Science.gov

Sample records for beam loss control

  1. Fermilab main injector: High intensity operation and beam loss control

    NASA Astrophysics Data System (ADS)

    Brown, Bruce C.; Adamson, Philip; Capista, David; Chou, Weiren; Kourbanis, Ioanis; Morris, Denton K.; Seiya, Kiyomi; Wu, Guan Hong; Yang, Ming-Jen

    2013-07-01

    From 2005 through 2012, the Fermilab Main Injector provided intense beams of 120 GeV protons to produce neutrino beams and antiprotons. Hardware improvements in conjunction with improved diagnostics allowed the system to reach sustained operation at 400 kW beam power. Transmission was very high except for beam lost at or near the 8 GeV injection energy where 95% beam transmission results in about 1.5 kW of beam loss. By minimizing and localizing loss, residual radiation levels fell while beam power was doubled. Lost beam was directed to either the collimation system or to the beam abort. Critical apertures were increased while improved instrumentation allowed optimal use of available apertures. We will summarize the improvements required to achieve high intensity, the impact of various loss control tools and the status and trends in residual radiation in the Main Injector.

  2. Beam Loss Control for the NSLS-II Storage Ring

    SciTech Connect

    Kramer, S.L.; Choi, J.

    2011-03-28

    The shielding design for the NSLS-II storage ring is designed for the full injected beam losses in two periods of the ring around the injection point, but for the remainder of the ring its shielded for {le} 10% top-off injection beam. This will require a system to insure that beam losses do not exceed these levels for time sufficient to cause excessive radiation exposure outside the shield walls. This beam Loss Control and Monitoring (LCM) system will control the beam losses to the more heavily shielded injection region while monitoring the losses outside this region. To achieve this scrapers are installed in the injection region to intercept beam particles that might be lost outside this region. The scrapers will be thin (< 1Xrad) that will allow low energy electrons to penetrate and the subsequent dipole will separate them from the stored beam. These thin scrapers will reduce the radiation from the scraper compared to thicker scrapers. The dipole will provide significant local shielding for particles that hit inside the gap and a source for the loss monitor system that will measure the amount of beam lost in the injection region.

  3. Characterizing and Controlling Beam Losses at the LANSCE Facility

    SciTech Connect

    Rybarcyk, Lawrence J.

    2012-09-12

    The Los Alamos Neutron Science Center (LANSCE) currently provides 100-MeV H{sup +} and 800-MeV H{sup -} beams to several user facilities that have distinct beam requirements, e.g. intensity, micropulse pattern, duty factor, etc. Minimizing beam loss is critical to achieving good performance and reliable operation, but can be challenging in the context of simultaneous multi-beam delivery. This presentation will discuss various aspects related to the observation, characterization and minimization of beam loss associated with normal production beam operations in the linac.

  4. BEAM LOSS ESTIMATES AND CONTROL FOR THE BNL NEUTRINO FACILITY.

    SciTech Connect

    WENG, W.-T.; LEE, Y.Y.; RAPARIA, D.; TSOUPAS, N.; BEEBE-WANG, J.; WEI, J.; ZHANG, S.Y.

    2005-05-16

    The requirement for low beam loss is very important both to protect the beam component, and to make the hands-on maintenance possible. In this report, the design considerations to achieving high intensity and low loss will be presented. We start by specifying the beam loss limit at every physical process followed by the proper design and parameters for realizing the required goals. The process considered in this paper include the emittance growth in the linac, the H{sup -} injection, the transition crossing, the coherent instabilities and the extraction losses.

  5. Issues and experience with controlling beam loss at the Tevatron collider

    SciTech Connect

    Annala, Gerald; /Fermilab

    2007-07-01

    Controlling beam loss in the Tevatron collider is of great importance because of the delicate nature of the cryogenic magnet system and the collider detectors. Maximizing the physics potential requires optimized performance as well as protection of all equipment. The operating history of the Tevatron has significantly influenced the way losses are managed. The development of beam loss management in the Tevatron will be presented.

  6. Micro-nanopores fabricated by high-energy electron beam irradiation: suitable structure for controlling pesticide loss.

    PubMed

    Xiang, Yubin; Wang, Ning; Song, Jimei; Cai, Dongqing; Wu, Zhengyan

    2013-06-05

    Pesticide sprayed onto crop leaves tends to be washed off by rainwater and discharge into the environment through leaching and runoff, resulting in severe pollution to both soil and water. Here, to control pesticide loss, we developed a loss-control pesticide (LCP) by adding modified natural nanoclay (diatomite) through high-energy electron beam (HEEB) to traditional pesticide. After HEEB treatment, the originally clogged pores in diatomite opened, resulting in plenty of micro-nanopores in diatomite, which are beneficial for the pesticide molecules to access and be adsorbed. This pesticide-diatomite complex tended to be retained by the rough surface of crop leaves, displaying a high adhesion performance onto the leaves, so that the pesticide loss reduced, sufficient pesticide for crops was supplied, and the pollution risk of the pesticide could be substantially lowered.

  7. RHIC BEAM LOSS MONITOR SYSTEM INITIAL OPERATION.

    SciTech Connect

    WITKOVER,R.L.; MICHNOFF,R.J.; GELLER,J.M.

    1999-03-29

    The RHIC Beam Loss Monitor (BLM) System is designed to prevent beam loss quenching of the superconducting magnets, and acquire loss data. Four hundred ion chambers are located around the rings to detect losses. The required 8-decade range in signal current is compressed using an RC pre- integrator ahead of a low current amplifier. A beam abort may be triggered if fast or slow losses exceed programmable threshold levels. A micro-controller based VME module sets references and gains and reads trip status for up to 64 channels. Results obtained with the detectors in the RHIC Sextant Test and the prototype electronics in the AGS-to-RHIC (AtR) transfer line are presented along with the present status of the system.

  8. Refining Tungsten Purification by Electron Beam Melting Based on the Thermal Equilibrium Calculation and Tungsten Loss Control

    NASA Astrophysics Data System (ADS)

    Long, Luping; Liu, Wensheng; Ma, Yunzhu; Liu, Ye; Liu, Shuhua

    2015-10-01

    Electron beam melting (EBM) technology has been considered as one of the key steps for preparing high purity tungsten, and reasonable setting of process parameters is the premise. In this paper, the optimum process parameters obtained from thermal equilibrium calculation and evaporation loss control of tungsten are presented. Effective power is closely related to melting temperature, and the required power for maintaining the superheating melt linearly increases with the increase of melt superheat temperature. The evaporation loss behavior of tungsten is significantly influenced by melting rate and melting temperature. Analysis of experiments show that the best results are realized at melting rate of 1.82 g/s, melting temperature of 4200 K, and the corresponding melting power of 130 kW, in which the main impurity elements in tungsten, such as As, Cd, Mg and Sn, present high removal ratio of 90%, 95%, 85.7% and 90%, respectively.

  9. RHIC beam loss monitor system design

    SciTech Connect

    Witkover, R.; Zitvogel, E.; Michnoff, R.

    1997-07-01

    The Beam Loss Monitor (BLM) System is designed to prevent the quenching of RHIC magnets due to beam loss, provide quantitative loss data, and the loss history in the event of a beam abort. The system uses 400 ion chambers of a modified Tevatron design. To satisfy fast (single turn) and slow (100 msec) loss beam criteria and provide sensitivity for studies measurements, a range of over 8 decades is needed. An RC pre-integrator reduces the dynamic range for a low current amplifier. This is digitized for data logging. The output is also applied to an analog multiplier which compensates the energy dependence, extending the range of the abort comparators. High and low pass filters separate the signal to dual comparators with independent programmable trip levels. Up to 64 channels, on 8 VME boards, are controlled by a micro-controller based VME module, decoupling it from the front-end computer (FEC) for real-time operation. Results with the detectors in the RHIC Sextant Test and the electronics in the AGS-to-RHIC (AtR) transfer line will be presented.

  10. Preliminary comments about beam loss

    SciTech Connect

    Groom, D.

    1985-10-01

    A variety of beam loss questions are being investigated. They affect several design issues, ranging from machine-associated background in the detectors to the radiation lifetime of the main-ring magnets: (1) Muons. Oppositely directed muon beams from prompt muon production, primary meson decay, and a variety of other processes radiate from each IR. If they were not fanned by the insertion dipoles, the beams would be sufficiently intense and energetic that they would present a radiation hazard even after penetrating 2 km of soil or rock. (2) Machine-associated background in the IR`s. About 30 mb of the total cross section is elastic or quasi-elastic, and most of the protons are in a Gaussian spot with sigma = 9 mr. These particles are well within the machine acceptance, but there is a grey area in the tail of the distributions in which the scattered particles `almost` remain in orbit - they continue for some distance but eventually hit a wall. (3) Cryogenic load. This problem has been addressed to some degree in the RDS, but considerably more detail is needed. It appears that a very large fraction of the inelastic particle energy will be deposited here. (4) Radiation damage in the ring. The lifetime of both magnets and electronics in the tunnel might be limited by radiation due to particle loss. Early results are not reassuring. Tevatron measurements, reported to the authors by John Elias, indicate that most of the tunnel background comes from particle loss due to beam-gas collisions.

  11. RHIC low energy beam loss projections

    SciTech Connect

    Satogata,T.

    2009-08-01

    For RHIC low-energy operations, we plan to collide Au beams with energies of E = 2:5-10 GeV/u in RHIC. Beams are injected into collision optics, and RHIC runs as a storage ring with no acceleration. At these low energies, observed beam lifetimes are minutes, with measured beam lifetimes of 3.5 min (fast) and 50 min (slow) at E=4.6 GeV/u in the March 2008 test run. With these lifetimes we can operate RHIC as a storage ring to produce reasonable integrated luminosity. This note estimates beam losses and collimator/dump energy deposition in normal injection modes of low energy operation. The main question is whether a normal injection run is feasible for an FY10 10-15 week operations run from a radiation safety perspective. A peripheral question is whether continuous injection operations is feasible from a radiation safety perspective. In continuous injection mode, we fill both rings, then continuously extract and reinject the oldest bunches that have suffered the most beam loss to increase the overall integrated luminosity. We expect to gain a factor of 2-3 in integrated luminosity from continuous injection at lowest energies if implemented[1]. Continuous injection is feasible by FY11 from an engineering perspective given enough effort, but the required extra safety controls and hardware dose risk make it unappealing for the projected luminosity improvement. Low-energy electron cooling will reduce beam losses by at least an order of magnitude vs normal low-energy operations, but low energy cooling is only feasible in the FY13 timescale and therefore beyond the scope of this note. For normal injection low energy estimates we assume the following: (1) RHIC beam total energies are E=2.5-10 GeV/u. (Continuous injection mode is probably unnecessary above total energies of E=7-8 GeV/u.); (2) RHIC operates only as a storage ring, with no acceleration; (3) 110 bunches of about 0.5-1.0 x 10{sup 9} initial bunch intensities (50-100% injection efficiency, likely conservative

  12. Analysis of beam loss mechanism in the Project X linac

    SciTech Connect

    Carneiro, J.-P.; Lebedev, V.; Nagaitsev, S.; Ostiguy, J.-F.; Solyak, N.; /Fermilab

    2011-03-01

    Minimization of the beam losses in a multi-MW H{sup -} linac such as ProjectX to a level below 1 W/m is a challenging task. The impact of different mechanism of beam stripping, including stripping in electric and magnetic fields, residual gas, blackbody radiation and intra-beam stripping, is analyzed. Other sources of beam losses are misalignements of beamline elements and errors in RF fields and phases. We present in this paper requirements for dynamic errors and correction schemes to keep beam losses under control.

  13. BEAM LOSS MECHANISMS IN HIGH INTENSITY LINACS

    SciTech Connect

    Plum, Michael A

    2012-01-01

    In the present operation of the Oak Ridge Spallation Neutron Source, 60-Hz, 825-us H beam pulses are accelerated to 910 MeV, and then compressed to less than a microsecond in the storage ring, to deliver 1 MW of beam power to the spallation target. The beam loss in the superconducting portion of the linac is higher than expected, and it has shown a surprising counter-intuitive correlation with quadrupole magnetic fields, with a loss minimum occurring when the quadrupoles are set to approximately half their design values. This behavior can now be explained by a recent set of experiments that show the beam loss is primarily due to intra-beam stripping. Beam halo is another important beam loss contributor, and collimation in the 2.5 MeV Medium Energy Beam Transport has proven to be an effective mitigation strategy. In this presentation, we will summarize these and other beam loss mechanisms that are important for high intensity linacs.

  14. Beam Loss Monitors for NSLS-II Storage Ring

    SciTech Connect

    Kramer, S.L.; Cameron, P.

    2011-03-28

    The shielding for the NSLS-II storage ring will provide adequate protection for the full injected beam losses in two cells of the ring around the injection point, but the remainder of the ring is shielded for lower losses of <10% top-off injection beam current. This will require a system to insure that beam losses do not exceed levels for a period of time that could cause excessive radiation exposure outside the shield walls. This beam Loss Control and Monitoring system will have beam loss monitors that will measure where the beam charge is lost around the ring, to warn operators if losses approach the design limits. To measure the charge loss quantitatively, we propose measuring the electron component of the shower as beam electrons hit the vacuum chamber (VC) wall. This will be done using the Cerenkov light as electrons transit ultra-pure fused silica rods placed close to the inner edge of the VC. The entire length of the rod will collect light from the electrons of the spread out shower resulting from the small glancing angle of the lost beam particles to the VC wall. The design and measurements results of the prototype Cerenkov BLM will be presented.

  15. Beam Loss Monitoring for LHC Machine Protection

    NASA Astrophysics Data System (ADS)

    Holzer, Eva Barbara; Dehning, Bernd; Effnger, Ewald; Emery, Jonathan; Grishin, Viatcheslav; Hajdu, Csaba; Jackson, Stephen; Kurfuerst, Christoph; Marsili, Aurelien; Misiowiec, Marek; Nagel, Markus; Busto, Eduardo Nebot Del; Nordt, Annika; Roderick, Chris; Sapinski, Mariusz; Zamantzas, Christos

    The energy stored in the nominal LHC beams is two times 362 MJ, 100 times the energy of the Tevatron. As little as 1 mJ/cm3 deposited energy quenches a magnet at 7 TeV and 1 J/cm3 causes magnet damage. The beam dumps are the only places to safely dispose of this beam. One of the key systems for machine protection is the beam loss monitoring (BLM) system. About 3600 ionization chambers are installed at likely or critical loss locations around the LHC ring. The losses are integrated in 12 time intervals ranging from 40 μs to 84 s and compared to threshold values defined in 32 energy ranges. A beam abort is requested when potentially dangerous losses are detected or when any of the numerous internal system validation tests fails. In addition, loss data are used for machine set-up and operational verifications. The collimation system for example uses the loss data for set-up and regular performance verification. Commissioning and operational experience of the BLM are presented: The machine protection functionality of the BLM system has been fully reliable; the LHC availability has not been compromised by false beam aborts.

  16. Numerical investigation on the generation of high-order Laguerre-Gaussian beams in end-pumped solid-state lasers by introducing loss control.

    PubMed

    Hu, Ajian; Lei, Jian; Chen, Peifeng; Wang, Ying; Li, Shumo

    2014-11-20

    This paper reports a robust and systematic approach to generate high-order scalar Laguerre-Gaussian (LGp,l) beams in end-pumped solid-state lasers by introducing loss control. Based on the spatial distributions of Laguerre-Gaussian modes and the theory of transverse mode selection, the "loss control" is implemented by an amplitude mask in the resonator. This proposed mechanism can be divided into three categories: radial loss, azimuthal loss, and the combination of radial and azimuthal loss, which correspond to excite radial high-order modes (LGp,0), azimuthal high-order modes (LG0,l), and regular high-order modes (LGp,l), respectively. By controlling the locations and thicknesses of opaque rings and lines on the mask, all kinds of LGp,l modes can be obtained. With the application of mode purity, all the generated modes possess high mode purities greater than 93% in simulation.

  17. The ATLAS Beam Condition and Beam Loss Monitors

    NASA Astrophysics Data System (ADS)

    Dolenc, I.

    2010-04-01

    The primary goal of ATLAS Beam Condition Monitor (BCM) and Beam Loss Monitor (BLM) is to protect the ATLAS Inner Detector against damaging LHC beam incidents by initiating beam abort in case of beam failures. Poly-crystalline Chemical Vapour Deposition (pCVD) diamond was chosen as the sensor material for both systems. ATLAS BCM will provide real-time monitoring of instantaneous particle rates close to the interaction point (IP) of ATLAS spectrometer. Using fast front-end and signal processing electronics the time-of-flight and pulse amplitude measurements will be performed to distinguish between normal collisions and background events due to natural or accidental beam losses. Additionally, BCM will also provide coarse relative luminosity information. A second system, the ATLAS BLM, is an independent system which was recently added to complement the BCM. It is a current measuring system and was partially adopted from the BLM system developed by the LHC beam instrumentation group with pCVD diamond pad sensors replacing the ionisation chambers. The design of both systems and results of operation in ATLAS framework during the commissioning with cosmic rays will be reported in this contribution.

  18. Neutral Beam Ion Loss Modeling for NSTX

    SciTech Connect

    D. Mikkelsen; D.S. Darrow; L. Grisham; R. Akers; S. Kaye

    1999-06-01

    A numerical model, EIGOL, has been developed to calculate the loss rate of neutral beam ions from NSTX and the resultant power density on the plasma facing components. This model follows the full gyro-orbit of the beam ions, which can be a significant fraction of the minor radius. It also includes the three-dimensional structure of the plasma facing components inside NSTX. Beam ion losses from two plasma conditions have been compared: {beta} = 23%, q{sub 0} = 0.8, and {beta} = 40%, q{sub 0} = 2.6. Global losses are computed to be 4% and 19%, respectively, and the power density on the rf antenna is near the maximum tolerable levels in the latter case.

  19. Electron beam control for barely separated beams

    DOEpatents

    Douglas, David R.; Ament, Lucas J. P.

    2017-04-18

    A method for achieving independent control of multiple beams in close proximity to one another, such as in a multi-pass accelerator where coaxial beams are at different energies, but moving on a common axis, and need to be split into spatially separated beams for efficient recirculation transport. The method for independent control includes placing a magnet arrangement in the path of the barely separated beams with the magnet arrangement including at least two multipole magnets spaced closely together and having a multipole distribution including at least one odd multipole and one even multipole. The magnetic fields are then tuned to cancel out for a first of the barely separated beams to allow independent control of the second beam with common magnets. The magnetic fields may be tuned to cancel out either the dipole component or tuned to cancel out the quadrupole component in order to independently control the separate beams.

  20. Beam Techniques - Beam Control and Manipulation

    SciTech Connect

    Minty, Michiko G

    2003-04-24

    We describe commonly used strategies for the control of charged particle beams and the manipulation of their properties. Emphasis is placed on relativistic beams in linear accelerators and storage rings. After a brief review of linear optics, we discuss basic and advanced beam control techniques, such as transverse and longitudinal lattice diagnostics, matching, orbit correction and steering, beam-based alignment, and linac emittance preservation. A variety of methods for the manipulation of particle beam properties are also presented, for instance, bunch length and energy compression, bunch rotation, changes to the damping partition number, and beam collimation. The different procedures are illustrated by examples from various accelerators. Special topics include injection and extraction methods, beam cooling, spin transport and polarization.

  1. ABL beam control segment

    NASA Astrophysics Data System (ADS)

    Kelchner, Bryan L.; Dauk, Ronald C.

    1998-09-01

    The U.S. Air Force Airborne Laser consists of four primary subsystem segments; aircraft, battle management and C4I, laser device, and beam control segment (BCS). The BCS performs two major function, beam control and fire control, using three primary products, turret assembly, beam transfer assembly, and fire control hardware and software. The fire control sequence involves slewing the turret to the target coordinates as received from the battle management segment, centering the target in the acquisition sensor, acquiring the plume in the coarse track sensor, acquiring the hard body of the missile with the track illuminator laser, and establishing active tracking of the nose of the target theater ballistic missile. The beam control sequence begins after established active nose track by firing another beacon illuminator laser (BILL) to establish the aim point on the missile for the high energy laser. The resulting spot on the missile is imaged in the wavefront sensor and compared with the outgoing sample of the BILL. By applying the conjugate of the wavefront difference from the beacon to a deformable mirror then the atmosphere serves to correct the arriving wavefront on target. At this point the HEL is fired along the same path with similar wavefront correction, and dwells on target until the missile skin is weakened and rips open or buckles.

  2. RHIC Beam Loss Monitor System Design and Test

    NASA Astrophysics Data System (ADS)

    Witkover, R.; Zitvogel, E.; Michnoff, R.

    1997-05-01

    The Beam Loss Monitor System is designed to prevent the quenching of RHIC magnets due to beam loss, provide quantitative loss data, and the loss history in the event of a beam abort. To satisfy fast (single turn) and slow (100 msec) loss beam abort criteria and provide sensitivity for studies measurements, a range of over 8 decades is needed. The system uses 400 ion chambers of a modified Tevatron design. An RC pre-integrator reduces the dynamic range for a low current amplifier. This is digitized by a standard RHIC VME MADC preceded by a switchable gain amplifier. The output also goes to an analog multiplier used to reduce energy dependence, extending the range of the abort comparators. Fast and slow filters separate the signal to dual comparators with independent trip levels. The gains, fast and slow abort levels, and abort bit masks are set for each channel on receipt of specific RHIC Event Codes. Up to 64 channels, on 8 VME boards, are controlled by a BNL designed micro-controller based VME module, decoupling it from the front-end computer for real-time operation.

  3. Optical beam jitter control

    NASA Astrophysics Data System (ADS)

    Watkins, R. Joseph; Chen, Hong-Jen; Agrawal, Brij N.; Shin, Young S.

    2004-06-01

    For several future imaging and communications spacecraft, a challenging area of technology development is the fine acquisition, tracking, and pointing (ATP) control of the spacecraft and its payload. For example, some spacecraft with large aperture(s) in the range of 10~30 m diameter requires a few arc-seconds accuracy, 10~15 nano-radians jitter, and a fast slewing rate to acquire the target. Furthermore these stringent requirements are at risk of great structure and control interactions. This paper we will focus on the control of optical beam jitter. A Laser Jitter Control (LJC) testbed has been constructed to test jitter algorithms. The testbed consists of two fast steering mirrors (FSM), three position sensing modules (PSM), one diode laser, and several beam splitters and mirrors, all on an isolated Newport optical bench. Jitter is injected with one FSM and the other FSM is used to control it. The jitter spectrum, representing the on-orbit spacecraft and beam jitter environment, contains not only narrow band noise due to rotating devices such as gyroscopes and reaction wheels but also broadband noise. The performance of a Wiener Filter-adaptive algorithm with ideal reference signal is established as the baseline for comparison of adaptive control methods in suppressing both broadband and narrowband disturbances. Specifically, the Least Mean Squares (LMS) approach and the Gradient Adaptive Lattice (GAL) approach are investigated during these experiments.

  4. Luminosity Loss due to Beam Distortion and the Beam-Beam Instability

    SciTech Connect

    Wu, Juhao; Raubenheimer, T.O.; Chao, A.W.; Seryi, A.; Sramek, C.K.; /Rice U.

    2005-06-30

    In a linear collider, sources of emittance dilution such as transverse wakefields or dispersive errors will couple the vertical phase space to the longitudinal position within the beam (the so-called ''banana effect''). When the Intersection Point (IP) disruption parameter is large, these beam distortions will be amplified by a single bunch kink instability which will lead to luminosity loss. We study this phenomena both analytically using linear theory and via numerical simulation. In particular, we examine the dependence of the luminosity loss on the wavelength of the beam distortions and the disruption parameter. This analysis may prove useful when optimizing the vertical disruption parameter for luminosity operation with given beam distortions.

  5. Neutral particle beam intensity controller

    DOEpatents

    Dagenhart, W.K.

    1984-05-29

    The neutral beam intensity controller is based on selected magnetic defocusing of the ion beam prior to neutralization. The defocused portion of the beam is dumped onto a beam dump disposed perpendicular to the beam axis. Selective defocusing is accomplished by means of a magnetic field generator disposed about the neutralizer so that the field is transverse to the beam axis. The magnetic field intensity is varied to provide the selected partial beam defocusing of the ions prior to neutralization. The desired focused neutral beam portion passes along the beam path through a defining aperture in the beam dump, thereby controlling the desired fraction of neutral particles transmitted to a utilization device without altering the kinetic energy level of the desired neutral particle fraction. By proper selection of the magnetic field intensity, virtually zero through 100% intensity control of the neutral beam is achieved.

  6. Fluid-loss control

    SciTech Connect

    Crowe, C.W.; Trittipo, B.L. ); Hutchinson, B.H. )

    1989-08-01

    Acid fluid loss is extremely difficult to control and is generally considered to be the major factor limiting the effectiveness of acid fracturing treatments. Chemical erosion of fracture faces and the development of wormholes are largely responsible for the reduced efficiency of acid fracturing fluids. The creation of acid wormholes increases the effective area from which leakoff occurs, thus reducing the acid hydraulic efficiency. Once wormholes form, most acid fluid loss originates from these wormholes rather than penetrating uniformly into the fracture face. Methods of acid fluid-loss control are discussed and evaluated with an improved fluid-loss test procedure. This procedure uses limestone cores of sufficient length to contain wormhole growth. Studies demonstrate that if wormhole growth can be controlled, acid fluid loss approaches that of nonreactive fluids. An improved acid fracturing fluid having unique rheological characteristics is described. This acid has a low initial viscosity but temporarily becomes extremely viscous during leakoff. This high leakoff viscosity blocks wormhole development and prevents acid entry into natural fractures. After the treatment, spent-acid viscosity declines rapidly to ensure easier cleanup.

  7. Analysis of beam loss induced abort kicker instability

    SciTech Connect

    Zhang W.; Sandberg, J.; Ahrens, L.; Fischer, W.; Hahn, H.; Mi, J.; Pai, C.; Tan, Y.

    2012-05-20

    Through more than a decade of operation, we have noticed the phenomena of beam loss induced kicker instability in the RHIC beam abort systems. In this study, we analyze the short term beam loss before abort kicker pre-fire events and operation conditions before capacitor failures. Beam loss has caused capacitor failures and elevated radiation level concentrated at failed end of capacitor has been observed. We are interested in beam loss induced radiation and heat dissipation in large oil filled capacitors and beam triggered thyratron conduction. We hope the analysis result would lead to better protection of the abort systems and improved stability of the RHIC operation.

  8. Calculation of prompt loss and toroidal field ripple loss under neutral beam injection on EAST

    NASA Astrophysics Data System (ADS)

    Wu, Bin; Hao, Baolong; White, Roscoe; Wang, Jinfang; Zang, Qing; Han, Xiaofeng; Hu, Chundong

    2017-02-01

    Neutral beam injection is a major auxiliary heating method in the EAST experimental campaign. This paper gives detailed calculations of beam loss with different plasma equilibria using the guiding center code ORBIT and NUBEAM/TRANSP. Increasing plasma current can dramatically lower the beam ion prompt loss and ripple loss. Countercurrent beam injection gives a much larger prompt loss fraction than co-injection, and ripple-induced collisionless stochastic diffusion is the dominant loss channel.

  9. Calculation of prompt loss and toroidal field ripple loss under neutral beam injection on EAST

    DOE PAGES

    Wu, Bin; Hao, Baolong; White, Roscoe; ...

    2016-12-09

    Here, neutral beam injection is a major auxiliary heating method in the EAST experimental campaign. This paper gives detailed calculations of beam loss with different plasma equilibria using the guiding center code ORBIT and NUBEAM/TRANSP. Increasing plasma current can dramatically lower the beam ion prompt loss and ripple loss. Countercurrent beam injection gives a much larger prompt loss fraction than co-injection, and ripple-induced collisionless stochastic diffusion is the dominant loss channel.

  10. Calculation of prompt loss and toroidal field ripple loss under neutral beam injection on EAST

    SciTech Connect

    Wu, Bin; Hao, Baolong; White, Roscoe; Wang, Jinfang; Zang, Qing; Han, Xiaofeng; Hu, Chundong

    2016-12-09

    Here, neutral beam injection is a major auxiliary heating method in the EAST experimental campaign. This paper gives detailed calculations of beam loss with different plasma equilibria using the guiding center code ORBIT and NUBEAM/TRANSP. Increasing plasma current can dramatically lower the beam ion prompt loss and ripple loss. Countercurrent beam injection gives a much larger prompt loss fraction than co-injection, and ripple-induced collisionless stochastic diffusion is the dominant loss channel.

  11. BEAM LOSS MITIGATION IN THE OAK RIDGE SPALLATION NEUTRON SOURCE

    SciTech Connect

    Plum, Michael A

    2012-01-01

    The Oak Ridge Spallation Neutron Source (SNS) accelerator complex routinely delivers 1 MW of beam power to the spallation target. Due to this high beam power, understanding and minimizing the beam loss is an ongoing focus area of the accelerator physics program. In some areas of the accelerator facility the equipment parameters corresponding to the minimum loss are very different from the design parameters. In this presentation we will summarize the SNS beam loss measurements, the methods used to minimize the beam loss, and compare the design vs. the loss-minimized equipment parameters.

  12. Neutral particle beam intensity controller

    DOEpatents

    Dagenhart, William K.

    1986-01-01

    A neutral beam intensity controller is provided for a neutral beam generator in which a neutral beam is established by accelerating ions from an ion source into a gas neutralizer. An amplitude modulated, rotating magnetic field is applied to the accelerated ion beam in the gas neutralizer to defocus the resultant neutral beam in a controlled manner to achieve intensity control of the neutral beam along the beam axis at constant beam energy. The rotating magnetic field alters the orbits of ions in the gas neutralizer before they are neutralized, thereby controlling the fraction of neutral particles transmitted out of the neutralizer along the central beam axis to a fusion device or the like. The altered path or defocused neutral particles are sprayed onto an actively cooled beam dump disposed perpendicular to the neutral beam axis and having a central open for passage of the focused beam at the central axis of the beamline. Virtually zero therough 100% intensity control is achieved by varying the magnetic field strength without altering the ion source beam intensity or its species yield.

  13. Beam loss ion chamber system upgrade for experimental halls

    SciTech Connect

    D. Dotson; D. Seidman

    2005-08-01

    The Beam loss Ion Chamber System (BLICS) was developed to protect Jefferson Labs transport lines, targets and beam dumps from a catastrophic ''burn through''. Range changes and testing was accomplished manually requiring the experiment to be shut down. The new upgraded system is based around an ''off the shelf'' Programmable Logic Controller located in a single control box supporting up to ten individual detectors. All functions that formerly required an entry into the experimental hall and manual adjustment can be accomplished from the Machine Control Center (MCC). A further innovation was the addition of a High Voltage ''Brick'' at the detector location. A single cable supplies the required voltage for the Brick and a return line for the ion chamber signal. The read back screens display range, trip point, and accumulated dose for each location. The new system is very cost effective and significantly reduces the amount of lost experimental time.

  14. Beam Loss Ion Chamber System Upgrade for Experimental Halls

    SciTech Connect

    D.W. Dotson; D.J. Seidman

    2005-05-16

    The Beam loss Ion Chamber System (BLICS) was developed to protect Jefferson Labs transport lines, targets and beam dumps from a catastrophic ''burn through''. Range changes and testing was accomplished manually requiring the experiment to be shut down. The new upgraded system is based around an ''off the shelf'' Programmable Logic Controller located in a single control box supporting up to ten individual detectors. All functions that formerly required an entry into the experimental hall and manual adjustment can be accomplished from the Machine Control Center (MCC). A further innovation was the addition of a High Voltage ''Brick'' at the detector location. A single cable supplies the required voltage for the Brick and a return line for the ion chamber signal. The read back screens display range, trip point, and accumulated dose for each location. The new system is very cost effective and significantly reduces the amount of lost experimental time.

  15. BEAM CONTROL PROBE

    DOEpatents

    Chesterman, A.W.

    1959-03-17

    A probe is described for intercepting a desired portion of a beam of charged particles and for indicating the spatial disposition of the beam. The disclosed probe assembly includes a pair of pivotally mounted vanes moveable into a single plane with adjacent edges joining and a calibrated mechanical arrangement for pivoting the vancs apart. When the probe is disposed in the path of a charged particle beam, the vanes may be adjusted according to the beam current received in each vane to ascertain the dimension of the beam.

  16. Beam Loss Studies for the 2-MW LBNE Proton Beam Line

    SciTech Connect

    Drozhdin, A.I.; Childress, S.R.; Mokhov, N.V.; Tropin, I.S.; Zwaska, R.; /Fermilab

    2012-05-01

    Severe limits are put on allowable beam loss during extraction and transport of a 2.3 MW primary proton beam for the Long Baseline Neutrino Experiment (LBNE) at Fermilab. Detailed simulations with the STRUCT and MARS codes have evaluated the impact of beam loss of 1.6 x 10{sup 14} protons per pulse at 120 GeV, ranging from a single pulse full loss to sustained small fractional loss. It is shown that loss of a single beam pulse at 2.3 MW will result in a catastrophic event: beam pipe destruction, damaged magnets and very high levels of residual radiation inside and outside the tunnel. Acceptable beam loss limits have been determined and robust solutions developed to enable efficient proton beam operation under these constraints.

  17. Measurements of Beam Ion Loss from the Compact Helical System

    SciTech Connect

    D. S. Darrow, M. Isobe, Takashi Kondo, M. Sasao, and the CHS Group National Institute for Fusion Science, Toki, Gifu, Japan

    2010-02-03

    Beam ion loss from the Compact Helical System (CHS) has been measured with a scintillator-type probe. The total loss to the probe, and the pitch angle and gyroradius distributions of that loss, have been measured as various plasma parameters were scanned. Three classes of beam ion loss were observed at the probe position: passing ions with pitch angles within 10o of those of transition orbits, ions on transition orbits, and ions on trapped orbits, typically 15o or more from transition orbits. Some orbit calculations in this geometry have been performed in order to understand the characteristics of the loss. Simulation of the detector signal based upon the following of orbits from realistic beam deposition profiles is not able to reproduce the pitch angle distribution of the losses measured. Consequently it is inferred that internal plasma processes, whether magnetohydrodynamic modes, radial electric fields, or plasma turbulence, move previously confined beam ions to transition orbits, resulting in their loss.

  18. Cavity loss factors for non-ultrarelativistic beams

    SciTech Connect

    Kurennoy, S.S.

    1998-12-31

    Cavity loss factors can be easily computed for ultrarelativistic beams using time-domain codes like MAFIA or ABCI. However, for non-ultrarelativistic beams the problem is more complicated because of difficulties with its numerical formulation in the time domain. The authors calculate the loss factors of a non-relativistic bunch and compare results with the relativistic case.

  19. Design for controllable optofluidic beam splitter

    NASA Astrophysics Data System (ADS)

    Tang, Xionggui; Liang, Shan; Li, Rujian

    2016-01-01

    A novel configuration for controllable optofluidic beam splitter is proposed, which consists of the asymmetric Y-branch waveguide and the microfluidic channel filled with fluid mixture. The beam propagation method (BPM) is employed to numerically investigate the optical performance of device in our layout. The simulated results demonstrate that arbitrary splitting ratio and low optical loss for both TE and TM mode can be easily achieved, with a low dependence of wavelength and polarization. Particularly, the optofluidic beam splitter has advantages such as compact structure and large fabrication tolerance. The proposed device provides a new way to manipulate the optical power splitting, and has wide potential applications in integrated optofluidic system.

  20. A Flexible, Low Cost, Beam Loss Monitor Evaluation System

    SciTech Connect

    Hoyes, George Garnet; Pimol, Piti; Juthong, Nawin; Attaphibal, Malee

    2007-01-19

    A flexible, low cost, Beam Loss Monitor (BLM) Evaluation System based on Bergoz BLMs has been developed. Monitors can easily be moved to any location for beam loss investigations and/or monitor usefulness evaluations. Different PC pulse counting cards are compared and tested for this application using the display software developed based on LabVIEW. Beam problems uncovered with this system are presented.

  1. Anomaly Detection for Beam Loss Maps in the Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Valentino, Gianluca; Bruce, Roderik; Redaelli, Stefano; Rossi, Roberto; Theodoropoulos, Panagiotis; Jaster-Merz, Sonja

    2017-07-01

    In the LHC, beam loss maps are used to validate collimator settings for cleaning and machine protection. This is done by monitoring the loss distribution in the ring during infrequent controlled loss map campaigns, as well as in standard operation. Due to the complexity of the system, consisting of more than 50 collimators per beam, it is difficult to identify small changes in the collimation hierarchy, which may be due to setting errors or beam orbit drifts with such methods. A technique based on Principal Component Analysis and Local Outlier Factor is presented to detect anomalies in the loss maps and therefore provide an automatic check of the collimation hierarchy.

  2. H- AND PROTON BEAM LOSS COMPARISON AT SNS SUPERCONDUCTING LINAC

    SciTech Connect

    Aleksandrov, Alexander V; Galambos, John D; Plum, Michael A; Shishlo, Andrei P

    2012-01-01

    A comparison of beam loss in the superconducting part (SCL) of the Spallation Neutron Source (SNS) linac for H- and protons is presented. During the experiment the nominal beam of negative hydrogen ions in the SCL was replaced by a proton beam created by insertion of a thin stripping carbon foil placed in the low energy section of the linac. The observed significant reduction in the beam loss for protons is explained by a domination of the intra beam stripping mechanism of the beam loss for H-. The details of the experiment are discussed, and a preliminary estimation of the cross section of the reaction H- + H- -> H- + H0 + e is presented. Earlier, a short description of these studies was presented in [1].

  3. Maximum Beam Power and Nominal Beam Losses at S-20

    SciTech Connect

    Clendenin, J.

    2005-01-31

    The maximum credible beam power values for electrons shown in Table 1 for e{sup -} beams are based on a beam power of 1.8 MW (1.875 x 10{sup 12} e{sup -} at 120 Hz) for an energy of 50 GeV at S-30. Positrons are limited by the positron source damage threshold to an average current of {approx}2 {mu}A, i.e., {approx}10{sup 11} e{sup -} per pulse at 120 Hz on the target [1]. The ratio of e{sup +} at S-1 per e{sup -} on the conversion target is {ge}2. At S-20 the maximum linac energy is 33 GeV, while the HER and LER Bypass beams are limited to 12 and 4 GeV respectively by the BCS.

  4. The LCLS Undulator Beam Loss Monitor Readout System

    SciTech Connect

    Dusatko, John; Browne, M.; Fisher, A.S.; Kotturi, D.; Norum, S.; Olsen, J.; /SLAC

    2012-07-23

    The LCLS Undulator Beam Loss Monitor System is required to detect any loss radiation seen by the FEL undulators. The undulator segments consist of permanent magnets which are very sensitive to radiation damage. The operational goal is to keep demagnetization below 0.01% over the life of the LCLS. The BLM system is designed to help achieve this goal by detecting any loss radiation and indicating a fault condition if the radiation level exceeds a certain threshold. Upon reception of this fault signal, the LCLS Machine Protection System takes appropriate action by either halting or rate limiting the beam. The BLM detector consists of a PMT coupled to a Cherenkov radiator located near the upstream end of each undulator segment. There are 33 BLMs in the system, one per segment. The detectors are read out by a dedicated system that is integrated directly into the LCLS MPS. The BLM readout system provides monitoring of radiation levels, computation of integrated doses, detection of radiation excursions beyond set thresholds, fault reporting and control of BLM system functions. This paper describes the design, construction and operational performance of the BLM readout system.

  5. Modeling process of the neutral beam re-ionization loss

    NASA Astrophysics Data System (ADS)

    Liang, Li-Zhen; Hu, Chun-Dong; Xie, Yuan-Lai; Xie, Ya-Hong; Nbi-team

    2010-07-01

    The basic process of re-ionization loss was studied. In the drift duct there are three processes leading to re-ionization loss: the collision of neutral beam particles with the molecules of background gas, similar collisions with released molecules from the inner wall of the drift duct and the ferret-collisions among particles with different energy of the neutral beam. Mathematical models have been developed and taking EAST-NBI parameters as an example, the re-ionization loss was obtained within these models. The result indicated that in the early stage of the neutral beam injector operation the released gas was quite abundant. The amount of re-ionization loss owing to the released gas can be as high as 60%. In the case of a long-time operation of the neutral beam injector, the total re-ionization loss decreases from 13.7% to 5.7%. Then the reionization loss originating mainly from the collisions between particles of the neutral beam and the background molecules is dominant, covering about 92% of the total re-ionization loss. The drift duct pressure was the decisive factor for neutral beam re-ionization loss.

  6. Tolerable Beam Loss at High-Intensity Machines

    SciTech Connect

    Oleg E. Krivosheev, Nikolai V. Mokhov

    2000-08-28

    Tolerable beam losses are estimated for high-intensity ring accelerators with proton energy of 3 to 16 GeV. Dependence on beam energy, lattice and magnet geometry is studied via full Monte Carlo MARS14 simulations in lattice elements, shielding, tunnel and surrounding dirt with realistic geometry, materials and magnetic fields.

  7. Dependence of bunch energy loss in cavities on beam velocity

    NASA Astrophysics Data System (ADS)

    Kurennoy, Sergey S.

    1999-03-01

    Beam energy loss in a cavity can be easily computed for a relativistic bunch using time-domain codes like MAFIA or ABCI. However, for nonrelativistic beams the problem is more complicated because of difficulties with its numerical formulation in the time domain. We calculate the cavity loss factors for a bunch in frequency domain as a function of its velocity and compare results with the relativistic case.

  8. Beam Loss Monitors in the NSLS Storage Rings

    SciTech Connect

    Kramer,S.L.; Fedurin, M.

    2009-05-04

    Beam loss monitors (BLM) have been used for more than two decades in the VUV ring at the NSLS. These have proved useful for optimizing injection and operation of the ring. Recently similar monitors have been installed in the X-ray ring and are being used to better understand injection, as well as operation of the ring. These units have been compared with the Bergoz BLMs, which have been mostly useful for understanding operating beam losses.

  9. Beam Losses in the NLC Extraction Line for High Luminosity Beam Parameters (LCC-0049)

    SciTech Connect

    Nosochkov, Y

    2004-03-19

    In this note we present results of beam tracking in the NLC extraction line for the NLC option with high luminosity beam parameters (option H). Particle losses for 0.5 TeV and 1 TeV cms energy beams have been computed and examined as a function of beam offset at the interaction point (IP). Updated tracking results for the NLC option A are presented as well.

  10. Aircraft Loss of Control Study

    NASA Technical Reports Server (NTRS)

    Jacobson, Steven R.

    2010-01-01

    Loss of control has become the leading cause of jet fatalities worldwide. Aside from their frequency of occurrence, accidents resulting from loss of aircraft control seize the public s attention by yielding large numbers of fatalities in a single event. In response to the rising threat to aviation safety, NASA's Aviation Safety Program has conducted a study of the loss of control problem. This study gathered four types of information pertaining to loss of control accidents: (1) statistical data; (2) individual accident reports that cite loss of control as a contributing factor; (3) previous meta-analyses of loss of control accidents; and (4) inputs solicited from aircraft manufacturers, air carriers, researchers, and other industry stakeholders. Using these information resources, the study team identified causal factors that were cited in the greatest number of loss of control accidents, and which were emphasized most by industry stakeholders. For each causal factor that was linked to loss of control, the team solicited ideas about what solutions are required and future research efforts that could potentially help avoid their occurrence or mitigate their consequences when they occurred in flight.

  11. Beam/seam alignment control for electron beam welding

    DOEpatents

    Burkhardt, Jr., James H.; Henry, J. James; Davenport, Clyde M.

    1980-01-01

    This invention relates to a dynamic beam/seam alignment control system for electron beam welds utilizing video apparatus. The system includes automatic control of workpiece illumination, near infrared illumination of the workpiece to limit the range of illumination and camera sensitivity adjustment, curve fitting of seam position data to obtain an accurate measure of beam/seam alignment, and automatic beam detection and calculation of the threshold beam level from the peak beam level of the preceding video line to locate the beam or seam edges.

  12. Analysis ob beam losses at PSR (Proton Storage Ring)

    SciTech Connect

    Macek, R.J.; Fitzgerald, D.H.; Hutson, R.L.; Plum, M.A.; Thiessen, H.A.

    1988-01-01

    Beam losses and the resulting component activation at the Los Alamos Proton Storage Ring (PSR) have limited operating currents to about 30..mu..A average at a repetition rate of 15 Hz. Loss rates were found to be approximately proportional to the circulating current and can be understood by a detailed accounting of emittance growth in the two step injection process along with Coulomb scattering of the stored beam during multiple traversals of the injection foil. Calculations and simulations of the losses are in reasonable agreement with measurements.

  13. MHD Induced Neutral Beam Ion Loss from NSTX Plasmas

    SciTech Connect

    D.S. Darrow, E.D. Fredrickson, N.N. Gorelenkov, A.L. Roquemore, and K. Shinohara

    2007-12-13

    Bursts of ~60 kHz activity on Mirnov coils occur frequently in NSTX plasmas and these are accompanied by bursts of neutral beam ion loss over a range in pitch angles. These losses have been measured with a scintillator type loss probe imaged with a high speed (>10,000 frames/s) video camera, giving the evolution of the energy and pitch angle distributions of the lost neutral beam ions over the course of the events. The instability occurs below the TAE frequency in NSTX (~100 kHz) in high beta plasmas and may be a beta driven Alfvén acoustic (BAAE) mode.

  14. Laser-Beam-Alignment Controller

    NASA Technical Reports Server (NTRS)

    Krasowski, M. J.; Dickens, D. E.

    1995-01-01

    In laser-beam-alignment controller, images from video camera compared to reference patterns by fuzzy-logic pattern comparator. Results processed by fuzzy-logic microcontroller, which sends control signals to motor driver adjusting lens and pinhole in spatial filter.

  15. Implementation of Beam-Loss Monitor systems for the SSC

    SciTech Connect

    Johnson, R.G.

    1994-07-01

    Beam-Loss Monitors (BLM) are used with each accelerator in the Superconducting Super Collider complex. The primary purpose of these detectors is to protect the accelerators from damage due to the loss of protons. Although the range of primary beam energies to be covered is very large, 20 MeV to 20 TeV, we plan to maintain commonality of detectors and electronics as much as possible. In this report the plans for developing and implementing BLM systems for each of the accelerators will be discussed. Possible solutions to problems that have been identified are presented.

  16. Microelectromechanical (MEMS) optical beam control

    NASA Astrophysics Data System (ADS)

    Laurvick, Tod; Starman, LaVern; Coutu, Ronald, Jr.

    2009-08-01

    This experiment explores the manufacturability of controllable Micro-electromechanical (MEMS) mirrors to direct optical signals. Design includes four separate mirrors which independently control vertical displacement, horizontal displacement, vertical pitch and horizontal pitch. Such devices could be used for a variety of applications but were specifically intended for future use in communications between optical based circuits residing on separate chips. Prototype devices were built in PolyMUMPs to test the feasibility of this process for applications such as this, including a full outgoing beam path with mirror orientations and actuation designs to accomplish this. Several elements of this outgoing beam path were successful and those which needed improvement indicate a high probability of success with limited trials needed. Improvement recommendations on currently successful design elements which could still be improved within the scope of PolyMUMPs have been identified. Originally intended only to direct the outgoing beam, this design could be used on the incoming path as well. Such a design would ensure that the receiving device only requires a target location and not that a specific incoming vector be obtained. This would thus comprise all the elements needed for a prototype proof of concept device to be built. More sophisticated fabrication processes could provide drastic improvements to both transmission and reception beam paths and potentially allow for a variety of more sophisticated designs to improve compactness, controllability, tighten tolerances on moving parts, increase mirror quality, and improved productivity of large quantities of devices.

  17. beam loss scenarios for MuCool Test Area

    SciTech Connect

    Rakhno, Igor; Johnstone, Carol; /Fermilab

    2010-08-01

    The MuCool Test Area (MTA) is an intense primary beam facility derived directly from the Fermilab Linac to test heat deposition and other technical concerns associated with the liquid hydrogen targets, gas-filled RF cavities, and other apparatus being developed to cool intense, large-emittance muon beams. In this study the results of Monte Carlo modeling of several beam loss scenarios are presented. The MTA facility was designed to test targets and other muon cooling apparatus using the intense Fermilab Linac beam. The requested intensity of the proton beam for the MTA is essentially full Linac capability, or 1.6 x 10{sup 13} protons per pulse and an energy of 400 MeV. Two modes of operation will be supported in the MuCOOL beamline: one mode for emittance measurements (and beamline studies) and a second mode for MTA experiments. Maximum beam intensity for these two modes is: 9.6 x 10{sup 15} protons/hr - 600 beam pulses/hour of full Linac beam pulse intensity (1.6 x 10{sup 13} protons/pulse) to the emittance beam absorber and 9.6 x 10{sup 14} protons/hour - 60 beam pulses/hour of full Linac beam pulse intensity to experiments in the MTA experimental hall. This extremely high intensity implies careful investigation into and application of proper shielding materials and configuration in order to satisfy the following two requirements: (i) to reduce the instantaneous dose rate outside of the experimental enclosure to prescribed levels appropriate for the area considered; (ii) to ensure the civil construction of the hall is capable of additional shielding and, further, that the weight of the shielding is commensurate with the loading specifications of the enclosure, notably the ceiling. A number of scenarios for beam loss at different locations were studied in order to determine the maximum beam intensity which is in compliance with the existing shielding. The modeling was performed with the MARS15 code.

  18. New Beam Loss Monitor for 12 GeV Upgrade

    SciTech Connect

    Jianxun Yan, Kelly Mahoney

    2009-10-01

    This paper describes a new VME based machine protection Beam Loss Monitor (BLM) signal processing board designed at Jefferson Lab to replace the current CAMAC based BLM board. The new eight-channel BLM signal processor has linear, logarithmic, and integrating amplifiers that simultaneously provide the optimal signal processing for each application. Amplified signals are digitized and then further processed through a Field Programmable Gate Array (FPGA). Combining both the diagnostic and machine protection functions in each channel allows the operator to tune-up and monitor beam operations while the machine protection is integrating the same signal. Other features include extensive built-in-self-test, fast shutdown interface (FSD), and 16-Mbit buffers for beam loss transient play-back. The new VME BLM board features high sensitivity, high resolution, and low cost per channel.

  19. Beam Loss and Longitudinal Emittance Growth in SIS

    NASA Astrophysics Data System (ADS)

    Kirk, M.; Hofmann, I.; Boine-Frankenheim, O.; Spiller, P.; Hülsmann, P.; Franchetti, G.; Damerau, H.; König, H. Günter; Klingbeil, H.; Kumm, M.; Moritz, P.; Schütt, P.; Redelbach, A.

    2005-06-01

    Beam losses of several percent occur regularly in SIS. The onset occurs during the RF capture of the beam. Previous studies have revealed that the losses can come from the RF bucket at the start of acceleration being over filled due to the longitudinal bucket acceptance being too small, or due to the mismatch between the mean energy from the UNILAC and synchronous energy of the SIS. The beam losses as measured by a DC beam transformer however show in addition to the sharp initial drop, for the above reasons, a much slower decay in the beam intensity. The speculated cause comes from the incoherent transverse tune shift of the bunched beam, which forces particles into transverse resonant conditions. The longitudinal emittance growth is also another important issue for SIS. Past measurements from Schottky-noise pick-ups have shown a factor of 3-5 increase in the longitudinal emittance depending on the extraction energy; a large factor when compared against expectations from theory. These factors were calculated from the ratio between the normalized relative momentum spread of the DC beam before RF capture and after debunching. In this present work, tomographical techniques have been used to reconstruct the phasespace from a series of bunch profile measurements from a Beam Position Monitor (BPM). Therefore one can find the rate of growth in the longitudinal emittance from a series of high resolution BPM measurements along the RF ramp. Furthermore the initial phasespace density matrix from these reconstructions has been used to generate the initial population of macroparticles for the ESME longitudinal dynamics Particle-In-Cell code, thereby enabling a comparison between the longitudinal emittance growth of the beam under ideal conditions and that of the experiment. The longitudinal emittance growth (rms) during the acceleration (˜540ms) was approximately 20%, and that during the RF capture was estimated to have an upper limit of about 40%. Later measurements have also

  20. A microcomputer-controlled laser beam analyzer

    NASA Astrophysics Data System (ADS)

    Hand, L. E.; Nagle, H. T., Jr.; Kerns, D. V., Jr.

    1982-07-01

    A microcomputer-controlled laser beam analyzer is described. It uses five INTEL 8080 microcomputers to calculate the beam's peak intensity, peak intensity coordinates, centroid coordinates, beam energy, and beam quality in real time. Its application to the U.S. Army's gas-dynamic laser is illustrated.

  1. RFQ Designs and Beam-Loss Distributions for IFMIF

    SciTech Connect

    Jameson, Robert A

    2007-01-01

    The IFMIF 125 mA cw 40 MeV accelerators will set an intensity record. Minimization of particle loss along the accelerator is a top-level requirement and requires sophisticated design intimately relating the accelerated beam and the accelerator structure. Such design technique, based on the space-charge physics of linear accelerators (linacs), is used in this report in the development of conceptual designs for the Radio-Frequency-Quadrupole (RFQ) section of the IFMIF accelerators. Design comparisons are given for the IFMIF CDR Equipartitioned RFQ, a CDR Alternative RFQ, and new IFMIF Post-CDR Equipartitioned RFQ designs. Design strategies are illustrated for combining several desirable characteristics, prioritized as minimum beam loss at energies above ~ 1 MeV, low rf power, low peak field, short length, high percentage of accelerated particles. The CDR design has ~0.073% losses above 1 MeV, requires ~1.1 MW rf structure power, has KP factor 1.7,is 12.3 m long, and accelerates ~89.6% of the input beam. A new Post-CDR design has ~0.077% losses above 1 MeV, requires ~1.1 MW rf structure power, has KP factor 1.7 and ~8 m length, and accelerates ~97% of the input beam. A complete background for the designs is given, and comparisons are made. Beam-loss distributions are used as input for nuclear physics simulations of radioactivity effects in the IFMIF accelerator hall, to give information for shielding, radiation safety and maintenance design. Beam-loss distributions resulting from a ~1M particle input distribution representative of the IFMIF ECR ion source are presented. The simulations reported were performed with a consistent family of codes. Relevant comparison with other codes has not been possible as their source code is not available. Certain differences have been noted but are not consistent over a broad range of designs and parameter range. The exact transmission found by any of these codes should be treated as indicative, as each has various sensitivities in

  2. Beam losses and beam halos in accelerators for new energy sources

    SciTech Connect

    Jameson, R.A.

    1995-12-31

    Large particle accelerators are proposed as drivers for new ways to produce electricity from nuclear fusion and fission reactions. The accelerators must be designed to deliver large particle beam currents to a target facility with very little beam spill along the accelerator itself, in order that accelerator maintenance can be accomplished without remote manipulators. Typically, particle loss is preceded by the formation of a tenuous halo of particles around the central beam core, caused by beam dynamics effects, often coupled with the slight imperfections inevitable in a practical design. If the halo becomes large enough, particles may be scraped off along the accelerator. The tolerance for beam spill in different applications is discussed, halo mechanisms and recent work to explore and understand their dynamics are reviewed, and possible directions for future investigation are outlined. 17 refs., 10 figs.

  3. Proton beam therapy control system

    DOEpatents

    Baumann, Michael A [Riverside, CA; Beloussov, Alexandre V [Bernardino, CA; Bakir, Julide [Alta Loma, CA; Armon, Deganit [Redlands, CA; Olsen, Howard B [Colton, CA; Salem, Dana [Riverside, CA

    2008-07-08

    A tiered communications architecture for managing network traffic in a distributed system. Communication between client or control computers and a plurality of hardware devices is administered by agent and monitor devices whose activities are coordinated to reduce the number of open channels or sockets. The communications architecture also improves the transparency and scalability of the distributed system by reducing network mapping dependence. The architecture is desirably implemented in a proton beam therapy system to provide flexible security policies which improve patent safety and facilitate system maintenance and development.

  4. Proton beam therapy control system

    DOEpatents

    Baumann, Michael A.; Beloussov, Alexandre V.; Bakir, Julide; Armon, Deganit; Olsen, Howard B.; Salem, Dana

    2010-09-21

    A tiered communications architecture for managing network traffic in a distributed system. Communication between client or control computers and a plurality of hardware devices is administered by agent and monitor devices whose activities are coordinated to reduce the number of open channels or sockets. The communications architecture also improves the transparency and scalability of the distributed system by reducing network mapping dependence. The architecture is desirably implemented in a proton beam therapy system to provide flexible security policies which improve patent safety and facilitate system maintenance and development.

  5. Proton beam therapy control system

    DOEpatents

    Baumann, Michael A; Beloussov, Alexandre V; Bakir, Julide; Armon, Deganit; Olsen, Howard B; Salem, Dana

    2013-06-25

    A tiered communications architecture for managing network traffic in a distributed system. Communication between client or control computers and a plurality of hardware devices is administered by agent and monitor devices whose activities are coordinated to reduce the number of open channels or sockets. The communications architecture also improves the transparency and scalability of the distributed system by reducing network mapping dependence. The architecture is desirably implemented in a proton beam therapy system to provide flexible security policies which improve patent safety and facilitate system maintenance and development.

  6. Proton beam therapy control system

    DOEpatents

    Baumann, Michael A; Beloussov, Alexandre V; Bakir, Julide; Armon, Deganit; Olsen, Howard B; Salem, Dana

    2013-12-03

    A tiered communications architecture for managing network traffic in a distributed system. Communication between client or control computers and a plurality of hardware devices is administered by agent and monitor devices whose activities are coordinated to reduce the number of open channels or sockets. The communications architecture also improves the transparency and scalability of the distributed system by reducing network mapping dependence. The architecture is desirably implemented in a proton beam therapy system to provide flexible security policies which improve patent safety and facilitate system maintenance and development.

  7. INCREASED UNDERSTANDING OF BEAM LOSSES FROM THE SNS LINAC PROTON EXPERIMENT

    SciTech Connect

    Aleksandrov, Alexander V; Shishlo, Andrei P; Plum, Michael A; Lebedev, Valerie; Laface, Emanuele; Galambos, John D

    2013-01-01

    Beam loss is a major concern for high power hadron accelerators such as the Spallation Neutron Source (SNS). An unexpected beam loss in the SNS superconducting linac (SCL) was observed during the power ramp up and early operation. Intra-beam-stripping (IBS) loss, in which interactions between H- particles within the accelerated bunch strip the outermost electron, was recently identified as a possible cause of the beam loss. A set of experiments using proton beam acceleration in the SNS linac was conducted, which supports IBS as the primary beam loss mechanism in the SNS SCL.

