A Beam Transport and Loss simulation with electrostatic beam separator
NASA Astrophysics Data System (ADS)
Yang, Ming-Jen
1997-05-01
Eletrostatic beam separator (septa) string is used in the Fermilab fixed target program for slow extraction from Tevatron and for dividing the beam to different experimental area. The loss from beam interaction with the dividing wire plane of the septa is used to determine the alignment of individual septum within a string of many. The interpretation of the real life signal registered at the loss monitors is not always straight forward. A simulation is being done to model the beam split through septa string and the loss pattern at exisiting beam loss monitor locations. This should lead to a better understanding of the signal and help in the alignment operation.
Beam simulation studies of ECR beam extraction and low energy beam transport for FRIB
NASA Astrophysics Data System (ADS)
Ren, Haitao; Pozdeyev, Eduard; Lund, Steven M.; Machicoane, Guillaume; Wu, Xiaoyu; Morgan, Glenn
2016-02-01
To meet the beam power requirements of 400 kW at the fragmentation target for facility for Rare Isotope Beams (FRIB), simultaneous acceleration of two-charge states should be used for heavier ions. These intense multi-charged ion beams will be produced by a 28 GHz electron cyclotron resonance (ECR) ion source at a high voltage of 35 kV. After extraction, the ion beam will be pre-accelerated to 12 keV/u with a 50 kV platform, transported down to an achromatic charge state selection (CSS) system followed by a vertical transport line, and then injected into a radio frequency quadrupole accelerator. The TRACK code developed at ANL is used to perform the simulations of the ECR beam extraction and low energy beam transport for FRIB. In this study, we include the magnetic field of ECR ion source into simulations. Different initial beam conditions as well as different space charge neutralization levels are tested for the ECR beamline. The beam loss in CSS system and the corresponding protective measures are discussed. The detailed results about the beam dynamic simulation and beam loss in CSS system will be presented in this paper.
Beam dynamics simulations of post low energy beam transport section in RAON heavy ion accelerator
NASA Astrophysics Data System (ADS)
Jin, Hyunchang; Jang, Ji-Ho; Jang, Hyojae; Hong, In-Seok
2016-02-01
RAON (Rare isotope Accelerator Of Newness) heavy ion accelerator of the rare isotope science project in Daejeon, Korea, has been designed to accelerate multiple-charge-state beams to be used for various science programs. In the RAON accelerator, the rare isotope beams which are generated by an isotope separation on-line system with a wide range of nuclei and charges will be transported through the post Low Energy Beam Transport (LEBT) section to the Radio Frequency Quadrupole (RFQ). In order to transport many kinds of rare isotope beams stably to the RFQ, the post LEBT should be devised to satisfy the requirement of the RFQ at the end of post LEBT, simultaneously with the twiss parameters small. We will present the recent lattice design of the post LEBT in the RAON accelerator and the results of the beam dynamics simulations from it. In addition, the error analysis and correction in the post LEBT will be also described.
Prospects of ion beam extraction and transport simulations (invited)
Spaedtke, Peter; Tinschert, K.; Lang, R.; Maeder, J.; Rossbach, J.; Stetson, J. W.; Celona, L.
2008-02-15
Beam profile measurements using viewing targets and emittance measurements with pepper pot devices have established new insights about the ion beam extracted from an electron cyclotron resonance ion source (ECRIS). In our measurements we have compared two different ECRISs of CAPRICE type, one source was equipped with a standard 1.0 T hexapole magnet, whereas for the other ion source a stronger hexapole magnet with a flux density of 1.2 T has been installed. The resulting ion beam profile for each individual charge state produced by different focal strengths of an optical element can be used to estimate the emittance, but it also shows the negative influence of the hexapole on the extracted ion beam. A hexapole correction would be desirable to improve further beam transport. A possible correction scheme will be discussed. All experimental observations can be reproduced by computer simulation if a magnetic plasma is assumed. When the Larmor radius for ions becomes small, collisions are negligible for the path of ions within the plasma. Low energy electrons are highly movable along the magnetic field lines and can compensate the ion space charge within the plasma chamber.
