Exposure of 10 shots on the same film produced a hole of 1.6-mm diameter at 7 cm downstream of the anode, and showed its good reproducibility. After 60 shots, it was observed that almost no destructive damage traces were left on the surfaces of the various electrodes and insulators of the pseudospark discharge chamber. It was experimentally found that the quality of the pseudospark electron beam remains very high, even at high voltages (of several hundred kilovolts), similar to low voltages, and is much better than the quality of the cold-cathode electron beams

  5. Improved wear resistance of Al-15Si alloy with a high current pulsed electron beam treatment

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Y. [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Gao, B., E-mail: surfgao@yahoo.com.cn [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Tu, G.F.; Li, S.W. [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Dong, C. [Key Laboratory of the Ministry of Education of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Dalian 116024 (China); Zhang, Z.G. [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China)

    2011-07-01

    Highlights: > Firstly, Raman spectra are used to research the variation of Si structure before and after HCPEB treatment for the first time. > Secondly, a fine structure, namely the precipitation of nanocrystalline Si particles, is formed in the surface layer of the HCPEB-treated sample. > Thirdly, the relative wear resistance of an Al-15Si alloy surface is effectively enhanced by a factor of 9 after 15 pulse treatment. - Abstract: A hypereutectic Al-15Si alloy (Si 15 wt.%, Al balance) was irradiated by high current pulsed electron beam (HCPEB). The HCPEB treatment causes ultra-rapid heating, melting and cooling at the top surface layer. As a result, the special 'halo' microstructure centering on the primary Si phase is formed on the surface due to interdiffusion of Al and Si elements. The composition of the 'halo' microstructure is distributed continuously from the center to the edge of the 'halo'. Compared to an untreated matrix, the remelted layer underneath the surface presents single contrast because of the compositional homogeneity after HCPEB treatment. The thickness of the remelted layer increases slightly from 4.4 {mu}m (5 pulses) to 5.6 {mu}m (25 pulses). HCPEB treatment broadens and shifts the diffraction peaks of Al and Si. The lattice parameters of Al decreases due to the formation of a supersaturated solid solution of Al in the melted layer. Through analysis of Raman spectra and transmission electron microscopy (TEM), the amorphous Si (a-Si) and nanocrystalline Si are formed in the near-surface region under multiple bombardments of HCPEB. The relative wear resistance of a 15-pulse sample is effectively improved by a factor of 9, which can be attributed to the formation of metastable structures.

  6. Surface modification of Al-20Si alloy by high current pulsed electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Y. [School of Materials and Metallurgy, Northeastern University, Shenyang, 110004 (China); Gao, B., E-mail: surfgao@yahoo.com.cn [School of Materials and Metallurgy, Northeastern University, Shenyang, 110004 (China); Tu, G.F.; Li, S.W. [School of Materials and Metallurgy, Northeastern University, Shenyang, 110004 (China); Hao, S.Z.; Dong, C. [Key Laboratory of the Ministry of Education of Materials Modification by Laser, Ion and Electron Beams Dalian University of Technology, Dailan 116024 (China)

    2011-02-15

    Hypereutectic Al-20Si (Si 20 wt.%, Al balance)alloy surface was treated with high current pulsed electron beam (HCPEB) under different pulse numbers. The results indicate that HCPEB irradiation induces the formation of metastable structures on the treated surface. The coarse primary Si particle melts, producing a 'halo' microstructure with primary Si as the center on the melted surface. A supersaturated solid solution of Al is formed in the melted layer caused by Si atoms dissolving into the Al matrix. Cross-section structure analysis shows that a 4 {mu}m remelted layer is formed underneath the top surface of the HCEPB-treated sample. Compared with the matrix, the Al and Si elements in the remelted layer are distributed uniformly. In addition, the grains of the Al-20Si alloy surface are refined after HCPEB treatment, as shown by TEM observation. Nano-silicon particles are dispersed on the surface of remelted layer. Polygonal subgrains, approximately 50-100 nm in size, are formed in the Al matrix. The hardness test results show that the microhardness of the {alpha}(Al) and eutectic structure is increased with increasing pulse number. The hardness of the 'halo' microstructure presents a gradient change after 15 pulse treatment due to the diffusion of Si atoms. Furthermore, hardness tests of the cross-section at different depths show that the microhardness of the remelted layer is higher than that of the matrix. Therefore, HCPEB technology is a good surface modification method for enhancing the surface hardness of hypereutectic Al-20Si alloy.

  7. High-current relativistic electron beam shaping in a coaxial diode with magnetic insulation

    International Nuclear Information System (INIS)

    Solution of the problem of relativistic electron beam (REB) for the system with a constant transverse cross-section and thin-wall tubular cathode in an arbitrary magnetic field is presented. The total equation system determining REB parameters as a function of external longitudinal magnetic field is obtained on the base on the laws of conservation of impulse flow and momentum of electron impulse and fields (electrical and magnetic) under the assumption of the electron beam. Calculation results carried out with provision for a diamagnetism and screening of the beam impulse magnetic field by metal are in a good agreement with experimental data

  8. Clinical utility of dental cone-beam computed tomography: current perspectives

    Directory of Open Access Journals (Sweden)

    Jaju PP

    2014-04-01

    Full Text Available Prashant P Jaju,1 Sushma P Jaju21Oral Medicine and Radiology, 2Conservative Dentistry and Endodontics, Rishiraj College of Dental Sciences and Research Center, Bhopal, IndiaAbstract: Panoramic radiography and computed tomography were the pillars of maxillofacial diagnosis. With the advent of cone-beam computed tomography, dental practice has seen a paradigm shift. This review article highlights the potential applications of cone-beam computed tomography in the fields of dental implantology and forensic dentistry, and its limitations in maxillofacial diagnosis.Keywords: dental implants, cone-beam computed tomography, panoramic radiography, computed tomography

  9. Radiation damage in single crystal CVD diamond material investigated with a high current relativistic 197Au beam

    International Nuclear Information System (INIS)

    Single-crystal Chemical Vapor Deposition (ScCVD) diamond based prototype detectors have been constructed for the high intensity heavy ion experiments HADES and CBM at the future FAIR facility at GSI Darmstadt. Their properties have been studied with a high current density beam (about 2–3×106/s/mm2) of 1.25A GeV 197Au69+ ions. Details of the design, the intrinsic properties of the detectors and their performance after irradiation with such a beam are reported

  10. Preliminary results concerning the simulation of beam profiles from extracted ion current distributions for mini-STRIKE

    Science.gov (United States)

    Agostinetti, P.; Giacomin, M.; Serianni, G.; Veltri, P.; Bonomo, F.; Schiesko, L.

    2016-02-01

    The Radio Frequency (RF) negative hydrogen ion source prototype has been chosen for the ITER neutral beam injectors due to its optimal performances and easier maintenance demonstrated at Max-Planck-Institut für Plasmaphysik, Garching in hydrogen and deuterium. One of the key information to better understand the operating behavior of the RF ion sources is the extracted negative ion current density distribution. This distribution—influenced by several factors like source geometry, particle drifts inside the source, cesium distribution, and layout of cesium ovens—is not straightforward to be evaluated. The main outcome of the present contribution is the development of a minimization method to estimate the extracted current distribution using the footprint of the beam recorded with mini-STRIKE (Short-Time Retractable Instrumented Kalorimeter). To accomplish this, a series of four computational models have been set up, where the output of a model is the input of the following one. These models compute the optics of the ion beam, evaluate the distribution of the heat deposited on the mini-STRIKE diagnostic calorimeter, and finally give an estimate of the temperature distribution on the back of mini-STRIKE. Several iterations with different extracted current profiles are necessary to give an estimate of the profile most compatible with the experimental data. A first test of the application of the method to the BAvarian Test Machine for Negative ions beam is given.

  11. Preliminary results concerning the simulation of beam profiles from extracted ion current distributions for mini-STRIKE

    Energy Technology Data Exchange (ETDEWEB)

    Agostinetti, P., E-mail: piero.agostinetti@igi.cnr.it; Serianni, G.; Veltri, P. [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova (Italy); Giacomin, M. [Physics Department, Università di Padova, via F. Marzolo 8, 35131 Padova (Italy); Bonomo, F.; Schiesko, L. [Max-Planck-Institut für Plasmaphysik, Boltzmannstrasse 2, D-85748 Garching (Germany)

    2016-02-15

    The Radio Frequency (RF) negative hydrogen ion source prototype has been chosen for the ITER neutral beam injectors due to its optimal performances and easier maintenance demonstrated at Max-Planck-Institut für Plasmaphysik, Garching in hydrogen and deuterium. One of the key information to better understand the operating behavior of the RF ion sources is the extracted negative ion current density distribution. This distribution—influenced by several factors like source geometry, particle drifts inside the source, cesium distribution, and layout of cesium ovens—is not straightforward to be evaluated. The main outcome of the present contribution is the development of a minimization method to estimate the extracted current distribution using the footprint of the beam recorded with mini-STRIKE (Short-Time Retractable Instrumented Kalorimeter). To accomplish this, a series of four computational models have been set up, where the output of a model is the input of the following one. These models compute the optics of the ion beam, evaluate the distribution of the heat deposited on the mini-STRIKE diagnostic calorimeter, and finally give an estimate of the temperature distribution on the back of mini-STRIKE. Several iterations with different extracted current profiles are necessary to give an estimate of the profile most compatible with the experimental data. A first test of the application of the method to the BAvarian Test Machine for Negative ions beam is given.

  12. Robust, easily shaped, and epoxy-free carbon-fiber-aluminum cathodes for generating high-current electron beams

    Science.gov (United States)

    Liu, Lie; Li, Limin; Wen, Jianchun; Wan, Hong

    2009-02-01

    This paper presents the construction of carbon-fiber-aluminum (CFA) cathode by squeezing casting and its applications for generating high-current electron beams to drive high-power microwave sources. The fabrication process avoided using epoxy, a volatile deteriorating the vacuum system. These cathodes had a higher hardness than conventional aluminum, facilitating machining. After surface treatment, carbon fibers became the dominator determining emission property. A multineedle CFA cathode was utilized in a triode virtual cathode oscillator (vircator), powered by a ˜450 kV, ˜400 ns pulse. It was found that 300-400 MW, ˜250 ns microwave was radiated at a dominant frequency of 2.6 GHz. Further, this cathode can endure high-current-density emission without detectable degradation in performance as the pulse shot proceeded, showing the robust nature of carbon fibers as explosive emitters. Overall, this new class of cold cathodes offers a potential prospect of developing high-current electron beam sources.

  13. Agile manufacturing prototyping system (AMPS)

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, P.

    1998-05-09

    The Agile Manufacturing Prototyping System (AMPS) is being integrated at Sandia National Laboratories. AMPS consists of state of the industry flexible manufacturing hardware and software enhanced with Sandia advancements in sensor and model based control; automated programming, assembly and task planning; flexible fixturing; and automated reconfiguration technology. AMPS is focused on the agile production of complex electromechanical parts. It currently includes 7 robots (4 Adept One, 2 Adept 505, 1 Staubli RX90), conveyance equipment, and a collection of process equipment to form a flexible production line capable of assembling a wide range of electromechanical products. This system became operational in September 1995. Additional smart manufacturing processes will be integrated in the future. An automated spray cleaning workcell capable of handling alcohol and similar solvents was added in 1996 as well as parts cleaning and encapsulation equipment, automated deburring, and automated vision inspection stations. Plans for 1997 and out years include adding manufacturing processes for the rapid prototyping of electronic components such as soldering, paste dispensing and pick-and-place hardware.

  14. Investigation of chemical vapour deposition diamond detectors by X- ray micro-beam induced current and X-ray micro-beam induced luminescence techniques

    CERN Document Server

    Olivero, P; Vittone, E; Fizzotti, F; Paolini, C; Lo Giudice, A; Barrett, R; Tucoulou, R

    2004-01-01

    Tracking detectors have become an important ingredient in high-energy physics experiments. In order to survive the harsh detection environment of the Large Hadron Collider (LHC), trackers need to have special properties. They must be radiation hard, provide fast collection of charge, be as thin as possible and remove heat from readout electronics. The unique properties of diamond allow it to fulfill these requirements. In this work we present an investigation of the charge transport and luminescence properties of "detector grade" artificial chemical vapour deposition (CVD) diamond devices developed within the CERN RD42 collaboration, performed by means of X-ray micro-beam induced current collection (XBICC) and X-ray micro- beam induced luminescence (XBIL) techniques. XBICC technique allows quantitative estimates of the transport parameters of the material to be evaluated and mapped with micrometric spatial resolution. In particular, the high resolution and sensitivity of the technique has allowed a quantitati...

  15. Clinical utility of dental cone-beam computed tomography: current perspectives

    OpenAIRE

    Jaju PP; Jaju SP

    2014-01-01

    Prashant P Jaju,1 Sushma P Jaju21Oral Medicine and Radiology, 2Conservative Dentistry and Endodontics, Rishiraj College of Dental Sciences and Research Center, Bhopal, IndiaAbstract: Panoramic radiography and computed tomography were the pillars of maxillofacial diagnosis. With the advent of cone-beam computed tomography, dental practice has seen a paradigm shift. This review article highlights the potential applications of cone-beam computed tomography in the fields of dental implantology an...

  16. Proton Beam Therapy for Non-Small Cell Lung Cancer: Current Clinical Evidence and Future Directions

    OpenAIRE

    Berman, Abigail T.; Sara St. James; Ramesh Rengan

    2015-01-01

    Lung cancer is the leading cancer cause of death in the United States. Radiotherapy is an essential component of the definitive treatment of early-stage and locally-advanced lung cancer, and the palliative treatment of metastatic lung cancer. Proton beam therapy (PBT), through its characteristic Bragg peak, has the potential to decrease the toxicity of radiotherapy, and, subsequently improve the therapeutic ratio. Herein, we provide a primer on the physics of proton beam therapy for lung canc...

  17. Development of microwave ion source and low energy beam transport system for high current cyclotron

    Energy Technology Data Exchange (ETDEWEB)

    Pandit, V.S., E-mail: pandit@vecc.gov.in; Sing Babu, P.; Goswami, A.; Srivastava, S.; Misra, A.; Chatterjee, Mou; Nabhiraj, P.Y.; Yadav, R.C.; Bhattacharya, S.; Roy, S.; Nandi, C.; Pal, G.; Thakur, S.K.

    2013-12-15

    A 2.45 GHz microwave ion source and a low energy beam transport system have been developed to study the high intensity proton beam injection into a 10 MeV, 5 mA compact cyclotron. We have extracted proton beam more than 10 mA at 80 kV as measured by the DCCT after the extraction and a well collimated beam of 7 mA (through 1 cm × 1 cm slit) at the faraday cup 1.5 m away from the source. The transport of protons from the ion source in the presence of H{sub 2}{sup +}, H{sub 3}{sup +} species has been studied using PIC simulations through our transport line which consists of two solenoids. We have also installed a small dipole magnet with similar field as that of the cyclotron along with vacuum chamber, spiral inflector and few diagnostic elements at the end of the beam line. In the preliminary testing of inflection, we achieved 1 mA beam on the faraday cup at the exit of inflector with ∼60% transmission efficiency.

  18. Measurement of neutral current neutral pion production on Carbon in a Few-GeV Neutrino Beam

    OpenAIRE

    Kurimoto, Y

    2009-01-01

    The SciBooNE Collaboration has measured neutral current neutral pion production by the muon neutrino beam at a polystyrene target (C8H8). We obtained (7.7+- 0.5(stat.)+0.4-0.5 (sys.)) x 10^-2 as cross section ratio of the neutral current neutral pion production to total charged current cross section at the mean neutrino energy of 1.16 GeV. This result is consistent with the Monte Carlo prediction based on the Rein-Sehgal model

  19. Precision current sensing and monitoring for the inflector beam of K-500 superconducting cyclotron at VECC Kolkata

    International Nuclear Information System (INIS)

    The spiral Inflector of the K-500 Superconducting Cyclotron at VECC Kolkata consists of two electrodes system for bending of ions from the axial to median plane of the cyclotron. These two electrodes float potential of + 10 kV and -10kV maximum to give required electric field for proper beam bending. It is required to monitor and track the beam falling on the inflector plate from the control room while tuning the beam. Hence a precision current sensing mechanism in high side has been developed in PSI, VECC and commissioned. In this the following components have been used. (1) Precision high voltage, 50 ppm stable resistive shunt, (2) Precision, Low drift Operational Amplifier, (3) Precision V-F converter, (4) 25 KV High Frequency lsolation Transformer and (5) LabJack module for PC interface. The system is in operation. This paper describes the operation of the circuit ant the test report. (author)

  20. Acceleration of 1 MeV H- Ion Beams at ITER NB-relevant High Current Density

    International Nuclear Information System (INIS)

    Full text: ITER neutral beam (NB) system requires deuterium negative ion beams of 1 MeV, 40 A at the current density of 200 A/m2 from a single large negative ion source and an accelerator. This paper summarizes progress in R and D with a reduced size accelerator, so-called 'the MeV accelerator' at Japan Atomic Energy Agency (JAEA). In the last Fusion Energy Conference, we reported achievement of 1 MV voltage holding in vacuum for more than one hour. Physics of beamlet deflections due to their own space charges and magnetic field was also reported utilizing a sophisticated three dimensional beam trajectory analyses. The improved voltage holding and a trajectory compensation technique have been applied to the MeV accelerator. Many discharge burn marks have been observed inside the accelerator after long pulse operation reported in the last conference. It was turned out that such discharge marks were observed at positions facing to high local electric field, such as edges, corners, and steps between grid and its support. In the present MeV accelerator, such positions have been modified, for example, by increasing radii of corners around grid supports, and increasing gap length between grids to lower the local electric concentrations to about 3 - 4 kV/mm. For compensation of magnetic deflection, aperture offset was applied at the bottom of the EXG. Magnetic field is formed by small permanent magnets embedded in EXG between aperture lines. Since the polarities are arranged so as to be alternative in each line between apertures, aperture offset of 0.8 mm was defined in the direction against the magnetic deflection. To counteract the beamlet deflection by space charge repulsion, a field shaping plate, a metal plate to deform electric field, were installed around the aperture area for deflection of outermost beamlet inward. Position and thickness of the plate was designed by the analyses. It should be highlighted that reduction of beam direct interception at grids has

  1. Electron-Cloud Simulation and Theory for High-Current Heavy-Ion Beams

    International Nuclear Information System (INIS)

    Stray electrons can arise in positive-ion accelerators for heavy ion fusion or other applications as a result of ionization of ambient gas or gas released from walls due to halo-ion impact, or as a result of secondary- electron emission. We summarize the distinguishing features of electron cloud issues in heavy-ion-fusion accelerators and a plan for developing a self-consistent simulation capability for heavy-ion beams and electron clouds. We also present results from several ingredients in this capability: (1) We calculate the electron cloud produced by electron desorption from computed beam-ion loss, which illustrates the importance of retaining ion reflection at the walls. (2) We simulate of the effect of specified electron cloud distributions on ion beam dynamics. We consider here electron distributions with axially varying density, centroid location, or radial shape, and examine both random and sinusoidally varying perturbations. We find that amplitude variations are most effective in spoiling ion beam quality, though for sinusoidal variations which match the natural ion beam centroid oscillation or breathing mode frequencies, the centroid and shape perturbations can also have significant impact. We identify an instability associated with a resonance between the beam-envelope ''breathing'' mode and the electron perturbation. We estimate its growth rate, which is moderate (compared to the reciprocal of a typical pulse duration). One conclusion from this study is that heavy-ion beams are surprisingly robust to electron clouds, compared to a priori expectations. (3) We report first results from a long-timestep algorithm for electron dynamics, which holds promise for efficient simultaneous solution of electron and ion dynamics

  2. THE n-DISTRIBUTION OF ELECTRONS AND DOUBLE LAYERS IN THE ELECTRON-BEAM-RETURN-CURRENT SYSTEM OF SOLAR FLARES

    International Nuclear Information System (INIS)

    We investigate processes in the electron-beam-return-current system in the impulsive phase of solar flares to answer a question about the formation of the n-electron distribution detected in this phase of solar flares. An evolution of the electron-beam-return-current system with an initial local density depression is studied using a three-dimensional electromagnetic particle-in-cell model. In the system the strong double layer is formed. Its electric field potential increases with the electron beam flux. In this electric field potential, the electrons of background plasma are strongly accelerated and propagate in the return-current direction. The high-energy part of their distribution at the high-potential side of the strong double layer resembles that of the n-distribution. Thus, the detection of the n-distributions, where a form of the high-energy part of the distribution is the most important, can indicate the presence of strong double layers in solar flares. The similarity between processes in solar flare loops and those in the downward current region of the terrestrial aurora, where the double layers were observed by FAST satellite, supports this idea.

  3. The structure and properties of boron carbide ceramics modified by high-current pulsed electron-beam

    Science.gov (United States)

    Ivanov, Yuri; Tolkachev, Oleg; Petyukevich, Maria; Teresov, Anton; Ivanova, Olga; Ikonnikova, Irina; Polisadova, Valentina

    2016-01-01

    The present work is devoted to numerical simulation of temperature fields and the analysis of structural and strength properties of the samples surface layer of boron carbide ceramics treated by the high-current pulsed electron-beam of the submillisecond duration. The samples made of sintered boron carbide ceramics are used in these investigations. The problem of calculating the temperature field is reduced to solving the thermal conductivity equation. The electron beam density ranges between 8…30 J/cm2, while the pulse durations are 100…200 μs in numerical modelling. The results of modelling the temperature field allowed ascertaining the threshold parameters of the electron beam, such as energy density and pulse duration. The electron beam irradiation is accompanied by the structural modification of the surface layer of boron carbide ceramics either in the single-phase (liquid or solid) or two-phase (solid-liquid) states. The sample surface of boron carbide ceramics is treated under the two-phase state (solid-liquid) conditions of the structural modification. The surface layer is modified by the high-current pulsed electron-beam produced by SOLO installation at the Institute of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk, Russia. The elemental composition and the defect structure of the modified surface layer are analyzed by the optical instrument, scanning electron and transmission electron microscopes. Mechanical properties of the modified layer are determined measuring its hardness and crack resistance. Research results show that the melting and subsequent rapid solidification of the surface layer lead to such phenomena as fragmentation due to a crack network, grain size reduction, formation of the sub-grained structure due to mechanical twinning, and increase of hardness and crack resistance.

  4. The structure and properties of boron carbide ceramics modified by high-current pulsed electron-beam

    International Nuclear Information System (INIS)

    The present work is devoted to numerical simulation of temperature fields and the analysis of structural and strength properties of the samples surface layer of boron carbide ceramics treated by the high-current pulsed electron-beam of the submillisecond duration. The samples made of sintered boron carbide ceramics are used in these investigations. The problem of calculating the temperature field is reduced to solving the thermal conductivity equation. The electron beam density ranges between 8…30 J/cm2, while the pulse durations are 100…200 μs in numerical modelling. The results of modelling the temperature field allowed ascertaining the threshold parameters of the electron beam, such as energy density and pulse duration. The electron beam irradiation is accompanied by the structural modification of the surface layer of boron carbide ceramics either in the single-phase (liquid or solid) or two-phase (solid-liquid) states. The sample surface of boron carbide ceramics is treated under the two-phase state (solid-liquid) conditions of the structural modification. The surface layer is modified by the high-current pulsed electron-beam produced by SOLO installation at the Institute of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk, Russia. The elemental composition and the defect structure of the modified surface layer are analyzed by the optical instrument, scanning electron and transmission electron microscopes. Mechanical properties of the modified layer are determined measuring its hardness and crack resistance. Research results show that the melting and subsequent rapid solidification of the surface layer lead to such phenomena as fragmentation due to a crack network, grain size reduction, formation of the sub-grained structure due to mechanical twinning, and increase of hardness and crack resistance

  5. Microstructure modifications and corrosion behaviors of Cr4Mo4V steel treated by high current pulsed electron beam

    International Nuclear Information System (INIS)

    Research highlights: → Using high energy pulsed electron beam to modify Cr4Mo4V steel surface properties. → Electron beam irradiation induces crater-like defects on the surface of the steel. → After irradiation, retained austenite formed in the remelted layer of the steel. → Electron beam irradiation improves the corrosion resistance of the steel. - Abstract: In this work, Cr4Mo4V steel was irradiated by high energy current pulsed electron beam (HCPEB) with energy density of 6 J/cm2. Morphology and phase composition of the surface layer were analyzed using scanning electron microscopy (SEM) and glancing angle X-ray diffraction (GXRD). The crater-like morphology was observed on surface after HCPEB treatment, and the thickness of melted layer was ∼7 μm. Results from GXRD revealed that HCPEB treatment could suppress martensite transition and the content of retained austenite in the melted layer increased with irradiation number. The corrosion resistance was evaluated by electrochemical polarization tests in neutral 3.5% NaCl solution. Compared with the untreated Cr4Mo4V steel, corrosion potential of the samples treated by HCPEB improved and the corrosion current density decreased. The improved corrosion resistance is attributed to the absence of the carbide, formation of retained austenite and dissolution of alloy elements, particularly of Cr and Mo, into the matrix.