  8. Simulations and measurements of beam loss patterns at the CERN Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Bruce, R.; Assmann, R. W.; Boccone, V.; Bracco, C.; Brugger, M.; Cauchi, M.; Cerutti, F.; Deboy, D.; Ferrari, A.; Lari, L.; Marsili, A.; Mereghetti, A.; Mirarchi, D.; Quaranta, E.; Redaelli, S.; Robert-Demolaize, G.; Rossi, A.; Salvachua, B.; Skordis, E.; Tambasco, C.; Valentino, G.; Weiler, T.; Vlachoudis, V.; Wollmann, D.

    2014-08-01

    The CERN Large Hadron Collider (LHC) is designed to collide proton beams of unprecedented energy, in order to extend the frontiers of high-energy particle physics. During the first very successful running period in 2010-2013, the LHC was routinely storing protons at 3.5-4 TeV with a total beam energy of up to 146 MJ, and even higher stored energies are foreseen in the future. This puts extraordinary demands on the control of beam losses. An uncontrolled loss of even a tiny fraction of the beam could cause a superconducting magnet to undergo a transition into a normal-conducting state, or in the worst case cause material damage. Hence a multistage collimation system has been installed in order to safely intercept high-amplitude beam protons before they are lost elsewhere. To guarantee adequate protection from the collimators, a detailed theoretical understanding is needed. This article presents results of numerical simulations of the distribution of beam losses around the LHC that have leaked out of the collimation system. The studies include tracking of protons through the fields of more than 5000 magnets in the 27 km LHC ring over hundreds of revolutions, and Monte Carlo simulations of particle-matter interactions both in collimators and machine elements being hit by escaping particles. The simulation results agree typically within a factor 2 with measurements of beam loss distributions from the previous LHC run. Considering the complex simulation, which must account for a very large number of unknown imperfections, and in view of the total losses around the ring spanning over 7 orders of magnitude, we consider this an excellent agreement. Our results give confidence in the simulation tools, which are used also for the design of future accelerators.

  9. ISABELLE accelerator software, control system, and beam diagnostic philosophy

    SciTech Connect

    Cornacchia, M.; Humphrey, J.W.; Niederer, J.; Poole, J.H.

    1981-01-01

    The ISABELLE Project combines two large proton accelerators with two storage rings in the same facility using superconducting magnet technology. This combination leads to severe constraints on beam loss in magnets and involves complex treatment of magnetic field imperfections and correction elements. The consequent demands placed upon beam diagnostics, accelerator model programs, and the computer oriented control system are discussed in terms of an illustrative operation scenario.

  10. Prompt loss of beam ions in KSTAR plasmas

    NASA Astrophysics Data System (ADS)

    Kim, Jun Young; Rhee, T.; Kim, Junghee; Yoon, S. W.; Park, B. H.; Isobe, M.; Ogawa, K.; Ko, W.-H.

    2016-10-01

    For a toroidal plasma facility to realize fusion energy, researching the transport of fast ions is important not only due to its close relation to the heating and current drive efficiencies but also to determine the heat load on the plasma-facing components. We present a theoretical analysis and orbit simulation for the origin of lost fast-ions during neutral beam injection (NBI) heating in Korea Superconducting Tokamak Advanced Research (KSTAR) device. We adopted a two-dimensional phase diagram of the toroidal momentum and magnetic moment and describe detectable momentums at the fast-ion loss detector (FILD) position as a quadratic line. This simple method was used to model birth ions deposited by NBI and drawn as points in the momentum phase space. A Lorentz orbit code was used to calculate the fast-ion orbits and present the prompt loss characteristics of the KSTAR NBI. The scrape-off layer deposition of fast ions produces a significant prompt loss, and the model and experimental results closely agreed on the pitch-angle range of the NBI prompt loss. Our approach can provide wall load information from the fast ion loss.

  11. Three-dimensional particle trajectories and waste beam losses in injection dump beam line of SNS accumulator ring

    SciTech Connect

    Wang, Jian-Guang; Plum, Michael A

    2008-01-01

    The SNS ring injection dump beam line has been suffering high beam losses since its commissioning. In order to understand the mechanisms of the beam losses, we have performed 3D simulation studies of the beam line. The 3D models consist of three injection chicane dipoles and one injection dump septum magnet. 3D particle trajectories in the models are computed. We then extend particle optics calculations to the injection dump. Our studies have clearly shown some design and operation problems, that cause beam losses in the injection dump beam line. These include incorrect chicane dipole settings, incorrect position of a chicane dipole, too small aperture of injection dump septum, and inadequate focusing downstream. This paper reports our findings and the remedies to the injection beam loss problems.

  12. Recording PEP2 Ring Beam Losses at SLAC

    SciTech Connect

    Zelazny, M.; Gromme, T.; Himel, T.; Hendrickson, L.; Krauter, K.; /SLAC

    2005-09-30

    The PEP2 (e+)(e-) storage rings contain many complex interrelated systems. When the beam aborts, examining a record of the orbit from the time just before the abort can help identify the root cause. At the Stanford Linear Accelerator Center (SLAC) a system has been developed to continuously record beam orbits from Beam Position Monitors (BPMS) into a circular buffer. When the beam is aborted the buffers are frozen and their contents are stored for later analysis. BPM orbits are saved on a turn by turn basis for 2800 turns in both the high energy ring (HER) and the low energy ring (LER). Each BPM Processor (BPMP) can either monitor the HER or the LER, but not both as the readout of the two rings is multiplexed into a single readout channel. Tools exist as part of the SLAC Control Program (SCP) to collect, display, and save the data. A physicist or operator can choose a few BPMS in which to view all 2800 turns to identify the turn in which the beam went awry; then ask for that specific orbit from all of the BPMS in the storage ring to determine the root cause of the abort.

  13. Moyer model approximations for point and extended beam losses

    NASA Astrophysics Data System (ADS)

    McCaslin, Joseph B.; Swanson, William P.; Thomas, Ralph H.

    1987-05-01

    The use of the empirical Moyer model for the determination of transverse neutron shielding for high-energy proton accelerators is described and discussed. It is shown that an important advantage of the Moyer Model is the physical insight it offers towards understanding the complex interactions that comprise the shielding processes. Calculations for pointlike and extended uniform beam loss distributions are discussed and their relationship to practical shielding conditions developed. The calculations required by the model are readily performed on small programmable calculators and thus are widely accessible. Program listings for practical calculations using a Hewlett-Packard HP-97 calculator are available on request.

  14. The use of photographic film to pinpoint accelerator beam losses.

    PubMed

    Marceau-Day, Marie Lorraine; Teague, Richard E; Wang, Wei-Hsung

    2011-08-01

    Following removal of a superconducting wiggler that has a maximum magnetic-field of 7 T in a high-energy synchrotron facility, sufficient lead shielding was placed upstream of the removal point in the normal-conducting electron storage ring to account for any radiation sources from the upstream components. As is customary in such cases, when vacuum has been breached, there is a period of time required for vacuum re-conditioning of the ring. During this re-conditioning phase, poor vacuum contributes to gas bremsstrahlung formation that typically is visualized as an increase in overall radiation exposure from standard operating conditions. However, in this case, new radiation patterns emerged and persisted throughout the re-commissioning phase. Subsequently, additional shielding was then placed upstream but still failed to resolve the source of radiation. The radiation source point consisted of two distinct components: a point parallel to the position originally covered by the wiggler and a strong forward-directed peak (i.e., bremsstrahlung). The only feedback mechanism to track the beam position is the beam position monitors (BPM's). BPM's were located forward and aft of the parallel source point. The BPM's suggested that the beam was in the correct position. To investigate the elevated radiation level, commercial photographic film was used as a monitoring ruler and the focal point of the radiation source was clearly identified using this novel approach. The silver halide grain contained within the film emulsion possessed sufficient cross section and was activated from Ag to Ag, which has a half-life of 2.39 min and emits easily detectable radiation. Further, the exposed film is ready for reuse after 25 min due to the short half-life of Ag. The proposed method proved to be an easy, economic, and effective approach to rapidly and qualitatively identify the location of the beam losses.

  15. A new beam loss detector for low-energy proton and heavy-ion accelerators

    NASA Astrophysics Data System (ADS)

    Liu, Zhengzheng; Crisp, Jenna; Russo, Tom; Webber, Robert; Zhang, Yan

    2014-12-01

    The Facility for Rare Isotope Beams (FRIB) to be constructed at Michigan State University shall deliver a continuous, 400 kW heavy ion beam to the isotope production target. This beam is capable of inflicting serious damage on accelerator components, e.g. superconducting RF accelerating cavities. A Beam Loss Monitoring (BLM) System is essential for detecting beam loss with sufficient sensitivity and promptness to inform the machine protection system (MPS) and operations personnel of impending dangerous losses. Radiation transport simulations reveal shortcomings in the use of ionization chambers for the detection of beam losses in low-energy, heavy-ion accelerators. Radiation cross-talk effects due to the folded geometry of the FRIB LINAC pose further complications to locating specific points of beam loss. We propose a newly developed device, named the Loss Monitor Ring (LMR1

  16. Loss of balance during balance beam walking elicits a multifocal theta band electrocortical response

    PubMed Central

    Gwin, Joseph T.; Makeig, Scott; Ferris, Daniel P.

    2013-01-01

    Determining the neural correlates of loss of balance during walking could lead to improved clinical assessment and treatment for individuals predisposed to falls. We used high-density electroencephalography (EEG) combined with independent component analysis (ICA) to study loss of balance during human walking. We examined 26 healthy young subjects performing heel-to-toe walking on a treadmill-mounted balance beam as well as walking on the treadmill belt (both at 0.22 m/s). ICA identified clusters of electrocortical EEG sources located in or near anterior cingulate, anterior parietal, superior dorsolateral-prefrontal, and medial sensorimotor cortex that exhibited significantly larger mean spectral power in the theta band (4–7 Hz) during walking on the balance beam compared with treadmill walking. Left and right sensorimotor cortex clusters produced significantly less power in the beta band (12–30 Hz) during walking on the balance beam compared with treadmill walking. For each source cluster, we also computed a normalized mean time/frequency spectrogram time locked to the gait cycle during loss of balance (i.e., when subjects stepped off the balance beam). All clusters except the medial sensorimotor cluster exhibited a transient increase in theta band power during loss of balance. Cluster spectrograms demonstrated that the first electrocortical indication of impending loss of balance occurred in the left sensorimotor cortex at the transition from single support to double support prior to stepping off the beam. These findings provide new insight into the neural correlates of walking balance control and could aid future studies on elderly individuals and others with balance impairments. PMID:23926037

  17. Loss of balance during balance beam walking elicits a multifocal theta band electrocortical response.

    PubMed

    Sipp, Amy R; Gwin, Joseph T; Makeig, Scott; Ferris, Daniel P

    2013-11-01

    Determining the neural correlates of loss of balance during walking could lead to improved clinical assessment and treatment for individuals predisposed to falls. We used high-density electroencephalography (EEG) combined with independent component analysis (ICA) to study loss of balance during human walking. We examined 26 healthy young subjects performing heel-to-toe walking on a treadmill-mounted balance beam as well as walking on the treadmill belt (both at 0.22 m/s). ICA identified clusters of electrocortical EEG sources located in or near anterior cingulate, anterior parietal, superior dorsolateral-prefrontal, and medial sensorimotor cortex that exhibited significantly larger mean spectral power in the theta band (4-7 Hz) during walking on the balance beam compared with treadmill walking. Left and right sensorimotor cortex clusters produced significantly less power in the beta band (12-30 Hz) during walking on the balance beam compared with treadmill walking. For each source cluster, we also computed a normalized mean time/frequency spectrogram time locked to the gait cycle during loss of balance (i.e., when subjects stepped off the balance beam). All clusters except the medial sensorimotor cluster exhibited a transient increase in theta band power during loss of balance. Cluster spectrograms demonstrated that the first electrocortical indication of impending loss of balance occurred in the left sensorimotor cortex at the transition from single support to double support prior to stepping off the beam. These findings provide new insight into the neural correlates of walking balance control and could aid future studies on elderly individuals and others with balance impairments.

  18. Loss of accuracy using smeared properties in composite beam modeling

    NASA Astrophysics Data System (ADS)

    Liu, Ning

    Advanced composite materials have broad, proven applications in many engineering systems ranging from sports equipment sectors to components on the space shuttle because of their lightweight characteristics and significantly high stiffness. Together with this merit of composite materials is the challenge of improving computational simulation process for composites analysis. Composite structures, particularly composite laminates, usually consist of many layers with different lay-up angles. The anisotropic and heterogeneous features render 3D finite element analysis (FEA) computationally expensive in terms of the computational time and the computing power. At the constituent level, composite materials are heterogeneous. But quite often one homogenizes each layer of composites, i.e. lamina, and uses the homogenized material properties as averaged (smeared) values of those constituent materials for analysis. This is an approach extensively used in design and analysis of composite laminates. Furthermore, many industries tempted to use smeared properties at the laminate level to further reduce the model of composite structures. At this scale, smeared properties are averaged material properties that are weighted by the layer thickness. Although this approach has the advantage of saving computational time and cost of modeling significantly, the prediction of the structural responses may not be accurate, particularly the pointwise stress distribution. Therefore, it is important to quantify the loss of accuracy when one uses smeared properties. In this paper, several different benchmark problems are carefully investigated in order to exemplify the effect of the smeared properties on the global behavior and pointwise stress distribution of the composite beam. In the classical beam theory, both Newtonian method and variational method include several ad hoc assumptions to construct the model, however, these assumptions are avoided if one uses variational asymptotic method. VABS

  19. Duration of memory loss due to electron beam exposure. Final report Jan-May 1983

    SciTech Connect

    Wheeler, T.G.; Tilton, B.M.

    1983-08-01

    Electron beam exposure has been shown to produce retrograde amnesia (RA). The objective of this study was to determine the duration of memory loss upon electron beam exposure. It is important to know if exposure produces a memory loss of the events which occurred in the preceding 1 sec or memory loss of the preceding minute's events. The task was a single-trial avoidance paradigm. The animal was placed in a small aversive chamber. After a 90-sec adaptation period, a door opened that provided access to a large, dark, preferred chamber. The time required for the animal to enter the preferred chamber was the measure of interest (T). Once inside the preferred chamber, a 1-sec footshock was delivered. Following the footshock by some preset delay (delta T), the animal was exposed to a 10-microsec, 10-rad electron beam (or X-ray). A second trial on the task was run 2 hr postexposure. The second trial consisted of placing the animal in the aversive chamber and monitoring the time (T') required to enter the preferred chamber. If the electron beam exposure interfered with the animal's ability to recall the shock, T' would be greatly reduced as compared with the sham controls. The exposure delay times used were delta T = 1, 3, 5, and 10 sec.

  20. Loss of Energy Concentration in Nonlinear Evolution Beam Equations

    NASA Astrophysics Data System (ADS)

    Garrione, Maurizio; Gazzola, Filippo

    2017-05-01

    Motivated by the oscillations that were seen at the Tacoma Narrows Bridge, we introduce the notion of solutions with a prevailing mode for the nonlinear evolution beam equation u_{tt} + u_{xxxx} + f(u)= g(x, t) in bounded space-time intervals. We give a new definition of instability for these particular solutions, based on the loss of energy concentration on their prevailing mode. We distinguish between two different forms of energy transfer, one physiological (unavoidable and depending on the nonlinearity) and one due to the insurgence of instability. We then prove a theoretical result allowing to reduce the study of this kind of infinite-dimensional stability to that of a finite-dimensional approximation. With this background, we study the occurrence of instability for three different kinds of nonlinearities f and for some forcing terms g, highlighting some of their structural properties and performing some numerical simulations.

  1. Beam loss by collimation in a neutralizer duct

    SciTech Connect

    Hamilton, G.W.; Willmann, P.A.

    1980-04-03

    Beam fractions lost by collimation in a neutralizer duct are computed in x-x' phase space by using three examples of slab beam distributions under a broad range of duct dimensions, beam half-widths, and beam divergences. The results can be used to design compact neutralizers and to specify beam requirements. The computer code ILOST can be used under a broad range of beam conditions to compute the fraction lost by collimation.

  2. Comparative study of beam losses and heat loads reduction methods in MITICA beam source

    SciTech Connect

    Sartori, E. Agostinetti, P.; Dal Bello, S.; Marcuzzi, D.; Serianni, G.; Veltri, P.; Sonato, P.

    2014-02-15

    In negative ion electrostatic accelerators a considerable fraction of extracted ions is lost by collision processes causing efficiency loss and heat deposition over the components. Stripping is proportional to the local density of gas, which is steadily injected in the plasma source; its pumping from the extraction and acceleration stages is a key functionality for the prototype of the ITER Neutral Beam Injector, and it can be simulated with the 3D code AVOCADO. Different geometric solutions were tested aiming at the reduction of the gas density. The parameter space considered is limited by constraints given by optics, aiming, voltage holding, beam uniformity, and mechanical feasibility. The guidelines of the optimization process are presented together with the proposed solutions and the results of numerical simulations.

  3. Comparative study of beam losses and heat loads reduction methods in MITICA beam source

    NASA Astrophysics Data System (ADS)

    Sartori, E.; Agostinetti, P.; Dal Bello, S.; Marcuzzi, D.; Serianni, G.; Sonato, P.; Veltri, P.

    2014-02-01

    In negative ion electrostatic accelerators a considerable fraction of extracted ions is lost by collision processes causing efficiency loss and heat deposition over the components. Stripping is proportional to the local density of gas, which is steadily injected in the plasma source; its pumping from the extraction and acceleration stages is a key functionality for the prototype of the ITER Neutral Beam Injector, and it can be simulated with the 3D code AVOCADO. Different geometric solutions were tested aiming at the reduction of the gas density. The parameter space considered is limited by constraints given by optics, aiming, voltage holding, beam uniformity, and mechanical feasibility. The guidelines of the optimization process are presented together with the proposed solutions and the results of numerical simulations.

  4. Comparative study of beam losses and heat loads reduction methods in MITICA beam source.

    PubMed

    Sartori, E; Agostinetti, P; Dal Bello, S; Marcuzzi, D; Serianni, G; Sonato, P; Veltri, P

    2014-02-01

    In negative ion electrostatic accelerators a considerable fraction of extracted ions is lost by collision processes causing efficiency loss and heat deposition over the components. Stripping is proportional to the local density of gas, which is steadily injected in the plasma source; its pumping from the extraction and acceleration stages is a key functionality for the prototype of the ITER Neutral Beam Injector, and it can be simulated with the 3D code AVOCADO. Different geometric solutions were tested aiming at the reduction of the gas density. The parameter space considered is limited by constraints given by optics, aiming, voltage holding, beam uniformity, and mechanical feasibility. The guidelines of the optimization process are presented together with the proposed solutions and the results of numerical simulations.

  5. Measuring correlations between beam loss and residual radiation in the Fermilab Main Injector

    SciTech Connect

    Brown, Bruce C.; Wu, Guan Hong; /Fermilab

    2010-09-01

    In order to control beam loss for high intensity operation of the Fermilab Main Injector, electronics has been implemented to provide detailed loss measurements using gas-filled ionization monitors. Software to enhance routine operation and studies has been developed and losses are logged for each acceleration cycle. A systematic study of residual radiation at selected locations in the accelerator tunnel have been carried out by logging residual radiation at each of 142 bar-coded locations. We report on fits of the residual radiation measurements to half-life weighted sums of the beam loss data using a few characteristic lifetimes. The data are now available over a multi-year period including residual radiation measurements repeated multiple times during three extended facility shutdown periods. Measurement intervals of a few weeks combined with variable delays between beam off time and the residual measurement permits sensitivity to lifetimes from hours to years. The results allow planning for work in radiation areas to be based on calibrated analytic models.

  6. U. S. loss control management cuts production losses

    SciTech Connect

    Burger, J.R.

    1986-02-01

    Loss control, both as a phrase and a concept, isn't used very widely in the U.S. coal industry although a U.S. manufacturer has cut accidents 71% and increased productivity 40% using the system. Safety is a part of the loss control concept, but it goes beyond traditional accident and illness prevention to become management control of anything that can result in loss or property damage. This includes what ILCI calls incidents, that is, ''any undesired or unwanted event that could (or does) degrade the efficiency of the business operation.'' These incidents could be accidents, quality or production problems, or even security breaches (such as thefts). So while safety is always a basic element-loss control also includes absenteeism control, security, fire prevention and industrial hygiene, since they're all interrelated disciplines for reducing loss. A baseline evaluation is followed by recommendations and guidance in self-sustaining corrective measures. This program would cost about $3,500 the first year. Possibly this approach is not used in the U.S. because miners feel that with all the legislation and regulation of the industry no further program is needed.

  7. Aircraft Loss-of-Control Accident Analysis

    NASA Technical Reports Server (NTRS)

    Belcastro, Christine M.; Foster, John V.

    2010-01-01

    Loss of control remains one of the largest contributors to fatal aircraft accidents worldwide. Aircraft loss-of-control accidents are complex in that they can result from numerous causal and contributing factors acting alone or (more often) in combination. Hence, there is no single intervention strategy to prevent these accidents. To gain a better understanding into aircraft loss-of-control events and possible intervention strategies, this paper presents a detailed analysis of loss-of-control accident data (predominantly from Part 121), including worst case combinations of causal and contributing factors and their sequencing. Future potential risks are also considered.

  8. Automated beam steering using optimal control

    SciTech Connect

    Allen, C. K.

    2004-01-01

    We present a steering algorithm which, with the aid of a model, allows the user to specify beam behavior throughout a beamline, rather than just at specified beam position monitor (BPM) locations. The model is used primarily to compute the values of the beam phase vectors from BPM measurements, and to define cost functions that describe the steering objectives. The steering problem is formulated as constrained optimization problem; however, by applying optimal control theory we can reduce it to an unconstrained optimization whose dimension is the number of control signals.

  9. Flexible beam control using an adaptive truss

    NASA Technical Reports Server (NTRS)

    Warrington, Thomas J.; Horner, C. Garnett

    1990-01-01

    To demonstrate the feasibility of adaptive trusses for vibration suppression, a 12-ft-long beam is attached to a single cell of an adaptive truss which has three active battens. With the base of the adaptive truss attached to the laboratory frame, the measured strain of the vibrating beam shows the adaptive truss to be very effective in suppressing vibration when subjected to initial conditions. Control is accomplished by a PC/XT computer that implements an LQR-designed control law.

  10. Beam filling loss adjustments for ASR-9 weather channel reflectivity estimates

    NASA Astrophysics Data System (ADS)

    Engholm, Cynthia D.; Troxel, Seth W.

    1990-10-01

    The FAA is deploying over 100 new airport surveillance radars (ASR-9) across the country. In contrast to earlier ASRs, the ASR-9 utilizes a separate digital weather processing channel to provide air traffic controllers with timely, calibrated displays of precipitation intensity. The ASR-9 utilizes dual selectable fan shaped elevation beams designed to track aircraft over a large volume. As a consequence, weather echoes received from these fan shaped beams represent vertically averaged quantities. If the precipitation only partially or nonuniformly fills the beam, then the vertically integrated reflectivity may underestimate the actual intensity of the storm. The ASR-9 weather channel corrects for this by adjusting the range dependent six level reflectivity thresholds. The appropriateness of the currently implemented correction has not been carefully examined and may require modification to take into account regional and morphological variability in storm structure. The method used to derive new beam filling loss adjustments is discussed. An extensive database of volumetric pencil beam radar data were used in conjunction with the ASR-9 simulation facility to derive adjustments aimed at calibrating the precipitation intensity reports to the maximum perceived hazard. Results from this calibration indicate that a single correction is appropriate for all sites and intensities. The new corrections yield substantially improved results over the current corrections in producing these reflectivity reports.

  11. Rf beam control for the AGS Booster

    SciTech Connect

    Brennan, J.M.

    1994-09-26

    RF beam control systems for hadron synchrotrons have evolved over the past three decades into an essentially standard design. The key difference between hadron and lepton machines is the absence of radiation damping and existence of significant frequency variation in the case of hadrons. Although the motion of the hadron in the potential well of the rf wave is inherently stable it is not strongly damped. Damping must be provided by electronic feedback through the accelerating system. This feedback is typically called the phase loop. The technology of the rf beam control system for the AGS Booster synchrotron is described. First, the overall philosophy of the design is explained in terms of a conventional servo system that regulates the beam horizontal position in the vacuum chamber. The concept of beam transfer functions is fundamental to the mathematics of the design process and is reviewed. The beam transfer functions required for this design are derived from first principles. An overview of the beam signal pick-ups and high level rf equipment is given. The major subsystems, the frequency program, the heterodyne system, and beam feedback loops, are described in detail. Beyond accelerating the beam, the rf system must also synchronize the bunches in the Booster to the buckets in the AGS before transfer. The technical challenge in this process is heightened by the need to accomplish synchronization while the frequency is still changing. Details of the synchronization system are given. This report is intended to serve two purposes. One is to document the hardware and performance of the systems that have been built. The other is to serve as a tutorial vehicle from which the non-expert can not only learn the details of this system but also learn the principles of beam control that have led to the particular design choices made.

  12. Studies of Limits on Uncontrolled Heavy Ion Beam Losses for Allowing Hands-On Maintenance

    SciTech Connect

    Reginald M. Ronningen; Igor Remec

    2010-09-11

    Dose rates from accelerator components activated by 1 W/m beam losses are obtained semiempirically for a 1 GeV proton beam and by use of Monte Carlo transport codes for the proton beam and for 777 MeV/u 3He, 500 MeV/u 48Ca, 86Kr, 136Xe, and 400 MeV/u 238U ions. The dose rate obtained by the semi-empirical method, 0.99 mSv/h (99 mrem/h) at 30 cm, 4 h after 100 d irradiation by a 1-GeV proton beam, is consistent with studies at several accelerator facilities and with adopted hands-on maintenance dose rate limits. Monte Carlo simulations verify this result for protons and extend studies to heavy ion beam losses in drift-tube linac and superconducting linac accelerating structures. The studies indicate that the 1 W/m limit imposed on uncontrolled beam losses for high-energy proton beams might be relaxed for heavy ion beams. These studies further suggest that using the ratio of neutrons produced by a heavy ion beam to neutrons produced by a proton beam along with the dose rate from the proton beam (for thin-target scenarios) should allow an estimate of the dose rates expected from heavy ion beam losses.

  13. Control and manipulation of electron beams

    SciTech Connect

    Piot, Philippe; /NICADD, DeKalb /Northern Illinois U. /Fermilab

    2008-09-01

    The concepts of the advanced accelerators and light source rely on the production of bright electron beams. The rms areas of the beam phase space often need to be tailored to the specific applications. Furthermore, a new class of the forefront research calls for detailed specific distribution such as the particle density in the time coordinate. Several groups are tackling these various challenges and in this report we attempt to give a review of the state-of-the-art of the control and manipulation of the electron beams.

  14. Control and Manipulation of Electron Beams

    SciTech Connect

    Piot, Philippe

    2009-01-22

    The concepts of the advanced accelerators and light source rely on the production of bright electron beams. The rms areas of the beam phase space often need to be tailored to the specific applications. Furthermore, a new class of the forefront research calls for detailed specific distribution such as the particle density in the time coordinate. Several groups are tackling these various challenges and in this report we attempt to give a review of the state-of-the-art of the control and manipulation of the electron beams.

  15. Achievement of a low-loss 1-MW beam operation in the 3-GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex

    NASA Astrophysics Data System (ADS)

    Hotchi, H.; Harada, H.; Hayashi, N.; Kato, S.; Kinsho, M.; Okabe, K.; Saha, P. K.; Shobuda, Y.; Tamura, F.; Tani, N.; Watanabe, Y.; Yamamoto, K.; Yamamoto, M.; Yoshimoto, M.

    2017-06-01

    The 3-GeV rapid cycling synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC) is now in the final beam commissioning phase, aiming for a design output beam power of 1 MW. With a series of injector linac upgrades in 2013 and 2014, RCS developed a high-intensity beam test, and launched 1-MW beam tuning in October 2014. The most important issues in realizing such a high-power continuous beam operation are to control and minimize beam loss for maintaining machine activations within permissible levels. In RCS, numerical simulation was successfully utilized along with experimental approaches to isolate the mechanism of beam loss and find its solution. By iteratively performing actual beam experiments and numerical simulations, and also by several hardware improvements, we have recently established a 1-MW beam operation with very low fractional beam loss of a couple of 10-3 . In this paper, our recent efforts toward realizing such a low-loss high-intensity beam acceleration are presented as a follow-up of our previous article, H. Hotchi et al. Phys. Rev. ST Accel. Beams 12, 040402 (2009), 10.1103/PhysRevSTAB.12.040402, in which the initial beam commissioning status of RCS has been reported.

  16. Size modulated transition in the fluid–structure interaction losses in nano mechanical beam resonators

    SciTech Connect

    Vishwakarma, S. D.; Pratap, R.; Pandey, A. K.; Parpia, J. M.; Craighead, H. G.; Verbridge, S. S.

    2016-05-21

    An understanding of the dominant dissipative mechanisms is crucial for the design of a high-Q doubly clamped nanobeam resonator to be operated in air. We focus on quantifying analytically the viscous losses—the squeeze film damping and drag force damping—that limit the net quality factor of a beam resonator, vibrating in its flexural fundamental mode with the surrounding fluid as air at atmospheric pressure. Specifically, drag force damping dominates at smaller beam widths and squeeze film losses dominate at larger beam widths, with no significant contribution from structural losses and acoustic radiation losses. The combined viscous losses agree well with the experimentally measured Q of the resonator over a large range of beam widths, within the limits of thin beam theory. We propose an empirical relation between the maximum quality factor and the ratio of maximum beam width to the squeeze film air gap thickness.

  17. Size modulated transition in the fluid-structure interaction losses in nano mechanical beam resonators

    NASA Astrophysics Data System (ADS)

    Vishwakarma, S. D.; Pandey, A. K.; Parpia, J. M.; Verbridge, S. S.; Craighead, H. G.; Pratap, R.

    2016-05-01

    An understanding of the dominant dissipative mechanisms is crucial for the design of a high-Q doubly clamped nanobeam resonator to be operated in air. We focus on quantifying analytically the viscous losses—the squeeze film damping and drag force damping—that limit the net quality factor of a beam resonator, vibrating in its flexural fundamental mode with the surrounding fluid as air at atmospheric pressure. Specifically, drag force damping dominates at smaller beam widths and squeeze film losses dominate at larger beam widths, with no significant contribution from structural losses and acoustic radiation losses. The combined viscous losses agree well with the experimentally measured Q of the resonator over a large range of beam widths, within the limits of thin beam theory. We propose an empirical relation between the maximum quality factor and the ratio of maximum beam width to the squeeze film air gap thickness.

  18. Control of the formation of vortex Bessel beams in uniaxial crystals by varying the beam divergence

    SciTech Connect

    Paranin, V D; Karpeev, S V; Khonina, S N

    2016-02-28

    The transformation of zero-order Bessel beams into a second-order vortex Bessel beam in CaCO3 and LiNbO3 crystals is experimentally studied, and a possibility of controlling the beam transformation by changing the wavefront curvature of the illumi-nating beam is shown. A quasi-periodic nature of the Bessel beam transformation in a crystal while illuminating the diffraction axi-con by a convergent beam is observed (laser beams)

  19. SYNTHESIZER CONTROLLED BEAM TRANSFER FROM THE AGS TO RHIC.

    SciTech Connect

    DELONG,J.; BRENNAN,J.M.; FISCHER,W.; HAYES,T.; SMITH,K.; VALENTINO,S.

    2001-06-18

    To ensure minimal losses and to preserve longitudinal emittance, beam is transferred from the AGS to the RHIC bunch to bucket. This requires precision frequency and phase control for synchronization and kicker timing. The required precision is realized with a set of Direct Digital Synthesizers. Each synthesizer can be frequency and phase modulated to align the AGS bunch to the target bucket in the RHIC phase.

  20. A COMPACTRIO-BASED BEAM LOSS MONITOR FOR THE SNS RF TEST CAVE

    SciTech Connect

    Blokland, Willem; Armstrong, Gary A

    2009-01-01

    An RF Test Cave has been built at the Spallation Neutron Source (SNS) to be able to test RF cavities without interfering the SNS accelerator operations. In addition to using thick concrete wall to minimize radiation exposure, a Beam Loss Monitor (BLM) must abort the operation within 100 usec when the integrated radiation within the cave exceeds a threshold. We choose the CompactRIO platform to implement the BLM based on its performance, cost-effectiveness, and rapid development. Each in/output module is connected through an FPGA to provide point-by-point processing. Every 10 usec the data is acquired analyzed and compared to the threshold. Data from the FPGA is transferred using DMA to the real-time controller, which communicates to a gateway PC to talk to the SNS control system. The system includes diagnostics to test the hardware and integrates the losses in real-time. In this paper we describe our design, implementation, and results

  1. Particle Rate and Host Accelerator Beam Loss on the MICE Experiment

    SciTech Connect

    Dobbs, Adam James

    2011-10-01

    A study is presented of particle rates in the MICE Muon Beamline and their relationship to beam loss produced in ISIS. A brief overview of neutrino physics is presented, together with a discussion on the Neutrino Factory as a motivation for MICE. An overview of MICE itself is then presented, highlighting the need for a systematic understanding of the relationship between the MICE target parameters, ISIS beam loss, and MICE particle rate. The variation of beam loss with target depth is examined and observed to be non-linear. The variation of beam loss with respect to the target dip time in the ISIS cycle is examined and observed to be approximately linear for dip times between 11.1 ms and 12.6 ms after ISIS injection, before tailing at earlier dip times. The variation of beam loss with particle rate is also observed to follow an approximately linear relationship from 0.05 V.ms to 4.7 V.ms beam loss, with a further strong indication that this continues up to 7.1 V.ms. Particle identification using time-of-flight data is used to give an insight into the relative abundances of each particle species present in the MICE beam. Estimates of muon rate are then produced as a function of beam loss. At a level of 2 V.ms beam loss ~10.9 muons per spill for a 3.2 ms spill with negative π → μ optics, and ~31.1 muons per 1 ms spill with positive π → μ optics are observed. Simulations using the ORBIT particle tracking code of the beam loss distributions around the ISIS ring, caused by the MICE target, are also presented and the implications for MICE running discussed.

  2. Parametric Modeling of Electron Beam Loss in Synchrotron Light Sources

    SciTech Connect

    Sayyar-Rodsari, B.; Schweiger, C.; Hartman, E.; Corbett, J.; Lee, M.; Lui, P.; Paterson, E.; /SLAC

    2007-11-28

    Synchrotron light is used for a wide variety of scientific disciplines ranging from physical chemistry to molecular biology and industrial applications. As the electron beam circulates, random single-particle collisional processes lead to decay of the beam current in time. We report a simulation study in which a combined neural network (NN) and first-principles (FP) model is used to capture the decay in beam current due to Touschek, Bremsstrahlung, and Coulomb effects. The FP block in the combined model is a parametric description of the beam current decay where model parameters vary as a function of beam operating conditions (e.g. vertical scraper position, RF voltage, number of the bunches, and total beam current). The NN block provides the parameters of the FP model and is trained (through constrained nonlinear optimization) to capture the variation in model parameters as operating condition of the beam changes. Simulation results will be presented to demonstrate that the proposed combined framework accurately models beam decay as well as variation to model parameters without direct access to parameter values in the model.

  3. Collimation system design for beam loss localization with slipstacking injection in the Fermilab Main Injector

    SciTech Connect

    Drozhdin, A.I.; Brown, B.C.; Johnson, D.E.; Koba, K.; Kourbanis, I.; Mokhov, N.V.; Rakhno, I.L.; Sidorov, V.I.; /Fermilab

    2007-06-01

    Results of modeling with the 3-D STRUCT and MARS15 codes of beam loss localization and related radiation effects are presented for the slipstacking injection to the Fermilab Main Injector. Simulations of proton beam loss are done using multi-turn tracking with realistic accelerator apertures, nonlinear fields in the accelerator magnets and time function of the RF manipulations to explain the results of beam loss measurements. The collimation system consists of one primary and four secondary collimators. It intercepts a beam power of 1.6 kW at a scraping rate of 5% of 5.5E+13 ppp, with a beam loss rate in the ring outside the collimation region of 1 W/m or less. Based on thorough energy deposition and radiation modeling, a corresponding collimator design was developed that satisfies all the radiation and engineering constraints.

  4. Maritime Adaptive Optics Beam Control

    DTIC Science & Technology

    2010-09-01

    mantis shrimp for getting me through the home stretch. To all my advisors, mentors, friends, and family—you have my eternal gratitude for helping...the RLS algorithm does in fact converge faster than the LMS algorithm, yet at the same time the LMS algorithm can control significantly better during

  5. Beam loss studies in high-intensity heavy-ion linacs

    NASA Astrophysics Data System (ADS)

    Ostroumov, P. N.; Aseev, V. N.; Mustapha, B.

    2004-09-01

    The proposed Rare Isotope Accelerator (RIA) Facility, an innovative exotic-beam facility for the production of high-quality beams of short-lived isotopes, consists of a fully superconducting 1.4GV driver linac and a 140MV postaccelerator. To produce sufficient intensities of secondary beams the driver linac will provide 400kW primary beams of any ion from hydrogen to uranium. Because of the high intensity of the primary beams the beam losses must be minimized to avoid radioactivation of the accelerator equipment. To keep the power deposited by the particles lost on the accelerator structures below 1 W/m, the relative beam losses per unit length should be less than 10-5, especially along the high-energy section of the linac. A new beam dynamics simulation code TRACK has been developed and used for beam loss studies in the RIA driver linac. In the TRACK code, ions are tracked through the three-dimensional electromagnetic fields of every element of the linac starting from the electron cyclotron resonance (ECR) ion source to the production target. The simulation starts with a multicomponent dc ion beam extracted from the ECR. The space charge forces are included in the simulations. They are especially important in the front end of the driver linac. Beam losses are studied by tracking a large number of particles (up to 106) through the whole linac considering all sources of error such us element misalignments, rf field errors, and stripper thickness fluctuations. For each configuration of the linac, multiple sets of error values have been randomly generated and used in the calculations. The results are then combined to calculate important beam parameters, estimate beam losses, and characterize the corresponding linac configuration. To track a large number of particles for a comprehensive number of error sets (up to 500), the code TRACK was parallelized and run on the Jazz computer cluster at ANL.

  6. Active control of buckling of flexible beams

    NASA Technical Reports Server (NTRS)

    Baz, A.; Tampe, L.

    1989-01-01

    Mathematical models are presented that simulate the dynamic characteristics of shape memory alloy actuators made of nickel-titanium alloy (Nitinol) controlling the buckling of compressive structural members. A closed-loop computer-controlled system has been designed, based on the proposed mathematical models, and has been implemented to control the buckling of simple beams. The performance of the computer-controlled system is evaluated experimentally and compared with the theoretical predictions to validate the developed models. The results emphasized the importance of buckling control and suggest the potential of shape memory alloy actuators as attractive means for controlling structural deformation in a simple and reliable way.

  7. Statistical process control for electron beam monitoring.

    PubMed

    López-Tarjuelo, Juan; Luquero-Llopis, Naika; García-Mollá, Rafael; Quirós-Higueras, Juan David; Bouché-Babiloni, Ana; Juan-Senabre, Xavier Jordi; de Marco-Blancas, Noelia; Ferrer-Albiach, Carlos; Santos-Serra, Agustín

    2015-07-01

    To assess the electron beam monitoring statistical process control (SPC) in linear accelerator (linac) daily quality control. We present a long-term record of our measurements and evaluate which SPC-led conditions are feasible for maintaining control. We retrieved our linac beam calibration, symmetry, and flatness daily records for all electron beam energies from January 2008 to December 2013, and retrospectively studied how SPC could have been applied and which of its features could be used in the future. A set of adjustment interventions designed to maintain these parameters under control was also simulated. All phase I data was under control. The dose plots were characterized by rising trends followed by steep drops caused by our attempts to re-center the linac beam calibration. Where flatness and symmetry trends were detected they were less-well defined. The process capability ratios ranged from 1.6 to 9.3 at a 2% specification level. Simulated interventions ranged from 2% to 34% of the total number of measurement sessions. We also noted that if prospective SPC had been applied it would have met quality control specifications. SPC can be used to assess the inherent variability of our electron beam monitoring system. It can also indicate whether a process is capable of maintaining electron parameters under control with respect to established specifications by using a daily checking device, but this is not practical unless a method to establish direct feedback from the device to the linac can be devised. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  8. Controlling Second Harmonic Efficiency of Laser Beam Interactions

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  9. Beam current controller for laser ion source

    DOEpatents

    Okamura, Masahiro

    2014-10-28

    The present invention relates to the design and use of an ion source with a rapid beam current controller for experimental and medicinal purposes. More particularly, the present invention relates to the design and use of a laser ion source with a magnetic field applied to confine a plasma flux caused by laser ablation.

  10. Beam loss and backgrounds in the CDF and D0 detectors due to nuclear elastic beam-gas scattering

    SciTech Connect

    Alexandr I. Drozhdin; Valery A. Lebedev; Nikolai V. Mokhov

    2003-05-27

    Detailed simulations were performed on beam loss rates in the vicinity of the Tevatron Collider detectors due to beam-gas nuclear elastic interactions. It turns out that this component can drive the accelerator-related background rates in the CDF and D0 detectors, exceeding those due to outscattering from collimation system, inelastic beam-gas interactions and other processes [1, 2]. Results of realistic simulations with the STRUCT and MARS codes are presented for the interaction region components and the CDF and D0 detectors. It is shown that a steel mask placed upstream of the detectors can reduce the background rates by almost an order of magnitude.

  11. Development of wide dynamic range beam loss monitor system for J-PARC main ring

    NASA Astrophysics Data System (ADS)

    Satou, K.; Toyama, T.; Kamikubota, N.; Yamada, S.; Yoshida, S.

    2017-07-01

    The new beam loss monitor (BLM) system now in operation at the main ring of J- PARC consists of an isolated front-end current to voltage converter, a VME-based 24 bit ADC system. A dual detector system employs a proportional-type gas chamber (PBLM) and an air- filled ionization chamber (AIC). The system shows a wide dynamic range of 160 dB. It can detect the low level signal that would arise in the case of the detection of residual dose in the ring itself after the beam has been turned off as well as an event such as high level beam loss at the collimators. The signal rise time of the waveform obtained is 17 µs which is fast enough to meet the speed requirement of the Machine Protection System (MPS); which is that the MPS should dump the beam within 100 µs when the beam loss signal exceeds the reference levels set in the ADC system.

  12. Electron beam guiding by grooved SiO{sub 2} parallel plates without energy loss

    SciTech Connect

    Xue, Yingli; Yu, Deyang Liu, Junliang; Zhang, Mingwu; Yang, Bian; Zhang, Yuezhao; Cai, Xiaohong

    2015-12-21

    Using a pair of grooved SiO{sub 2} parallel plates, stably guided electron beams were obtained without energy loss at 800–2000 eV. This shows that the transmitted electrons are guided by a self-organized repulsive electric field, paving the way for a self-adaptive manipulation of electron beams.

  13. Method and apparatus for laser-controlled proton beam radiology

    DOEpatents

    Johnstone, C.J.

    1998-06-02

    A proton beam radiology system provides cancer treatment and proton radiography. The system includes an accelerator for producing an H{sup {minus}} beam and a laser source for generating a laser beam. A photodetachment module is located proximate the periphery of the accelerator. The photodetachment module combines the H{sup {minus}} beam and laser beam to produce a neutral beam therefrom within a subsection of the H{sup {minus}} beam. The photodetachment module emits the neutral beam along a trajectory defined by the laser beam. The photodetachment module includes a stripping foil which forms a proton beam from the neutral beam. The proton beam is delivered to a conveyance segment which transports the proton beam to a patient treatment station. The photodetachment module further includes a laser scanner which moves the laser beam along a path transverse to the cross-section of the H{sup {minus}} beam in order to form the neutral beam in subsections of the H{sup {minus}} beam. As the scanning laser moves across the H{sup {minus}} beam, it similarly varies the trajectory of the proton beam emitted from the photodetachment module and in turn varies the target location of the proton beam upon the patient. Intensity modulation of the proton beam can also be achieved by controlling the output of the laser. 9 figs.

  14. Method and apparatus for laser-controlled proton beam radiology

    DOEpatents

    Johnstone, Carol J.

    1998-01-01

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

  15. Use of beam deflection to control an electron beam wire deposition process

    NASA Technical Reports Server (NTRS)

    Taminger, Karen M. (Inventor); Hofmeister, William H. (Inventor); Hafley, Robert A. (Inventor)

    2013-01-01

    A method for controlling an electron beam process wherein a wire is melted and deposited on a substrate as a molten pool comprises generating the electron beam with a complex raster pattern, and directing the beam onto an outer surface of the wire to thereby control a location of the wire with respect to the molten pool. Directing the beam selectively heats the outer surface of the wire and maintains the position of the wire with respect to the molten pool. An apparatus for controlling an electron beam process includes a beam gun adapted for generating the electron beam, and a controller adapted for providing the electron beam with a complex raster pattern and for directing the electron beam onto an outer surface of the wire to control a location of the wire with respect to the molten pool.

  16. Energy spectrum control for modulated proton beams

    SciTech Connect

    Hsi, Wen C.; Moyers, Michael F.; Nichiporov, Dmitri; Anferov, Vladimir; Wolanski, Mark; Allgower, Chris E.; Farr, Jonathan B.; Mascia, Anthony E.; Schreuder, Andries N.

    2009-06-15

    In proton therapy delivered with range modulated beams, the energy spectrum of protons entering the delivery nozzle can affect the dose uniformity within the target region and the dose gradient around its periphery. For a cyclotron with a fixed extraction energy, a rangeshifter is used to change the energy but this produces increasing energy spreads for decreasing energies. This study investigated the magnitude of the effects of different energy spreads on dose uniformity and distal edge dose gradient and determined the limits for controlling the incident spectrum. A multilayer Faraday cup (MLFC) was calibrated against depth dose curves measured in water for nonmodulated beams with various incident spectra. Depth dose curves were measured in a water phantom and in a multilayer ionization chamber detector for modulated beams using different incident energy spreads. Some nozzle entrance energy spectra can produce unacceptable dose nonuniformities of up to {+-}21% over the modulated region. For modulated beams and small beam ranges, the width of the distal penumbra can vary by a factor of 2.5. When the energy spread was controlled within the defined limits, the dose nonuniformity was less than {+-}3%. To facilitate understanding of the results, the data were compared to the measured and Monte Carlo calculated data from a variable extraction energy synchrotron which has a narrow spectrum for all energies. Dose uniformity is only maintained within prescription limits when the energy spread is controlled. At low energies, a large spread can be beneficial for extending the energy range at which a single range modulator device can be used. An MLFC can be used as part of a feedback to provide specified energy spreads for different energies.

  17. Energy spectrum control for modulated proton beams

    PubMed Central

    Hsi, Wen C.; Moyers, Michael F.; Nichiporov, Dmitri; Anferov, Vladimir; Wolanski, Mark; Allgower, Chris E.; Farr, Jonathan B.; Mascia, Anthony E.; Schreuder, Andries N.

    2009-01-01

    In proton therapy delivered with range modulated beams, the energy spectrum of protons entering the delivery nozzle can affect the dose uniformity within the target region and the dose gradient around its periphery. For a cyclotron with a fixed extraction energy, a rangeshifter is used to change the energy but this produces increasing energy spreads for decreasing energies. This study investigated the magnitude of the effects of different energy spreads on dose uniformity and distal edge dose gradient and determined the limits for controlling the incident spectrum. A multilayer Faraday cup (MLFC) was calibrated against depth dose curves measured in water for nonmodulated beams with various incident spectra. Depth dose curves were measured in a water phantom and in a multilayer ionization chamber detector for modulated beams using different incident energy spreads. Some nozzle entrance energy spectra can produce unacceptable dose nonuniformities of up to ±21% over the modulated region. For modulated beams and small beam ranges, the width of the distal penumbra can vary by a factor of 2.5. When the energy spread was controlled within the defined limits, the dose nonuniformity was less than ±3%. To facilitate understanding of the results, the data were compared to the measured and Monte Carlo calculated data from a variable extraction energy synchrotron which has a narrow spectrum for all energies. Dose uniformity is only maintained within prescription limits when the energy spread is controlled. At low energies, a large spread can be beneficial for extending the energy range at which a single range modulator device can be used. An MLFC can be used as part of a feedback to provide specified energy spreads for different energies. PMID:19610318

  18. RESULTS OF BACKGROUND SUBTRACTION TECHNIQUES ON THE SPALLATION NEUTRON SOURCE BEAM LOSS MONITORS

    SciTech Connect

    Pogge, James R; Zhukov, Alexander P

    2010-01-01

    Recent improvements to the Spallation Neutron Source (SNS) beam loss monitor (BLM) designs have been made with the goal of significantly reducing background noise. This paper outlines this effort and analyzes the results. The significance of this noise reduction is the ability to use the BLM sensors [1], [2], [3] distributed throughout the SNS accelerator as a method to monitor activation of components as well as monitor beam losses.

  19. Modal control of beam flexural vibration

    PubMed

    Rizet; Brissaud; Gonnard; Bera; Sunyach

    2000-04-01

    An active control system was developed to control the flexural vibrations of a beam with a modal filtering with only one secondary actuator. Segmented piezoelectric actuators and sensors were used for driving and sensing the bending beam vibrations. The primary actuator was fed by a broadband random disturbance signal in order to excite the first five modes of the structure. However, only the second to fifth modes were controlled. The control algorithm was implemented on a DSP board and the input and output signals were filtered using high order low pass filters. These filters, implemented on the DSP board avoid the degrading effect on the control performances of the higher order modes and which are not controlled. The modal filtering was achieved by computing. To this end, it is based on a previous identification procedure. This latter models, in one step, the dynamics of the structure and also the transfer function of the electronic circuits of the controller. The identified filtered modes were then used to compute the gain matrix using a LQR technique (linear quadratic regulator). Simulations of the active control were carried out and practical implementation of the control algorithms was performed. Experimental and simulation results were then compared and discussed.

  20. PRELIMINARY DESIGN OF THE BEAM LOSS MONITORING SYSTEM FOR THE SNS.

    SciTech Connect

    WITKOVER,R.; GASSNER,D.

    2002-05-06

    The SNS to be built at Oak Ridge National Laboratory will provide a high average intensity 1 GeV beam to produce spallation neutrons. Loss of a even small percentage of this intense beam would result in high radiation. The Beam Loss Monitor (ELM) system must detect such small, long term losses yet be capable of measuring infrequent short high losses. The large dynamic range presents special problems for the system design. Ion chambers will be used as the detectors. A detector originally designed for the FNAL Tevatron, was considered but concerns about ion collection times and low collection efficiency at high loss rates favor a new design. The requirements and design concepts of the proposed approach will be presented. Discussion of the design and testing of the ion chambers and the analog j-Point end electronics will be presented. The overall system design will be described.

  1. Active control of flexural vibrations in beams

    NASA Technical Reports Server (NTRS)

    Gerhold, Carl H.; Rocha, Rodney

    1989-01-01

    An analytical model of the feedback control system which estimates the voltage generated by the piezoelectric sensor as a function of the dynamic stress at the sensor location and the force exerted by the driver piezoelectric as a function of signal gain is developed. The analytical results are compared to measured results for a cantilever beam excited to vibrate in its first natural mode. The estimated increase in the first mode damping factor is in good agreement with the measured results.

  2. Beam losses due to abrupt crab cavity failures in the LHC

    SciTech Connect

    Baer, T.; Barranco, J.; Calaga, R.; Tomas, R.; Wenninger, B.; Yee, B.; Zimmermann, F.

    2011-03-28

    A major concern for the implementation of crab crossing in a future High-Luminosity LHC (HL-LHC) is machine protection in an event of a fast crab-cavity failure. Certain types of abrupt crab-cavity amplitude and phase changes are simulated to characterize the effect of failures on the beam and the resulting particle-loss signatures. The time-dependent beam loss distributions around the ring and particle trajectories obtained from the simulations allow for a first assessment of the resulting beam impact on LHC collimators and on sensitive components around the ring. Results for the nominal LHC lattice is presented.

  3. Beam loss and collimation in the Fermilab 16 GeV proton driver

    SciTech Connect

    Alexandr I. Drozhdin, Oleg E. Krivosheev and Nikolai V. Mokhov

    2001-07-20

    A high beam power of 1.15 MW in the proposed 16-GeV Proton Driver [1] implies serious constraints on beam losses in the machine. The main concerns are the hands-on maintenance and ground-water activation. Only with a very efficient beam collimation system can one reduce uncontrolled beam losses to an allowable level. The results on tolerable beam loss and on a proposed beam collimation system are summarized in this paper. A multi-turn particle tracking in the accelerator defined by all lattice components with their realistic strengths and aperture restrictions, and halo interactions with the collimators is done with the STRUCT code [2]. Full-scale Monte Carlo hadronic and electromagnetic shower simulations in the lattice elements, shielding, tunnel and surrounding dirt with realistic geometry, materials and magnetic field are done with the MARS14 code [3]. It is shown that the proposed 3-stage collimation system, allows localization of more than 99% of beamloss in a special straight section. Beam loss in the rest of the accelerator is 0.2 W/m on average.

  4. H- Beam Loss and Evidence for Intrabeam Stripping in the LANSCE Linac

    SciTech Connect

    Rybarcyk, Lawrence J.; Kelsey, Charles T. IV; McCrady, Rodney C.; Pang, Xiaoying

    2012-05-15

    The LANSCE accelerator complex is a multi-beam, multi-user facility that provides high-intensity H{sup +} and H{sup -} particle beams for a variety of user programs. At the heart of the facility is a room temperature linac that is comprised of 100-MeV drift tube and 800-MeV coupled cavity linac (CCL) structures. Although both beams are similar in intensity and emittance at 100 MeV, the beam-loss monitors along the CCL show a trend of increased loss for H{sup -} that is not present for H{sup +}. This difference is attributed to stripping mechanisms that affect H{sup -} and not H{sup +}. We present the results of an analysis of H{sup -} beam loss along the CCL that incorporates beam spill measurements, beam dynamics simulations, analytical models and radiation transport estimates using the MCNPX code. The results indicate a significant fraction of these additional losses result from intrabeam stripping.

  5. The upgraded data acquisition system for beam loss monitoring at the Fermilab Tevatron and Main Injector

    NASA Astrophysics Data System (ADS)

    Baumbaugh, A.; Briegel, C.; Brown, B. C.; Capista, D.; Drennan, C.; Fellenz, B.; Knickerbocker, K.; Lewis, J. D.; Marchionni, A.; Needles, C.; Olson, M.; Pordes, S.; Shi, Z.; Still, D.; Thurman-Keup, R.; Utes, M.; Wu, J.

    2011-11-01

    A VME-based data acquisition system for beam-loss monitors has been developed and is in use in the Tevatron and Main Injector accelerators at the Fermilab complex. The need for enhanced beam-loss protection when the Tevatron is operating in collider-mode was the main driving force for the new design. Prior to the implementation of the present system, the beam-loss monitor system was disabled during collider operation and protection of the Tevatron magnets relied on the quench protection system. The new Beam-Loss Monitor system allows appropriate abort logic and thresholds to be set over the full set of collider operating conditions. The system also records a history of beam-loss data prior to a beam-abort event for post-abort analysis. Installation of the Main Injector system occurred in the fall of 2006 and the Tevatron system in the summer of 2007. Both systems were fully operation by the summer of 2008. In this paper we report on the overall system design, provide a description of its normal operation, and show a number of examples of its use in both the Main Injector and Tevatron.

  6. Reliability of Beam Loss Monitor Systems for the Large Hadron Collider

    SciTech Connect

    Guaglio, G.; Dehning, B.; Santoni, C.

    2005-06-08

    The increase of beam energy and beam intensity, together with the use of super conducting magnets, opens new failure scenarios and brings new criticalities for the whole accelerator protection system. For the LHC beam loss protection system, the failure rate and the availability requirements have been evaluated using the Safety Integrity Level (SIL) approach. A downtime cost evaluation is used as input for the SIL approach. The most critical systems, which contribute to the final SIL value, are the dump system, the interlock system, the beam loss monitors system, and the energy monitor system. The Beam Loss Monitors System (BLMS) is critical for short and intense particles losses at 7 TeV and assisted by the Fast Beam Current Decay Monitors at 450 GeV. At medium and higher loss time it is assisted by other systems, such as the quench protection system and the cryogenic system. For BLMS, hardware and software have been evaluated in detail. The reliability input figures have been collected using historical data from the SPS, using temperature and radiation damage experimental data as well as using standard databases. All the data has been processed by reliability software (Isograph). The analysis spaces from the components data to the system configuration.

  7. Stochastic Orbit Loss of Neutral Beam Ions From NSTX Due to Toroidal Alfven Eigenmode Avalanches

    SciTech Connect

    Darrow, D S; Fredrickson, E D; Gorelenkov, N N; Gorelenkova, M; Kubota, S; Medley, S S; Podesta, M; Shi, L

    2012-07-11

    Short toroidal Alfven eigenmode (TAE) avalanche bursts in the National Spherical Torus Experiment (NSTX) cause a drop in the neutron rate and sometimes a loss of neutral beam ions at or near the full injection energy over an extended range of pitch angles. The simultaneous loss of wide ranges of pitch angle suggests stochastic transport of the beam ions occurs. When beam ion orbits are followed with a guiding center code that incorporates plasma's magnetic equilibrium plus the measured modes, the predicted ranges of lost pitch angle are similar to those seen in the experiment, with distinct populations of trapped and passing orbits lost. These correspond to domains where the stochasticity extends in the orbit phase space from the region of beam ion deposition to the loss boundary.

  8. Consideration of neutral beam prompt loss in the design of a tokamak helicon antenna

    SciTech Connect

    Pace, D. C.; Van Zeeland, M. A.; Fishler, B.; Murphy, C.

    2016-08-02

    Neutral beam prompt losses (injected neutrals that ionize such that their first poloidal transit intersects with the wall) can put appreciable power on the outer wall of tokamaks, and this power may damage the wall or other internal components. These prompt losses are simulated including a protruding helicon antenna installation in the DIII-D tokamak and it is determined that 160 kW of power will impact the antenna during the injection of a particular neutral beam. Protective graphite tiles are designed in response to this modeling and the wall shape of the installed antenna is precisely measured to improve the accuracy of these calculations. Initial experiments con rm that the antenna component temperature increases according to the amount of neutral beam energy injected into the plasma. Incorporating neutral beam prompt loss considerations into the design of this in-vessel component serves to ensure that adequate protection or cooling is provided.

  9. Consideration of neutral beam prompt loss in the design of a tokamak helicon antenna

    DOE PAGES

    Pace, D. C.; Van Zeeland, M. A.; Fishler, B.; ...