van Goethem, M J; van der Meer, R; Reist, H W; Schippers, J M
2009-10-01
Monte Carlo simulations based on the Geant4 simulation toolkit were performed for the carbon wedge degrader used in the beam line at the Center of Proton Therapy of the Paul Scherrer Institute (PSI). The simulations are part of the beam line studies for the development and understanding of the GANTRY2 and OPTIS2 treatment facilities at PSI, but can also be applied to other beam lines. The simulated stopping power, momentum distributions at the degrader exit and beam line transmission have been compared to accurate benchmark measurements. Because the beam transport through magnetic elements is not easily modeled using Geant4a connection to the TURTLE beam line simulation program was made. After adjusting the mean ionization potential of the carbon degrader material from 78 eV to 95 eV, we found an accurate match between simulations and benchmark measurements, so that the simulation model could be validated. We found that the degrader does not completely erase the initial beam phase space even at low degraded beam energies. Using the validation results, we present a study of the usability of beryllium as a degrader material (mean ionization potential 63.7 eV). We found an improvement in the transmission of 30-45%, depending on the degraded beam energy, the higher value for the lower energies. PMID:19741273
Simulation and modeling of the Gamble II self-pinched ion beam transport experiment
Rose, D.V.; Ottinger, P.F.; Hinshelwood, D.D.
1999-07-01
Progress in numerical simulations and modeling of the self-pinched ion beam transport experiment at the Naval Research Laboratory (NRL) is reviewed. In the experiment, a 1.2-MeV, 100-kA proton beam enters a 1-m long, transport region filled with a low pressure gas (30--250 mTorr helium, or 1 Torr air). The time-dependent velocity distribution function of the injected ion beam is determined from an orbit code that uses a pinch-reflex ion diode model and the measured voltage and current from this diode on the Gamble II generator at NRL. This distribution function is used as the beam input condition for numerical simulations carried out using the hybrid particle-in-cell code IPROP. Results of the simulations will be described, and detailed comparisons will be made with various measurements, including line-integrated electron-density, proton-fluence, and beam radial-profile measurements. As observed in the experiment, the simulations show evidence of self-pinching for helium pressures between 35 and 80 mTorr. Simulations and measurements in 1 Torr air show ballistic transport. The relevance of these results to ion-driven inertial confinement fusion will be discussed.
Simulation of ion beam transport through the 400 Kv ion implanter at Michigan Ion Beam Laboratory
Naab, F. U.; Toader, O. F.; Was, G. S.
2013-04-19
The Michigan Ion Beam Laboratory houses a 400 kV ion implanter. An application that simulates the ion beam trajectories through the implanter from the ion source to the target was developed using the SIMION Registered-Sign code. The goals were to have a tool to develop an intuitive understanding of abstract physics phenomena and diagnose ion trajectories. Using this application, new implanter users of different fields in science quickly understand how the machine works and quickly learn to operate it. In this article we describe the implanter simulation application and compare the parameters of the implanter components obtained from the simulations with the measured ones. The overall agreement between the simulated and measured values of magnetic fields and electric potentials is {approx}10%.
3D particle simulation of beams using the WARP code: Transport around bends
Friedman, A.; Grote, D.P.; Callahan, D.A.; Langdon, A.B. ); Haber, I. )
1990-11-30
WARP is a discrete-particle simulation program which was developed for studies of space charge dominated ion beams. It combines features of an accelerator code and a particle-in-cell plasma simulation. The code architecture, and techniques employed to enhance efficiency, are briefly described. Current applications are reviewed. In this paper we emphasize the physics of transport of three-dimensional beams around bends. We present a simple bent-beam PIC algorithm. Using this model, we have followed a long, thin beam around a bend in a simple racetrack system (assuming straight-pipe self-fields). Results on beam dynamics are presented; no transverse emittance growth (at mid-pulse) is observed. 11 refs., 5 figs.