  6. The new GSI prestripper linac for high current heavy ion beams

    International Nuclear Information System (INIS)

    The original UNILAC injector uses PENNING type ion sources and charge states up to 10+ for uranium beams. The beam intensities for very heavy ion species out of that injector are too low by almost a factor 300 to fill the Heavy Ion Synchrotron SIS up to its space charge limit. At present only ion sources like CHORDIS (1+ and 2+ charged ions) or MEVVA, which generates charge states up to 4+ above mass 180 can provide the requested beam intensities during a pulse duration of 100 μs. The IH-DTL with its high acceleration efficiency offers the possibility to replace the 34 MV prestripper linac by a new 91 MV linac while keeping the positions of the pre-injectors and of the gas stripper untouched. The actual prestripper frequency of 27 MHz will be replaced by 36 MHz, being one third of the poststripper linac frequency. The beam dynamics of 'Combined Zero Degree Synchronous Particle Sections' is applied on the two IH cavities.They generate averaged effective voltage gains of 4.3 MV/m. The paper describes the new linac, especially focusing on the rf structures and on the beam dynamics along the IH-DTL. (author)

  7. Proton Beam Therapy for Non-Small Cell Lung Cancer: Current Clinical Evidence and Future Directions

    Energy Technology Data Exchange (ETDEWEB)

    Berman, Abigail T., E-mail: abigail.berman@uphs.upenn.edu [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104 (United States); James, Sara St.; Rengan, Ramesh [Department of Radiation Oncology, University of Washington Medical Center, Seattle, WA 98195 (United States)

    2015-07-02

    Lung cancer is the leading cancer cause of death in the United States. Radiotherapy is an essential component of the definitive treatment of early-stage and locally-advanced lung cancer, and the palliative treatment of metastatic lung cancer. Proton beam therapy (PBT), through its characteristic Bragg peak, has the potential to decrease the toxicity of radiotherapy, and, subsequently improve the therapeutic ratio. Herein, we provide a primer on the physics of proton beam therapy for lung cancer, present the existing data in early-stage and locally-advanced non-small cell lung cancer (NSCLC), as well as in special situations such as re-irradiation and post-operative radiation therapy. We then present the technical challenges, such as anatomic changes and motion management, and future directions for PBT in lung cancer, including pencil beam scanning.

  8. Proton Beam Therapy for Non-Small Cell Lung Cancer: Current Clinical Evidence and Future Directions

    International Nuclear Information System (INIS)

    Lung cancer is the leading cancer cause of death in the United States. Radiotherapy is an essential component of the definitive treatment of early-stage and locally-advanced lung cancer, and the palliative treatment of metastatic lung cancer. Proton beam therapy (PBT), through its characteristic Bragg peak, has the potential to decrease the toxicity of radiotherapy, and, subsequently improve the therapeutic ratio. Herein, we provide a primer on the physics of proton beam therapy for lung cancer, present the existing data in early-stage and locally-advanced non-small cell lung cancer (NSCLC), as well as in special situations such as re-irradiation and post-operative radiation therapy. We then present the technical challenges, such as anatomic changes and motion management, and future directions for PBT in lung cancer, including pencil beam scanning

  9. Proton Beam Therapy for Non-Small Cell Lung Cancer: Current Clinical Evidence and Future Directions

    Directory of Open Access Journals (Sweden)

    Abigail T. Berman

    2015-07-01

    Full Text Available Lung cancer is the leading cancer cause of death in the United States. Radiotherapy is an essential component of the definitive treatment of early-stage and locally-advanced lung cancer, and the palliative treatment of metastatic lung cancer. Proton beam therapy (PBT, through its characteristic Bragg peak, has the potential to decrease the toxicity of radiotherapy, and, subsequently improve the therapeutic ratio. Herein, we provide a primer on the physics of proton beam therapy for lung cancer, present the existing data in early-stage and locally-advanced non-small cell lung cancer (NSCLC, as well as in special situations such as re-irradiation and post-operative radiation therapy. We then present the technical challenges, such as anatomic changes and motion management, and future directions for PBT in lung cancer, including pencil beam scanning.

  10. Optimal Design for Reactivity Ratio Estimation: A Comparison of Techniques for AMPS/Acrylamide and AMPS/Acrylic Acid Copolymerizations

    Directory of Open Access Journals (Sweden)

    Alison J. Scott

    2015-11-01

    Full Text Available Water-soluble polymers of acrylamide (AAm and acrylic acid (AAc have significant potential in enhanced oil recovery, as well as in other specialty applications. To improve the shear strength of the polymer, a third comonomer, 2-acrylamido-2-methylpropane sulfonic acid (AMPS, can be added to the pre-polymerization mixture. Copolymerization kinetics of AAm/AAc are well studied, but little is known about the other comonomer pairs (AMPS/AAm and AMPS/AAc. Hence, reactivity ratios for AMPS/AAm and AMPS/AAc copolymerization must be established first. A key aspect in the estimation of reliable reactivity ratios is design of experiments, which minimizes the number of experiments and provides increased information content (resulting in more precise parameter estimates. However, design of experiments is hardly ever used during copolymerization parameter estimation schemes. In the current work, copolymerization experiments for both AMPS/AAm and AMPS/AAc are designed using two optimal techniques (Tidwell-Mortimer and the error-in-variables-model (EVM. From these optimally designed experiments, accurate reactivity ratio estimates are determined for AMPS/AAm (rAMPS = 0.18, rAAm = 0.85 and AMPS/AAc (rAMPS = 0.19, rAAc = 0.86.

  11. Time structure of the particle beam source and current sheath filamentation in the plasma focus

    International Nuclear Information System (INIS)

    In previous work the authors have described a method for determining the energy spectrum N(E) of the ion beam emitted from a localized (point) source in the plasma focus pinch. In systematic applications the time structure of the beam source (dN/dt) is assumed to be the same as that of the x-ray localized source recorded from scintillation detector signal with a ≅ 2-5 ns time resolution [the spectrum is derived from the ion time of flight ΔtΓE/sup -1/2/; Δt from the conditions x(t)xMax N/Max x = N(t + Δt) on x-ray signal (x) and particle signal N]. The energy spectrum with a high resolution (ΔE ≤ 0.0 l E) from an alternative method - i.e. from magnetic analyzer data - is essentially the same as that from time of flight. This confirms that the time structure of the ion beam source in the high energy region (E > 0.3 MeV) fits the x-ray (and electron beam) source structure. At any specific time tau (i.e., within a sufficiently small time interval δt during the emission time ≅ 5-50 ns of the beam) the beam is emitted with an amplitude N(E) which is sharply peaked at a specific value of the energy E = E(tau). A correlation of the filamentary structure of the x-ray source with a filamentary structure of the ion source can also be established on a space scale of ≤ 10μm

  12. Beam space charge effects in high-current cyclotron injector CI-5

    International Nuclear Information System (INIS)

    Separated sector cyclotron-injector CI-5 has been studied in the framework of the external injection into phasotron project. The calculations of beam dynamics characteristics of Cyclotron CI-5 for H- beam of 5 MeV energy are presented. Space charge limits (both transverse and longitudinal) have been investigated. Analytical estimations and numerical simulations of particle motion taking into account space charge effects confirm that it is possible to achieve 10 mA in a 5 MeV separated sector H- Cyclotron

  13. Studies of high-current relativistic electron beam interaction with gas and plasma in Novosibirsk

    Science.gov (United States)

    Sinitsky, S. L.; Arzhannikov, A. V.; Burdakov, A. V.

    2016-03-01

    This paper presents an overview of the studies on the interaction of a high-power relativistic electron beam (REB) with dense plasma confined in a long open magnetic trap. The main goal of this research is to achieve plasma parameters close to those required for thermonuclear fusion burning. The experimental studies were carried over the course of four decades on various devices: INAR, GOL, INAR-2, GOL-M, and GOL-3 (Budker Institute of Nuclear Physics) for a wide range of beam and plasma parameters.

  14. Numerical Modeling of Annular High-Current Relativistic Beam Forming in a Toroidal Chamber with a Magnet

    Science.gov (United States)

    Bogdanovich, B. Yu.; L'vov, E. I.; Nesterovich, A. V.; Sukhanova, L. A.; Khlestkov, Yu. A.

    2016-04-01

    A scheme of forming an annular high-current relativistic beam (HCRB) from a directly propagating HCRB in a diode with magnetic insulation and toroidal chamber with a constant magnet is described. The code KARAT is used to analyze numerically the HCRB dynamics. It is demonstrated that for a proper relationship of the system parameters the directly propagating HCRB is rolled up into a torus.

  15. Arc and filament heater current control system for 5 MW ion source of neutral beam injector for SST1

    International Nuclear Information System (INIS)

    This paper presents control system used in managing power system deployed on 1.7 MW neutral beam injector at 80 kV. Power system consists of 24 arc discharge current power supplies (120 V, 80 A, DC), 8 filament heater power supplies (200V, 10 A, 400 Hz, AC) and one highly regulated high voltage power supply (80 kV, 60ADC)

  16. The switch interface and the interlock protection of the magnet power system of the beam current transport line

    International Nuclear Information System (INIS)

    The synchrotron radiation facility, constructed by the Hefei National Synchrotron Radiation Laboratory, University of Science and Technology of China, had passed the normal check by the state. The facility will be open to the users inside and outside the country. In this paper, the switch interface and the interlock protection of the magnet power system of the beam current transport line, one of the main components of this facility, are described

  17. Modified knife-edge method for current density distribution measurements in e-beam writers

    Czech Academy of Sciences Publication Activity Database

    Bok, Jan; Kolařík, Vladimír; Horáček, Miroslav; Matějka, Milan; Matějka, František

    2013-01-01

    Roč. 31, č. 3 (2013), 031603:1-6. ISSN 1071-1023 R&D Projects: GA MŠk ED0017/01/01; GA TA ČR TE01020118 Institutional support: RVO:68081731 Keywords : electron-beam * intensity distribution * aperture * detector * profile * size Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.358, year: 2013

  18. Operating results for the beam profile monitor system currently in use at Bevalac Facility

    International Nuclear Information System (INIS)

    Three stations of a soon to be completed multi-station, multi-wire beam monitoring system have been installed in the Bevalac transfer line. The following article will provide a cursory analysis of the electronic circuitry, discuss new design additions and summarize the operating results obtained over the last year

  19. A steering magnet optimized by random search method for high current beam transport line

    International Nuclear Information System (INIS)

    We present an improved design of the steering magnet which produces almost uniform magnetic field in the region through which beam passes. Optimization of the parameters of the steering magnet is done by random search method. It is shown that use of a suitable shim reduces the field deviation by a great extent. (author)

  20. Electron Beam-Plasma Interaction and the Return-Current Formation

    Czech Academy of Sciences Publication Activity Database

    Karlický, Marian

    2009-01-01

    Roč. 690, č. 1 (2009), s. 189-197. ISSN 0004-637X R&D Projects: GA AV ČR IAA300030701; GA MŠk(CZ) LC06014 Institutional research plan: CEZ:AV0Z10030501 Keywords : plasma instabilities * electron beams * solar flares Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 7.364, year: 2009

  1. Applying Mathematical Processes (AMP)

    Science.gov (United States)

    Kathotia, Vinay

    2011-01-01

    This article provides insights into the "Applying Mathematical Processes" resources, developed by the Nuffield Foundation. It features Nuffield AMP activities--and related ones from Bowland Maths--that were designed to support the teaching and assessment of key processes in mathematics--representing a situation mathematically, analysing,…

  2. AMP language reference manual

    International Nuclear Information System (INIS)

    The use of a program for symbolic calculations named AMP (Algebraic Manipulation Program) is described. Its main features are: high speed heart for usual algebraic calculations; conversational capability; derivation, substitutions, matricial calculus, expansions, non commutative algebrae...; possibility to define new symbols and associated rules; possibility to create and use external libraries; written for IBM/370 like computers

  3. Single crystal LaB6: a comparison with currently used thermionic cathodes for broad beam applications

    International Nuclear Information System (INIS)

    The use of single crystal LaB6 cathodes in microbeam applications has grown dramatically in the past few years, due to recognition of the high current density/low volatility characteristics of this material. We present here experimental results suggesting that advanced, single crystal LaB6 cathodes should also satisfy the requirements of broad beam applications, such as satellite-borne traveling wave tubes, where high current density, long lifetime and excellent stability and reproducibility are necessary. The most important parameters for cathode characterization are available emitted current density, material vaporization rate, lifetime and power consumption. Other important characteristics are activation procedure, resistance to poisoning by impurities, emission stability and emission uniformity across the cathode emitting surface. The current state of the art cathode type used in commercial devices is the impregnated dispenser cathode (IDC). The construction of such cathodes are outlined briefly, and their operating properties are discussed

  4. Comparisons of Monte Carlo calculations with absorbed dose determinations in flat materials using high-current, energetic electron beams

    International Nuclear Information System (INIS)

    International standards and guidelines for calibrating high-dose dosimetry systems to be used in industrial radiation processing recommend that dose-rate effects on dosimeters be evaluated under conditions of use. This is important when the irradiation relies on high-current electron accelerators, which usually provide very high dose-rates. However, most dosimeter calibration facilities use low-intensity gamma radiation or low-current electron accelerators, which deliver comparatively low dose-rates. Because of issues of thermal conductivity and response, portable calorimeters cannot be practically used with high-current accelerators, where product conveyor speeds under an electron beam can exceed several meters per second and the calorimeter is not suitable for use with product handling systems. As an alternative, Monte Carlo calculations can give theoretical estimates of the absorbed dose in materials with flat or complex configurations such that the results are independent of dose-rate. Monte Carlo results can then be compared to experimental dose determinations to see whether dose-rate effects in the dosimeters are significant. A Monte Carlo code has been used in this study to calculate the absorbed doses in alanine film dosimeters supported by flat sheets of plywood irradiated with electrons using incident energies extending from 1.0 MeV to 10 MeV with beam currents up to 30 mA. The same process conditions have been used for dose determinations with high-current electron beams using low dose-rate gamma calibrated alanine film dosimeters. The close agreement between these calculations and the dosimeter determinations indicates that the response of this type of dosimeter system is independent of the dose-rate, and provides assurance that Monte Carlo calculations can yield results with sufficient accuracy for many industrial applications

  5. Proton beam therapy and localised prostate cancer: current status and controversies

    OpenAIRE

    Efstathiou, J. A.; Gray, P. J.; Zietman, A L

    2013-01-01

    Proton therapy is a promising, but costly, treatment for prostate cancer. Theoretical physical advantages exist; yet to date, it has been shown only to be comparably safe and effective when compared with the alternatives and not necessarily superior. If clinically meaningful benefits do exist for patients, more rigorous study will be needed to detect them and society will require this to justify the investment of time and money. New technical advances in proton beam delivery coupled with shor...

  6. Effect of high current electron beam in a 30 MeV radio frequency linac for neutron-time-of-flight applications

    Energy Technology Data Exchange (ETDEWEB)

    Nayak, B., E-mail: biswaranjan.nayak1@gmail.com; Acharya, S.; Rajawat, R. K. [Accelerator and Pulsed Power Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); DasGupta, K. [Accelerator and Pulsed Power Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Beam Technology Development Group, BARC, Mumbai 400085 (India)

    2016-01-15

    A high power pulsed radio frequency electron linac is designed by BARC, India to accelerate 30 MeV, 10 A, 10 ns beam for neutron-time-of-flight applications. It will be used as a neutron generator and will produce ∼10{sup 12}–10{sup 13} n/s. It is essential to reduce the beam instability caused by space charge effect and the beam cavity interaction. In this paper, the wakefield losses in the accelerating section due to bunch of RMS (Root mean square) length 2 mm (at the gun exit) is analysed. Loss and kick factors are numerically calculated using CST wakefield solver. Both the longitudinal and transverse wake potentials are incorporated in beam dynamics code ELEGANT to find the transverse emittance growth of the beam propagating through the linac. Beam loading effect is examined by means of numerical computation carried out in ASTRA code. Beam break up start current has been estimated at the end of the linac which arises due to deflecting modes excited by the high current beam. At the end, transverse beam dynamics of such high current beam has been analysed.

  7. Effect of high current electron beam in a 30 MeV radio frequency linac for neutron-time-of-flight applications

    International Nuclear Information System (INIS)

    A high power pulsed radio frequency electron linac is designed by BARC, India to accelerate 30 MeV, 10 A, 10 ns beam for neutron-time-of-flight applications. It will be used as a neutron generator and will produce ∼1012–1013 n/s. It is essential to reduce the beam instability caused by space charge effect and the beam cavity interaction. In this paper, the wakefield losses in the accelerating section due to bunch of RMS (Root mean square) length 2 mm (at the gun exit) is analysed. Loss and kick factors are numerically calculated using CST wakefield solver. Both the longitudinal and transverse wake potentials are incorporated in beam dynamics code ELEGANT to find the transverse emittance growth of the beam propagating through the linac. Beam loading effect is examined by means of numerical computation carried out in ASTRA code. Beam break up start current has been estimated at the end of the linac which arises due to deflecting modes excited by the high current beam. At the end, transverse beam dynamics of such high current beam has been analysed

  8. Development of 2D particle-in-cell code to simulate high current, low energy beam in a beam transport system

    Indian Academy of Sciences (India)

    S C L Srivastava; S V L S Rao; P Singh

    2007-10-01

    A code for 2D space-charge dominated beam dynamics study in beam transport lines is developed. The code is used for particle-in-cell (PIC) simulation of -uniform beam in a channel containing solenoids and drift space. It can also simulate a transport line where quadrupoles are used for focusing the beam. Numerical techniques as well as the results of beam dynamics studies are presented in the paper.

  9. Measurement of charged current deep inelastic scattering cross sections with a longitudinally polarised electron beam at HERA

    International Nuclear Information System (INIS)

    Measurements of the cross sections for charged current deep inelastic scattering in e-p collisions with longitudinally polarised electron beams are presented. The measurements are based on a data sample with an integrated luminosity of 175 pb-1 collected with the ZEUS detector at HERA at a centre-of-mass energy of 318 GeV. The total cross section is given for positively and negatively polarised electron beams. The differential cross-sections dσ/dQ2, dσ/dx and dσ/dy are presented for Q2>200 GeV2. The double-differential cross-section d2σ/dxdQ2 is presented in the kinematic range 2802 and 0.015< x<0.65. The measured cross sections are compared with the predictions of the Standard Model. (orig.)

  10. Improving photoresponse characterization of dye-sensitized solar cells: application to the laser beam-induced current technique

    International Nuclear Information System (INIS)

    The photocurrent response of dye-sensitized solar cells (DSSCs) to light excitation from focused and non-focused laser beams is investigated. We observe that part of the photocurrent is produced by the activation of the irradiated area, whereas another part is generated by the previously photoexcited area. A mathematical algorithm has been devised to describe the rise and decay processes. The application of this algorithm leads to a significant improvement in the surface photoresponse and quantum yield measurements in DSSCs by means of the laser beam-induced current (LBIC) technique. This algorithm enhances the quality and definition of the LBIC images and opens the way to use this technique to cope with the biphasic features of these photovoltaic devices and extracting key properties for device performance such as internal quantum efficiencies and electron diffusion lengths

  11. Current density profile and electron beam localization measurements using carbon pellets on T-10

    International Nuclear Information System (INIS)

    The letter presents experimental evidence and an analysis of two phenomena arising during carbon pellet ablation - a toroidal trajectory deflection and enhanced localized ablation in the electron cyclotron resonance (ECR) current drive regime. A model developed for describing the toroidal deflection of a carbon pellet in a tokamak shows that the trajectory curvature is sensitive to the current density. Photography of the pellet trajectory is used as a diagnostic for the determination of the local current density in an ohmically heated plasma. Directly measured current profiles using pellets are in reasonable agreement with that obtained using the Spitzer conductivity, and current density fluctuations have been observed that are probably associated with magnetic islands. It is shown that in the ECR current drive regime on T-10, energetic electrons probably stimulated by the microwave power are located in a narrow zone (2 cm thickness in the radial direction) with sharp boundaries. (author). Letter-to-the-editor. 7 refs, 5 figs

  12. LETTER: Current density profile and electron beam localization measurements using carbon pellets on T-10

    Science.gov (United States)

    Egorov, S. M.; Kuteev, B. V.; Miroshnikov, I. V.; Mikhailenko, A. A.; Sergeev, V. Yu.; Ushakov, S. N.; Bagdasarov, A. A.; Chistyakov, V. V.; Elizavetin, D. Yu.; Vasin, N. L.

    1992-11-01

    The authors present experimental evidence and an analysis of two phenomena arising during carbon pellet ablation-a toroidal trajectory deflection and enhanced localized ablation in the electron cyclotron resonance (ECR) current drive regime. A model developed for describing the toroidal deflection of a carbon pellet in a tokamak shows that the trajectory curvature is sensitive to the current density. Photography of the pellet trajectory is used as a diagnostic for the determination of the local current density in an ohmically heated plasma. Directly measured current profiles using pellets are in reasonable agreement with that obtained using the Spitzer conductivity, and current density fluctuations have been observed that are probably associated with magnetic islands. It is shown that in the ECR current drive regime on T-10, energetic electrons probably stimulated by the microwave power are located in a narrow zone (2 cm thickness in the radial direction) with sharp boundaries

  13. Current status of medium and low energy electron beam accelerators and their applications

    International Nuclear Information System (INIS)

    Electron Beam (EB) use has been increasing in popularity as a crosslinking process over the past several years. Examples of EB use are heat resistance improvement of electric wires, high quality foamed polyethylene (PE) and polypropylene (PP), Automotive Tire manufacturing and heat-shrinkable film. EB process is used in the Tire manufacturing as a pre-vulcanization of rubber sheet before forming process. EB improves the green strength of rubber sheet and it makes it possible to maintain the shape or size of the original until completion of final vulcanization. It is said that this effect is useful for reducing the consumption of rubber material. The application of Low energy electron beam accelerators (low energy EB) is mainly used to cure resins or coatings and it has been gradually spreading to the industrial field such as pressure sensitive adhesives, release paper, transfer film, etc. Low energy EB curing is often compared with Ultra-Violet (UV) curing, but commercialized application indicate there is an advantage for the EB process. A typical advantage is that no initiators are required to start curing, which UV requires. EB curing may be used to supplement disadvantages of UV such as weatherability, color limitation, etc. In addition to these, EB process is spreading by using its original advantages, of high cross-link density, small heat influence on the substrate and no solvent requirement. EB can also be used to remove So2 and Nox from coal flue gas and for sterilizing medical devices. EB has a great advantage which includes simultaneous removal of So2 and Nox and the by-product can be used as a fertilizer. The sterilization by Electron Beam is expected to be an alternative to gas sterilization which has some safety issues likely to be discussed in the future projects. (J.P.N.)

  14. Overview of Alternative Bunching and Current-shaping Techniques for Low-Energy Electron Beams

    Energy Technology Data Exchange (ETDEWEB)

    Piot, Philippe [Northern Illinois U.

    2015-12-01

    Techniques to bunch or shape an electron beam at low energies (E <15 MeV) have important implications toward the realization of table-top radiation sources [1] or to the design of compact multi-user free-electron lasers[2]. This paper provides an overview of alternative methods recently developed including techniques such as wakefield-based bunching, space-charge-driven microbunching via wave-breaking [3], ab-initio shaping of the electron-emission process [4], and phase space exchangers. Practical applications of some of these methods to foreseen free-electron-laser configurations are also briefly discussed [5].