    2016-08-02

    Neutral beam prompt losses (injected neutrals that ionize such that their first poloidal transit intersects with the wall) can put appreciable power on the outer wall of tokamaks, and this power may damage the wall or other internal components. These prompt losses are simulated including a protruding helicon antenna installation in the DIII-D tokamak and it is determined that 160 kW of power will impact the antenna during the injection of a particular neutral beam. Protective graphite tiles are designed in response to this modeling and the wall shape of the installed antenna is precisely measured to improve the accuracymore » of these calculations. Initial experiments con rm that the antenna component temperature increases according to the amount of neutral beam energy injected into the plasma. Incorporating neutral beam prompt loss considerations into the design of this in-vessel component serves to ensure that adequate protection or cooling is provided.« less

  10. Combined dispersant fluid loss control additives

    SciTech Connect

    Villa, J. L.; Zeiner, R. N.

    1985-12-31

    Water soluble polymer compositions containing polyacrylic acid and copolymer of itaconic acid and acrylamide are useful as combined dispersant and fluid loss control additives for aqueous drilling fluids, particularly fresh water, gypsum and seawater muds. An example is a polymer composition containing about 80% by weight polyacrylic acid and about 20% by weight copolymer of itaconic acid and acrylamide in its ammonium salt form.

  11. Fluid loss control in well cement slurries

    SciTech Connect

    Roark, D.N.; Nugent, A.; Bandlish, B.K.

    1987-04-14

    This patent describes a fluid-loss-control additive adapted for use in cementing subterranean well formations with an aqueous well cement slurry. The additive comprises in combination, an anydrous mixture of (i) a lignosulfonate polymer or a condensed naphthalene sulfonate polymer or a sulfonated vinylaromatic polymer or any combination thereof and (ii) an unmodified or a chemically modified polymer of monoallylamine.

  12. Active control of flexural vibrations in beams

    NASA Technical Reports Server (NTRS)

    Gerhold, Carl H.

    1987-01-01

    The feasibility of using piezoelectric actuators to control the flexural oscillations of large structures in space is investigated. Flexural oscillations are excited by impulsive loads. The vibratory response can degrade the pointing accuracy of cameras and antennae, and can cause high stresses at structural node points. Piezoelectric actuators have the advantage of exerting localized bending moments. In this way, vibration is controlled without exciting rigid body modes. The actuators are used in collocated sensor/driver pairs to form a feedback control system. The sensor produces a voltage that is proportional to the dynamic stress at the sensor location, and the driver produces a force that is proportional to the voltage applied to it. The analog control system amplifies and phase shifts the sensor signal to produce the voltage signal that is applied to the driver. The feedback control is demonstrated to increase the first mode damping in a cantilever beam by up to 100 percent, depending on the amplifier gain. The damping efficiency of the control system when the piezoelectrics are not optimally positioned at points of high stress in the beam is evaluated.

  13. Digital Controller For Laser-Beam-Steering Subsystem: Part 2

    NASA Technical Reports Server (NTRS)

    Ansari, Homayoon; Voisinet, Leeann

    1995-01-01

    A report presents additional information about laser-beam-steering apparatus described in "Digital Controller for Laser-Beam-Steering Subsystem" (NPO-19193) and "More About Beam-Steering Subsystem for Laser Communication" (NPO-19381). Reiterates basic principles of operation of beam-steering subsystem, with emphasis on modes of operation, basic design concepts, and initial experiments on partial prototype of apparatus.

  14. Exact Controllability and Perturbation Analysis for Elastic Beams

    SciTech Connect

    Moreles, Miguel Angel

    2004-05-15

    The Rayleigh beam is a perturbation of the Bernoulli-Euler beam. We establish convergence of the solution of the Exact Controllability Problem for the Rayleigh beam to the corresponding solution of the Bernoulli-Euler beam. Convergence is related to a Singular Perturbation Problem. The main tool in solving this perturbation problem is a weak version of a lower bound for hyperbolic polynomials.

  15. Digital Controller For Laser-Beam-Steering Subsystem: Part 2

    NASA Technical Reports Server (NTRS)

    Ansari, Homayoon; Voisinet, Leeann

    1995-01-01

    A report presents additional information about laser-beam-steering apparatus described in "Digital Controller for Laser-Beam-Steering Subsystem" (NPO-19193) and "More About Beam-Steering Subsystem for Laser Communication" (NPO-19381). Reiterates basic principles of operation of beam-steering subsystem, with emphasis on modes of operation, basic design concepts, and initial experiments on partial prototype of apparatus.

  16. GGOT total pressure loss control concept evaluation

    NASA Technical Reports Server (NTRS)

    Blumenthal, R. F.

    1993-01-01

    Total pressure loss is one of the most important parameters in the design of a turbine. This parameter effects not only the turbine performance, but consequently the engine power balance and engine performance. Computational Fluid Dynamics (CFD) can be an effective tool in predicting turbine total pressure loss, and also for performing sensitivity studies to achieve an optimal design with respect to pressure loss. In the present study, the AEROVISC code was used to predict the total pressure loss in the Turbine Technology Team Gas Generator Oxidizer Turbine (GGOT). The objectives in this study are two-fold. It is first necessary to determine an optimal methodology in predicting total pressure loss. The type of grid, grid density and distribution are parameters which may affect the loss prediction. Also, the effect of using a standard K-epsilon turbulence model with wall functions versus a two-layer turbulence model needs to be investigated. The use of grid embedding to resolve areas with high flow gradients needs to be explored. The second objective of the study is to apply the optimal methodology toward evaluating different tip leakage control concepts.

  17. Beam Loss due to Foil Scattering in the SNS Accumulator Ring

    SciTech Connect

    Holmes, Jeffrey A; Plum, Michael A

    2012-01-01

    In order to better understand the contribution of scattering from the primary stripper foil to losses in the SNS ring, we have carried out calculations using the ORBIT Code aimed at evaluating these losses. These calculations indicate that the probability of beam loss within one turn following a foil hit is ~1.8 10-8 , where is the foil thickness in g/cm2, assuming a carbon foil. Thus, for a typical SNS stripper foil of thickness = 390 g/cm2, the probability of loss within one turn of a foil hit is ~7.0 10-6. This note describes the calculations used to arrive at this result, presents the distribution of these losses around the SNS ring, and compares the calculated results with observed ring losses for a well-tuned production beam.

  18. An approach to fundamental study of beam loss minimization

    SciTech Connect

    Jameson, R.A. )

    1999-06-01

    The accelerator design rules involving rms matching, developed at CERN in the 1970[close quote]s, are discussed. An additional rule, for equipartitioning the beam energy among its degrees of freedom, may be added to insure an rms equilibrium condition. If the strong stochasticity threshold is avoided, as it is in realistic accelerator designs, the dynamics is characterized by extremely long transient settling times, making the role of equipartitioning hard to explain. An approach to systematic study using the RFQ accelerator as a simulation testbed is discussed. New methods are available from recent advances in research on complexity, nonlinear dynamics, and chaos. [copyright] [ital 1999 American Institute of Physics.

  19. Calculating the Loss factor of the LCLS Beam Line Elements for Ultra-Shrot Bunches

    SciTech Connect

    Novokhatski, A.; /SLAC

    2009-10-17

    The Linac Coherent Light Source (LCLS) is a SASE 1.5-15 {angstrom} x-ray Free-Electron Laser (FEL) facility. Since an ultra-short intense bunch is used in the LCLS operation one might suggest that wake fields, generated in the vacuum chamber, may have an effect on the x-ray production because these fields can change the beam particle energies thereby increasing the energy spread in a bunch. At LCLS a feedback system precisely controls the bunch energy before it enters a beam transport line after the linac. However, in the transport line and later in the undulator section the bunch energy and energy spread are not under feedback control and may change due to wake field radiation, which depends upon the bunch current or on a bunch length. The linear part of the energy spread can be compensated in the upstream linac; the energy loss in the undulator section can be compensated by varying the K-parameter of the undulators, however we need a precise knowledge of the wake fields in this part of the machine. Resistive wake fields are known and well calculated. We discuss an additional part of the wake fields, which comes from the different vacuum elements like bellows, BPMs, transitions, vacuum ports, vacuum valves and others. We use the code 'NOVO' together with analytical estimations for the wake potential calculations.

  20. Location of Maximum Credible Beam Losses in LCLS Injector

    SciTech Connect

    Mao, Stan

    2010-12-13

    The memo describes the maximum credible beam the LCLS injector can produce and lose at various locations along the beamline. The estimation procedure is based upon three previous reports [1, 2, 3]. While specific numbers have been updated to accurately reflect the present design parameters, the conclusions are very similar to those given in Ref 1. The source of the maximum credible beam results from the explosive electron emission from the photocathode if the drive laser intensity exceeds the threshold for plasma production. In this event, the gun's RF field can extract a large number of electrons from this plasma which are accelerated out of the gun and into the beamline. This electron emission persists until it has depleted the gun of all its energy. Hence the number of electrons emitted per pulse is limited by the amount of stored RF energy in the gun. It needs to be emphasized that this type of emission is highly undesirable, as it causes permanent damage to the cathode.

  1. Effects of Optical Loss Factors on Heliostat Field Layout for Beam-Down Solar Concentrating Systems

    NASA Astrophysics Data System (ADS)

    Utamura, Motoaki; Takamatsu, Tadahiko; Yuasa, Minoru; Kajita, Rina; Yamamoto, Takashi

    A methodology to give an optimal layout of a group of heliostats has been developed for beam-down concentrating solar tower systems. Given the maximum solar power together with optical parameters, the method determines an optimal configuration of a heliostat field around a tower. Various optical losses such as cosine factor, shadowing and blocking at heliostats are considered in the calculation. Furthermore, spillage at the receiver is taken into account due to the spread of light caused by the effects of a finite solar disk, flat facet and various stochastic errors in optical hardware and control. It is found the effect of spillage becomes significant at heliostats from the tower at the distance farther than four times of upper focus height of the reflector when receiver diameter is one fifteenth of the height and dominates the configuration of the optimal heliostat layout.

  2. Shielding NSLS-II light source: Importance of geometry for calculating radiation levels from beam losses

    NASA Astrophysics Data System (ADS)

    Kramer, S. L.; Ghosh, V. J.; Breitfeller, M.; Wahl, W.

    2016-11-01

    Third generation high brightness light sources are designed to have low emittance and high current beams, which contribute to higher beam loss rates that will be compensated by Top-Off injection. Shielding for these higher loss rates will be critical to protect the projected higher occupancy factors for the users. Top-Off injection requires a full energy injector, which will demand greater consideration of the potential abnormal beam miss-steering and localized losses that could occur. The high energy electron injection beam produces significantly higher neutron component dose to the experimental floor than a lower energy beam injection and ramped operations. Minimizing this dose will require adequate knowledge of where the miss-steered beam can occur and sufficient EM shielding close to the loss point, in order to attenuate the energy of the particles in the EM shower below the neutron production threshold (<10 MeV), which will spread the incident energy on the bulk shield walls and thereby the dose penetrating the shield walls. Designing supplemental shielding near the loss point using the analytic shielding model is shown to be inadequate because of its lack of geometry specification for the EM shower process. To predict the dose rates outside the tunnel requires detailed description of the geometry and materials that the beam losses will encounter inside the tunnel. Modern radiation shielding Monte-Carlo codes, like FLUKA, can handle this geometric description of the radiation transport process in sufficient detail, allowing accurate predictions of the dose rates expected and the ability to show weaknesses in the design before a high radiation incident occurs. The effort required to adequately define the accelerator geometry for these codes has been greatly reduced with the implementation of the graphical interface of FLAIR to FLUKA. This made the effective shielding process for NSLS-II quite accurate and reliable. The principles used to provide supplemental

  3. Water Loss Control for Military Installations

    DTIC Science & Technology

    2011-05-12

    US Army Corps of Engineers BUILDING STRONG® Water Loss Control for Military Installations Richard J. Scholze US Army ERDC-CERL, Champaign, IL...THIS PAGE unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 BUILDING STRONG® BUILDING STRONG® BUILDING STRONG® Background...economic and environmental concerns  Preventive maintenance ► Water systems underground, out of sight, out of mind BUILDING STRONG® True Cost of

  4. The role of electronic energy loss in ion beam modification of materials

    DOE PAGES

    Weber, William J.; Duffy, Dorothy M.; Thome, Lionel; ...

    2014-10-05

    The interaction of energetic ions with solids results in energy loss to both atomic nuclei and electrons in the solid. In this article, recent advances in understanding and modeling the additive and competitive effects of nuclear and electronic energy loss on the response of materials to ion irradiation are reviewed. Experimental methods and large-scale atomistic simulations are used to study the separate and combined effects of nuclear and electronic energy loss on ion beam modification of materials. The results demonstrate that nuclear and electronic energy loss can lead to additive effects on irradiation damage production in some materials; while inmore » other materials, the competitive effects of electronic energy loss leads to recovery of damage induced by elastic collision cascades. Lastly, these results have significant implications for ion beam modification of materials, non-thermal recovery of ion implantation damage, and the response of materials to extreme radiation environments.« less

  5. The role of electronic energy loss in ion beam modification of materials

    SciTech Connect

    Weber, William J.; Duffy, Dorothy M.; Thome, Lionel; Zhang, Yanwen

    2014-10-05

    The interaction of energetic ions with solids results in energy loss to both atomic nuclei and electrons in the solid. In this article, recent advances in understanding and modeling the additive and competitive effects of nuclear and electronic energy loss on the response of materials to ion irradiation are reviewed. Experimental methods and large-scale atomistic simulations are used to study the separate and combined effects of nuclear and electronic energy loss on ion beam modification of materials. The results demonstrate that nuclear and electronic energy loss can lead to additive effects on irradiation damage production in some materials; while in other materials, the competitive effects of electronic energy loss leads to recovery of damage induced by elastic collision cascades. Lastly, these results have significant implications for ion beam modification of materials, non-thermal recovery of ion implantation damage, and the response of materials to extreme radiation environments.

  6. Beam Losses and Background Loads on Collider Detectors Due to Beam-Gas Interactions in the LHC

    SciTech Connect

    Drozhdin, A.I.; Mokhov, N.V.; Striganov, S.I.; /Fermilab

    2009-04-01

    With a fully-operational high-efficient collimation system in the LHC, nuclear interactions of circulating protons with residual gas in the machine beam pipe can be a major source of beam losses in the vicinity of the collider detectors, responsible for the machine-induced backgrounds. Realistic modeling of Coulomb scattering, elastic and inelastic interactions of 7-TeV protons with nuclei in the vacuum chamber of the cold and warm sections of the LHC ring--with an appropriate pressure profile--is performed with the STRUCT and MARS15 codes. Multi-turn tracking of the primary beams, propagation of secondaries through the lattice, their interception by the tertiary collimators TCT as well as properties of corresponding particle distributions at the CMS and ATLAS detectors are studied in great detail and results presented in this paper.

  7. Measured and simulated heavy-ion beam loss patterns at the CERN Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Hermes, P. D.; Bruce, R.; Jowett, J. M.; Redaelli, S.; Salvachua Ferrando, B.; Valentino, G.; Wollmann, D.

    2016-05-01

    The Large Hadron Collider (LHC) at CERN pushes forward to new regimes in terms of beam energy and intensity. In view of the combination of very energetic and intense beams together with sensitive machine components, in particular the superconducting magnets, the LHC is equipped with a collimation system to provide protection and intercept uncontrolled beam losses. Beam losses could cause a superconducting magnet to quench, or in the worst case, damage the hardware. The collimation system, which is optimized to provide a good protection with proton beams, has shown a cleaning efficiency with heavy-ion beams which is worse by up to two orders of magnitude. The reason for this reduced cleaning efficiency is the fragmentation of heavy-ion beams into isotopes with a different mass to charge ratios because of the interaction with the collimator material. In order to ensure sufficient collimation performance in future ion runs, a detailed theoretical understanding of ion collimation is needed. The simulation of heavy-ion collimation must include processes in which 82+208Pb ions fragment into dozens of new isotopes. The ions and their fragments must be tracked inside the magnetic lattice of the LHC to determine their loss positions. This paper gives an overview of physical processes important for the description of heavy-ion loss patterns. Loss maps simulated by means of the two tools ICOSIM [1,2] and the newly developed STIER (SixTrack with Ion-Equivalent Rigidities) are compared with experimental data measured during LHC operation. The comparison shows that the tool STIER is in better agreement.

  8. Development of silicon detectors for Beam Loss Monitoring at HL-LHC

    NASA Astrophysics Data System (ADS)

    Verbitskaya, E.; Eremin, V.; Zabrodskii, A.; Bogdanov, A.; Shepelev, A.; Dehning, B.; Bartosik, M. R.; Alexopoulos, A.; Glaser, M.; Ravotti, F.; Sapinski, M.; Härkönen, J.; Egorov, N.; Galkin, A.

    2017-03-01

    Silicon detectors were proposed as novel Beam Loss Monitors (BLM) for the control of the radiation environment in the vicinity of the superconductive magnets of the High-Luminosity Large Hadron Collider. The present work is aimed at enhancing the BLM sensitivity and therefore the capability of triggering the beam abort system before a critical radiation load hits the superconductive coils. We report here the results of three in situ irradiation tests of Si detectors carried out at the CERN PS at 1.9–4.2 K. The main experimental result is that all silicon detectors survived irradiation up to 1.22× 1016 p/cm2. The third test, focused on the detailed characterization of the detectors with standard (300 μm) and reduced (100 μm) thicknesses, showed only a marginal difference in the sensitivity of thinned detectors in the entire fluence range and a smaller rate of signal degradation that promotes their use as BLMs. The irradiation campaigns produced new information on radiation damage and carrier transport in Si detectors irradiated at the temperatures of 1.9–4.2 K. The results were encouraging and permitted to initiate the production of the first BLM prototype modules which were installed at the end of the vessel containing the superconductive coil of a LHC magnet immersed in superfluid helium to be able to test the silicon detectors in real operational conditions.

  9. Non-uniform space charge controlled KTN beam deflector

    NASA Astrophysics Data System (ADS)

    Chao, Ju-Hung; Zhu, Wenbin; Chen, Chang-Jiang; Yin, Stuart; Hoffman, Robert C.

    2016-09-01

    A non-uniform space charge-controlled KTN beam deflector is presented and analyzed. We found that a non-uniform space charge can result in a non-uniform beam deflection angles. This effect can be useful for some applications such as electric field controlled beam separation. However, a non-uniform space charge needs to be avoided if one wants uniform beam deflection throughout the entire crystal.

  10. Anomalous Beam-Ion Loss in TFTR Reversed Magnetic Shear Plasmas

    SciTech Connect

    Ruskov, E.; Bell, M.; Budny, R.V.; McCune, D.C.; Medley, S.S.; Redi, M.H.; Scott, S.; Synakowski, E.J.; von Goeler, S.; White, R.B.; Zweben, S.J.

    1999-02-01

    Anomalous beam-ion loss has been observed in an experiment with short tritium beam pulses injected into deuterium-beam-heated Tokamak Fusion Test Reactor plasmas (P{sub NBI}=15 thinspthinspMW) with reversed magnetic shear (RS). Comparisons of the measured total 14thinspthinspMeV neutron emission, the neutron flux along eight radial locations, and the perpendicular plasma stored energy with predictions from an extensive set of TRANSP simulations suggest that about 40{percent} beam power is lost on a time scale much shorter than the tritium beam pulse length {Delta}t=70 thinspthinspms. In contrast with recent results [K. Tobita {ital et al.,} Nucl.thinspthinspFusion {bold 37}, 1583 (1997)] from RS experiments at JT-60U, we were not able to show conclusively that magnetic field ripple is responsible for this anomaly. {copyright} {ital 1999} {ital The American Physical Society}

  11. Anomalous Beam-Ion Loss in TFTR Reversed Magnetic Shear Plasmas

    NASA Astrophysics Data System (ADS)

    Ruskov, E.; Bell, M.; Budny, R. V.; McCune, D. C.; Medley, S. S.; Redi, M. H.; Scott, S.; Synakowski, E. J.; von Goeler, S.; White, R. B.; Zweben, S. J.

    1999-02-01

    Anomalous beam-ion loss has been observed in an experiment with short tritium beam pulses injected into deuterium-beam-heated Tokamak Fusion Test Reactor plasmas ( PNBI = 15 MW) with reversed magnetic shear (RS). Comparisons of the measured total 14 MeV neutron emission, the neutron flux along eight radial locations, and the perpendicular plasma stored energy with predictions from an extensive set of TRANSP simulations suggest that about 40% beam power is lost on a time scale much shorter than the tritium beam pulse length Δt = 70 ms. In contrast with recent results [K. Tobita et al., Nucl. Fusion 37, 1583 (1997)] from RS experiments at JT-60U, we were not able to show conclusively that magnetic field ripple is responsible for this anomaly.

  12. Link between diffraction losses and light beam cross section in laser with telescopic resonator

    SciTech Connect

    Dmitriev, A.K.; Nekrasov, Yu.V.

    1987-06-01

    The light beam cross section change in a laser and its link with the diffraction losses during the telescopic converter defocusing is discussed. In addition, the measurements of the resonator astigmatism compensation by the Brewster window are carried out. It is demonstrated that in the resonator stability region, the light beam cross section is well described by the expression using the transmission matrix elements, the simplified model for the diffraction qualitatively correlates with the test data, and the mirror astigmatism due to the inclined light beam incidence is compensated for by Brewster's window.

  13. Analysis of the Pipe Heat Loss of the Water Flow Calorimetry System in EAST Neutral Beam Injector

    NASA Astrophysics Data System (ADS)

    Hu, Chundong; Chen, Yu; Xu, Yongjian; Yu, Ling; Li, Xiang; Zhang, Weitang

    2016-11-01

    Neutral beam injection heating is one of the main auxiliary heating methods in controllable nuclear fusion research. In the EAST neutral beam injector, a water flow calorimetry (WFC) system is applied to measure the heat load on the electrode system of the ion source and the heat loading components of the beamline. Due to the heat loss in the return water pipe, there are some measuring errors for the current WFC system. In this paper, the errors were measured experimentally and analyzed theoretically, which lay a basis for the exact calculation of beam power deposition distribution and neutralization efficiency. supported by the National Magnetic Confinement Fusion Science Program of China (No. 2013GB101001) and the International Science & Technology Cooperation Program of China (No. 2014DFG61950)

  14. Beam screen cryogenic control improvements for the LHC run 2

    NASA Astrophysics Data System (ADS)

    Bradu, B.; Rogez, E.; Blanco-Viñuela, E.; Ferlin, G.; Tovar-Gonzalez, A.

    2017-02-01

    This paper presents the improvements made on the cryogenic control system for the LHC beam screens. The regulation objective is to maintain an acceptable temperature range around 20 K which simultaneously ensures a good LHC beam vacuum and limits cryogenic heat loads. In total, through the 27 km of the LHC machine, there are 485 regulation loops affected by beam disturbances. Due to the increase of the LHC performance during Run 2, standard PID controllers cannot keeps the temperature transients of the beam screens within desired limits. Several alternative control techniques have been studied and validated using dynamic simulation and then deployed on the LHC cryogenic control system in 2015. The main contribution is the addition of a feed-forward control in order to compensate the beam effects on the beam screen temperature based on the main beam parameters of the machine in real time.

  15. Electron beam loss assumptions for ELI-NPMEGa-ray radioprotection analysis

    SciTech Connect

    Deis, G A

    2011-10-06

    The ELI-NP project is now working on the design of their conventional facility. Dr. Gheorghe Cata-Danil recently requested that I provide them with information on the location and amount of electron-beam loss in the MEGa-ray source they have proposed for ELI-NP. This memo is intended to document that information, for transmission to ELI-NP. The ELI-NP MEGa-ray source, as presently proposed, consists of two x-band accelerator sections separated by a large chicane, as show in figure 1. The basic parameters of the machine that are pertinent for specifying the radiation source terms are shown in table 1. These are the parameters of the intentionall-produced photobeam. In addition to the photobeam, the electron gun and accelerator will produce 'dark current' that originates throughout the RF structures (that is, distributed along the accelerator axis) and therefore has a distribution of energy below the energy of the photobeam. Because it is emitted from surfaces inside the RF structures, much of it is not transported through the accelerator and is lost in the accelerator RF structures. A large fraction of the total dark current is produced in the photogun and lost at the entrance of the 1st accelerator RF structure. Important sources of radiation during operation are beam alignment screens that are used for observing the image of the electron beam, during adjustment of beam steering and for general diagnostic purposes. Each screen consists of a 1 mm thick Ce:YAG plate that is moved into the path of the beam when desired. This destroys the electron beam, spraying all beam current into the structures downstream of the screen. Only one screen is inserted at a time. These screens may be located after each accelerator RF structure, and after each set of bend magnets, as shown in figure 3. The photobeam energy and currents at each location are listed in table 2; for simplicity, the dark current energy is (conseratively) assumed to be the same as the photobeam energy. In

  16. Numerical study on wave-induced beam ion prompt losses in DIII-D tokamak

    DOE PAGES

    Feng, Zhichen; Zhu, Jia; Fu, Guo -Yong; ...

    2017-08-30

    A numerical study is performed on the coherent beam ion prompt losses driven by Alfven eigenmodes (AEs) in DIII-D plasmas using realistic parameters and beam ion deposition profiles. The synthetic signal of a fast-ion loss detector (FILD) is calculated for a single AE mode. The first harmonic of the calculated FILD signal is linearly proportional to the AE amplitude with the same AE frequency in agreement with the experimental measurement. The calculated second harmonic is proportional to the square of the first harmonic for typical AE amplitudes. The coefficient of quadratic scaling is found to be sensitive to the AEmore » mode width. The second part of this work considers the AE drive due to coherent prompt loss. As a result, it is shown that the loss-induced mode drive is much smaller than the previous estimate and can be ignored for mode stability.« less

  17. Cavity loss factors of non-relativistic beams for Project X

    SciTech Connect

    Lunin, A.; Yakovlev, V.; Kazakov, S.; /Fermilab

    2011-03-01

    Cavity loss factor calculation is an important part of the total cryolosses estimation for the super conductive (SC) accelerating structures. There are two approaches how to calculate cavity loss factors, the integration of a wake potential over the bunch profile and the addition of loss factors for individual cavity modes. We applied both methods in order to get reliable results for non-relativistic beam. The time domain CST solver was used for a wake potential calculation and the frequency domain HFSS code was used for the cavity eigenmodes spectrum findings. Finally we present the results of cavity loss factors simulations for a non-relativistic part of the ProjectX and analyze it for various beam parameters.

  18. APPARATUS FOR ELECTRON BEAM HEATING CONTROL

    DOEpatents

    Jones, W.H.; Reece, J.B.

    1962-09-18

    An improved electron beam welding or melting apparatus is designed which utilizes a high voltage rectifier operating below its temperature saturation region to decrease variations in electron beam current which normally result from the gas generated in such apparatus. (AEC)

  19. Radiation losses in PLT during neutral beam and ICRF heating experiments

    SciTech Connect

    Suckewer, S.; Hinnov, E.; Hwang, D.

    1981-02-01

    Radiation and charge exchange losses in the PLT tokamak are compared for discharges with ohmic heating only (OH), and with additional heating by neutral beams (NB) or RF in the ion cyclotron frequency range (ICRF). Spectroscopic, bolometric and soft x-ray diagnostics were used. The effects of discharge cleaning, vacuum wall gettering, and rate of gas inlet on radiation losses from OH plasmas and the correlation between radiation from plasma core and edge temperatures are discussed.

  20. Summary Report on Beam and Radiation Generation, Monitoring and Control

    SciTech Connect

    Gordon, D. F.; Power, J. G.

    2009-01-22

    The discussions of the working group on beam and radiation generation, monitoring, and control (working group 6) at the 2008 advanced accelerator concepts workshop are summarized. The discussions concerned electron injectors, phase space manipulation, beam diagnostics, pulse train generation, intense beam physics, and radiation generation.

  1. Controlling the Focus in Electron-Beam Welders

    NASA Technical Reports Server (NTRS)

    Macfarlane, D. I.; Spiegel, K. W.

    1984-01-01

    Detector using two whirling wires measures focus of beam in electronbeam welder. Multiple-wire beam-sampling method provides for simple nullmeter focus indication easily controlled by operator. Detector not only operates at high beam currents but eliminates need for oscilloscope.

  2. Neutron doses due to beam losses in a novel concept of a proton therapy gantry

    NASA Astrophysics Data System (ADS)

    Talanov, V.; Kiselev, D. C.; Meer, D.; Rizzoglio, V.; Schippers, J. M.; Seidel, M.; Wohlmuther, M.

    2017-07-01

    A novel design of a gantry for proton therapy is investigated in which a degrader and emittance limiting collimators are mounted on the gantry. Due to the interactions of protons in these components there will be an additional neutron dose at the location where a patient is positioned during a proton therapy. The results of numerical study of this additional dose are presented. Neutron prompt dose at the patient position is estimated through the Monte Carlo simulation using the MCNPX 2.7.0 particle transport code. Secondary neutron and photon fluxes from the distinct beam loss points are taken into consideration and the resulting dose is calculated using realistic estimates of beam losses. The dependence of the dose on the beam energy and individual impacts of each loss point on the total dose at the patient position as well as on critical beam line components are estimated and potential design constraints are discussed. It has been found that compared with a conventional gantry the expected additional dose is higher but the optimization of the beam line configuration and additional shielding shall help to reduce the dose to an acceptable value.

  3. Heavy ion beam loss mechanisms at an electron-ion collider

    NASA Astrophysics Data System (ADS)

    Klein, Spencer R.

    2014-12-01

    There are currently several proposals to build a high-luminosity electron-ion collider, to study the spin structure of matter and measure parton densities in heavy nuclei, and to search for gluon saturation and new phenomena like the colored glass condensate. These measurements require operation with heavy nuclei. We calculate the cross sections for two important processes that will affect accelerator and detector operations: bound-free pair production and Coulomb excitation of the nuclei. Both of these reactions have large cross sections, 28-56 mb, which can lead to beam ion losses, produce beams of particles with altered charge:mass ratio, and produce a large flux of neutrons in zero degree calorimeters. The loss of beam particles limits the sustainable electron-ion luminosity to levels of several times 1032/cm2/s .

  4. Distributed beam loss monitor based on the Cherenkov effect in an optical fiber

    NASA Astrophysics Data System (ADS)

    Maltseva, Yu; Emanov, F. A.; Petrenko, A. V.; Prisekin, V. G.

    2015-05-01

    This review discusses a distributed beam loss monitor which is based on the Cherenkov effect in an optical fiber and which has been installed at the VEPP-5 Injection Complex at the Budker Institute of Nuclear Physics. The principle of the device operation consists in detecting the Cherenkov radiation generated in an optical fiber by relativistic charged particles that are produced in an electromagnetic shower when highly relativistic beam particles (electrons or positrons) hit the accelerator vacuum chamber wall. Our experiments used a photomultiplier tube (PMT) to detect the Cherenkov light. Knowing when the PMT signal arrives tells us where the beam loss occurs. Using a 20-m-long optical fiber allowed a detector spatial resolution of 3 m. The way to improve the resolution is to optimize the monitor working conditions and optical fiber and PMT parameters, potentially leading to a resolution of as fine as 0.5 m according to our estimates.

  5. Generation of stochastic electromagnetic beams with complete controllable coherence.

    PubMed

    Chen, Xudong; Chang, Chengcheng; Chen, Ziyang; Lin, Zhili; Pu, Jixiong

    2016-09-19

    We generate a stochastic electromagnetic beam (SEB) with complete controllable coherence, that is, the coherence degree can be controlled independently along two mutually perpendicular directions. We control the coherence of the SEB by adjusting the phase modulation magnitude applied onto two crossed phase only spatial light modulators. We measure the beam's coherence properties using Young's interference experiment, as well as the beam propagation factor. It is shown that the experimental results are consistent with our theoretical predictions.

  6. Feedback control of optical beam spatial profiles using thermal lensing.

    PubMed

    Liu, Zhanwei; Fulda, Paul; Arain, Muzammil A; Williams, Luke; Mueller, Guido; Tanner, D B; Reitze, D H

    2013-09-10

    A method for active control of the spatial profile of a laser beam using adaptive thermal lensing is described. A segmented electrical heater was used to generate thermal gradients across a transmissive optical element, resulting in a controllable thermal lens. The segmented heater also allows the generation of cylindrical lenses, and provides the capability to steer the beam in both horizontal and vertical planes. Using this device as an actuator, a feedback control loop was developed to stabilize the beam size and position.

  7. A Cesium Beam Frequency Standard with Microprocessor Control,

    DTIC Science & Technology

    Frequency, *Control, *Symposia, *Electron beams, *Cesium, *Microprocessors, Laboratory tests, Frequency standards, Performance(Engineering), Reliability, Time , State of the art, Computers, Data acquisition

  8. Observations of neutral beam and ICRF tail ion losses due to Alfven modes in TFTR

    SciTech Connect

    Darrow, D.S.; Zweben, S.J.; Chang, Z.

    1996-04-01

    Fast ion losses resulting from MHD modes at the Alfven frequency, such as the TAE, have been observed in TFTR. The modes have been driven both by neutral beam ions, at low B{sub T}, and by H-minority ICRF tail ions at higher B{sub T}. The measurements indicate that the loss rate varies linearly with the mode amplitude, and that the fast ion losses during the mode activity can be significant, e.g. up to 10% of the input power is lost in the worst case.

  9. Specialty flat-top beam delivery fibers with controlled beam parameter product

    NASA Astrophysics Data System (ADS)

    Jollivet, C.; Farley, K.; Conroy, M.; Abramczyk, J.; Belke, S.; Becker, F.; Tankala, K.

    2016-03-01

    Beam delivery fibers have been used widely for transporting the optical beams from the laser to the subject of irradiation in a variety of markets including industrial, medical and defense applications. Standard beam delivery fibers range from 50 to 1500 μm core diameter and are used to guide CW or pulsed laser light, generated by solid state, fiber or diode lasers. Here, we introduce a novel fiber technology capable of simultaneously controlling the beam profile and the angular divergence of single-mode (SM) and multi-mode (MM) beams using a single-optical fiber. Results of beam transformation from a SM to a MM beam with flat-top intensity profile are presented in the case of a controlled BPP at 3.8 mm*mrad. The scaling capabilities of this flat-top fiber design to achieve a range of BPP values while ensuring a flat-top beam profile are discussed. In addition, we demonstrate, for the first time to the best of our knowledge, the homogenizer capabilities of this novel technology, able to transform random MM beams into uniform flat-top beam profiles with very limited impact on the beam brightness. This study is concluded with a discussion on the scalability of this fiber technology to fit from 50 up to 1500 μm core fibers and its potential for a broader range of applications.

  10. Reliability of Beam Loss Monitors System for the Large Hadron Collider

    SciTech Connect

    Guaglio, G.; Dehning, B.; Santoni, C.

    2004-11-10

    The employment of superconducting magnets in high energy colliders opens challenging failure scenarios and brings new criticalities for the whole system protection. For the LHC beam loss protection system, the failure rate and the availability requirements have been evaluated using the Safety Integrity Level (SIL) approach. A downtime cost evaluation is used as input for the SIL approach. The most critical systems, which contribute to the final SIL value, are the dump system, the interlock system, the beam loss monitors system and the energy monitor system. The Beam Loss Monitors System (BLMS) is critical for short and intense particle losses, while at medium and higher loss time it is assisted by other systems, such as the quench protection system and the cryogenic system. For BLMS, hardware and software have been evaluated in detail. The reliability input figures have been collected using historical data from the SPS, using temperature and radiation damage experimental data as well as using standard databases. All the data have been processed by reliability software (Isograph). The analysis ranges from the components data to the system configuration.

  11. Shielding NSLS-II light source: Importance of geometry for calculating radiation levels from beam losses

    SciTech Connect

    Kramer, S. L.; Ghosh, V. J.; Breitfeller, M.; Wahl, W.

    2016-08-10

    We present that third generation high brightness light sources are designed to have low emittance and high current beams, which contribute to higher beam loss rates that will be compensated by Top-Off injection. Shielding for these higher loss rates will be critical to protect the projected higher occupancy factors for the users. Top-Off injection requires a full energy injector, which will demand greater consideration of the potential abnormal beam miss-steering and localized losses that could occur. The high energy electron injection beam produces significantly higher neutron component dose to the experimental floor than a lower energy beam injection and ramped operations. Minimizing this dose will require adequate knowledge of where the miss-steered beam can occur and sufficient EM shielding close to the loss point, in order to attenuate the energy of the particles in the EM shower below the neutron production threshold (<10 MeV), which will spread the incident energy on the bulk shield walls and thereby the dose penetrating the shield walls. Designing supplemental shielding near the loss point using the analytic shielding model is shown to be inadequate because of its lack of geometry specification for the EM shower process. To predict the dose rates outside the tunnel requires detailed description of the geometry and materials that the beam losses will encounter inside the tunnel. Modern radiation shielding Monte-Carlo codes, like FLUKA, can handle this geometric description of the radiation transport process in sufficient detail, allowing accurate predictions of the dose rates expected and the ability to show weaknesses in the design before a high radiation incident occurs. The effort required to adequately define the accelerator geometry for these codes has been greatly reduced with the implementation of the graphical interface of FLAIR to FLUKA. In conclusion, this made the effective shielding process for NSLS-II quite accurate and reliable. The principles

  12. Shielding NSLS-II light source: Importance of geometry for calculating radiation levels from beam losses

    DOE PAGES

    Kramer, S. L.; Ghosh, V. J.; Breitfeller, M.; ...

    2016-08-10

    We present that third generation high brightness light sources are designed to have low emittance and high current beams, which contribute to higher beam loss rates that will be compensated by Top-Off injection. Shielding for these higher loss rates will be critical to protect the projected higher occupancy factors for the users. Top-Off injection requires a full energy injector, which will demand greater consideration of the potential abnormal beam miss-steering and localized losses that could occur. The high energy electron injection beam produces significantly higher neutron component dose to the experimental floor than a lower energy beam injection and rampedmore » operations. Minimizing this dose will require adequate knowledge of where the miss-steered beam can occur and sufficient EM shielding close to the loss point, in order to attenuate the energy of the particles in the EM shower below the neutron production threshold (<10 MeV), which will spread the incident energy on the bulk shield walls and thereby the dose penetrating the shield walls. Designing supplemental shielding near the loss point using the analytic shielding model is shown to be inadequate because of its lack of geometry specification for the EM shower process. To predict the dose rates outside the tunnel requires detailed description of the geometry and materials that the beam losses will encounter inside the tunnel. Modern radiation shielding Monte-Carlo codes, like FLUKA, can handle this geometric description of the radiation transport process in sufficient detail, allowing accurate predictions of the dose rates expected and the ability to show weaknesses in the design before a high radiation incident occurs. The effort required to adequately define the accelerator geometry for these codes has been greatly reduced with the implementation of the graphical interface of FLAIR to FLUKA. In conclusion, this made the effective shielding process for NSLS-II quite accurate and reliable. The

  13. Controllable Airy-like beams induced by tunable phase patterns

    NASA Astrophysics Data System (ADS)

    Li, D.; Qian, Y.

    2016-01-01

    We propose and experimentally observe a novel family of Airy-like beams. First, we theoretically investigate the physical generation of our proposed controllable Airy-like beams by introducing a rotation angle factor into the phase function, which can regulate and flexibly control the beam wavefront. Meanwhile we can also readily control the main lobes of these beams to follow appointed parabolic trajectories using the rotation angle factor. We also demonstrate that the controllable Airy-like beams lack the properties of being diffraction-free and self-healing. The experiments are performed and the results are in accord with the theoretical simulations. We believe that the intriguing characteristics of our proposed Airy-like beams could provide more degrees of freedom, and are likely to give rise to new applications and lend versatility to the emerging field.

  14. Background gas density and beam losses in NIO1 beam source

    NASA Astrophysics Data System (ADS)

    Sartori, E.; Veltri, P.; Cavenago, M.; Serianni, G.

    2016-02-01

    NIO1 (Negative Ion Optimization 1) is a versatile ion source designed to study the physics of production and acceleration of H- beams up to 60 keV. In ion sources, the gas is steadily injected in the plasma source to sustain the discharge, while high vacuum is maintained by a dedicated pumping system located in the vessel. In this paper, the three dimensional gas flow in NIO1 is studied in the molecular flow regime by the Avocado code. The analysis of the gas density profile along the accelerator considers the influence of effective gas temperature in the source, of the gas temperature accommodation by collisions at walls, and of the gas particle mass. The calculated source and vessel pressures are compared with experimental measurements in NIO1 during steady gas injection.

  15. Background gas density and beam losses in NIO1 beam source

    SciTech Connect

    Sartori, E. Veltri, P.; Serianni, G.; Cavenago, M.

    2016-02-15

    NIO1 (Negative Ion Optimization 1) is a versatile ion source designed to study the physics of production and acceleration of H- beams up to 60 keV. In ion sources, the gas is steadily injected in the plasma source to sustain the discharge, while high vacuum is maintained by a dedicated pumping system located in the vessel. In this paper, the three dimensional gas flow in NIO1 is studied in the molecular flow regime by the Avocado code. The analysis of the gas density profile along the accelerator considers the influence of effective gas temperature in the source, of the gas temperature accommodation by collisions at walls, and of the gas particle mass. The calculated source and vessel pressures are compared with experimental measurements in NIO1 during steady gas injection.

  16. Evaluation of Beam Loss and Energy Depositions for a Possible Phase II Design for LHC Collimation

    SciTech Connect

    Lari, L.; Assmann, R.; Bracco, C.; Brugger, M.; Cerutti, F.; Doyle, E.; Ferrari, A.; Keller, L.; Lundgren, S.; Markiewicz, Thomas W.; Mauri, M.; Redaelli, S.; Sarchiapone, L.; Smith, J.; Vlachoudis, V.; Weiler, T.; /CERN

    2011-11-07

    The LHC beams are designed to have high stability and to be stored for many hours. The nominal beam intensity lifetime is expected to be of the order of 20h. The Phase II collimation system has to be able to handle particle losses in stable physics conditions at 7 TeV in order to avoid beam aborts and to allow correction of parameters and restoration to nominal conditions. Monte Carlo simulations are needed in order to evaluate the behavior of metallic high-Z collimators during operation scenarios using a realistic distribution of losses, which is a mix of the three limiting halo cases. Moreover, the consequences in the IR7 insertion of the worst (case) abnormal beam loss are evaluated. The case refers to a spontaneous trigger of the horizontal extraction kicker at top energy, when Phase II collimators are used. These studies are an important input for engineering design of the collimation Phase II system and for the evaluation of their effect on adjacent components. The goal is to build collimators that can survive the expected conditions during LHC stable physics runs, in order to avoid quenches of the SC magnets and to protect other LHC equipments.

  17. Evaluation of Beam Losses And Energy Deposition for a Possible Phase II Design for LHC Collimation

    SciTech Connect

    Lari, L.; Assmann, R.W.; Bracco, C.; Brugger, M.; Cerutti, F.; Ferrari, A.; Mauri, M.; Redaelli, S.; Sarchiapone, L.; Vlachoudis, Vasilis; Weiler, Th.; Doyle, J.E.; Keller, L.; Lundgren, S.A.; Markiewicz, Thomas W.; Smith, J.C.; Lari, L.; /LPHE, Lausanne

    2011-11-01

    The Large Hadron Collider (LHC) beams are designed to have high stability and to be stored for many hours. The nominal beam intensity lifetime is expected to be of the order of 20h. The Phase II collimation system has to be able to handle particle losses in stable physics conditions at 7 TeV in order to avoid beam aborts and to allow correction of parameters and restoration to nominal conditions. Monte Carlo simulations are needed in order to evaluate the behavior of metallic high-Z collimators during operation scenarios using a realistic distribution of losses, which is a mix of the three limiting halo cases. Moreover, the consequences in the IR7 insertion of the worst (case) abnormal beam loss are evaluated. The case refers to a spontaneous trigger of the horizontal extraction kicker at top energy, when Phase II collimators are used. These studies are an important input for engineering design of the collimation Phase II system and for the evaluation of their effect on adjacent components. The goal is to build collimators that can survive the expected conditions during LHC stable physics runs, in order to avoid quenches of the SC magnets and to protect other LHC equipments.

  18. Method for measuring and controlling beam current in ion beam processing

    DOEpatents

    Kearney, Patrick A.; Burkhart, Scott C.

    2003-04-29

    A method for producing film thickness control of ion beam sputter deposition films. Great improvements in film thickness control is accomplished by keeping the total current supplied to both the beam and suppressor grids of a radio frequency (RF) in beam source constant, rather than just the current supplied to the beam grid. By controlling both currents, using this method, deposition rates are more stable, and this allows the deposition of layers with extremely well controlled thicknesses to about 0.1%. The method is carried out by calculating deposition rates based on the total of the suppressor and beam currents and maintaining the total current constant by adjusting RF power which gives more consistent values.

  19. Modeling of beam loss in Tevatron and backgrounds in the BTeV detector

    SciTech Connect

    Alexandr I. Drozhdin; Nikolai V. Mokhov

    2004-07-07

    Detailed STRUCT simulations are performed on beam loss rates in the vicinity of the BTeV detector in the Tevatron CO interaction region due to beam-gas nuclear elastic interactions and out-scattering from the collimation system. Corresponding showers induced in the machine components and background rates in BTeV are modeled with the MARS14 code. It is shown that the combination of a steel collimator and concrete shielding wall located in front of the detector can reduce the accelerator-related background rates in the detector by an order of magnitude.

  20. Polarisation splitting of laser beams by large angles with minimal reflection losses

    SciTech Connect

    Davydov, B L

    2006-05-31

    New crystal anisotropic prisms for splitting orthogonally polarised components of laser radiation by large angles with minimal reflection losses caused by the Brewster refraction and total internal reflection of polarised waves from the crystal-air interface are considered and the method for their calculation is described. It is shown that, by assembling glue-free combinations of two or three prisms, thermally stable beamsplitters can be fabricated, which are free from the beam astigmatism and the wave dispersion of the output angles of the beams. The parameters and properties of new beamsplitters are presented in a convenient form in figures and tables. (laser applications and other topics in quantum electronics)

  1. Laser Beam Duct Pressure Controller System.

    DTIC Science & Technology

    the axial flow of a conditioning gas within the laser beam duct, by matching the time rate of change of the pressure of the flowing conditioning gas...to the time rate of change of the pressure in the cavity of an operably associated laser beam turret.

  2. DEVICE CONTROL TOOL FOR CEBAF BEAM DIAGNOSTICS SOFTWARE

    SciTech Connect

    Pavel Chevtsov

    2008-02-11

    Continuously monitoring the beam quality in the CEBAF accelerator, a variety of beam diagnostics software created at Jefferson Lab makes a significant contribution to very high availability of the machine for nuclear physics experiments. The interface between this software and beam instrumentation hardware components is provided by a device control tool, which is optimized for beam diagnostics tasks. As a part of the device/driver development framework at Jefferson Lab, this tool is very easy to support and extend to integrate new beam instrumentation components. All device control functions are based on the configuration (ASCII text) files that completely define the used hardware interface standards (CAMAC, VME, RS-232, GPIB, etc.) and communication protocols. The paper presents the main elements of the device control tool for beam diagnostics software at Jefferson Lab.

  3. Michelson interferometric fiber sensor for beam vibration control

    NASA Astrophysics Data System (ADS)

    Chou, Chan-Shin

    1994-05-01

    A fiber-optic Michelson interferometer is employed for sensing the vibration of a cantilevered beam. A small section of the sensing fiber arm is attached to the beam to sense the vibration of the beam. The active homodyne technique is used to obtain an electrical output which is proportional to the vibrational signal of the beam. A closed-loop control system comprises a pair of sensors and actuators, which are mounted nearly at the same point of the vibrating body, and an inverting power amplifier. The fiber sensor and a piezoelectric actuator are co- located on the root of the cantilevered beam. The fiber sensed signal is amplified and inverted, then fed into a piezoelectric actuator for exerting a dynamic control force on the body. Experimental results show that vibration of the beam is substantially reduced by applying a single control system with the fiber-optic Michelson interferometric vibration sensor.

  4. Plasma charge current for controlling and monitoring electron beam welding with beam oscillation.

    PubMed

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

    2012-12-14

    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.

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

    PubMed Central

    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

  6. Two beam coherent control in semiconductors

    NASA Astrophysics Data System (ADS)

    Král, P.; Sipe, J. E.

    1998-03-01

    Recently, DC current has been generated in superlatices and bulk semiconductors [1] by a simultaneous excitations with two laser beams, giving one-photon and two-photon transitions with frequencies 2ω, ω. In these experiments directionality of the current can be controlled by the relative phase of the two fields. We develop a methodology, based on nonequilibrium Green functions, describing this phenomenon in the presence of many-particle scattering. In the mean-field level of this approach, simultaneous action of the two fields can be reduced to an effective field with a tunable relative excitation strength for different wave vectors of the Brillouine zone. We derive transport equations for a `quasi'-linear, nonlinear and pulse-like excitations in this effective field. In the weak scattering limit, they agree with the Boltzmann equation with generation rates obtained from the Fermi's Golden Rule [2]. We apply the steady-state `quasi'-linear equations to a model 1D quantum wire in the presence of LA phonons, which serves as a reference system for future calculations in realistic 3D systems. Numerical results for the induced dc current are presented in many details. [1] E. Dupont et al., Phys. Rev. Lett. 74, 3596 (1995); A. Haché et al., Phys. Rev. Lett. 78, 306 (1997). [2] R. Atanasov et al., Phys. Rev. Lett. 76, 1703 (1996).

  7. TFTR neutral beam control and monitoring for DT operations

    SciTech Connect

    O`Connor, T.; Kamperschroer, J.; Chu, J.

    1995-12-31

    Record fusion power output has recently been obtained in TFTR with the injection of deuterium and tritium neutral beams. This significant achievement was due in part to the controls, software, and data processing capabilities added to the neutral beam system for DT operations. Chief among these improvements was the addition of SUN workstations and large dynamic data storage to the existing Central Instrumentation Control and Data Acquisition (CICADA) system. Essentially instantaneous look back over the recent shot history has been provided for most beam waveforms and analysis results. Gas regulation controls allowing remote switchover between deuterium and tritium were also added. With these tools, comparison of the waveforms and data of deuterium and tritium for four test conditioning pulses quickly produced reliable tritium setpoints. Thereafter, all beam conditioning was performed with deuterium, thus saving the tritium supply for the important DT injection shots. The lookback capability also led to modifications of the gas system to improve reliability and to control ceramic valve leakage by backbiasing. Other features added to improve the reliability and availability of DT neutral beam operations included master beamline controls and displays, a beamline thermocouple interlock system, a peak thermocouple display, automatic gas inventory and cryo panel gas loading monitoring, beam notching controls, a display of beam/plasma interlocks, and a feedback system to control beam power based on plasma conditions.

  8. Beam Control for Ion Induction Accelerators

    SciTech Connect

    Sangster, T.C.; Ahle, L.

    2000-02-17

    Coordinated bending and acceleration of an intense space-charge-dominated ion beam has been achieved for the first time. This required the development of a variable waveform, precision, bi-polar high voltage pulser and a precision, high repetition rate induction core modulator. Waveforms applied to the induction cores accelerate the beam as the bi-polar high voltage pulser delivers a voltage ramp to electrostatic dipoles which bend the beam through a 90 degree permanent magnet quadrupole lattice. Further work on emittance minimization is also reported.

  9. Generation and control of Bessel beams based on annular reflections

    NASA Astrophysics Data System (ADS)

    Wang, Yongdong; Qu, Weijuan; Jiao, Lishi; Zhang, Yilei

    2015-05-01

    A straightforward but powerful method to generate Bessel beams with continuous control of spot size, intensity and non-diffraction zone length has been successfully developed and verified based on annular reflections using a digital micromirror device (DMD). Reflective circular ring patterns were loaded in a DMD placed in the focal point of a converging lens to generate Bessel beams with tremendous flexibility and control. A Mach-Zehnder interferometer method was applied to reconstruct the wavefront of the generated beam to prove the successful generation of the Bessel beam. This simple but powerful method has great potential in many applications, such as imaging and particle manipulation.

  10. Analysis of detectability loss through fan-beam x-ray computed tomography reconstruction

    NASA Astrophysics Data System (ADS)

    Sanchez, Adrian A.; Sidky, Emil Y.; Pan, Xiaochuan

    2013-03-01

    We consider detection of a small signal in fan-beam x-ray computed tomography (CT). In order to characterize the loss of intrinsic signal detectability from the projection data (sinogram) domain to the reconstructed image, we analyze the Hotelling observer SNR in each domain. Further, we characterize the loss of Hotelling observer SNR through decomposition into two components: loss of signal detectability which arises due to unequal variance in the noise of separate detector elements and loss of detectability arising from the fact that some noiseless signals have components which lie in the nullspace of a given reconstruction operator. The proposed methodology is investigated for the back-projection ltration (BPF) algorithm developed by our group [2].

  11. Accidental beam loss in superconducting accelerators: Simulations, consequences of accidents and protective measures

    SciTech Connect

    Drozhdin, A.; Mokhov, N.; Parker, B.

    1994-02-01

    The consequences of an accidental beam loss in superconducting accelerators and colliders of the next generation range from the mundane to rather dramatic, i.e., from superconducting magnet quench, to overheating of critical components, to a total destruction of some units via explosion. Specific measures are required to minimize and eliminate such events as much as practical. In this paper we study such accidents taking the Superconducting Supercollider complex as an example. Particle tracking, beam loss and energy deposition calculations were done using the realistic machine simulation with the Monte-Carlo codes MARS 12 and STRUCT. Protective measures for minimizing the damaging effects of prefire and misfire of injection and extraction kicker magnets are proposed here.

  12. A novel fast response and radiation-resistant scintillator detector for beam loss monitor

    NASA Astrophysics Data System (ADS)

    Ji, Y.; Tang, Z.; Li, C.; Li, X.; Shao, M.

    2017-07-01

    At high luminosity area, beam loss monitor with fast response and high radiation resistance is crucial for accelerator operation. In this article, we report the design and test results of a fast response and radiation-resistant scintillator detector as the beam loss monitor for high luminosity collider, especially at low energy region such as RFQ. The detector is consisted of a 2 cm× 2 cm× 0.5 cm LYSO crystal readout by a 6 mm × 6 mm Silicon photomultiplier. Test results from various radioactive sources show that the detector has good sensitivity to photons from tens of keV to several MeV with good linearity and energy resolution (23% for 60 keV γ-ray). For field test, two such detectors are installed outside of the vacuum chamber shell of an 800 MeV electron storage ring. The details of the test and results are introduced.

  13. A Loss Tolerant Rate Controller for Reliable Multicast

    NASA Technical Reports Server (NTRS)

    Montgomery, Todd

    1997-01-01

    This paper describes the design, specification, and performance of a Loss Tolerant Rate Controller (LTRC) for use in controlling reliable multicast senders. The purpose of this rate controller is not to adapt to congestion (or loss) on a per loss report basis (such as per received negative acknowledgment), but instead to use loss report information and perceived state to decide more prudent courses of action for both the short and long term. The goal of this controller is to be responsive to congestion, but not overly reactive to spurious independent loss. Performance of the controller is verified through simulation results.

  14. Precessed electron beam electron energy loss spectroscopy of graphene: Beyond channelling effects

    SciTech Connect

    Yedra, Ll.; Estradé, S.; Torruella, P.; Eljarrat, A.; Peiró, F.; Darbal, A. D.; Weiss, J. K.

    2014-08-04

    The effects of beam precession on the Electron Energy Loss Spectroscopy (EELS) signal of the carbon K edge in a 2 monolayer graphene sheet are studied. In a previous work, we demonstrated the use of precession to compensate for the channeling-induced reduction of EELS signal when in zone axis. In the case of graphene, no enhancement of EELS signal is found in the usual experimental conditions, as graphene is not thick enough to present channeling effects. Interestingly, though it is found that precession makes it possible to increase the collection angle, and, thus, the overall signal, without a loss of signal-to-background ratio.

  15. Influence of enhancement filters in apical bone loss measurement: A cone-beam computed tomography study.

    PubMed

    de Sousa, Emerson-Tavares; Pinheiro, Mayara-Abreu; Maciel, Patrícia-Pereira; Sales, Marcelo-Augusto-Oliveira

    2017-04-01

    The use of cone-beam computed tomography images (CBCT) providing a better assessment of bone injuries, although the sensibility of lesions measurement might be improved by the use of enhancement filters. Objective: This study aimed to analyze the influence of enhancement filters in apical bone loss measurement. Eighteen CBCT cases randomly selected of apical bone loss were evaluated. The analyses were carried out following the evaluation in axial, coronal and sagittal protocols, using enhancement filters as Hard, Normal, and Very Sharp. The variables were statistically analyzed by Friedman and Wilcoxon test, Spearman's rho, and intraclass correlation coefficient. The differences between filters in axial and sagittal protocols were significant (p<0.05); however, this was not observed in the coronal slice. The use of Hard filter demonstrates better results than Very Sharp and Normal filter, improving significantly the bone loss measurement. A strong, significant and positive correlation was noted for all filters (with p< 0.001), such as a strong agreement between the variables, when the Normal filter was used as a reference. The use of enhancement filters increases the sensitivity of alveolar bone loss measurement, with relative advantage for Hard filter. Key words:Cone-Beam computed tomography. endodontics. periapical periodontitis. image enhancement. alveolar bone loss.

  16. Interaction between corrosion crack width and steel loss in RC beams corroded under load

    SciTech Connect

    Malumbela, Goitseone; Alexander, Mark; Moyo, Pilate

    2010-09-15

    This paper presents results and discussions on an experimental study conducted to relate the rate of widening of corrosion cracks with the pattern of corrosion cracks as well as the level of steel corrosion for RC beams (153 x 254 x 3000 mm) that were corroded whilst subjected to varying levels of sustained loads. Steel corrosion was limited to the tensile reinforcement and to a length of 700 mm at the centre of the beams. The rate of widening of corrosion cracks as well as strains on uncracked faces of RC beams was constantly monitored during the corrosion process, along the corrosion region and along other potential cracking faces of beams using a demec gauge. The distribution of the gravimetric mass loss of steel along the corrosion region was measured at the end of the corrosion process. The results obtained showed that: the rate of widening of each corrosion crack is dependent on the overall pattern of the cracks whilst the rate of corrosion is independent of the pattern of corrosion cracks. A mass loss of steel of 1% was found to induce a corrosion crack width of about 0.04 mm.

  17. Design of Electron-Beam Controlled Switches.

    DTIC Science & Technology

    1982-11-24

    considerably depending upon the specific mode used. There now exists a need for the development of these switches in several areas. One area of focus is...the generation and propagation of intense charged particle beams.9 Here, the repetitive capabil- ity of the switch in the closing mode under high...that of beam generation and propagation . In this case the generation of a high voltage pulse (>200 kV) as a result of the fast increase of an opening

  18. Reducing the extraction loss via laser notching the H- beam at the Booster injection revolution frequency

    SciTech Connect

    Yang, Xi; Ankenbrandt, Charles M.; /Fermilab

    2005-05-01

    With the requirement for more protons per hour from Booster, the radiation is a limiting factor. Laser notching the H{sup -} beam at the Booster injection revolution frequency and properly aligning those notches on top of each other at the injection and relative to the trigger of firing extraction kickers can remove most of the extraction loss caused by the slow rise time of the kicker field.