Erik P. Gilson; Ronald C. Davidson; Philip C. Efthimion; Richard Majeski
2004-01-29
The results presented here demonstrate that the Paul Trap Simulator Experiment (PTSX) simulates the propagation of intense charged particle beams over distances of many kilometers through magnetic alternating-gradient (AG) transport systems by making use of the similarity between the transverse dynamics of particles in the two systems. Plasmas have been trapped that correspond to normalized intensity parameters s = wp2 (0)/2wq2 * 0.8, where wp(r) is the plasmas frequency and wq is the average transverse focusing frequency in the smooth-focusing approximation. The measured root-mean-squared (RMS) radius of the beam is consistent with a model, equally applicable to both PTSX and AG systems that balances the average inward confining force against the outward pressure-gradient and space-charge forces. The PTSX device confines one-component cesium ion plasmas for hundreds of milliseconds, which is equivalent to over 10 km of beam propagation.
PATH: a lumped-element beam-transport simulation program with space charge
Farrell, J.A.
1983-01-01
PATH is a group of computer programs for simulating charged-particle beam-transport systems. It was developed for evaluating the effects of some aberrations without a time-consuming integration of trajectories through the system. The beam-transport portion of PATH is derived from the well-known program, DECAY TURTLE. PATH contains all features available in DECAY TURTLE (including the input format) plus additional features such as a more flexible random-ray generator, longitudinal phase space, some additional beamline elements, and space-charge routines. One of the programs also provides a simulation of an Alvarez linear accelerator. The programs, originally written for a CDC 7600 computer system, also are available on a VAX-VMS system. All of the programs are interactive with input prompting for ease of use.
Patel, A.; Wills, J. S. C.; Diamond, W. T.
2008-04-15
Ion beam extraction from two different ion sources with single aperture triode extraction columns was simulated with the particle beam transport codes PBGUNS and IGUN. For each ion source, the simulation results are compared to experimental data generated on well-equipped test stands. Both codes reproduced the qualitative behavior of the extracted ion beams to incremental and scaled changes to the extraction electrode geometry observed on the test stands. Numerical values of optimum beam currents and beam emittance generated by the simulations also agree well with test stand data.
NASA Astrophysics Data System (ADS)
Grishkov, A. A.; Kornilov, S. Yu.; Rempe, N. G.; Shidlovskiy, S. V.; Shklyaev, V. A.
2016-07-01
The results of computer simulations of the electron-optical system of an electron gun with a plasma emitter are presented. The simulations are performed using the KOBRA3-INP, XOOPIC, and ANSYS codes. The results describe the electron beam formation and transport. The electron trajectories are analyzed. The mechanisms of gas influence on the energy inhomogeneity of the beam and its current in the regions of beam primary formation, acceleration, and transport are described. Recommendations for optimizing the electron-optical system with a plasma emitter are presented.
NASA Astrophysics Data System (ADS)
Tyson, J. A.; Sasian, J.; Gilmore, K.; Bradshaw, A.; Claver, C.; Klint, M.; Muller, G.; Poczulp, G.; Resseguie, E.
2014-07-01
We describe a camera beam simulator for the LSST which is capable of illuminating a 60mm field at f/1.2 with realistic astronomical scenes, enabling studies of CCD astrometric and photometric performance. The goal is to fully simulate LSST observing, in order to characterize charge transport and other features in the thick fully-depleted CCDs and to probe low level systematics under realistic conditions. The automated system simulates the centrally obscured LSST beam and sky scenes, including the spectral shape of the night sky. The doubly telecentric design uses a nearly unit magnification design consisting of a spherical mirror, three BK7 lenses, and one beam-splitter window. To achieve the relatively large field the beam-splitter window is used twice. The motivation for this LSST beam test facility was driven by the need to fully characterize a new generation of thick fully-depleted CCDs, and assess their suitability for the broad range of science which is planned for LSST. Due to the fast beam illumination and the thick silicon design [each pixel is 10 microns wide and over 100 microns deep] at long wavelengths there can be effects of photon transport and charge transport in the high purity silicon. The focal surface covers a field more than sufficient for a 40×40mm LSST CCD. Delivered optical quality meets design goals, with 50% energy within a 5 micron circle. The tests of CCD performance are briefly described.