  15. Longitudinal beam profiles affected by the current ripples of bending magnets in HIMAC synchrotron

    International Nuclear Information System (INIS)

    The relation between the longitudinal-emittance growth and the noise profiles of the power supply for the bending-magnets was studied to avoid the particle losses from the bucket during the several-minutes circulation. In order to investigate the effect of the actual noise ripples of the power supply, as well as monochromatic noise near to the synchrotron-oscillation frequency, on the temporal evolution of the longitudinal emittance, the beam distribution on the longitudinal phase space was simulated using the tracking method. We found that the longitudinal emittance was increasing with time owing to the series of the noise spectrum, not to the monochromatic noise. (author)

  16. Optimization of a low-pressure hollow-anode electrical discharge for generation of high-current electron beams

    International Nuclear Information System (INIS)

    We report results on the optimization of the design of a high-current hollow-anode (HA) electrical discharge electron beam source that is triggered by a ferroelectric surface discharge. For the ferroelectric sample, we used a BaTi solid solution with a large dielectric constant (ε ∼ 1600). Three different electric schemes for ignition and sustainment of the HA discharge were investigated. The studied HA designs allow reliable ignition and sustainment of the discharge with current amplitude of up to 1.2 kA and pulse duration of up to 2x10-5 s, with and without gas flooding. It was found that the rise time of the discharge current monotonically decreases from ∼10-7.5 μs with the increase of the background pressure from 4x10-5 to 7x10-5 Torr. Generation of high-current electron beams was demonstrated under an accelerating voltage of up to 300 kV and ∼400 ns pulse duration. It was shown that the use of an optimal resistor which supplies an auto-bias potential to the HA output grid eliminates almost entirely the plasma pre-filling of the accelerating gap prior to the application of the accelerating pulse. In addition, it was found that within a certain range of time delays (12.5-15.5 μs) of the application of the accelerating pulse with respect to the beginning of the HA discharge, the amplitude of the diode current remains practically unchanged in spite of a considerable decrease in the amplitude of the discharge current

  17. Optimization of a low-pressure hollow anode electrical discharge for generation of high-current electron beams

    International Nuclear Information System (INIS)

    Full Text:We report results on the optimization of the design of a high-current hollow anode electrical discharge electron beam source triggered by a ferroelectric surface discharge. For the ferroelectric sample we used a BaTi solid solution with a large dielectric constant epsilon =: 1600. Three different electric schemes for ignition and sustaining of the hollow anode discharge were investigated. The studied hollow anode designs allow reliable ignition and sustaining of the discharge with current amplitude of up to 1.2 kA and pulse duration of up to 20 Vs, with and without gas flooding. It was found that the rise time of the discharge current monotonically decreases from N 10 vs to N 7.5 vs with the increase of the background pressure from 4 Pa to 7 Pa. Generation of high-current electron beams was demonstrated under an accelerating voltage of up to 300 kV and N 400 ns pulse duration. It was shown that the use of an optimal resistor which supplies an auto-bias potential to the hollow-anode output grid eliminates almost entirely the plasma pre-filling of the accelerating gap prior to the application of the accelerating pulse. In addition, it was found that within a certain range of time delays (12.5 vμs - 15.5 vμs) of the application of the accelerating pulse with respect to the beginning of the hollow anode discharge, the amplitude of the diode current remains practically unchanged in spite of a considerable decrease in the amplitude of the discharge current

  18. Minimum beam-energy spread of a high-current rf linac

    International Nuclear Information System (INIS)

    Energy spread is an important parameter of an electron linac and, usually, is determined by the time dependence of the external rf accelerating field. By using a combination of fundamental and higher harmonic frequencies, the accelerating field can be maintained approximately constant over a beam bunch with the resultant energy spread approximately zero. This technique is no longer adequate when the longitudinal wake field of the beam bunch is taken into account. The wake-field variation along the bunch length introduces an energy spread that cannot be exactly compensated for with the use of fundamental and higher harmonic frequencies. The achievable minimum energy spread including the wake-field effect is therefore limited. In this paper, the authors report the minimum energy spreads achievable using the fundamental and third-harmonic frequencies, calculated using a least-squares algorithm, for some typical structures in use at Los Alamos National Laboratory. The dependence of these results on bunch shape, bunch charge, and structure frequency is discussed. Also included are discussions of schemes for implementing the third-harmonic frequency and their effectiveness

  19. Application of magnetically insulated transmission lines for high current, high voltage electron beam accelerators

    International Nuclear Information System (INIS)

    Self Magnetically Insulated Transmission Lines (MITL) adders have been used successfully in a number of Sandia accelerators such as HELIA, HERMES III, and SABRE. Most recently the authors used a MITL adder in the RADLAC/SMILE electron beam accelerator to produce high quality, small radius (rb < 2 cm), 11 to 15 MeV, 50 to 100-kA beams with a small transverse velocity v perpendicular/c = β perpendicular ≤ 0.1. In RADLAC/SMILE, a coaxial MITL passed through the eight, 2 MV vacuum envelopes. The MITL summed the voltages of all eight feeds to a single foilless diode. The experimental results are in good agreement with code simulations. The authors' success with the MITL technology led them to investigate the application to higher energy accelerator designs. They have a conceptual design for a cavity-fed MITL that sums the voltages from 100 identical, inductively-isolated cavities. Each cavity is a toroidal structure that is driven simultaneously by four 8-ohm pulse-forming lines, providing a 1-MV voltage pulse to each of the 100 cavities. The point design accelerator is 100 MV, 500 kA, with a 30-50-ns FWHM output pulse

  20. Application of Magnetically Insulated Transmission Lines for high current, high voltage electron beam accelerators

    International Nuclear Information System (INIS)

    Self Magnetically Insulated Transmission Lines (MITL) adders have been used successfully in a number of Sandia accelerators such as HELIA, HERMES III, and SABRE. Most recently we used at MITL adder in the RADLAC/SMILE electron beam accelerator to produce high quality, small radius (rρ < 2 cm), 11 to 15 MeV, 50 to 100-kA beams with a small transverse velocity v perpendicular/c = β perpendicular ≤ 0.1. In RADLAC/SMILE, a coaxial MITL passed through the eight, 2 MV vacuum envelopes. The MITL summed the voltages of all eight feeds to a single foilless diode. The experimental results are in good agreement with code simulations. Our success with the MITL technology led us to investigate the application to higher energy accelerator designs. We have a conceptual design for a cavity-fed MITL that sums the voltages from 100 identical, inductively-isolated cavities. Each cavity is a toroidal structure that is driven simultaneously by four 8-ohm pulse-forming lines, providing a 1-MV voltage pulse to each of the 100 cavities. The point design accelerator is 100 MV, 500 kA, with a 30--50 ns FWHM output pulse. 10 refs

  1. Structural changes in surface layers of the hybrid coatings irradiated by a high current electron beam

    International Nuclear Information System (INIS)

    Full text: By methods SEM, optical microscope, X-ray (XRD) methods of analyses and measurement of microhardness were investigated of powder coatings on a basis (Ni, 24Cr, 4Mo, l-2Si, 1-2B) deposited by a plasma-detonation method with subsequent melting of a surface by electron beams and pulse flows of plasma, and also stainless steel AISI 321 (72Fe, 18Cr, 9Ni, Ti). The structure of samples was investigated using SEM on the device EMB-100B, by method of carbon two-step retorts. Previously surfaces of samples, were ground and polished and on the surface as greeted a relief using chemical etching. Research of phase structure of a coating was investigated using X-ray methods on the device DRON-2. The results of the carried out researches of microstructure of a surface testify to different morphological features of a surface of coatings, under influence of a flow of pulse plasma and electron beam. On the data of a method SEM at 7000 multiple increase on a surface of samples of the steel, 0.1-0.5 microns are visible as is thin granular crystals by the size which on a snapshot are formed units by the size with 2-5 microns, and crystals by the sizes from 1 up to 10 microns. The microhardness of separate sites of a surface of steel, reached up to 2-3·109 Pa

  2. Design of a high-current low-energy beam transport line for an intense D-T/D-D neutron generator

    Science.gov (United States)

    Lu, Xiaolong; Wang, Junrun; Zhang, Yu; Li, Jianyi; Xia, Li; Zhang, Jie; Ding, Yanyan; Jiang, Bing; Huang, Zhiwu; Ma, Zhanwen; Wei, Zheng; Qian, Xiangping; Xu, Dapeng; Lan, Changlin; Yao, Zeen

    2016-03-01

    An intense D-T/D-D neutron generator is currently being developed at the Lanzhou University. The Cockcroft-Walton accelerator, as a part of the neutron generator, will be used to accelerate and transport the high-current low-energy beam from the duoplasmatron ion source to the rotating target. The design of a high-current low-energy beam transport (LEBT) line and the dynamics simulations of the mixed beam were carried out using the TRACK code. The results illustrate that the designed beam line facilitates smooth transportation of a deuteron beam of 40 mA, and the number of undesired ions can be reduced effectively using two apertures.

  3. An annular high-current electron beam with an energy spread in a coaxial magnetically insulated diode

    Science.gov (United States)

    Grishkov, A. A.; Pegel, I. V.

    2013-11-01

    An elementary theory of an annular high-current electron beam in a uniform transport channel and a coaxial magnetically insulated diode is generalized to the case of counterpropagating electron beams with a spread over kinetic energies. Expressions for the sum of the absolute values of the forward and backward currents in a uniform transport channel and for the flux of the longitudinal component of the generalized momentum in a coaxial magnetically insulated diode as functions of the maximum electron kinetic energy are derived for different values of the relative width of the energy distribution function. It is shown that, in a diode with an expanding transport channel and a virtual cathode limiting the extracted current, counterpropagating particle flows are established between the cathode and the virtual cathode within a certain time interval after the beginning of electron emission. The accumulation of electrons in these flows is accompanied by an increase in their spread over kinetic energies and the simultaneous decrease in the maximum kinetic energy. The developed model agrees with the results of particle-in-cell simulations performed using the KARAT and OOPIC-Pro codes.

  4. An annular high-current electron beam with an energy spread in a coaxial magnetically insulated diode

    Energy Technology Data Exchange (ETDEWEB)

    Grishkov, A. A., E-mail: grishkov@to.hcei.tsc.ru; Pegel, I. V. [Russian Academy of Sciences, Institute of High Current Electronics, Siberian Branch (Russian Federation)

    2013-11-15

    An elementary theory of an annular high-current electron beam in a uniform transport channel and a coaxial magnetically insulated diode is generalized to the case of counterpropagating electron beams with a spread over kinetic energies. Expressions for the sum of the absolute values of the forward and backward currents in a uniform transport channel and for the flux of the longitudinal component of the generalized momentum in a coaxial magnetically insulated diode as functions of the maximum electron kinetic energy are derived for different values of the relative width of the energy distribution function. It is shown that, in a diode with an expanding transport channel and a virtual cathode limiting the extracted current, counterpropagating particle flows are established between the cathode and the virtual cathode within a certain time interval after the beginning of electron emission. The accumulation of electrons in these flows is accompanied by an increase in their spread over kinetic energies and the simultaneous decrease in the maximum kinetic energy. The developed model agrees with the results of particle-in-cell simulations performed using the KARAT and OOPIC-Pro codes.

  5. Vircator with premodulation of electron beam on the basis of heavy-current pulse-periodic accelerator

    CERN Document Server

    Kitsanov, S A; Korovin, S D; Kurkan, I K; Pegel, I V; Polevin, S D

    2002-01-01

    One carried out theoretical, numerical and experimental investigations into vircator with premodulation of wavelength decimeter region electron beam. One analyzed possible mechanisms of generation excitation in systems with a virtual cathode. On the basis of numerical experiment results one developed experimental model of two-section vircator without external magnetic field. In experiments with heavy-current pulse-periodic electron accelerator within wavelength decimeter region one produced supermode generation with up to 1 GW power and approx 25 ns duration at approx 5% efficiency of generation. By varying parameters of resonator one managed to ensure continuous retuning of vircator generation frequency within approx 15% band at half level of power

  6. Recent advances in plasma devices based on plasma lens configuration for manipulating high-current heavy ion beams

    International Nuclear Information System (INIS)

    We describe new results of development of novel generation cylindrical plasma devices based on the electrostatic plasma lens configuration and concept of electrons magnetic insulation. The crossed electric and magnetic fields plasma lens configuration provides us with the attractive and suitable method for establishing a stable plasma discharge at low pressure. Using plasma lens configuration in this way some cost-effective plasma devices were developed for ion treatment and deposition of exotic coatings and the effective lens was first proposed for manipulating high-current beams of negatively charged particles. Here we describe operation and features of these plasma devices, and results of theoretical consideration of mechanisms determining their optimal operation conditions.

  7. Vircator with premodulation of electron beam on the basis of heavy-current pulse-periodic accelerator

    International Nuclear Information System (INIS)

    One carried out theoretical, numerical and experimental investigations into vircator with premodulation of wavelength decimeter region electron beam. One analyzed possible mechanisms of generation excitation in systems with a virtual cathode. On the basis of numerical experiment results one developed experimental model of two-section vircator without external magnetic field. In experiments with heavy-current pulse-periodic electron accelerator within wavelength decimeter region one produced supermode generation with up to 1 GW power and ∼ 25 ns duration at ∼ 5% efficiency of generation. By varying parameters of resonator one managed to ensure continuous retuning of vircator generation frequency within ∼ 15% band at half level of power

  8. The influence of guiding magnetic field on beam current and plasma expansion in foil-less diode

    International Nuclear Information System (INIS)

    The impedance collapse phenomenon in planar diodes has been widely investigated and is believed to be induced by the axial plasma expansion. However, there are few studies about the impedance collapse phenomenon in foil-less diodes, which may occur under a low guiding magnetic field and cannot be explained by the axial plasma expansion. This paper tries to explain this phenomenon by constructing a physical model with consideration of the radial expansion of cathode plasmas. Our physical model can quantitatively describe the formation process of beam current in experiments with reasonable parameters, and it demonstrates that a lower guiding magnetic field will lead to a faster radial plasma expansion speed

  9. Metallurgical characterization of pulsed current gas tungsten arc, friction stir and laser beam welded AZ31B magnesium alloy joints

    International Nuclear Information System (INIS)

    This paper reports the influences of welding processes such as friction stir welding (FSW), laser beam welding (LBW) and pulsed current gas tungsten arc welding (PCGTAW) on mechanical and metallurgical properties of AZ31B magnesium alloy. Optical microscopy, scanning electron microscopy, transmission electron microscopy and X-Ray diffraction technique were used to evaluate the metallurgical characteristics of welded joints. LBW joints exhibited superior tensile properties compared to FSW and PCGTAW joints due to the formation of finer grains in weld region, higher fusion zone hardness, the absence of heat affected zone, presence of uniformly distributed finer precipitates in weld region.

  10. Halo Evolution of Hypereutectic Al-17.5Si Alloy Treated with High-Current Pulsed Electron Beam

    OpenAIRE

    Hu, L.; Gao, B.; Lv, J. K.; Sun, S. C.; Hao, Y.; Tu, G. F.

    2015-01-01

    Halo evolution of an Al-17.5Si alloy surface after treatment with increasing pulse numbers of a high-current pulsed electron beam (HCPEB) was investigated. A halo is a ring microstructure resembling a bull’s eye. SEM results indicate that the nanocrystallization of halo induced by HCPEB treatment leads to gradual diffusion of the Si phase. Multiple pulses numbers cause the Si phase to be significantly refined and uniformly distributed. In addition, nanosilicon particles with a grain size of 3...

  11. Current-driven ion-acoustic and potential-relaxation instabilities excited in plasma plume during electron beam welding

    Energy Technology Data Exchange (ETDEWEB)

    Trushnikov, D. N., E-mail: trdimitr@yandex.ru [The department for Applied Physics, Perm National Research Polytechnic University, Perm, 614990 (Russian Federation); Mladenov, G. M., E-mail: gmmladenov@abv.bg; Koleva, E. G., E-mail: eligeorg@abv.bg [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tzarigradsko Shose, 1784, Sofia (Bulgaria); Technology Centre of Electron Beam and Plasma Technologies and Techniques, 68-70 Vrania, ap.10, Banishora,1309, Sofia (Bulgaria); Belenkiy, V. Ya., E-mail: mtf@pstu.ru; Varushkin, S. V., E-mail: stepan.varushkin@mail.ru [The department for Welding Production and Technology of Constructional Materials, Perm National Research Polytechnic University, Perm, 614990 (Russian Federation)

    2014-04-15

    Many papers have sought correlations between the parameters of secondary particles generated above the beam/work piece interaction zone, dynamics of processes in the keyhole, and technological processes. Low- and high-frequency oscillations of the current, collected by plasma have been observed above the welding zone during electron beam welding. Low-frequency oscillations of secondary signals are related to capillary instabilities of the keyhole, however; the physical mechanisms responsible for the high-frequency oscillations (>10 kHz) of the collected current are not fully understood. This paper shows that peak frequencies in the spectra of the collected high-frequency signal are dependent on the reciprocal distance between the welding zone and collector electrode. From the relationship between current harmonics frequency and distance of the collector/welding zone, it can be estimated that the draft velocity of electrons or phase velocity of excited waves is about 1600 m/s. The dispersion relation with the properties of ion-acoustic waves is related to electron temperature 10 000 K, ion temperature 2 400 K and plasma density 10{sup 16} m{sup −3}, which is analogues to the parameters of potential-relaxation instabilities, observed in similar conditions. The estimated critical density of the transported current for creating the anomalous resistance state of plasma is of the order of 3 A·m{sup −2}, i.e. 8 mA for a 3–10 cm{sup 2} collector electrode. Thus, it is assumed that the observed high-frequency oscillations of the current collected by the positive collector electrode are caused by relaxation processes in the plasma plume above the welding zone, and not a direct demonstration of oscillations in the keyhole.

  12. The application of heavily damped superconducting cavities to the acceleration of high current electron beams

    International Nuclear Information System (INIS)

    In order to achieve the high luminosities required for a B-factory, the average currents required in the two rings are 1 ampere for the high energy ring and 2 amperes for the low energy ring. With such high currents the impedances of the rings must be very low. The reasons will be given for choosing superconducting RF cavities for this purpose and the methods used to obtain the required damping of the higher order modes will also be described. Prototype 1/3 scale and full scale superconducting cavities have been built and tested and the results of these tests are given. (Author) 5 figs., 12 refs

  13. New methods for high current fast ion beam production by laser-driven acceleration

    Czech Academy of Sciences Publication Activity Database

    Margarone, Daniele; Krása, Josef; Prokůpek, Jan; Velyhan, Andriy; Torrisi, L.; Picciotto, A.; Giuffrida, L.; Gammino, S.; Cirrone, P.; Cutroneo, M.; Romano, F.; Serra, E.; Mangione, A.; Rosinski, M.; Parys, P.; Ryc, L.; Limpouch, J.; Láska, Leoš; Jungwirth, Karel; Ullschmied, Jiří; Mocek, Tomáš; Korn, Georg; Rus, Bedřich

    2012-01-01

    Roč. 83, č. 2 (2012), "02B307-1"-"02B307-3". ISSN 0034-6748 R&D Projects: GA ČR(CZ) GAP205/11/1165; GA MŠk(CZ) LC528; GA MŠk ED1.1.00/02.0061; GA MŠk EE.2.3.20.0087; GA MŠk ED2.1.00/01.0027 Grant ostatní: ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061; OP VK 2 LaserGen(XE) CZ.1.07/2.3.00/20.0087; HILASE(XE) CZ.1.05/2.1.00/01.0027 Institutional research plan: CEZ:AV0Z10100523; CEZ:AV0Z20430508 Keywords : ion beam * laser-driven acceleration Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.602, year: 2012 http://dx.doi.org/10.1063/1.3669796

  14. Numerical analysis of the morphological and phase changes in the TiN/Al2O3 coating under high current electron beam modification

    Directory of Open Access Journals (Sweden)

    A.D. Pogrebnjak

    2013-01-01

    Full Text Available The modification of the surface structure of the hybrid coating TiN/Al2O3 with a low-energy high-current electron beam (NCEB is performed. The surface roughness is considered as a function of beam current. Surfaces of the obtained samples are investigated within the two-dimensional multifractal detrended fluctuation analysis (MF-DFA. The multifractal spectrum of the surface is calculated as a quantitative parameter of the roughness. It is shown that with the increase of the beam energy, the surface become more regular and uniform.

  15. Numerical analysis of the morphological and phase changes in the TiN/Al_{2}O_{3} coating under high current electron beam modification

    OpenAIRE

    A.D. Pogrebnjak; V.N. Borisyuk; A.A. Bagdasaryan

    2013-01-01

    The modification of the surface structure of the hybrid coating TiN/Al2O3 with a low-energy high-current electron beam (NCEB) is performed. The surface roughness is considered as a function of beam current. Surfaces of the obtained samples are investigated within the two-dimensional multifractal detrended fluctuation analysis (MF-DFA). The multifractal spectrum of the surface is calculated as a quantitative parameter of the roughness. It is shown that with the increase of the beam energy, the...

  16. Theory of current-drive in plasmas

    International Nuclear Information System (INIS)

    The continuous operation of a tokamak fusion reactor requires, among other things, a means of providing continuous toroidal current. Such operation is preferred to the conventional pulsed operation, where the plasma current is induced by a time-varying magnetic field. A variety of methods has been proposed to provide continuous current, including methods which utilize particle beams or radio frequency waves in any of several frequency regimes. Currents as large as half a mega-amp have now been produced in the laboratory by such means, and experimentation in these techniques has now involved major tokamak facilities worldwide

  17. Development of a low-energy and high-current pulsed neutral beam injector with a washer-gun plasma source for high-beta plasma experiments.

    Science.gov (United States)

    Ii, Toru; Gi, Keii; Umezawa, Toshiyuki; Asai, Tomohiko; Inomoto, Michiaki; Ono, Yasushi

    2012-08-01

    We have developed a novel and economical neutral-beam injection system by employing a washer-gun plasma source. It provides a low-cost and maintenance-free ion beam, thus eliminating the need for the filaments and water-cooling systems employed conventionally. In our primary experiments, the washer gun produced a source plasma with an electron temperature of approximately 5 eV and an electron density of 5 × 10(17) m(-3), i.e., conditions suitable for ion-beam extraction. The dependence of the extracted beam current on the acceleration voltage is consistent with space-charge current limitation, because the observed current density is almost proportional to the 3/2 power of the acceleration voltage below approximately 8 kV. By optimizing plasma formation, we successfully achieved beam extraction of up to 40 A at 15 kV and a pulse length in excess of 0.25 ms. Its low-voltage and high-current pulsed-beam properties enable us to apply this high-power neutral beam injection into a high-beta compact torus plasma characterized by a low magnetic field. PMID:22938291

  18. Studies and optimization of Pohang Light Source-II superconducting radio frequency system at stable top-up operation with beam current of 400 mA

    International Nuclear Information System (INIS)

    After three years of upgrading work, the Pohang Light Source-II (PLS-II) is now successfully operating. The final quantitative goal of PLS-II is a top-up user-service operation with beam current of 400 mA to be completed by the end of 2014. During the beam store test up to 400 mA in the storage ring (SR), it was observed that the vacuum pressure around the radio frequency (RF) window of the superconducting cavity rapidly increases over the interlock level limiting the availability of the maximum beam current storing. Although available beam current is enhanced by setting a higher RF accelerating voltage, it is better to keep the RF accelerating voltage as low as possible in the long time top-up operation. We investigated the cause of the window vacuum pressure increment by studying the changes in the electric field distribution at the superconducting cavity and waveguide according to the beam current. In our simulation, an equivalent physical modeling was developed using a finite-difference time-domain code. The simulation revealed that the electric field amplitude at the RF window is exponentially increased as the beam current increases, thus this high electric field amplitude causes a RF breakdown at the RF window, which comes with the rapid increase of window vacuum pressure. The RF accelerating voltage of PLS-II RF system was set to 4.95 MV, which was estimated using the maximum available beam current that works as a function of RF voltage, and the top-up operation test with the beam current of 400 mA was successfully carried out

  19. Transition from Beam-Target to Thermonuclear Fusion in High-Current Deuterium Z -Pinch Simulations

    Science.gov (United States)

    Offermann, Dustin T.; Welch, Dale R.; Rose, Dave V.; Thoma, Carsten; Clark, Robert E.; Mostrom, Chris B.; Schmidt, Andrea E. W.; Link, Anthony J.

    2016-05-01

    Fusion yields from dense, Z -pinch plasmas are known to scale with the drive current, which is favorable for many potential applications. Decades of experimental studies, however, show an unexplained drop in yield for currents above a few mega-ampere (MA). In this work, simulations of DD Z -Pinch plasmas have been performed in 1D and 2D for a constant pinch time and initial radius using the code Lsp, and observations of a shift in scaling are presented. The results show that yields below 3 MA are enhanced relative to pure thermonuclear scaling by beamlike particles accelerated in the Rayleigh-Taylor induced electric fields, while yields above 3 MA are reduced because of energy lost by the instability and the inability of the beamlike ions to enter the pinch region.

  20. Control electron beam oscillation regimes in Pierce diode with overcritical current

    International Nuclear Information System (INIS)

    The effect of the delayed feedback on the complex oscillation regimes in the electron flux with the overcritical current in the Pierce diode is studied. The possibility of controlling the oscillation regimes through changing the feedback parameters is shown. The finite-dimensional model, describing the behavior of the electron flux in the Pierce diode hydrodynamic model, is constructed. Its behavior under the effect of the delayed feedback is studied

  1. Coherent radiation from high-current electron beams of linear accelerators and its applications

    Science.gov (United States)

    Okuda, Shuichi; Takanaka, Makoto; Nakamura, Mitsumi; Kato, Ryukou; Takahashi, Toshiharu; Nam, Soon-Kwon; Taniguchi, Ryouichi; Kojima, Takao

    2006-08-01

    The characteristics of the far-infrared light source using the coherent radiation emitted from a high-energy short electron bunch have been investigated. The coherent radiation has a continuous spectrum in a submillimeter to millimeter wavelength range and the brightness is relatively high. The spectrum of the radiation is determined by the longitudinal form factor of the electron bunch. The operational conditions of a high-current linear accelerator have been optimized using an electron bunch shape monitor. The coherent transition radiation light source has been applied to absorption spectroscopy for liquid water and to an imaging experiment for a leaf of rose.

  2. Development of an all-permanent-magnet microwave ion source equipped with multicusp magnetic fields for high current proton beam production.

    Science.gov (United States)

    Tanaka, M; Hara, S; Seki, T; Iga, T

    2008-02-01

    An all-permanent-magnet (APM) microwave hydrogen ion source was developed to reduce the size and to simplify structure of a conventional solenoid coil microwave ion source developed for reliability improvement of high current proton linac application systems. The difficulty in developing the APM source was sensitive dependence of the source performance on axial magnetic field in the microwave discharge chamber. It was difficult to produce high current proton beam stably without precise tuning of the magnetic field using solenoid coils. We lowered the sensitivity using multicusp magnetic fields for plasma confinement at the discharge chamber sidewall of the source. This enabled stable high current proton beam production with the APM microwave ion source with no tuning coil. The water cooling and the power supply for the coils are not necessary for the APM source, which leads to better reliability and system simplification. The outer diameter of the APM source was around 300 mm, which was 20% lower than the coil source. The APM source produced a maximum hydrogen ion beam current of 65 mA (high current density of 330 mA/cm(2), proton ratio of 87%, and beam energy of 30 keV) with a 5 mm diameter extraction aperture, pulse width of 400 micros, and 20 Hz repetition rate at 1.3 kW microwave power. This performance is almost the same as the best performances of the conventional coil sources. The extracted ion beams were focused with electrostatic five-grid lens to match beam to acceptance of radio-frequency quadrupole linacs. The maximum focused beam current through the orifice (5 mm radius) and the lens was 36 mA and the 90% focused beam half-width was 1-2 mm. PMID:18315183

  3. High current density pulsed cathode experiments at SLAC

    International Nuclear Information System (INIS)

    A 1.9 microperveance beam diode has been constructed to test high current density cathodes for use in klystrons. Several standard and specially coated dispenser cathodes are being tested. Results of tests to date show average cathode current densities in excess of 25 amps/cm, and maximum electric field gradients of more than 450 kV/cm for pulses of the order of 1μsec. 3 refs., 11 figs

  4. MEK Inhibitors Reverse cAMP-Mediated Anxiety in Zebrafish

    DEFF Research Database (Denmark)

    Lundegaard, Pia R.; Anastasaki, Corina; Grant, Nicola J.;

    2015-01-01

    adult zebrafish, while causing no anxiolytic behavioral effects on their own. The mechanism underlying cAMP-induced anxiety is via crosstalk to activation of the RAS-MAPK signaling pathway. We propose that targeting crosstalk signaling pathways can be an effective strategy for mental health disorders......Altered phosphodiesterase (PDE)-cyclic AMP (cAMP) activity is frequently associated with anxiety disorders, but current therapies act by reducing neuronal excitability rather than targeting PDE-cAMP-mediated signaling pathways. Here, we report the novel repositioning of anti-cancer MEK inhibitors...... as anxiolytics in a zebrafish model of anxiety-like behaviors. PDE inhibitors or activators of adenylate cyclase cause behaviors consistent with anxiety in larvae and adult zebrafish. Small-molecule screening identifies MEK inhibitors as potent suppressors of cAMP anxiety behaviors in both larvae and...