  19. Predicting Loss-of-Control Boundaries Toward a Piloting Aid

    NASA Technical Reports Server (NTRS)

    Barlow, Jonathan; Stepanyan, Vahram; Krishnakumar, Kalmanje

    2012-01-01

    This work presents an approach to predicting loss-of-control with the goal of providing the pilot a decision aid focused on maintaining the pilot's control action within predicted loss-of-control boundaries. The predictive architecture combines quantitative loss-of-control boundaries, a data-based predictive control boundary estimation algorithm and an adaptive prediction method to estimate Markov model parameters in real-time. The data-based loss-of-control boundary estimation algorithm estimates the boundary of a safe set of control inputs that will keep the aircraft within the loss-of-control boundaries for a specified time horizon. The adaptive prediction model generates estimates of the system Markov Parameters, which are used by the data-based loss-of-control boundary estimation algorithm. The combined algorithm is applied to a nonlinear generic transport aircraft to illustrate the features of the architecture.

  20. Optimal control of the ballistic motion of Airy beams.

    PubMed

    Hu, Yi; Zhang, Peng; Lou, Cibo; Huang, Simon; Xu, Jingjun; Chen, Zhigang

    2010-07-01

    We demonstrate the projectile motion of two-dimensional truncated Airy beams in a general ballistic trajectory with controllable range and height. We show that the peak beam intensity can be delivered to any desired location along the trajectory as well as repositioned to a given target after displacement due to propagation through disordered or turbulent media.

  1. Digital Controller For Laser-Beam-Steering Subsystem

    NASA Technical Reports Server (NTRS)

    Ansari, Homayoon

    1995-01-01

    Report presents additional information about proposed apparatus described in "Beam-Steering Subsystem for Laser Communication" (NPO-19069). Discusses design of digital beam-steering control subsystem and, in particular, that part of design pertaining to digital compensation for frequency response of steering mirror.

  2. Laser wakefield accelerated electron beam monitoring and control

    SciTech Connect

    Koga, J. K.; Mori, M.; Kotaki, H.; Esirkepov, T. Zh.; Kiriyama, H.; Kando, M.; Bulanov, S. V.

    2016-03-25

    We will discuss our participation in the ImPACT project, which has as one of its goals the development of an ultra-compact electron accelerator using lasers (< 1 GeV, < 10   m) and the generation of an x-ray beam from the accelerated electrons. Within this context we will discuss our investigation into electron beam monitoring and control. Since laser accelerated electrons will be used for x-ray beam generation combined with an undulator, we will present investigation into the possibilities of the improvement of electron beam emittance through cooling.

  3. The applications of in situ electron energy loss spectroscopy to the study of electron beam nanofabrication.

    PubMed

    Chen, Shiahn J; Howitt, David G; Gierhart, Brian C; Smith, Rosemary L; Collins, Scott D

    2009-06-01

    An in situ electron energy loss spectroscopy (EELS) technique has been developed to investigate the dynamic processes associated with electron-beam nanofabrication on thin membranes. In this article, practical applications germane to e-beam nanofabrication are illustrated with a case study of the drilling of nanometer-sized pores in silicon nitride membranes. This technique involves successive acquisitions of the plasmon-loss and the core-level ionization-loss spectra in real time, both of which provide the information regarding the hole-drilling kinetics, including two respective rates for total mass loss, individual nitrogen and silicon element depletion, and the change of the atomic bonding environment. In addition, the in situ EELS also provides an alternative method for endpoint detection with a potentially higher time resolution than by imaging. On the basis of the time evolution of in situ EELS spectra, a qualitative working model combining knock-on sputtering, irradiation-induced mass transport, and phase separation can be proposed.

  4. Very-high-level neutral-beam control system

    SciTech Connect

    Elischer, V.; Jacobson, V.; Theil, E.

    1981-10-01

    As increasing numbers of neutral beams are added to fusion machines, their operation can consume a significant fraction of a facility's total resources. LBL has developed a very high level control system that allows a neutral beam injector to be treated as a black box with just 2 controls: one to set the beam power and one to set the pulse duration. This 2 knob view allows simple operation and provides a natural base for implementing even higher level controls such as automatic source conditioning.

  5. Reproducible and controllable induction voltage adder for scaled beam experiments

    SciTech Connect

    Sakai, Yasuo; Nakajima, Mitsuo; Horioka, Kazuhiko

    2016-08-15

    A reproducible and controllable induction adder was developed using solid-state switching devices and Finemet cores for scaled beam compression experiments. A gate controlled MOSFET circuit was developed for the controllable voltage driver. The MOSFET circuit drove the induction adder at low magnetization levels of the cores which enabled us to form reproducible modulation voltages with jitter less than 0.3 ns. Preliminary beam compression experiments indicated that the induction adder can improve the reproducibility of modulation voltages and advance the beam physics experiments.

  6. Generation of tunable radially polarized array beams by controllable coherence

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Zhang, Jipeng; Zhu, Shijun; Li, Zhenhua

    2017-05-01

    In this paper, a new method for converting a single radial polarization beam into an arbitrary radially polarized array (RPA) beam such as a radial or rectangular symmetry array in the focal plane by modulating a periodic correlation structure is introduced. The realizability conditions for such source and the beam condition for radiation generated by such source are derived. It is illustrated that both the amplitude and the polarization are controllable by means of initial correlation structure and coherence parameter. Furthermore, by designing the source correlation structure, a tunable NUST-shaped RPA beam is demonstrated, which can find widespread applications in micro-nano engineering. Such a method for generation of arbitrary vector array beams is useful in beam shaping and optical tweezers.

  7. Loss-proof self-accelerating beams and their use in non-paraxial manipulation of particles' trajectories.

    PubMed

    Schley, Ran; Kaminer, Ido; Greenfield, Elad; Bekenstein, Rivka; Lumer, Yaakov; Segev, Mordechai

    2014-10-30

    Self-accelerating beams--shape-preserving bending beams--are attracting great interest, offering applications in many areas such as particle micromanipulation, microscopy, induction of plasma channels, surface plasmons, laser machining, nonlinear frequency conversion and electron beams. Most of these applications involve light-matter interactions, hence their propagation range is limited by absorption. We propose loss-proof accelerating beams that overcome linear and nonlinear losses. These beams, as analytic solutions of Maxwell's equations with losses, propagate in absorbing media while maintaining their peak intensity. While the power such beams carry decays during propagation, the peak intensity and the structure of their main lobe region are maintained over large distances. We use these beams for manipulation of particles in fluids, steering the particles to steeper angles than ever demonstrated. Such beams offer many additional applications, such as loss-proof self-bending plasmons. In transparent media these beams show exponential intensity growth, which facilitates other novel applications in micromanipulation and ignition of nonlinear processes.

  8. Improving the Fermilab Booster Notching Efficiency, Beam Losses and Radiation Levels

    SciTech Connect

    Rakhno, I.L.; Drozhdin, A.I.; Mokhov, N.V.; Sidorov, V.I.; Tropin, I.S.; /Fermilab

    2012-05-14

    A fast vertical 1.08-m long kicker (notcher) located in the Fermilab Booster Long-05 straight section is currently used to remove 3 out of 84 circulating bunches after injection to generate an abort gap. With the maximum magnetic field of 72.5 Gauss, it removes only 87% of the 3-bunch intensity at 400 MeV, with 75% loss on pole tips of the focusing Booster magnets, 11% on the Long-06 collimators, and 1% in the rest of the ring. We propose to improve the notching efficiency and reduce beam loss in the Booster by using three horizontal kickers in the Long-12 section. STRUCT calculations show that using horizontal notchers, one can remove up to 96% of the 3-bunch intensity at 400-700 MeV, directing 95% of it to a new beam dump at the Long-13 section. This fully decouples notching and collimation. The beam dump absorbs most of the impinging proton energy in its jaws. The latter are encapsulated into an appropriate radiation shielding that reduces impact on the machine components, personnel and environment to the tolerable levels. MARS simulations show that corresponding prompt and residual radiation levels can be reduced ten times compared to the current ones.

  9. Creating High-Harmonic Beams with Controlled Orbital Angular Momentum

    NASA Astrophysics Data System (ADS)

    Boyd, Robert W.

    A beam of light with an angle-dependent phase Φ = lϕ , where ϕ is the azimuthal coordinate, about the beam axis carries an orbital angular momentum (OAM) of lℏ per photon. Such beams have been exploited to provide superresolution in visible-light microscopy. The ability to create extreme ultraviolet or soft-x-ray beams with controllable OAM would be a critical step towards extending superresolution methods to extremely small feature size. Here we show that OAM is conserved during the process of high-harmonic generation (HHG). Experimentally, we use a fundamental beam with l = 1 and interferometrically determine that the q-th harmonic has an OAM quantum number l equal to its harmonic order q. We also show theoretically how to couple an arbitrary low value of the OAM quantum number l to any harmonic order q in a controlled manner. Our results open a route to microscopy on the molecular, or even submolecular, scale.

  10. Creating high-harmonic beams with controlled orbital angular momentum.

    PubMed

    Gariepy, Genevieve; Leach, Jonathan; Kim, Kyung Taec; Hammond, T J; Frumker, E; Boyd, Robert W; Corkum, P B

    2014-10-10

    A beam with an angular-dependant phase Φ = ℓϕ about the beam axis carries an orbital angular momentum of ℓℏ per photon. Such beams are exploited to provide superresolution in microscopy. Creating extreme ultraviolet or soft-x-ray beams with controllable orbital angular momentum is a critical step towards extending superresolution to much higher spatial resolution. We show that orbital angular momentum is conserved during high-harmonic generation. Experimentally, we use a fundamental beam with |ℓ| = 1 and interferometrically determine that the harmonics each have orbital angular momentum equal to their harmonic number. Theoretically, we show how any small value of orbital angular momentum can be coupled to any harmonic in a controlled manner. Our results open a route to microscopy on the molecular, or even submolecular, scale.

  11. Creating High-Harmonic Beams with Controlled Orbital Angular Momentum

    NASA Astrophysics Data System (ADS)

    Gariepy, Genevieve; Leach, Jonathan; Kim, Kyung Taec; Hammond, T. J.; Frumker, E.; Boyd, Robert W.; Corkum, P. B.

    2014-10-01

    A beam with an angular-dependant phase Φ =ℓϕ about the beam axis carries an orbital angular momentum of ℓℏ per photon. Such beams are exploited to provide superresolution in microscopy. Creating extreme ultraviolet or soft-x-ray beams with controllable orbital angular momentum is a critical step towards extending superresolution to much higher spatial resolution. We show that orbital angular momentum is conserved during high-harmonic generation. Experimentally, we use a fundamental beam with |ℓ|=1 and interferometrically determine that the harmonics each have orbital angular momentum equal to their harmonic number. Theoretically, we show how any small value of orbital angular momentum can be coupled to any harmonic in a controlled manner. Our results open a route to microscopy on the molecular, or even submolecular, scale.

  12. Stochastic orbit loss of neutral beam ions from NSTX due to toroidal Alfvén eigenmode avalanches

    SciTech Connect

    Darrow, D. S.; Crocker, N.; Fredrickson, E. D.; Gorelenkov, N. N.; Gorelenkova, M.; Kubota, S.; Medley, S. S.; Podestà, M.; Shi, L.; White, R. B.

    2012-12-17

    Short toroidal Alfvén eigenmode (TAE) avalanche bursts in the National Spherical Torus Experiment (NSTX) cause a drop in the neutron rate and could also cause a loss of neutral beam ions at or near the full injection energy over an extended range of pitch angles. The simultaneous loss of wide ranges of pitch angle suggests stochastic transport of the beam ions takes place. When beam ion orbits are followed with a guiding centre code that incorporates the plasma's magnetic equilibrium plus the measured modes, the predicted ranges of lost pitch angle are like those seen in the experiment, with distinct populations of trapped and passing orbits lost. These correspond to domains where the stochasticity extends in the orbit phase space from the region of beam ion deposition to the loss boundary and the trajectories along which modes may transport particles extend from the deposition volume to the loss boundary.

  13. Smart beam shape control using shape memory alloys

    NASA Astrophysics Data System (ADS)

    Maari, Sami Mikhail

    The thermoelastic martensitic transformation of Nitinol was utilized to control the shape of a metal beam. Nitinol strips were bonded at an inclination angle on the surface of a beam to produce both bending and torsion. The Nitinol strips were thermally trained to provide the shape memory effect upon heating above the austenite start temperature. A set of differential equations describing beam equilibrium conditions during the heating of the Nitinol strips to a temperature in the martensite-austenite domain were developed. This set of equations was solved numerically using a finite difference method. The solution provided the beam strain distribution as a function of Nitinol temperature and the spatial coordinate along the beam neutral axis. The beam neutral axis slope and twist were then calculated form the strain distribution of the beam. The displacement and twist for beams with multiple strips were computed by superimposing the solutions for individual Nitinol strips. The predictions of the mathematical model were used to generate the solution for several benchmark problems of a cantilevered beam with different arrangements and volume fractions of Nitinol strips. The results were compared with those for the comparable experimental configuration.

  14. Performance and Controllability of Pulsed Ion Beam Ablation Propulsion

    SciTech Connect

    Yazawa, Masaru; Buttapeng, Chainarong; Harada, Nobuhiro; Suematsu, Hisayuki; Jiang Weihua; Yatsui, Kiyoshi

    2006-05-02

    We propose novel propulsion driven by ablation plasma pressures produced by the irradiation of pulsed ion beams onto a propellant. The ion beam ablation propulsion demonstrates by a thin foil (50 {mu}mt), and the flyer velocity of 7.7 km/s at the ion beam energy density of 2 kJ/cm2 adopted by using the Time-of-flight method is observed numerically and experimentally. We estimate the performance of the ion beam ablation propulsion as specific impulse of 3600 s and impulse bit density of 1700 Ns/m2 obtained from the demonstration results. In the numerical analysis, a one-dimensional hydrodynamic model with ion beam energy depositions is used. The control of the ion beam kinetic energy is only improvement of the performance but also propellant consumption. The spacecraft driven by the ion beam ablation provides high performance efficiency with short-pulsed ion beam irradiation. The numerical results of the advanced model explained latent heat and real gas equation of state agreed well with experimental ones over a wide range of the incident ion beam energy density.

  15. Loss of beam ions to the inside of the PDX (Poloidal Divertor Experiment) tokamak during the fishbone instability

    SciTech Connect

    Heidbrink, W.W.; Beiersdorfer, P.

    1986-11-01

    Using data from two vertical charge-exchange detectors on the Poloidal Divertor Experiment (PDX), we have identified a set of conditions for which loss of beam ions inward in major radius is observed during the fishbone instability. Previously, it was reported that beam ions were lost only to the outside of the PDX tokamak.

  16. Aircraft Loss of Control Causal Factors and Mitigation Challenges

    NASA Technical Reports Server (NTRS)

    Jacobson, Steven R.

    2010-01-01

    Loss of control is the leading cause of jet fatalities worldwide. Aside from their frequency of occurrence, accidents resulting from loss of aircraft control seize the public s attention by yielding a large number of fatalities in a single event. In response to the rising threat to aviation safety, the NASA Aviation Safety Program has conducted a study of the loss of control problem. This study gathered four types of information pertaining to loss of control accidents: (1) statistical data; (2) individual accident reports that cite loss of control as a contributing factor; (3) previous meta-analyses of loss of control accidents; and (4) inputs solicited from aircraft manufacturers, air carriers, researchers, and other industry stakeholders. Using these information resources, the study team identified the causal factors that were cited in the greatest number of loss of control accidents, and which were emphasized most by industry stakeholders. This report describes the study approach, the key causal factors for aircraft loss of control, and recommended mitigation strategies to make near-term impacts, mid-term impacts, and Next Generation Air Transportation System impacts on the loss of control accident statistics

  17. Longitudinal Control of Intense Charged Particle Beams

    DTIC Science & Technology

    2011-01-01

    contained using longitudinal focusing, I have shown that errors in the applied focusing fields induce space-charge waves at the bunch edges that...profile along the bunch length. When the bunch is contained using longitudinal focusing, I have shown that errors in the applied focusing fields ...90 5.1.1 Beam Expansion without Longitudinal Containment................................ 90 5.1.2 Application of Focusing Fields

  18. High performance quantum cascade lasers: Loss, beam stability, and gain engineering

    NASA Astrophysics Data System (ADS)

    Bouzi, Pierre Michel

    Quantum Cascade (QC) lasers are semiconductor devices emitting in the mid-infrared (3-30 micron) and terahertz (30-300 micron) regions of the electromagnetic spectrum. Since their first demonstration by Jerome Faist et. al. in 1994, they have evolved very quickly into high performance devices and given rise to many applications such as trace-gas sensing, medical diagnosis, free-space communication, and light detection and ranging (LIDAR). In this thesis, we investigate a further increase of the performance of QC devices and, through meticulous device modeling and characterizations, gain a deeper understanding of several of their unique characteristics, especially their carrier transport and lifetime, their characteristic temperature, their waveguide loss and modal gain, their leakage current, and their transverse mode profile. First, in our quest to achieve higher performance, we investigate the effect of growth asymmetries on device transport characteristics. This investigation stems from recent studies on the role of interface roughness on intersubband scattering and device performance. Through a symmetric active core design, we find that interface roughness and ionized impurity scattering induced by dopant migration play a significant role in carrier transport through the device. Understanding how interface roughness affects intersubband scattering, in turn, we engineer the gain in QC devices by placing monolayer barriers at specific locations within the device band structure. These strategically placed additional thin barrier layers introduce roughness scattering into the device active region, thereby selectively decreasing the lower laser state lifetime and increasing population inversion necessary for laser action. Preliminary measurement results from modified devices reveal a 50% decrease in the emission broadening compared to the control structures, which should lead to a two-fold increase in gain. A special class of so-called "strong coupling" QC lasers

  19. Analysis and modeling of proton beam loss and emittance growth in the Relativistic Heavy Ion Collider

    DOE PAGES

    Luo, Y.; Fischer, W.; White, S.

    2016-02-04

    The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory has been operating since 2000. Over the past decade, thanks to the continuously increased bunch intensity and reduced β*s at the interaction points, the peak luminosity in the polarized proton operation has been increased by more than two orders of magnitude. In this article, we will present the operational observations at the routine proton physics stores. In addition, the mechanisms for the beam loss, transverse emittance growth, and bunch lengthening are analyzed. Lastly, numerical calculations and multiparticle tracking are used to model these observations.

  20. Dynamic control of collapse in a vortex Airy beam.

    PubMed

    Chen, Rui-Pin; Chew, Khian-Hooi; He, Sailing

    2013-01-01

    Here we study systematically the self-focusing dynamics and collapse of vortex Airy optical beams in a Kerr medium. The collapse is suppressed compared to a non-vortex Airy beam in a Kerr medium due to the existence of vortex fields. The locations of collapse depend sensitively on the initial power, vortex order, and modulation parameters. The collapse may occur in a position where the initial field is nearly zero, while no collapse appears in the region where the initial field is mainly distributed. Compared with a non-vortex Airy beam, the collapse of a vortex Airy beam can occur at a position away from the area of the initial field distribution. Our study shows the possibility of controlling and manipulating the collapse, especially the precise position of collapse, by purposely choosing appropriate initial power, vortex order or modulation parameters of a vortex Airy beam.

  1. Dynamic Control of Collapse in a Vortex Airy Beam

    PubMed Central

    Chen, Rui-Pin; Chew, Khian-Hooi; He, Sailing

    2013-01-01

    Here we study systematically the self-focusing dynamics and collapse of vortex Airy optical beams in a Kerr medium. The collapse is suppressed compared to a non-vortex Airy beam in a Kerr medium due to the existence of vortex fields. The locations of collapse depend sensitively on the initial power, vortex order, and modulation parameters. The collapse may occur in a position where the initial field is nearly zero, while no collapse appears in the region where the initial field is mainly distributed. Compared with a non-vortex Airy beam, the collapse of a vortex Airy beam can occur at a position away from the area of the initial field distribution. Our study shows the possibility of controlling and manipulating the collapse, especially the precise position of collapse, by purposely choosing appropriate initial power, vortex order or modulation parameters of a vortex Airy beam. PMID:23518858

  2. TANGO standard software to control the Nuclotron beam slow extraction

    NASA Astrophysics Data System (ADS)

    Andreev, V. A.; Volkov, V. I.; Gorbachev, E. V.; Isadov, V. A.; Kirichenko, A. E.; Romanov, S. V.; Sedykh, G. S.

    2016-09-01

    TANGO Controls is a basis of the NICA control system. The report describes the software which integrates the Nuclotron beam slow extraction subsystem into the TANGO system of NICA. Objects of control are power supplies for resonance lenses. The software consists of the subsystem device server, remote client and web-module for viewing the subsystem data.

  3. Acrylamide/acrylic acid copolymers for cement fluid loss control

    SciTech Connect

    McKenzie, L.F.; McElfresh, P.M.

    1982-01-01

    Acrylamide/acrylic acid copolymers are considered as effective fluid loss control additives in a wide range of oil well cements. Unlike HEC based fluid loss aditives, these copolymers can be used with calcium chloride accelerator without significantly influencing fluid loss control. Another advantage of the copolymers is that the amount of fluid loss for a given concentration of polymer remains relatively constant over a wide range of temperatures. The use of acrylamide/acrylic acid copolymers has generally been restricted to wells below 60 degree C BHCT. Above that temperature chemical changes in the copolymer often lead to retardation of the cement. This paper presents data related to the use of acrylamide/acrylic acid copolymers as fluid loss control agents in oil well cementing. A comparison of these polymers with HEC based fluid loss control additives is made. In addition, data related to the cause of acrylamide/acrylic acid copolymer retarding effects is presented. 4 refs.

  4. A general algorithm for calculation of recombination losses in ionization chambers exposed to ion beams.

    PubMed

    Christensen, Jeppe Brage; Tölli, Heikki; Bassler, Niels

    2016-10-01

    Dosimetry with ionization chambers in clinical ion beams for radiation therapy requires correction for recombination effects. However, common radiation protocols discriminate between initial and general recombination and provide no universal correction method for the presence of both recombination types in ion beams of charged particles heavier than protons. The advent of multiple field optimization in ion beams, allowing for complex patterns of dose delivery in both temporal and spatial domains, results in new challenges for recombination correction where the resulting recombination depends on the plan delivered. Here, the authors present the open source code IonTracks version 1.0, where the combined initial and general recombination effects in principle can be predicted for any ion beam with arbitrary particle-energy spectrum and temporal structure. IonTracks uses track structure theory to distribute the charge carriers in ion tracks. The charge carrier movements are governed by a pair of coupled differential equations, based on fundamental physical properties as charge carrier drift, diffusion, and recombination, which are solved numerically while the initial and general charge carrier recombination is computed. A space charge screening of the electric field is taken into account and the algorithm furthermore allows an inclusion of a free-electron component. The algorithm is numerically stable and in accordance with experimentally validated theories for initial recombination in heavy ion tracks and general recombination in a proton beam. Given IonTracks' ability to handle arbitrary inputs, IonTracks can in principle be applied to any complex particle field in the spatial and temporal domain. IonTracks is validated against the Jaffé's and Boag's theory of recombination in pulsed beams of multiple ion species. IonTracks is able to calculate the correction factor for initial and general recombination losses in parallel-plate ionization chambers. Even if only few

  5. Prompt Loss of Energetic Ions during Early Neutral Beam Injection in the National Spherical Torus Experiment

    SciTech Connect

    S.S. Medley; D.S. Darrow; D. Liu; A.L. Roquemore

    2005-03-25

    Early neutral-beam injection is used in the National Spherical Torus Experiment (NSTX) to heat the electrons and slow current penetration which keeps q(0) elevated to avoid deleterious MHD activity and at the same time reduces Ohmic flux consumption, all of which aids long-pulse operation. However, the low plasma current (I{sub p} {approx} 0.5 MA) and electron density (n{sub e} {approx} 1 x 10{sup 13} cm{sup -3}) attending early injection lead to elevated orbit and shine through losses. The inherent orbit losses are aggravated by large excursions in the outer gap width during current ramp-up. An investigation of this behavior using various energetic particle diagnostics on NSTX and TRANSP code analysis is presented.

  6. Networked Robust Predictive Control Systems Design with Packet Loss

    NASA Astrophysics Data System (ADS)

    Nguyen, Quang T.; Veselý, Vojtech; Kozáková, Alena; Pakshin, Pavel

    2014-01-01

    The paper addresses problem of designing a robust output feedback model predictive control for uncertain linear systems over networks with packet-loss. The packet-loss process is arbitrary and bounded by the control horizon of model predictive control. Networked predictive control systems with packet loss are modeled as switched linear systems. This enables us to apply the theory of switched systems to establish the stability condition. The stabilizing controller design is based on sufficient robust stability conditions formulated as a solution of bilinear matrix inequality. Finally, a benchmark numerical example-double integrator is given to illustrate the effectiveness of the proposed method.

  7. Aircraft Accident Prevention: Loss-of-Control Analysis

    NASA Technical Reports Server (NTRS)

    Kwatny, Harry G.; Dongmo, Jean-Etienne T.; Chang, Bor-Chin; Bajpai, Guarav; Yasar, Murat; Belcastro, Christine M.

    2009-01-01

    The majority of fatal aircraft accidents are associated with loss-of-control . Yet the notion of loss-of-control is not well-defined in terms suitable for rigorous control systems analysis. Loss-of-control is generally associated with flight outside of the normal flight envelope, with nonlinear influences, and with an inability of the pilot to control the aircraft. The two primary sources of nonlinearity are the intrinsic nonlinear dynamics of the aircraft and the state and control constraints within which the aircraft must operate. In this paper we examine how these nonlinearities affect the ability to control the aircraft and how they may contribute to loss-of-control. Examples are provided using NASA s Generic Transport Model.

  8. Calibration of Fast Fiber-Optic Beam Loss Monitors for the Advanced Photon Source Storage Ring Superconducting Undulators

    SciTech Connect

    Dooling, J.; Harkay, K.; Ivanyushenkov, Y.; Sajaev, V.; Xiao, A.; Vella, Andrea K.

    2015-01-01

    We report on the calibration and use of fast fiber-optic (FO) beam loss monitors (BLMs) in the Advanced Photon Source storage ring (SR). A superconducting undulator prototype (SCU0) has been operating in SR Sector 6 (“ID6”) since the beginning of CY2013, and another undulator SCU1 (a 1.1-m length undulator that is three times the length of SCU0) is scheduled for installation in Sector 1 (“ID1”) in 2015. The SCU0 main coil often quenches during beam dumps. MARS simulations have shown that relatively small beam loss (<1 nC) can lead to temperature excursions sufficient to cause quenchingwhen the SCU0windings are near critical current. To characterize local beam losses, high-purity fused-silica FO cables were installed in ID6 on the SCU0 chamber transitions and in ID1 where SCU1 will be installed. These BLMs aid in the search for operating modes that protect the SCU structures from beam-loss-induced quenching. In this paper, we describe the BLM calibration process that included deliberate beam dumps at locations of BLMs. We also compare beam dump events where SCU0 did and did not quench.

  9. Stochastic boundary control design for Timoshenko beams with large motions

    NASA Astrophysics Data System (ADS)

    Do, K. D.

    2017-08-01

    This paper considers modeling and boundary control of Timoshenko beams with large motions under both deterministic and stochastic external loads. The original nonlinear partial differential equations governing motion of the beams are derived and used in the control design. The control design is based on the Lyapunov direct method. The proposed controllers guarantee globally practically K∞-exponentially p-stability of the beam motions at the reference state. Well-posedness and stability are analyzed based on a Lyapunov-type theorem developed to study well-posedness and stability for a class of stochastic evolution systems in Hilbert space. Simulation results are included to illustrate the effectiveness of the proposed control design.

  10. Continuous beam divergence control via wedge-pair for laser communication applications

    NASA Astrophysics Data System (ADS)

    Hinrichs, Keith M.; DeCew, Alan E.; Narkewich, Lawrence E.; Williams, Timothy H.

    2015-03-01

    Lasercom terminals often scan an area of uncertainty during acquisition with a wide-divergence beacon beam. Once the terminal has established cooperative tracking with the remote terminal, a narrow divergence beam is used for communication. A mechanism that enables continuous beam divergence control can provide significant size, weight, and power (SWaP) benefits to the terminal. First, the acquisition and the communication beams can be launched from the same fiber so only a single high-power optical amplifier is required. Second, by providing mid-divergences, it eases the remote terminal's transition from the acquisition phase to the communication phase. This paper describes a mechanism that provides gradual, progressive adjustment of far-field beam divergence, from wide divergence (> 300 μrad FWHM) through collimated condition (38 μrad FWHM) and that works over a range of wavelengths. The mechanism is comprised of a variable-thickness optical element, formed by a pair of opposing wedges that is placed between the launch fiber and the collimating lens. Variations in divergence with no beam blockage are created by laterally translating one wedge relative to a fixed wedge. Divergence is continuously adjustable within the thickness range, allowing for a coordinated transition of divergence, wavelength, and beam power. Measurements of this low-loss, low-wavefront error assembly show that boresight error during divergence transition is maintained to a fraction of the communication beamwidth over wavelength and optical power ranges.

  11. Runaway electron beam control for longitudinally pumped metal vapor lasers

    NASA Astrophysics Data System (ADS)

    Kolbychev, G. V.; Kolbycheva, P. D.

    1995-08-01

    Physics and techniques for producing of the pulsed runaway electron beams are considered. The main obstacle for increasing electron energies in the beams is revealed to be a self- breakdown of the e-gun's gas-filled diode. Two methods to suppress the self-breakdown and enhance the volumetric discharge producing the e-beam are offered and examined. Each of them provides 1.5 fold increase of the ceiling potential on the gun. The methods also give the ways to control several guns simultaneously. Resulting in the possibility of realizing the powerful longitudinal pumping of metal-vapor lasers on self-terminated transitions of atoms or ions.

  12. Experimental identification and control of a flexible beam

    NASA Astrophysics Data System (ADS)

    Krishnan, Ram S.; Mote, C. D.; Tomizuka, M.

    1992-01-01

    Experimental parameter identification and tip position control of a flexible beam attached at one end to a motor shaft are discussed in this paper. Modelling and identification experiments, including discussion of sampling-time and input amplitude selection and a unique displacement sensor for measuring the tip-position are considered first. Then tip-position control using optimal control (Linear Quadratic) and "preview" control methods are demonstrated. Position control performances with and without tip position feedback are compared.

  13. Electron beams and loss cones in the auroral regions of Jupiter

    NASA Astrophysics Data System (ADS)

    Allegrini, F.; Bagenal, F.; Bolton, S.; Connerney, J.; Clark, G.; Ebert, R. W.; Kim, T. K.; Kurth, W. S.; Levin, S.; Louarn, P.; Mauk, B.; McComas, D. J.; Pollock, C.; Ranquist, D.; Reno, M.; Szalay, J. R.; Thomsen, M. F.; Valek, P.; Weidner, S.; Wilson, R. J.; Zink, J. L.

    2017-07-01

    We report on the first observations of 100 eV to 100 keV electrons over the auroral regions of Jupiter by the Jovian Auroral Distributions Experiment (JADE) on board the Juno mission. The focus is on the regions that were magnetically connected to the main auroral oval. Amongst the most remarkable features, JADE observed electron beams, mostly upward going but also some downward going in the south, at latitudes from 69° to 72° and -66° to -70° corresponding to M shells ("M" for magnetic) from 18 to 54 and 28 to 61, respectively. The beams were replaced by upward loss cones at lower latitudes. There was no evidence of strongly accelerated downward electrons analogous to the auroral "inverted Vs" at Earth. Rather, the presence of upward loss cones suggests a diffuse aurora process. The energy spectra resemble tails of distributions or power laws (suggestive of a stochastic acceleration process) but can also have some clear enhancements or even peaks generally between 1 and 10 keV. Electron intensities change on timescales of a second or less at times implying that auroral structures can be of the order of a few tens of kilometers.

  14. Energy loss of proton, alpha particle, and electron beams in hafnium dioxide films

    SciTech Connect

    Behar, Moni; Fadanelli, Raul C.; Nagamine, Luiz C. C. M.; Abril, Isabel; Denton, Cristian D.; Garcia-Molina, Rafael; Arista, Nestor R.

    2009-12-15

    The electronic stopping power, S, of HfO{sub 2} films for proton and alpha particle beams has been measured and calculated. The experimental data have been obtained by the Rutherford backscattering technique and cover the range of 120-900 and 120-3000 keV for proton and alpha particle beams, respectively. Theoretical calculations of the energy loss for the same projectiles have been done by means of the dielectric formalism using the Mermin energy loss function--generalized oscillator strength (MELF-GOS) model for a proper description of the HfO{sub 2} target on the whole momentum-energy excitation spectrum. At low projectile energies, a nonlinear theory based on the extended Friedel sum rule has been employed. The calculations and experimental measurements show good agreement for protons and a quite good one for alpha particles. In particular, the experimental maximums of both stopping curves (around 120 and 800 keV, respectively) are well reproduced. On the basis of this good agreement, we have also calculated the inelastic mean-free path (IMFP) and the stopping power for electrons in HfO{sub 2} films. Our results predict a minimum value of the IMFP and a maximum value of the S for electrons with energies around 120 and 190 eV, respectively.

  15. Optimal vibration control of curved beams using distributed parameter models

    NASA Astrophysics Data System (ADS)

    Liu, Fushou; Jin, Dongping; Wen, Hao

    2016-12-01

    The design of linear quadratic optimal controller using spectral factorization method is studied for vibration suppression of curved beam structures modeled as distributed parameter models. The equations of motion for active control of the in-plane vibration of a curved beam are developed firstly considering its shear deformation and rotary inertia, and then the state space model of the curved beam is established directly using the partial differential equations of motion. The functional gains for the distributed parameter model of curved beam are calculated by extending the spectral factorization method. Moreover, the response of the closed-loop control system is derived explicitly in frequency domain. Finally, the suppression of the vibration at the free end of a cantilevered curved beam by point control moment is studied through numerical case studies, in which the benefit of the presented method is shown by comparison with a constant gain velocity feedback control law, and the performance of the presented method on avoidance of control spillover is demonstrated.

  16. Control of a flexible beam using fuzzy logic

    NASA Technical Reports Server (NTRS)

    Mccullough, Claire L.

    1991-01-01

    The goal of this project, funded under the NASA Summer Faculty Fellowship program, was to evaluate control methods utilizing fuzzy logic for applicability to control of flexible structures. This was done by applying these methods to control of the Control Structures Interaction Suitcase Demonstrator developed at Marshall Space Flight Center. The CSI Suitcase Demonstrator is a flexible beam, mounted at one end with springs and bearing, and with a single actuator capable of rotating the beam about a pin at the fixed end. The control objective is to return the tip of the free end to a zero error position (from a nonzero initial condition). It is neither completely controllable nor completely observable. Fuzzy logic control was demonstrated to successfully control the system and to exhibit desirable robustness properties compared to conventional control.

  17. Electron Beam Technology for Environmental Pollution Control.

    PubMed

    Chmielewski, Andrzej G; Han, Bumsoo

    2016-10-01

    Worldwide, there are over 1700 electron beam (EB) units in commercial use, providing an estimated added value to numerous products, amounting to 100 billion USD or more. High-current electron accelerators are used in diverse industries to enhance the physical and chemical properties of materials and to reduce undesirable contaminants such as pathogens, toxic byproducts, or emissions. Over the past few decades, EB technologies have been developed aimed at ensuring the safety of gaseous and liquid effluents discharged to the environment. It has been demonstrated that EB technologies for flue gas treatment (SO x and NO x removal), wastewater purification, and sludge hygienization can be effectively deployed to mitigate environmental degradation. Recently, extensive work has been carried out on the use of EB for environmental remediation, which also includes the removal of emerging contaminants such as VOCs, endocrine disrupting chemicals (EDCs), and potential EDCs.

  18. Controllable light capsules employing modified Bessel-Gauss beams

    PubMed Central

    Gong, Lei; Liu, Weiwei; Zhao, Qian; Ren, Yuxuan; Qiu, Xingze; Zhong, Mincheng; Li, Yinmei

    2016-01-01

    We report, in theory and experiment, on a novel class of controlled light capsules with nearly perfect darkness, directly employing intrinsic properties of modified Bessel-Gauss beams. These beams are able to naturally create three-dimensional bottle-shaped region during propagation as long as the parameters are properly chosen. Remarkably, the optical bottle can be controlled to demonstrate various geometries through tuning the beam parameters, thereby leading to an adjustable light capsule. We provide a detailed insight into the theoretical origin and characteristics of the light capsule derived from modified Bessel-Gauss beams. Moreover, a binary digital micromirror device (DMD) based scheme is first employed to shape the bottle beams by precise amplitude and phase manipulation. Further, we demonstrate their ability for optical trapping of core-shell magnetic microparticles, which play a particular role in biomedical research, with holographic optical tweezers. Therefore, our observations provide a new route for generating and controlling bottle beams and will widen the potentials for micromanipulation of absorbing particles, aerosols or even individual atoms. PMID:27388558

  19. Controllable light capsules employing modified Bessel-Gauss beams

    NASA Astrophysics Data System (ADS)

    Gong, Lei; Liu, Weiwei; Zhao, Qian; Ren, Yuxuan; Qiu, Xingze; Zhong, Mincheng; Li, Yinmei

    2016-07-01

    We report, in theory and experiment, on a novel class of controlled light capsules with nearly perfect darkness, directly employing intrinsic properties of modified Bessel-Gauss beams. These beams are able to naturally create three-dimensional bottle-shaped region during propagation as long as the parameters are properly chosen. Remarkably, the optical bottle can be controlled to demonstrate various geometries through tuning the beam parameters, thereby leading to an adjustable light capsule. We provide a detailed insight into the theoretical origin and characteristics of the light capsule derived from modified Bessel-Gauss beams. Moreover, a binary digital micromirror device (DMD) based scheme is first employed to shape the bottle beams by precise amplitude and phase manipulation. Further, we demonstrate their ability for optical trapping of core-shell magnetic microparticles, which play a particular role in biomedical research, with holographic optical tweezers. Therefore, our observations provide a new route for generating and controlling bottle beams and will widen the potentials for micromanipulation of absorbing particles, aerosols or even individual atoms.

  20. Controllable light capsules employing modified Bessel-Gauss beams.

    PubMed

    Gong, Lei; Liu, Weiwei; Zhao, Qian; Ren, Yuxuan; Qiu, Xingze; Zhong, Mincheng; Li, Yinmei

    2016-07-08

    We report, in theory and experiment, on a novel class of controlled light capsules with nearly perfect darkness, directly employing intrinsic properties of modified Bessel-Gauss beams. These beams are able to naturally create three-dimensional bottle-shaped region during propagation as long as the parameters are properly chosen. Remarkably, the optical bottle can be controlled to demonstrate various geometries through tuning the beam parameters, thereby leading to an adjustable light capsule. We provide a detailed insight into the theoretical origin and characteristics of the light capsule derived from modified Bessel-Gauss beams. Moreover, a binary digital micromirror device (DMD) based scheme is first employed to shape the bottle beams by precise amplitude and phase manipulation. Further, we demonstrate their ability for optical trapping of core-shell magnetic microparticles, which play a particular role in biomedical research, with holographic optical tweezers. Therefore, our observations provide a new route for generating and controlling bottle beams and will widen the potentials for micromanipulation of absorbing particles, aerosols or even individual atoms.

  1. Shielding NSLS-II light source: Importance of geometry for calculating radiation levels from beam losses [Shielding Synchrotron Light Sources: Importance of geometry for calculating radiation levels from beam losses

    SciTech Connect

    Kramer, S. L.; Ghosh, V. J.; Breitfeller, M.; Wahl, W.

    2016-08-10

    Third generation high brightness light sources are designed to have low emittance and high current beams, which contribute to higher beam loss rates that will be compensated by Top-Off injection. Shielding for these higher loss rates will be critical to protect the projected higher occupancy factors for the users. Top-Off injection requires a full energy injector, which will demand greater consideration of the potential abnormal beam miss-steering and localized losses that could occur. The high energy electron injection beam produces significantly higher neutron component dose to the experimental floor than a lower energy beam injection and ramped operations. Minimizing this dose will require adequate knowledge of where the miss-steered beam can occur and sufficient EM shielding close to the loss point, in order to attenuate the energy of the particles in the EM shower below the neutron production threshold (<10 MeV), which will spread the incident energy on the bulk shield walls and thereby the dose penetrating the shield walls. Designing supplemental shielding near the loss point using the analytic shielding model is shown to be inadequate because of its lack of geometry specification for the EM shower process. To predict the dose rates outside the tunnel requires detailed description of the geometry and materials that the beam losses will encounter inside the tunnel. Modern radiation shielding Monte-Carlo codes, like FLUKA, can handle this geometric description of the radiation transport process in sufficient detail, allowing accurate predictions of the dose rates expected and the ability to show weaknesses in the design before a high radiation incident occurs. The effort required to adequately define the accelerator geometry for these codes has been greatly reduced with the implementation of the graphical interface of FLAIR to FLUKA. This made the effective shielding process for NSLS-II quite accurate and reliable. Lastly, the principles used to provide

  2. GENERATION AND CONTROL OF HIGH PRECISION BEAMS AT LEPTON ACCELERATORS

    SciTech Connect

    Yu-Chiu Chao

    2007-06-25

    Parity violation experiments require precision manipulation of helicity-correlated beam coordinates on target at the nm/nrad-level. Achieving this unprecedented level of control requires a detailed understanding of the particle optics and careful tuning of the beam transport to keep anomalies from compromising the design adiabatic damping. Such efforts are often hindered by machine configuration and instrumentation limitations at the low energy end. A technique has been developed at CEBAF including high precision measurements, Mathematica-based analysis for obtaining corrective solutions, and control hardware/software developments for realizing such level of control at energies up to 5 GeV.

  3. Control of Space-Based Electron Beam Free Form Fabrication

    NASA Technical Reports Server (NTRS)

    Seifzer. W. J.; Taminger, K. M.

    2007-01-01

    Engineering a closed-loop control system for an electron beam welder for space-based additive manufacturing is challenging. For earth and space based applications, components must work in a vacuum and optical components become occluded with metal vapor deposition. For extraterrestrial applications added components increase launch weight, increase complexity, and increase space flight certification efforts. Here we present a software tool that closely couples path planning and E-beam parameter controls into the build process to increase flexibility. In an environment where data collection hinders real-time control, another approach is considered that will still yield a high quality build.

  4. The control system for the LEP beam dump

    NASA Astrophysics Data System (ADS)

    Carlier, E.; Aimar, A.; Bretin, J. L.; Marchand, A.; Mertens, V.; Verhagen, H.

    1994-12-01

    A beam abort system has been developed and installed in LEP to allow the controlled disposal of the stored beam energy. In view of the importance of the system for the protection of the experiments and the machine, and the technical problems in a pulsed high-power environment, special care has been taken to arrive at a clean functional separation between the different elements of the control electronics, using optical transmission of information. All interlocks have been implemented in hardware. The slow controls and the monitoring tasks have been realized in the framework of a modular software tool kit.

  5. VERTICAL BEAM SIZE CONTROL IN TLS AND TPS.

    SciTech Connect

    KUO, C.C.; CHEN, J.R.; CHOU, P.J.; CHANG, H.P.; HSU, K.T.; LUO, G.H.; TSAI, H.J.; WANG, D.J.; WANG, M.H.

    2006-06-26

    Vertical beam size control is an important issue in the light source operations. The horizontal-vertical betatron coupling and vertical dispersion were measured and corrected to small values in the TLS 1.5 GeV storage ring. Estimated beam sizes are compared with the measured values. By employing an effective transverse damping system, the vertical beam blow-up due to transverse coherent instabilities, such as the fast-ion beam instability, was suppressed. As a result, the light source is very stable. In NSRRC we are designing an ultra low emittance 3-GeV storage ring and its designed vertical beam size could be as small as a few microns. The ground and mechanic vibration effects, and coherent instabilities could spoil the expected photon brightness due to blow-up of the vertical beam size if not well taken care of. The contributions of these effects to vertical beam size increase will be evaluated and the counter measures to minimize them will be proposed and reported in this paper.

  6. Optimal Control of the Starfire Beam Director

    DTIC Science & Technology

    1992-12-01

    amplifier has built-in proportional plus integral ( PI ) control circuitry for the purpose of rejecting the back EMF. Since measured closed-loop amplifier...throughout a satellite pass. PI control yields zero steady state error to a step input. At worse case the commanded position input has a small...designed in a classical sense in that it consists of PI control and a lead, where high gain and the lead are required to achieve the necessary bandwidth

  7. Ribbon Ion Beam with Controlled Directionality and Local Reactive Chemistry

    NASA Astrophysics Data System (ADS)

    Biloiu, Costel; Gilchrist, Glen; Kontos, Alex; Basame, Solomon; Rockwell, Tyler; Campbell, Chris; Daniels, Kevin; Allen, Ernest; Wallace, Jay; Ballou, Jon; Hertel, Richard; Chen, Tsung-Liang; Liang, Shurong; Singh, Vikram

    2016-09-01

    A plasma processing technology designed for etch of 3D semiconductor structures is presented. The technology is characterized by controllable ion directionality and local reactive chemistry and it is based on proprietary Applied Materials - Varian Semiconductor Equipment ribbon ion beam architecture. It uses a combination of inert gas ion beam and injection of reactive chemical species at the Point-of-Use (PoU), i.e., at the wafer surface. The ion source uses an inductively coupled plasma source and a diode-type extraction optics. A beam shaping electrode allows extraction of two symmetrical ribbon-like beamlets. The ion beam has in situ controllable ion angular distribution in both mean angle and angular spread. The beam has a uniform distribution of beam current and angles over a waist exceeding 300 mm, allowing full wafer processing in one pass. Chemical compounds are delivered at PoU through linear shower heads. The reactive chemical compound delivered in this fashion maintains its molecular integrity. This result in protection of the trench side walls from deposition of etch residue and facilitates formation of volatile byproducts. The technology was used successfully for mitigation of Magnetic Tunel Junction etch residue. Other applications were this technology differentiate from present technologies are contact liner etch, Co recess, and 1D hole elongation.

  8. Bandgap control using strained beam structures for Si photonic devices.

    PubMed

    Yoshimoto, Kohei; Suzuki, Ryota; Ishikawa, Yasuhiko; Wada, Kazumi

    2010-12-06

    We have demonstrated that bandgap energy of Si can be controlled by micro-mechanically structured Si beams (250 nm thick, 3 μm wide, and 15 μm long) elastically deformed by an external force. Microscopic photoluminescence spectroscopy reveals that downward bending of the beam by 3 μm reveals a red shift in the peak from ~1100 nm up to ~1300 nm. It is found from calculations based on deformation potentials and finite element method that tensile strain as large as ~1.5% is generated in the top surface of the deformed beam and responsible for the red shift of the peak. The presented result should be a proof of concept to cancel wavelength fluctuation unavoidably occurring on uncooled LSIs in terms of stress application, and thereby an enabler of wavelength division multiplexing implementation on a chip. The applications of other beam materials such as Ge and GaAs are discussed.

  9. Trapping volume control in optical tweezers using cylindrical vector beams.

    PubMed

    Skelton, S E; Sergides, M; Saija, R; Iatì, M A; Maragó, O M; Jones, P H

    2013-01-01

    We present the result of an investigation into the optical trapping of spherical microparticles using laser beams with a spatially inhomogeneous polarization direction [cylindrical vector beams (CVBs)]. We perform three-dimensional tracking of the Brownian fluctuations in the position of a trapped particle and extract the trap spring constants. We characterize the trap geometry by the aspect ratio of spring constants in the directions transverse and parallel to the beam propagation direction and evaluate this figure of merit as a function of polarization angle. We show that the additional degree of freedom present in CVBs allows us to control the optical trap strength and geometry by adjusting only the polarization of the trapping beam. Experimental results are compared with a theoretical model of optical trapping using CVBs derived from electromagnetic scattering theory in the T-matrix framework.

  10. Plasmonic beaming and active control over fluorescent emission.

    PubMed

    Jun, Young Chul; Huang, Kevin C Y; Brongersma, Mark L

    2011-01-01

    Nanometallic optical antennas are rapidly gaining popularity in applications that require exquisite control over light concentration and emission processes. The search is on for high-performance antennas that offer facile integration on chips. Here we demonstrate a new, easily fabricated optical antenna design that achieves an unprecedented level of control over fluorescent emission by combining concepts from plasmonics, radiative decay engineering and optical beaming. The antenna consists of a nanoscale plasmonic cavity filled with quantum dots coupled to a miniature grating structure that can be engineered to produce one or more highly collimated beams. Electromagnetic simulations and confocal microscopy were used to visualize the beaming process. The metals defining the plasmonic cavity can be utilized to electrically control the emission intensity and wavelength. These findings facilitate the realization of a new class of active optical antennas for use in new optical sources and a wide range of nanoscale optical spectroscopy applications.

  11. Control of an electrowetting-based beam deflector

    NASA Astrophysics Data System (ADS)

    de Boer, Bart; Suijver, Freek; Megens, Mischa; Deladi, Szabolcs; Kuiper, Stein

    2010-03-01

    We experimentally demonstrate the feasibility of a small, low-power beam deflector based on electrowetting. The beam deflector deflects light by refraction at the flat interface (meniscus) between two immiscible and density-matched liquids, namely, a nonpolar oil mixture and an aqueous salt solution. The liquids are contained in a square pyramidal frustum with electrode-covered faces. The electrodes can be separately driven by voltage sources in order to control the contact angle between the meniscus and the frustum faces. By controlling the voltage on all four electrodes, a flat meniscus is obtained that can be tilted independently in two perpendicular directions. We present a capacitance-based feedback driving scheme and demonstrate that it can be used for accurate control of the meniscus shape and tilt. Independent, continuous, and accurate beam steering through an angle of ±6° was achieved on two deflection axes.

  12. Improvement of electron beam shape control in radiation processing

    NASA Astrophysics Data System (ADS)

    Strasser, A.; Fang, R.; Kuntz, F.

    1994-05-01

    The development of radiation processing using electron accelerators requires good control of the treatment parameters to improve the dosimetry quality. Especially, the analysis of the shape of the scanned electron beam that interacts with the product, is of prime necessity. A Multiwire Beam Shape Analyser (MBSA) has been developed by the AERIAL Laboratory in order to insure good monitoring of the scanning length and uniformity. This device consists of an aluminum beam-stop covered with a mesh of individually insulated stainless steel wires, placed under the scanning cone. The current generated by the impact of the electron beam on each wire is converted into voltage. After pulse shaping and multiplexing of the different channels, the beam profile can be displayed on an oscilloscope or on a PC screen. A prototype is now operating on an experimental irradiation plant based on a 2.5 MeV /300 W Van de Graaff electron accelerator. It allows almost continuous visualization of the beam profile (between two conveyor passes) and its response was compared to classical film dosimeters (Gafchromic, FWT 60.00). Considering FWHM and homogeneous treatment regions of the profiles, MBSA and the dosimeters give similar responses and variations remain lower than ± 12%. The acquisition of an electrical signal corresponding to the beam profile in air constitutes the original aspect of the MBSA and is in keeping with the general pattern of continuous control and automation of the irradiation processes. Hereafter, much work has to be done to adapt this device to an industrial use (higher energy, high power electron beams, non-destructive measurements…).

  13. Fluid loss control differences of crosslinked and linear fracturing fluids

    SciTech Connect

    Zigrye, J.L.; Whitfill, D.L.; Sievert, J.A.

    1983-01-01

    Three fracturing fluids--a crosslinked guar, a delayed hydrating guar, and a linear guar--were tested for fluid loss control at set time intervals while being conditioned in a heated, pressurized flow loop. Each fluid was tested with 3 different fluid loss additive systems: diesel, silica flour, and a combination of diesel and silica flour. The crosslinked system was tested also with 2 additional fluid loss additive systems. These fluids were diesel plus an anionic surfactant and the combination of diesel/silica flour plus the anionic surfactant. These tests show that the fluid loss of crosslinked fracturing fluids is best controlled by using diesel in combination with a surfactant or a properly sized particulate material. The fluid loss of linear fluids is controlled best with particulate additives.

  14. Laser Beam Scanning For Remote Control

    NASA Astrophysics Data System (ADS)

    Neyroud, Jean; Metayer, Philippe; Danel, Francois

    1980-05-01

    The skiers access-control to skilifts requires to work unconstrainedly. Therefore, an optical remote control has been considered. A very low-power laser scanning allows to locate the user's skipass and read data barcodes printed on a reflective tag. Optical and electronical filters associated with a microcomputerized decoder allow informations reconstitution and the label validity checking. Each item of this product has been designed to aim the desired performances in the easiest and lowest-cost means.

  15. Engineering the Losses and Beam Divergence in Arrays of Patch Antenna Microcavities for Terahertz Sources

    NASA Astrophysics Data System (ADS)

    Madéo, Julien; Pérez-Urquizo, Joel; Todorov, Yanko; Sirtori, Carlo; Dani, Keshav M.

    2017-07-01

    We perform a comprehensive study on the emission from finite arrays of patch antenna microcavities designed for the terahertz range by using a finite element method. The emission properties including quality factors, far-field pattern, and photon extraction efficiency are investigated for etched and non-etched structures as a function of the number of resonators, the dielectric layer thickness, and period of the array. In addition, the simulations are achieved for lossy and perfect metals and dielectric layers, allowing to extract the radiative and non-radiative contributions to the total quality factors of the arrays. Our study shows that this structure can be optimized to obtain low beam divergence (FWHM <10°) and photon extraction efficiencies >50% while keeping a strongly localized mode. These results show that the use of these microcavities would lead to efficient terahertz emitters with a low divergence vertical emission and engineered losses.

  16. Retrograde amnesia produced by electron beam exposure: causal parameters and duration of memory loss. [Rats

    SciTech Connect

    Wheeler, T.G.; Hardy, K.A.

    1985-01-01

    The production of retrograde amnesia (RA) upon electron beam exposure has been investigated. RA production was evaluated using a single-trial avoidance task across a 10/sup 4/ dose range for 10-, 1-, and 0.1-..mu..sec pulsed exposures. The dose-response curve obtained at each pulse duration showed significant RA production. The most effective dose range was 0.1-10 rad at a dose rate of 10/sup 6/ rad/sec. By employing a 10 rad (10/sup 6/ rad/sec) pulse, a memory loss of the events occurring in the previous 4 sec was demonstrated. The conclusion was that the RA effect might be due to sensory activation which provided a novel stimulus that masked previous stimuli.

  17. Readout process and noise elimination firmware for the Fermilab beam loss system

    SciTech Connect

    Wu, Jinyuan; Baumbaugh, Alan; Drennan, Craig; Thurman-Keup, Randy; Lewis, Jonathan; Shi, Zonghan; /Fermilab

    2007-05-01

    In the Fermilab Beam Loss Monitor System, inputs from ion chambers are integrated for a short period of time, digitized and processed to create the accelerator abort request signals. The accelerator power supplies employing 3-phase 60Hz AC cause noise at various harmonics on our inputs which must be eliminated for monitoring purposes. During accelerator ramping, both the sampling frequency and the amplitudes of the noise components change. As such, traditional digital filtering can partially reduce certain noise components but not all. A nontraditional algorithm was developed in our work to eliminate remaining ripples. The sequencing in the FPGA firmware is conducted by a micro-sequencer core we developed: the Enclosed Loop Micro-Sequencer (ELMS). The unique feature of the ELMS is that it supports the ''FOR'' loops with pre-defined iterations at the machine code level, which provides programming convenience and avoids many micro-complexities from the beginning.

  18. Heart Failure and Loss of Metabolic Control

    PubMed Central

    Wang, Zhao V.; Li, Dan L.; Hill, Joseph A.

    2014-01-01

    Heart failure is a leading cause of morbidity and mortality worldwide, currently affecting 5 million Americans. A syndrome defined on clinical terms, heart failure is the end-result of events occurring in multiple heart diseases, including hypertension, myocardial infarction, genetic mutations and diabetes, and metabolic dysregulation is a hallmark feature. Mounting evidence from clinical and preclinical studies suggests strongly that fatty acid uptake and oxidation are adversely affected, especially in end-stage heart failure. Moreover, metabolic flexibility, the heart’s ability to move freely among diverse energy substrates, is impaired in heart failure. Indeed, impairment of the heart’s ability to adapt to its metabolic milieu, and associated metabolic derangement, are important contributing factors in heart failure pathogenesis. Elucidation of molecular mechanisms governing metabolic control in heart failure will provide critical insights into disease initiation and progression, raising the prospect of advances with clinical relevance. PMID:24336014

  19. Vibration control of flexible beams using an active hinge

    NASA Technical Reports Server (NTRS)

    Cudney, H. H., Jr.; Inman, D. J.; Horner, G. C.

    1985-01-01

    The use of an active hinge to attenuate the transverse vibrations of a flexible beam is examined. A slender aluminum beam is suspended vertically, cantilevered at the top. An active hinge is placed at the node of the second vibration mode. The active hinge consists of a torque motor, strain gauge, and tachometer. A control law is implemented using both beam-bending strain and the relative angular velocity measured at this hinge, thereby configuring the hinge to act as an active damper. Results from implementing this control law show little improvement in the first mode damping ratio, 130 percent increase in the second mode damping ratio, and 180 percent increase in the third mode damping ratio. The merits of using a motor with a gearbox are discussed.

  20. Energy harvesting from controlled buckling of piezoelectric beams

    NASA Astrophysics Data System (ADS)

    Ansari, M. H.; Karami, M. Amin

    2015-11-01

    A piezoelectric vibration energy harvester is presented that can generate electricity from the weight of passing cars or crowds. The energy harvester consists of a piezoelectric beam, which buckles when the device is stepped on. The energy harvester can have a horizontal or vertical configuration. In the vertical (direct) configuration, the piezoelectric beam is vertical and directly sustains the weight of the vehicles or people. In the horizontal (indirect) configuration, the vertical weight is transferred to a horizontal axial force through a scissor-like mechanism. Buckling of the beam results in significant stresses and, thus, large power production. However, if the beam’s buckling is not controlled, the beam will fracture. To prevent this, the axial deformation is constrained to limit the deformations of the beam. In this paper, the energy harvester is analytically modeled. The considered piezoelectric beam is a general non-uniform beam. The natural frequencies, mode shapes, and the critical buckling force corresponding to each mode shape are calculated. The electro-mechanical coupling and the geometric nonlinearities are included in the model. The design criteria for the device are discussed. It is demonstrated that a device, realized with commonly used piezoelectric patches, can generate tens of milliwatts of power from passing car traffic. The proposed device could also be implemented in the sidewalks or integrated in shoe soles for energy generation. One of the key features of the device is its frequency up-conversion characteristics. The piezoelectric beam undergoes free vibrations each time the weight is applied to or removed from the energy harvester. The frequency of the free vibrations is orders of magnitude larger than the frequency of the load. The device is, thus, both efficient and insensitive to the frequency of the force excitations.