Simulation of the generation and long distance transport of proton beams at LULI
NASA Astrophysics Data System (ADS)
Welch, Dale; Cuneo, Michael; Campbell, Robert; Mehlhorn, Thomas
2004-11-01
High current, energetic protons are produced by irradiating thin metal foils with intense lasers[1]. At LULI[2], the current and energy of these protons as well as that of their accompanying electron cloud have been measured using magnetized and filtered Faraday cups. Here, the laser plasma interaction produced relativistic electrons at the critical surface. These electrons were transported through a 10-μm Au foil and created a space charge cloud that accelerates protons contaminants on the back side. The energetic protons and electrons drift several centimeters before reaching the Faraday cup. Self-consistent electromagnetic simulations of this process using a hybrid code are presented with comparisons to data. The neutralization of the high quality proton beam by the electron cloud is then studied. 1. R. Snavely et al., Phys. Rev. Lett. 85, 2945 (2000). 2. M. Hegelich et al., Phys. Rev. Lett. 89, 085002 (2002).
Comparison of beam transport simulations to measurements at the Los Alamos Proton Storage Ring
Wilkinson, C.; Neri, F.; Fitzgerald, D.H.; Blind, B.; Macek, R.; Plum, M.; Sander, O.; Thiessen, H.A.
1997-10-01
The ability to model and simulate beam behavior in the Proton Storage Ring (PSR) of the Los Alamos Neutron Science Center (LANSCE) is an important diagnostic and predictive tool. This paper gives the results of an effort to model the ring apertures and lattice and use beam simulation programs to track the beam. The results are then compared to measured activation levels from beam loss in the ring. The success of the method determines its usefulness in evaluating the effects of planned upgrades to the Proton Storage Ring.
A 3D Model for Ion Beam Formation and Transport Simulation
Qiang, J.; Todd, D.; Leitner, D.
2006-02-07
In this paper, we present a three-dimensional model forself-consistently modeling ion beam formation from plasma ion sources andtransporting in low energy beam transport systems. A multi-sectionoverlapped computational domain has been used to break the originaltransport system into a number of weakly coupled subsystems. Within eachsubsystem, macro-particle tracking is used to obtain the charge densitydistribution in this subdomain. The three-dimensional Poisson equation issolved within the subdomain after each particle tracking to obtain theself-consistent space-charge forces and the particle tracking is repeateduntil the solution converges. Two new Poisson solvers based on acombination of the spectral method and the finite difference multigridmethod have been developed to solve the Poisson equation in cylindricalcoordinates for the straight beam transport section and in Frenet-Serretcoordinates for the bending magnet section. This model can have importantapplication in design and optimization of the low energy beam line opticsof the proposed Rare Isotope Accelerator (RIA) front end.
Thoma, C.; Welch, D.R.; Yu, S.S.; Henestroza, E.; Roy, P.K.; Eylon, S.; Gilson, E.P.
2004-09-22
The Neutralized Transport Experiment (NTX) at Lawrence Berkeley National Laboratory has been designed to study the final focus and neutralization of high perveance ion beams for applications in heavy ion fusion (HIF) and high energy density physics (HEDP) experiments. Pre-formed plasmas in the last meter before the target of the scaled experiment provide a source of electrons which neutralize the ion current and prevent the space-charge induced spreading of the beam spot. NTX physics issues are discussed and experimental data is analyzed and compared with 3D particle-in-cell simulations. Along with detailed target images, 4D phase-space data of the NTX at the entrance of the neutralization region has been acquired. This data is used to provide a more accurate beam distribution with which to initialize the simulation. Previous treatments have used various idealized beam distributions which lack the detailed features of the experimental ion beam images. Simulation results are compared with NTX experimental measurements for 250 keV K{sup +} ion beams with dimensionless perveance of 1-7 x 10{sup -4}. In both simulation and experiment, the deduced beam charge neutralization is close to the predicted maximum value.