  5. Precision measurement of the cross section of charged-current and neutral current processes at large Q2 at HERA with the polarized-electron beam

    International Nuclear Information System (INIS)

    The inclusive cross sections for both charged and neutral current processes have been measured in interactions of longitudinally polarized electrons (positrons) with unpolarized protons using the full data samples collected by H1 at HERA-II. The data taken at a center-of-mass energy of 319 GeV correspond to an integrated luminosity of 149.1 pb-1 and 180.0 pb-1 for e-p and e+p collisions, representing an increase in statistics of a factor of 10 and 2, respectively, over the data from HERA-I. The measured double differential cross sections d2σ/dxdQ2 cover more than two orders of magnitude in both Q2, the negative four-momentum transfer squared, up to 30000 GeV2, and Bjorken x, down to 0.003. The cross section data are compared to predictions of the Standard Model which is able to provide a good description of the data. The polarization asymmetry as a function of Q2 is measured with improved precision, confirming the previous observation of P violation effect in neutral current ep scattering at distances down to 10-18 m. The total cross sections of the charged current process, for Q2 > 400 GeV2 and inelasticity y ± beams and different polarization values. Together with the corresponding cross section obtained from the previously published unpolarized data, the polarization dependence of the charged current cross section is measured and found to be in agreement with the Standard Model prediction with the absence of right-handed charged current. The cross sections are combined with previously published data from H1 to obtain the most precise unpolarized measurements. These are used to extract the structure function xF3γZ which is sensitive to the valence quark distributions down to low x values. The new cross sections have also been used in a combined electroweak and QCD fit to significantly improve the light quark couplings to the Z-boson than those obtained based on the HERA-I data alone. (orig.)

  6. Measurement of charged current deep inelastic scattering cross sections with a longitudinally polarised electron beam at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, IL (US)] (and others)

    2008-12-15

    Measurements of the cross sections for charged current deep inelastic scattering in e{sup -}p collisions with longitudinally polarised electron beams are presented. The measurements are based on a data sample with an integrated luminosity of 175 pb{sup -1} collected with the ZEUS detector at HERA at a centre-of-mass energy of 318 GeV. The total cross section is given for positively and negatively polarised electron beams. The differential cross-sections d{sigma}/dQ{sup 2}, d{sigma}/dx and d{sigma}/dy are presented for Q{sup 2}>200 GeV{sup 2}. The double-differential cross-section d{sup 2}{sigma}/dxdQ{sup 2} is presented in the kinematic range 280

  7. X-ray framing camera for pulsed, high current, electron beam x-ray sources

    CERN Document Server

    Failor, B H; Riordan, j c; Lojewski, D Y

    2007-01-01

    High power x-ray sources built for nuclear weapons effects testing are evolving toward larger overall diameters and smaller anode cathode gaps. We describe a framing camera developed to measure the time-evolution of these 20-50 ns pulsed x-ray sources produced by currents in the 1.5-2.5 MA range and endpoint voltages between 0.2 and 1.5 MV. The camera has up to 4 frames with 5 ns gate widths; the frames are separated by 5 ns. The image data are recorded electronically with a gated intensified CCD camera and the data are available immediately following a shot. A fast plastic scintillator (2.1 ns decay time) converts the x-rays to visible light and, for high sensitivity, a fiber optic imaging bundle carries the light to the CCD input. Examples of image data are shown.

  8. Warmer amps for the LHC

    CERN Multimedia

    Anaïs Schaeffer

    2012-01-01

    CERN is working together with an Italian company to develop superconducting cables that can function at temperatures of up to 25 K (-248°C). This will make it possible to move LHC magnet power supplies out of the tunnel, protecting them from exposure to the showers of very high-energy particles produced by the accelerator.   Figure 1: devices of this type, which measure approximately 10 metres in length, are inserted between the accelerating magnets at different points along the LHC. When it comes to consuming electricity, the magnets that steer particles through large accelerators can be characterised with just one word: greedy. For the LHC, the total current can reach 1.5 million amps. At the present time, this current is brought in via copper cables of up to 10 cm in diameter. In the tunnel, these cables connect the current leads - which provide the transition between the ambient-temperature cables and the magnets in their bath of superfluid helium - to the power supply. In the a...

  9. Controlling Charge and Current Neutralization of an Ion Beam Pulse in a Background Plasma by Application of a Solenoidal Magnetic Field I: Weak Magnetic Field Limit

    Energy Technology Data Exchange (ETDEWEB)

    Kaganovich, I. D., Startsev, E. A., Sefkow, A. B., Davidson, R. C.

    2008-10-10

    Propagation of an intense charged particle beam pulse through a background plasma is a common problem in astrophysics and plasma applications. The plasma can effectively neutralize the charge and current of the beam pulse, and thus provides a convenient medium for beam transport. The application of a small solenoidal magnetic field can drastically change the self-magnetic and self- electric fields of the beam pulse, thus allowing effective control of the beam transport through the background plasma. An analytic model is developed to describe the self-magnetic field of a finite- length ion beam pulse propagating in a cold background plasma in a solenoidal magnetic field. The analytic studies show that the solenoidal magnetic field starts to infuence the self-electric and self-magnetic fields when ωce > ωpeβb, where ωce = eβ/mec is the electron gyrofrequency, ωpe is the electron plasma frequency, and βb = Vb/c is the ion beam velocity relative to the speed of light. This condition typically holds for relatively small magnetic fields (about 100G). Analytical formulas are derived for the effective radial force acting on the beam ions, which can be used to minimize beam pinching. The results of analytic theory have been verified by comparison with the simulation results obtained from two particle-in-cell codes, which show good agreement.

  10. Measurement of Neutral Current Neutral Pion Production on Carbon in a Few-GeV Neutrino Beam

    Energy Technology Data Exchange (ETDEWEB)

    Kurimoto, Yoshinori [Kyoto Univ. (Japan)

    2010-01-01

    Understanding of the π0 production via neutrino-nucleus neutral current interaction in the neutrino energy region of a few GeV is essential for the neutrino oscillation experiments. In this thesis, we present a study of neutral current π0 production from muon neutrinos scattering on a polystyrene (C8H8) target in the SciBooNE experiment. All neutrino beam data corresponding to 0.99 × 1020 protons on target have been analyzed. We have measured the cross section ratio of the neutral current π0 production to the total charge current interaction and the π0 kinematic distribution such as momentum and direction. We obtain [7.7 ± 0.5(stat.) ± 0.5(sys.)] × 10-2 as the ratio of the neutral current neutral pion production to total charged current cross section; the mean energy of neutrinos producing detected neutral pions is 1.1 GeV. The result agrees with the Rein- Sehgal model, which is generally used for the Monte Carlo simulation by many neutrino oscillation experiments. We achieve less than 10 % uncertainty which is required for the next generation search for νµ → νe oscillation. The spectrum shape of the π0 momentum and the distribution of the π0 emitted angle agree with the prediction, which means that not only the Rein-Sehgal model but also the intra-nuclear interaction models describe our data well. We also measure the ratio of the neutral current coherent pion production to total charged current cross section to be (1.17 ± 0.23 ) × 10-2 based on the Rein and Sehgal model. The result gives the evidence for non-zero coherent pion production via neutral current interaction at the mean neutrino energy of 1.0 GeV.

  11. Laser-beam-induced current mapping evaluation of porous silicon-based passivation in polycrystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Rabha, M. Ben; Bessais, B. [Laboratoire de Nanomateriaux et des Systemes pour l' Energie, Centre de Recherches et des Technologies de l' Energie - Technopole de Borj-Cedria BP 95, 2050 Hammam-Lif (Tunisia); Dimassi, W.; Bouaicha, M.; Ezzaouia, H. [Laboratoire de photovoltaique, des semiconducteurs et des nanostructures, Centre de Recherches et des Technologies de l' Energie - Technopole de Borj-Cedria BP 95, 2050 Hammam-Lif (Tunisia)

    2009-05-15

    In the present work, we report on the effect of introducing a superficial porous silicon (PS) layer on the performance of polycrystalline silicon (pc-Si) solar cells. Laser-beam-induced current (LBIC) mapping shows that the PS treatment on the emitter of pc-Si solar cells improves their quantum response and reduce the grain boundaries (GBs) activity. After the porous silicon treatment, mapping investigation shows an enhancement of the LBIC and the internal quantum efficiency (IQE), due to an improvement of the minority carrier diffusion length and the passivation of recombination centers at the GBs as compared to the reference substrate. It was quantitatively shown that porous silicon treatment can passivate both the grains and GBs. (author)

  12. Numerical simulation of thermal-mechanical process of Al-Si-Pb alloy treated by high current pulsed electron beam

    Institute of Scientific and Technical Information of China (English)

    L(U) Xiao-xia; LI Rong-guang; AN Jian

    2006-01-01

    The modified microstructure of Al-Si-Pb alloys irradiated by high current electron beam (HCPEB) reveals three distinct regions: a molten zone, an overlapped zone of heat-affected and quasistatic thermal stress-affected zone, and a transition zone followed by the substrate. The hardness and wear properties of the alloys were significantly improved. To better understand these changes in microstructure and properties, the physical model for the simulation of temperature and quasistatic stress fields was established. Based on experimental investigation and physical models, the temperature field and stress field were simulated for Al-Si-Pb alloy. The starting melting position, largest crater depth, melting layer thickness, and quasistatic stress distribution were obtained. These results reveal the mechanism of crater formation on the surface and improvement of hardness and wear resistance.

  13. Imaging interfacial electrical transport in graphene-MoS2 heterostructures with electron-beam-induced-currents

    Science.gov (United States)

    White, E. R.; Kerelsky, Alexander; Hubbard, William A.; Dhall, Rohan; Cronin, Stephen B.; Mecklenburg, Matthew; Regan, B. C.

    2015-11-01

    Heterostructure devices with specific and extraordinary properties can be fabricated by stacking two-dimensional crystals. Cleanliness at the inter-crystal interfaces within a heterostructure is crucial for maximizing device performance. However, because these interfaces are buried, characterizing their impact on device function is challenging. Here, we show that electron-beam induced current (EBIC) mapping can be used to image interfacial contamination and to characterize the quality of buried heterostructure interfaces with nanometer-scale spatial resolution. We applied EBIC and photocurrent imaging to map photo-sensitive graphene-MoS2 heterostructures. The EBIC maps, together with concurrently acquired scanning transmission electron microscopy images, reveal how a device's photocurrent collection efficiency is adversely affected by nanoscale debris invisible to optical-resolution photocurrent mapping.

  14. Total neutrino and antineutrino charged current cross section measurements in 100, 160, and 200 GeV narrow band beams

    International Nuclear Information System (INIS)

    Neutrino and antineutrino total charged current cross sections on iron were measured in the 100, 160, and 200 GeV narrow band beams at the CERN SPS in the energy range 10 to 200 GeV. Assuming σ/E to be constant, the values corrected for non-isoscalarity are σν/E=(0.686 ±0.019)x10-38 cm2/(GeV . nucleon) and σν/E=(0.339±0.010)x10-38 cm2/(GeV . nucleon). Between 50 and 150 GeV no energy dependence of σ/E was observed within ±3% for neutrino and ±4% for antineutrino interactions. (orig.)

  15. Imaging interfacial electrical transport in graphene–MoS{sub 2} heterostructures with electron-beam-induced-currents

    Energy Technology Data Exchange (ETDEWEB)

    White, E. R., E-mail: ewhite@physics.ucla.edu; Kerelsky, Alexander; Hubbard, William A.; Regan, B. C., E-mail: regan@physics.ucla.edu [Department of Physics and Astronomy and California NanoSystems Institute, University of California, Los Angeles, California 90095 (United States); Dhall, Rohan; Cronin, Stephen B. [Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089 (United States); Mecklenburg, Matthew [Center for Electron Microscopy and Microanalysis, University of Southern California, Los Angeles, California 90089 (United States)

    2015-11-30

    Heterostructure devices with specific and extraordinary properties can be fabricated by stacking two-dimensional crystals. Cleanliness at the inter-crystal interfaces within a heterostructure is crucial for maximizing device performance. However, because these interfaces are buried, characterizing their impact on device function is challenging. Here, we show that electron-beam induced current (EBIC) mapping can be used to image interfacial contamination and to characterize the quality of buried heterostructure interfaces with nanometer-scale spatial resolution. We applied EBIC and photocurrent imaging to map photo-sensitive graphene-MoS{sub 2} heterostructures. The EBIC maps, together with concurrently acquired scanning transmission electron microscopy images, reveal how a device's photocurrent collection efficiency is adversely affected by nanoscale debris invisible to optical-resolution photocurrent mapping.

  16. Improvement of Wear Resistance of Magnesium Alloy AZ91HP by High Current Pulsed Electron Beam Treatment

    Institute of Scientific and Technical Information of China (English)

    GAO Bo; HAO Sheng-zhi; ZOU Jian-xin; JIANG Li-min; ZHOU Ji-yang; DONG Chuang

    2004-01-01

    Surface modification of magnesium alloy AZ91HP (9wt%Al, 0.5wt%Zn, 0.5wt%Mn, Mg remaining percentage) by high current pulsed electron beam (HCPEB) treatment was studied in this paper. The secondary phase Mg17Al12 is nearly completely dissolved and as a result, a super-saturated solid solution forms on the re-melted surface.The microhardness is increased both in and far beyond the heat-affected zone (HAZ), reaching about 250μm.Measurements on sliding wear have shown that the wear resistance of the treated samples was improved by a factor of about 2.4 as compared to the as-received sample. It is also found that the sliding wear resistance can be further improved by surface alloying with TiN.

  17. Improved Corrosion Resistance of Magnesium Alloys AZ31 and AZ91HP by High Current Pulsed Electron Beam Treatment

    Institute of Scientific and Technical Information of China (English)

    HAO Sheng- zhi; GAO Bo; ZHOU Ji-yang; DONG Chuang

    2004-01-01

    Surface treatment of magnesium alloys AZ31 and AZ91HP by a high current pulsed electron beam (HCPEB)was investigated in the present paper. The corrosion resistance of treated samples was tested in a 5% (wt%) NaCl solution,showing remarkably improvement as manifested by polarization curves. According to EPMA analysis, the intermetallic Mg17Al12 in the surface layer of AZ91HP sample almost disappeared after the treatment of HCPEB, leaving the surface layer in a state of supersaturated solid solution. Both the augmentation of aluminum content and the formation of supersaturated structure in the surface layer are believed to contribute to the improved corrosion resistance of AZ31 and AZ91HP.

  18. Improved Corrosion Resistance of Magnesium Alloys AZ31 and AZ91HP by High Current Pulsed Electron Beam Treatment

    Institute of Scientific and Technical Information of China (English)

    HAOSheng-zhi; GAOBo; ZHOUJi-yang; DONGChuang

    2004-01-01

    Surface treatment of magnesium alloys AZ31 and AZ91HP by a high current pulsed electron beam (HCPEB) was investigated in the present paper. The corrosion resistance of treated samples was tested in a 5% (wt%) NaCl solution, showing remarkably improvement as manifested by polarization curves. According to EPMA analysis, the intermetallic Mg17Al12 in the surface layer of AZ91HP sample almost disappeared after the treatment of HCPEB, leaving the surface layer in a state of supersaturated solid solution. Both the augmentation of aluminum content and the formation of supersaturated structure in the surface layer are believed to contribute to the improved corrosion resistance of AZ31 and AZ91HP.

  19. A direct-current pion focusing magnet for low energy in-flight muon-neutrino beams

    International Nuclear Information System (INIS)

    A cylindrically-symmetric, direct-current magnet has been designed for use in the focusing of pions to improve the muon-neutrino flux obtained from decays in-flight at low energy accelerators. The device uses conventional magnet technology with specially designed field-shaping windings to achieve optimized focusing for positive pions and defocusing for negative pions. A prototype magnet has been constructed and its magnetic field map used in a ray tracing program from which it has been calculated that a factor of four improvement in the neutrino flux at a downstream detector can be realized when compared to an unfocused pion source. The design approach taken in this paper to select the appropriate coil distribution to optimize focusing may be applicable in other types of particle beam lines as well as in high energy collider detectors where toroidal magnet geometries have been proposed. (orig.)

  20. Current-induced spin polarization in transition metals and Bi/Ag bilayers observed by spin-polarized positron beam

    Science.gov (United States)

    Zhang, Hongjun; Yamamoto, Shunya; Fukaya, Yuki; Maekawa, Masaki; Li, Hui; Kawasuso, Atsuo; Seki, Takeshi; Saitoh, Eiji; Takanashi, Koki; JAEA Team; Tohoku Team

    2015-03-01

    Current-induced spin polarization (CISP) on the outermost surfaces of Au, Cu, Pt, Pd, Ta, and W films were studied by spin-polarized positron beam (SPPB). The Au and Cu surfaces showed no significant CISP. In contrast, the Pt, Pd, Ta, and W films exhibited large CISP (3 ~ 15% per charge current of 105 A/cm2) and the CISP of Ta and W were opposite to those of Pt and Pd. The sign of the CISP obeys the same rule in spin Hall effect suggesting that the spin-orbit coupling is mainly responsible for the CISP. The outermost spin poalrization of Bi/Ag/Al2O3andAg/Bi/Al2O3 (charge currents directly connected to Ag layers) were probed by SPPB. The opposite outermost spin polarization of Bi/Ag/Al2O3andAg/Bi/Al2O3 clarified the charge-to-spin conversion in Bi/Ag bilayers. Nevertheless, the magnitudes of the outermost spin polarization of Bi(0.3 ~5)/Ag(25)/Al2O3 (numbers in parentheses denote thickness in nm) and Ag(25 ~500)/Bi(8)/Al2O3 decrease exponentially with increasing Bi thickness and Ag thickness, respectively. This provides probably the first direct evidence for spin diffusion mechanism. Financial support from JSPS Kakenhi Grant 24310072.

  1. Influence of electron-beam lithography exposure current level on the transport characteristics of graphene field effect transistors

    Science.gov (United States)

    Kang, Sangwoo; Movva, Hema C. P.; Sanne, Atresh; Rai, Amritesh; Banerjee, Sanjay K.

    2016-03-01

    Many factors have been identified to influence the electrical transport characteristics of graphene field-effect transistors. In this report, we examine the influence of the exposure current level used during electron beam lithography (EBL) for active region patterning. In the presence of a self-assembled hydrophobic residual layer generated by oxygen plasma etching covering the top surface of the graphene channel, we show that the use of low EBL current level results in higher mobility, lower residual carrier density, and charge neutrality point closer to 0 V, with reduced device-to-device variations. We show that this correlation originates from the resist heating dependent release of radicals from the resist material, near its interface with graphene, and its subsequent trapping by the hydrophobic polymer layer. Using a general model for resist heating, we calculate the difference in resist heating for different EBL current levels. We further corroborate our argument through control experiments, where radicals are either intentionally added or removed by other processes. We also utilize this finding to obtain mobilities in excess of 18 000 cm2/V s on silicon dioxide substrates. We believe these results are applicable to other 2D materials such as transition metal dichalcogenides and nanoscale devices in general.

  2. Radiotherapy of Teikyo University. (1) Experience and the current status at Itabashi Hospital. External beam therapy

    International Nuclear Information System (INIS)

    Since 1971, Itabashi hospital of Teikyo University began using the practice of radiotherapy. Since then, data has been compiled in notebook form. This was a slow and inconvenient way to log data. We tried to change the out-of-date form to a more convenient and available one. We input the radiotherapy (RT) number, ID, name, sex, primary disease, the refered department and the initial date of the radiotherapy of all cases into a PC. A total of 5072 new patients were summed up by the end of 2001. The number of the new patients has been increasing annually, and there were 235 cases in 2001. The largest group in these patients was head and neck tumors, which consisted 1180 patients (23.3%). The second largest group was gynecologic tumors, 766 cases (15.1%), and the third one was respiratory tumors, 648 cases (12.8%). The number of the respiratory tumors, the digestive tumors and the urological tumors have been increasing markedly, which became more than twice the number in 30 years. Especially, the ratio of the respiratory group and the digestive group have increased every year. The ratio of gynecologic tumors decreased markedly (25.1%→9.3%). To answer the current demand of the information disclosure, we should continue to open the up-to-date status and the therapeutic results of our practice. (author)

  3. Harmonics generation of a terahertz wakefield free-electron laser from a dielectric loaded waveguide excited by a direct current electron beam.

    Science.gov (United States)

    Li, Weiwei; Lu, Yalin; He, Zhigang; Jia, Qika; Wang, Lin

    2016-06-01

    We propose to generate high-power terahertz (THz) radiation from a cylindrical dielectric loaded waveguide (DLW) excited by a direct-current electron beam with the harmonics generation method. The DLW supports a discrete set of modes that can be excited by an electron beam passing through the structure. The interaction of these modes with the co-propagating electron beam results in micro-bunching and the coherent enhancement of the wakefield radiation, which is dominated by the fundamental mode. By properly choosing the parameters of DLW and beam energy, the high order modes can be the harmonics of the fundamental one; thus, high frequency radiation corresponding to the high order modes will benefit from the dominating bunching process at the fundamental eigenfrequency and can also be coherently excited. With the proposed method, high power THz radiation can be obtained with an easily achievable electron beam and a large DLW structure. PMID:27244388

  4. Numerical simulation of transport of a high-current electron beam generated by the secondary-emission cathode gun in a decreasing solenoidal field

    International Nuclear Information System (INIS)

    The software tool has been developed for computing the electron beam formation by means of the secondary-emission cathode magnetron gun in the electron energy range between 30 and 65 keV at beam transport in a decreasing magnetic field of the solenoid. Numerical simulation data on the tubular electron flow motion and visualization are presented. The beam current was investigated versus the amplitude and gradient of the field decrease, and also, versus the initial beam particle distribution in the phase space. It has been found that for the given simulation conditions, the magnetic field reconfiguration has an effect only on the total displacement of the electron beam, without causing a noticeable change in the shape of the final flow distribution along the longitudinal coordinate

  5. A Measurement of Neutrino Charged Current Interactions and a Search for Muon Neutrino Disappearance with the Fermilab Booster Neutrino Beam

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, Yasuhiro; /Kyoto U.

    2011-01-01

    In this thesis, we report on a measurement of muon neutrino inclusive charged current interactions on carbon in the few GeV region, using the Fermilab Booster Neutrino Beam. The all neutrino mode data collected in the SciBooNE experiment is used for this analysis. We collected high-statistics CC interaction sample at SciBooNE, and extracted energy dependent inclusive charged current interaction rates and cross sections for a wide energy range from 0.25 GeV to {approx}3 GeV. We measure the interaction rates with 6-15% precision, and the cross sections with 10-30% precision. We also made an energy integrated measurements, with the precisions of 3% for the rate, and 8% for the cross section measurements. This is the first measurement of the CC inclusive cross section on carbon around 1 GeV. This inclusive interaction measurement is nearly free from effects of hadron re-interactions in the nucleus. Hence, it is complementary to other exclusive cross section measurements, and essential to understand the neutrino interaction cross sections in the few GeV region, which is relevant to ongoing and future neutrino oscillation experiments. This analysis also provides the normalization for SciBooNE's previous cross section ratio measurements for charged current coherent pion production and neutral current neutral pion production. Then, a precise comparison between our previous measurements and the model predictions becomes possible. The result of the interaction rate measurement is used to constrain the product of the neutrino flux and the cross section at the other experiment on the Fermilab Booster Neutrino Beam: Mini-BooNE. We conducted a search for short-baseline muon neutrino disappearance using data both from SciBooNE and MiniBooNE, to test a possible neutrino oscillation with sterile neutrinos which is suggested by the LSND experiment. With this constraint by SciBooNE, we significantly reduced the flux and the cross section uncertainties at MiniBooNE, and achieved

  6. Electronic regulation of the SPS extraction quadrupole current pulse shape for improved stability of the extracted beam

    CERN Document Server

    Carlier, E; Vossenberg, Eugène B; CERN. Geneva. SPS and LEP Division

    1996-01-01

    In order to minimise the event pile-up and therefore optimise the detection efficiency, Chorus and Nomad experiments ask for a long and rectangular spill profile. At present the fast-slow extractio n is generated by driving the beam into a quadrupolar-octopolar resonance by exciting a quadrupole magnet with a semi-trapezoidal current [1]. The trapezoidal pulse shape is obtained by dischargin g a capacitor into the magnet coils. After a few milliseconds of undamped discharge a fixed resistor is switched into the circuit. The attenuation is then higher and the sine wave continues with a lower gradient. The two gradients can be adjusted by varying the initial capacitor voltage and the time at which the resistor is switched into the circuit. A further degree of freedom in determini ng the spill shape has been added by allowing the possibility of changing the second slope value independently of the initial conditions. This task is achieved by means of a variable current sour ce added in parallel to the fixed resis...

  7. Molecular beam deposition of LaLuO3 thin films with high dielectric constant and low leakage current

    International Nuclear Information System (INIS)

    Although the introduction of hafnium-based high-κ dielectrics in the next CMOS generation has been announced, the implementation of materials with a dielectric constant even higher than 20 will be required in order to satisfy the future demands in CMOS applications. In this contribution, we report on lanthanum lutetium oxide, a ternary rare-earth based material that has recently appeared as a promising candidate1. LaLuO3 thin films were grown on (100) Si substrates by molecular beam deposition and electrically characterized by capacitance-voltage (C-V) and current-voltage (I-V) measurements. Additionally, a combination of characterization methods such as Rutherford backscattering spectrometry, transmission electron microscopy, X-ray reflectometry, and X-ray diffraction were used to study their composition and microstructural characteristics. We will present results of a systematic investigation on the film preparation, which allowed the deposition of LaLuO3 thin films with EOT ≤1.5 nm, low leakage current densities of about 5 mA/cm2 at -1 V gate bias, and higher κ-values around 30

  8. Complex reduction coefficient for a cylindrical electron beam with variable amplitude of the variable current component in the TWT

    Directory of Open Access Journals (Sweden)

    Chasnyk V. I.

    2013-12-01

    Full Text Available The conventional approach to calculating the space charge for the traveling-wave tube (TWT with phase velocity jumps is to use the same values of the depression coefficient as the ones for homogeneous helical TWTs. However, if the variable component of the exciting current in the expressions for determining the reduction coefficient is changed in amplitude, then the reduction factor is a complex value. Perhaps the neglect of this fact can significantly affect the volume discharge calculated value, and hence the non-synchronization parameter, for those of its values, which are characteristic of the TWT with a phase velocity jump. In this paper, formulas has been obtained for computation of real and imaginary parts of the complex reduction coefficient for a cylindrical electrons beam with exponential variable amplitude of variable current component in the TWT. Influence of complex reduction coefficient on the parameters of the TWT operating in the linear mode is estimated. It is shown that taking into account the imaginary part of the reduction coefficient for linear operation of the TWT makes it possible to change the estimated amount of space charge 1.5 to 2 times, which in its turn has quite a strong effect on the formation of the initial conditions of the nonlinear mode and, subsequently, on the output characteristics of the TWT.