  1. Refuse-to-crash: NASA tackles loss of control.

    PubMed

    Croft, John W

    2003-03-01

    The article reviews technologies under study at NASA that will alert pilots of loss of control in time to take action or be able to take necessary action to avoid crashing. Topics discussed include efforts to understand factors behind loss of control, how flight simulator data has been reviewed to develop a new understanding of aircraft aerodynamics, use of models to simulate accidents, and design changes resulting from the data collected.

  2. Control of power, torque, and instability drive using in-shot variable neutral beam energy in tokamaks

    NASA Astrophysics Data System (ADS)

    Pace, D. C.; Collins, C. S.; Crowley, B.; Grierson, B. A.; Heidbrink, W. W.; Pawley, C.; Rauch, J.; Scoville, J. T.; Van Zeeland, M. A.; Zhu, Y. B.; The DIII-D Team

    2017-01-01

    A first-ever demonstration of controlling power and torque injection through time evolution of neutral beam energy has been achieved in recent experiments at the DIII-D tokamak (Luxon 2002 Nucl. Fusion 42 614). Pre-programmed waveforms for the neutral beam energy produce power and torque inputs that can be separately and continuously controlled. Previously, these inputs were tailored using on/off modulation of neutral beams resulting in large perturbations (e.g. power swings of over 1 MW). The new method includes, importantly for experiments, the ability to maintain a fixed injected power while varying the torque. In another case, different beam energy waveforms (in the same plasma conditions) produce significant changes in the observed spectrum of beam ion-driven instabilities. Measurements of beam ion loss show that one energy waveform results in the complete avoidance of coherent losses due to Alfvénic instabilities. This new method of neutral beam operation is intended for further application in a variety of DIII-D experiments including those concerned with high-performance steady state scenarios, fast particle effects, and transport in the low torque regime. Developing this capability would provide similar benefits and improved plasma control for other magnetic confinement fusion facilities.

  3. Control of power, torque, and instability drive using in-shot variable neutral beam energy in tokamaks

    DOE PAGES

    Pace, D. C.; Collins, C. S.; Crowley, B.; ...

    2016-09-28

    A first-ever demonstration of controlling power and torque injection through time evolution of neutral beam energy has been achieved in recent experiments at the DIII-D tokamak. Pre-programmed waveforms for the neutral beam energy produce power and torque inputs that can be separately and continuously controlled. Previously, these inputs were tailored using on/off modulation of neutral beams resulting in large perturbations (e.g. power swings of over 1 MW). The new method includes, importantly for experiments, the ability to maintain a fixed injected power while varying the torque. In another case, different beam energy waveforms (in the same plasma conditions) produce significantmore » changes in the observed spectrum of beam ion-driven instabilities. Measurements of beam ion loss show that one energy waveform results in the complete avoidance of coherent losses due to Alfvénic instabilities. This new method of neutral beam operation is intended for further application in a variety of DIII-D experiments including those concerned with high-performance steady state scenarios, fast particle effects, and transport in the low torque regime. As a result, developing this capability would provide similar benefits and improved plasma control for other magnetic confinement fusion facilities.« less

  4. Control of power, torque, and instability drive using in-shot variable neutral beam energy in tokamaks

    SciTech Connect

    Pace, D. C.; Collins, C. S.; Crowley, B.; Grierson, B. A.; Heidbrink, W. W.; Pawley, C.; Rauch, J.; Scoville, J. T.; Van Zeeland, M. A.; Zhu, Y. B.

    2016-09-28

    A first-ever demonstration of controlling power and torque injection through time evolution of neutral beam energy has been achieved in recent experiments at the DIII-D tokamak. Pre-programmed waveforms for the neutral beam energy produce power and torque inputs that can be separately and continuously controlled. Previously, these inputs were tailored using on/off modulation of neutral beams resulting in large perturbations (e.g. power swings of over 1 MW). The new method includes, importantly for experiments, the ability to maintain a fixed injected power while varying the torque. In another case, different beam energy waveforms (in the same plasma conditions) produce significant changes in the observed spectrum of beam ion-driven instabilities. Measurements of beam ion loss show that one energy waveform results in the complete avoidance of coherent losses due to Alfvénic instabilities. This new method of neutral beam operation is intended for further application in a variety of DIII-D experiments including those concerned with high-performance steady state scenarios, fast particle effects, and transport in the low torque regime. As a result, developing this capability would provide similar benefits and improved plasma control for other magnetic confinement fusion facilities.

  5. On-chip generation and control of the vortex beam

    NASA Astrophysics Data System (ADS)

    Liu, Aiping; Zou, Chang-Ling; Ren, Xifeng; Wang, Qin; Guo, Guang-Can

    2016-05-01

    A method to generate and control the amplitude and phase distributions of an optical vortex beam is proposed. By introducing a holographic grating on the top of a dielectric waveguide, the free space vortex beam and the in-plane guiding wave can be converted to each other. This microscale holographic grating is very robust against the variation of geometry parameters. The designed vortex beam generator can produce the target beam with a fidelity up to 0.93, and the working bandwidth is about 175 nm with the fidelity larger than 0.80. In addition, a multiple generator composed of two holographic gratings on two parallel waveguides is studied, which can perform an effective and flexible modulation on the vortex beam by controlling the phase of the input light. Our work opens an available avenue towards the integrated orbital angular momentum devices with multiple degrees of optical freedom, which can be used for optical tweezers, micronano imaging, information processing, and so on.

  6. On-chip generation and control of the vortex beam

    SciTech Connect

    Liu, Aiping; Wang, Qin; Zou, Chang-Ling; Ren, Xifeng Guo, Guang-Can

    2016-05-02

    A method to generate and control the amplitude and phase distributions of an optical vortex beam is proposed. By introducing a holographic grating on the top of a dielectric waveguide, the free space vortex beam and the in-plane guiding wave can be converted to each other. This microscale holographic grating is very robust against the variation of geometry parameters. The designed vortex beam generator can produce the target beam with a fidelity up to 0.93, and the working bandwidth is about 175 nm with the fidelity larger than 0.80. In addition, a multiple generator composed of two holographic gratings on two parallel waveguides is studied, which can perform an effective and flexible modulation on the vortex beam by controlling the phase of the input light. Our work opens an available avenue towards the integrated orbital angular momentum devices with multiple degrees of optical freedom, which can be used for optical tweezers, micronano imaging, information processing, and so on.

  7. Control system for the Holifield Radioactive Ion Beam Facility

    SciTech Connect

    Tatum, B.A.; Juras, R.C.; Meigs, M.J.

    1995-12-31

    A new accelerator control system is being implemented as part of the development of the Holifield Radioactive Ion Beam Facility (HRIBF), a first generation radioactive ion beam (RIB) facility. The pre- existing accelerator control systems are based on 1970`s technology and addition or alteration of controls is cumbersome and costly. A new, unified control system for the cyclotron and tandem accelerators, the RIB injector, ion sources, and accelerator beam lines is based on a commercial product from Vista Control Systems, Inc. Several other accelerator facilities, as well as numerous industrial sites, are now using this system. The control system is distributed over a number of computers which communicate over Ethernet and is easily extensible. Presently, implementation at the HRIBF is based on VAX/VMS, VAX/ELN, VME, and Allen-Bradley PLC5 programmable logic controller architectures. Expansion to include UNIX platforms and CAMAC hardware support is planned. Operator interface is via X- terminals. The system has proven to be quite powerful, yet is has been easy to implement with a small staff. A Vista users group has resulted in shared software to implement specific controls. This paper details present system features and future implementations at the HRIBF.

  8. Control of gradient catastrophes developing from dark beams.

    PubMed

    Malaguti, S; Corli, A; Trillo, S

    2010-12-15

    We investigate dispersive shock waves developing via a gradient catastrophe during propagation of a dark beam in Kerr defocusing media, showing that a good degree of control, and even shock suppression, is possible by introducing a suitable phase chirp. Insight into the process is obtained by means of a suitable reduction of the hydrodynamic limit of the governing nonlinear Schrödinger equation.

  9. Adaptive robust control of longitudinal and transverse electron beam profiles

    NASA Astrophysics Data System (ADS)

    Rezaeizadeh, Amin; Schilcher, Thomas; Smith, Roy S.

    2016-05-01

    Feedback control of the longitudinal and transverse electron beam profiles are considered to be critical for beam control in accelerators. In the feedback scheme, the longitudinal or transverse beam profile is measured and compared to a desired profile to give an error estimate. The error is then used to act on the appropriate actuators to correct the profile. The role of the transverse feedback is to steer the beam in a particular trajectory, known as the "orbit." The common approach for orbit correction is based on approximately inverting the response matrix, and in the best case, involves regulating or filtering the singular values. In the current contribution, a more systematic and structured way of handling orbit correction is introduced giving robustness against uncertainties in the response matrix. Moreover, the input bounds are treated to avoid violating the limits of the corrector currents. The concept of the robust orbit correction has been successfully tested at the SwissFEL injector test facility. In the SwissFEL machine, a photo-injector laser system extracts electrons from a cathode and a similar robust control method is developed for the longitudinal feedback control of the current profile of the electron bunch. The method manipulates the angles of the crystals in the laser system to produce a desired charge distribution over the electron bunch length. This approach paves the way towards automation of laser pulse stacking.

  10. Feedback Control of Vibrations in a Micromachined Cantilever Beam with Electrostatic Actuators

    NASA Astrophysics Data System (ADS)

    Wang, P. K. C.

    1998-06-01

    The problem of feedback control of vibrations in a micromachined cantilever beam with nonlinear electrostatic actuators is considered. Various forms of nonlinear feedback controls depending on localized spatial averages of the beam velocity and displacement near the beam tip are derived by considering the time rate-of-change of the total energy of the beam. The physical implementation of the derived feedback controls is discussed briefly. The dynamic behaviour of the beam with the derived feedback controls is determined by computer simulation.

  11. Loss-of-Control-Inhibitor Systems for Aircraft

    NASA Technical Reports Server (NTRS)

    AHarrah, Ralph C.

    2007-01-01

    Systems to provide improved tactile feedback to aircraft pilots are being developed to help the pilots maintain harmony between their control actions and the positions of aircraft control surfaces, thereby helping to prevent loss of control. A system of this type, denoted a loss-of-control-inhibitor system (LOCIS) can be implemented as a relatively simple addition to almost any pre-existing flight-control system. The LOCIS concept offers at least a partial solution to the problem of (1) keeping a pilot aware of the state of the control system and the aircraft and (2) maintaining sufficient control under conditions that, as described below, have been known to lead to loss of control. Current commercial aircraft exhibit uneven responses of primary flight-control surfaces to aggressive pilot control commands, leading to deterioration of pilots ability to control their aircraft. In severe cases, this phenomenon can result in loss of control and consequent loss of aircraft. For an older aircraft equipped with a purely mechanical control system, the loss of harmony between a pilot s command action and the control- surface response can be attributed to compliance in the control system (caused, for example, by stretching of control cables, flexing of push rods, or servo-valve distortion). In a newer aircraft equipped with a fly-by-wire control system, the major contributions to loss of harmony between the pilot and the control surfaces are delays attributable to computer cycle time, control shaping, filtering, aliasing, servo-valve distortion, and actuator rate limiting. In addition, a fly-by-wire control system provides no tactile feedback that would enable the pilot to sense such features of the control state as surface flutter, surface jam, position limiting, actuator rate limiting, and control limiting imposed by the aircraft operational envelope. Hence, for example, when a pilot is involved in aggressive closed-loop maneuvering, as when encountering a wake

  12. Ion beam control in laser plasma interaction

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    By a two-stage successive acceleration in laser ion acceleration, our 2.5-dimensional particle-in-cell simulations demonstrate a remarkable increase in ion energy by a few hundreds of MeV; the maximum proton energy reaches about 250MeV. The ions are accelerated by the inductive continuous post-acceleration in a laser plasma interaction together with the target normal sheath acceleration and the breakout afterburner mechanism. An intense short-pulse laser generates a strong current by high-energy electrons accelerated, when an intense short- pulse laser illuminates a plasma target. The strong electric current creates a strong magnetic field along the high-energy electron current in the plasma. During the increase phase in the magnetic field strength, the moving longitudinal inductive electric field is induced by the Faraday law, and accelerates the forward-moving ions continously. The multi-stage acceleration provides a unique controllability in the ion energy and its quality.

  13. Beaconless adaptive-optics technique for HEL beam control

    NASA Astrophysics Data System (ADS)

    Khizhnyak, Anatoliy; Markov, Vladimir

    2016-05-01

    Effective performance of forthcoming laser systems capable of power delivery on a distant target requires an adaptive optics system to correct atmospheric perturbations on the laser beam. The turbulence-induced effects are responsible for beam wobbling, wandering, and intensity scintillation, resulting in degradation of the beam quality and power density on the target. Adaptive optics methods are used to compensate for these negative effects. In its turn, operation of the AOS system requires a reference wave that can be generated by the beacon on the target. This report discusses a beaconless approach for wavefront correction with its performance based on the detection of the target-scattered light. Postprocessing of the beacon-generated light field enables retrieval and detailed characterization of the turbulence-perturbed wavefront -data that is essential to control the adaptive optics module of a high-power laser system.

  14. Ionscan: scanning and control software for proton beam writing

    NASA Astrophysics Data System (ADS)

    Bettiol, A. A.; Udalagama, C. N. B.; Kan, J. A. van; Watt, F.

    2005-04-01

    The proton beam writing technique relies on a precise beam scanning and control system that offers a simple yet flexible interface for the fabrication and design of microstructures. At the Centre for Ion Beam Applications, National University of Singapore, we have developed a suite of programs, collectively known as Ionscan, that cater for the specific needs of proton beam writing. The new version of Ionscan is developed using the Microsoft Visual C++. NET development environment in conjunction with a National Instruments analog output card and NI-DAQ drivers. With the benefit of the experience gained in proton beam writing over the years, numerous enhancements and new features have been added to the scanning software since the first version of the program that was developed using LabVIEW [A.A. Bettiol, J.A. van Khan, T.C. Sum, F. Watt, Nucl. Instr. and Meth. B 181 (2001) 49]. These include the ability to perform combined stage and magnetic (or electrostatic) scanning, which is particularly useful for the fabrication of long waveguides and microfluidic channels over lengths of up to 2.5 cm. Other enhancements include the addition of the Ionutils program which gives the user the ability to design basic structures using an ASCII file format that was developed. This format contains basic information on the shape to be irradiated including the way in which it is scanned.

  15. DIII-D Neutral Beam control system operator interface

    SciTech Connect

    Harris, J.J.; Campbell, G.L.

    1993-10-01

    A centralized graphical user interface has been added to the DIII-D Neutral Beam (NB) control systems for status monitoring and remote control applications. This user interface provides for automatic data acquisition, alarm detection and supervisory control of the four NB programmable logic controllers (PLC) as well as the Mode Control PLC. These PLCs are used for interlocking, control and status of the NB vacuum pumping, gas delivery, and water cooling systems as well as beam mode status and control. The system allows for both a friendly user interface as well as a safe and convenient method of communicating with remote hardware that formerly required interns to access. In the future, to enable high level of control of PLC subsystems, complete procedures is written and executed at the touch of a screen control panel button. The system consists of an IBM compatible 486 computer running the FIX DMACS{trademark} for Windows{trademark} data acquisition and control interface software, a Texas Instruments/Siemens communication card and Phoenix Digital optical communications modules. Communication is achieved via the TIWAY (Texas Instruments protocol link utilizing both fiber optic communications and a copper local area network (LAN). Hardware and software capabilities will be reviewed. Data and alarm reporting, extended monitoring and control capabilities will also be discussed.

  16. Electron beam optics and trajectory control in the Fermi free electron laser delivery system

    NASA Astrophysics Data System (ADS)

    di Mitri, S.; Cornacchia, M.; Scafuri, C.; Sjöström, M.

    2012-01-01

    Electron beam optics (particle betatron motion) and trajectory (centroid secular motion) in the FERMI@Elettra free electron laser (FEL) are modeled and experimentally controlled by means of the elegant particle tracking code. This powerful tool, well known to the accelerator community, is here for the first time fully integrated into the Tango-server based high level software of an FEL facility, thus ensuring optimal charge transport efficiency and superposition of the beam Twiss parameters to the design optics. The software environment, the experimental results collected during the commissioning of FERMI@Elettra, and the comparison with the model are described. As a result, a matching of the beam optics to the design values is accomplished and quantified in terms of the betatron mismatch parameter with relative accuracy down to the 10-3 level. The beam optics control allows accurate energy spread measurements with sub-keV accuracy in dedicated dispersive lines. Trajectory correction and feedback is achieved to a 5μm level with the implementation of theoretical response matrices. In place of the empirical ones, they speed up the process of trajectory control when the machine optics is changed, avoid particle losses that may occur during the on-line computation of experimental matrices, and confirm a good agreement of the experimental magnetic lattice with the model.

  17. A redundant regulator control with low standby losses

    NASA Technical Reports Server (NTRS)

    Andryczyk, R. W.; Peck, S. R.

    1980-01-01

    Shunt regulator circuit for outer-planet-spacecraft radiosotope thermoelectric generator minimizes power-conditioning losses. Unit consists of bank of duplicate regulator control amplifiers and their associated shunt transistors connecter across power supply line. Its high-gain circuitry arranged in redundant configuration in very reliable and is characterized by low standby loss. Circuit can be used on other power-supply applications where size, weight, and reliability are important.

  18. Controlling Losses of the Pension Benefit Guaranty Corporation

    DTIC Science & Technology

    1993-01-01

    Rationale for ERISA 2 The Financial Condition of the Pension Benefit Guaranty Corporation 3 Why Are Losses So Persistent in Federal Pension Insurance...rules embodied in the law, one could argue, Corporation Losing are at fault. ERISA also controls how premiums for pen- sion insurance are set. At...benefits they premium income and insured losses. ERISA , were promising their employees and retirees. probably appropriately, left room for pension A

  19. Surface chemical reactions induced by well-controlled molecular beams: translational energy and molecular orientation control.

    PubMed

    Okada, Michio

    2010-07-07

    I review our recent studies of chemical reactions on single-crystalline Cu and Si surfaces induced by hyperthermal oxygen molecular beams and by oriented molecular beams, respectively. Studies of oxide formation on Cu induced by hyperthermal molecular beams suggest that the translational energy of the incident molecules plays a significant role. The use of hyperthermal molecular beams enables us to open up new chemical reaction paths, and to develop new methods for the fabrication of thin films. Oriented molecular beams also demonstrate the possibility for controlling surface chemical reactions by varying the orientation of the incident molecules. The steric effects found on Si surfaces hint at new ways of achieving material fabrication on Si surfaces. Controlling the initial conditions of incoming molecules is a powerful tool for creating new materials on surfaces with well-controlled chemical reactions. © 2010 IOP Publishing Ltd

  20. Fluid loss control differences of crosslinked and linear fracturing fluids

    SciTech Connect

    Zigrye, J.L.; Sievert, J.A.; Whitfill, D.L.

    1983-10-01

    Three fracturing fluids-a cross-linked guar, a delayed hydrating guar and a linear guar-were tested for fluid loss control at set time intervals while being conditioned in a heated, pressurized flow loop. Each fluid was tested with three different fluid loss additive systems: diesel, silica flour, and a combination of diesel and silica flour. The cross-linked system was also tested with two additional fluid loss additive systems. They were diesel plus an anionic surfactant and the combination of diesel/silica flour plus the anionic surfactant. These tests show that the fluid loss of cross-linked fracturing fluids is best controlled by using diesel in combination with a surfactant or a properly sized particulate material. The fluid loss of linear fluids is controlled best with particulate additives. Therefore, it is important to take into account the type of fracturing fluid that is being used for a particular job when planning which fluid loss additives to use.

  1. Polymer particulates control fluid loss during well completions

    SciTech Connect

    Ali, S.A.; Nguyen, P.D.; Weaver, J.D.

    1997-05-12

    In its Gulf of Mexico operations, Chevron U.S.A. Production Co. has effectively controlled completion fluid loss to the formation by including nondamaging, soluble particulates (NSP) in the fluid. In seven Chevron wells recently completed in the Gulf of Mexico, fluid loss dropped to very low levels or zero with NSP included in the completion fluid. Conventional particulate-based, fluid-loss control methods have shown varying degrees of fluid-loss control. But these methods have the potential to cause near well bore damage and long cleanup periods. In contrast, the NSP fluid-loss additive can be cleaned up readily and causes very little decrease in formation permeability. NSP is stable enough to store and is provided as a slurry concentrate that can be dispersed easily in completion fluid. It can be pumped and mixed in the field with conventional equipment. NSP forms a barrier or filter cake that covers the surface of the formation or perforation where fluid loss is occurring.

  2. Shielding NSLS-II light source: Importance of geometry for calculating radiation levels from beam losses [Shielding Synchrotron Light Sources: Importance of geometry for calculating radiation levels from beam losses

    DOE PAGES

    Kramer, S. L.; Ghosh, V. J.; Breitfeller, M.; ...

    2016-08-10

    Third generation high brightness light sources are designed to have low emittance and high current beams, which contribute to higher beam loss rates that will be compensated by Top-Off injection. Shielding for these higher loss rates will be critical to protect the projected higher occupancy factors for the users. Top-Off injection requires a full energy injector, which will demand greater consideration of the potential abnormal beam miss-steering and localized losses that could occur. The high energy electron injection beam produces significantly higher neutron component dose to the experimental floor than a lower energy beam injection and ramped operations. Minimizing thismore » dose will require adequate knowledge of where the miss-steered beam can occur and sufficient EM shielding close to the loss point, in order to attenuate the energy of the particles in the EM shower below the neutron production threshold (<10 MeV), which will spread the incident energy on the bulk shield walls and thereby the dose penetrating the shield walls. Designing supplemental shielding near the loss point using the analytic shielding model is shown to be inadequate because of its lack of geometry specification for the EM shower process. To predict the dose rates outside the tunnel requires detailed description of the geometry and materials that the beam losses will encounter inside the tunnel. Modern radiation shielding Monte-Carlo codes, like FLUKA, can handle this geometric description of the radiation transport process in sufficient detail, allowing accurate predictions of the dose rates expected and the ability to show weaknesses in the design before a high radiation incident occurs. The effort required to adequately define the accelerator geometry for these codes has been greatly reduced with the implementation of the graphical interface of FLAIR to FLUKA. This made the effective shielding process for NSLS-II quite accurate and reliable. Lastly, the principles used to provide

  3. Semiconductor diode laser having an intracavity spatial phase controller for beam control and switching

    DOEpatents

    Hohimer, John P.

    1994-01-01

    A high-power broad-area semiconductor laser having a intracavity spatial phase controller is disclosed. The integrated intracavity spatial phase controller is easily formed by patterning an electrical contact metallization layer when fabricating the semiconductor laser. This spatial phase controller changes the normally broad far-field emission beam of such a laser into a single-lobed near-diffraction-limited beam at pulsed output powers of over 400 mW. Two operating modes, a thermal and a gain operating mode, exist for the phase controller, allowing for steering and switching the beam as the modes of operation are switched, and the emission beam may be scanned, for example, over a range of 1.4 degrees or switched by 8 degrees. More than one spatial phase controller may be integrated into the laser structure.

  4. Semiconductor diode laser having an intracavity spatial phase controller for beam control and switching

    DOEpatents

    Hohimer, J.P.

    1994-06-07

    A high-power broad-area semiconductor laser having a intracavity spatial phase controller is disclosed. The integrated intracavity spatial phase controller is easily formed by patterning an electrical contact metallization layer when fabricating the semiconductor laser. This spatial phase controller changes the normally broad far-field emission beam of such a laser into a single-lobed near-diffraction-limited beam at pulsed output powers of over 400 mW. Two operating modes, a thermal and a gain operating mode, exist for the phase controller, allowing for steering and switching the beam as the modes of operation are switched, and the emission beam may be scanned, for example, over a range of 1.4 degrees or switched by 8 degrees. More than one spatial phase controller may be integrated into the laser structure. 6 figs.

  5. Beam loss simulations for the implementation of the Hard X-Ray Self-Seeding system at European XFEL

    NASA Astrophysics Data System (ADS)

    Liu, Shan; Decking, Winfried; Fröhlich, Lars

    2017-07-01

    The European XFEL is designed to be operated with a nominal beam energy of 17.5 GeV at a maximum repetition rate of 27000 bunches/second. The high repetition rate together with the high loss sensitivity of the undulators raises serious radiation damage concern, especially for the implementation of the Hard X-ray Self-Seeding (HXRSS) system, where a 100 µm thick diamond crystal will be inserted close to the beam in the undulator section. Since the seeding power level highly depends on the delay of the electron beam with respect to the photon beam, it is crucial to define the minimum electron beam offset to the edge of the crystal in the HXRSS chicane. At European XFEL a ∼200 m long post-linac collimation section has been designed to protect the undulators. In the HXRSS scheme, however, beam halo particles hitting the crystal can generate additional radiation. Particle tracking simulations have been performed using GEANT4 and BDSIM for the undulator and the collimation section, respectively. The critical number of electrons allowed to hit the crystal is estimated for a certain operation mode and the efficiency of beam halo collimation is investigated to predict the minimum HXRSS chicane delay.

  6. Effects of wireless packet loss in industrial process control systems.

    PubMed

    Liu, Yongkang; Candell, Richard; Moayeri, Nader

    2017-02-09

    Timely and reliable sensing and actuation control are essential in networked control. This depends on not only the precision/quality of the sensors and actuators used but also on how well the communications links between the field instruments and the controller have been designed. Wireless networking offers simple deployment, reconfigurability, scalability, and reduced operational expenditure, and is easier to upgrade than wired solutions. However, the adoption of wireless networking has been slow in industrial process control due to the stochastic and less than 100% reliable nature of wireless communications and lack of a model to evaluate the effects of such communications imperfections on the overall control performance. In this paper, we study how control performance is affected by wireless link quality, which in turn is adversely affected by severe propagation loss in harsh industrial environments, co-channel interference, and unintended interference from other devices. We select the Tennessee Eastman Challenge Model (TE) for our study. A decentralized process control system, first proposed by N. Ricker, is adopted that employs 41 sensors and 12 actuators to manage the production process in the TE plant. We consider the scenario where wireless links are used to periodically transmit essential sensor measurement data, such as pressure, temperature and chemical composition to the controller as well as control commands to manipulate the actuators according to predetermined setpoints. We consider two models for packet loss in the wireless links, namely, an independent and identically distributed (IID) packet loss model and the two-state Gilbert-Elliot (GE) channel model. While the former is a random loss model, the latter can model bursty losses. With each channel model, the performance of the simulated decentralized controller using wireless links is compared with the one using wired links providing instant and 100% reliable communications. The sensitivity of the

  7. Control System of Neutral Beam Injection on HT-7

    NASA Astrophysics Data System (ADS)

    Wang, Yongjun; Hu, Chundong; Liu, Zhimin; Liu, Sheng; Song, Shihua; Yang, Daoye

    2005-06-01

    Neutral Beam Injection control system (NBICS) is constructed to measure the plasma current, Magnet current, vacuum pressure, cryopump temperature, control water cooling, filament voltage, and power supply, etc. The NBICS, consisting mainly of a Programmable Logic Controller (PLC) subsystem, data acquisition and processing subsystem and cryopump and vacuum pressure monitoring subsystem, has successfully been used on a NBI device. In this article, the design of NBICS on HT-7 is discussed and each subsystem is described in particular. In addition, some experimental results are reported which are very important data for further research related to the HT-7 tokamak.

  8. Simultaneous active control of flexural and extensional waves in beams

    NASA Technical Reports Server (NTRS)

    Fuller, C. R.; Gibbs, G. P.; Silcox, R. J.

    1990-01-01

    The simultaneous active control of flexural and extensional vibrations in elastic beams is experimentally investigated. The results demonstrate that using pairs of piezoceramic transducers, whose elements are symmetrically located and independently controlled by a multichannel adaptive controller, enables the high attenuation of both flexural and extensional response. This capability is due to the nature of the piezoceramic element, which when bonded to the surface of the structure and electrically excited, exerts a surface strain on the structure. This strain enables input of both shear forces and moments into the structural system. The results are applicable to many situations where extensional vibrations couple to large flexural vibrations and subsequently radiate significant sound levels.

  9. Design of Main Control Console Software in EAST Neutral Beam Injector's Control System for the First Beam Line

    NASA Astrophysics Data System (ADS)

    Wu, De-Yun; Hu, Chun-Dong; Sheng, Peng; Zhao, Yuan-Zhe; Zhang, Xiao-Dan; Cui, Qing-Long

    2013-10-01

    Neutral beam injector is one of the main plasma heating and plasma current driving methods for experimental advanced superconducting tokomaks (EAST). In order to realize visual operation of EAST neutral beam injector's control system (NBICS), main control console (MCC) is developed to work as the human-machine interface between the NBICS and physical operator. It can meet the requirements of visual control of NBICS by providing a user graphic interface. With the specific algorithms, the setup of power supply sequence is relatively independent and simple. Displaying the real-time feedback of the subsystems provides a reference for operators to monitor the status of the system. The MCC software runs on a Windows system and uses C++ language code while using client/server (C/S) mode, multithreading and cyclic redundancy check technology. The experimental results have proved that MCC provides a stability and reliability operation of NBICS and works as an effective man-machine interface at the same time.

  10. Ultra-precise holographic beam shaping for microscopic quantum control.

    PubMed

    Zupancic, Philip; Preiss, Philipp M; Ma, Ruichao; Lukin, Alexander; Eric Tai, M; Rispoli, Matthew; Islam, Rajibul; Greiner, Markus

    2016-06-27

    High-resolution addressing of individual ultracold atoms, trapped ions or solid state emitters allows for exquisite control in quantum optics experiments. This becomes possible through large aperture magnifying optics that project microscopic light patterns with diffraction limited performance. We use programmable amplitude holograms generated on a digital micromirror device to create arbitrary microscopic beam shapes with full phase and amplitude control. The system self-corrects for aberrations of up to several λ and reduces them to λ/50, leading to light patterns with a precision on the 10-4 level. We demonstrate aberration-compensated beam shaping in an optical lattice experiment and perform single-site addressing in a quantum gas microscope for 87Rb.

  11. Advanced control of nonlinear beams with Pancharatnam-Berry metasurfaces

    NASA Astrophysics Data System (ADS)

    Tymchenko, M.; Gomez-Diaz, J. S.; Lee, J.; Nookala, N.; Belkin, M. A.; Alù, A.

    2016-12-01

    The application of the Pancharatnam-Berry (PB) phase approach to the design of nonlinear metasurfaces has recently enabled subdiffractive phase control over the generated nonlinear fields, embedding phased array features in ultrathin structures. Here, we rigorously model, analyze, and design highly efficient nonlinear metasurfaces with advanced functionalities, including the generation of pencil beams steered in arbitrary directions in space, as well as vortex beams with polarization-dependent angular momentum, and we extend the PB approach to various nonlinear processes. To this purpose, we develop an accurate and efficient theoretical framework—inspired by the linear phase array theory—based on the effective nonlinear susceptibility method, thus avoiding the use of time-consuming numerical simulations. Our findings allow exploiting the flat nonlinear optics paradigm, enabling exciting applications based on subwavelength field control over flat and large-scale structures with giant nonlinear responses.

  12. Electron Beam Return-Current Losses in Solar Flares: Initial Comparison of Analytical and Numerical Results

    NASA Technical Reports Server (NTRS)

    Holman, Gordon

    2010-01-01

    Accelerated electrons play an important role in the energetics of solar flares. Understanding the process or processes that accelerate these electrons to high, nonthermal energies also depends on understanding the evolution of these electrons between the acceleration region and the region where they are observed through their hard X-ray or radio emission. Energy losses in the co-spatial electric field that drives the current-neutralizing return current can flatten the electron distribution toward low energies. This in turn flattens the corresponding bremsstrahlung hard X-ray spectrum toward low energies. The lost electron beam energy also enhances heating in the coronal part of the flare loop. Extending earlier work by Knight & Sturrock (1977), Emslie (1980), Diakonov & Somov (1988), and Litvinenko & Somov (1991), I have derived analytical and semi-analytical results for the nonthermal electron distribution function and the self-consistent electric field strength in the presence of a steady-state return-current. I review these results, presented previously at the 2009 SPD Meeting in Boulder, CO, and compare them and computed X-ray spectra with numerical results obtained by Zharkova & Gordovskii (2005, 2006). The phYSical significance of similarities and differences in the results will be emphasized. This work is supported by NASA's Heliophysics Guest Investigator Program and the RHESSI Project.

  13. Measurement profiles of nano-scale ion beam for optimized radiation energy losses

    NASA Astrophysics Data System (ADS)

    Woo, T. H.; Cho, H. S.

    2011-10-01

    The behavior of charged particles is investigated for nano-scale ion beam therapy using a medical accelerator. Computational work is performed for the Bragg-peak simulation, which is focused on human organ material of pancreas and thyroid. The Results show that the trends of the dose have several different kinds of distributions. Before constructing a heavy ion collider, this study can give us the reliability of the therapeutic effect. Realistic treatment using human organs is calculated in a simple and cost effective manner using the computational code, the Stopping and Range of Ions in Matter 2008 (SRIM 2008). Considering the safety of the therapy, it is suggested to give a patient orient planning of the cancer therapy. The energy losses in ionization and phonon are analyzed, which are the behaviors in the molecular level nano-scopic investigation. The different fluctuations are shown at 150 MeV, where the lowest temperature is found in proton and pancreas case. Finally, the protocol for the radiation therapy is constructed by the simulation in which the procedure for a better therapy is selected. An experimental measurement incorporated with the simulations could be programmed by this protocol.

  14. Electron Beam Return-Current Losses in Solar Flares: Initial Comparison of Analytical and Numerical Results

    NASA Technical Reports Server (NTRS)

    Holman, Gordon

    2010-01-01

    Accelerated electrons play an important role in the energetics of solar flares. Understanding the process or processes that accelerate these electrons to high, nonthermal energies also depends on understanding the evolution of these electrons between the acceleration region and the region where they are observed through their hard X-ray or radio emission. Energy losses in the co-spatial electric field that drives the current-neutralizing return current can flatten the electron distribution toward low energies. This in turn flattens the corresponding bremsstrahlung hard X-ray spectrum toward low energies. The lost electron beam energy also enhances heating in the coronal part of the flare loop. Extending earlier work by Knight & Sturrock (1977), Emslie (1980), Diakonov & Somov (1988), and Litvinenko & Somov (1991), I have derived analytical and semi-analytical results for the nonthermal electron distribution function and the self-consistent electric field strength in the presence of a steady-state return-current. I review these results, presented previously at the 2009 SPD Meeting in Boulder, CO, and compare them and computed X-ray spectra with numerical results obtained by Zharkova & Gordovskii (2005, 2006). The phYSical significance of similarities and differences in the results will be emphasized. This work is supported by NASA's Heliophysics Guest Investigator Program and the RHESSI Project.

  15. Method and apparatus for loss of control inhibitor systems

    NASA Technical Reports Server (NTRS)

    A'Harrah, Ralph C. (Inventor)

    2007-01-01

    Active and adaptive systems and methods to prevent loss of control incidents by providing tactile feedback to a vehicle operator are disclosed. According to the present invention, an operator gives a control input to an inceptor. An inceptor sensor measures an inceptor input value of the control input. The inceptor input is used as an input to a Steady-State Inceptor Input/Effector Output Model that models the vehicle control system design. A desired effector output from the inceptor input is generated from the model. The desired effector output is compared to an actual effector output to get a distortion metric. A feedback force is generated as a function of the distortion metric. The feedback force is used as an input to a feedback force generator which generates a loss of control inhibitor system (LOCIS) force back to the inceptor. The LOCIS force is felt by the operator through the inceptor.

  16. Method and apparatus for loss of control inhibitor systems

    NASA Technical Reports Server (NTRS)

    A'Harrah, Ralph C. (Inventor)

    2007-01-01

    Active and adaptive systems and methods to prevent loss of control incidents by providing tactile feedback to a vehicle operator are disclosed. According to the present invention, an operator gives a control input to an inceptor. An inceptor sensor measures an inceptor input value of the control input. The inceptor input is used as an input to a Steady-State Inceptor Input/Effector Output Model that models the vehicle control system design. A desired effector output from the inceptor input is generated from the model. The desired effector output is compared to an actual effector output to get a distortion metric. A feedback force is generated as a function of the distortion metric. The feedback force is used as an input to a feedback force generator which generates a loss of control inhibitor system (LOCIS) force back to the inceptor. The LOCIS force is felt by the operator through the inceptor.

  17. Active control of transmission loss with smart foams.

    PubMed

    Kundu, Abhishek; Berry, Alain

    2011-02-01

    Smart foams combine the complimentary advantages of passive foam material and spatially distributed piezoelectric actuator embedded in it for active noise control applications. In this paper, the problem of improving the transmission loss of smart foams using active control strategies has been investigated both numerically and experimentally inside a waveguide under the condition of plane wave propagation. The finite element simulation of a coupled noise control system has been undertaken with three different smart foam designs and their effectiveness in cancelling the transmitted wave downstream of the smart foam have been studied. The simulation results provide insight into the physical phenomenon of active noise cancellation and explain the impact of the smart foam designs on the optimal active control results. Experimental studies aimed at implementing the real-time control for transmission loss optimization have been performed using the classical single input/single output filtered-reference least mean squares algorithm. The active control results with broadband and single frequency primary source inputs demonstrate a good improvement in the transmission loss of the smart foams. The study gives a comparative description of the transmission and absorption control problems in light of the modification of the vibration response of the piezoelectric actuator under active control.

  18. Electronically-Controlled Beam-Steering through Vanadium Dioxide Metasurfaces

    PubMed Central

    Hashemi, Mohammed Reza M.; Yang, Shang-Hua; Wang, Tongyu; Sepúlveda, Nelson; Jarrahi, Mona

    2016-01-01

    Engineered metamaterials offer unique functionalities for manipulating the spectral and spatial properties of electromagnetic waves in unconventional ways. Here, we report a novel approach for making reconfigurable metasurfaces capable of deflecting electromagnetic waves in an electronically controllable fashion. This is accomplished by tilting the phase front of waves through a two-dimensional array of resonant metasurface unit-cells with electronically-controlled phase-change materials embedded inside. Such metasurfaces can be placed at the output facet of any electromagnetic radiation source to deflect electromagnetic waves at a desired frequency, ranging from millimeter-wave to far-infrared frequencies. Our design does not use any mechanical elements, external light sources, or reflectarrays, creating, for the first time, a highly robust and fully-integrated beam-steering device solution. We demonstrate a proof-of-concept beam-steering metasurface optimized for operation at 100 GHz, offering up to 44° beam deflection in both horizontal and vertical directions. Dynamic control of electromagnetic wave propagation direction through this unique platform could be transformative for various imaging, sensing, and communication applications, among others. PMID:27739471

  19. Advanced Lyapunov control of a novel laser beam tracking system

    NASA Astrophysics Data System (ADS)

    Nikulin, Vladimir V.; Sofka, Jozef; Skormin, Victor A.

    2005-05-01

    Laser communication systems developed for mobile platforms, such as satellites, aircraft, and terrain vehicles, require fast wide-range beam-steering devices to establish and maintain a communication link. Conventionally, the low-bandwidth, high-steering-range part of the beam-positioning task is performed by gimbals that inherently constitutes the system bottleneck in terms of reliability, accuracy and dynamic performance. Omni-WristTM, a novel robotic sensor mount capable of carrying a payload of 5 lb and providing a full 180-deg hemisphere of azimuth/declination motion is known to be free of most of the deficiencies of gimbals. Provided with appropriate controls, it has the potential to become a new generation of gimbals systems. The approach we demonstrate describes an adaptive controller enabling Omni-WristTM to be utilized as a part of a laser beam positioning system. It is based on a Lyapunov function that ensures global asymptotic stability of the entire system while achieving high tracking accuracy. The proposed scheme is highly robust, does not require knowledge of complex system dynamics, and facilitates independent control of each channel by full decoupling of the Omni-WristTM dynamics. We summarize the basic algorithm and demonstrate the results obtained in the simulation environment.

  20. Electronically-Controlled Beam-Steering through Vanadium Dioxide Metasurfaces

    NASA Astrophysics Data System (ADS)

    Hashemi, Mohammed Reza M.; Yang, Shang-Hua; Wang, Tongyu; Sepúlveda, Nelson; Jarrahi, Mona

    2016-10-01

    Engineered metamaterials offer unique functionalities for manipulating the spectral and spatial properties of electromagnetic waves in unconventional ways. Here, we report a novel approach for making reconfigurable metasurfaces capable of deflecting electromagnetic waves in an electronically controllable fashion. This is accomplished by tilting the phase front of waves through a two-dimensional array of resonant metasurface unit-cells with electronically-controlled phase-change materials embedded inside. Such metasurfaces can be placed at the output facet of any electromagnetic radiation source to deflect electromagnetic waves at a desired frequency, ranging from millimeter-wave to far-infrared frequencies. Our design does not use any mechanical elements, external light sources, or reflectarrays, creating, for the first time, a highly robust and fully-integrated beam-steering device solution. We demonstrate a proof-of-concept beam-steering metasurface optimized for operation at 100 GHz, offering up to 44° beam deflection in both horizontal and vertical directions. Dynamic control of electromagnetic wave propagation direction through this unique platform could be transformative for various imaging, sensing, and communication applications, among others.

  1. Electronically-Controlled Beam-Steering through Vanadium Dioxide Metasurfaces.

    PubMed

    Hashemi, Mohammed Reza M; Yang, Shang-Hua; Wang, Tongyu; Sepúlveda, Nelson; Jarrahi, Mona

    2016-10-14

    Engineered metamaterials offer unique functionalities for manipulating the spectral and spatial properties of electromagnetic waves in unconventional ways. Here, we report a novel approach for making reconfigurable metasurfaces capable of deflecting electromagnetic waves in an electronically controllable fashion. This is accomplished by tilting the phase front of waves through a two-dimensional array of resonant metasurface unit-cells with electronically-controlled phase-change materials embedded inside. Such metasurfaces can be placed at the output facet of any electromagnetic radiation source to deflect electromagnetic waves at a desired frequency, ranging from millimeter-wave to far-infrared frequencies. Our design does not use any mechanical elements, external light sources, or reflectarrays, creating, for the first time, a highly robust and fully-integrated beam-steering device solution. We demonstrate a proof-of-concept beam-steering metasurface optimized for operation at 100 GHz, offering up to 44° beam deflection in both horizontal and vertical directions. Dynamic control of electromagnetic wave propagation direction through this unique platform could be transformative for various imaging, sensing, and communication applications, among others.

  2. Adaptive control of laser beams propagating in the atmosphere

    NASA Astrophysics Data System (ADS)

    Kanev, Feodor; Atepaeva, Natalya; Lukin, Vladimir; Makenova, Nailya

    2006-09-01

    In the present paper efficiency of adaptive correction is analyzed in the turbulent atmosphere and under the conditions of thermal blooming. A numerical model of a typical adaptive optics system was developed to carry out the investigations. As it is known, phase conjugation and multidither, i.e., the algorithms commonly employed to correct for thermal and turbulent distortions of laser beams are unstable in nonlinear medium. We demonstrated that stability of phase control is possible to increase introducing the modifications of the algorithms. Also we demonstrated that phase compensation does not insure complete correction for thermal or turbulent aberrations induced by an atmospheric layer. To correct for aberrations under these conditions it is possible to employ amplitude-phase control over the beam, for example, to use the wavefront reversal algorithm. Realization of the algorithm is possible in a two-mirror adaptive system in which the control over beam phase is performed in two planes at the access to the medium. In numerical experiments it was shown that the two-mirror system insures the absolute compensation for a thin turbulent layer placed at arbitrary distance from the aperture of a laser source and high effectiveness of compensation for distributed lens comparing with phase-only algorithms.

  3. Optical Beam Jitter Control for the NPS HEL Beam Control Testbed

    DTIC Science & Technology

    2011-11-01

    PI Control , RMS = 6.13 Adaptive Filter, RMS...3.76 0 2 4 6 8 10 -60 -40 -20 0 20 40 60 80 sec e rr o r No Control, RMS = 42.64 PI Control , RMS = 10.44 Adaptive Filter, RMS = 1.44 Figure 22...e rr o r (d B ) No Control PI Control Adaptive Filter 0 5 10 15 20 25 20 40 60 80 100 120 Hz e rr o r (d B ) No Control PI Control Adaptive Filter

  4. Mitigation of beam fluctuation due to atmospheric turbulence and prediction of control quality using intelligent decision-making tools.

    PubMed

    Raj, A Arockia Bazil; Selvi, J Arputha Vijaya; Kumar, D; Sivakumaran, N

    2014-06-10

    In free-space optical link (FSOL), atmospheric turbulence causes fluctuations in both intensity and phase of the received beam and impairing link performance. The beam motion is one of the main causes for major power loss. This paper presents an investigation on the performance of two types of controller designed for aiming a laser beam to be at a particular spot under dynamic disturbances. The multiple experiment observability nonlinear input-output data mapping is used as the principal components for controllers design. The first design is based on the Taguchi method while the second is artificial neural network method. These controllers process the beam location information from a static linear map of 2D plane: optoelectronic position detector, as observer, and then generate the necessary outputs to steer the beam with a microelectromechanical mirror: fast steering mirror. The beam centroid is computed using monopulse algorithm. Evidence of suitability and effectiveness of the proposed controllers are comprehensively assessed and quantitatively measured in terms of coefficient of correlation, correction speed, control exactness, centroid displacement, and stability of the receiver signal through the experimental results from the FSO link setup established for the horizontal range of 0.5 km at an altitude of 15.25 m. The test field type is open flat terrain, grass, and few isolated obstacles.

  5. Summary report of working group 5 : beam generation, monitoring, and control.;

    SciTech Connect

    Lewellen, J. W.; Piot, P.; Accelerator Systems Division; Northern Illinois Univ.

    2006-01-01

    The working group on beam quality, diagnostics, and control at the 12th Advanced Accelerator Concepts Workshop held a series of meetings during the Workshop. The generation of bright charged-particle beams (in particular electron and positron beams), along with state-of-the-art beam diagnostics and synchronization were discussed.

  6. Acute and Chronic Stress: The Effects of Loss of Control

    DTIC Science & Technology

    1996-07-31

    perceived control has been associated with elevations in sympathetic arousal, impaired task performance, and helpless behavior ( Abramson , Seligman...atypical cytology based on self-reported recently experienced personal loss and expressed feelings of helplessness or hopelessness during a...century. During the "Great Depression " hoboism and displaced families 39 were prominent in the social literature (Sutherland & Locke, 1936; Park

  7. 76 FR 31543 - Controlled Groups; Deferral of Losses; Hearing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-01

    ... Internal Revenue Service 26 CFR Part 1 RIN 1545-BI92 Controlled Groups; Deferral of Losses; Hearing AGENCY: Internal Revenue Service (IRS), Treasury. ACTION: Notice of public hearing on proposed rulemaking. SUMMARY: This document provides notice of public hearing on a notice of proposed rulemaking providing guidance...

  8. Sliding Mode Control of a Slewing Flexible Beam

    NASA Technical Reports Server (NTRS)

    Wilson, David G.; Parker, Gordon G.; Starr, Gregory P.; Robinett, Rush D., III

    1997-01-01

    An output feedback sliding mode controller (SMC) is proposed to minimize the effects of vibrations of slewing flexible manipulators. A spline trajectory is used to generate ideal position and velocity commands. Constrained nonlinear optimization techniques are used to both calibrate nonlinear models and determine optimized gains to produce a rest-to-rest, residual vibration-free maneuver. Vibration-free maneuvers are important for current and future NASA space missions. This study required the development of the nonlinear dynamic system equations of motion; robust control law design; numerical implementation; system identification; and verification using the Sandia National Laboratories flexible robot testbed. Results are shown for a slewing flexible beam.

  9. The system of RF beam control for electron gun

    NASA Astrophysics Data System (ADS)

    Barnyakov, A. M.; Chernousov, Yu. D.; Ivannikov, V. I.; Levichev, A. E.; Shebolaev, I. V.

    2015-06-01

    The system of RF control of three-electrode electron gun current is described. It consists of a source of microwave signal, coaxial line, coaxial RF switch and RF antenna lead. The system allows one to get the electron beam in the form of bunches with the frequency of the accelerating section to achieve the capture of particles in the acceleration mode close to 100%. The results of calculation and analysis of the elements of the system are presented. Characteristics of the devices are obtained experimentally. The results of using RF control in three-electrode electron gun at electron linear accelerator are described.

  10. Constrained modes in control theory - Transmission zeros of uniform beams

    NASA Technical Reports Server (NTRS)

    Williams, T.

    1992-01-01

    Mathematical arguments are presented demonstrating that the well-established control system concept of the transmission zero is very closely related to the structural concept of the constrained mode. It is shown that the transmission zeros of a flexible structure form a set of constrained natural frequencies for it, with the constraints depending explicitly on the locations and the types of sensors and actuators used for control. Based on this formulation, an algorithm is derived and used to produce dimensionless plots of the zero of a uniform beam with a compatible sensor/actuator pair.

  11. Bending, longitudinal and torsional wave transmission on Euler-Bernoulli and Timoshenko beams with high propagation losses.

    PubMed

    Wang, X; Hopkins, C

    2016-10-01

    Advanced Statistical Energy Analysis (ASEA) is used to predict vibration transmission across coupled beams which support multiple wave types up to high frequencies where Timoshenko theory is valid. Bending-longitudinal and bending-torsional models are considered for an L-junction and rectangular beam frame. Comparisons are made with measurements, Finite Element Methods (FEM) and Statistical Energy Analysis (SEA). When beams support at least two local modes for each wave type in a frequency band and the modal overlap factor is at least 0.1, measurements and FEM have relatively smooth curves. Agreement between measurements, FEM, and ASEA demonstrates that ASEA is able to predict high propagation losses which are not accounted for with SEA. These propagation losses tend to become more important at high frequencies with relatively high internal loss factors and can occur when there is more than one wave type. At such high frequencies, Timoshenko theory, rather than Euler-Bernoulli theory, is often required. Timoshenko theory is incorporated in ASEA and SEA using wave theory transmission coefficients derived assuming Euler-Bernoulli theory, but using Timoshenko group velocity when calculating coupling loss factors. The changeover between theories is appropriate above the frequency where there is a 26% difference between Euler-Bernoulli and Timoshenko group velocities.

  12. The RF beam control system for the Brookhaven AGS synchrotron

    SciTech Connect

    Brennan, J.M.

    1992-09-01

    The new 1.5 GeV Booster synchrotron completes the injector chain for the Relativistic Heavy Ion Collider, RHIC. It enables the AGS to accelerate all heavy ions to 14 GeV/c for collider operation and also in the intensity of the AGS for fixed-target experiments by a factor of four. The ultra-high vacuum enables acceleration of partially stripped ions from the Tandem Van de Graaff to energies sufficient for complete stripping. For high intensities, it accelerates the 200 MeV linac beam in four batches of three bunches per AGS cycle. At 1.5 {times} 10{sup 13} protons per batch, it has the same space charge tune spread as the AGS at 200 MeV. This variety of applications means the Booster must accommodate a very wide range of particle masses and intensities. Since it operates in a Pulse-by-Pulse Modulation mode at 7.5 Hz, the computer controlled functions of time and magnetic field, and the 64 timing triggers of the beam control system take on unique values for each of four PPM users. Beams of {sup 197}Au{sup +33} ions and protons have been accelerated in the same PPM cycle.

  13. The RF beam control system for the Brookhaven AGS synchrotron

    SciTech Connect

    Brennan, J.M.

    1992-01-01

    The new 1.5 GeV Booster synchrotron completes the injector chain for the Relativistic Heavy Ion Collider, RHIC. It enables the AGS to accelerate all heavy ions to 14 GeV/c for collider operation and also in the intensity of the AGS for fixed-target experiments by a factor of four. The ultra-high vacuum enables acceleration of partially stripped ions from the Tandem Van de Graaff to energies sufficient for complete stripping. For high intensities, it accelerates the 200 MeV linac beam in four batches of three bunches per AGS cycle. At 1.5 {times} 10{sup 13} protons per batch, it has the same space charge tune spread as the AGS at 200 MeV. This variety of applications means the Booster must accommodate a very wide range of particle masses and intensities. Since it operates in a Pulse-by-Pulse Modulation mode at 7.5 Hz, the computer controlled functions of time and magnetic field, and the 64 timing triggers of the beam control system take on unique values for each of four PPM users. Beams of {sup 197}Au{sup +33} ions and protons have been accelerated in the same PPM cycle.

  14. An ultra-compact and low loss passive beam-forming network integrated on chip with off chip linear array

    SciTech Connect

    Lepkowski, Stefan Mark

    2015-05-01

    The work here presents a review of beam forming architectures. As an example, the author presents an 8x8 Butler Matrix passive beam forming network including the schematic, design/modeling, operation, and simulated results. The limiting factor in traditional beam formers has been the large size dictated by transmission line based couplers. By replacing these couplers with transformer-based couplers, the matrix size is reduced substantially allowing for on chip compact integration. In the example presented, the core area, including the antenna crossover, measures 0.82mm×0.39mm (0.48% the size of a branch line coupler at the same frequency). The simulated beam forming achieves a peak PNR of 17.1 dB and 15dB from 57 to 63GHz. At the 60GHz center frequency the average insertion loss is simulated to be 3.26dB. The 8x8 Butler Matrix feeds into an 8-element antenna array to show the array patterns with single beam and adjacent beam isolation.

  15. Vibration control in smart coupled beams subjected to pulse excitations

    NASA Astrophysics Data System (ADS)

    Pisarski, Dominik; Bajer, Czesław I.; Dyniewicz, Bartłomiej; Bajkowski, Jacek M.

    2016-10-01

    In this paper, a control method to stabilize the vibration of adjacent structures is presented. The control is realized by changes of the stiffness parameters of the structure's couplers. A pulse excitation applied to the coupled adjacent beams is imposed as the kinematic excitation. For such a representation, the designed control law provides the best rate of energy dissipation. By means of a stability analysis, the performance in different structural settings is studied. The efficiency of the proposed strategy is examined via numerical simulations. In terms of the assumed energy metric, the controlled structure outperforms its passively damped equivalent by over 50 percent. The functionality of the proposed control strategy should attract the attention of practising engineers who seek solutions to upgrade existing damping systems.

  16. Short-Pulse Electron-Beam Propagation Experiments in a Controlled-Environment Chamber.

    DTIC Science & Technology

    1982-03-08

    pressures (400-550 Pa), magnetic probe data were used to estimate induced electric fields and nose erosion caused by ohmic energy loss . Results were...formation. For those shots where propagation was observed at pressures above 550 Pa, Faraday cuD traces show a loss of the beam tail. ’II I UNCLASSIFIED...the drift tube. At high pressures, propagation was limited by a lack of a stable pinch equilibrium, with losses predominantly at the beam tail. At the

  17. Electronically controlled optical beam-steering by an active phased array of metallic nanoantennas.

    PubMed

    DeRose, C T; Kekatpure, R D; Trotter, D C; Starbuck, A; Wendt, J R; Yaacobi, A; Watts, M R; Chettiar, U; Engheta, N; Davids, P S

    2013-02-25

    An optical phased array of nanoantenna fabricated in a CMOS compatible silicon photonics process is presented. The optical phased array is fed by low loss silicon waveguides with integrated ohmic thermo-optic phase shifters capable of 2π phase shift with ∼ 15 mW of applied electrical power. By controlling the electrical power to the individual integrated phase shifters fixed wavelength steering of the beam emitted normal to the surface of the wafer of 8° is demonstrated for 1 × 8 phased arrays with periods of both 6 and 9 μm.

  18. Grid-controlled extraction of pulsed ion beams

    NASA Astrophysics Data System (ADS)

    Humphries, S., Jr.; Burkhart, C.; Coffey, S.; Cooper, G.; Len, L. K.; Savage, M.; Woodall, D. M.; Rutkowski, H.; Oona, H.; Shurter, R.

    1986-03-01

    Experimental results are presented on a method for extracting well-focused ion beams from plasma sources with time-varying properties. An electrostatic grid was used to stop the flow of plasma electrons so that only ions entered the extraction gap. In this case, ion flow in the gap was controlled by space-charge effects as it would be with a thermionic ion source. Constant extracted current was observed even with large variations of source flux. An insulator spark source and a metal-vapor vacuum arc were used to generate pulsed ion beams. With a hydrocarbon spark, current densities of 44 mA/cm2 were achieved at 20-kV extractor voltage for an 8-μs pulse. With an aluminum-vapor arc, a current density of 15 mA/cm2 (0.3 A total) was measured for a 50-μs pulse.

  19. Experimental Demonstration of a Controllable Electrostatic Molecular Beam Splitter

    SciTech Connect

    Deng Lianzhong; Liang Yan; Gu Zhenxing; Hou Shunyong; Li Shengqiang; Xia Yong; Yin Jianping

    2011-04-08

    We experimentally demonstrate a controllable electrostatic beam splitter for guided ND{sub 3} molecules with a single Y-shaped charged wire and a homogeneous bias field generated by a charged metallic parallel-plate capacitor. We study the dependences of the splitting ratio R of the guided ND{sub 3} beam and its relative guiding efficiency {eta} on the voltage difference between two output arms of the splitter. The influences of the molecular velocity v and the cutting position L on the splitting ratio R are investigated as well, and the guiding and splitting dynamic processes of cold molecules are simulated. Our study shows that the splitting ratio R of our splitter can be conveniently adjusted from 10% to 90% by changing {Delta}U from -6 kV to +6 kV, and the simulated results are consistent with our experimental ones.

  20. Pointing and Jitter Control for the USNA Multi-Beam Combining System

    DTIC Science & Technology

    2013-05-10

    adaptive controller and other controllers to the multiple-beam combining system in a multiple-input, multiple-output feedback control environment...block contained all of the controllers for this system and was masked. The mask allowed the user to choose which PSM provided feedback to each mirror... control of each beam. Beams were controlled using feedback from PSMs and classical PI control to set performance metrics for the system . PI

  1. A randomized controlled trial of financial incentives for weight loss

    PubMed Central

    Volpp, Kevin G.; John, Leslie K; Troxel, Andrea B; Norton, Laurie; Fassbender, Jennifer; Loewenstein, George

    2012-01-01

    Context Identifying effective strategies for treating obesity is both a clinical challenge and a public health priority due to the health consequences of obesity. Objective To determine whether common decision errors identified by behavioral economists such as prospect theory, loss aversion, and regret could be used to design an effective weight loss intervention. Design 3-arm randomized controlled trial in which participants were randomized to either usual care (weigh ins once a month) or one of two financial incentives arms. One incentive arm used deposit contracts in which participants put their own money at risk (matched 1:1 by the study) which they would lose if they failed to lose weight. The second used lottery-based incentives in which participants who met the weight loss target had each day a 1 in 5 chance of winning a small reward ($10) and a 1 in 100 chance of winning a large reward ($100). All participants were given a weight loss goal of 1 pound per week for 16 weeks, and results were analyzed using intention-to-treat analysis of variance models. Setting Philadelphia Veterans Affairs Medical Center. Patients 57 patients with BMIs between 30-40 aged between 30 and 70, with no contraindications for study participation. Main Outcome Measures Weight loss after 16 weeks. Results Participants in both incentive groups lost significantly more weight than participants in the control group (3.9 pounds); (Lottery = 13.1 lbs; p-value for lottery vs. control .014; deposit contract = 14.0 lbs, p-value vs. control .003). 47.4% of deposit contract participants and 52.6% of lottery arm participants met the 16-pound weight loss goal compared to 10.5% in the control group (p-value 0.014.). By the end of 7 months, substantial amounts of weight were regained; however, incentive participants weighed significantly less than they did at the study start whereas controls did not. Low lost to follow-up rates (7.0%) during the weight loss phase of the study suggest that both

  2. Collimation system for beam loss localization with slip stacking injection in the Fermilab Main Injector

    SciTech Connect

    Brown, Bruce C.; /Fermilab

    2008-09-01

    Slip stacking injection for high intensity operation of the Fermilab Main Injector produces a small fraction of beam which is not captured in buckets and accelerated. A collimation system has been implemented with a thin primary collimator to define the momentum aperture at which this beam is lost and four massive secondary collimators to capture the scattered beam. The secondary collimators define tight apertures and thereby capture a fraction of other lost beam. The system was installed in 2007 with commissioning continuing in 2008. The collimation system will be described including simulation, design, installation, and commissioning. Successful operation and operational limitations will be described.

  3. Stripper-foil scan studies of the first-turn beam loss mechanism in the LAMPF proton storage ring (PSR)

    SciTech Connect

    Hutson, R.: Fitzgerald, D.; Frankle, S.; Macek, R.; Plum, M.; Wilkinson, C.

    1993-01-01

    First-turn beam losses in the LAMPF Proton Storage Ring were measured as a function of the left-right position of the carbon foil used to strip neutral hydrogen atoms to H[sup +] for proton injection into the PSR. Two foil thicknesses, 200 and 300 [mu]g/cm[sup 2], were tested. Results indicated that first-turn loss is caused predominately by magnetic field stripping of a small fraction of the H[sub 0] atoms that pass through the stripper foil without being stripped to protons, and the results were not consistent with a mechanism involving protons originating from atoms in the halo of the neutral beam incident on the stripper foil.

  4. Stripper-foil scan studies of the first-turn beam loss mechanism in the LAMPF proton storage ring (PSR)

    SciTech Connect

    Hutson, R.: Fitzgerald, D.; Frankle, S.; Macek, R.; Plum, M.; Wilkinson, C.

    1993-06-01

    First-turn beam losses in the LAMPF Proton Storage Ring were measured as a function of the left-right position of the carbon foil used to strip neutral hydrogen atoms to H{sup +} for proton injection into the PSR. Two foil thicknesses, 200 and 300 {mu}g/cm{sup 2}, were tested. Results indicated that first-turn loss is caused predominately by magnetic field stripping of a small fraction of the H{sub 0} atoms that pass through the stripper foil without being stripped to protons, and the results were not consistent with a mechanism involving protons originating from atoms in the halo of the neutral beam incident on the stripper foil.

  5. Quality control and patient dosimetry in dental cone beam CT.

    PubMed

    Vassileva, J; Stoyanov, D

    2010-01-01

    This paper presents the initial experience in performing quality control and patient dose measurements in a cone beam computed tomography (CT) scanner (ILUMA Ultra, IMTEC Imaging, USA) for oral and maxillofacial radiology. The X-ray tube and the generator were tested first, including the kVp accuracy and precision, and the half-value layer (HVL). The following tests specific for panoramic dental systems were also performed: tube output, beam size and beam alignment to the detector. The tests specific for CT included measurements of noise and CT numbers in water and in air, as well as the homogeneity of CT numbers. The most appropriate dose quantity was found to be the air kerma-area product (KAP) measured with a KAP-metre installed at the tube exit. KAP values were found to vary from 110 to 185 microGy m(2) for available adult protocols and to be 54 microGy m(2) for the paediatric protocol. The effective dose calculated with the software PCXMC (STUK, Finland) was 0.05 mSv for children and 0.09-0.16 mSv for adults.

  6. BEAM-LOSS DRIVEN DESIGN OPTIMIZATION FOR THE SPALLATION NEUTRON SOURCE (SNS) RING.

    SciTech Connect

    WEI,J.; BEEBE-WANG,J.; BLASKIEWICZ,M.; CAMERON,P.; DANBY,G.; GARDNER,C.J.; JACKSON,J.; LEE,Y.Y.; LUDEWIG,H.; MALITSKY,N.; RAPARIA,D.; TSOUPAS,N.; WENG,W.T.; ZHANG,S.Y.

    1999-03-29

    This paper summarizes three-stage design optimization for the Spallation Neutron Source (SNS) ring: linear machine design (lattice, aperture, injection, magnet field errors and misalignment), beam core manipulation (painting, space charge, instabilities, RF requirements), and beam halo consideration (collimation, envelope variation, e-p issues etc.).

  7. Energy Loss of a High Charge Bunched Electron Beam in Plasma: Nonlinear Plasma Response and Linear Scaling

    NASA Astrophysics Data System (ADS)

    Rosenzweig, J. B.; Barov, N.; Thompson, M. C.; Yoder, R.

    2002-12-01

    There has been much experimental and theoretical interest in blowout regime of plasma wakefield acceleration (PWFA), which features ultra-high accelerating fields, linear transverse focusing forces, and nonlinear plasma motion. Using an exact analysis, we examine here a fundamental limit of nonlinear PWFA excitation, by an infinitesimally short, relativistic electron beam. The beam energy loss in this case is shown to be linear in charge even for nonlinear plasma response, where a normalized, unitless charge exceeds unity, and relativistic plasma effects become important or dominant. The physical bases for this persistence of linear response are pointed out. As a byproduct of our analysis, we re-examine the issue of field divergence as the point-charge limit is approached, suggesting an important modification of commonly held views of evading unphysical energy loss. Deviations from linear behavior are investigated using simulations with finite length beams. The peak accelerating field in the plasma wave excited behind a finite-length beam is also examined, with the artifact of wave spiking adding to the apparent persistence of linear scaling of the peak field amplitude well into the nonlinear regime. On the other hand, at large enough normalized charge, linear scaling of fields collapses, with serious consequences for plasma wave excitation efficiency. The dramatic implications of these results for observing the collapse of linear scaling in planned experiments are discussed.

  8. On-Line Loss of Control Detection Using Wavelets

    NASA Technical Reports Server (NTRS)

    Brenner, Martin J. (Technical Monitor); Thompson, Peter M.; Klyde, David H.; Bachelder, Edward N.; Rosenthal, Theodore J.

    2005-01-01

    Wavelet transforms are used for on-line detection of aircraft loss of control. Wavelet transforms are compared with Fourier transform methods and shown to more rapidly detect changes in the vehicle dynamics. This faster response is due to a time window that decreases in length as the frequency increases. New wavelets are defined that further decrease the detection time by skewing the shape of the envelope. The wavelets are used for power spectrum and transfer function estimation. Smoothing is used to tradeoff the variance of the estimate with detection time. Wavelets are also used as front-end to the eigensystem reconstruction algorithm. Stability metrics are estimated from the frequency response and models, and it is these metrics that are used for loss of control detection. A Matlab toolbox was developed for post-processing simulation and flight data using the wavelet analysis methods. A subset of these methods was implemented in real time and named the Loss of Control Analysis Tool Set or LOCATS. A manual control experiment was conducted using a hardware-in-the-loop simulator for a large transport aircraft, in which the real time performance of LOCATS was demonstrated. The next step is to use these wavelet analysis tools for flight test support.

  9. A novel digitization scheme with FPGA-base TDC for beam loss monitors operating at cryogenic temperature

    SciTech Connect

    Wu, Jinyuan; Warner, Arden; /Fermilab

    2011-11-01

    Recycling integrators are common current-to-frequency converting circuits for measurements of low current such as that produced by Fermilab's cryogenic ionization chambers. In typical digitization/readout schemes, a counter is utilized to accumulate the number of pulses generated by the recycling integrator to adequately digitize the total charge. In order to calculate current with reasonable resolution (e.g., 7-8 bits), hundreds of pulses must be accumulated which corresponds to a long sampling period, i.e., a very low sampling rate. In our new scheme, an FPGA-based Time-to-Digital Convertor (TDC) is utilized to measure the time intervals between the pulses output from the recycling integrator. Using this method, a sample point of the current can be made with good resolution (>10 bits) for each pulse. This effectively increases the sampling rates by hundreds of times for the same recycling integrator front-end electronics. This scheme provides a fast response to the beams loss and is potentially suitable for accelerator protection applications. Moreover, the method is also self-zero-suppressed, i.e., it produces more data when the beam loss is high while it produces significantly less data when the beam loss is low.

  10. Acoustic beam control in biomimetic projector via velocity gradient

    NASA Astrophysics Data System (ADS)

    Gao, Xiaowei; Zhang, Yu; Cao, Wenwu; Dong, Erqian; Song, Zhongchang; Li, Songhai; Tang, Liguo; Zhang, Sai

    2016-07-01

    A biomimetic projector (BioP) based on computerized tomography of pygmy sperm whale's biosonar system has been designed using gradient-index (GRIN) material. The directivity of this BioP device was investigated as function of frequency and the velocity gradient of the GRIN material. A strong beam control over a broad bandwidth at the subwavelength scale has been achieved. Compared with a bare subwavelength source, the main lobe pressure of the BioP is about five times as high and the angular resolution is one order of magnitude better. Our results indicate that this BioP has excellent application potential in miniaturized underwater sonars.

  11. Acoustic beam control in biomimetic projector via velocity gradient

    SciTech Connect

    Gao, Xiaowei; Dong, Erqian; Song, Zhongchang; Zhang, Yu E-mail: dzk@psu.edu; Tang, Liguo; Cao, Wenwu E-mail: dzk@psu.edu; Li, Songhai; Zhang, Sai

    2016-07-04

    A biomimetic projector (BioP) based on computerized tomography of pygmy sperm whale's biosonar system has been designed using gradient-index (GRIN) material. The directivity of this BioP device was investigated as function of frequency and the velocity gradient of the GRIN material. A strong beam control over a broad bandwidth at the subwavelength scale has been achieved. Compared with a bare subwavelength source, the main lobe pressure of the BioP is about five times as high and the angular resolution is one order of magnitude better. Our results indicate that this BioP has excellent application potential in miniaturized underwater sonars.

  12. Adaptive beam shaping by controlled thermal lensing in optical elements.

    PubMed

    Arain, Muzammil A; Quetschke, Volker; Gleason, Joseph; Williams, Luke F; Rakhmanov, Malik; Lee, Jinho; Cruz, Rachel J; Mueller, Guido; Tanner, D B; Reitze, David H

    2007-04-20

    We describe an adaptive optical system for use as a tunable focusing element. The system provides adaptive beam shaping via controlled thermal lensing in the optical elements. The system is agile, remotely controllable, touch free, and vacuum compatible; it offers a wide dynamic range, aberration-free focal length tuning, and can provide both positive and negative lensing effects. Focusing is obtained through dynamic heating of an optical element by an external pump beam. The system is especially suitable for use in interferometric gravitational wave interferometers employing high laser power, allowing for in situ control of the laser modal properties and compensation for thermal lensing of the primary laser. Using CO(2) laser heating of fused-silica substrates, we demonstrate a focal length variable from infinity to 4.0 m, with a slope of 0.082 diopter/W of absorbed heat. For on-axis operation, no higher-order modes are introduced by the adaptive optical element. Theoretical modeling of the induced optical path change and predicted thermal lens agrees well with measurement.

  13. Optical and control modeling for adaptive beam-combining experiments

    SciTech Connect

    Gruetzner, J.K.; Tucker, S.D.; Neal, D.R.; Bentley, A.E.; Simmons-Potter, K.

    1995-08-01

    The development of modeling algorithms for adaptive optics systems is important for evaluating both performance and design parameters prior to system construction. Two of the most critical subsystems to be modeled are the binary optic design and the adaptive control system. Since these two are intimately related, it is beneficial to model them simultaneously. Optic modeling techniques have some significant limitations. Diffraction effects directly limit the utility of geometrical ray-tracing models, and transform techniques such as the fast fourier transform can be both cumbersome and memory intensive. The authors have developed a hybrid system incorporating elements of both ray-tracing and fourier transform techniques. In this paper they present an analytical model of wavefront propagation through a binary optic lens system developed and implemented at Sandia. This model is unique in that it solves the transfer function for each portion of a diffractive optic analytically. The overall performance is obtained by a linear superposition of each result. The model has been successfully used in the design of a wide range of binary optics, including an adaptive optic for a beam combining system consisting of an array of rectangular mirrors, each controllable in tip/tilt and piston. Wavefront sensing and the control models for a beam combining system have been integrated and used to predict overall systems performance. Applicability of the model for design purposes is demonstrated with several lens designs through a comparison of model predictions with actual adaptive optics results.

  14. Multiple beam phased array for Space Station Control Zone Communications

    NASA Astrophysics Data System (ADS)

    Halsema, P. B.

    The Space Station Communications Control Zone is a disk shaped region 40 nautical miles in diameter and 10 nautical miles thick centered about the Space Station. It is estimated that 6 simultaneous Multiple Access (MA) channels will be required to satisfy the projected communications needs within this zone. These channels will be used to communicate with MA users located anywhere within the Control Zone. This paper details the tradeoffs and design implementation of a multiple beam integrated phased array to provide antenna coverage of the Control Zone. The array is a compact, modular assembly using Gallium Arsenide circuits, microstrip elements, and advanced packaging techniques. This results in a small, reliable antenna system capable of meeting the projected Space Station requirements and flexible enough to grow and evolve as the Space Station communications needs develop.

  15. Validation test for climate control on air-loss supports.

    PubMed

    Reger, S I; Adams, T C; Maklebust, J A; Sahgal, V

    2001-05-01

    To develop a simple, reproducible validation test protocol for classification of air-loss support systems. Simultaneous experimental measurement of moisture loss and temperature reduction at the air-loss support surface-human body equivalent interface from a sweating human skin analogue. A hospital department of physical medicine and rehabilitation. These 3 manufacturers contributed 14 support surfaces. Test support surfaces and a standard foam mattress were placed on a hospital bed. Water was circulated to a loading gauge, placed on a dry moisture reservoir, and connected to a water bath to keep the interface at 37 degrees +/- 0.5 degrees C. The loading gauge and support surface was adjusted 23cm below the water bath level and the air flow through the interface initiated. After the dry moisture reservoir came to temperature equilibrium for 30 minutes, it was replaced with a wet one that was saturated with 36g of saline. The temperature change and evaporation rate were recorded throughout a 90-minute test period. Temperature of support surface interface and evaporation rate. Clustered data from temperature reduction and standardized rate of moisture loss yielded 3 groups of support surfaces in categories of no air loss (control), low air loss (LAL), and high air loss. The mean values of the characteristic temperature reduction and rate of moisture loss differed significantly between the groups. By multiple comparisons with Bonferroni's adjustment, the group means differed significantly for average temperature reduction (p <.017) and for standardized rate of moisture loss (p =.0001). The measured temperature change at any instant of time reflected the effect of evaporation and the opposing effect of thermal conductivity. Measurements of support interface climate change allowed for selective grouping of LAL surfaces according to rate of moisture evaporation and the resulting temperature reduction. Neither temperature change nor evaporation rate alone was sufficient

  16. Energy Loss of High Intensity Focused Proton Beams Penetrating Metal Foils

    NASA Astrophysics Data System (ADS)

    McGuffey, C.; Qiao, B.; Kim, J.; Beg, F. N.; Wei, M. S.; Evans, M.; Fitzsimmons, P.; Stephens, R. B.; Chen, S. N.; Fuchs, J.; Nilson, P. M.; Canning, D.; Mastrosimone, D.; Foord, M. E.

    2014-10-01

    Shortpulse-laser-driven intense ion beams are appealing for applications in probing and creating high energy density plasmas. Such a beam isochorically heats and rapidly ionizes any target it enters into warm dense matter with uncertain transport and stopping properties. Here we present experimental measurements taken with the 1.25 kJ, 10 ps OMEGA EP BL shortpulse laser of the proton and carbon spectra after passing through metal foils. The laser irradiated spherically curved C targets with intensity 4×1018 W/cm2, producing proton beams with 3 MeV slope temperature and a sharp low energy cutoff at 5 MeV which has not been observed on lower energy, shorter pulse intense lasers. The beam either diverged freely or was focused to estimated 1016 p +/cm2 ps by a surrounding structure before entering the metal foils (Al or Ag and a Cu tracer layer). The proton and ion spectra were altered by the foil depending on material and whether or not the beam was focused. Transverse proton radiography probed the target with ps temporal and 10 micron spatial resolution, indicating an electrostatic field on the foil may also have affected the beam. We present complementary particle-in-cell simulations of the beam generation and transport to the foils. This work was supported by the DOE/NNSA National Laser User Facility program, Contract DE-SC0001265.

  17. Beam control and diagnostic functions in the NIF transport spatial filter

    SciTech Connect

    Holdener, F.R.; Ables, E.; Bliss, E.S.

    1996-10-01

    Beam control and diagnostic systems are required to align the National Ignition Facility (NIF) laser prior to a shot as well as to provide diagnostics on 192 beam lines at shot time. A design that allows each beam`s large spatial filter lenses to also serve as objective lenses for beam control and diagnostic sensor packages helps to accomplish the task at a reasonable cost. However, this approach also causes a high concentration of small optics near the pinhole plane of the transport spatial filter (TSF) at the output of each beam. This paper describes the optomechanical design in and near the central vacuum vessel of the TSF.

  18. Active Position Control of a Flexible Smart Beam Using Internal Model Control

    NASA Astrophysics Data System (ADS)

    LEE, Y.-S.; ELLIOTT, S. J.

    2001-05-01

    The problem of controlling the position at the tip of a flexible cantilever beam to follow a command signal is considered, by using a pair of piezoelectric actuators at the clamped end. The beam is lightly damped and so the natural transient response is rather long, and also since the sensor and actuator are not collocated, the plant response is non-minimum phase. Two control strategies were investigated. The first involved conventional PID control in which the feedback gains were adjusted to give the fastest closed-loop response to a step input. The second control strategy was based on an internal model control (IMC) architecture. The control filter in the IMC controller was a digital FIR device designed to minimize the expectation of the mean square tracking error. In practice, such smart beams could be exposed to temperature fluctuations and changes in geometry. The effect of these variations on the stability was studied and it is shown that the need for robustness to such variations leads to a limitation in the performance of an IMC controller. The improvement in the stability robustness by incorporating control effort weighting into the cost function being minimized was investigated, as was the incorporation of modelling delay in the design of the IMC control filter. The IMC controller designed for the beam was found to have much reduced settling times to a step input compared with those of the PID controller while maintaining good robustness to changes in temperature. However, the extremely low damping of the experimental beam made it difficult to implement an accurate plant model in practice.

  19. Greater weight loss among men participating in a commercial weight loss program: a pooled analysis of 2 randomized controlled trials.

    PubMed

    Barraj, Leila M; Murphy, Mary M; Heshka, Stanley; Katz, David L

    2014-02-01

    Being overweight and obese are significant health concerns for men and women, yet despite comparable needs for effective weight loss and maintenance strategies, little is known about the success of commercial weight loss programs in men. This study tests the hypothesis that men participating in a commercial weight loss program (Weight Watchers) had significantly greater weight loss than men receiving limited support from health professionals for weight loss (controls). A pooled analysis of weight loss and related physiologic parameter data from 2 randomized clinical trials was conducted. After 12 months, analysis of covariance tests showed that men in the commercial program group (n = 85) lost significantly more weight (P < .01) than men in the control group (n = 84); similar significant differences were observed for body mass index and waist circumference. These results suggest that participation in a commercial weight loss program may be a more effective means to lose weight and maintain weight loss.

  20. Energy loss in intergalactic pair beams: Particle-in-cell simulation

    NASA Astrophysics Data System (ADS)

    Kempf, A.; Kilian, P.; Spanier, F.

    2016-01-01

    Aims: The change in the distribution function of electron-positron pair beams determines whether GeV photons can be produced as secondary radiation from TeV photons. We will discuss the instabilities driven by pair beams. Methods: The system of a thermal proton-electron plasma and the electron-positron beam is collision free. We have, therefore, used the particle-in-cell simulation approach. It was necessary to alter the physical parameters, but the ordering of growth rates has been retained. Results: We were able to show that plasma instabilities can be recovered in particle-in-cell simulations, but their effect on the pair distribution function is negligible for the beam-background energy density ratios typically found in blazars.

  1. Estimation of propagation losses for infrared laser beam in turbulent atmosphere

    NASA Astrophysics Data System (ADS)

    Zaponov, A. E.; Sakharov, M. V.

    2016-11-01

    In present work, the radiation propagation in atmosphere from laser source to the receiver is considered by taking into account deviations of optical beam due to turbulence. The photon flux density on the receiver has been evaluated.

  2. Spin-Controlled Multiple Pencil Beams and Vortex Beams with Different Polarizations Generated by Pancharatnam-Berry Coding Metasurfaces.

    PubMed

    Zhang, Lei; Liu, Shuo; Li, Lianlin; Cui, Tie Jun

    2017-10-03

    We propose to design coding metasurfaces based on the Pancharatnam-Berry (PB) phase. The proposed PB coding metasurface could control circularly polarized components of incident waves, by encoding geometric phase into the orientation angle of coding particles to generate 1-bit and multibit phase responses. We perform digital convolution operations on scattering patterns of the PB coding metasurface to reach flexible controls of the circularly polarized waves, forming spin-controlled multiple beams with different polarizations in free space, such as pencil beams and vortex beams carrying orbital angular momentum. Both numerical and experimental results demonstrate the excellent performance of the PB coding metasurface, which opens a pathway to novel types of multibeam generations and provides an effective way to expand the beam coverage for wireless communication applications.

  3. Ion beam-induced hydroxylation controls molybdenum disulfide growth

    NASA Astrophysics Data System (ADS)

    Bartolucci, Stephen F.; Kaplan, Daniel; Maurer, Joshua A.

    2017-06-01

    2D materials, such as graphene and transition metal dichalcogenides, are a promising class of nanomaterials for next generation electronics, photovoltaics, electrocatalysts, sensors, and optoelectronic devices. Molybdenum disulfide (MoS2) is of particular interest due to its direct bandgap in the visible spectrum, high electron mobility, and chemical stability. Here, we demonstrate that alterations in the density of surface hydroxyl groups on silicon dioxide substrates can control nucleation and growth in molybdenum disulfide thin films produced by atmospheric-pressure chemical vapor deposition. The extent of MoS2 nucleation is linearly correlated to the density of surface hydroxyl groups. Controlling the density of surface hydroxyl groups on the initial substrate provides a method of growing patterned molybdenum disulfide. Furthermore, we establish that the surface density of hydroxyl groups on silicon dioxide (SiO2) is altered using conventional gallium focused ion beam (FIB) patterning. Upon gallium-ion beam exposure, the number of hydroxyl groups generated on the surface is directly proportional to the ion dosage. This work establishes a means of patterning large-area monolayer MoS2 on silicon dioxide substrates, which is a critical step for realizing applications in imaging, catalysis, biosensing, chemical detection, electronics and optoelectronics.

  4. Transmission losses in optical qubits for controlled teleportation

    NASA Astrophysics Data System (ADS)

    Medina, I.; Semião, F. L.

    2017-10-01

    In this work, we investigate the controlled teleportation protocol using optical qubits within the single-rail logic. The protocol makes use of an entangled tripartite state shared by the controller and two further parties (users) who will perform standard teleportation. The goal of the protocol is to guarantee that the teleportation is successful only with the permission of the controller. Optical qubits based on either superpositions of vacuum and single-photon states or superposition of coherent states are employed here to encode a tripartite maximal slice state upon which the protocol is based. We compare the performances of these two encodings under losses which are present when the qubits are guided through an optical fiber to the users. Finally, we investigate the non-locality of the shared tripartite state to see whether or not it impacts the efficiency of the protocol.

  5. An Agile Beam Transmit Array Using Coupled Oscillator Phase Control

    NASA Technical Reports Server (NTRS)

    Pogorzelski, Ronald S.; Scaramastra, Rocco P.; Huang, John; Beckon, Robert J.; Petree, Steve M.; Chavez, Cosme

    1993-01-01

    A few years ago York and colleagues suggested that injection locking of voltage controlled oscillators could be used to implement beam steering in a phased array [I]. The scheme makes use of the fact that when an oscillator is injection locked to an external signal, the phase difference between the output of the oscillator and the injection signal is governed by the difference between the injection frequency and the free running frequency of the oscillator (the frequency to which the oscillator is tuned). Thus, if voltage controlled oscillators (VCOs) are used, this phase difference is controlled by an applied voltage. Now, if a set of such oscillators are coupled to nearest neighbors, they can be made to mutually injection lock and oscillate as an ensemble. If they are all tuned to the same frequency, they will all oscillate in phase. Thus, if the outputs are connected to radiating elements forming a linear array, the antenna will radiate normal to the line of elements. Scanning is accomplished by antisymmetrically detuning the end oscillators in the array by application of a pair of appropriate voltages to their tuning ports. This results in a linear phase progression across the array which is just the phasing required to scan the beam. The scan angle is determined by the degree of detuning. We have constructed a seven element one dimensional agile beam array at S-band based on the above principle. Although, a few such arrays have been built in the past, this array possesses two unique features. First, the VCO MMICs have buffer amplifiers which isolate the output from the tuning circuit, and second, the oscillators are weakly coupled to each other at their resonant circuits rather than their outputs. This results in a convenient isolation between the oscillator array design and the radiating aperture design. An important parameter in the design is the so called coupling phase which determines the phase shift of the signals passing from one oscillator to its

  6. Summary report on beam and radiation generation, monitoring and control (working group 6).

    SciTech Connect

    Power, J. G.; Gordon, D. F.; High Energy Physics; Naval Research Lab.

    2009-01-01

    The discussions of the working group on beam and radiation generation, monitoring, and control (working group 6) at the 2008 advanced accelerator concepts workshop are summarized. The discussions concerned electron injectors, phase space manipulation, beam diagnostics, pulse train generation, intense beam physics, and radiation generation.

  7. Controls on nitrogen loss processes in Chesapeake Bay sediments.

    PubMed

    Babbin, Andrew R; Ward, Bess B

    2013-05-07

    The flux of fixed nitrogen into the marine environment is increasing as a direct result of anthropogenic nitrogen loading, but the controls on the mechanisms responsible for the removal of this increased supply are not well constrained. The fate of fixed nitrogen via mineralization and nitrogen loss processes was investigated by simulating a settling event of organic matter (OM) in mesocosms containing Chesapeake Bay sediments. Microorganisms rapidly transformed the OM during the course of a seven week incubation ultimately leading to nitrogen loss via denitrification and anaerobic ammonium oxidation (anammox). The microbial community responded quickly to the OM amendment suggesting that estuarine sediments can buffer the natural system against sudden injections of organic material. Two different levels of organic matter amendment resulted in different magnitudes of ammonium and nitrite accumulation during the incubation, but both treatments exhibited the same overall sequence of dissolved inorganic nitrogen (DIN) accumulation and removal. An inverse least-squares analysis coupled to a Michaelis-Menten prognostic model was conducted to estimate rates of nitrogen transformations from the measured DIN concentrations. Whereas the rates were higher at higher OM, the percentage of nitrogen lost via anammox was constant at 44.3 ± 0.3%. The stoichiometry of organic matter and the allochthonous supply of ammonium determined the relative contribution of anammox and denitrification to overall nitrogen loss. Further, in situ thermodynamics based on measured concentrations suggested that the energy favorability of denitrification and anammox plays a role in determining the timing of these processes as OM remineralization progresses.

  8. Feedback control of multimode magnetohydrodynamic instabilities via neutral beams

    SciTech Connect

    Sen, A.K.

    1998-08-01

    In most scenarios of confinement degradation due to MHD (magnetohydrodynamic) fluctuations in both tokamaks and reversed field pinches several MHD modes are involved. This is the motivation for the development of a multimode feedback scheme in the present paper, in contrast to the past work. The scheme is based on modal (state) feedback, where each mode is unscrambled out of the sensor signal, which is a superposition of all mode information and then individually acted upon by a unique gain and phase. Finally, all these individually processed mode signals are electronically summed and impressed on the accelerator grid of a neutral beam as a single control signal. It is shown that this process can lead to the stabilization of all unstable modes without destabilization of any stable modes, in contrast to previous feedback experiments. {copyright} {ital 1998 American Institute of Physics.}

  9. Observing Atoms at Work by Controlling Beam-Sample Interactions.

    PubMed

    Kisielowski, Christian

    2015-10-14

    Functional behavior can be initiated and captured in series of images with previously unknown details using a successful effort to effectively control beam-sample interactions in high-resolution transmission electron microscopy. The approach uses tunable electron dose rates that can be chosen to be as low as attoamperes per square-Ångstrom to delay sample degradation to an unexplored end. Dose rates can be systematically increased to stimulate and observe dynamic object responses. Observations can be made in real time with deep sub-Ångstrom resolution and single-atom sensitivity, even if radiation-sensitive matter is probed and either pressure or temperature is raised in the electron microscope.

  10. Beam position monitor readout and control in the SLC linac

    SciTech Connect

    Bogart, J.; Phinney, N.; Ross, M.; Yaffe, D.

    1985-04-01

    A beam position monitoring system has been implemented in the first third of the SLC linac which provides a complete scan of the trajectory on a single beam pulse. The data is collected from the local micro-computers and viewed with an updating display at a console or passed on to application programs. The system must operate with interlaced beams so the scans are also interlaced, providing each user with the ability to select the beam, the update rate, and the attenuation level in the digitizing hardware. In addition each user calibrates the hardware for his beam. A description of the system architecture will be presented. 6 refs., 4 figs.

  11. Simulation of multicomponent losses in electron beam melting and refining at varying scan frequencies

    SciTech Connect

    Powell, A.; Szekely, J.; Van Den Avyle, J.; Damkroger, B.

    1995-10-12

    A two-stage model is presented to describe alloy element evaporation rates from molten metal due to transient local heating by an electron beam. The first stage is a simulation of transient phenomena near the melt surface due to periodic heating by a scanning beam, the output of which is the relationship between operating parameters, surface temperature, and evaporation rate. At high scan rates, this can be done using a simple one-dimensional heat transfer model of the surface layer; at lower scan rates, a more complex three-dimensional model with fluid flow and periodic boundary conditions is necessary. The second stage couples this evaporation-surface temperature relationship with a larger steady state heat transfer and fluid flow model of an entire melting hearth or mold, in order to calculate local and total evaporation rates. Predictions are compared with experimental results from Sandia`s 310-kW electron beam melting furnace, in which evaporation rates and vapor compositions were studied in pure titanium and Ti-6%Al-4%V alloy. Evaporation rates were estimated from rate of condensation on a substrate held over the hearth, and were characterized as a function of beam power (150 and 225 kW), scan frequency (30, 115 and 450 Hz) and background pressure (10{sup {minus}3}, 10{sup {minus}4} and 10{sup {minus}5} torr).

  12. Swelling-induced and controlled curving in layered gel beams

    PubMed Central

    Lucantonio, A.; Nardinocchi, P.; Pezzulla, M.

    2014-01-01

    We describe swelling-driven curving in originally straight and non-homogeneous beams. We present and verify a structural model of swollen beams, based on a new point of view adopted to describe swelling-induced deformation processes in bilayered gel beams, that is based on the split of the swelling-induced deformation of the beam at equilibrium into two components, both depending on the elastic properties of the gel. The method allows us to: (i) determine beam stretching and curving, once assigned the characteristics of the solvent bath and of the non-homogeneous beam, and (ii) estimate the characteristics of non-homogeneous flat gel beams in such a way as to obtain, under free-swelling conditions, three-dimensional shapes. The study was pursued by means of analytical, semi-analytical and numerical tools; excellent agreement of the outcomes of the different techniques was found, thus confirming the strength of the method. PMID:25383031

  13. APT Blanket System Loss-of-Coolant Accident (LOCA) Based on Initial Conceptual Design - Case 2: with Beam Shutdown Only

    SciTech Connect

    Hamm, L.L.

    1998-10-07

    This report is one of a series of reports that document normal operation and accident simulations for the Accelerator Production of Tritium (APT) blanket heat removal system. These simulations were performed for the Preliminary Safety Analysis Report. This report documents the results of simulations of a Loss-of-Flow Accident (LOFA) where power is lost to all of the pumps that circulate water in the blanket region, the accelerator beam is shut off and neither the residual heat removal nor cavity flood systems operate.

  14. Analytic expressions for the inelastic scattering and energy loss of electron and proton beams in carbon nanotubes

    SciTech Connect

    Emfietzoglou, D.; Kyriakou, I.; Garcia-Molina, R.; Abril, I.; Kostarelos, K.

    2010-09-15

    We have determined ''effective'' Bethe coefficients and the mean excitation energy of stopping theory (I-value) for multiwalled carbon nanotubes (MWCNTs) and single-walled carbon nanotube (SWCNT) bundles based on a sum-rule constrained optical-data model energy loss function with improved asymptotic properties. Noticeable differences between MWCNTs, SWCNT bundles, and the three allotropes of carbon (diamond, graphite, glassy carbon) are found. By means of Bethe's asymptotic approximation, the inelastic scattering cross section, the electronic stopping power, and the average energy transfer to target electrons in a single inelastic collision, are calculated analytically for a broad range of electron and proton beam energies using realistic excitation parameters.

  15. Beam losses from ultra-peripheral nuclear collisions between Pb ions in the Large Hadron Collider and their alleviation

    SciTech Connect

    Bruce, R.; Bocian, D.; Gilardoni, S.; Jowett, J.M.; /CERN

    2009-08-01

    Electromagnetic interactions between colliding heavy ions at the Large Hadron Collider (LHC) at CERN will give rise to localized beam losses that may quench superconducting magnets, apart from contributing significantly to the luminosity decay. To quantify their impact on the operation of the collider, we have used a three-step simulation approach, which consists of optical tracking, a Monte-Carlo shower simulation and a thermal network model of the heat flow inside a magnet. We present simulation results for the case of {sup 208}Pb{sup 82+} ion operation in the LHC, with focus on the alice interaction region, and show that the expected heat load during nominal {sup 208}Pb{sup 82+} operation is 40% above the quench level. This limits the maximum achievable luminosity. Furthermore, we discuss methods of monitoring the losses and possible ways to alleviate their effect.

  16. Fast beam steering with full polarization control using a galvanometric optical scanner and polarization controller.

    PubMed

    Jofre, M; Anzolin, G; Steinlechner, F; Oliverio, N; Torres, J P; Pruneri, V; Mitchell, M W

    2012-05-21

    Optical beam steering is a key element in many industrial and scientific applications like in material processing, information technologies, medical imaging and laser display. Even though galvanometer-based scanners offer flexibility, speed and accuracy at a relatively low cost, they still lack the necessary control over the polarization required for certain applications. We report on the development of a polarization steerable system assembled with a fiber polarization controller and a galvanometric scanner, both controlled by a digital signal processor board. The system implements control of the polarization decoupled from the pointing direction through a feed-forward control scheme. This enables to direct optical beams to a desired direction without affecting its initial polarization state. When considering the full working field of view, we are able to compensate polarization angle errors larger than 0.2 rad, in a temporal window of less than ∼ 20 ms. Given the unification of components to fully control any polarization state while steering an optical beam, the proposed system is potentially integrable and robust.

  17. Residual stress control by ion beam assisted deposition

    SciTech Connect

    Was, G.S.; Jones, J.W.; Parfitt, L.; Kalnas, C.E.; Goldiner, M.

    1996-12-31

    The origin of residual stresses were studied in both crystalline metallic films and amorphous oxide films made by ion beam assisted deposition (IBAD). Monolithic films of Al{sub 2}O{sub 3} were deposited during bombardment by Ne, Ar or Kr over a narrow range of energies, E, and a wide range of ion-to-atom arrival rate ratios, R and were characterized in terms of composition, thickness, density, crystallinity, microstructure and residual stress. The stress was a strong function of ion beam parameters and gas content and compares to the behavior of other amorphous compounds such as MoSi{sub x} and WSi{sub 2.2}. With increasing normalized energy (eV/atom), residual stress in crystalline metallic films (Mo, W) increases in the tensile direction before reversing and becoming compressive at high normalized energy. The origin of the stress is most likely due to densification or interstitial generation. Residual stress in amorphous films (Al{sub 2}O{sub 3}, MoSi{sub x} and WSi{sub 2.2}) is initially tensile and monotonically decreases into the compressive region with increasing normalized energy. The amorphous films also incorporate substantially more gas than crystalline films and in the case of Al{sub 2}O{sub 3} are characterized by a high density of voids. Stress due to gas pressure in existing voids explains neither the functional dependence on gas content nor the magnitude of the observed stress. A more likely explanation for the behavior of stress is gas incorporation into the matrix, where the amount of incorporated gas is controlled by trapping.

  18. Advanced control of neutral beam injected power in DIII-D

    DOE PAGES

    Pawley, Carl J.; Crowley, Brendan J.; Pace, David C.; ...

    2017-03-23

    In the DIII-D tokamak, one of the most powerful techniques to control the density, temperature and plasma rotation is by eight independently modulated neutral beam sources with a total power of 20 MW. The rapid modulation requires a high degree of reproducibility and precise control of the ion source plasma and beam acceleration voltage. Recent changes have been made to the controls to provide a new capability to smoothly vary the beam current and beam voltage during a discharge, while maintaining the modulation capability. The ion source plasma inside the arc chamber is controlled through feedback from the Langmuir probesmore » measuring plasma density near the extraction end. To provide the new capability, the plasma control system (PCS) has been enabled to change the Langmuir probe set point and the beam voltage set point in real time. When the PCS varies the Langmuir set point, the plasma density is directly controlled in the arc chamber, thus changing the beam current (perveance) and power going into the tokamak. Alternately, the PCS can sweep the beam voltage set point by 20 kV or more and adjust the Langmuir probe setting to match, keeping the perveance constant and beam divergence at a minimum. This changes the beam power and average neutral particle energy, which changes deposition in the tokamak plasma. The ion separating magnetic field must accurately match the beam voltage to protect the beam line. To do this, the magnet current control accurately tracks the beam voltage set point. In conclusion, these new capabilities allow continuous in-shot variation of neutral beam ion energy to complement« less

  19. Electron beam control using shock-induced density downramp injection

    NASA Astrophysics Data System (ADS)

    Swanson, K.; Tsai, H.-E.; Barber, S.; Lehe, R.; Mao, H.-S.; Steinke, S.; van Tilborg, J.; Geddes, C. G. R.; Leemans, W. P.

    2017-03-01

    In these experiments, we improve the quality of electrons injected along a shock-induced density downramp. We demonstrate that beam ellipticity and steering are influenced by the shock front tilt, and we present simple models to explain these effects. By adjusting the shock front angle, we minimize the beam's off-axis steering and ellipticity, producing high-quality electron beams over a tunable energy range.

  20. Active vibration control of beams using filtered-velocity feedback controllers with moment pair actuators

    NASA Astrophysics Data System (ADS)

    Shin, Changjoo; Hong, Chinsuk; Jeong, Weui Bong

    2013-06-01

    In this study, filtered-velocity feedback (FVF) control is proposed to stabilize a control system with a non-collocated sensor/actuator configuration. This method is applied to actively control a clamped beam with a sensor/moment pair actuator. Since the sensor/moment pair actuator is a non-collocated configuration, the control system experiences structural instability at high frequencies. Due to the roll-off property of the FVF controller, the high frequency structural instability problem can be overcome. Due to the second-order filter characteristics of the FVF controller, similar to a low pass filter, multimode disturbances can be controlled at the modes below the cut-off frequency. To verify the performance of the controller, the FVF controller is tuned to around 2 kHz, and the structural responses are successfully reduced by numerical and experimental approaches.

  1. Input reconstruction for networked control systems subject to deception attacks and data losses on control signals

    NASA Astrophysics Data System (ADS)

    Keller, J. Y.; Chabir, K.; Sauter, D.

    2016-03-01

    State estimation of stochastic discrete-time linear systems subject to unknown inputs or constant biases has been widely studied but no work has been dedicated to the case where a disturbance switches between unknown input and constant bias. We show that such disturbance can affect a networked control system subject to deception attacks and data losses on the control signals transmitted by the controller to the plant. This paper proposes to estimate the switching disturbance from an augmented state version of the intermittent unknown input Kalman filter recently developed by the authors. Sufficient stochastic stability conditions are established when the arrival binary sequence of data losses follows a Bernoulli random process.

  2. Active Vibration Control of Elastic Beam by Means of Shape Memory Alloy Layers

    NASA Technical Reports Server (NTRS)

    Chen, Q.; Levy, C.

    1996-01-01

    The mathematical model of a flexible beam covered with shape memory alloy (SMA) layers is presented. The SMA layers are used as actuators, which are capable of changing their elastic modulus and recovery stress, thus changing the natural frequency of, and adjusting the excitation to, the vibrating beam. The frequency factor variation as a function of SMA Young's modulus, SMA layer thickness and beam thickness is discussed. Also control of the beam employing an optimal linear control law is evaluated. The control results indicate how the system reacts to various levels of excitation input through the non-homogeneous recovery shear term of the governing differential equation.

  3. Model-based beam control for illumination of remote objects, part II: laboratory testbed

    NASA Astrophysics Data System (ADS)

    Basu, Santasri; Voelz, David; Chandler, Susan M.; Lukesh, Gordon W.; Sjogren, Jon

    2004-10-01

    When a laser beam propagates through the atmosphere, it is subject to corrupting influences including mechanical vibrations, turbulence and tracker limitations. As a result, pointing errors can occur, causing loss of energy or signal at the target. Nukove Scientific Consulting has developed algorithms to estimate these pointing errors from the statistics of the return photons from the target. To prove the feasibility of this approach for real-time estimation, an analysis tool called RHINO was developed by Nukove. Associated with this effort, New Mexico State University developed a laboratory testbed, the ultimate objective being to test the estimation algorithms under controlled conditions and to stream data into RHINO to prove the feasibility of real-time operation. The present paper outlines the description of this testbed and the results obtained through RHINO when the testbed was used to test the estimation approach.

  4. Negotiating control: patients' experiences of unsuccessful weight-loss surgery.

    PubMed

    Ogden, Jane; Avenell, Sian; Ellis, Gemma

    2011-07-01

    Interviews were carried out with 10 men and women who had undergone weight-loss surgery (WLS) up to 10 years ago and felt that it had failed. Seven had had a further successful procedure. Data were analysed using Interpretative Phenomenological Analysis. Weight regain following surgery was explained in terms of either the mechanics of the operation or with participants describing ways to 'cheat' as food continued to be used for emotional regulation. Everyone spoke of how surgery neglected their mind. Following the second successful surgery, participants described changes in both their eating behaviour and cognitions emphasising how their mind had been brought 'in gear' through the investment of two invasive procedures. Transcending all accounts was the mind/body relationship and the issue of control with attributions for both failed and successful surgery shifting from the self to the surgical mechanism as the participants negotiated the pathway between self-blame and responsibility and utilised conflicting frameworks in which the mind and body were either divided or united. Whereas failed surgery is characterised by a battle for control, successful surgery involves handing control over to their restricted stomachs or considering WLS as a tool to be worked with. © 2011 Taylor & Francis

  5. Optimum shape control of flexible beams by piezo-electric actuators

    NASA Technical Reports Server (NTRS)

    Baz, A.; Poh, S.

    1987-01-01

    The utilization of piezoelectric actuators in controlling the static deformation and shape of flexible beams is examined. An optimum design procedure is presented to enable the selection of the optimal location, thickness and excitation voltage of the piezoelectric actuators in a way that would minimize the deflection of the beam to which these actuators are bonded. Numerical examples are presented to illustrate the application of the developed optimization procedure in minimizing structural deformation of beams using ceramic and polymeric piezoelectric actuators bonded to the beams with a typical bonding agent. The obtained results emphasize the importance of the devised rational produce in designing beam-actuator systems with minimal elastic distortions.

  6. High-speed reference-beam-angle control technique for holographic memory drive

    NASA Astrophysics Data System (ADS)

    Yamada, Ken-ichiro; Ogata, Takeshi; Hosaka, Makoto; Fujita, Koji; Okuyama, Atsushi

    2016-09-01

    We developed a holographic memory drive for next-generation optical memory. In this study, we present the key technology for achieving a high-speed transfer rate for reproduction, that is, a high-speed control technique for the reference beam angle. In reproduction in a holographic memory drive, there is the issue that the optimum reference beam angle during reproduction varies owing to distortion of the medium. The distortion is caused by, for example, temperature variation, beam irradiation, and moisture absorption. Therefore, a reference-beam-angle control technique to position the reference beam at the optimum angle is crucial. We developed a new optical system that generates an angle-error-signal to detect the optimum reference beam angle. To achieve the high-speed control technique using the new optical system, we developed a new control technique called adaptive final-state control (AFSC) that adds a second control input to the first one derived from conventional final-state control (FSC) at the time of angle-error-signal detection. We established an actual experimental system employing AFSC to achieve moving control between each page (Page Seek) within 300 µs. In sequential multiple Page Seeks, we were able to realize positioning to the optimum angles of the reference beam that maximize the diffracted beam intensity. We expect that applying the new control technique to the holographic memory drive will enable a giga-bit/s-class transfer rate.

  7. Broadband active vibration control of a beam using experimentally obtained impulse functions

    NASA Astrophysics Data System (ADS)

    Naghshineh, Koorosh; Gellrich, C. A.

    A flexible beam is used to demonstrate wideband active vibration control using a single sensor/actuator pair. The beam vibrations are controlled using a shaker, located between the primary vibration source and the free end of the beam such that the vibration amplitude at the free end of the beam is minimized. A PC-based controller is used to compute the control shaker driving voltage. This feedforward controller also compensates for the coupling between the control shaker and the control sensor. An overall reduction of 15 dB is achieved within the 20-1000 Hz frequency range. Not only do we observe reductions at the beam resonances, but we also observe reductions at the off-resonance frequencies. In addition to reductions in vibration amplitude at the free end of the beam, drastic reductions (10 to 15 dB) are obtained between the control shaker and the free end of the beam. Wideband control is demonstrated for two different types of disturbances (random and burst chip). This demonstration clearly shows the applicability of active control technology to active vibration control. This technology is available for multichannel, wideband applications in real-world problems for both sound and structural control.

  8. Construction and tests of an in-beam PET-like demonstrator for hadrontherapy beam ballistic control

    NASA Astrophysics Data System (ADS)

    Montarou, G.; Bony, M.; Busato, E.; Chadelas, R.; Donnarieix, D.; Force, P.; Guicheney, C.; Insa, C.; Lambert, D.; Lestand, L.; Magne, M.; Martin, F.; Millardet, C.; Nivoix, M.; Podlyski, F.; Rozes, A.

    2017-02-01

    We present the first results obtained with a detector, called Large Area Pixelized Detector (LAPD), dedicated to the study the ballistic control of the beam delivered to the patient by in-beam and real time detection of secondary particles, emitted during its irradiation in the context of hadrontherapy. These particles are 511 keV γ from the annihilation of a positron issued from the β+ emitters induced in the patient tissues along the beam path. The LAPD basic concepts are similar to a conventional PET camera. The 511 keV γ are detected and the reconstructed lines of response allow to measure the β+ activity distribution. Nevertheless, when trying to use γ from positron annihilation for the ballistic control in hadrontherapy, the large prompt γ background should be taken into account and properly rejected. First reconstruction results, obtained with a phantom filled with a high intensity FDG source at the cancer research centre of Clermont-Ferrand are shown. We also report results of measurements performed at the Heidelberg Ion-Beam Therapy Centre with one third of the detector, using proton and carbon ion beams.

  9. LASER BEAMS. CAVITIES: Coupling losses in laser cavities with a hollow rectangular or planar waveguide

    NASA Astrophysics Data System (ADS)

    Kubarev, V. V.

    1998-05-01

    The problem of the coupling losses experienced by the main waveguide mode is solved for a laser cavity formed by two mirrors with a hollow rectangular or planar waveguide between them. The optimal configurations and mirror positions are found for waveguides with different ratios of the sides. Laser cavities supporting a wide range of wavelengths are considered.

  10. A Bench Measurement of the Energy Loss of a Stored Beam to a Cavity

    SciTech Connect

    Sands, M.; Rees, John R.; /SLAC

    2005-08-08

    A rather simple electronic bench experiment is proposed for obtaining a measure of the impulse energy loss of a stored particle bunch to an rf cavity or other vacuum-chamber structure--the so-called ''cavity radiation''. The proposed method is analyzed in some detail.

  11. A Bench Measurement of the Energy Loss of a Stored Beam to a Cavity

    SciTech Connect

    Sands, M.; Rees, J.

    2016-12-19

    A rather simple electronic bench experiment is proposed for obtaining a measure of the impulse energy loss of a stored particle bunch to an rf cavity or other vacuum-chamber structure--the so-called "cavity radiation". The proposed method is analyzed in some detail.

  12. Control of Post-disruption Runaway Electron Beams in the DIII-D Tokamak

    NASA Astrophysics Data System (ADS)

    Eidietis, N. W.

    2011-10-01

    Recent experiments on DIII-D have demonstrated real-time control of post-disruption runaway electron (RE) beams, presenting the possibility for slow, controlled dissipation of the beam energy. RE beams will present a greater challenge to ITER than present tokamaks due to ITER's high RE avalanche gain constant [Nucl.Fusion 37, 1355-62 (1997)] and the difficulty repairing potential damage to its first wall. In the rare event that disruption control and mitigation schemes fail to suppress RE generation, active control of the RE beam may be an important line of defense to prevent rapid, localized deposition of RE beam energy on the first wall. Initially, sustaining a RE beam plateau requires avoiding radial collapse of the beam into the inner wall during the first 1-2 wall penetration times following the current quench (CQ). This collapse is caused by attractive induced currents in the wall and a lack of radial equilibrium with slow vertical field coils. The collapse is avoided by slewing the inner PF coils to push the RE beam off the wall while reducing the outer PF coil currents. Beam survival through this phase requires sufficient RE plateau current (IRE) and power supply slew rates to re-establish equilibrium. Following that transient period, RE beam vertical position was dynamically controlled, and stabilization was maintained in an elongated (κ <= 1 . 8) DND configuration for up 250ms. Most controlled RE beams end in a rapid vertical displacement event (VDE), indicating that the profiles evolve even as the position is controlled. Experimental radial evolution and VDE onset are shown to be consistent with theoretical calculations of controllability boundaries. However, ohmic regulation of IRE has been shown to delay VDEs to the pre-programmed ramp-down time, indicating that steady-state control may be achievable. Supported by the US DOE under DE-FC02-04ER54698.

  13. Performance of the HIMAC beam control system using multiple-energy synchrotron operation

    NASA Astrophysics Data System (ADS)

    Mizushima, K.; Furukawa, T.; Iwata, Y.; Hara, Y.; Saotome, N.; Saraya, Y.; Tansho, R.; Sato, S.; Fujimoto, T.; Shirai, T.; Noda, K.

    2017-09-01

    Multiple-energy synchrotron operation was developed to realize fast 3D scanning irradiation for carbon-ion radiotherapy. This type of operation can output various carbon-ion beams with different energies in a single synchrotron cycle. The beam control system used in this kind of operation was developed to quickly provide the beam energy and intensity required from the irradiation control system. The performance of the system was verified by experimental tests. The system could output beams of 197 different energies in 63 s. The beam intensity could be controlled for all the output beams without large ripples or overshooting. The experimental test of irradiation for prostate cancer treatment was also successfully performed, and the test results proved that our system can greatly reduce the irradiation time.

  14. Controlling tunnelling in methane loss from acetone ions by deuteration.

    PubMed

    Bodi, Andras; Baer, Tomas; Wells, Nancy K; Fakhoury, Daniel; Klecyngier, David; Kercher, James P

    2015-11-21

    Energetic acetone cations decay by methane or methyl radical loss. Although the methane-loss barrier to form the ketene cation is higher and the activation entropy is lower, it has a significant branching ratio at low energies thanks to quantum tunnelling. H-atom tunnelling can be selectively quenched and the methane-loss channel suppressed quantitatively by deuteration.

  15. BEAM CONTAINMENT SYSTEM FOR NSLS-II

    SciTech Connect

    Kramer, S.L.; Casey, W.; Job, P.K.

    2010-05-23

    The shielding design for the NSLS-II will provide adequate protection for the full injected beam loss in two periods of the ring around the injection point, but the remainder of the ring is shielded for lower losses of {le} 10% full beam. This will require a system to insure that beam losses don't exceed these levels for a period of time that could cause excessive radiation levels outside the shield walls. This beam containment system will measure, provide a level of control and alarm indication of the beam power losses along the beam path from the source (e-gun, linac) thru the injection system and the storage ring. This system will consist of collimators that will provide limits to (and potentially to measure) the beam miss-steering and control the loss points of the charge and monitors that will measure the average beam current losses along the beam path and alarm when this beam power loss exceeds the level set by the shielding specifications. This will require some new ideas in beam loss detection capability and collimation. The initial planning and R&D program will be presented.

  16. Electron beam treatment parameters for control of stored product insects

    NASA Astrophysics Data System (ADS)

    Cleghorn, D. A.; Nablo, S. V.; Ferro, D. N.; Hagstrum, D. W.

    2002-03-01

    The fluidized bed process (EBFB) has been evaluated for the disinfestation of cereal grains. The various life stages from egg to adult have been studied on the 225 kV pilot as a function of surface dose. Three of the most common pests were selected: the rice weevil ( S. oryzae), the lesser grain borer ( R. dominica) and the red flour beetle ( T. castaneum). The major challenge to this process lies in those "protected" life-stages active deeply within the endosperm of the grain kernel. The rice weevil is such an internal feeder in which the larvae develop through several molts during several weeks before pupation and adult emergence. Product velocities up to 2000 m/min have been used for infested hard winter wheat at dose levels up to 1000 Gy. Detailed depth of penetration studies at three life stages of S. oryzae larvae were conducted at 225-700 kV and demonstrated effective mortality at 400 kV×200 Gy. Mortality data are also presented for the radiation labile eggs of these insects as well as the (sterile) adults, which typically lived for several weeks before death. These results are compared with earlier 60Co gamma-ray studies on these same insects. Based upon these studies, the effectiveness of the fluidized bed process employing self-shielded electron beam equipment for insect control in wheat/rice at sub-kilogray dose levels has been demonstrated.

  17. Chaotic control of a piezomagnetoelastic beam for improved energy harvesting

    NASA Astrophysics Data System (ADS)

    Geiyer, Daniel; Kauffman, Jeffrey L.

    2015-04-01

    Linear cantilevered piezoelectric energy harvesters do not typically operate efficiently through a large span of excitation frequencies. Beam theory dictates optimum displacement at resonance excitation; however, typical environments evolve and vary over time with no clear dominant frequency. Nonlinear, non-resonant harvesting techniques have been implemented, but none so far have embraced chaotic behavior as a desirable property of the system. This work aims to benefit from chaotic phenomena by stabilizing high energy periodic orbits located within a chaotic attractor to improve operating bandwidth. Delay coordinate embedding is used to reconstruct the system states from a single time series measurement of displacement. Orbit selection, local linearization, and control perturbation are all computed from the single time series independent of an explicit system model. Although chaos in non-autonomous systems is typically associated with harmonic inputs, chaotic attractor motion can also exist throughout other excitation sources. Accelerometer data from inside a commercial vehicle and a stochastic excitation signal are used to illustrate the existence of chaos in dynamic environments, allowing such environments to be likely candidates for the proposed bandwidth improving energy harvesting technique.

  18. Control of post-disruption runaway electron beams in DIII-D

    SciTech Connect

    Eidietis, N. W.; Humphreys, D. A.; Strait, E. J.; VanZeeland, M. A.; Wesley, J. C.; Commaux, N.; Jernigan, T. C.; Hollmann, E. M.; Moyer, R. A.; Yu, J. H.

    2012-05-15

    Recent experiments in the DIII-D tokamak have demonstrated real-time control and dissipation of post-disruption runaway electron (RE) beams. In the event that disruption avoidance, control, and mitigation schemes fail to avoid or suppress RE generation, active control of the RE beam may be an important line of defense to prevent the rapid, localized deposition of RE beam energy onto vulnerable vessel sections. During and immediately after the current quench, excessive radial compression of the runaway beams is avoided by a combination of techniques, improving the likelihood of the beams surviving this dynamic period without a fast termination. Once stabilized, the runaway beams are held in a steady state (out to the ohmic flux limit) with the application of active plasma current and position controls. Beam interaction with the vessel wall is minimized by avoiding distinct thresholds for enhanced wall interaction at small and large radii, corresponding to inner wall and outer limiter interaction, respectively. Staying within the 'safe zone' between those radial thresholds allows for the sustainment of long-lived, quiescent runaway beams. The total beam energy and runaway electron population are then dissipated gradually by a controlled ramp-down of the runaway current.

  19. Control of post-disruption runaway electron beams in DIII-D

    SciTech Connect

    Eidietis, N. W.; Commaux, Nicolas JC; Hollmann, E. M.; Humphrey, D. A.; Jernigan, T. C.; Moyer, R.A.; Strait, E. J.; Van Zeeland, M. A.; Wesley, J. C.

    2012-01-01

    Recent experiments in the DIII-D tokamak have demonstrated real-time control and dissipation of post-disruption runaway electron (RE) beams. In the event that disruption avoidance, control, and mitigation schemes fail to avoid or suppress RE generation, active control of the RE beam may be an important line of defense to prevent the rapid, localized deposition of RE beam energy onto vulnerable vessel sections. During and immediately after the current quench, excessive radial compression of the runaway beams is avoided by a combination of techniques, improving the likelihood of the beams surviving this dynamic period without a fast termination. Once stabilized, the runaway beams are held in a steady state (out to the ohmic flux limit) with the application of active plasma current and position controls. Beam interaction with the vessel wall is minimized by avoiding distinct thresholds for enhanced wall interaction at small and large radii, corresponding to inner wall and outer limiter interaction, respectively. Staying within the 'safe zone' between those radial thresholds allows for the sustainment of long-lived, quiescent runaway beams. The total beam energy and runaway electron population are then dissipated gradually by a controlled ramp-down of the runaway current.