  9. Internal gastargets in AmPS

    Science.gov (United States)

    Kaan, A. P.; Postma, O.; van den Brand, J. F. J.; van Leeuwen, E.; Doets, M.; Kraan, M.

    1997-05-01

    Internal gas targets in AmPS A.P. Kaan, O. Postma, J.F.J. van den Brand, E. van Leeuwen, M. Doets, M. Kra= an National Institute for Nuclear Physics and High Energy Physics; Kruislaan 409; 1098 SJ Amsterdam; Holland In the Amsterdam Puls Stretcher/storage ring AmPS(1 GeV electrons), we designed a set-up in order to accommodate a gas target with a density of 1016 mol/cm2. The storage cell needed for this purpose is a aluminium tube with a length of 40 cm, a diameter of 15 mm and a wall thickness of 25 =B5m. Three sets of conductance limiters on both sides of the target, combined with dry turbopumps are designed to be used as differential pumping stations. These limiters cause discontinuities in the beam path and must therefor be retractable and radio frequency compatible in both positions. Low =B5 materials must be used because of the depolarisation effects of changing magnetic fields. The calculations show that the flow resistance's are sufficient to reduce the load of the getter pumps to a level with which the lifetime of the pump elements remain acceptable. The design of the mechanics and the vacuum system will be explained. Recent results from the measurements after installation in combination with the influence on the lifetime on the beam will be presented

  10. Sleutelmag en amp

    Directory of Open Access Journals (Sweden)

    P. J. Rossouw

    1985-06-01

    Full Text Available As die Heidelbergse Kategismus (Sondag 31 handel oor die sleutels van die Koninkryk, dan word die betrokkenheid van die ampte slegs per implikasie veronderstel. Meer eksplisiet word die amp en sleutelmag in die Nederlandse Geloofsbelydenis gekoppel; “ons glo dat hierdie ware kerk ooreenkomstig die geestelike bestuurswyse wat ons Here ons in sy Woord geleer het, geregeer moet word... hulle (moet sorg dra dat die ware godsdiens onderhou (word, die ware leer orals versprei, die oortreders op geestelike wyse vermaan en in toom gehou (word... (N.G.B. art. 30 en: “Ons glo verder dat die regeerders van die kerk, al is dit nuttig en goed om onder mekaar ’n bepaalde orde tot instandhouding van die liggaam van die kerk in te stel en te handhaaf, tog noukeurig moet oppas om nie af te wyk van wat Christus, ons enigste Meester, vir ons ingestel het nie... Ons aanvaar derhalwe slegs wat kan dien om eendrag en eenheid te bewaar en te bevorder, en om alles in gehoorsaamheid van God te onderhou. Daarvoor is nodig die ban en alles wat daarmee saamhang, toegepas ooreenkomstig die Woord van God” (N.G.B. art. 32.

  11. Electrostatic solitary waves in current layers: from Cluster observations during a super-substorm to beam experiments at the LAPD

    Directory of Open Access Journals (Sweden)

    J. S. Pickett

    2009-06-01

    Full Text Available Electrostatic Solitary Waves (ESWs have been observed by several spacecraft in the current layers of Earth's magnetosphere since 1982. ESWs are manifested as isolated pulses (one wave period in the high time resolution waveform data obtained on these spacecraft. They are thus nonlinear structures generated out of nonlinear instabilities and processes. We report the first observations of ESWs associated with the onset of a super-substorm that occurred on 24 August 2005 while the Cluster spacecraft were located in the magnetotail at around 18–19 RE and moving northward from the plasma sheet to the lobes. These ESWs were detected in the waveform data of the WBD plasma wave receiver on three of the Cluster spacecraft. The majority of the ESWs were detected about 5 min after the super-substorm onset during which time 1 the PEACE electron instrument detected significant field-aligned electron fluxes from a few 100 eV to 3.5 keV, 2 the EDI instrument detected bursts of field-aligned electron currents, 3 the FGM instrument detected substantial magnetic fluctuations and the presence of Alfvén waves, 4 the STAFF experiment detected broadband electric and magnetic waves, ion cyclotron waves and whistler mode waves, and 5 CIS detected nearly comparable densities of H+ and O+ ions and a large tailward H+ velocity. We compare the characteristics of the ESWs observed during this event to those created in the laboratory at the University of California-Los Angeles Plasma Device (LAPD with an electron beam. We find that the time durations of both space and LAPD ESWs are only slightly larger than the respective local electron plasma periods, indicating that electron, and not ion, dynamics are responsible for generation of the ESWs. We have discussed possible mechanisms for generating the ESWs in space, including the beam and kinetic Buneman type instabilities and the acoustic instabilities. Future studies will examine these mechanisms in

  12. A Study of Charged Current Single Charged Pion Productions on Carbon in a Few-GeV Neutrino Beam

    Energy Technology Data Exchange (ETDEWEB)

    Hiraide, Katsuki; /Kyoto U.

    2009-01-01

    Understanding single charged pion production via neutrino-nucleus charged current interaction in the neutrino energy region of a few GeV is essential for future neutrino oscillation experiments since this process is a dominant background for {nu}{sub {mu}} {yields} {nu}{sub x} oscillation measurements. There are two contributions to this process: single pion production via baryonic resonance ({nu}{sub {mu}}N {yields} {mu}{sup -} N{pi}{sup +}) and coherent pion production interacting with the entire nucleus ({nu}{sub {mu}}A {yields} {mu}{sup -} A{pi}{sup +}), where N is nucleon in the nucleus and A is the nucleus. The purpose of the study presented in this thesis is a precise measurement of charged current single charged pion productions, resonant and coherent pion productions, with a good final state separation in the neutrino energy region of a few GeV. In this thesis, we focus on the study of charged current coherent pion production from muon neutrinos scattering on carbon, {nu}{sub {mu}} {sup 12}C {yields} {mu}{sup -12}C{pi}{sup +}, in the SciBooNE experiment. This is motivated by the fact that without measuring this component first, the precise determination of resonant pion production cross section can not be achieved since the contribution of coherent pion production in the region of small muon scattering angle is not small. Furthermore, the coherent process is particularly interesting because it is deeply rooted in fundamental physics via Adler's partially conserved axial-vector current theorem. We took data from June 2007 until August 2008, in both the neutrino and antineutrino beam. In total, 2.52 x 10{sup 20} protons on target were collected. We have performed a search for charged current coherent pion production by using SciBooNE's full neutrino data set, corresponding to 0.99 x 10{sup 20} protons on target. No evidence for coherent pion production is observed. We set 90% confidence level upper limits on the cross section ratio of charged

  13. A Study of Charged Current Single Charged Pion Productions on Carbon in a Few-GeV Neutrino Beam

    Energy Technology Data Exchange (ETDEWEB)

    Hiraide, Katsuki [Kyoto Univ. (Japan)

    2009-01-01

    Understanding single charged pion production via neutrino-nucleus charged current interaction in the neutrino energy region of a few GeV is essential for future neutrino oscillation experiments since this process is a dominant background for vμ → vx oscillation measurements. There are two contributions to this process: single pion production via baryonic resonance (vμN → μ-+) and coherent pion production interacting with the entire nucleus (vμA → μ-+), where N is nucleon in the nucleus and A is the nucleus. The purpose of the study presented in this thesis is a precise measurement of charged current single charged pion productions, resonant and coherent pion productions, with a good final state separation in the neutrino energy region of a few GeV. In this thesis, we focus on the study of charged current coherent pion production from muon neutrinos scattering on carbon, vμ 12C → μ-12+, in the SciBooNE experiment. This is motivated by the fact that without measuring this component first, the precise determination of resonant pion production cross section can not be achieved since the contribution of coherent pion production in the region of small muon scattering angle is not small. Furthermore, the coherent process is particularly interesting because it is deeply rooted in fundamental physics via Adler's partially conserved axial-vector current theorem. We took data from June 2007 until August 2008, in both the neutrino and antineutrino beam. In total, 2.52 x 1020 protons on target were collected. We have performed a search for charged current coherent pion production by using SciBooNE's full neutrino data set, corresponding to 0.99 x 1020 protons on target. No evidence for coherent pion production is observed. We set 90% confidence level upper limits on the cross section ratio

  14. Temperature behaviour of photoluminescence and electron-beam-induced current recombination behaviour of extended defects in solar grade silicon

    CERN Document Server

    Arguirov, T; Kittler, M; Reif, J

    2002-01-01

    The temperature dependence of D-band and band-to-band (BB) luminescence was measured in EFG samples between 80 K and room temperature for defects/dislocations presenting different amounts of contamination. The contamination density was estimated from the temperature behaviour of the electron-beam-induced current contrast, ranging between about 10 sup 4 and 10 sup 6 impurities cm sup - sup 1 dislocation length. The D1 line became already visible at room temperature but its intensity was found to exhibit a maximum at about 150 K. D2, D3 and D4 start to show up at about 250, 190 and 170 K, respectively, and increase their intensities upon lowering temperature. At room temperature the width of the D1 line is broad and becomes narrower upon lowering the temperature. D2 shows the opposite behaviour. The intensities of D1 and D2 were observed to show strong variations across the sample, whereas this was not observed for the pair D4/D3. In particular, the origin of the lines D1 and D2 is still far from being understo...

  15. Current External Beam Radiation Therapy Quality Assurance Guidance: Does It Meet the Challenges of Emerging Image-Guided Technologies?

    International Nuclear Information System (INIS)

    The traditional prescriptive quality assurance (QA) programs that attempt to ensure the safety and reliability of traditional external beam radiation therapy are limited in their applicability to such advanced radiation therapy techniques as three-dimensional conformal radiation therapy, intensity-modulated radiation therapy, inverse treatment planning, stereotactic radiosurgery/radiotherapy, and image-guided radiation therapy. The conventional QA paradigm, illustrated by the American Association of Physicists in Medicine Radiation Therapy Committee Task Group 40 (TG-40) report, consists of developing a consensus menu of tests and device performance specifications from a generic process model that is assumed to apply to all clinical applications of the device. The complexity, variation in practice patterns, and level of automation of high-technology radiotherapy renders this 'one-size-fits-all' prescriptive QA paradigm ineffective or cost prohibitive if the high-probability error pathways of all possible clinical applications of the device are to be covered. The current approaches to developing comprehensive prescriptive QA protocols can be prohibitively time consuming and cost ineffective and may sometimes fail to adequately safeguard patients. It therefore is important to evaluate more formal error mitigation and process analysis methods of industrial engineering to more optimally focus available QA resources on process components that have a significant likelihood of compromising patient safety or treatment outcomes

  16. Current external beam radiation therapy quality assurance guidance: does it meet the challenges of emerging image-guided technologies?

    Science.gov (United States)

    Palta, Jatinder R; Liu, Chihray; Li, Jonathan G

    2008-01-01

    The traditional prescriptive quality assurance (QA) programs that attempt to ensure the safety and reliability of traditional external beam radiation therapy are limited in their applicability to such advanced radiation therapy techniques as three-dimensional conformal radiation therapy, intensity-modulated radiation therapy, inverse treatment planning, stereotactic radiosurgery/radiotherapy, and image-guided radiation therapy. The conventional QA paradigm, illustrated by the American Association of Physicists in Medicine Radiation Therapy Committee Task Group 40 (TG-40) report, consists of developing a consensus menu of tests and device performance specifications from a generic process model that is assumed to apply to all clinical applications of the device. The complexity, variation in practice patterns, and level of automation of high-technology radiotherapy renders this "one-size-fits-all" prescriptive QA paradigm ineffective or cost prohibitive if the high-probability error pathways of all possible clinical applications of the device are to be covered. The current approaches to developing comprehensive prescriptive QA protocols can be prohibitively time consuming and cost ineffective and may sometimes fail to adequately safeguard patients. It therefore is important to evaluate more formal error mitigation and process analysis methods of industrial engineering to more optimally focus available QA resources on process components that have a significant likelihood of compromising patient safety or treatment outcomes. PMID:18406911

  17. Improving corrosion and wear resistance of FV520B steel by high current pulsed electron beam surface treatment

    International Nuclear Information System (INIS)

    Highlights: • HCPEB surface treatment was conducted on FV520B steel. • Surface layer ∼10 μm was refined with elements homogenization. • Remelted layer exhibited 〈2 0 0〉 preferential orientation. • Corrosion potential increased and corrosion rate decreased one order of magnitude. • Wear resistance increased by 3 times. - Abstract: High current pulsed electron beam (HCPEB) surface treatment was conducted on FV520B steel with accelerating voltage 27 kV, pulse duration 2.5 μs, energy density 5 J/cm2 and 1–25 pulses. The surface microstructure and element distribution were examined by using scanning electron microscope (SEM), electron probe micro-analysis (EPMA) and X-ray diffraction (XRD) methods. After HCPEB treatments, the surface microstructure became refined and uniform with an average grain size less than 2 μm and a preferential solidification orientation in 〈2 0 0〉 direction. The thickness of surface remelted layer was ∼4 μm. The initial precipitated particles in surface layer of depth ∼10 μm were dissolved into the base matrix and gave a homogenous element distribution. The HCPEB modified surface exhibited an effective improvement in corrosion and wear resistance. The corrosion potential shifted towards positive and the corrosion rate decreased nearly one order of magnitude, while the wear resistance after 25 pulses of HCPEB treatment increased by 3 times as compared with the initial FV520B steel

  18. WC/Co composite surface structure and nano graphite precipitate induced by high current pulsed electron beam irradiation

    International Nuclear Information System (INIS)

    High current pulsed electron beam (HCPEB) irradiation was conducted on a WC-6% Co hard alloy with accelerating voltage of 27 kV and pulse duration of 2.5 μs. The surface phase structure was examined by using glancing-angle X-ray diffraction (GAXRD), scanning electron microscope (SEM) and high resolution transmission electron microscope (HRTEM) methods. The surface tribological properties were measured. It was found that after 20 pulses of HCPEB irradiation, the surface structure of WC/Co hard alloy was modified dramatically and composed of a mixture of nano-grained WC1−x, Co3W9C4, Co3W3C phases and graphite precipitate domains ∼50 nm. The friction coefficient of modified surface decreased to ∼0.38 from 0.6 of the initial state, and the wear rate reduced from 8.4 × 10−5 mm3/min to 6.3 × 10−6 mm3/min, showing a significant self-lubricating effect.

  19. WC/Co composite surface structure and nano graphite precipitate induced by high current pulsed electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Hao, S.Z., E-mail: ebeam@dlut.edu.cn [Key Laboratory of Materials Modification and School of Physics and Optoelectronics Engineering, Dalian University of Technology, Dalian 116024 (China); Zhang, Y. [Key Laboratory of Materials Modification and School of Physics and Optoelectronics Engineering, Dalian University of Technology, Dalian 116024 (China); School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870 (China); Xu, Y. [Key Laboratory of Materials Modification and School of Physics and Optoelectronics Engineering, Dalian University of Technology, Dalian 116024 (China); College of Materials Science and Engineering, Liaoning Technical University, Fuxin 123000 (China); Gey, N.; Grosdidier, T. [Université de Lorraine, Laboratoire d’Etude des Microstructures et de Mécanique des Matériaux (LEM3), CNRS UMR 7239, Ile du Saulcy, 57045 Metz (France); Université de Lorraine, Laboratoire d’Excellence on Design of Alloy Metals for Low-Mass Structure (DAMAS), Ile du Saulcy, 57045 Metz (France); Dong, C. [Key Laboratory of Materials Modification and School of Physics and Optoelectronics Engineering, Dalian University of Technology, Dalian 116024 (China); Université de Lorraine, Laboratoire d’Excellence on Design of Alloy Metals for Low-Mass Structure (DAMAS), Ile du Saulcy, 57045 Metz (France)

    2013-11-15

    High current pulsed electron beam (HCPEB) irradiation was conducted on a WC-6% Co hard alloy with accelerating voltage of 27 kV and pulse duration of 2.5 μs. The surface phase structure was examined by using glancing-angle X-ray diffraction (GAXRD), scanning electron microscope (SEM) and high resolution transmission electron microscope (HRTEM) methods. The surface tribological properties were measured. It was found that after 20 pulses of HCPEB irradiation, the surface structure of WC/Co hard alloy was modified dramatically and composed of a mixture of nano-grained WC{sub 1−x}, Co{sub 3}W{sub 9}C{sub 4}, Co{sub 3}W{sub 3}C phases and graphite precipitate domains ∼50 nm. The friction coefficient of modified surface decreased to ∼0.38 from 0.6 of the initial state, and the wear rate reduced from 8.4 × 10{sup −5} mm{sup 3}/min to 6.3 × 10{sup −6} mm{sup 3}/min, showing a significant self-lubricating effect.

  20. Halo Evolution of Hypereutectic Al-17.5Si Alloy Treated with High-Current Pulsed Electron Beam

    Directory of Open Access Journals (Sweden)

    L. Hu

    2015-01-01

    Full Text Available Halo evolution of an Al-17.5Si alloy surface after treatment with increasing pulse numbers of a high-current pulsed electron beam (HCPEB was investigated. A halo is a ring microstructure resembling a bull’s eye. SEM results indicate that the nanocrystallization of halo induced by HCPEB treatment leads to gradual diffusion of the Si phase. Multiple pulses numbers cause the Si phase to be significantly refined and uniformly distributed. In addition, nanosilicon particles with a grain size of 30~100 nm were formed after HCPEB treatment, as shown by TEM observation. XRD results indicate that Si diffraction peaks broadened after HCPEB treatment. The microhardness tests demonstrate that the microhardness at the midpoint from the halo edge to center decreased sharply from 9770.7 MPa at 5 pulses to 2664.14 MPa at 25 pulses. The relative wear resistance of a 15-pulse sample is effectively improved by a factor of 6.5, exhibiting optimal wear resistance.

  1. Target volume definition for external beam partial breast radiotherapy: Clinical, pathological and technical studies informing current approaches

    International Nuclear Information System (INIS)

    Partial breast irradiation (PBI) is currently under investigation in several phase III trials and, following a recent consensus statement, its use off-study may increase despite ongoing uncertainty regarding optimal target volume definition. We review the clinical, pathological and technical evidence for target volume definition in external beam partial breast irradiation (EB-PBI). The optimal method of tumour bed (TB) delineation requires X-ray CT imaging of implanted excision cavity wall markers. The definition of clinical target volume (CTV) as TB plus concentric 15 mm margins is based on the anatomical distribution of multifocal and multicentric disease around the primary tumour in mastectomy specimens, and the clinical locations of local tumour relapse (LR) after breast conservation surgery. If the majority of LR originate from foci of residual invasive and/or intraduct disease in the vicinity of the TB after complete microscopic resection, CTV margin logically takes account of the position of primary tumour within the surgical resection specimen. The uncertain significance of independent primary tumours as sources of preventable LR, and of wound healing responses in stimulating LR, increases the difficulties in defining optimal CTV. These uncertainties may resolve after long-term follow-up of current PBI trials. By contrast, a commonly used 10 mm clinical to planning target volume (PTV) margin has a stronger evidence base, although departmental set-up errors need to be confirmed locally. A CTV-PTV margin >10 mm may be required in women with larger breasts and/or large seromas, whilst the role of image-guided radiotherapy with or without TB markers in reducing CTV-PTV margins needs to be explored.

  2. Assisted Medical Procedures (AMP) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Documentation and Development: The AMP was initially being developed as part the Advanced Integrated Clinical System (AICS)-Guided Medical Procedure System for the...

  3. Parametric Study of the current limit within a single driver-scale transport beam line of an induction Linac for Heavy Ion Fusion

    International Nuclear Information System (INIS)

    The High Current Experiment (HCX) at Lawrence Berkeley National Laboratory is part of the US program that explores heavy-ion beam as the driver option for fusion energy production in an Inertial Fusion Energy (IFE) plant. The HCX is a beam transport experiment at a scale representative of the low-energy end of an induction linear accelerator driver. The primary mission of this experiment is to investigate aperture fill factors acceptable for the transport of space-charge-dominated heavy-ion beams at high intensity (line charge density ∼0.2 (micro)C/m) over long pulse durations (4 (micro)s) in alternating gradient focusing lattices of electrostatic or magnetic quadrupoles. This experiment is testing transport issues resulting from nonlinear space-charge effects and collective modes, beam centroid alignment and steering, envelope matching, image charges and focusing field nonlinearities, halo and, electron and gas cloud effects. We present the results for a coasting 1 MeV K+ ion beam transported through ten electrostatic quadrupoles. The measurements cover two different fill factor studies (60% and 80% of the clear aperture radius) for which the transverse phase-space of the beam was characterized in detail, along with beam energy measurements and the first halo measurements. Electrostatic quadrupole transport at high beam fill factor (∼80%) is achieved with acceptable emittance growth and beam loss. We achieved good envelope control, and re-matching may only be needed every ten lattice periods (at 80% fill factor) in a longer lattice of similar design. We also show that understanding and controlling the time dependence of the envelope parameters is critical to achieving high fill factors, notably because of the injector and matching section dynamics

  4. Parametic Study of the current limit within a single driver-scaletransport beam line of an induction Linac for Heavy Ion Fusion

    Energy Technology Data Exchange (ETDEWEB)

    Prost, Lionel Robert

    2007-02-14

    The High Current Experiment (HCX) at Lawrence Berkeley National Laboratory is part of the US program that explores heavy-ion beam as the driver option for fusion energy production in an Inertial Fusion Energy (IFE) plant. The HCX is a beam transport experiment at a scale representative of the low-energy end of an induction linear accelerator driver. The primary mission of this experiment is to investigate aperture fill factors acceptable for the transport of space-charge-dominated heavy-ion beams at high intensity (line charge density {approx}0.2 {micro}C/m) over long pulse durations (4 {micro}s) in alternating gradient focusing lattices of electrostatic or magnetic quadrupoles. This experiment is testing transport issues resulting from nonlinear space-charge effects and collective modes, beam centroid alignment and steering, envelope matching, image charges and focusing field nonlinearities, halo and, electron and gas cloud effects. We present the results for a coasting 1 MeV K{sup +} ion beam transported through ten electrostatic quadrupoles. The measurements cover two different fill factor studies (60% and 80% of the clear aperture radius) for which the transverse phase-space of the beam was characterized in detail, along with beam energy measurements and the first halo measurements. Electrostatic quadrupole transport at high beam fill factor ({approx}80%) is achieved with acceptable emittance growth and beam loss. We achieved good envelope control, and re-matching may only be needed every ten lattice periods (at 80% fill factor) in a longer lattice of similar design. We also show that understanding and controlling the time dependence of the envelope parameters is critical to achieving high fill factors, notably because of the injector and matching section dynamics.

  5. Relativistic high-current electron beams in dense plasmas in the context of the fast ignition of inertially confined fusion targets

    International Nuclear Information System (INIS)

    We present the results of two similar experiments on laser generated relativistic electron beam (REB) transport in aluminum samples related to the fast ignition (FI) of inertially confined fusion targets. Their goal was to characterize high current density REB energy losses in solid and compressed samples, as the viability of the FI scheme is highly determined by the amount of such energy losses. The experiments were performed on the JLF-Titan laser system. A REB was generated by an intense ps laser beam ≥ 1020 W.cm-2 in planar targets compressed by a ns laser beam ≥ 1013 W.cm-2 leading to REB current densities jh ∼ 1011 A.cm-2 in the aluminum sample under study. A variation of resistive energy losses between solid and compressed samples was observed for the thickest ones as predicted by numerical hybrid simulations. (authors)

  6. Characterization of charged defects in Cd_xHg_(1-x)Te and CdTe crystals by electron beam induced current and scanning tunneling spectroscopy

    OpenAIRE

    Panin, G. N.; Diaz-Guerra, C.; Piqueras de Noriega, Javier

    1998-01-01

    A correlative study of the electrically active defects of CdxHg1-xTe and CdTe crystals has been carried out using a scanning electron microscope/scanning tunneling microscope (SEM/STM) combined system. Charged structural and compositional defects were revealed by the remote electron beam induced current (REBIC) mode of the scanning electron microscope. The electronic inhomogeneities of the samples were analyzed with nm resolution by current imaging tunneling spectroscopy (CITS) measurements, ...

  7. Electrical characterization of ZnO ceramics by scanning tunneling spectroscopy and beam-induced current in the scanning tunneling microscope

    OpenAIRE

    Díaz-Guerra Viejo, Carlos; Piqueras de Noriega, Javier

    1999-01-01

    A correlative study of the electrically active grain boundary structure of ZnO polycrystals has been carried out using a scanning electron microscope/scanning tunneling microscope (SEM/STM) combined instrument. Current imaging tunneling spectroscopy (CITS) measurements reveal reduced surface band gaps, as compared with grain interiors, at the charged boundaries imaged by SEM-based remote electron beam induced current (REBIC). ZnO grain boundaries were also imaged in the STM-REBIC mode with a ...

  8. Multiple Facets of cAMP Signalling and Physiological Impact: cAMP Compartmentalization in the Lung

    Directory of Open Access Journals (Sweden)

    Martina Schmidt

    2012-11-01

    Full Text Available Therapies involving elevation of the endogenous suppressor cyclic AMP (cAMP are currently used in the treatment of several chronic inflammatory disorders, including chronic obstructive pulmonary disease (COPD. Characteristics of COPD are airway obstruction, airway inflammation and airway remodelling, processes encompassed by increased airway smooth muscle mass, epithelial changes, goblet cell and submucosal gland hyperplasia. In addition to inflammatory cells, airway smooth muscle cells and (myofibroblasts, epithelial cells underpin a variety of key responses in the airways such as inflammatory cytokine release, airway remodelling, mucus hypersecretion and airway barrier function. Cigarette smoke, being next to environmental pollution the main cause of COPD, is believed to cause epithelial hyperpermeability by disrupting the barrier function. Here we will focus on the most recent progress on compartmentalized signalling by cAMP. In addition to G protein-coupled receptors, adenylyl cyclases, cAMP-specific phospho-diesterases (PDEs maintain compartmentalized cAMP signalling. Intriguingly, spatially discrete cAMP-sensing signalling complexes seem also to involve distinct members of the A-kinase anchoring (AKAP superfamily and IQ motif containing GTPase activating protein (IQGAPs. In this review, we will highlight the interaction between cAMP and the epithelial barrier to retain proper lung function and to alleviate COPD symptoms and focus on the possible molecular mechanisms involved in this process. Future studies should include the development of cAMP-sensing multiprotein complex specific disruptors and/or stabilizers to orchestrate cellular functions. Compartmentalized cAMP signalling regulates important cellular processes in the lung and may serve as a therapeutic target.