  20. Analysis of Power Converter Losses in Vector Control System of a Self-Excited Induction Generator

    NASA Astrophysics Data System (ADS)

    Bašić, Mateo; Vukadinović, Dinko; Polić, Miljenko

    2014-03-01

    This paper provides analysis of losses in the hysteresis-driven three-phase power converter with IGBTs and free-wheeling diodes. The converter under consideration is part of the self-excited induction generator (SEIG) vector control system. For the analysis, the SEIG vector control system is used in which the induction generator iron losses are taken into account. The power converter losses are determined by using a suitable loss estimation algorithm reported in literature. The chosen algorithm allows the power converter losses to be determined both by type (switching/conduction losses) and by converter component (IGBT/diode losses). The overall power converter losses are determined over wide ranges of rotor speed, dc-link voltage and load resistance, and subsequently used for offline correction of the overall control system's losses (efficiency) obtained through control system simulations with an ideal power converter. The control system's efficiency values obtained after the correction are compared with the measured values.

  1. Optimum vibration control of flexible beams by piezo-electric actuators

    NASA Technical Reports Server (NTRS)

    Baz, A.; Poh, S.; Studer, P.

    1988-01-01

    The utilization of piezoelectric actuators in controlling the structural vibrations of flexible beams is examined. A Modified Independent Modal Space Control (MIMSC) method is devised to enable the selection of the optimal location, control gains and excitation voltage of the piezoelectric actuators in a way that would minimize the amplitudes of vibrations of beams to which these actuators are bonded, as well as the input control energy necessary to suppress these vibrations. The developed method accounts for the effects that the piezoelectric actuators have on changing the elastic and inertial properties of the flexible beams. Numerical examples are presented to illustrate the application of the developed MIMSC method in minimizing the structural vibrations of beams of different materials when subjected to different loading and end conditions using ceramic or polymeric piezoelectric actuators. The obtained results emphasize the importance of the devised method in designing more realistic active control systems for flexible beams, in particular, and large flexible structures in general.

  2. Optimum vibration control of flexible beams by piezo-electric actuators

    NASA Technical Reports Server (NTRS)

    Baz, A.; Poh, S.

    1987-01-01

    The utilization of piezoelectric actuators in controlling the structural vibrations of flexible beams is examined. A Modified Independent Modal Space Control (MIMSC) method is devised to enable the selection of the optimal location, control gains and excitation voltage of the piezoelectric actuators in a way that would minimize the amplitudes of vibrations of beams to which these actuators are bonded, as well as the input control energy necessary to suppress these vibrations. The developed method accounts for the effects that the piezoelectric actuators have on changing the elastic and inertial properties of the flexible beams. Numerical examples are presented to illustrate the application of the developed MIMSC method in minimizing the structural vibrations of beams of different materials when subjected to different loading and end conditions using ceramic or polymeric piezoelectric actuators. The obtained results emphasize the importance of the devised method in designing more realistic active control systems for flexible beams, in particular, and large flexible structures in general.

  3. The Role of Loss of Control Eating in Purging Disorder

    PubMed Central

    Forney, K. Jean; Haedt-Matt, Alissa A.; Keel, Pamela K.

    2014-01-01

    Objective Purging Disorder (PD), an Other Specified Feeding or Eating Disorder,1 is characterized by recurrent purging in the absence of binge eating. Though objectively large binge episodes are not present, individuals with PD may experience a loss of control (LOC) while eating a normal or small amounts of food. The present study sought to examine the role of LOC eating in PD using archival data from 101 women with PD. Method Participants completed diagnostic interviews and self-report questionnaires. Analyses examined the relationship between LOC eating and eating disorder features, psychopathology, personality traits, and impairment, in bivariate models and then in multivariate models controlling for purging frequency, age, and body mass index. Results Across bivariate and multivariate models, LOC eating frequency was associated with greater disinhibition around food, hunger, depressive symptoms, negative urgency, and distress and impairment. Discussion LOC eating is a clinically significant feature of PD and should be considered in future definitions of PD. Future research should examine whether LOC eating better represents a dimension of severity in PD or a specifier that may impact treatment response or course. PMID:24185981

  4. Event-Driven Control for Networked Control Systems With Quantization and Markov Packet Losses.

    PubMed

    Yang, Hongjiu; Xu, Yang; Zhang, Jinhui

    2016-05-23

    In this paper, event-driven is used in a networked control system (NCS) which is subjected to the effect of quantization and packet losses. A discrete event-detector is used to monitor specific events in the NCS. Both an arbitrary region quantizer and Markov jump packet losses are also considered for the NCS. Based on zoom strategy and Lyapunov theory, a complete proof is given to guarantee mean square stability of the closed-loop system. Stabilization of the NCS is ensured by designing a feedback controller. Lastly, an inverted pendulum model is given to show the advantages and effectiveness of the proposed results.

  5. Controlling multiple filaments by relativistic optical vortex beams in plasmas.

    PubMed

    Ju, L B; Huang, T W; Xiao, K D; Wu, G Z; Yang, S L; Li, R; Yang, Y C; Long, T Y; Zhang, H; Wu, S Z; Qiao, B; Ruan, S C; Zhou, C T

    2016-09-01

    Filamentation dynamics of relativistic optical vortex beams (OVBs) propagating in underdense plasma is investigated. It is shown that OVBs with finite orbital angular momentum (OAM) exhibit much more robust propagation behavior than the standard Gaussian beam. In fact, the growth rate of the azimuthal modulational instability decreases rapidly with increase of the OVB topological charge. Thus, relativistic OVBs can maintain their profiles for significantly longer distances in an underdense plasma before filamentation occurs. It is also found that an OVB would then break up into regular filament patterns due to conservation of the OAM, in contrast to a Gaussian laser beam, which in general experiences random filamentation.

  6. Apparatus and process for active pulse intensity control of laser beam

    DOEpatents

    Wilcox, Russell B.

    1992-01-01

    An optically controlled laser pulse energy control apparatus and process is disclosed wherein variations in the energy of a portion of the laser beam are used to vary the resistance of a photodetector such as a photoresistor through which a control voltage is fed to a light intensity controlling device through which a second portion of the laser beam passes. Light attenuation means are provided to vary the intensity of the laser light used to control the resistance of the photodetector. An optical delay path is provided through which the second portion of the beam travels before reaching the light intensity controlling device. The control voltage is supplied by a variable power supply. The apparatus may be tuned to properly attenuate the laser beam passing through the intensity controlling device by adjusting the power supply, the optical delay path, or the light attenuating means.

  7. Dynamics and Control of Articulated Anisotropic Timoshenko Beams

    NASA Technical Reports Server (NTRS)

    Balakrishnan, A. V.

    1996-01-01

    The paper illustrates the use of continuum models in control design for stabilizing flexible structures. A 6-DOF anisotropic Timoshenko beam with discrete nodes where lumped masses or actuators are located provides a sufficiently rich model to be of interest for mathematical theory as well as practical application. We develop concepts and tools to help answer engineering questions without having to resort to ad hoc heuristic ("physical") arguments or faith. In this sense the paper is more mathematically oriented than engineering papers and vice versa at the same time. For instance we make precise time-domain solutions using the theory of semigroups of operators rather than formal "inverse Laplace transforms." We show that the modes arise as eigenvalues of the generator of the semigroup, which are then related to the eigenvalues of the stiffness operator. With the feedback control, the modes are no longer orthogonal and the question naturally arises as to whether there is still a modal expansion. Here we prove that the eigenfunctions yield a biorthogonal Riesz basis and indicate the corresponding expansion. We prove mathematically that the number of eigenvalues is nonfinite, based on the theory of zeros of entire functions. We make precise the notion of asymptotic modes and indicate how to calculate them. Although limited by space, we do consider the root locus problem and show for instance that the damping at first increases as the control gain increases but starts to decrease at a critical value, and goes to zero as the gain increases without bound. The undamped oscillatory modes remain oscillatory and the rigid-body modes go over into deadbeat modes. The Timoshenko model dynamics are translated into a canonical wave equation in a Hilbert space. The solution is shown to require the use of an "energy" norm which is no more than the total energy: potential plus kinetic. We show that, under an appropriate extension of the notion of controllability, rate feedback with

  8. Controlling multipolar surface plasmon excitation through the azimuthal phase structure of electron vortex beams

    NASA Astrophysics Data System (ADS)

    Ugarte, Daniel; Ducati, Caterina

    2016-05-01

    We have theoretically studied how the azimuthal phase structure of an electron vortex beam excites surface plasmons on metal particles of different geometries as observed in electron energy loss spectroscopy (EELS). We have developed a semiclassical approximation combining a ring-shaped beam and the dielectric formalism. Our results indicate that for the case of total orbital angular momentum transfer, we can manipulate surface plasmon multipole excitation and even attain an enhancement factor of several orders of magnitude. Since electron vortex beams interact with particles mostly through effects due to azimuthal symmetry, i.e., in the plane perpendicular to the electron beam, anisotropy information (longitudinal and transversal) of the sample may be derived in EELS studies by comparing nonvortex and vortex beam measurements.

  9. Topology Control in Aerial Multi Beam Directional Networks

    DTIC Science & Technology

    2017-04-24

    to each neighbor, and thus seek to have as few nodes in the same beam as possible. While high throughput is an important aspect in commu- nications...allow for a tailored approach based on the relative importance of throughput and connectivity. We simulate these two algorithms using the beam pattern...11 end V. RESULTS In order to evaluate the performance of these algorithms, each was implemented in MATLAB and then the resulting graph was imported

  10. Vibration control of pre-twisted rotating composite thin-walled beams with piezoelectric fiber composites

    NASA Astrophysics Data System (ADS)

    Choi, Seung-Chan; Park, Jae-Sang; Kim, Ji-Hwan

    2007-02-01

    Rotating composite beam structures like blades are applied in many fields of aerospace and mechanical engineering. In this research, bending vibration control of the pre-twisted rotating composite thin-walled beam is studied. The formulation is based on single cell composite beam including a warping function, centrifugal force, Coriolis acceleration, pre-twist angle and piezoelectric effect. A negative velocity feedback control algorithm is applied to realize the adaptive capability of the beam. Using a finite-element method, numerical simulations show that macro-fiber composite (MFC) actuators which are piezoelectric fiber composites and PVDF sensors can generate active vibration control effect. Relations between active vibration control effect and design parameters of beams such as rotating speeds, pre-twist angles and fiber orientations in a host structure are investigated in detail. Besides, a case study conformed that the effective damping performance can be obtained by suitable arrangement and distribution of the sensor and actuator pairs.

  11. Enhancement of beam pulse controllability for a single-pulse formation system of a cyclotron

    SciTech Connect

    Kurashima, Satoshi Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Okumura, Susumu; Taguchi, Mitsumasa; Fukuda, Mitsuhiro

    2015-07-15

    The single-pulse formation technique using a beam chopping system consisting of two types of high-voltage beam kickers was improved to enhance the quality and intensity of the single-pulse beam with a pulse interval over 1 μs at the Japan Atomic Energy Agency cyclotron facility. A contamination rate of neighboring beam bunches in the single-pulse beam was reduced to less than 0.1%. Long-term purification of the single pulse beam was guaranteed by the well-controlled magnetic field stabilization system for the cyclotron magnet. Reduction of the multi-turn extraction number for suppressing the neighboring beam bunch contamination was achieved by restriction of a beam phase width and precise optimization of a particle acceleration phase. In addition, the single-pulse beam intensity was increased by a factor of two or more by a combination of two types of beam bunchers using sinusoidal and saw-tooth voltage waveforms. Provision of the high quality intense single-pulse beam contributed to improve the accuracy of experiments for investigation of scintillation light time-profile and for neutron energy measurement by a time-of-flight method.

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

    DOE PAGES

    Swanekamp, S. B.; Richardson, A. S.; Angus, J. R.; ...

    2015-02-06

    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 (I1), while the outer conductor carries the remainder (I2). 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 (I2-I1), while the average force on the envelope (the beam width) is proportional to the beam current Ib = (I2 + I1). The values of I1more » and I2 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. As a result, 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.« less

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

    SciTech Connect

    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.

    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.

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

    SciTech Connect

    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.

    2015-02-06

    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 (I1), while the outer conductor carries the remainder (I2). 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 (I2-I1), while the average force on the envelope (the beam width) is proportional to the beam current Ib = (I2 + I1). The values of I1 and I2 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. As a result, 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.

  15. Retrograde amnesia produced by electron beam exposure: casual parameters and duration of memory loss. Final report for November 84

    SciTech Connect

    Wheeler, T.G.; Hardy, K.A.

    1985-01-01

    The production of retrograde amnesia (RA) upon electron-beam exposure was investigated. RA production was evaluated using a single-trial avoidance task for 10, 1, and 0.1 microsecond pulsed exposures. The dose-response curve obtained at each pulse duration showed significant RA production. The most effective dose range was 0.1-10 rad at a dose rate of 1,000,000 rad/sec. By employing a 10 rad (1,000,000 rad/s) pulse, a memory loss of the events occurring in the previous 4 sec was demonstrated. The conclusion was that the RA effect might be due to sensory system activation which provided a novel stimulus that masked previous stimuli.

  16. Useful technique for analysis and control of the acceleration beam phase in the azimuthally varying field cyclotron

    NASA Astrophysics Data System (ADS)

    Kurashima, Satoshi; Yuyama, Takahiro; Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Okumura, Susumu; Fukuda, Mitsuhiro

    2010-03-01

    We have developed a new technique for analysis and control of the acceleration beam phase in the cyclotron. In this technique, the beam current pattern at a fixed radius r is measured by slightly scanning the acceleration frequency in the cyclotron. The acceleration beam phase is obtained by analyzing symmetry of the current pattern. Simple procedure to control the acceleration beam phase by changing coil currents of a few trim coils was established. The beam phase width is also obtained by analyzing gradient of the decreasing part of the current pattern. We verified reliability of this technique with 260 MeV N20e7+ beams which were accelerated on different tuning condition of the cyclotron. When the acceleration beam phase was around 0°, top of the energy gain of cosine wave, and the beam phase width was about 6° in full width at half maximum, a clear turn pattern of the beam was observed with a differential beam probe in the extraction region. Beam phase widths of ion beams at acceleration harmonics of h =1 and h =2 were estimated without beam cutting by phase-defining slits. We also calculated the beam phase widths roughly from the beam current ratio between the injected beam and the accelerated beam in the cyclotron without operating the beam buncher. Both beam phase widths were almost the same for h =1, while phase compressions by a factor of about 3 were confirmed for h =2.

  17. Useful technique for analysis and control of the acceleration beam phase in the azimuthally varying field cyclotron

    SciTech Connect

    Kurashima, Satoshi; Yuyama, Takahiro; Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Okumura, Susumu; Fukuda, Mitsuhiro

    2010-03-15

    We have developed a new technique for analysis and control of the acceleration beam phase in the cyclotron. In this technique, the beam current pattern at a fixed radius r is measured by slightly scanning the acceleration frequency in the cyclotron. The acceleration beam phase is obtained by analyzing symmetry of the current pattern. Simple procedure to control the acceleration beam phase by changing coil currents of a few trim coils was established. The beam phase width is also obtained by analyzing gradient of the decreasing part of the current pattern. We verified reliability of this technique with 260 MeV {sup 20}Ne{sup 7+} beams which were accelerated on different tuning condition of the cyclotron. When the acceleration beam phase was around 0 deg., top of the energy gain of cosine wave, and the beam phase width was about 6 deg. in full width at half maximum, a clear turn pattern of the beam was observed with a differential beam probe in the extraction region. Beam phase widths of ion beams at acceleration harmonics of h=1 and h=2 were estimated without beam cutting by phase-defining slits. We also calculated the beam phase widths roughly from the beam current ratio between the injected beam and the accelerated beam in the cyclotron without operating the beam buncher. Both beam phase widths were almost the same for h=1, while phase compressions by a factor of about 3 were confirmed for h=2.

  18. Double-beam cantilever structure with embedded intelligent damping block: Dynamics and control

    NASA Astrophysics Data System (ADS)

    Szmidt, Tomasz; Pisarski, Dominik; Bajer, Czesław; Dyniewicz, Bartłomiej

    2017-08-01

    In this paper a semi-active method to control the vibrations of twin beams connected at their tips by a smart damping element is investigated. The damping element can be made of a magnetorheological elastomer or a smart material of another type, for instance vacuum packed particles. What is crucial is the ability to modify the storage and loss moduli of the damping block by means of devices attached directly to the vibrating structure. First, a simple dynamical model of the system is proposed. The continuous model is discretized using the Galerkin procedure. Then, a practical state-feedback control law is developed. The control strategy aims at achieving the best instantaneous energy dissipation of the system. Numerical simulations confirm its effectiveness in reducing free vibrations. The proposed control strategy appears to be robust in the sense that its application does not require any knowledge of the initial conditions imposed on the structure, and its performance is better than passive solutions, especially for the system induced in the first mode.

  19. Genetic Control of Weight Loss During Pneumonic Burkholderia pseudomallei Infection

    PubMed Central

    Emery, Felicia D.; Parvathareddy, Jyothi; Pandey, Ashutosh K.; Cui, Yan; Williams, Robert W.; Miller, Mark A.

    2014-01-01

    Burkholderia pseudomallei (Bp) is the causal agent of a high morbidity/mortality disease syndrome known as melioidosis. This syndrome can range from acute fulminate disease to chronic, local, and disseminated infections that are often difficult to treat because Bp exhibits resistance to many antibiotics. Bp is a prime candidate for use in biological warfare/terrorism and is classified as a Tier-1 Select Agent by HHS and APHIS. It is known that inbred mouse strains display a range of susceptibility to Bp and that the murine infection model is ideal for studying acute melioidosis. Here we exploit a powerful mouse genetics resource that consists of a large family of BXD type recombinant inbred strains, to perform genome-wide linkage analysis of the weight loss phenotype following pneumonic infection with Bp. We infected parental mice and 32 BXD strains with 50-100 CFU of Bp (strain 1026b) and monitored weight retention each day over an eleven-day time course. Using the computational tools in GeneNetwork, we performed genome-wide linkage analysis to identify an interval on chromosome 12 that appears to control the weight retention trait. We then analysed and ranked positional candidate genes in this interval, several of which have intriguing connections with innate immunity, calcium homeostasis, lipid transport, host cell growth and development, and autophagy. PMID:24687986

  20. E-beam-patterned hydrogels to control nanoscale surface bioactivity

    NASA Astrophysics Data System (ADS)

    Krsko, P.; Saaem, I.; Clancy, R.; Geller, H.; Soteropoulos, P.; Libera, M.

    2005-11-01

    We are interested in controlling the spatial distribution of proteins on surfaces at cellular and subcellular length scales. To do this, we use a variation of e-beam lithography in a field-emission scanning electron microscope (SEM) to radiation crosslink thin films of water- soluble polymers such as poly(ethylene glycol) [PEG] and poly (carboxylic acids). We can simultaneously pattern the resulting hydrogels on silicon or glass surfaces with nanoscale and microscale feature sizes. Using hydroxy-terminated PEG 6800 we create gels with swell ratios between unity and fifteen depending on the degree of radiation crosslinking, and the swelling properties can be interpreted in terms of the Flory-Rehner formulation modified for one-dimensional swelling. While lightly-crosslinked PEG gels resist protein adsorption and cell adhesion as expected, highly crosslinked PEG gels adsorb such proteins as fibronectin and laminin and consequently become adhesive to fibroblasts, macrophages, and neurons. By spatially modulating the degree of crosslinking, we can localize these cells on surfaces and, for example, direct neurite outgrowth. If instead of using hydroxy-terminated PEG we use amine- terminated PEG, we introduce the additional flexibility of creating high-swelling PEG gels that resist nonspecific protein adsorption but to which specific proteins can be covalently bound. These can be surface patterned at submicron spacings, and we can pattern 7500 nanohydrogels in a 100 micron diameter arrays in 10 seconds. This is an areal density ~104 times greater than a modern DNA/protein chip, and the required bioreagents for chip fabrication and processing are proportionately less. We can bind fibronectin and laminin to different arrays, and we show that these proteins maintain their biospecificity after binding to the nanohydrogels with high fidelity. Looking to applications in next-generation protein-chip technology, our most recent experiments compare the performance of nanohydrogel

  1. Examination of Icing Induced Loss of Control and Its Mitigations

    NASA Technical Reports Server (NTRS)

    Reehorst, Andrew L.; Addy, Harold E., Jr.; Colantonio, Renato O.

    2010-01-01

    Factors external to the aircraft are often a significant causal factor in loss of control (LOC) accidents. In today s aviation world, very few accidents stem from a single cause and typically have a number of causal factors that culminate in a LOC accident. Very often the "trigger" that initiates an accident sequence is an external environment factor. In a recent NASA statistical analysis of LOC accidents, aircraft icing was shown to be the most common external environmental LOC causal factor for scheduled operations. When investigating LOC accident or incidents aircraft icing causal factors can be categorized into groups of 1) in-flight encounter with super-cooled liquid water clouds, 2) take-off with ice contamination, or 3) in-flight encounter with high concentrations of ice crystals. As with other flight hazards, icing induced LOC accidents can be prevented through avoidance, detection, and recovery mitigations. For icing hazards, avoidance can take the form of avoiding flight into icing conditions or avoiding the hazard of icing by making the aircraft tolerant to icing conditions. Icing detection mitigations can take the form of detecting icing conditions or detecting early performance degradation caused by icing. Recovery from icing induced LOC requires flight crew or automated systems capable of accounting for reduced aircraft performance and degraded control authority during the recovery maneuvers. In this report we review the icing induced LOC accident mitigations defined in a recent LOC study and for each mitigation describe a research topic required to enable or strengthen the mitigation. Many of these research topics are already included in ongoing or planned NASA icing research activities or are being addressed by members of the icing research community. These research activities are described and the status of the ongoing or planned research to address the technology needs is discussed

  2. CRionScan: A stand-alone real time controller designed to perform ion beam imaging, dose controlled irradiation and proton beam writing

    NASA Astrophysics Data System (ADS)

    Daudin, L.; Barberet, Ph.; Serani, L.; Moretto, Ph.

    2013-07-01

    High resolution ion microbeams, usually used to perform elemental mapping, low dose targeted irradiation or ion beam lithography needs a very flexible beam control system. For this purpose, we have developed a dedicated system (called “CRionScan”), on the AIFIRA facility (Applications Interdisciplinaires des Faisceaux d'Ions en Région Aquitaine). It consists of a stand-alone real-time scanning and imaging instrument based on a Compact Reconfigurable Input/Output (Compact RIO) device from National Instruments™. It is based on a real-time controller, a Field Programmable Gate Array (FPGA), input/output modules and Ethernet connectivity. We have implemented a fast and deterministic beam scanning system interfaced with our commercial data acquisition system without any hardware development. CRionScan is built under LabVIEW™ and has been used on AIFIRA's nanobeam line since 2009 (Barberet et al., 2009, 2011) [1,2]. A Graphical User Interface (GUI) embedded in the Compact RIO as a web page is used to control the scanning parameters. In addition, a fast electrostatic beam blanking trigger has been included in the FPGA and high speed counters (15 MHz) have been implemented to perform dose controlled irradiation and on-line images on the GUI. Analog to Digital converters are used for the beam current measurement and in the near future for secondary electrons imaging. Other functionalities have been integrated in this controller like LED lighting using Pulse Width Modulation and a “NIM Wilkinson ADC” data acquisition.

  3. Beam-Beam Interactions

    SciTech Connect

    Sramek, Christopher

    2003-09-05

    At the interaction point of a particle accelerator, various phenomena occur which are known as beam-beam effects. Incident bunches of electrons (or positrons) experience strong electromagnetic fields from the opposing bunches, which leads to electron deflection, beamstrahlung and the creation of electron/positron pairs and hadrons due to two-photon exchange. In addition, the beams experience a ''pinch effect'' which focuses each beam and results in either a reduction or expansion of their vertical size. Finally, if a beam's disruption parameter is too large, the beam can develop a sinusoidal distortion, or two-stream (kink) instability. This project simulated and studied these effects as they relate to luminosity, deflection angles and energy loss in order to optimize beam parameters for the Next Linear Collider (NLC). Using the simulation program Guinea-Pig, luminosity, deflection angle and beam energy data was acquired for different levels of beam offset and distortion. Standard deflection curves and luminosity plots agreed with theoretical models but also made clear the difficulties of e-e- feedback. Simulations emphasizing kink instability in modulated and straight beam collisions followed qualitative behavioral predictions and roughly fit recent analytic calculations. Finally, a study of e-e- collisions under design constraints for the NLC provided new estimates of how luminosity, beamstrahlung energy loss, upsilon parameter and deflection curve width scale with beam spotsizes.

  4. 40 CFR 1060.104 - What running loss emission control requirements apply?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 33 2014-07-01 2014-07-01 false What running loss emission control... STATIONARY EQUIPMENT Emission Standards and Related Requirements § 1060.104 What running loss emission control requirements apply? (a) Engines and equipment must meet running loss requirements as follows:...

  5. 40 CFR 1060.104 - What running loss emission control requirements apply?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 34 2013-07-01 2013-07-01 false What running loss emission control... STATIONARY EQUIPMENT Emission Standards and Related Requirements § 1060.104 What running loss emission control requirements apply? (a) Engines and equipment must meet running loss requirements as follows:...

  6. Procedures control total mud losses while drilling in deep water

    SciTech Connect

    Dewar, J. ); Halkett, D. )

    1993-11-01

    In the deepwater (830-1,000 m) drilling program offshore Philippines, reefal limestones were encountered in which total mud losses could be expected because of the presence of large fractures. The danger was that a sudden drop in hydrostatic head (resulting from the losses) could allow any natural gas to enter the well bore quickly. The gas could then migrate up the well bore and form hydrates in the blowout preventers (BOPs). Once hydrates form, they are difficult to remove and can make a BOP stack inoperable. To combat this potential problem, containment procedures were developed to cope with these fluid losses. The philosophy behind the procedures was to prevent hydrocarbons from entering the well bore and, if they did enter, to ensure that they did not move up the well bore and into the riser. Additionally, procedures were developed to allow drilling to continue during the losses and the curing of losses.

  7. Modeling and control of copper loss in smelting slag

    NASA Astrophysics Data System (ADS)

    Tan, Pengfu

    2011-12-01

    A series of technical improvements have been implemented to address the issue of high copper losses in rotary holding furnace (RHF) slag, which were experienced at the Xstrata Copper Smelter at Mount Isa in 2007 and 2008. The copper losses in smelting slag in the RHF were more than 3% in 2006 and 2007. Thermodynamic models and viscosity models have been applied in the operation of Xstrata Copper Smelter in Australia. The theory of RHF key performance indicators has also been developed to reduce the copper losses in RHF slag. The RHF KPIs Theory has been applied in Mount Isa Copper Smelter. The copper losses in RHF slag dropped from 3.1% in 2007 to 0.76% in April 2009. The average copper loss in RHF slag in 2009 and 2010 was about 0.9%.

  8. Boundary control of a Timoshenko beam system with input dead-zone

    NASA Astrophysics Data System (ADS)

    He, Wei; Meng, Tingting; Liu, Jin-Kun; Qin, Hui

    2015-06-01

    In this paper, boundary control is designed for a Timoshenko beam system with the input dead-zone. By the Hamilton's principle, the dynamics of the Timoshenko beam system is represented by a distributed parameter model with two partial differential equations and four ordinary differential equations. The bounded part is separated from the input dead-zone and then forms the disturbance-like term together with the boundary disturbance, which finally acts on the Timoshenko beam system. Boundary control, based on the Lyapunov's direct method, is proposed to ensure the Timoshenko beam converge into a small neighbourhood of zero, where stability of the system is also analysed. Besides, the existence and uniqueness of the solution of the Timoshenko beam system are proved. Simulations are provided to reveal the applicability and effectiveness of the proposed control scheme.

  9. Optimal vibration control of beams with total and partial MR-fluid treatments

    NASA Astrophysics Data System (ADS)

    Rajamohan, Vasudevan; Sedaghati, Ramin; Rakheja, Subhash

    2011-11-01

    This paper presents the synthesis of full state and limited state flexible mode shape (FMS) based controllers for the suppression of transient and forced vibration of a cantilever beam with full and partial magnetorheological (MR) fluid treatments. The governing equations of motion of the three layer MR sandwich beam are expressed in the state variable form comprising a function of the control magnetic field. An optimal control strategy based on the linear quadratic regulator (LQR) and a full state dynamic observer is formulated to suppress the vibration of the beam under limited magnetic field intensity. The lower flexural mode shapes of the passive beam are used to obtain estimates of the deflection states so as to formulate a limited state LQR control synthesis. The transient and forced vibration control performances of both the full state observer-based and the limited state FMS-based LQR control strategies are evaluated for the fully as well as partially treated MR-fluid sandwich beams. The results show that the full state observer-based LQR control can substantially reduce the tip deflection responses and the settling time of free vibration oscillations. The limited state LQR control based on the mode shapes effectively adapts to the deflections of the closed loop beam and thus yields vibration attenuation performance comparable to that of the full state LQR controller. The partially treated beam with MR-fluid concentration near the free end also yields vibration responses comparable to the fully treated beam, while the natural frequencies of the partially treated beams are considerably higher.

  10. Active control of the forced and transient response of a finite beam. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Post, John T.

    1990-01-01

    Structural vibrations from a point force are modelled on a finite beam. This research explores the theoretical limit on controlling beam vibrations utilizing another point source as an active controller. Three different types of excitation are considered, harmonic, random, and transient. For harmonic excitation, control over the entire beam length is possible only when the excitation frequency is near a resonant frequency of the beam. Control over a subregion may be obtained even between resonant frequencies at the cost of increasing the vibration outside of the control region. For random excitation, integrating the expected value of the displacement squared over the required interval, is shown to yield the identical cost function as obtained by integrating the cost function for harmonic excitation over all excitation frequencies. As a result, it is always possible to reduce the cost function for random excitation whether controlling the entire beam or just a subregion, without ever increasing the vibration outside the region in which control is desired. The last type of excitation considered is a single, transient pulse. The form of the controller is specified as either one or two delayed pulses, thus constraining the controller to be casual. The best possible control is examined while varying the region of control and the controller location. It is found that control is always possible using either one or two control pulses.

  11. Methodological demonstration of laser beam pointing control for space gravitational wave detection missions

    SciTech Connect

    Dong, Yu-Hui; Liu, He-Shan; Luo, Zi-Ren; Li, Yu-Qiong; Jin, Gang

    2014-07-15

    In space laser interferometer gravitational wave (G.W.) detection missions, the stability of the laser beam pointing direction has to be kept at 10 nrad/√Hz. Otherwise, the beam pointing jitter noise will dominate the noise budget and make the detection of G.W. impossible. Disturbed by the residue non-conservative forces, the fluctuation of the laser beam pointing direction could be a few μrad/√Hz at frequencies from 0.1 mHz to 10 Hz. Therefore, the laser beam pointing control system is an essential requirement for those space G.W. detection missions. An on-ground test of such beam pointing control system is performed, where the Differential Wave-front Sensing technique is used to sense the beams pointing jitter. An active controlled steering mirror is employed to adjust the beam pointing direction to compensate the jitter. The experimental result shows that the pointing control system can be used for very large dynamic range up to 5 μrad. At the interested frequencies of space G.W. detection missions, between 1 mHz and 1 Hz, beam pointing stability of 6 nrad/√Hz is achieved.

  12. Controlling FAMA by the Ptolemy II model of ion beam transport

    NASA Astrophysics Data System (ADS)

    Balvanović, R.; Rađenović, B.; Beličev, P.; Nešković, N.

    2009-08-01

    FAMA is a facility for modification and analysis of materials with ion beams. Due to the wide range of ion beams and energies used in the facility and its future expansion, the need has arisen for faster tuning of ion beams transport control parameters. With this aim, a new approach to modeling ion-beam transport system was developed, based on the Ptolemy II modeling and design framework. A model in Ptolemy II is a hierarchical aggregation of components called actors, which communicate with other actors using tokens, or pieces of data. Each ion optical element is modeled by a composite actor implementing beam matrix transformation function, while tokens carry beam matrix data. A basic library of models of typical ion optical elements is developed, and a complex model of FAMA ion beam transport system is hierarchically integrated with bottom-up approach. The model is extended to include control functions. The developed model is modular, flexible and extensible. The results obtained by simulation on the model demonstrate easy and efficient tuning of beam line control parameters. Fine tuning of control parameters, due to uncertainties inherent to modeling, still has to be performed on-line.

  13. Beam control and multi-color routing with spatial photonic defect modes.

    PubMed

    Wang, Xiaosheng; Chen, Zhigang

    2009-09-14

    We demonstrate tunable re-directing, blocking, and splitting of a light beam along defect channels based on spatial bandgap guidance in two-dimensional photonic lattices. We show the possibility for linear control of beam propagation and multicolor routing with specially designed junctions and surface structures embedded in otherwise uniform square lattices.

  14. Methodological demonstration of laser beam pointing control for space gravitational wave detection missions.

    PubMed

    Dong, Yu-Hui; Liu, He-Shan; Luo, Zi-Ren; Li, Yu-Qiong; Jin, Gang

    2014-07-01

    In space laser interferometer gravitational wave (G.W.) detection missions, the stability of the laser beam pointing direction has to be kept at 10 nrad/√Hz. Otherwise, the beam pointing jitter noise will dominate the noise budget and make the detection of G.W. impossible. Disturbed by the residue non-conservative forces, the fluctuation of the laser beam pointing direction could be a few μrad/√Hz at frequencies from 0.1 mHz to 10 Hz. Therefore, the laser beam pointing control system is an essential requirement for those space G.W. detection missions. An on-ground test of such beam pointing control system is performed, where the Differential Wave-front Sensing technique is used to sense the beams pointing jitter. An active controlled steering mirror is employed to adjust the beam pointing direction to compensate the jitter. The experimental result shows that the pointing control system can be used for very large dynamic range up to 5 μrad. At the interested frequencies of space G.W. detection missions, between 1 mHz and 1 Hz, beam pointing stability of 6 nrad/√Hz is achieved.

  15. Combined effects of nuclear and electronic energy losses in solids irradiated with a dual-ion beam

    SciTech Connect

    Thome, Lionel; Debelle, Aurelien; Garrido, Frederico; Trocellier, Patrick; Serruys, Yves; Miro, Sandrine

    2013-04-08

    Single and dual-beam irradiations of oxide (c-ZrO{sub 2}, MgO, Gd{sub 2}Ti{sub 2}O{sub 7}) and carbide (SiC) single crystals were performed to study combined effects of nuclear (S{sub n}) and electronic (S{sub e}) energy losses. Rutherford backscattering experiments in channeling conditions show that the S{sub n}/S{sub e} cooperation induces a strong decrease of the irradiation-induced damage in SiC and MgO and almost no effects in c-ZrO{sub 2} and Gd{sub 2}Ti{sub 2}O{sub 7}. The healing process is ascribed to electronic excitations arising from the electronic energy loss of swift ions. These results present a strong interest for both fundamental understanding of the ion-solid interactions and technological applications in the nuclear industry where expected cooperative S{sub n}/S{sub e} effects may lead to the preservation of the integrity of nuclear devices.

  16. Evaluation of diagnostic accuracy of conventional and digital periapical radiography, panoramic radiography, and cone-beam computed tomography in the assessment of alveolar bone loss.

    PubMed

    Takeshita, Wilton Mitsunari; Vessoni Iwaki, Lilian Cristina; Da Silva, Mariliani Chicarelli; Tonin, Renata Hernandes

    2014-07-01

    To evaluate the diagnostic accuracy of different radiographic methods in the assessment of proximal alveolar bone loss (ABL). ABL, the distance between cement-enamel junction and alveolar bone crest, was measured in 70 mandibular human teeth - directly on the mandibles (control), using conventional periapical radiography with film holders (Rinn XCP and Han-Shin), digital periapical radiography with complementary metal-oxide semiconductor sensor, conventional panoramic, and cone-beam computed tomography (CBCT). Three programs were used to measure ABL on the images: Image tool 3.0 (University of Texas Health Sciences Center, San Antonio, Texas, USA), Kodak Imaging 6.1 (Kodak Dental Imaging 6.1, Carestream Health(®), Rochester, NY, USA), and i-CAT vision 1.6.20. Statistical analysis used ANOVA and Tukey's test at 5% significance level. The tomographic images showed the highest means, whereas the lowest were found for periapical with Han-Shin. Controls differed from periapical with Han-Shin (P < 0.0001). CBCT differed from panoramic (P = 0.0130), periapical with Rinn XCP (P = 0.0066), periapical with Han-Shin (P < 0.0001), and digital periapical (P = 0.0027). Conventional periapicals with film holders differed from each other (P = 0.0007). Digital periapical differed from conventional periapical with Han-Shin (P = 0.0004). Conventional periapical with Han-Shin film holder was the only method that differed from the controls. CBCT had the closest means to the controls.

  17. Systems for controlling the intensity variations in a laser beam and for frequency conversion thereof

    DOEpatents

    Skupsky, Stanley; Craxton, R. Stephen; Soures, John

    1990-01-01

    In order to control the intensity of a laser beam so that its intensity varies uniformly and provides uniform illumination of a target, such as a laser fusion target, a broad bandwidth laser pulse is spectrally dispersed spatially so that the frequency components thereof are spread apart. A disperser (grating) provides an output beam which varies spatially in wavelength in at least one direction transverse to the direction of propagation of the beam. Temporal spread (time delay) across the beam is corrected by using a phase delay device (a time delay compensation echelon). The dispersed beam may be amplified with laser amplifiers and frequency converted (doubled, tripled or quadrupled in frequency) with nonlinear optical elements (birefringent crystals). The spectral variation across the beam is compensated by varying the angle of incidence on one of the crystals with respect to the crystal optical axis utilizing a lens which diverges the beam. Another lens after the frequency converter may be used to recollimate the beam. The frequency converted beam is recombined so that portions of different frequency interfere and, unlike interference between waves of the same wavelength, there results an intensity pattern with rapid temoral oscillations which average out rapidly in time thereby producing uniform illumination on target. A distributed phase plate (also known as a random phase mask), through which the spectrally dispersed beam is passed and then focused on a target, is used to provide the interference pattern which becomes nearly modulation free and uniform in intensity in the direction of the spectral variation.

  18. Systems for controlling the intensity variations in a laser beam and for frequency conversion thereof

    DOEpatents

    Skupsky, S.; Craxton, R.S.; Soures, J.

    1990-10-02

    In order to control the intensity of a laser beam so that its intensity varies uniformly and provides uniform illumination of a target, such as a laser fusion target, a broad bandwidth laser pulse is spectrally dispersed spatially so that the frequency components thereof are spread apart. A disperser (grating) provides an output beam which varies spatially in wavelength in at least one direction transverse to the direction of propagation of the beam. Temporal spread (time delay) across the beam is corrected by using a phase delay device (a time delay compensation echelon). The dispersed beam may be amplified with laser amplifiers and frequency converted (doubled, tripled or quadrupled in frequency) with nonlinear optical elements (birefringent crystals). The spectral variation across the beam is compensated by varying the angle of incidence on one of the crystals with respect to the crystal optical axis utilizing a lens which diverges the beam. Another lens after the frequency converter may be used to recollimate the beam. The frequency converted beam is recombined so that portions of different frequency interfere and, unlike interference between waves of the same wavelength, there results an intensity pattern with rapid temporal oscillations which average out rapidly in time thereby producing uniform illumination on target. A distributed phase plate (also known as a random phase mask), through which the spectrally dispersed beam is passed and then focused on a target, is used to provide the interference pattern which becomes nearly modulation free and uniform in intensity in the direction of the spectral variation. 16 figs.

  19. Analysis and control of the photon beam position at PLS-II

    PubMed Central

    Ko, J.; Kim, I.-Y.; Kim, C.; Kim, D.-T.; Huang, J.-Y.; Shin, S.

    2016-01-01

    At third-generation light sources, the photon beam position stability is a critical issue for user experiments. In general, photon beam position monitors are developed to detect the real photon beam position, and the position is controlled by a feedback system in order to maintain the reference photon beam position. At Pohang Light Source II, a photon beam position stability of less than 1 µm r.m.s. was achieved for a user service period in the beamline, where the photon beam position monitor is installed. Nevertheless, a detailed analysis of the photon beam position data was necessary in order to ensure the performance of the photon beam position monitor, since it can suffer from various unknown types of noise, such as background contamination due to upstream or downstream dipole radiation, and undulator gap dependence. This paper reports the results of a start-to-end study of the photon beam position stability and a singular value decomposition analysis to confirm the reliability of the photon beam position data. PMID:26917132

  20. Active Control of the Forced and Transient Response of a Finite Beam. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Post, John Theodore

    1989-01-01

    When studying structural vibrations resulting from a concentrated source, many structures may be modelled as a finite beam excited by a point source. The theoretical limit on cancelling the resulting beam vibrations by utilizing another point source as an active controller is explored. Three different types of excitation are considered, harmonic, random, and transient. In each case, a cost function is defined and minimized for numerous parameter variations. For the case of harmonic excitation, the cost function is obtained by integrating the mean squared displacement over a region of the beam in which control is desired. A controller is then found to minimize this cost function in the control interval. The control interval and controller location are continuously varied for several frequencies of excitation. The results show that control over the entire beam length is possible only when the excitation frequency is near a resonant frequency of the beam, but control over a subregion may be obtained even between resonant frequencies at the cost of increasing the vibration outside of the control region. For random excitation, the cost function is realized by integrating the expected value of the displacement squared over the interval of the beam in which control is desired. This is shown to yield the identical cost function as obtained by integrating the cost function for harmonic excitation over all excitation frequencies. As a result, it is always possible to reduce the cost function for random excitation whether controlling the entire beam or just a subregion, without ever increasing the vibration outside the region in which control is desired. The last type of excitation considered is a single, transient pulse. A cost function representative of the beam vibration is obtained by integrating the transient displacement squared over a region of the beam and over all time. The form of the controller is chosen a priori as either one or two delayed pulses. Delays

  1. Active buckling control of beams using piezoelectric actuators and strain gauge sensors

    NASA Astrophysics Data System (ADS)

    Wang, Q. S.

    2010-06-01

    In this paper, a finite element model incorporating active control techniques has been developed to stabilize the first two buckling modes of both a simply supported and a cantilevered beam. The goal is to increase the corresponding beam buckling loads by using piezoelectric actuators along with optimal feedback control. The uniform beams are bonded with two pairs of segmented piezoelectric actuators at the top and bottom. Resistive strain gauges are attached to the centres of the actuators as sensors. Measurements are taken using these, to estimate the system states. The beams are simply supported or cantilevered and subjected to a slowly increasing axial compressive load. Finite element formulations based on the classical Euler-Bernoulli beam theory and linear piezoelectric constitutive equations for the actuators are presented. The associated reduced-order modal equations and the state-space equations are derived for the design of a standard linear quadratic regulator (LQR). The finite element analysis and the active control simulation results are consistent with both theoretical analysis results and experimental data. The designed full state feedback LQR controller is shown to be successful in stabilizing the first two buckling modes of the beams. Also the control simulation shows that the present optimally located segmented actuator pairs along the beam are more effective for buckling control.

  2. The potential of electron beam radiation for simultaneous surface modification and bioresorption control of PLLA.

    PubMed

    Cairns, Marie-Louise; Dickson, Glenn R; Orr, John F; Farrar, David; Hardacre, Christopher; Sa, Jacinto; Lemoine, Patrick; Mughal, Muhammad Zeeshan; Buchanan, Fraser J

    2012-09-01

    Bioresorbable polymers have been widely investigated as materials exhibiting significant potential for successful application in the fields of tissue engineering and drug delivery. Further to the ability to control degradation, surface engineering of polymers has been highlighted as a key method central to their development. Previous work has demonstrated the ability of electron beam (e-beam) technology to control the degradation profiles and bioresorption of a number of commercially relevant bioresorbable polymers (poly-l-lactic acid (PLLA), L-lactide/DL-lactide co-polymer (PLDL) and poly(lactic-co-glycolic acid (PLGA)). This work investigates the further potential of e-beam technology to impart added biofunctionality through the manipulation of polymer (PLLA) surface properties. PLLA samples were subjected to e-beam treatments in air, with varying beam energies and doses. Surface characterization was then performed using contact angle analysis, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and atomic force microscopy. Results demonstrated a significant increase in surface wettability post e-beam treatment. In correlation with this, XPS data showed the introduction of oxygen-containing functional groups to the surface of PLLA. Raman spectroscopy indicated chain scission in the near surface region of PLLA (as predicted). However, e-beam effects on surface properties were not shown to be dependent on beam energy or dose. E-beam irradiation did not seem to affect the surface roughness of PLLA as a direct consequence of the treatment.

  3. Chemical precipitation for controlling nitrogen loss during composting.

    PubMed

    Ren, Li-Mei; Li, Guo-Xue; Shen, Yun-Jun; Schuchardt, Frank; Lu Peng

    2010-05-01

    Aimed at controlling the nitrogen loss during composting, the mixture of magnesium hydroxide (Mg(OH)( 2)) and phosphoric acid (H(3)PO(4)) (molar ratio 1:2) were utilized as additives to avoid increasing total salinity. In trial TA, the additives were put into absorption bottles connecting with a gas outlet of fermentor (ex situ method); in trial TB, the additives were directly added to the composting materials (in situ method). During the 26 day composting period, the temperature, pH, total organic carbon (TOC), total nitrogen (TN), ammonium nitrogen (NH(4)(+)-N), total phosphorus (TP), available phosphorus (AP) and germination index (GI) were measured. The experimental results show that the additives reduced the pH, while NH( 4)(+)-N and TN were obviously improved. NH(4)( +)-N was 11.9 g kg(-1) and 3 g kg(- 1) in amended compost trial (TB) and unamended compost trial (TA), respectively; TN increased from 26.5 g kg(-1) to 40.3 g kg(-1) in TB and increased from 26.5 g kg( -1) to 26.8 g kg(-1) in TA. Analysis of the TOC and carbon mass revealed that absorbents accelerated the degradation of organic matter. The germination index test showed the maturity of TB (102%) was better than TA (82%) in final compost. Furthermore, TP and AP were also obviously improved. X-ray diffraction analysis of precipitation showed that the precipitation in absorption bottle of TA was newberyite (MgHPO( 4) 3H(2)O), however, the crystal in the TB compost was struvite (MgNH(4)PO(4) 6H(2)O: magnesium ammonium phosphate). These results indicated that Mg(OH)(2) and H(3)PO( 4) could reduce the ammonia emission by struvite crystallization reaction. Optimal conditions for struvite precipitation should be determined for different systems.

  4. Controlling Mitochondrial Dynamics to Mitigate Noise-Induced Hearing Loss

    DTIC Science & Technology

    2016-10-01

    of excessive ROS by mitochondria in many different tissues of the inner ear is well recognized. Mitochondrial dysfunction, including the...of reactive oxygen species. 2. KEYWORDS Hearing loss, loud sound, mitochondria , reactive oxygen species, dynamin-related protein-1... mitochondria is an underlying mechanism of noise-induced damage to tissues in the inner ear that leads to noise-induced loss of hearing sensitivity. Our

  5. Phase control and beam steering of semiconductor laser arrays

    NASA Technical Reports Server (NTRS)

    Katz, J.

    1982-01-01

    The operational principles and a possible device configuration of one dimensional monolithically integrated semiconductor laser arrays are described. The output beam of the array can be electronically steered. Devices of the type can find applications in optical communication systems where the power levels needed are above the capability of a single laser device.

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

    SciTech Connect

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

    2015-11-18

    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 [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. For a fixed central post, the beam trajectory is controlled by varying the outer conductor radius which changes the inductance in the return-current path. The simulations show that the beam emittance is approximately constant as the beam propagates through the current divider to the target. As a result, independent control over both the current density and the beam angle at the target is possible by choosing the appropriate return-current geometry.

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

    DOE PAGES

    Swanekamp, S. B.; Angus, J. R.; Cooperstein, G.; ...

    2015-11-18

    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 [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 forcemore » on the beam trajectory is proportional to (I2-I1) and the force on the beam envelope is proportional to Ib. For a fixed central post, the beam trajectory is controlled by varying the outer conductor radius which changes the inductance in the return-current path. The simulations show that the beam emittance is approximately constant as the beam propagates through the current divider to the target. As a result, independent control over both the current density and the beam angle at the target is possible by choosing the appropriate return-current geometry.« less

  8. Dynamical beam manipulation based on 2-bit digitally-controlled coding metasurface

    NASA Astrophysics Data System (ADS)

    Huang, Cheng; Sun, Bo; Pan, Wenbo; Cui, Jianhua; Wu, Xiaoyu; Luo, Xiangang

    2017-02-01

    Recently, a concept of digital metamaterials has been proposed to manipulate field distribution through proper spatial mixtures of digital metamaterial bits. Here, we present a design of 2-bit digitally-controlled coding metasurface that can effectively modulate the scattered electromagnetic wave and realize different far-field beams. Each meta-atom of this metasurface integrates two pin diodes, and by tuning their operating states, the metasurface has four phase responses of 0, π/2, π, and 3π/2, corresponding to four basic digital elements “00”, “01”, “10”, and “11”, respectively. By designing the coding sequence of the above digital element array, the reflected beam can be arbitrarily controlled. The proposed 2-bit digital metasurface has been demonstrated to possess capability of achieving beam deflection, multi-beam and beam diffusion, and the dynamical switching of these different scattering patterns is completed by a programmable electric source.

  9. Dynamical beam manipulation based on 2-bit digitally-controlled coding metasurface.

    PubMed

    Huang, Cheng; Sun, Bo; Pan, Wenbo; Cui, Jianhua; Wu, Xiaoyu; Luo, Xiangang

    2017-02-08

    Recently, a concept of digital metamaterials has been proposed to manipulate field distribution through proper spatial mixtures of digital metamaterial bits. Here, we present a design of 2-bit digitally-controlled coding metasurface that can effectively modulate the scattered electromagnetic wave and realize different far-field beams. Each meta-atom of this metasurface integrates two pin diodes, and by tuning their operating states, the metasurface has four phase responses of 0, π/2, π, and 3π/2, corresponding to four basic digital elements "00", "01", "10", and "11", respectively. By designing the coding sequence of the above digital element array, the reflected beam can be arbitrarily controlled. The proposed 2-bit digital metasurface has been demonstrated to possess capability of achieving beam deflection, multi-beam and beam diffusion, and the dynamical switching of these different scattering patterns is completed by a programmable electric source.

  10. Dynamical beam manipulation based on 2-bit digitally-controlled coding metasurface

    PubMed Central

    Huang, Cheng; Sun, Bo; Pan, Wenbo; Cui, Jianhua; Wu, Xiaoyu; Luo, Xiangang

    2017-01-01

    Recently, a concept of digital metamaterials has been proposed to manipulate field distribution through proper spatial mixtures of digital metamaterial bits. Here, we present a design of 2-bit digitally-controlled coding metasurface that can effectively modulate the scattered electromagnetic wave and realize different far-field beams. Each meta-atom of this metasurface integrates two pin diodes, and by tuning their operating states, the metasurface has four phase responses of 0, π/2, π, and 3π/2, corresponding to four basic digital elements “00”, “01”, “10”, and “11”, respectively. By designing the coding sequence of the above digital element array, the reflected beam can be arbitrarily controlled. The proposed 2-bit digital metasurface has been demonstrated to possess capability of achieving beam deflection, multi-beam and beam diffusion, and the dynamical switching of these different scattering patterns is completed by a programmable electric source. PMID:28176870

  11. Enhanced insulin sensitivity in successful, long-term weight loss maintainers compared with matched controls with no weight loss history

    PubMed Central

    Clamp, L D; Hume, D J; Lambert, E V; Kroff, J

    2017-01-01

    Background: Weight gain is associated with deterioration in metabolic health, whereas weight loss improves insulin sensitivity. This study assesses the impact of long-term, successfully maintained weight loss and weight-loss relapse on measures of insulin sensitivity and identifies factors that explain variability in insulin sensitivity. Methods: Women (20–45 years) were recruited into four groups: reduced-overweight/obese (RED, n=15); body mass index (BMI)-matched controls (stable low-weight, n=19), BMI⩽27 kg m−2; relapsed-overweight/obese subjects (REL, n=11); and BMI-matched controls (obese stable weight, n=11), BMI⩾27 kg m−2. A 75 g oral glucose tolerance test determined fasting and 2 h plasma glucose and insulin. Homeostatic Model Assessment (HOMA-IR) and insulin sensitivity index (ISI(0,120)) assessed insulin sensitivity. Anthropometric measurements, fasting resting metabolic rate (RMR) and respiratory quotient (RQ) were measured. Questionnaires and dietary intake were recorded, and physical activity was measured using accelerometers. Results: RED were more insulin sensitive, characterised by lower fasting (P=0.001) and 2 h insulin (P=0.003) levels compared with all other groups. There were no significant differences in dietary intake, sedentary, light and moderate activity, RMR or RQ in the RED compared with the other three groups. % Body weight (BW) lost (P<0.001), % BW regained (P<0.05), body fat %, light activity (P<0.05, only log HOMA), vigorous activity (P<0.05) and RQ (P<0.01) predicted 61.4% and 59.7% of variability in log HOMA and log ISI(0,120), respectively, in multiple linear regression models. Conclusion: This study showed sustained enhanced insulin sensitivity in successful weight loss maintainers compared with BMI-matched controls with no weight loss history. Weight-loss-relapsed individuals were indistinguishable from controls. Weight loss itself was the strongest predictor of improved insulin sensitivity, whereas

  12. Beam Control and Steering in the University of Maryland Electron Ring (UMER)

    NASA Astrophysics Data System (ADS)

    Walter, M.; Bai, G.; Bernal, S.; Feldman, D.; Godlove, T.; Haber, I.; Holloway, M.; Kishek, R.; O'Shea, P.; Papadopoulos, C.; Quinn, B.; Reiser, M.; Stratakis, D.; Sutter, D.; Thangaraj, J.; Wilson, M.; Wu, C.

    2006-11-01

    The University of Maryland Electron Ring (UMER) is a low energy, high current recirculator for beam physics research. Ring construction has been completed for multi-turn operation of beams over a broad range of intensities and initial conditions. The electron beam current is adjustable up to 100 mA and pulse length as long as 100 ns. UMER is addressing issues in beam physics relevant to many applications that require intense beams of high quality, such as advanced concept accelerators, free electron lasers, spallalion neutron sources, and future heavy-ion drivers for inertial fusion. The primary focus of this presentation is experimental results in the area of beam steering and control within the injection line and ring. Unique beam steering algorithms now include measurement of the beam response matrix at each quadrupole and matrix inversion by singular value decomposition (SVD). With these advanced steering methods, transport of an intense beam over 50 turns (3600 full lattice periods) of the ring has been achieved.

  13. TOPOLOGY FOR A DSP BASED BEAM CONTROL SYSTEM IN THE AGS BOOSTER.

    SciTech Connect

    DELONG,J.BRENNAN,J.M.HAYES,T.LE,T.N.SMITH,K.

    2003-05-12

    The AGS Booster supports beams of ions and protons with a wide range of energies on a pulse-by-pulse modulation basis. This requires an agile beam control system highly integrated with its controls. To implement this system digital techniques in the form of Digital Signal Processors, Direct Digital Synthesizers, digital receivers and high speed Analog to Digital Converters are used. Signals from the beam and cavity pick-ups, as well as measurements of magnetic field strength in the ring dipoles are processed in real time. To facilitate this a multi-processor topology with high bandwidth data links is being designed.

  14. Array designs for amplitude and phase control of millimeter-wave beams

    NASA Astrophysics Data System (ADS)

    Sjogren, L. B.; Liu, H.-X. L.; Qin, X.-H.; Domier, C. W.; Luhmann, N. C., Jr.

    1993-08-01

    New array design concepts are described for the phase and amplitude control of millimeter and submillimeter-wave beams. Phase shifter array designs providing increased phase range and wider bandwidth are described. Techniques involving the integration of gain-producing elements as well as tuning elements on a single array are proposed for application to high-performance beam control and beam shaping. These concepts should facilitate the further development of quasi-optical solid state device-based arrays for application to millimeter-wave electronic systems.

  15. National Ignition Facility, subsystem design requirements beam control {ampersand} laser diagnostics SSDR 1.7

    SciTech Connect

    Bliss, E.

    1996-11-01

    This Subsystem Design Requirement document is a development specification that establishes the performance, design, development, and test requirements for the Alignment subsystem (WBS 1.7.1), Beam Diagnostics (WBS 1.7.2), and the Wavefront Control subsystem (WBS 1.7. 3) of the NIF Laser System (WBS 1.3). These three subsystems are collectively referred to as the Beam Control & Laser Diagnostics Subsystem. The NIF is a multi-pass, 192-beam, high-power, neodymium-glass laser that meets requirements set forth in the NIF SDR 002 (Laser System). 3 figs., 3 tabs.

  16. Summary report of working group 5: Beam and radiation generation, monitoring, and control

    SciTech Connect

    Church, Mike; Kim, Ki-Yong; /Maryland U.

    2010-01-01

    This paper summarizes the activities and presentations of Working Group 5 of the Advanced Accelerator Concepts Workshop held at Annapolis, Maryland in June 2010. Working Group 5 touched on a broad range of topics in the fields of beam and radiation generation and their monitoring and control. These topics were not comprehensively covered in this Workshop, but rather the Working Group concentrated on specific new developments and recent investigations. The Working Group divided its sessions into four broad categories: cathodes and electron guns, radiation generation, beam diagnostics, and beam control and dynamics. This summary is divided into the same structure.

  17. Simulation and Modeling of a New Medium Access Control Scheme for Multi-Beam Directional Networking

    DTIC Science & Technology

    2017-03-03

    Simulation and Modeling of a New Medium Access Control Scheme for Multi-Beam Directional Networking Brian Proulx, Greg Kuperman, Nathaniel M. Jones...paper, we analyze a new medium access control (MAC) protocol for multi-beam directional network via high- fidelity simulation using a real-time emulator...implement our protocol in both simula- tion and a new Extendable Mobile Ad-hoc Network Emula- tor (EMANE) model that allows for real-time, high fidelity

  18. Control of quasi-monoenergetic electron beams from laser-plasma accelerators

    NASA Astrophysics Data System (ADS)

    Tsai, H.-E.; Swanson, K. K.; Barber, S. K.; Mao, H.-S.; Lehe, R.; Steinke, S.; van Tilborg, J.; Geddes, C. G. R.; Leemans, W. P.

    2017-03-01

    In this paper, we demonstrate a highly tunable, controlled-injection laser-plasma accelerator (LPA) through systematically varying parameters of a density shock injector. Beam energy, energy spread, charge and pointing can be controlled in the range of 50-300 MeV, with <10% energy spread, 1.5 mrad divergence and <1 mrad pointing fluctuation. The beams are repeatable, and suitable for high quality MeV Thomson photon sources or for injectors to staged systems.