  9. Transimssion and compression of an intense relativistic electron beam produced by a converging annular diode with return current feedback through the cathode. Part II. The experiments

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, J.G.; Schuch, R.L.

    1976-02-01

    The complete results of the experiments with the converging annular diode within return current feedback through the cathode (Triax) are reported herein. The diode was designed to focus a relativistic high-current electron beam to a small focus. It did confirm the Triaxial theory detailed in Part I, and it did achieve a factor of 10 areal compression with 50% efficiency (which was below expectations). There were two principal reasons for this shortfall. First, the rapid diode plasma motion of 10 cm/..mu..sec that was discovered necessitated the use of larger A-K gaps than expected and led to thicker beam sheets than are needed for good focusing. Second, the intrinsic angular spread of the electrons, even from the best cathode surfaces, introduced excessive angular momentum into the beam so that only a minor portion of the electrons could reach the axis. However, the yield of useful information about diode physics in general and about the influence of prepulse, the role of diode plasmas, the motion of energetic beams within conducting boundaries, diode emission properties, and diode diagnostic techniques in particle has had a significant and useful impact on the electron beam program at Sandia.

  10. Expression profiles of antimicrobial peptides (AMPs) and their regulation by Relish

    Science.gov (United States)

    Wang, Dongdong; Li, Fuhua; Li, Shihao; Wen, Rong; Xiang, Jianhai

    2012-07-01

    Antimicrobial peptides (AMPs), as key immune effectors, play important roles in the innate immune system of invertebrates. Different types of AMPs, including Penaeidin, Crustin, ALF (antilipopolysaccharide factor) have been identified in different penaeid shrimp; however, systematic analyses on the function of different AMPs in shrimp responsive to different types of bacteria are very limited. In this study, we analyzed the expression profiles of AMPs in the Chinese shrimps, Fenneropenaeus chinensis, simultaneously by real-time RT-PCR (reverse transcription-polymerase chain reaction) when shrimp were challenged with Micrococcus lysodeikticus (Gram-positive, G+) or Vibrio anguillarium (Gram-negative, G-). Different AMPs showed different expression profiles when shrimp were injected with one type of bacterium, and one AMP also showed different expression profiles when shrimp were challenged with different bacteria. Furthermore, the expression of these AMPs showed temporal expression profiles, suggesting that different AMPs function coordinately in bacteria-infected shrimp. An RNA interference approach was used to study the function of the Relish transcription factor in regulating the transcription of different AMPs. The current study showed that Relish could regulate the transcription of different AMPs in shrimp. Differential expression profiles of AMPs in shrimp injected with different types of bacteria indicated that a complicated antimicrobial response network existed in shrimp. These data contribute to our understanding of immunity in shrimp and may provide a strategy for the control of disease in shrimp.

  11. The LANSCE Low Momentum Beam Monitor

    CERN Document Server

    Merl, R

    2004-01-01

    A diagnostic has been developed at the Los Alamos Neutron Science Center (LANSCE) for the purpose of identifying low momentum beam tails in the linear accelerator. These tails must be eliminated in order to maintain the transverse and longitudinal beam size. Instead of the currently used phosphor camera system, this instrument consists of a Multi Wire Proportional Chamber (MWPC) front end coupled to an EPICS compliant VME-based electronics package. Low momentum tails are detected with a resolution of 5 mm in the MWPC at a high dispersion point near a bending magnet. While phosphor is typically not sensitive in the nano amp range, the MWPC is sensitive down to about a pico amp. The electronics package processes the signals from each of the MWPC wires to generate an array of beam currents at each of the lower energies. The electronics has an analog front end with a high-speed analog to digital converter for each wire. Data from multiple wires are processed with an embedded digital signal processor and results p...

  12. Neutralization and transport of high-current proton beams in a two-stage linear induction accelerator

    Science.gov (United States)

    Golkowski, Cz.; Kerslick, G. S.; Nation, J. A.; Ivers, J.

    1992-03-01

    Experimental results on the propagation and transport efficiency of a 1 MV, 5 kA, 50 ns annular proton beam through a two-stage linear induction accelerator are presented. The beam is generated in a magnetically insulated diode and propagates with high-efficiency along a 0.6 T axial magnetic field to a second accelerating gap located 30 cm downstream. The second accelerating gap increases the beam energy to 1.3 MeV. A full-cusp geometry provides the magnetic insulation in both the diode and the second gap. We report in this paper an 86% (±5%) transport efficiency and an increase of 1.6° in the beam divergence for propagation through the post acceleration gap.

  13. Experiments with heavy-ion beams and RF-tests with the 27 MHz high-current spiral-RFQ-prototype

    International Nuclear Information System (INIS)

    A Spiral-RFQ has been built and operated with Ar+-beams up to 8 mA. In rf-tests very high electrode voltages were reached at design duty factor. The aim of the experiments was the test of the Spiral-RFQ for the High Current Injector (HSI), which is planned at GSI to fill the Heavy Ion Synchrotron (SIS) up to its space charge limit. This Spiral-RFQ, a prototype for the HSI-RFQ, covers the crucial matching and bunching section of the electrodes. It is capable to produce ion beams of high brilliance. The results of recent beam experiments with Ar+ and rf-tests will be presented together with work for future plasma physics experiments. (author)

  14. Gamma and neutron irradiation tests on commercial IC op amps

    International Nuclear Information System (INIS)

    Experimental results of gamma and neutron irradiation tests on 30 types of integrated-circuit operational amplifiers from 11 manufacturers are presented. All units were low-cost, commercial-grade devices. Op amps were evaluated for changes in offset voltage, input bias current, power supply current, open-loop gain, gain-bandwidth product, slew rate, power-supply and common-mode rejection ratios. Bipolar transistor op amps with resistive collector load resistors for the input stage indicated the best radiation hardness

  15. Current trends in laser fusion driver and beam combination laser systems using stimulated Brillouin scattering phase conjugate mirrors for a fusion driver

    International Nuclear Information System (INIS)

    Laser facilities in the world have been developing flash-lamp-pumped ultrahigh-energy solid-state lasers for fusion research and high-repetition diode-pumped solid-state lasers to act as commercial fusion drivers. A commercial laser fusion driver requires a high-energy beam with a total energy of several megajoules per pulse in several nanoseconds with a ∼10-Hz repetition rate. However, current laser technologies have limitations in raising the beam energy when operating with a high repetition rate, which is necessary for a commercial fusion driver to function properly. The beam combination laser system, which that uses stimulated Brillouin scattering phase conjugate mirrors, is a promising candidate for a fusion driver because it can obtain both a high energy and a high repetition rate with separate amplifications. For the realization of the beam combination laser system, a self-phase control technique was proposed for the coherent beam combined output, and its principle was demonstrated experimentally.

  16. High-current Standing Wave Linac With Gyrocon Power Source

    CERN Document Server

    Karliner, M M; Makarov, I G; Nezhevenko, O A; Ostreiko, G N; Persov, B Z; Serdobintsev, G V

    2004-01-01

    A gyrocon together with high-voltage 1.5 MeV accelerator ELIT-3A represents a power generator at 430 MHz serving for linear electron accelerator pulse driving. The facility description and results of calorimetric measurements of ELIT-3A electron beam power and accelerated beam at the end of accelerator are presented in the paper. 2.2 amps of pulsed current have been obtained at electron energy of 20 MeV. The achieved energy conversion efficiency is about 55%.

  17. Non-linear current-voltage characteristics of NS-tunnel junctions prepared by focused ion beam induced deposition

    International Nuclear Information System (INIS)

    We used a focused Ga-ion beam and the precursor W(CO)6 -injected into a vacuum chamber nearby the focal area of the beam- to create tungsten containing superconducting deposits with a critical temperature of about 5.2 K. The deposits were fabricated onto oxidized aluminum contacts pre-patterned by UV-photolithography. I-V- and V-dI/dV- measurements have been performed between 0.3 K and 6 K using a He3-cryostat. For selected beam energies used during deposition the samples show Josephson-junction like behaviour or tunneling of quasiparticles for temperatures below the superconducting transition of aluminum at about 2 K. In the temperature range between the superconducting transitions of the two electrodes Andreev-reflection was observed.

  18. The NSCL electron beam ion trap for the reacceleration of rare isotopes coming to life: First extraction tests with a high-current electron gun

    International Nuclear Information System (INIS)

    NSCL is currently constructing the ReA3 reaccelerator, which will accelerate rare isotopes obtained from gas stopping of fast-fragment beams to energies of up to 3 MeV/u for uranium and higher for lighter ions. A high-current charge breeder, based on an electron beam ion trap (EBIT), has been chosen as the first step in the acceleration process, as it has the potential to efficiently produce highly charged ions in a single charge state. These ions are fed into a compact linear accelerator consisting of a radio frequency quadrupole structure and superconducting cavities. The NSCL EBIT has been fully designed with most of the parts constructed. The design concept of the EBIT and results from initial commissioning tests of the electron gun and collector with a temporary 0.4 T magnet are presented.

  19. Beam loading compensation for the NLC low frequency linacs

    International Nuclear Information System (INIS)

    The NLC low rf linacs are heavily loaded by a beam of about 130 ns in macropulse length (90 bunches) and a current up to 2.75 Amps. Beam loading voltage generates a large energy spread along the bunch train. This energy spread is critical for lattice design and, if not properly compensated, induces emittance growth and in turn lowers the luminosity of the machine. In this paper, the authors study the ΔF and ΔT beam loading compensation techniques for the NLC low rf linacs. They will apply these methods to the NLC low rf linacs to demonstrate the efficacy of these methods. Finally, they discuss a hybrid ΔT + ΔF method to improve the efficiency of beam loading compensation

  20. Expression profiles of antimicrobial peptides (AMPs) and their regulation by Relish

    Institute of Scientific and Technical Information of China (English)

    WANG Dongdong; LI Fuhua; LI Shihao; WEN Rong; XIANG Jianhai

    2012-01-01

    Antimicrobial peptides (AMPs),as key immune effectors,play important roles in the innate immune system of invertebrates.Different types of AMPs,including Penaeidin,Crustin,ALF (antilipopolysaccharide factor) have been identified in different penaeid shrimp; however,systematic analyses on the function of different AMPs in shrimp responsive to different types of bacteria are very limited.In this study,we analyzed the expression profiles of AMPs in the Chinese shrimps,Fenneropenaeus chinensis,simultaneously by real-time RT-PCR (reverse transcription-polymerase chain reaction) when shrimp were challenged with Micrococcus lysodeikticus (Gram-positive,G+) or Vibrio anguillarium (Gram-negative,G).Different AMPs showed different expression profiles when shrimp were injected with one type of bacterium,and one AMP also showed different expression profiles when shrimp were challenged with different bacteria.Furthermore,the expression of these AMPs showed temporal expression profiles,suggesting that different AMPs function coordinately in bacteria-infected shrimp.An RNA interference approach was used to study the function of the Relish transcription factor in regulating the transcription of different AM Ps.The current study showed that Relish could regulate the transcription of different AMPs in shrimp.Differential expression profiles of AMPs in shrimp injected with different types of bacteria indicated that a complicated antimicrobial response network existed in shrimp.These data contribute to our understanding of immunity in shrimp and may provide a strategy for the control of disease in shrimp.

  1. High energy high current neutral beam injector operation with single-stage and two-stage multiaperture extraction systems

    International Nuclear Information System (INIS)

    A three electrode extraction system, for 80 keV operation was developed, which was based on the standard triode concept, but takes advantage of the additional room between apertures necessary for water cooling, to give a pseudo-Pierce shape to the plasma electrode and thus produce beams with good optics. This system has been operated up to 40 A extracted ion beam at 80 keV energy. We have also, after these experiments, operated the injector with a two stage extraction system developed at Culham Laboratory and which was intended for J.E.T. injectors. Some significative results of the study (which cover over two years of experimental work) of these two different extraction systems are presented and discussed

  2. Pico amp measurement circuit with high system isolation

    International Nuclear Information System (INIS)

    An increase in sensitivity of 2000 can be achieved by modifying a Tektronics P6042 Hall Effect probe to accept 2000 turns as opposed to the standard single turn current input line. This increase in sensitivity coupled with a special self-zeroing amplifier allows the measurement of Pico-amps while maintaining high system isolation

  3. Bipolar power sources for the correction magnets of AmPS

    International Nuclear Information System (INIS)

    AmPS consists of many correction magnets which must provide the currents. These currents serve continuously between -3 Amp and +3 Amp. The adjusted current must be stable inside 0,1%. The copper resistance of magnet coils and their wires are ≤ 8 ohm and the self induction is 200 mH. An extended market research on power supplies has enabled the authors to decide to develop it themselves. This development has led to a module system with Bitbus control. (authors). 14 figs., 4 tabs

  4. Beam-Beam Effects

    OpenAIRE

    Herr, W; Pieloni, T.

    2016-01-01

    One of the most severe limitations in high-intensity particle colliders is the beam-beam interaction, i.e. the perturbation of the beams as they cross the opposing beams. This introduction to beam-beam effects concentrates on a description of the phenomena that are present in modern colliding beam facilities.

  5. Beam-Beam Effects

    CERN Document Server

    Herr, W

    2014-01-01

    One of the most severe limitations in high-intensity particle colliders is the beam-beam interaction, i.e. the perturbation of the beams as they cross the opposing beams. This introduction to beam-beam effects concentrates on a description of the phenomena that are present in modern colliding beam facilities.

  6. Comparative Analysis of Modeling a High-Current Relativistic Charged-Particle Beam in a Diode with Magnetic Insulation Using the Finite-Difference Method and the Large-Particle Method

    Science.gov (United States)

    Bogdanovich, B. Yu.; Nesterovich, A. V.; Sukhanova, L. A.; Khlestkov, Yu. A.

    2014-08-01

    Results of modeling of a high-current relativistic beam by the finite-difference method are compared with results obtained for a beam with the same parameters using the well-known KARAT code, which is based on the large-particle method. These two methods give similar results, which justifies the use of the finite-difference method for the numerical solution of the equations of motion describing the motion of the beam in its own and an external electromagnetic field.

  7. Detailed magnetic model simulations of the H- injection chicane magnets for the CERN PS Booster Upgrade, including eddy currents and influence on beam dynamics

    CERN Document Server

    Benedetto, E; Borburgh, J; Carli, C; Martini, M; Forte, V

    2014-01-01

    The CERN PS Booster will be upgraded with an H- injection system. The chicanemagnets for the injection bump ramp-down in 5 ms and generate eddy currents in the inconel vacuum chamber which perturb the homogeneity of the magnetic field. The multipolar field components are extracted from 3D OPERA simulations and are included in the lattice model. The -beating correction is computed all along the ramp and complete tracking simulations including space-charge are performed to evaluate the impact of these perturbations and correction on beam dynamics.

  8. Observations of ''effective'' transverse beam-size instabilities for a high current per bunch fill pattern in the APS storage ring

    International Nuclear Information System (INIS)

    The x-ray pinhole camera diagnostics on the Advanced Photon Source (APS) storage ring have recorded an effective transverse beam size instability during operations with a sextuplet plus 22 singlets fill pattern. These instabilities were not observed with the sextuplet plus 25 triplets fill pattern that has been the standard fill pattern in FY'98. The instability threshold is at 82-85 mA with positrons. The features include an increased average (few seconds) transverse size both horizontally and vertically for stored currents above the threshold with a correlated effect on the beam lifetime. The horizontal transverse emittance is 25-30% larger at 100 mA than below the threshold. There is a related horizontal beam centroid motion as well, but this does not explain the vertical size change nor the lifetime effect. Complementary data were also taken with the diagnostic undulator, and a similar threshold effect on divergence was observed. The cross-comparison of the data and possible mechanisms is presented

  9. Experimental study of the dependence of beam current on injection magnetic field in 6.4 GHz ECR ion source

    Indian Academy of Sciences (India)

    G S Taki; P R Sarma; D K Chakraborty; R K Bhandari; P K Ray

    2006-09-01

    The ion current from an electron cyclotron resonance (ECR) heavy ion source depends on the confining axial and radial magnetic fields. Some efforts were made by earlier workers to investigate magnetic field scaling on the performance of the ECR source. In order to study the dependence of the ion current on the injection magnetic field in the 6.4 GHz ECR source, we have measured the current by varying the peak injection field and have inferred that the variation of the current is exponential up to our maximum design injection field of 7.5 kG. An attempt has been made to understand this exponential nature on the basis of ion confinement time.

  10. Generating high-current monoenergetic proton beams by a circularly polarized laser pulse in the phase-stable acceleration regime.

    Science.gov (United States)

    Yan, X Q; Lin, C; Sheng, Z M; Guo, Z Y; Liu, B C; Lu, Y R; Fang, J X; Chen, J E

    2008-04-01

    A new ion acceleration method, namely, phase-stable acceleration, using circularly-polarized laser pulses is proposed. When the initial target density n(0) and thickness D satisfy a(L) approximately (n(0)/n(c))D/lambda(L) and D>l(s) with a(L), lambda(L), l(s), and n(c) the normalized laser amplitude, the laser wavelength in vacuum, the plasma skin depth, and the critical density of the incident laser pulse, respectively, a quasiequilibrium for the electrons is established by the light pressure and the space charge electrostatic field at the interacting front of the laser pulse. The ions within the skin depth of the laser pulse are synchronously accelerated and bunched by the electrostatic field, and thereby a high-intensity monoenergetic proton beam can be generated. The proton dynamics is investigated analytically and the results are verified by one- and two-dimensional particle-in-cell simulations. PMID:18517963

  11. Simple Laser-Driven, Metal Photocathodes as Cold, High Current Electron Sources

    OpenAIRE

    Saunders, Jimmy Dale

    1986-01-01

    Recent developments in excimer laser design have made near ultraviolet light intensities of several megawatts per square centimeter possible in unfocused beams. These advances and recent experiments indicate that high-current, simple-metal photoemissive electron guns are now feasible. Such guns should produce greater than 50 Amps per square centimeter of illuminated cathode surface. Additionally, these guns could operate at vacuums of 10"6 torr with no complicated system components inside ...

  12. Developement of a large proton accelerator for innovative researches; development of low energy high current beam transport system

    Energy Technology Data Exchange (ETDEWEB)

    Ko, In Soo; Namkung, Won; Cho, M. H.; Kim, K. N.; Kim, J. H.; Bae, Y. S.; Kim, Y.; Kim, K. H.; Shim, K. Y. [Pohang University of Science and Technology, Pohang (Korea)

    2001-04-01

    We have designed the beam transport system to connect the ion source and the RFQ. In this design, we have finalized the positions of solenoids and various beam diagnostic device. We have finalize the physical and mechanical designs of solenoids, and these designs are already adopted to produce the actual solenoids. We have also studied about EPICS, Experimental Physics and Industrial Control System, to control a stepper motor as a tuner of the RFQ designed for KOMACEPICS is a real time control system for a large scale system such as accelerators and tokamaks. The purpose of this thesis is to establish a test system based on the EPICS. A Sun UtraSPARC 5 workstation is used as the Operator Interface(OPI) console, and a VME chassis contained a Motorola MVME162 single board computer is used as the Input/Output Controller(IOC). A stepper motor controller is connected to the IOC via an RS-232C as a field bus. The EPICS base, extensions, and the real time OS vxWorks are installed on the workstation. The real time OS image can be downloaded to the IOC via the FTP when the test station is started. We have installed an IOC application as a device and driver support layer for the serial communication with an RS-232C on the workstation. We have designed the IOC database configuration files and a graphic user interface style OPI panel which was programmed by the MEDM. With this OPI, we can control the stepper motor using EPICS. 17 refs., 33 figs., 9 tabs. (Author)

  13. Observation of Muon Neutrino Charged Current Events in an Off-Axis Horn-Focused Neutrino Beam Using the NOvA Prototype Detector

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, Enrique Arrieta [Michigan State Univ., East Lansing, MI (United States)

    2014-01-01

    The NOνA is a long base-line neutrino oscillation experiment. It will study the oscillations between muon and electron neutrinos through the Earth. NOνA consists of two detectors separated by 810 km. Each detector will measure the electron neutrino content of the neutrino (NuMI) beam. Differences between the measurements will reveal details about the oscillation channel. The NOνA collaboration built a prototype detector on the surface at Fermilab in order to develop calibration, simulation, and reconstruction tools, using real data. This 220 ton detector is 110 mrad off the NuMI beam axis. This off-axis location allows the observation of neutrino interactions with energies around 2 GeV, where neutrinos come predominantly from charged kaon decays. During the period between October 2011 and April 2012, the prototype detector collected neutrino data from 1.67 × 1020 protons on target delivered by the NuMI beam. This analysis selected a number of candidate charged current muon neutrino events from the prototype data, which is 30% lower than predicted by the NOνA Monte Carlo simulation. The analysis suggests that the discrepancy comes from an over estimation of the neutrino flux in the Monte Carlo simulation, and in particular, from neutrinos generated in charged kaon decays. The ratio of measured divided by the simulated flux of muon neutrinos coming from charged kaon decays is: 0.70+0.108 -0.094. The NOνA collaboration may use the findings of this analysis to introduce a more accurate prediction of the neutrino flux produced by the NuMI beam in future Monte Carlo simulations.

  14. Optimizing 50kV hydrogen diagnostic neutral beam performance for active spectroscopy in MST

    Science.gov (United States)

    Feng, X.; Boguski, J.; Craig, D.; den Hartog, D. J.; Munaretto, S.; Nornberg, M. D.; Olivia, S.

    2015-11-01

    The 50 kV hydrogen diagnostic neutral beam on MST provides local measurements of impurity ion emission through charge exchange recombination spectroscopy (CHERS) and of core-localized magnetic field through the motional Stark effect (MSE). The beam, which was designed to provide 5A of neutral current at 50 kV to meet these needs, is currently on a test stand to accommodate diagnosis, in order to increase the reliability of beam formation, sustain a steady current of 5 amps for 20ms, and optimize the primary energy fraction. The reliability of arc formation was increased from 40% to 80% success rate with increase of cathode gas pressure from 150kPa to 200kPa, and the stability of the arc current is improved with a decrease of the insulation magnetic field. A calorimeter with 5 thermocouples is installed to measure the horizontal and vertical beam profiles as well as beam divergence. Beam energy components are quantified through Doppler-shift spectroscopy. Preliminary simulation results of the beam using the ALCBEAM code as well as a description of how changes to the beam performance can affect CHERS and MSE measurements are presented. This work is supported by the U.S. DOE.

  15. Improvement of the 400 kV linac electron source of AmPS

    International Nuclear Information System (INIS)

    The installation of the 900 MeV Amsterdam Pulse Stretcher is nearly completed and its commissioning will start Spring 1992. The existing linac MEA will inject electrons in the AmPS ring. The linacs peak current will be increased from 20 to 80 mA. This requires modification of the 400 kV low emittance gun which now will deliver a peak current of maximum 400 mA instead of 100 mA at a pulse width of 2.1 μsec. The fourfold increase of the peakcurrent is obtained by doubling both the gun perveance (new gun part) and the pulsed extractor voltage. After chopping and pre-bunching more than 80 mA will be available for acceleration in MEA. To obtain optimum beam quality over this increased current range the hot deck electronics, operating at -400 kV, has been exchanged by a state of the art fast high voltage FET switching supply. The increased space charge forces in the beam require stronger electro-static focusing in the first electrostatic gap to define the beam diameter at the gun exit. This is accomplished with a 25 kV controlled power supply. A build in microprocessor, coupled to the local computer by optical fibers, is used to monitor and control the gun parameters. The 5kV gun extractor voltage pulse shape can be monitored by means of an analog fibre transducer with build in calibration. Finally, in order to improve the energy stability of the accelerated electrons a serial electron-tube stabilizer was added to the 400 kV DC power supply. A supply stability of 2. 10-5 has been achieved. (author). 4 refs.; 6 figs

  16. Ion beam diagnosis

    International Nuclear Information System (INIS)

    This report is an introduction to ion beam diagnosis. After a short description of the most important ion beam parameters measurements of the beam current by means of Faraday cups, calorimetry, and beam current transformers and measurements of the beam profile by means of viewing screens, profile grids and scanning devices, and residual gas ionization monitors are described. Finally measurements in the transverse and longitudinal phase space are considered. (HSI)

  17. Nanoelectronic devices--resonant tunnelling diodes grown on InP substrates by molecular beam epitaxy with peak to valley current ratio of 17 at room temperature

    Institute of Scientific and Technical Information of China (English)

    Zhang Yang; Zeng Yi-Ping; Ma Long; Wang Bao-Qiang; Zhu Zhan-Ping; Wang Liang-Chen; Yang Fu-Hua

    2006-01-01

    This paper reports that InAs/In0.53Ga0.47As/AlAs resonant tunnelling diodes have been grown on InP substrates by molecular beam epitaxy. Peak to valley current ratio of these devices is 17 at 300K. A peak current density of 3kA/cm2 has been obtained for diodes with AlAs barriers of ten monolayers, and an In0.53Ga0.47As well of eight monolayers with four monolayers of InAs insert layer. The effects of growth interruption for smoothing potential barrier interfaces have been investigated by high resolution transmission electron microscope.

  18. Measurement of the νμ charged current quasielastic cross section on carbon with the T2K on-axis neutrino beam

    Science.gov (United States)

    Abe, K.; Adam, J.; Aihara, H.; Andreopoulos, C.; Aoki, S.; Ariga, A.; Assylbekov, S.; Autiero, D.; Barbi, M.; Barker, G. J.; Barr, G.; Bartet-Friburg, P.; Bass, M.; Batkiewicz, M.; Bay, F.; Berardi, V.; Berger, B. E.; Berkman, S.; Bhadra, S.; Blaszczyk, F. d. M.; Blondel, A.; Bolognesi, S.; Bordoni, S.; Boyd, S. B.; Brailsford, D.; Bravar, A.; Bronner, C.; Buchanan, N.; Calland, R. G.; Caravaca Rodríguez, J.; Cartwright, S. L.; Castillo, R.; Catanesi, M. G.; Cervera, A.; Cherdack, D.; Chikuma, N.; Christodoulou, G.; Clifton, A.; Coleman, J.; Coleman, S. J.; Collazuol, G.; Connolly, K.; Cremonesi, L.; Dabrowska, A.; Danko, I.; Das, R.; Davis, S.; de Perio, P.; De Rosa, G.; Dealtry, T.; Dennis, S. R.; Densham, C.; Dewhurst, D.; Di Lodovico, F.; Di Luise, S.; Dolan, S.; Drapier, O.; Duffy, K.; Dumarchez, J.; Dytman, S.; Dziewiecki, M.; Emery-Schrenk, S.; Ereditato, A.; Escudero, L.; Ferchichi, C.; Feusels, T.; Finch, A. J.; Fiorentini, G. A.; Friend, M.; Fujii, Y.; Fukuda, Y.; Furmanski, A. P.; Galymov, V.; Garcia, A.; Giffin, S.; Giganti, C.; Gilje, K.; Goeldi, D.; Golan, T.; Gonin, M.; Grant, N.; Gudin, D.; Hadley, D. R.; Haegel, L.; Haesler, A.; Haigh, M. D.; Hamilton, P.; Hansen, D.; Hara, T.; Hartz, M.; Hasegawa, T.; Hastings, N. C.; Hayashino, T.; Hayato, Y.; Hearty, C.; Helmer, R. L.; Hierholzer, M.; Hignight, J.; Hillairet, A.; Himmel, A.; Hiraki, T.; Hirota, S.; Holeczek, J.; Horikawa, S.; Hosomi, F.; Huang, K.; Ichikawa, A. K.; Ieki, K.; Ieva, M.; Ikeda, M.; Imber, J.; Insler, J.; Irvine, T. J.; Ishida, T.; Ishii, T.; Iwai, E.; Iwamoto, K.; Iyogi, K.; Izmaylov, A.; Jacob, A.; Jamieson, B.; Jiang, M.; Johnson, S.; Jo, J. H.; Jonsson, P.; Jung, C. K.; Kabirnezhad, M.; Kaboth, A. C.; Kajita, T.; Kakuno, H.; Kameda, J.; Kanazawa, Y.; Karlen, D.; Karpikov, I.; Katori, T.; Kearns, E.; Khabibullin, M.; Khotjantsev, A.; Kielczewska, D.; Kikawa, T.; Kilinski, A.; Kim, J.; King, S.; Kisiel, J.; Kitching, P.; Kobayashi, T.; Koch, L.; Koga, T.; Kolaceke, A.; Konaka, A.; Kopylov, A.; Kormos, L. L.; Korzenev, A.; Koshio, Y.; Kropp, W.; Kubo, H.; Kudenko, Y.; Kurjata, R.; Kutter, T.; Lagoda, J.; Lamont, I.; Larkin, E.; Laveder, M.; Lawe, M.; Lazos, M.; Lindner, T.; Lister, C.; Litchfield, R. P.; Longhin, A.; Lopez, J. P.; Ludovici, L.; Magaletti, L.; Mahn, K.; Malek, M.; Manly, S.; Marino, A. D.; Marteau, J.; Martin, J. F.; Martins, P.; Martynenko, S.; Maruyama, T.; Matveev, V.; Mavrokoridis, K.; Mazzucato, E.; McCarthy, M.; McCauley, N.; McFarland, K. S.; McGrew, C.; Mefodiev, A.; Metelko, C.; Mezzetto, M.; Mijakowski, P.; Miller, C. A.; Minamino, A.; Mineev, O.; Missert, A.; Miura, M.; Moriyama, S.; Mueller, Th. A.; Murakami, A.; Murdoch, M.; Murphy, S.; Myslik, J.; Nakadaira, T.; Nakahata, M.; Nakamura, K. G.; Nakamura, K.; Nakayama, S.; Nakaya, T.; Nakayoshi, K.; Nantais, C.; Nielsen, C.; Nirkko, M.; Nishikawa, K.; Nishimura, Y.; Nowak, J.; O'Keeffe, H. M.; Ohta, R.; Okumura, K.; Okusawa, T.; Oryszczak, W.; Oser, S. M.; Ovsyannikova, T.; Owen, R. A.; Oyama, Y.; Palladino, V.; Palomino, J. L.; Paolone, V.; Payne, D.; Perevozchikov, O.; Perkin, J. D.; Petrov, Y.; Pickard, L.; Pinzon Guerra, E. S.; Pistillo, C.; Plonski, P.; Poplawska, E.; Popov, B.; Posiadala-Zezula, M.; Poutissou, J.-M.; Poutissou, R.; Przewlocki, P.; Quilain, B.; Radicioni, E.; Ratoff, P. N.; Ravonel, M.; Rayner, M. A. M.; Redij, A.; Reeves, M.; Reinherz-Aronis, E.; Riccio, C.; Rodrigues, P. A.; Rojas, P.; Rondio, E.; Roth, S.; Rubbia, A.; Ruterbories, D.; Rychter, A.; Sacco, R.; Sakashita, K.; Sánchez, F.; Sato, F.; Scantamburlo, E.; Scholberg, K.; Schoppmann, S.; Schwehr, J.; Scott, M.; Seiya, Y.; Sekiguchi, T.; Sekiya, H.; Sgalaberna, D.; Shah, R.; Shaker, F.; Shaw, D.; Shiozawa, M.; Short, S.; Shustrov, Y.; Sinclair, P.; Smith, B.; Smy, M.; Sobczyk, J. T.; Sobel, H.; Sorel, M.; Southwell, L.; Stamoulis, P.; Steinmann, J.; Still, B.; Suda, Y.; Suzuki, A.; Suzuki, K.; Suzuki, S. Y.; Suzuki, Y.; Tacik, R.; Tada, M.; Takahashi, S.; Takeda, A.; Takeuchi, Y.; Tanaka, H. K.; Tanaka, H. A.; Tanaka, M. M.; Terhorst, D.; Terri, R.; Thompson, L. F.; Thorley, A.; Tobayama, S.; Toki, W.; Tomura, T.; Totsuka, Y.; Touramanis, C.; Tsukamoto, T.; Tzanov, M.; Uchida, Y.; Vacheret, A.; Vagins, M.; Vasseur, G.; Wachala, T.; Wakamatsu, K.; Walter, C. W.; Wark, D.; Warzycha, W.; Wascko, M. O.; Weber, A.; Wendell, R.; Wilkes, R. J.; Wilking, M. J.; Wilkinson, C.; Williamson, Z.; Wilson, J. R.; Wilson, R. J.; Wongjirad, T.; Yamada, Y.; Yamamoto, K.; Yanagisawa, C.; Yano, T.; Yen, S.; Yershov, N.; Yokoyama, M.; Yoo, J.; Yoshida, K.; Yuan, T.; Yu, M.; Zalewska, A.; Zalipska, J.; Zambelli, L.; Zaremba, K.; Ziembicki, M.; Zimmerman, E. D.; Zito, M.; Żmuda, J.; T2K Collaboration

    2015-06-01

    We report a measurement of the νμ charged current quasielastic cross-sections on carbon in the T2K on-axis neutrino beam. The measured charged current quasielastic cross-sections on carbon at mean neutrino energies of 1.94 GeV and 0.93 GeV are (11.95 ±0.19 (stat)-1.47+1.82(syst))×1 0-39 cm2/neutron , and (10.64 ±0.37 (stat)-1.65+2.03(syst))×1 0-39 cm2/neutron , respectively. These results agree well with the predictions of neutrino interaction models. In addition, we investigated the effects of the nuclear model and the multi-nucleon interaction.

  19. 10 cm range two-resonator electron accelerator with a bridge circuit of power supply and deep control of energy and beam current

    International Nuclear Information System (INIS)

    Description and nominal parameters of a resonator accelerator of vaciable energy from tens keV to 1 MeV and pulse current from units to hundreds of milliamperes for using in semiconductor defectoscopy and simulation of electrostatic shields under earth conditions are presented. An accelerating system consists of two 10 cm-wave length resonators supplied with HF power through three-decibel directional coupler. A serial autogenerator-1.3 MW pulse power magnetron is a power supply. A vacuum system contains two small zeolite pumps and the HOPD-100 electrocharge pump. An electron gun with the Trenyeva geometry producing 40 keV electron beam and 7A pulse current serves an injector. Control panel is used for distance accelerator control

  20. Measurement of high-Q2 neutral current deep inelastic e-p scattering cross sections with a longitudinally polarised electron beam at HERA

    International Nuclear Information System (INIS)

    Measurements of the neutral current cross sections for deep inelastic scattering in e-p collisions at HERA with a longitudinally polarised electron beam are presented. The single-differential cross-sections dσ/dQ2, dσ/dx and dσ/dy and the double-differential cross sections in Q2 and x are measured in the kinematic region y 2 > 185GeV2 for both positively and negatively polarised electron beams and for each polarisation state separately. The measurements are based on an integrated luminosity of 169.9 pb-1 taken with the ZEUS detector in 2005 and 2006 at a centre-of-mass energy of 318GeV. The structure functions xF3 and xF3γZ are determined by combining the e-p results presented in this paper with previously measured e+p neutral current data. The asymmetry parameter A- is used to demonstrate the parity violating effects of electroweak interactions at large spacelike photon virtuality. The measurements agree well with the predictions of the Standard Model. (orig.)

  1. Measurement of high-Q{sup 2} neutral current deep inelastic e{sup -}p scattering cross sections with a longitudinally polarised electron beam at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Lab., Argonne, IL (US)] (and others)

    2008-12-15

    Measurements of the neutral current cross sections for deep inelastic scattering in e{sup -}p collisions at HERA with a longitudinally polarised electron beam are presented. The single-differential cross-sections d{sigma}/dQ{sup 2}, d{sigma}/dx and d{sigma}/dy and the double-differential cross sections in Q{sup 2} and x are measured in the kinematic region y < 0.9 and Q{sup 2} > 185GeV{sup 2} for both positively and negatively polarised electron beams and for each polarisation state separately. The measurements are based on an integrated luminosity of 169.9 pb{sup -1} taken with the ZEUS detector in 2005 and 2006 at a centre-of-mass energy of 318GeV. The structure functions xF{sub 3} and xF{sub 3}{sup {gamma}}{sup Z} are determined by combining the e{sup -}p results presented in this paper with previously measured e{sup +}p neutral current data. The asymmetry parameter A{sup -} is used to demonstrate the parity violating effects of electroweak interactions at large spacelike photon virtuality. The measurements agree well with the predictions of the Standard Model. (orig.)

  2. Measurement of high-Q{sup 2} neutral current deep inelastic e{sup +}p scattering cross sections with a longitudinally polarised positron beam at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max Planck Institute for Physics, Munich (Germany); Abt, I. [Max Planck Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (Poland). Faculty of Physics and Applied Computer Science] [and others; Collaboration: ZEUS Collaboration

    2012-08-15

    Measurements of neutral current cross sections for deep inelastic scattering in e{sup +}p collisions at HERA with a longitudinally polarised positron beam are presented. The single-differential cross-sections d{sigma}/dQ{sup 2}, d{sigma}/dx and d{sigma}/dy and the reduced cross-section {sigma} were measured in the kinematic region Q{sup 2}>185 GeV{sup 2} and y<0.9, where Q{sup 2} is the four-momentum transfer squared, x the Bjorken scaling variable, and y the inelasticity of the interaction. The measurements were performed separately for positively and negatively polarised positron beams. The measurements are based on an integrated luminosity of 135.5 pb{sup -1} collected with the ZEUS detector in 2006 and 2007 at a centre-of-mass energy of 318 GeV. The structure functions F{sub 3} and F{sup {gamma}Z}{sub 3} were determined by combining the e{sup +}p results presented in this paper with previously published e{sup -}p neutral current results. The asymmetry parameter A{sup +} is used to demonstrate the parity violation predicted in electroweak interactions. The measurements are well described by the predictions of the Standard Model.

  3. Measurement of high-Q2 neutral current deep inelastic e+p scattering cross sections with a longitudinally polarised positron beam at HERA

    International Nuclear Information System (INIS)

    Measurements of neutral current cross sections for deep inelastic scattering in e+p collisions at HERA with a longitudinally polarised positron beam are presented. The single-differential cross-sections dσ/dQ2, dσ/dx and dσ/dy and the reduced cross-section σ were measured in the kinematic region Q2>185 GeV2 and y2 is the four-momentum transfer squared, x the Bjorken scaling variable, and y the inelasticity of the interaction. The measurements were performed separately for positively and negatively polarised positron beams. The measurements are based on an integrated luminosity of 135.5 pb-1 collected with the ZEUS detector in 2006 and 2007 at a centre-of-mass energy of 318 GeV. The structure functions F3 and FγZ3 were determined by combining the e+p results presented in this paper with previously published e-p neutral current results. The asymmetry parameter A+ is used to demonstrate the parity violation predicted in electroweak interactions. The measurements are well described by the predictions of the Standard Model.

  4. Detection and occurrence of plasmid-mediated AmpC in highly resistant gram-negative Rods

    OpenAIRE

    Reuland, E. Ascelijn; Hays, John; Jongh, Denise; Abdelrehim, Eman; Willemsen, Ina; Kluytmans, Jan; Savelkoul, Paul; Vandenbroucke-Grauls, Christina; Naiemi, Nashwan Al

    2014-01-01

    textabstractObjectives: The aim of this study was to compare the current screening methods and to evaluate confirmation tests for phenotypic plasmidal AmpC (pAmpC) detection. Methods: For this evaluation we used 503 Enterobacteriaceae from 18 Dutch hospitals and 21 isolates previously confirmed to be pAmpC positive. All isolates were divided into three groups: isolates with 1) reduced susceptibility to ceftazidime and/or cefotaxime; 2) reduced susceptibility to cefoxitin; 3) reduced susceptib...

  5. Measurements of the neutral current e{sup {+-}}p cross sections using longitudinally polarised lepton beams at HERA II

    Energy Technology Data Exchange (ETDEWEB)

    Nikiforov, A.

    2007-01-18

    This thesis presents inclusive e{sup {+-}}p single and double differential cross sections for neutral current deep inelastic scattering measured as functions of the four-momentum transfer squared Q{sup 2} and the Bjorken variable x in interactions of longitudinally polarised leptons with unpolarised protons using the H1 detector at HERA II. An overview of the phenomenology of deep inelastic scattering is given and the experimental apparatus as well as the measurement and analysis procedures are described. The analysis is based on e{sup +}p data taken in 2003-04 and e{sup -}p data taken in 2005 at a centre-of-mass energy of {radical}(s)=318 GeV, with integrated luminosities of 47.6 pb{sup -1} and 98.4 pb{sup -1} for the e{sup +}p and e{sup -}p samples, respectively. The cross sections are measured in the range of 200current interactions and to determine the structure function xF{sub 3}. The new HERA II data are combined together with previously published data from HERA I to determine the structure function xF{sub 3} with improved precision. Furthermore, this measurement is combined with the corresponding ZEUS measurement to provide the most accurate measurement of the interference structure function xF{sup {gamma}}{sup Z}{sub 3}, which is sensitive to the valence quark distributions down to low values of x. The data on polarised cross section asymmetries A{sup {+-}} are also combined with the ZEUS data. This leads to the first observation of parity violation in neutral current e{sup {+-}}p scattering at distances down to 10{sup -18} m. The data are well described by the Standard Model predictions. (orig.)

  6. Phase-space holes due to electron and ion beams accelerated by a current-driven potential ramp

    Directory of Open Access Journals (Sweden)

    M. V. Goldman

    2003-01-01

    Full Text Available One-dimensional open-boundary simulations have been carried out in a current-carrying plasma seeded with a neutral density depression and with no initial electric field. These simulations show the development of a variety of nonlinear localized electric field structures: double layers (unipolar localized fields, fast electron phase-space holes (bipolar fields moving in the direction of electrons accelerated by the double layer and trains of slow alternating electron and ion phase-space holes (wave-like fields moving in the direction of ions accelerated by the double layer. The principal new result in this paper is to show by means of a linear stability analysis that the slow-moving trains of electron and ion holes are likely to be the result of saturation via trapping of a kinetic-Buneman instability driven by the interaction of accelerated ions with unaccelerated electrons.

  7. Measurements of the neutral current e±p cross sections using longitudinally polarised lepton beams at HERA II

    International Nuclear Information System (INIS)

    This thesis presents inclusive e±p single and double differential cross sections for neutral current deep inelastic scattering measured as functions of the four-momentum transfer squared Q2 and the Bjorken variable x in interactions of longitudinally polarised leptons with unpolarised protons using the H1 detector at HERA II. An overview of the phenomenology of deep inelastic scattering is given and the experimental apparatus as well as the measurement and analysis procedures are described. The analysis is based on e+p data taken in 2003-04 and e-p data taken in 2005 at a centre-of-mass energy of √(s)=318 GeV, with integrated luminosities of 47.6 pb-1 and 98.4 pb-1 for the e+p and e-p samples, respectively. The cross sections are measured in the range of 20022 and 0.00323. The new HERA II data are combined together with previously published data from HERA I to determine the structure function xF3 with improved precision. Furthermore, this measurement is combined with the corresponding ZEUS measurement to provide the most accurate measurement of the interference structure function xFγZ3, which is sensitive to the valence quark distributions down to low values of x. The data on polarised cross section asymmetries A± are also combined with the ZEUS data. This leads to the first observation of parity violation in neutral current e±p scattering at distances down to 10-18 m. The data are well described by the Standard Model predictions. (orig.)

  8. The AzTEC Mathematics Project (AMP).

    Science.gov (United States)

    Johnson, Gae R.

    The AzTEC Mathematics Project (AMP) is a statewide partnership among Arizona's Regents universities and state community colleges, partner school districts, and economic communities. AzTec is committed to preparing highly qualified K-12 mathematics and science teachers. AMP targeted Native American teachers and teachers of Native American students…

  9. Improvement of the 400 kV linac electron source of AmPS

    International Nuclear Information System (INIS)

    An existing linac (MEA) injects electrons into the Amsterdam Pulse Stretcher (AmPS) ring. The linac's peak current increases from 20 to 80 mA. This requires the modification of the 400 kV low emittance gun. The fourfold increase of the peak current is obtained by doubling both the gun perveance (new gun part) and the pulsed extractor voltage. To obtain optimum beam quality over this increased current range, the hot deck electronics has been exchanged by a fast high voltage FET switching supply. A built-in microprocessor, coupled to the local computer by optical fibers, is used to monitor and control the gun parameters. The 5 kV gun extractor voltage pulse shape can be monitored by means of an analog fibre transducer with build in calibration. Finally, in order to improve the energy stability of the accelerated electrons, a serial electron-tube stabilizer was added to the 400 kV DC power supply. (K.A.) 4 refs.; 6 figs

  10. Bias dependence and correlation of the cathodoluminescence and electron beam induced current from an InGaN/GaN light emitting diode

    International Nuclear Information System (INIS)

    Micron-scale mapping has been employed to study a contacted InGaN/GaN LED using combined electroluminescence (EL), cathodoluminescence (CL), and electron beam induced current (EBIC). Correlations between parameters, such as the EBIC and CL intensity, were studied as a function of applied bias. The CL and EBIC maps reveal small areas, 2–10 μm in size, which have increased nonradiative recombination rate and/or a lower conductivity. The CL emission from these spots is blue shifted, by 30–40 meV. Increasing the reverse bias causes the size of the spots to decrease, due to competition between in-plane diffusion and drift in the growth direction. EL mapping shows large bright areas (∼100 μm) which also have increased EBIC, indicating domains of increased conductivity in the p and/or n-GaN.

  11. Temperature-sensitive junction transformations for mid-wavelength HgCdTe photovoltaic infrared detector arrays by laser beam induced current microscope

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Weicheng [College of Photoelectric Science and Engineering, National University of Defense Technology, Changsha, Hunan 410073 (China); National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Hu, Weida, E-mail: wdhu@mail.sitp.ac.cn; Lin, Tie; Yin, Fei; Zhang, Bo; Chen, Xiaoshuang; Lu, Wei [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Cheng, Xiang' ai, E-mail: xiang-ai-cheng@126.com; Wang, Rui [College of Photoelectric Science and Engineering, National University of Defense Technology, Changsha, Hunan 410073 (China)

    2014-11-10

    In this paper, we report on the disappearance of the photosensitive area extension effect and the unusual temperature dependence of junction transformation for mid-wavelength, n-on-p HgCdTe photovoltaic infrared detector arrays. The n-type region is formed by B{sup +} ion implantation on Hg-vacancy-doped p-type HgCdTe. Junction transformations under different temperatures are visually captured by a laser beam induced current microscope. A physical model of temperature dependence on junction transformation is proposed and demonstrated by using numerical simulations. It is shown that Hg-interstitial diffusion and temperature activated defects jointly lead to the p-n junction transformation dependence on temperature, and the weaker mixed conduction compared with long-wavelength HgCdTe photodiode contributes to the disappearance of the photosensitive area extension effect in mid-wavelength HgCdTe infrared detector arrays.

  12. Cross-sectional analysis of the graded microstructure in an AISI D2-steel treated with low energy high-current pulsed electron beam

    International Nuclear Information System (INIS)

    A detailed analysis from cross-section of the rapidly solidified layer of a steel formed by low energy high-current pulsed electron beam (LEHCPEB) treatment has been successfully carried out. The results of electron backscattering diffraction (EBSD) measurements revealed that the microstructures and phase components vary dramatically through the melted layer and the heat-affected zone. The exact nature of such a graded structure also changes with the number of pulses. The phase transformation paths vary at different depth and different areas (close to or far away from the carbides). They are determined both by (i) the temperature gradients and (ii) the composition gradients in the surface layers induced by the LEHCPEB treatment.

  13. Model for Electron-Beam-Induced Current Analysis of mc-Si Addressing Defect Contrast Behavior in Heavily Contaminated PV Material: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Guthrey, H.; Gorman, B.; Al-Jassim, M.

    2012-06-01

    Much work has been done to correlate electron-beam-induced current (EBIC) contrast behavior of extended defects with the character and degree of impurity decoration. However, existing models fail to account for recently observed contrast behavior of defects in heavily contaminated mc-Si PV cells. We have observed large increases in defect contrast with decreasing temperature for all electrically active defects, regardless of their initial contrast signatures at ambient temperature. This negates the usefulness of the existing models in identifying defect character and levels of impurity decoration based on the temperature dependence of the contrast behavior. By considering the interactions of transition metal impurities with the silicon lattice and extended defects, we attempt to provide an explanation for these observations. Our findings will enhance the ability of the PV community to understand and mitigate the effects of these types of defects as the adoption of increasingly lower purity feedstocks for mc-Si PV production continues.

  14. Temperature-sensitive junction transformations for mid-wavelength HgCdTe photovoltaic infrared detector arrays by laser beam induced current microscope

    International Nuclear Information System (INIS)

    In this paper, we report on the disappearance of the photosensitive area extension effect and the unusual temperature dependence of junction transformation for mid-wavelength, n-on-p HgCdTe photovoltaic infrared detector arrays. The n-type region is formed by B+ ion implantation on Hg-vacancy-doped p-type HgCdTe. Junction transformations under different temperatures are visually captured by a laser beam induced current microscope. A physical model of temperature dependence on junction transformation is proposed and demonstrated by using numerical simulations. It is shown that Hg-interstitial diffusion and temperature activated defects jointly lead to the p-n junction transformation dependence on temperature, and the weaker mixed conduction compared with long-wavelength HgCdTe photodiode contributes to the disappearance of the photosensitive area extension effect in mid-wavelength HgCdTe infrared detector arrays

  15. Novel signal inversion of laser beam induced current for femtosecond-laser-drilling-induced junction on vacancy-doped p-type HgCdTe

    International Nuclear Information System (INIS)

    In this paper, experimental results of temperature-dependent signal inversion of laser beam induced current (LBIC) for femtosecond-laser-drilling-induced junction on vacancy-doped p-type HgCdTe are reported. LBIC characterization shows that the traps induced by femtosecond laser drilling are sensitive to temperature. Theoretical models for trap-related p-n junction transformation are proposed and demonstrated using numerical simulations. The simulations are in good agreement with the experimental results. The effects of traps and mixed conduction are possibly the main reasons that result in the novel signal inversion of LBIC microscope at room temperature. The research results provide a theoretical guide for practical applications of large-scale array HgCdTe infrared photovoltaic detectors formed by femtosecond laser drilling, which may act as a potential new method for fabricating HgCdTe photodiodes.

  16. Annealing of defect density and excess currents in Si-based tunnel diodes grown by low-temperature molecular-beam epitaxy

    International Nuclear Information System (INIS)

    Deep-level transient spectroscopy (DLTS) measurements were performed in order to investigate the effects of post-growth heat treatment on deep level defects in Si layers grown by low-temperature molecular-beam epitaxy (LT-MBE) at 320 deg. C. In the LT-MBE as-grown samples, two dominant divacancy-related complex defects, of which the possible origins are suggested as P-V (E center)+V-V (0/-) and V-V (-2/-) and others, were observed in P-doped n layers. When the as-grown samples were annealed at 700, 800, and 900 deg. C for 60 s by rapid thermal annealing, the total density of defects were decreased without generating other defects and most defects were annihilated at 900 deg. C. This study also compared the DLTS trends with performance of Si-based resonant interband tunnel diodes (RITDs) in terms of peak current density, valley current density, and peak-to-valley current ratio, which are closely related to the deep-level defects. The active regions of the RITDs were grown at the same substrate growth temperature and annealed at similar temperatures used in this DLTS study

  17. Multi-beam injector development at LBL

    International Nuclear Information System (INIS)

    LBL is developing a multi-beam injector that will be used for scaled accelerator experiments related to Heavy Ion Fusion. The device will produce sixteen 0.5 Amp beams of C+ at 2 MeV energy. The carbon arc source has been developed to the point where the emittance is within a factor of four of the design target. Modelling of the source behavior to find ways to reduce the emittance is discussed. Source lifetime and reliability is also of paramount importance to us and data regarding the lifetime and failure modes of different source configurations is discussed. One half of the accelerating column has been constructed and tested at high voltage. One beam experiments in this half column are underway. The second half of the column is being built and the transition 2 MV experiments should begin soon. In addition to beam and source performance we also discuss the controls for the injector and the electronics associated with the source and current injection. 3 refs., 2 figs

  18. Evaluation of Screening Methods To Detect Plasmid-Mediated AmpC in Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis▿

    OpenAIRE

    Tan, Thean Yen; Ng, Lily Siew Yong; He, Jie; Koh, Tse Hsien; Hsu, Li Yang

    2008-01-01

    There are currently no standardized phenotypic methods for the screening and detection of AmpC enzymes. This study aimed to evaluate different methods to detect AmpC enzymes in Escherichia coli, Klebsiella spp., and Proteus spp., comparing the results from two disk-based methods and an agar dilution method. AmpC activity was determined for 255 clinical isolates by use of a three-dimensional enzyme assay combined with a multiplex PCR assay for plasmid-borne ampC genes. These results were compa...