  19. The analysis and large-angle control of a flexible beam using an adaptive truss

    NASA Technical Reports Server (NTRS)

    Warrington, Thomas J.; Clark, William W.; Robertshaw, Harry H.; Horner, C. Garnett

    1991-01-01

    This preliminary study of an adaptive truss slewing problem investigates the static positioning of an adaptive truss at slewed orientations and the dynamic vibrations of an attached flexible beam. A nonlinear model of an adaptive truss and flexible beam is derived. Linear control laws are developed and simulated for various truss configurations. Results show the linear control laws developed at a slewed configuration perform best at that configuration.

  20. Automatic beam position control at Los Alamos Spallation Radiation Effects Facility (LASREF)

    SciTech Connect

    Oothoudt, M.; Pillai, C.; Zumbro, M.

    1997-08-01

    Historically the Los Alamos Spallation Radiation Effects Facility (LASREF) has used manual methods to control the position of the 800 kW, 800 MeV proton beam on targets. New experiments, however, require more stringent position control more frequently than can be done manually for long periods of time. Data from an existing harp is used to automatically adjust steering magnets to maintain beam position to required tolerances.

  1. Fluid loss control additives for oil well cementing compositions

    SciTech Connect

    Crema, S.C.; Kucera, C.H.

    1992-03-03

    This patent describes a cementing composition useful in cementing oil, gas and water wells. It comprises hydraulic cement; and a fluid loss additive in an amount effective to reduce fluid loss, the fluid loss additive comprised of a copolymer of acrylamide monomer and vinyl formamide monomer and derivatives thereof in a weight percent ratio of from about 95:5 to 5:95, the copolymer having a molecular weight range of from about 10,000 to 3,000,000, the acrylamide monomer being selected from the group consisting of acrylamide, methacrylamide, N,N-dimethyl(meth)acrylamide, dialkylaminoalkyl(meth) acrylamide and mixtures thereof, the vinyl formamide monomer being selected from the group consisting of vinyl formamide, its hydrolysis products and derivatives thereof.

  2. Future Integrated Systems Concept for Preventing Aircraft Loss-of-Control Accidents

    NASA Technical Reports Server (NTRS)

    Belcastro, Christine M.; Jacobson, Steven r.

    2010-01-01

    Loss of control remains one of the largest contributors to aircraft fatal accidents worldwide. Aircraft loss-of-control accidents are highly complex in that they can result from numerous causal and contributing factors acting alone or (more often) in combination. Hence, there is no single intervention strategy to prevent these accidents. This paper presents future system concepts and research directions for preventing aircraft loss-of-control accidents.

  3. High Performance Open Loop Control of Scanning with a Small Cylindrical Cantilever Beam.

    PubMed

    Kundrat, Matthew J; Reinhall, Per G; Lee, Cameron M; Seibel, Eric J

    2011-04-11

    The steady state response motion of a base excited cantilever beam with circular cross-section excited by a unidirectional displacement will fall along a straight line. However, achieving straight-line motion with a real cantilever beam of circular cross-section is difficult to accomplish. This is due to the fact that nonlinear effects, small deviations from circularity, asymmetric boundary conditions, and actuator cross coupling can induce whirling. The vast majority of previous work on cantilever beam whirling has focused on the effects of system nonlinearities. We show that whirling is a much broader problem in the design of resonant beam scanners in that the onset of whirling does not depend on large amplitude of motion. Rather, whirling is the norm in real systems due to small system asymmetries and actuator cross coupling. It is therefore necessary to control the growth of the whirling motion when a unidirectional beam motion is desired. We have developed a novel technique to identify the two eigen directions of the beam. Base excitation generated by virtual electrodes along these orthogonal eigen axes of the cantilever beam system generates tip vibration without whirl. This leads to accurate open loop control of the motion of the beam through the combined actuation of two pairs of orthogonally placed actuator electrodes.

  4. Controlled-Shape, Ultrasonic-Angle-Beam Standard Reflector

    NASA Technical Reports Server (NTRS)

    Berry, J., Robertf.

    1986-01-01

    New ultrasonic angle-beam standard reflector uses impression of letter "l" steel-die stamp. NDE techniques and standard reflector apply to use of pulse-echo-type ultrasonic equipment for inspection of wrought metals including forgings and forging stock; rolled billet, bar or plate; and extruded bar, tube, and shapes. "l" reference standard reflector affords advantages of easy insertion in inspected item using common hand-tools and greatly reduced implementation time through elimination of machining operations.

  5. Applying CLIPS to control of molecular beam epitaxy processing

    NASA Technical Reports Server (NTRS)

    Rabeau, Arthur A.; Bensaoula, Abdelhak; Jamison, Keith D.; Horton, Charles; Ignatiev, Alex; Glover, John R.

    1990-01-01

    A key element of U.S. industrial competitiveness in the 1990's will be the exploitation of advanced technologies which involve low-volume, high-profit manufacturing. The demands of such manufacture limit participation to a few major entities in the U.S. and elsewhere, and offset the lower manufacturing costs of other countries which have, for example, captured much of the consumer electronics market. One such technology is thin-film epitaxy, a technology which encompasses several techniques such as Molecular Beam Epitaxy (MBE), Chemical Beam Epitaxy (CBE), and Vapor-Phase Epitaxy (VPE). Molecular Beam Epitaxy (MBE) is a technology for creating a variety of electronic and electro-optical materials. Compared to standard microelectronic production techniques (including gaseous diffusion, ion implantation, and chemical vapor deposition), MBE is much more exact, though much slower. Although newer than the standard technologies, MBE is the technology of choice for fabrication of ultraprecise materials for cutting-edge microelectronic devices and for research into the properties of new materials.

  6. Contamination control in ion beam sputter-deposited films

    NASA Astrophysics Data System (ADS)

    Pearson, David I. C.; Pochon, Sebastien; Cooke, Mike

    2013-09-01

    The conventional wisdom to guarantee high purity thin films in IBSD has been to use a large vacuum chamber usually in excess of 1 m3. The chamber size was important to minimise the effect of reflected high energy particles from the target surface sputtering chamber materials onto the substrate and to allow the use of large targets to avoid beam overspill onto chamber furniture. An improved understanding of beam trajectories and re-sputtered material paths has allowed the deposition of thin films with very low metallic impurity content in a chamber volume below 0.5 m3. Thus, by optimizing the sputter ion source, target and substrate configuration, and by arranging suitable shielding made of an appropriate material in the process chamber, the levels of contaminants in the deposited films have been reduced to a minimum. With this optimum hardware arrangement, the ion beam process parameters were then optimized with respect to the ppm levels of contaminants measured in the films by SIMS analysis. Using the deposition of SiO2 as a standard material for DSIMS composition analysis and impurity level determination, it has been shown that our IBS deposition tool is capable of depositing films with contamination levels of <50ppm for the total of all metal impurities in the deposited films.

  7. Monolithic millimeter-wave diode array beam controllers: Theory and experiment

    NASA Technical Reports Server (NTRS)

    Sjogren, L. B.; Liu, H.-X. L.; Wang, F.; Liu, T.; Wu, W.; Qin, X.-H.; Chung, E.; Domier, C. W.; Luhmann, N. C., Jr.; Maserjian, J.

    1992-01-01

    In the current work, multi-function beam control arrays have been fabricated and have successfully demonstrated amplitude control of transmitted beams in the W and D bands (75-170 GHz). While these arrays are designed to provide beam control under DC bias operation, new designs for high-speed electronic and optical control are under development. These arrays will fill a need for high-speed watt-level beam switches in pulsed reflectometer systems under development for magnetic fusion plasma diagnostics. A second experimental accomplishment of the current work is the demonstration in the 100-170 GHz (D band) frequency range of a new technique for the measurement of the transmission phase as well as amplitude. Transmission data can serve as a means to extract ('de-embed') the grid parameters; phase information provides more complete data to assist in this process. Additional functions of the array beam controller yet to be tested include electronically controlled steering and focusing of a reflected beam. These have application in the areas of millimeter-wave electronic scanning radar and reflectometry, respectively.

  8. Development of a Computer Control System for Heavy Ion Beam Probes

    NASA Astrophysics Data System (ADS)

    Andersen, J. K.; Roberts, S. L.; Westervelt, E. R.; Schoch, P. M.; Schatz, J. G.

    1996-11-01

    Enhanced computer control of heavy ion beam probes would increase the reproducability of experimental conditions by automation and feedback control of some system parameters. Also, operation from a remote site would then be feasible. Computer control has been implemented on a variety of Rensselaer heavy ion beam probe systems. However, no system to date has allowed complete remote operation. This has been primarily due to the limitations of the user interface. The next generation of HIBP control systems software is being created with National Instruments' graphical language, LabVIEW. The virtual instruments allow detailed monitoring and control of the injected beam conditions. The control and monitoring of the ion beam, including filament current and Pierce, focusing, quadrupole lens, and sweep electrodes' voltages has been tested on RPI's vertical test stand. A feedback routine to focus the beam using the quadrupole lens is currently being developed. When this capability is available, it will be implemented on a heavy ion beam probe diagnostic operating on a magnetic confinement device.

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

    SciTech Connect

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

    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.

  10. Sub-nanoradiant beam pointing monitoring and stabilization system for controlling input beam jitter in gravitational wave interferometers.

    PubMed

    Canuel, B; Genin, E; Mantovani, M; Marque, J; Ruggi, P; Tacca, M

    2014-05-01

    In this paper, a simple and effective control system to monitor and suppress the beam jitter noise at the input of an optical system, called a beam pointing control (BPC) system, will be described, showing the theoretical principle and an experimental demonstration for the application of large-scale gravitational wave (GW) interferometers (ITFs), in particular for the Advanced Virgo detector. For this purpose, the requirements for the control accuracy and the sensing noise will be computed by taking into account the Advanced Virgo optical configuration, and the outcomes will be compared with the experimental measurement obtained in the laboratory. The system has shown unprecedented performance in terms of control accuracy and sensing noise. The BPC system has achieved a control accuracy of ~10⁻⁸ rad for the tilt and ~10⁻⁷ m for the shift and a sensing noise of less than 1 n  rad/√Hz, which is compliant with the Advanced Virgo GW ITF requirements.

  11. EVALUATION OF NANOFILTRATION PRETREATMENTS FOR FLUX LOSS CONTROL.

    EPA Science Inventory

    The loss of membrane flux due to fouling is a major impediment to the development of membrane processes for use in drinking water treatment. The objective of this work was to evaluate fouling in nanofiltration (NF) pilot systems fed conventionally-treated (coagulation/sedimentati...

  12. EVALUATION OF NANOFILTRATION PRETREATMENTS FOR FLUX LOSS CONTROL.

    EPA Science Inventory

    The loss of membrane flux due to fouling is a major impediment to the development of membrane processes for use in drinking water treatment. The objective of this work was to evaluate fouling in nanofiltration (NF) pilot systems fed conventionally-treated (coagulation/sedimentati...

  13. Mars Express observations of high altitude planetary ion beams and their relation to the "energetic plume" loss channel

    NASA Astrophysics Data System (ADS)

    Liemohn, Michael W.; Johnson, Blake C.; Fränz, Markus; Barabash, Stas

    2014-12-01

    This study presents observational evidence of high-energy (ions >2 keV) beams of planetary ions above Mars' induced magnetospheric boundary (IMB) and relates them with the energetic plume loss channel calculated from numerical models. A systematic search of the Mars Express (MEX) ion data using an orbit filtering criteria is described, using magnetometer data from Mars Global Surveyor (MGS) to determine the solar wind motional electric field (Esw) direction. Two levels of statistical survey are presented, one focused on times when the MEX orbit was directly in line with the Esw and another for all angles between the MEX location and the Esw. For the first study, within the 3 year overlap of MGS and MEX, nine brief intervals were found with clear and unambiguous high-energy O+ observations consistent with the energetic plume loss channel. The second survey used a point-by-point determination of MEX relative to the E-field and contained many thousands of 192 s measurements. This study yielded only a weak indication for an Esw-aligned plume. Furthermore, the y-z components of the weighted average velocities in the bins of this y-z spatial domain survey do not systematically point in the Esw direction. The first survey implies the existence of this plume and shows that its characteristics are seemingly consistent with the expected energy and flight direction from numerical studies; the second study softens the finding and demonstrates that there are many planetary ions beyond the IMB moving in unexpected directions. Several possible explanations for this discrepancy are discussed.

  14. Test and control computer user's guide for a digital beam former test system

    NASA Technical Reports Server (NTRS)

    Alexovich, Robert E.; Mallasch, Paul G.

    1992-01-01

    A Digital Beam Former Test System was developed to determine the effects of noise, interferers and distortions, and digital implementations of beam forming as applied to the Tracking and Data Relay Satellite 2 (TDRS 2) architectures. The investigation of digital beam forming with application to TDRS 2 architectures, as described in TDRS 2 advanced concept design studies, was conducted by the NASA/Lewis Research Center for NASA/Goddard Space Flight Center. A Test and Control Computer (TCC) was used as the main controlling element of the digital Beam Former Test System. The Test and Control Computer User's Guide for a Digital Beam Former Test System provides an organized description of the Digital Beam Former Test System commands. It is written for users who wish to conduct tests of the Digital Beam forming Test processor using the TCC. The document describes the function, use, and syntax of the TCC commands available to the user while summarizing and demonstrating the use of the commands wtihin DOS batch files.

  15. High trait self-control predicts positive health behaviors and success in weight loss

    PubMed Central

    Crescioni, A. Will; Ehrlinger, Joyce; Alquist, Jessica L.; Conlon, Kyle E.; Baumeister, Roy F.; Schatschneider, Christopher; Dutton, Gareth R.

    2015-01-01

    Surprisingly few studies have explored the intuitive connection between self-control and weight loss. We tracked participants’ diet, exercise and weight loss during a 12-week weight loss program. Participants higher in self-control weighed less and reported exercising more than their lower self-control counterparts at baseline. Independent of baseline differences, individuals high in dispositional self-control ate fewer calories overall and fewer calories from fat, burned marginally more calories through exercise, and lost more weight during the program than did those lower in self-control. These data suggest that trait self-control is, indeed, an important predictor of health behaviors. PMID:21421645

  16. Ammonia Volatilization Losses from Paddy Fields under Controlled Irrigation with Different Drainage Treatments

    PubMed Central

    He, Yupu; Yang, Shihong; Wang, Yijiang

    2014-01-01

    The effect of controlled drainage (CD) on ammonia volatilization (AV) losses from paddy fields under controlled irrigation (CI) was investigated by managing water table control levels using a lysimeter. Three drainage treatments were implemented, namely, controlled water table depth 1 (CWT1), controlled water table depth 2 (CWT2), and controlled water table depth 3 (CWT3). As the water table control levels increased, irrigation water volumes in the CI paddy fields decreased. AV losses from paddy fields reduced due to the increases in water table control levels. Seasonal AV losses from CWT1, CWT2, and CWT3 were 59.8, 56.7, and 53.0 kg N ha−1, respectively. AV losses from CWT3 were 13.1% and 8.4% lower than those from CWT1 and CWT2, respectively. A significant difference in the seasonal AV losses was confirmed between CWT1 and CWT3. Less weekly AV losses followed by TF and PF were also observed as the water table control levels increased. The application of CD by increasing water table control levels to a suitable level could effectively reduce irrigation water volumes and AV losses from CI paddy fields. The combination of CI and CD may be a feasible water management method of reducing AV losses from paddy fields. PMID:24741349

  17. Vibration Control Of A Flexible Beam Using A Rotational Internal Resonance Controller, Part I: Theoretical Development And Analysis

    NASA Astrophysics Data System (ADS)

    Tuer, K. L.; Duquette, A. P.; Golnaraghi, M. F.

    1993-10-01

    In this paper, an unconventional technique to control the vibrations of a cantilevered flexible beam, based on a non-linear dynamics phenomenon known as internal resonance , is proposed. The controller consists of a DC motor, itself a part of a simple regulated feedback system, with a rigid beam/tip mass configuration attached to the motor shaft. The addition of the controller to the tip of the flexible beam introduces quadratic, dynamic non-linearities into an otherwise linear system. Under the proper circumstances, these non-linearities can be used to generate a coupling effect between the modes of vibration of the system.An internally resonant state exists if the equations of motion are characterized by frequency-amplitude interactions and the first two natural frequencies of the linear portion of the non-linear equations of motion are commensurable or nearly commensurable. Once a resonance condition is established, a transfer of energy transpires between the modes of vibration. Thus, due to modal coupling, energy is, in effect, transferred from the flexible beam to the secondary beam, where it is dissipated through velocity feedback of the motor.Theoretical analysis predicts that the planar oscillations of a cantilevered beam displaced at its tip a distance equal to 18 percent of its length can be reduced to a relatively small amplitude in approximately four cycles. This controller has proven to be most effective in controlling large amplitude, low frequency oscillations which are typical for large flexible structures.

  18. Active suppression of nonlinear composite beam vibrations by selected control algorithms

    NASA Astrophysics Data System (ADS)

    Warminski, Jerzy; Bochenski, Marcin; Jarzyna, Wojciech; Filipek, Piotr; Augustyniak, Michal

    2011-05-01

    This paper is focused on application of different control algorithms for a flexible, geometrically nonlinear beam-like structure with Macro Fiber Composite (MFC) actuator. Based on the mathematical model of a geometrically nonlinear beam, analytical solutions for Nonlinear Saturation Controller (NSC) are obtained using Multiple Scale Method. Effectiveness of different control strategies is evaluated by numerical simulations in Matlab-Simulink software. Then, the Digital Signal Processing (DSP) controller and selected control algorithms are implemented to the physical system to compare numerical and experimental results. Detailed analysis for the NSC system is carried out, especially for high level of amplitude and wide range of frequencies of excitation. Finally, the efficiency of the considered controllers is tested experimentally for a more complex autoparametric " L-shape" beam system.

  19. Method and system for controlling the position of a beam of light

    DOEpatents

    Steinkraus, Jr., Robert F.; Johnson, Gary W [Livermore, CA; Ruggiero, Anthony J [Livermore, CA

    2011-08-09

    An method and system for laser beam tracking and pointing is based on a conventional position sensing detector (PSD) or quadrant cell but with the use of amplitude-modulated light. A combination of logarithmic automatic gain control, filtering, and synchronous detection offers high angular precision with exceptional dynamic range and sensitivity, while maintaining wide bandwidth. Use of modulated light enables the tracking of multiple beams simultaneously through the use of different modulation frequencies. It also makes the system resistant to interfering light sources such as ambient light. Beam pointing is accomplished by feeding back errors in the measured beam position to a beam steering element, such as a steering mirror. Closed-loop tracking performance is superior to existing methods, especially under conditions of atmospheric scintillation.

  20. Recent improvements to the DIII-D neutral beam instrumentation and control system

    SciTech Connect

    Kellman, D.H.; Hong, R.

    1997-11-01

    The DIII-D neutral beam (NB) instrumentation and control (I and C) system provides for operational control and synchronization of the eight DIII-D neutral beam injection systems, as well as for pertinent data acquisition and safety interlocking. Recently, improvements were made to the I and C system. With the replacement of the NB control computers, new signal interfacing was required to accommodate the elimination of physical operator panels, in favor of graphical user interface control pages on computer terminal screens. The program in the mode control (MC) programmable logic controller (PLC), which serves as a logic-processing interface between the NB control computers and system hardware, was modified to improve the availability of NB heating of DIII-D plasmas in the event that one or more individual beam systems suddenly become unavailable while preparing for a tokamak experimental shot sequences. An upgraded computer platform was adopted for the NB control system operator interface and new graphical user interface pages were developed to more efficiently display system status data. A failure mode of the armor tile infrared thermometers (pyrometers), which serve to terminate beam pulsing if beam shine-through overheats wall thermal shielding inside the DIII-D tokamak, was characterized such that impending failures can be detected and repairs effected to mitigate beam system down-time. The hardware that controls gas flow to the beamline neutralizer cells was upgraded to reduce susceptibility to electromagnetic interference (EMI), and interlocking was provided to terminate beam pulsing in the event of insufficient neutralizer gas flow. Motivation, implementation, and results of these improvements are presented.

  1. Measurement of Absolute Excitation Cross Sections in Highly-Charged Ions Using Electron Energy Loss and Merged Beams

    NASA Technical Reports Server (NTRS)

    Chutjian, A.; Smith, Steven J.; Lozano, J.

    2002-01-01

    There is increasing emphasis during this decade on understanding energy balance and phenomena observed in high electron temperature plasmas. The UV spectral return from FUSE, the X-ray spectral return from the HETG on Chandra and the LETGS 011 XMM-Newton are just beginning. Line emissions are almost entirely from highly-charged ions (HCIs) of C, N, 0, Ne, Mg, S, Si, Ca, and Fe. The Constellation-X mission will provide X-ray spectroscopy up to photon energies of 0.12 nm (10 keV) where primary line emitters will be HCIs. A variety of atomic parameters are required to model the stellar and solar plasma. These include cross sections for excitation, ionization, charge-exchange, X-ray emission, direct and indirect recombination, lifetimes and branching ratios, and dependences on l, m mixing by external E and B fields. In almost all cases the atomic quantities are calculated, and few comparisons to experiment have been carried out. Collision strengths and Einstein A-values are required to convert the observed spectral intensities to electron temperatures and densities in the stellar plasma. The JPL electron energy-loss and merged beam approach has been used to measure absolute collision strengths in a number of ions, with critical comparison made to the best available theories.

  2. Phase control of the microwave radiation in free electron laser two-beam accelerator

    SciTech Connect

    Goren, Y.; Sessler, A.M.

    1987-07-01

    A phase control system for the FEL portion of Two-Beam Accelerator is proposed. The control keeps the phase error within acceptable bounds. The control mechanism is analyzed, both analytically in a ''resonant particle'' approximation and numerically in a multi-particle simulation code. Sensitivity of phase errors to the FEL parameters has been noticed.

  3. Active vibration control for piezoelectricity cantilever beam: an adaptive feedforward control method

    NASA Astrophysics Data System (ADS)

    Zhu, Qiao; Yue, Jun-Zhou; Liu, Wei-Qun; Wang, Xu-Dong; Chen, Jun; Hu, Guang-Di

    2017-04-01

    This work is focused on the active vibration control of piezoelectric cantilever beam, where an adaptive feedforward controller (AFC) is utilized to reject the vibration with unknown multiple frequencies. First, the experiment setup and its mathematical model are introduced. Due to that the channel between the disturbance and the vibration output is unknown in practice, a concept of equivalent input disturbance (EID) is employed to put an equivalent disturbance into the input channel. In this situation, the vibration control can be achieved by setting the control input be the identified EID. Then, for the EID with known multiple frequencies, the AFC is introduced to perfectly reject the vibration but is sensitive to the frequencies. In order to accurately identify the unknown frequencies of EID in presence of the random disturbances and un-modeled nonlinear dynamics, the time-frequency-analysis (TFA) method is employed to precisely identify the unknown frequencies. Consequently, a TFA-based AFC algorithm is proposed to the active vibration control with unknown frequencies. Finally, four cases are given to illustrate the efficiency of the proposed TFA-based AFC algorithm by experiment.

  4. ISS Contingency Attitude Control Recovery Method for Loss of Automatic Thruster Control

    NASA Technical Reports Server (NTRS)

    Bedrossian, Nazareth; Bhatt, Sagar; Alaniz, Abran; McCants, Edward; Nguyen, Louis; Chamitoff, Greg

    2008-01-01

    In this paper, the attitude control issues associated with International Space Station (ISS) loss of automatic thruster control capability are discussed and methods for attitude control recovery are presented. This scenario was experienced recently during Shuttle mission STS-117 and ISS Stage 13A in June 2007 when the Russian GN&C computers, which command the ISS thrusters, failed. Without automatic propulsive attitude control, the ISS would not be able to regain attitude control after the Orbiter undocked. The core issues associated with recovering long-term attitude control using CMGs are described as well as the systems engineering analysis to identify recovery options. It is shown that the recovery method can be separated into a procedure for rate damping to a safe harbor gravity gradient stable orientation and a capability to maneuver the vehicle to the necessary initial conditions for long term attitude hold. A manual control option using Soyuz and Progress vehicle thrusters is investigated for rate damping and maneuvers. The issues with implementing such an option are presented and the key issue of closed-loop stability is addressed. A new non-propulsive alternative to thruster control, Zero Propellant Maneuver (ZPM) attitude control method is introduced and its rate damping and maneuver performance evaluated. It is shown that ZPM can meet the tight attitude and rate error tolerances needed for long term attitude control. A combination of manual thruster rate damping to a safe harbor attitude followed by a ZPM to Stage long term attitude control orientation was selected by the Anomaly Resolution Team as the alternate attitude control method for such a contingency.

  5. Spillover Effects of Loss of Control on Risky Decision-Making.

    PubMed

    Beisswingert, Birgit M; Zhang, Keshun; Goetz, Thomas; Fischbacher, Urs

    2016-01-01

    Decision making in risky situations is frequently required in our everyday lives and has been shown to be influenced by various factors, some of which are independent of the risk context. Based on previous findings and theories about the central role of perceptions of control and their impact on subsequent settings, spillover effects of subjective loss of control on risky decision-making are assumed. After developing an innovative experimental paradigm for inducing loss of control, its hypothesized effects on risky decision-making are investigated. Partially supporting the hypotheses, results demonstrated no increased levels of risk perceptions but decreased risk-taking behavior following experiences of loss of control. Thus, this study makes a methodological contribution by proposing a newly developed experimental paradigm facilitating further research on the effects of subjective loss of control, and additionally provides partial evidence for the spillover effects of loss of control experiences on risky decision-making.

  6. Spillover Effects of Loss of Control on Risky Decision-Making

    PubMed Central

    Beisswingert, Birgit M.; Zhang, Keshun; Goetz, Thomas; Fischbacher, Urs

    2016-01-01

    Decision making in risky situations is frequently required in our everyday lives and has been shown to be influenced by various factors, some of which are independent of the risk context. Based on previous findings and theories about the central role of perceptions of control and their impact on subsequent settings, spillover effects of subjective loss of control on risky decision-making are assumed. After developing an innovative experimental paradigm for inducing loss of control, its hypothesized effects on risky decision-making are investigated. Partially supporting the hypotheses, results demonstrated no increased levels of risk perceptions but decreased risk-taking behavior following experiences of loss of control. Thus, this study makes a methodological contribution by proposing a newly developed experimental paradigm facilitating further research on the effects of subjective loss of control, and additionally provides partial evidence for the spillover effects of loss of control experiences on risky decision-making. PMID:26930066

  7. Controlling fast-electron-beam divergence using two laser pulses.

    PubMed

    Scott, R H H; Beaucourt, C; Schlenvoigt, H-P; Markey, K; Lancaster, K L; Ridgers, C P; Brenner, C M; Pasley, J; Gray, R J; Musgrave, I O; Robinson, A P L; Li, K; Notley, M M; Davies, J R; Baton, S D; Santos, J J; Feugeas, J-L; Nicolaï, Ph; Malka, G; Tikhonchuk, V T; McKenna, P; Neely, D; Rose, S J; Norreys, P A

    2012-07-06

    This Letter describes the first experimental demonstration of the guiding of a relativistic electron beam in a solid target using two colinear, relativistically intense, picosecond laser pulses. The first pulse creates a magnetic field that guides the higher-current, fast-electron beam generated by the second pulse. The effects of intensity ratio, delay, total energy, and intrinsic prepulse are examined. Thermal and Kα imaging show reduced emission size, increased peak emission, and increased total emission at delays of 4-6 ps, an intensity ratio of 10∶1 (second:first) and a total energy of 186 J. In comparison to a single, high-contrast shot, the inferred fast-electron divergence is reduced by 2.7 times, while the fast-electron current density is increased by a factor of 1.8. The enhancements are reproduced with modeling and are shown to be due to the self-generation of magnetic fields. Such a scheme could be of considerable benefit to fast-ignition inertial fusion.

  8. Dynamic Beam Solutions for Real-Time Simulation and Control Development of Flexible Rockets

    NASA Technical Reports Server (NTRS)

    Su, Weihua; King, Cecilia K.; Clark, Scott R.; Griffin, Edwin D.; Suhey, Jeffrey D.; Wolf, Michael G.

    2016-01-01

    In this study, flexible rockets are structurally represented by linear beams. Both direct and indirect solutions of beam dynamic equations are sought to facilitate real-time simulation and control development for flexible rockets. The direct solution is completed by numerically integrate the beam structural dynamic equation using an explicit Newmark-based scheme, which allows for stable and fast transient solutions to the dynamics of flexile rockets. Furthermore, in the real-time operation, the bending strain of the beam is measured by fiber optical sensors (FOS) at intermittent locations along the span, while both angular velocity and translational acceleration are measured at a single point by the inertial measurement unit (IMU). Another study in this paper is to find the analytical and numerical solutions of the beam dynamics based on the limited measurement data to facilitate the real-time control development. Numerical studies demonstrate the accuracy of these real-time solutions to the beam dynamics. Such analytical and numerical solutions, when integrated with data processing and control algorithms and mechanisms, have the potential to increase launch availability by processing flight data into the flexible launch vehicle's control system.

  9. Ion-beam apparatus and method for analyzing and controlling integrated circuits

    DOEpatents

    Campbell, Ann N.; Soden, Jerry M.

    1998-01-01

    An ion-beam apparatus and method for analyzing and controlling integrated circuits. The ion-beam apparatus comprises a stage for holding one or more integrated circuits (ICs); a source means for producing a focused ion beam; and a beam-directing means for directing the focused ion beam to irradiate a predetermined portion of the IC for sufficient time to provide an ion-beam-generated electrical input signal to a predetermined element of the IC. The apparatus and method have applications to failure analysis and developmental analysis of ICs and permit an alteration, control, or programming of logic states or device parameters within the IC either separate from or in combination with applied electrical stimulus to the IC for analysis thereof. Preferred embodiments of the present invention including a secondary particle detector and an electron floodgun further permit imaging of the IC by secondary ions or electrons, and allow at least a partial removal or erasure of the ion-beam-generated electrical input signal.

  10. Ion-beam apparatus and method for analyzing and controlling integrated circuits

    DOEpatents

    Campbell, A.N.; Soden, J.M.

    1998-12-01

    An ion-beam apparatus and method for analyzing and controlling integrated circuits are disclosed. The ion-beam apparatus comprises a stage for holding one or more integrated circuits (ICs); a source means for producing a focused ion beam; and a beam-directing means for directing the focused ion beam to irradiate a predetermined portion of the IC for sufficient time to provide an ion-beam-generated electrical input signal to a predetermined element of the IC. The apparatus and method have applications to failure analysis and developmental analysis of ICs and permit an alteration, control, or programming of logic states or device parameters within the IC either separate from or in combination with applied electrical stimulus to the IC for analysis thereof. Preferred embodiments of the present invention including a secondary particle detector and an electron floodgun further permit imaging of the IC by secondary ions or electrons, and allow at least a partial removal or erasure of the ion-beam-generated electrical input signal. 4 figs.

  11. Ion beam machining error control and correction for small scale optics.

    PubMed

    Xie, Xuhui; Zhou, Lin; Dai, Yifan; Li, Shengyi

    2011-09-20

    Ion beam figuring (IBF) technology for small scale optical components is discussed. Since the small removal function can be obtained in IBF, it makes computer-controlled optical surfacing technology possible to machine precision centimeter- or millimeter-scale optical components deterministically. Using a small ion beam to machine small optical components, there are some key problems, such as small ion beam positioning on the optical surface, material removal rate, ion beam scanning pitch control on the optical surface, and so on, that must be seriously considered. The main reasons for the problems are that it is more sensitive to the above problems than a big ion beam because of its small beam diameter and lower material ratio. In this paper, we discuss these problems and their influences in machining small optical components in detail. Based on the identification-compensation principle, an iterative machining compensation method is deduced for correcting the positioning error of an ion beam with the material removal rate estimated by a selected optimal scanning pitch. Experiments on ϕ10 mm Zerodur planar and spherical samples are made, and the final surface errors are both smaller than λ/100 measured by a Zygo GPI interferometer.

  12. Vertical Beam Angle Control: an Advancement/Requirement in Modern Ion Implant Manufacturing

    SciTech Connect

    Krueger, Christian; Rathmell, Robert; Kamenitsa, Dennis; Krimbacher, Bernhard

    2008-11-03

    As the industry moves to the new technology nodes of 45 nm and 32 nm devices, implant angle control becomes even more crucial for consistent device performance. Commercial single wafer ion implanters are able to measure and correct the horizontal incident angle of the ion beam. But the vertical beam angle (VBA) control has become a very important parameter as well. In this work the authors demonstrate the impact of a tilt variation for a 65 nm and a 45 nm MOS transistor generated by different beam setups on one machine. Comparisons are made for each technology with a controlled angle variation of {+-}4 deg. The Vt-distribution should be reduced with better incident angle control allowing faster development of a new transistor node base line using the new VBA control technique from Axcelis.

  13. Vertical Beam Angle Control: an Advancement/Requirement in Modern Ion Implant Manufacturing

    NASA Astrophysics Data System (ADS)

    Krueger, Christian; Rathmell, Robert; Kamenitsa, Dennis; Krimbacher, Bernhard

    2008-11-01

    As the industry moves to the new technology nodes of 45 nm and 32 nm devices, implant angle control becomes even more crucial for consistent device performance. Commercial single wafer ion implanters are able to measure and correct the horizontal incident angle of the ion beam. But the vertical beam angle (VBA) control has become a very important parameter as well. In this work the authors demonstrate the impact of a tilt variation for a 65 nm and a 45 nm MOS transistor generated by different beam setups on one machine. Comparisons are made for each technology with a controlled angle variation of ±4°. The Vt-distribution should be reduced with better incident angle control allowing faster development of a new transistor node base line using the new VBA control technique from Axcelis.

  14. Vibration control of an Euler-Bernoulli beam under unknown spatiotemporally varying disturbance

    NASA Astrophysics Data System (ADS)

    Ge, Shuzhi Sam; Zhang, Shuang; He, Wei

    2011-05-01

    In this article, the vibration suppression of an Euler-Bernoulli beam system is considered by using the adaptive boundary control technique. The dynamics of the beam are represented by a partial differential equation and four ordinary differential equations involving functions of both space and time. By using Lyapunov synthesis, the robust boundary control with a disturbance observer is first proposed to suppress the vibration and attenuate the effect of the external disturbances. To compensate for both the system parametric uncertainties and the disturbances uncertainties, the adaptive boundary control is developed. With the proposed boundary control, the state of the beam system is proven to be uniformly ultimately bounded and converge to a small neighbourhood of zero by appropriately choosing the design parameters. The effectiveness of the proposed control is successfully verified by numerical simulations.

  15. A comparison of different models for beam vibrations from the standpoint of control design

    NASA Technical Reports Server (NTRS)

    Morris, K. A.; Vidyasagar, M.

    1990-01-01

    Different models for beam vibrations are analyzed from the standpoint of designing finite-dimensional controllers to stabilize the beam vibrations. A distributed system described by an undamped Euler-Bernoulli equation cannot be stabilized by any finite-dimensional controller, i.e., any controller which can be described an ordinary differential equation with constant coefficients. If viscous damping is included, a similar problem occurs in that all the poles can not be moved to the left of a given vertical line. These negative results should be interpreted as a commentary on the limitations of these models, rather than on the control of real beams. If a Rayleigh damping model is used, a finite-dimensional controller may be designed to move the closed loop system poles essentially as far to the left in the complex plane as desired. This result will also hold for certain hysteresis damping models. This has implications for the settling time of the vibrations.

  16. Precision beam pointing control with jitter attenuation by optical deflector exhibiting dynamic hysteresis in COIL

    NASA Astrophysics Data System (ADS)

    Ma, Yan-Hua; Zhang, Zeng-Bao; Zhang, Zhi-Guo; Liu, Qin; He, Xin; Shi, Wen-Bo; Mao, Jian-Qin; Jin, Yu-Qi

    2015-02-01

    Due to the existence of various disturbances during the lasing process of the chemical oxygen iodine laser (COIL), the optical beam pointing performance is severely degraded. In this paper, an adaptive control methodology is proposed for the precise pointing control of the optical beam with active beam jitter rejection using a giant magnetostrictive optical deflector (GMOD) which exhibits severe dynamic hysteresis nonlinearity. In particular, a least square support vector machine (LS-SVM) based fast compensator is employed to eliminate the dynamic hysteresis without the inverse model construction. Then an improved feedforward adaptive filter is developed to deal with jitter attenuation when the full-coherent reference signal is unavailable. To improve the stability and overall robustness of the controller, especially when a large initial bias exists, a PI controller is placed in parallel with the adaptive filter. Experimental results validate the precise pointing ability of the proposed control method.

  17. Simulations of S-band RF gun with RF beam control

    NASA Astrophysics Data System (ADS)

    Barnyakov, A. M.; Levichev, A. E.; Maltseva, M. V.; Nikiforov, D. A.

    2017-08-01

    The RF gun with RF control is discussed. It is based on the RF triode and two kinds of the cavities. The first cavity is a coaxial cavity with cathode-grid assembly where beam bunches are formed, the second one is an accelerating cavity. The features of such a gun are the following: bunched and relativistic beams in the output of the injector, absence of the back bombarding electrons, low energy spread and short length of the bunches. The scheme of the injector is shown. The electromagnetic field simulation and longitudinal beam dynamics are presented. The possible using of the injector is discussed.

  18. All-fiber phase-control-free coherent-beam combining toward femtosecond-pulse amplification

    NASA Astrophysics Data System (ADS)

    Kambayashi, Yuta; Yoshida, Minoru; Sasaki, Toshiki; Yoshikawa, Masashi

    2017-01-01

    Our present work is to develop an all-fiber coherent-beam-combining system that achieves a high-energy femtosecond-pulse fiber laser beyond pulse energy limits due to the nonlinear effects in fiber amplifiers. Coherent-beam combining (CBC) using optical fibers is technically difficult because the optical phases and the polarizations in the optical fibers fluctuate due to disturbances. We developed an all-fiber passive CBC system that does not need to control optical phases and polarizations that achieved a beam-combining efficiency of 95.9%. The combined output changes of the passive CBC system are the less than 1.0% in full width.

  19. 40 CFR 1060.104 - What running loss emission control requirements apply?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EVAPORATIVE EMISSIONS FROM NEW AND IN-USE NONROAD AND.... (3) Get an approved Executive Order from the California Air Resources Board showing that your system meets applicable running loss standards in California. (c) If you are subject to both running loss and...

  20. 7 CFR 4288.137 - Succession and loss of control of advanced biofuel facilities and production.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 15 2014-01-01 2014-01-01 false Succession and loss of control of advanced biofuel... PROGRAMS Advanced Biofuel Payment Program General Provisions Payment Provisions § 4288.137 Succession and loss of control of advanced biofuel facilities and production. (a) Contract succession. An entity who...

  1. 7 CFR 4288.137 - Succession and loss of control of advanced biofuel facilities and production.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 15 2013-01-01 2013-01-01 false Succession and loss of control of advanced biofuel... PROGRAMS Advanced Biofuel Payment Program General Provisions § 4288.137 Succession and loss of control of advanced biofuel facilities and production. (a) Contract succession. An entity who becomes the eligible...

  2. 7 CFR 4288.137 - Succession and loss of control of advanced biofuel facilities and production.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 15 2012-01-01 2012-01-01 false Succession and loss of control of advanced biofuel... PROGRAMS Advanced Biofuel Payment Program General Provisions § 4288.137 Succession and loss of control of advanced biofuel facilities and production. (a) Contract succession. An entity who becomes the eligible...

  3. Active vibration control of a smart pultruded fiber-reinforced polymer I-beam

    NASA Astrophysics Data System (ADS)

    Song, G.; Qiao, P.; Sethi, V.; Prasad, A.

    2004-08-01

    Advanced and innovative materials and structures are increasingly used in civil infrastructure applications. By combining the advantages of composites and smart sensors and actuators, active or smart composite structures can be created and be efficiently adopted in practical structural applications. This paper presents results on active vibration control of pultruded fiber-reinforced polymer (FRP) composite thin-walled I-beams using smart sensors and actuators. The FRP I-beams are made of E-glass fibers and polyester resins. The FRP I-beam is in a cantilevered configuration. The PZT (lead zirconate titanate) type of piezoelectric ceramic patches are used as smart sensors and actuators. These patches are surface bonded near the cantilevered end of the I-beam. Utilizing results from modal analyses and experimental modal testing, several active vibration control methods, such as position feedback control, strain rate feedback control and lead compensation, are investigated. Experimental results demonstrate that the proposed methods achieve effective vibration control of FRP I-beams. For instance, the modal damping ratio of the strong direction first bending mode increases by more than 1000% with positive position feedback control.

  4. Active vibration control of a smart pultruded fiber-reinforced polymer I-beam

    NASA Astrophysics Data System (ADS)

    Song, Gangbing; Qiao, Pizhong; Sethi, Vineet; Prasad, A.

    2002-06-01

    Advanced and innovative materials and structures are increasingly used in civil infrastructure applications. By combining the advantages of composites and smart sensors and actuators, active or smart composite structures can be created and be efficiently adopted in practical structural applications. This paper presents results of active vibration control of a pultruded fiber-reinforced polymer (FRP) composites thin-walled I-beams using smart sensors and actuators. The FRP I-beams are made of E-glass fibers and polyester resins. The FRP I-beam is in a cantilevered configuration. PZT (Lead zirconate titanate) type of piezoelectric ceramic patches are used as smart sensors and actuators. These patches are surface-bonded near the cantilevered end of the I-beam. Utilizing results from modal analyses and experimental modal testing, several active vibration control methods, such as position feedback control, strain rate feedback control and lead compensator, are investigated. Experimental results demonstrate that the proposed methods achieve effective vibration control of FRP I-beams. For instance, the modal damping ratio of the strong direction first bending mode increases by more than 1000 percent with a positive position feedback control.

  5. Improved rate control for electron-beam evaporation and evaluation of optical performance improvements.

    PubMed

    Gevelber, Michael; Xu, Bing; Smith, Douglas

    2006-03-01

    A new deposition-rate-control and electron-beam-gun (e-gun) strategy was developed that significantly reduces the growth-rate variations for e-beam-deposited SiO2 coatings. The resulting improvements in optical performance are evaluated for multilayer bandpass filters. The adverse effect of uneven silica-source depletion on coating spectral performances during long deposition runs is discussed.

  6. A new environmentally safe crosslinked polymer for fluid-loss control

    SciTech Connect

    Cole, R.C.; Ali, S.A.; Foley, K.A.

    1995-12-31

    The adverse effects of inadequate fluid-loss control associated with gravel-packed completions is well known. Controlling fluid losses to the formation before and after pack placement is critical to ultimately achieving optimum productivity from a given well. This paper introduces a new environmentally safe, crosslinkable polymer that can help achieve abrupt fluid-loss control without the introduction of particulates of any kind. The polymer is a double-derivatized HEC (DDHEC). This paper presents laboratory data on the DDHEC, including physical properties, crosslinking and breaker chemistry, regainable permeability, degree of fluid-loss control, and rheology. In addition, field case histories are presented to document the efficient fluid-loss control and little or no formation damage in moderate to high-permeability formations.

  7. Vibration Control of Sandwich Beams Using Electro-Rheological Fluids

    NASA Astrophysics Data System (ADS)

    Srikantha Phani, A.; Venkatraman, K.

    2003-09-01

    Electro-rheological (ER) fluids are a class of smart materials exhibiting significant reversible changes in their rheological and hence mechanical properties under the influence of an applied electric field. Efforts are in progress to embed ER fluids in various structural elements to mitigate vibration problems. The present work is an experimental investigation of the behaviour of a sandwich beam with ER fluid acting as the core material. A starch-silicone-oil-based ER fluid is used in the present study. Significant improvements in the damping properties are achieved in experiments and the damping contributions by viscous and non-viscous forces are estimated by force-state mapping (FSM) technique. With the increase in electric field across the ER fluid from 0 to 2 kV, an increase of 25-50% in equivalent viscous damping is observed. It is observed that as concentration of starch is increased, the ER effect grows stronger but eventually is overcome by applied stresses.

  8. Automatic Prevention and Recovery of Aircraft Loss-of-Control by a Hybrid Control Approach

    NASA Astrophysics Data System (ADS)

    Zhao, Yue

    In this dissertation, an integrated automatic flight controller for fixed-wing aircraft Loss-of-Control (LOC) Prevention and Recovery (iLOCPR) is designed. The iLOCPR system comprises: (i) a baseline flight controller for six degrees-of-freedom (6DOF) trajectory tracking for nominal flight designed by trajectory linearization, (ii) a bandwidth adaption augmentation to the baseline controller for LOC prevention using the time-varying PD-eigenvalues to trade tracking performance for increased stability margin and robustness in the presence of LOC-prone flight conditions, (iii) a controller reconfiguration for LOC arrest by switching from the trajectory tracking task to the aerodynamic angle tracking in order to recover and maintain healthy flight conditions at the cost of temporarily abandoning the mission trajectory, (iv) a guidance trajectory designer for mission restoration after the successful arrest of a LOC upset, and (v) a supervisory discrete-event-driven Automatic Flight Management System (AFMS) to autonomously coordinate the control modes (i) - (iv). Theoretical analysis and simulation results are shown for the effectiveness of the proposed methods.

  9. A nonlinear OPC technique for laser beam control in turbulent atmosphere

    NASA Astrophysics Data System (ADS)

    Markov, V.; Khizhnyak, A.; Sprangle, P.; Ting, A.; DeSandre, L.; Hafizi, B.

    2013-05-01

    A viable beam control technique is critical for effective laser beam transmission through turbulent atmosphere. Most of the established approaches require information on the impact of perturbations on wavefront propagated waves. Such information can be acquired by measuring the characteristics of the target-scattered light arriving from a small, preferably diffraction-limited, beacon. This paper discusses an innovative beam control approach that can support formation of a tight laser beacon in deep turbulence conditions. The technique employs Brillouin enhanced fourwave mixing (BEFWM) to generate a localized beacon spot on a remote image-resolved target. Formation of the tight beacon doesn't require a wavefront sensor, AO system, or predictive feedback algorithm. Unlike conventional adaptive optics methods which allow wavefront conjugation, the proposed total field conjugation technique is critical for beam control in the presence of strong turbulence and can be achieved by using this non-linear BEFWM technique. The phase information retrieved from the established beacon beam can then be used in conjunction with an AO system to propagate laser beams in deep turbulence.

  10. Multi-beam reflections with flexible control of polarizations by using anisotropic metasurfaces

    NASA Astrophysics Data System (ADS)

    Ma, Hui Feng; Liu, Yan Qing; Luan, Kang; Cui, Tie Jun

    2016-12-01

    We propose a method to convert linearly polarized incident electromagnetic waves fed by a single source into multi-beam reflections with independent control of polarizations based on anisotropic metasurface at microwave frequencies. The metasurface is composed of Jerusalem Cross structures and grounded plane spaced by a dielectric substrate. By designing the reflection-phase distributions of the anisotropic metasurface along the x and y directions, the x- and y-polarized incident waves can be manipulated independently to realize multi-beam reflections. When the x- and y-polarized reflected beams are designed to the same direction with equal amplitude, the polarization state of the beam will be only controlled by the phase difference between the x- and y-polarized reflected waves. Three examples are presented to show the multi-beam reflections with flexible control of polarizations by using anisotropic metasurfaces and excellent performance. Particularly, we designed, fabricated, and measured an anisotropic metasurface for two reflected beams with one linearly polarized and the other circularly polarized. The measurement results have good agreement with the simulations in a broad bandwidth.

  11. Multi-beam reflections with flexible control of polarizations by using anisotropic metasurfaces

    PubMed Central

    Ma, Hui Feng; Liu, Yan Qing; Luan, Kang; Cui, Tie Jun

    2016-01-01

    We propose a method to convert linearly polarized incident electromagnetic waves fed by a single source into multi-beam reflections with independent control of polarizations based on anisotropic metasurface at microwave frequencies. The metasurface is composed of Jerusalem Cross structures and grounded plane spaced by a dielectric substrate. By designing the reflection-phase distributions of the anisotropic metasurface along the x and y directions, the x- and y-polarized incident waves can be manipulated independently to realize multi-beam reflections. When the x- and y-polarized reflected beams are designed to the same direction with equal amplitude, the polarization state of the beam will be only controlled by the phase difference between the x- and y-polarized reflected waves. Three examples are presented to show the multi-beam reflections with flexible control of polarizations by using anisotropic metasurfaces and excellent performance. Particularly, we designed, fabricated, and measured an anisotropic metasurface for two reflected beams with one linearly polarized and the other circularly polarized. The measurement results have good agreement with the simulations in a broad bandwidth. PMID:28000734

  12. Interaction effect of psychological distress and asthma control on productivity loss?

    PubMed

    Moullec, Grégory; FitzGerald, J Mark; Rousseau, Roxanne; Chen, Wenjia; Sadatsafavi, Mohsen

    2015-06-01

    Little is known about the potential synergistic effect of comorbid psychological distress (PD) and uncontrolled asthma (UA) on productivity loss. We estimated the productivity loss associated with the combination of these two potentially preventable conditions in employed adults with asthma. A population-based random sample of 300 adults with asthma in British Columbia, Canada, was prospectively recruited between Dec 2010 and Aug 2012. PD and productivity loss due to absenteeism and presenteeism was measured using validated instruments, and asthma control was ascertained using 2010 Global Initiative for Asthma management strategy. We used two-part regression models to study the contribution of UA and PD to productivity loss. Compared with reference group (controlled asthma (CA)+noPD), those with UA+noPD had CAD$286 (95%CI $276-297) weekly productivity loss, and those with CA+PD had CAD$465 ($445-485). Those with UA+PD had CAD$449 (437-462) in productivity loss. There was no significant interaction effect of PD with asthma control levels on productivity loss (p=0.22). In patients without PD, uncontrolled asthma was associated with a higher productivity loss than controlled asthma, but this was not the case in patients with PD. This finding can be explained by the fact that the contribution of PD to productivity loss is so large that there is no room for synergy with asthma control. Future studies should assess the impact of interventions that modify PD in patients with asthma. Copyright ©ERS 2015.

  13. Uncertainty quantification (UQ) techniques to improve predictions of laser beam control performance

    NASA Astrophysics Data System (ADS)

    Carreras, Richard A.

    2017-05-01

    Uncertainty quantification (UQ) is the study of the effects of uncertainty on the values of analytical results and the predictions of scientific models. Sources of uncertainty include imprecise knowledge of the exact values of parameters, lack of confidence in the physical models, use of imperfectly calibrated models, and irreducible uncertainties due to physical characteristics. The Air Force Research Laboratory has undertaken the challenge of understanding, developing and analyzing the techniques of UQ as they apply to Laser Beam Control. This paper proposes a simple methodology and simple results with our first attempt of applying UQ as a new analysis tool. The software toolkit which was chosen was an analytical group of algorithms from a Sandia National Laboratory (SNL) package called DAKOTA (Design Analysis Kit for Optimization and Terascale Applications). The specific application of interest to the Air Force Research Laboratory (AFRL) is the analytical prediction of the performance of a Laser Beam Control systems under various scenarios, conditions, and missions. The application of rigorous UQ techniques to the models used to predict beam control performance could greatly improve our confidence in these predictions and also improve the acceptance of advanced Laser Beam Control systems within the science and engineering communities1,2. The proposed work would follow a multi-step approach, analyzing the more easily quantified sources of uncertainty, and then including increasingly complicated physical phenomena as the work progresses. Will present the initial results, and the first steps in the incorporation of UQ into our Laser Beam Control Modeling and Simulation environments.

  14. Software-centric view on the LINC-NIRVANA beam control concept

    NASA Astrophysics Data System (ADS)

    Trowitzsch, Jan; Bertram, Thomas

    2012-09-01

    The near-infrared interferometric imaging camera for the Large Binocular Telescope, LINC-NIRVANA, is equipped with dedicated multi-conjugated adaptive optics systems and will provide an unprecedented combination of angular resolution, sensitivity, and field of view. Tight requirements resulting from long exposure interferometric imaging over a large field of view need to be fulfilled. Both incoming beams have to coincide in the focal plane of the science detector. Their pointing origins, offsets, orientations, and plate scales have to match each other and must not change during observations. Therefore, active beam control beyond fringe tracking and adaptive optics is essential. The beams need to be controlled along the complete optical path down to the combined focal plane. This paper describes the beam control aspects from a software-centric point of view. We give an outline on the overall distributed control software architecture of LINC-NIRVANA. Furthermore, we center on the beam control specific features and related functionality as foreseen and implemented in the LINC-NIRVANA software packages.

  15. Loss of Control Prevention and Recovery: Onboard Guidance, Control, and Systems Technologies

    NASA Technical Reports Server (NTRS)

    Belcastro, Christine M.

    2012-01-01

    Loss of control (LOC) is one of the largest contributors to fatal aircraft accidents worldwide. LOC accidents are complex in that they can result from numerous causal and contributing factors acting alone or (more often) in combination. These LOC hazards include vehicle impairment conditions, external disturbances; vehicle upset conditions, and inappropriate crew actions or responses. Hence, there is no single intervention strategy to prevent these accidents. NASA previously defined a comprehensive research and technology development approach for reducing LOC accidents and an associated integrated system concept. Onboard technologies for improved situation awareness, guidance, and control for LOC prevention and recovery are needed as part of this approach. Such systems should include: LOC hazards effects detection and mitigation; upset detection, prevention and recovery; and mitigation of combined hazards. NASA is conducting research in each of these areas. This paper provides an overview of this research, including the near-term LOC focus and associated analysis, as well as preliminary flight system architecture.

  16. Losses in chopper-controlled DC series motors

    NASA Technical Reports Server (NTRS)

    Hamilton, H. B.

    1982-01-01

    Motors for electric vehicle (EV) applications must have different features than dc motors designed for industrial applications. The EV motor application is characterized by the following requirements: (1) the need for highest possible efficiency from light load to overload, for maximum EV range, (2) large short time overload capability (The ratio of peak to average power varies from 5/1 in heavy city traffic to 3/1 in suburban driving situations) and (3) operation from power supply voltage levels of 84 to 144 volts (probably 120 volts maximum). A test facility utilizing a dc generator as a substitute for a battery pack was designed and utilized. Criteria for the design of such a facility are presented. Two motors, differing in design detail, commercially available for EV use were tested. Losses measured are discussed, as are waves forms and their harmonic content, the measurements of resistance and inductance, EV motor/chopper application criteria, and motor design considerations.

  17. Measurement of Absolute Excitation Cross Sections in Highly-Charged Ions Using Electron Energy Loss and Merged Beams

    NASA Astrophysics Data System (ADS)

    Chutjian, A.; Smith, Steven J.; Lozano, J. A.

    2002-11-01

    There is increasing emphasis within this decade on understanding energy balance and new phenomena observed in high electron temperature plasmas. The UV spectral return from FUSE, and the X-ray spectral return from the HETG on Chandra and the LETGS on XMM-Newton are just beginning. The line emissions are almost entirely from highly-charged ions (HCIs) of C, N, O, Ne, Mg, S, Si, Ca, and Fe. In addition, the Constellation-X mission, currently in the planning stages, will provide high-throughput X-ray spectroscopy up to photon energies of 0.12 nm (10 keV), where the primary line emitters will again be the HCIs. This array of space instruments is providing an overwhelming return of HCI spectral data from a variety of astrophysical objects. Collision strengths and Einstein A-values are required to convert the observed spectral intensities to electron temperatures and densities in the stellar plasma [1]. The JPL electron energy-loss and merged-beams approach [2] has been used to measure absolute collision strengths in a number of ions, with critical comparisons to the best available theories. Experimental methods will be reviewed, and results presented on experimental comparisons to R-Matrix and Breit-Pauli theoretical results in C3+[3], O2+[4], O5+[5], S2+[6], and Fe9+ [7]. Work is planned for comparisons in Mgq+, and higher charge states Fe(10-15)+. J. Lozano thanks the National Research Council for a fellowship though the NASA- NRC program. This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, and was supported under contract with the National Aeronautics and Space Administration.

  18. Conceptual design of hollow electron lenses for beam halo control in the Large Hadron Collider

    SciTech Connect

    Stancari, Giulio; Previtali, Valentina; Valishev, Alexander; Bruce, Roderik; Redaelli, Stefano; Rossi, Adriana; Salvachua Ferrando, Belen

    2014-06-26

    Collimation with hollow electron beams is a technique for halo control in high-power hadron beams. It is based on an electron beam (possibly pulsed or modulated in intensity) guided by strong axial magnetic fields which overlaps with the circulating beam in a short section of the ring. The concept was tested experimentally at the Fermilab Tevatron collider using a hollow electron gun installed in one of the Tevatron electron lenses. We are proposing a conceptual design for applying this technique to the Large Hadron Collider at CERN. A prototype hollow electron gun for the LHC was built and tested. The expected performance of the hollow electron beam collimator was based on Tevatron experiments and on numerical tracking simulations. Halo removal rates and enhancements of halo diffusivity were estimated as a function of beam and lattice parameters. Proton beam core lifetimes and emittance growth rates were checked to ensure that undesired effects were suppressed. Hardware specifications were based on the Tevatron devices and on preliminary engineering integration studies in the LHC machine. Required resources and a possible timeline were also outlined, together with a brief discussion of alternative halo-removal schemes and of other possible uses of electron lenses to improve the performance of the LHC.

  19. Decoupled control of a long flexible beam in orbit

    NASA Technical Reports Server (NTRS)

    Hamer, H. A.; Johnson, K. G.

    1980-01-01

    Control involved commanding changes in pitch attitude as well as nulling initial disturbances in the pitch and flexible modes. Control force requirements were analyzed. Also, the effects of parameter uncertainties on the decoupling process were analyzed and were found to be small. Two methods were investigated: the system was completely coupled and certain actuators were then eliminated, one by one, which resulted in some or all modes not fully controlled; specified modes of the system were excluded from the decoupling control law by employing viewer control actuators than modes in the model. In both methods, adjustments were made in the feedback gains to include the uncontrolled modes in the overall control of the system.

  20. Beam-based modeling and control of storage rings

    NASA Astrophysics Data System (ADS)

    Safranek, J.

    1997-05-01

    Analysis of the measured orbit response matrix is a powerful technique for debugging the linear optics of storage rings. The orbit response matrix is the change in orbit at the beam position monitors (BPMs) with changes in steering magnet excitation. Results will be presented from a computer code called LOCO (Linear Optics from Closed Orbits) that has been used to analyze the response matrices from several synchrotron light sources including the ALS, APS, NSLS VUV, NSLS X-Ray, and SRRC storage rings. The analysis accurately determines the individual quadrupole magnet gradients as well as the gains of BPMs and the calibrations of the steering magnets. The coupling terms of the response matrix such as the shift in vertical orbit from horizontal steering magnets can be included in the analysis to give the role of the quadrupoles, BPMs and steering magnets. The LOCO code can also be used to find the changes in quadrupole gradient that best compensate for gradient errors from insertion devices and sextupoles. In this way the design periodicity of the linear optics can be restored.