  19. Emittance of short-pulsed high-current ion beams formed from the plasma of the electron cyclotron resonance discharge sustained by high-power millimeter-wave gyrotron radiation

    Science.gov (United States)

    Razin, S.; Zorin, V.; Izotov, I.; Sidorov, A.; Skalyga, V.

    2014-02-01

    We present experimental results on measuring the emittance of short-pulsed (≤100 μs) high-current (80-100 mA) ion beams of heavy gases (Nitrogen, Argon) formed from a dense plasma of an ECR source of multiply charged ions (MCI) with quasi-gas-dynamic mode of plasma confinement in a magnetic trap of simple mirror configuration. The discharge was created by a high-power (90 kW) pulsed radiation of a 37.5-GHz gyrotron. The normalized emittance of generated ion beams of 100 mA current was (1.2-1.3) π mm mrad (70% of ions in the beams). Comparing these results with those obtained using a cusp magnetic trap, it was concluded that the structure of the trap magnetic field lines does not exert a decisive influence on the emittance of ion beams in the gas-dynamic ECR source of MCI.

  20. Design of inductively detuned RF extraction cavities for the Relativistic Klystron Two Beam Accelerator

    International Nuclear Information System (INIS)

    An inductively detuned traveling wave cavity for the Relativistic Klystron Two Beam Accelerator expected to extract high RF power at 11. 424 GHz for the 1 TeV Center of Mass Next Linear Collider has been designed. Longitudinal beam dynamics studies led to the following requirements on cavity design: (a) Extraction of 360 MW of RF power with RF component of the current being 1.15 kAmps at 11.424 GHz, (b) Inductively detuned traveling wave cavity with wave phase velocity equal to 4/3 the speed of light, (c) Output cavity with appropriate Qext and eigenfrequency for proper matching. Furthermore, transverse beam dynamics require low shunt impedances to avoid the beam break-up instability. We describe the design effort to meet these criteria based on frequency-domain and time-domain computations using 2D- and 3D- electromagnetic codes

  1. Producing nano-grained and Al-enriched surface microstructure on AZ91 magnesium alloy by high current pulsed electron beam treatment

    Science.gov (United States)

    Hao, Shengzhi; Li, Mincai

    2016-05-01

    Surface treatment of AZ91 magnesium alloy was carried out by high current pulsed electron beam (HCPEB) with accelerating voltage 27 kV and energy density 3 J/cm2. The surface microstructure and phase composition were characterized by using optical microscope (OM), X-ray diffraction (XRD), and scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS). The surface microhardness and corrosion resistance were measured. Under HCPEB treatments, the preferential evaporation of Mg element occurred intensively on irradiated surface and the initial large Mg17Al12 phases were dissolved. The nano-grained and Al-enriched surface modified layer was ultimately formed of depth ∼8 μm. According to the testing results, the surface microhardness increased from 63 to 141 HK after 30 pulses of HCPEB treatment, while the best improvement of corrosion resistance was obtained by 15 pulses of HCPEB treatment with a cathodic current density decreased by two orders of magnitude as compared with the initial AZ91 sample.

  2. Charge carrier transport in Cu(In,Ga)Se2 thin-film solar-cells studied by electron beam induced current and temperature and illumination dependent current voltage analysis

    International Nuclear Information System (INIS)

    This work contributes to the understanding of generation dependent charge-carrier transport properties in Cu(In,Ga)Se2 (CIGSe)/ CdS/ ZnO solar cells and a consistent model for the electronic band diagram of the heterojunction region of the device is developed. Cross section electron-beam induced current (EBIC) and temperature and illumination dependent current voltage (IV) measurements are performed on CIGSe solar cells with varying absorber layer compositions and CdS thickness. For a better understanding of possibilities and limitations of EBIC measurements applied on CIGSe solar cells, detailed numerical simulations of cross section EBIC profiles for varying electron beam and solar cell parameters are performed and compared to profiles obtained from an analytical description. Especially the effects of high injection conditions are considered. Even though the collection function of the solar cell is not independent of the generation function of the electron beam, the local electron diffusion length in CIGSe can still be extracted. Grain specific values ranging from (480±70) nm to (2.3±0.2) μm are determined for a CuInSe2 absorber layer and a value of (2.8±0.3) μm for CIGSe with a Ga-content of 0.3. There are several models discussed in literature to explain generation dependent charge carrier transport, all assuming a high acceptor density either located in the CIGSe layer close to the CIGSe/CdS interface (p+ layer), within the CdS layer or at the CdS/ZnO interface. In all models, a change in charge carrier collection properties is caused by a generation dependent occupation probability of the acceptor type defect state and the resulting potential distribution throughout the device. Numerical simulations of EBIC and IV data are performed with parameters according to these models. The model that explains the experimental data best is that of a p+ layer at the CIGSe/CdS interface and acceptor type defect states at the CdS/ZnO interface. The p+ layer leads to

  3. Cross-sectional TEM analysis of structural phase states in TiNi alloy treated by a low-energy high-current pulsed electron beam

    International Nuclear Information System (INIS)

    Highlights: • The TiNi melted layer is characterized by changing of chemical composition for the Ti enrichment. • Structure of the B2 phase in the modified zone has considerable distortions of the crystal lattice. • Gradient character of changes of TiNi structure in the modified zone is experimentally shown. - Abstract: The paper reports on a study of structural phase states and their cross-sectional in-depth evolution from the surface of TiNi specimens treated by low-energy high-current electron beams with surface melting at a beam energy density E = 10 J/cm2, number of pulses N = 10, and pulse duration τ = 50 μs. After treatment, the modified TiNi surface zone takes on a layered structure in which each layer differs in phase composition and structural phase state. It is found that the melted layer is 8–10 μm thick. This layer is in a single-B2 phase state with distorted structure, lattice parameters a = b = 3.003–3.033 Å, c = 3.033–3.063 Å and α = 89.3–90°, β = γ = 90°, quasihomogeneous chemical composition corresponding to Ti51.7Ni48.3, the preferred orientations of the crystallites in a direction close to 〈4 1 0〉B2, and inhomogeneous lattice strain. The intermediate layer contains, in addition to the B2 phase, a B19′ martensite phase. The structural state of the B2 phase in this layer is close to equilibrium and its parameters approximate those of the initial B2 phase in nonirradiated TiNi specimens

  4. WELD FORMATION CONTROL AT ELECTRON BEAM WELDING WITH BEAM OSCILLATIONS

    OpenAIRE

    Trushnikov, Dmitriy; Koleva, Elena; Mladenov, Georgy; Shcherbakov, A.

    2014-01-01

    Electron beam welding is used extensively to produce essential machine parts. The control of the basic beam parameters beam power or beam current at constant accelerating voltage, welding speed, current of focusing lens and distance between electron gun and welded sample surface is not enough to obtain at most of the regimes sound welds. Control of the focus position using analysis of the high frequency component of the current, collected by plasma, at periodic interactions on the beam (the o...

  5. The upgraded rf system for the AGS and high intensity proton beams

    Energy Technology Data Exchange (ETDEWEB)

    Brennan, J.M. [Brookhaven National Lab., Upton, NY (United States). AGS Dept.

    1995-05-01

    The AGS has been upgraded over the past three years to produce a record beam intensity of 6 {times} 10{sup 13} protons per pulse for the fixed-target physics program. The major elements of the upgrade are: the new 1.5 GeV Booster synchrotron, the main magnet power supply, a high frequency longitudinal dilution cavity, a feedback damper for transverse instabilities, a fast gamma transition jump system, and a new high-power rf system. The new rf system and its role in achieving the high intensity goal are the subjects of this report. The rf system is heavily beam loaded, with 7 Amps of rf current in the beam and a peak power of 0.75 MW delivered to the beam by ten cavities. As an example of the scale of beam loading, at one point in the acceleration cycle the cavities are operated at 1.5 kV/gap; whereas, were it not for the new power amplifiers, the beam-induced voltage on the cavities would be over 25 kV/gap. The upgraded rf system, comprising: new power amplifiers, wide band rf feedback, improved cavities, and new low-level beam control electronics, is described. Results of measurements with beam, which characterize the system`s performance, are presented. A typical high intensity acceleration cycle is described with emphasis on the key challenges of beam loading.

  6. The upgraded rf system for the AGS and high intensity proton beams

    International Nuclear Information System (INIS)

    The AGS has been upgraded over the past three years to produce a record beam intensity of 6 x 1013 protons per pulse for the fixed-target physics program. The major elements of the upgrade are: the new 1.5 GeV Booster synchrotron, the main magnet power supply, a high frequency longitudinal dilution cavity, a feedback damper for transverse instabilities, a fast gamma transition jump system, and a new high-power rf system. The new rf system and its role in achieving the high intensity goal are the subjects of this report. The rf system is heavily beam loaded, with 7 Amps of rf current in the beam and a peak power of 0.75 MW delivered to the beam by ten cavities. As an example of the scale of beam loading, at one point in the acceleration cycle the cavities are operated at 1.5 kV/gap; whereas, were it not for the new power amplifiers, the beam-induced voltage on the cavities would be over 25 kV/gap. The upgraded rf system, comprising: new power amplifiers, wide band rf feedback, improved cavities, and new low-level beam control electronics, is described. Results of measurements with beam, which characterize the system's performance, are presented. A typical high intensity acceleration cycle is described with emphasis on the key challenges of beam loading

  7. Beam-beam effects

    Energy Technology Data Exchange (ETDEWEB)

    Zholents, A.

    1994-12-01

    The term beam-beam effects is usually used to designate different phenomena associated with interactions of counter-rotating beams in storage rings. Typically, the authors speak about beam-beam effects when such interactions lead to an increase of the beam core size or to a reduction of the beam lifetime or to a growth of particle`s population in the beam halo and a correspondent increase of the background. Although observations of beam-beam effects are very similar in most storage rings, it is very likely that every particular case is largely unique and machine-dependent. This constitutes one of the problems in studying the beam-beam effects, because the experimental results are often obtained without characterizing a machine at the time of the experiment. Such machine parameters as a dynamic aperture, tune dependencies on amplitude of particle oscillations and energy, betatron phase advance between the interaction points and some others are not well known, thus making later analysis uncertain. The authors begin their discussion with demonstrations that beam-beam effects are closely related to non linear resonances. Then, they will show that a non linearity of the space charge field is responsible for the excitation of these resonances. After that, they will consider how beam-beam effects could be intensified by machine imperfections. Then, they will discuss a leading mechanism for the formation of the beam halo and will describe a new technique for beam tails and lifetime simulations. They will finish with a brief discussion of the coherent beam-beam effects.

  8. Core-shell InGaN/GaN nanowire light emitting diodes analyzed by electron beam induced current microscopy and cathodoluminescence mapping

    Science.gov (United States)

    Tchernycheva, M.; Neplokh, V.; Zhang, H.; Lavenus, P.; Rigutti, L.; Bayle, F.; Julien, F. H.; Babichev, A.; Jacopin, G.; Largeau, L.; Ciechonski, R.; Vescovi, G.; Kryliouk, O.

    2015-07-01

    We report on the electron beam induced current (EBIC) microscopy and cathodoluminescence (CL) characterization correlated with compositional analysis of light emitting diodes based on core/shell InGaN/GaN nanowire arrays. The EBIC mapping of cleaved fully operational devices allows to probe the electrical properties of the active region with a nanoscale resolution. In particular, the electrical activity of the p-n junction on the m-planes and on the semi-polar planes of individual nanowires is assessed in top view and cross-sectional geometries. The EBIC maps combined with CL characterization demonstrate the impact of the compositional gradients along the wire axis on the electrical and optical signals: the reduction of the EBIC signal toward the nanowire top is accompanied by an increase of the CL intensity. This effect is interpreted as a consequence of the In and Al gradients in the quantum well and in the electron blocking layer, which influence the carrier extraction efficiency. The interface between the nanowire core and the radially grown layer is shown to produce in some cases a transitory EBIC signal. This observation is explained by the presence of charged traps at this interface, which can be saturated by electron irradiation.We report on the electron beam induced current (EBIC) microscopy and cathodoluminescence (CL) characterization correlated with compositional analysis of light emitting diodes based on core/shell InGaN/GaN nanowire arrays. The EBIC mapping of cleaved fully operational devices allows to probe the electrical properties of the active region with a nanoscale resolution. In particular, the electrical activity of the p-n junction on the m-planes and on the semi-polar planes of individual nanowires is assessed in top view and cross-sectional geometries. The EBIC maps combined with CL characterization demonstrate the impact of the compositional gradients along the wire axis on the electrical and optical signals: the reduction of the EBIC

  9. C++ Coding Standards for the AMP Project

    Energy Technology Data Exchange (ETDEWEB)

    Evans, Thomas M [ORNL; Clarno, Kevin T [ORNL

    2009-09-01

    This document provides an initial starting point to define the C++ coding standards used by the AMP nuclear fuel performance integrated code project and a part of AMP's software development process. This document draws from the experiences, and documentation [1], of the developers of the Marmot Project at Los Alamos National Laboratory. Much of the software in AMP will be written in C++. The power of C++ can be abused easily, resulting in code that is difficult to understand and maintain. This document gives the practices that should be followed on the AMP project for all new code that is written. The intent is not to be onerous but to ensure that the code can be readily understood by the entire code team and serve as a basis for collectively defining a set of coding standards for use in future development efforts. At the end of the AMP development in fiscal year (FY) 2010, all developers will have experience with the benefits, restrictions, and limitations of the standards described and will collectively define a set of standards for future software development. External libraries that AMP uses do not have to meet these requirements, although we encourage external developers to follow these practices. For any code of which AMP takes ownership, the project will decide on any changes on a case-by-case basis. The practices that we are using in the AMP project have been in use in the Denovo project [2] for several years. The practices build on those given in References [3-5]; the practices given in these references should also be followed. Some of the practices given in this document can also be found in [6].

  10. AmpC β-Lactamases

    OpenAIRE

    Jacoby, George A.

    2009-01-01

    Summary: AmpC β-lactamases are clinically important cephalosporinases encoded on the chromosomes of many of the Enterobacteriaceae and a few other organisms, where they mediate resistance to cephalothin, cefazolin, cefoxitin, most penicillins, and β-lactamase inhibitor-β-lactam combinations. In many bacteria, AmpC enzymes are inducible and can be expressed at high levels by mutation. Overexpression confers resistance to broad-spectrum cephalosporins including cefotaxime, ceftazidime, and ceft...

  11. Comparative study of transient current induced in SiC p+n and n+p diodes by heavy ion micro beams

    International Nuclear Information System (INIS)

    N+p and p+n diodes were fabricated on p- and n-type 6H-SiC substrates with epitaxial layers, respectively. The charge induced in the diodes by 9 MeV oxygen (O) and nickel (Ni) ions was measured using Transient Ion Beam Induced Current (TIBIC) to clarify the capability of these diodes as particle detectors. As a result of the TIBIC measurements using 9 MeV O, the Charge Collection Efficiency (CCE) of around 83% was obtained for both p+n and n+p diodes. Since the CCE value includes the consumption of incident ion energy in an Al electrode and the n+ (p+) region as well as the decay of charge in the measurement system, the CCE value obtained in this study indicates that SiC n+p as well as p+n diodes are suitable for particle detectors. On the other hand, in the case of 9 MeV Ni ion irradiation, the CCE for both n+p and p+n diodes decreases due to the Auger recombination in dense electron-hole pairs.

  12. Formation of microcraters and hierarchically-organized surface structures in TiNi shape memory alloy irradiated with a low-energy, high-current electron beam

    International Nuclear Information System (INIS)

    The regularities of surface cratering in TiNi alloy irradiated with a low-energy, high-current electron beam (LEHCEB) in dependence on energy density and number of pulses are studied. LEHCEB processing of TiNi samples was carried out using RITM-SP facility. Energy density Es was varied from 1 to 5 J/cm2, pulse duration was 2.5–3.0 μs, the number of pulses n = 1–128. The dominant role of non-metallic inclusions [mainly, TiC(O)] in the nucleation of microcraters was found. It was revealed that at small number of pulses (n = 2), an increase in energy density leads both to increasing average diameter and density of microcraters. An increase in the number of pulses leads to a monotonic decrease in density of microcraters, and, therefore, that of the proportion of the area occupied by microcraters, as well as a decrease in the surface roughness. The multiple LEHCEB melting of TiNi alloy in crater-free modes enables to form quasi-periodical, hierarchically-organized microsized surface structures

  13. Electron-beam-induced current measurements with applied bias provide insight to locally resolved acceptor concentrations at p-n junctions

    Science.gov (United States)

    Abou-Ras, D.; Schäfer, N.; Baldaz, N.; Brunken, S.; Boit, C.

    2015-07-01

    Electron-beam-induced current (EBIC) measurements have been employed for the investigation of the local electrical properties existing at various types of electrical junctions during the past decades. In the standard configuration, the device under investigation is analyzed under short-circuit conditions. Further insight into the function of the electrical junction can be obtained when applying a bias voltage. The present work gives insight into how EBIC measurements at applied bias can be conducted at the submicrometer level, at the example of CuInSe2 solar cells. From the EBIC profiles acquired across ZnO/CdS/CuInSe2/Mo stacks exhibiting p-n junctions with different net doping densities in the CuInSe2 layers, values for the width of the space-charge region, w, were extracted. For all net doping densities, these values decreased with increasing applied voltage. Assuming a linear relationship between w2 and the applied voltage, the resulting net doping densities agreed well with the ones obtained by means of capacitance-voltage measurements.

  14. Electron-beam-induced current measurements with applied bias provide insight to locally resolved acceptor concentrations at p-n junctions

    International Nuclear Information System (INIS)

    Electron-beam-induced current (EBIC) measurements have been employed for the investigation of the local electrical properties existing at various types of electrical junctions during the past decades. In the standard configuration, the device under investigation is analyzed under short-circuit conditions. Further insight into the function of the electrical junction can be obtained when applying a bias voltage. The present work gives insight into how EBIC measurements at applied bias can be conducted at the submicrometer level, at the example of CuInSe2 solar cells. From the EBIC profiles acquired across ZnO/CdS/CuInSe2/Mo stacks exhibiting p-n junctions with different net doping densities in the CuInSe2 layers, values for the width of the space-charge region, w, were extracted. For all net doping densities, these values decreased with increasing applied voltage. Assuming a linear relationship between w2 and the applied voltage, the resulting net doping densities agreed well with the ones obtained by means of capacitance-voltage measurements

  15. Study on the nanostructure formation mechanism of hypereutectic Al–17.5Si alloy induced by high current pulsed electron beam

    International Nuclear Information System (INIS)

    This work investigates the nanostructure forming mechanism of hypereutectic Al–17.5Si alloy associated with the high current pulsed electron beam (HCPEB) treatment with increasing number of pulses by electron backscatter diffraction (EBSD) and SEM. The surface layers were melted and resolidified rapidly. The treated surfaces show different structural characteristics in different compositions and distribution zones. The top melted-layer zone can be divided into three zones: Si-rich, Ai-rich, and intermediate zone. The Al-rich zone has a nano-cellular microstructure with a diameter of ∼100 nm. The microstructure in the Si-rich zone consists of fine, dispersive, and spherical nano-sized Si crystals surrounded by α(Al) cells. Some superfine eutectic structures form in the boundary of the two zones. With the increase of number of pulses, the proportion of Si-rich zone to the whole top surface increases, and more cellular substructures are transformed to fine equiaxed grain. In other words, with increasing number of pulses, more Si elements diffuse to the Al-rich zone and provide heterogeneous nucleation sites, and Al grains are refined dramatically. Moreover, the relationship between the substrate Si phase and crystalline phase is determined by EBSD; that is, (1 1 1)Al//(0 0 1)Si with a value of disregistry δ at approximately 5%. The HCPEB technique is a versatile technique for refining the surface microstructure of hypereutectic Al–Si alloys

  16. Study on the nanostructure formation mechanism of hypereutectic Al–17.5Si alloy induced by high current pulsed electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Bo, E-mail: gaob@smm.neu.edu.cn [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Hu, Liang [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Li, Shi-wei [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Hao, Yi [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Zhang, Yu-dong [Laboratoire d’Etude des Textures et Applications aux Matériaux (LETAM, UMR-CNRS 7078), Université Paul Verlaine de Metz, Ile du Saulcy, Metz 57012 (France); Tu, Gan-feng [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Grosdidier, Thierry [Laboratoire d’Etude des Textures et Applications aux Matériaux (LETAM, UMR-CNRS 7078), Université Paul Verlaine de Metz, Ile du Saulcy, Metz 57012 (France)

    2015-08-15

    This work investigates the nanostructure forming mechanism of hypereutectic Al–17.5Si alloy associated with the high current pulsed electron beam (HCPEB) treatment with increasing number of pulses by electron backscatter diffraction (EBSD) and SEM. The surface layers were melted and resolidified rapidly. The treated surfaces show different structural characteristics in different compositions and distribution zones. The top melted-layer zone can be divided into three zones: Si-rich, Ai-rich, and intermediate zone. The Al-rich zone has a nano-cellular microstructure with a diameter of ∼100 nm. The microstructure in the Si-rich zone consists of fine, dispersive, and spherical nano-sized Si crystals surrounded by α(Al) cells. Some superfine eutectic structures form in the boundary of the two zones. With the increase of number of pulses, the proportion of Si-rich zone to the whole top surface increases, and more cellular substructures are transformed to fine equiaxed grain. In other words, with increasing number of pulses, more Si elements diffuse to the Al-rich zone and provide heterogeneous nucleation sites, and Al grains are refined dramatically. Moreover, the relationship between the substrate Si phase and crystalline phase is determined by EBSD; that is, (1 1 1){sub Al}//(0 0 1){sub Si} with a value of disregistry δ at approximately 5%. The HCPEB technique is a versatile technique for refining the surface microstructure of hypereutectic Al–Si alloys.

  17. Study on the nanostructure formation mechanism of hypereutectic Al-17.5Si alloy induced by high current pulsed electron beam

    Science.gov (United States)

    Gao, Bo; Hu, Liang; Li, Shi-wei; Hao, Yi; Zhang, Yu-dong; Tu, Gan-feng; Grosdidier, Thierry

    2015-08-01

    This work investigates the nanostructure forming mechanism of hypereutectic Al-17.5Si alloy associated with the high current pulsed electron beam (HCPEB) treatment with increasing number of pulses by electron backscatter diffraction (EBSD) and SEM. The surface layers were melted and resolidified rapidly. The treated surfaces show different structural characteristics in different compositions and distribution zones. The top melted-layer zone can be divided into three zones: Si-rich, Ai-rich, and intermediate zone. The Al-rich zone has a nano-cellular microstructure with a diameter of ∼100 nm. The microstructure in the Si-rich zone consists of fine, dispersive, and spherical nano-sized Si crystals surrounded by α(Al) cells. Some superfine eutectic structures form in the boundary of the two zones. With the increase of number of pulses, the proportion of Si-rich zone to the whole top surface increases, and more cellular substructures are transformed to fine equiaxed grain. In other words, with increasing number of pulses, more Si elements diffuse to the Al-rich zone and provide heterogeneous nucleation sites, and Al grains are refined dramatically. Moreover, the relationship between the substrate Si phase and crystalline phase is determined by EBSD; that is, (1 1 1)Al//(0 0 1)Si with a value of disregistry δ at approximately 5%. The HCPEB technique is a versatile technique for refining the surface microstructure of hypereutectic Al-Si alloys.

  18. Klystron beam bunching

    International Nuclear Information System (INIS)

    A detailed description of electron-beam bunching phenomena in klystrons is presented. Beam harmonic current is defined, both space-charge and ballistic bunching are analyzed, Ramo's theorem is used to describe how a bunched beam drives a cavity, and a general cavity model including external coupling is provided. (author)

  19. Current breaking in the injector of the ion induction accelerator

    International Nuclear Information System (INIS)

    Production of kilo amp ion beams in gas-filled diode with magnetic insulation under the current breaking at 200-400 kV of accelerating voltages and ∼ 30 kA of diode total currents, the pulse duration being ∼ 10-6 s, is experimentally studied. The current breaking in the diode takes place when the working gas concentration in A-K gap is h0 ∼ 2x1014 cm-3 (hydrogen). This results in a 6-fold peaking of the diode power with a 2-fold accelerating voltage increase. Therewith the ion current duration is reduced 3 times and constitutes ∼ 100-200 ns. 3 refs.; 3 figs

  20. Intense positron beams: linacs

    International Nuclear Information System (INIS)

    Beams of monoenergetic positrons with energies of a few eV to many keV have been used in experiments in atomic physics, solid-state physics and materials science. The production of positron beams from a new source, an electron linac, is described. Intense, pulsed beams of low-energy positrons were produced by a high-energy beam from an electron linac. The production efficiency, moderator geometry, beam spot size and other positron beam parameters were determined for electrons with energies from 60 to 120 MeV. Low-energy positron beams produced with a high-energy electron linac can be of much higher intensity than those beams currently derived from radioactive sources. These higher intensity beams will make possible positron experiments previously infeasible. 10 references, 1 figure