Le Guennec, Yves; Savin, Éric
2011-12-01
The theory of microlocal analysis shows that the energy density associated with the high-frequency vibrations of a three-dimensional Timoshenko beam satisfies a Liouville-type transport equation. In the present application, the material of the beam is assumed to be isotropic. Its parameters are allowed to vary along the beam axis at length scales much larger than the wavelength of the high-frequency waves traveling in it. Moreover, the curvature and torsion of the beam are accounted for. The first part of the paper focuses on the derivation of the transport model for a single three-dimensional beam. In order to extend this model to beam trusses, the reflection/transmission phenomena of the energy fluxes at junctions of beams are described by power flow reflection/transmission operators in a subsequent part. For numerical simulations, a discontinuous Galerkin finite element method is used on account of the discontinuities of the energy density field at the junctions. Thus, a complete mechanical-numerical modeling of the linear transient dynamics of beam trusses is proposed. It is illustrated by numerical examples highlighting some remarkable features of high-frequency vibrations: The onset of a diffusive regime characterized by energy equipartition rules at late times. Energy diffusion is prompted by the multiple reflection/transmission of waves at the junctions, with possible mode (polarization) conversions. This is the regime applicable to the statistical energy analysis of structural acoustics systems. The main purpose of this research is to develop an effective strategy to simulate and predict the transient response of beam trusses impacted by acoustic or mechanical shocks. PMID:22225027
Simulation of charged-particle beam transport in a gas using a hybrid particle-fluid plasma model
NASA Astrophysics Data System (ADS)
Welch, D. R.; Olson, C. L.; Sanford, T. W. L.
1994-03-01
The simulation of charged-particle beam transport in a ˜1 Torr gas requires accurate plasma-electron modeling. A simple resistive model, which assumes local energy deposition and a thermal plasma-electron distribution, is inadequate. A hybrid model has been implemented into the particle-in-cell simulation code, iprop (The iprop Three-Dimensional Beam Propagation Code, AMRC-R-966, available from D. Welch, Mission Research Corporation, 1720 Randolph Road SE, Albuquerque, NM 87106, September 1987), in which plasma electrons are divided into high-energy macroparticle and thermal-fluid components. This model, which includes ``knock-on'' bound-electron collision and runaway sources for high-energy electrons, is then used in the simulation of relativistic electron-beam and ion-beam experiments. Results are found to be in agreement with HERMES III [Performance of the HERMES III Gamma Ray Simulator, in Digest of Technical Papers, 7th IEEE Pulsed Power Conference, Monterey, CA, 11 June 1989 (Institute of Electrical and Electronic Engineers, New York, 1989), pp. 26-31] and GAMBLE II [Phys. Rev. Lett. 70, 2573 (1993)] experimental observables.
The GEANT4 toolkit capability in the hadron therapy field: simulation of a transport beam line
NASA Astrophysics Data System (ADS)
Cirrone, G. A. P.; Cuttone, G.; Di Rosa, F.; Raffaele, L.; Russo, G.; Guatelli, S.; Pia, M. G.
2006-01-01
At Laboratori Nazionali del Sud of the Instituto Nazionale di Fisica Nucleare of Catania (Sicily, Italy), the first Italian hadron therapy facility named CATANA (Centro di AdroTerapia ed Applicazioni Nucleari Avanzate) has been realized. Inside CATANA 62 MeV proton beams, accelerated by a superconducting cyclotron, are used for the radiotherapeutic treatments of some types of ocular tumours. Therapy with hadron beams still represents a pioneer technique, and only a few centers worldwide can provide this advanced specialized cancer treatment. On the basis of the experience so far gained, and considering the future hadron-therapy facilities to be developed (Rinecker, Munich Germany, Heidelberg/GSI, Darmstadt, Germany, PSI Villigen, Switzerland, CNAO, Pavia, Italy, Centro di Adroterapia, Catania, Italy) we decided to develop a Monte Carlo application based on the GEANT4 toolkit, for the design, the realization and the optimization of a proton-therapy beam line. Another feature of our project is to provide a general tool able to study the interactions of hadrons with the human tissue and to test the analytical-based treatment planning systems actually used in the routine practice. All the typical elements of a hadron-therapy line, such as diffusers, range shifters, collimators and detectors were modelled. In particular, we simulated the Markus type ionization chamber and a Gaf Chromic film as dosimeters to reconstruct the depth (Bragg peak and Spread Out Bragg Peak) and lateral dose distributions, respectively. We validated our simulated detectors comparing the results with the experimental data available in our facility.
INJECTOR PARTICLE SIMULATION AND BEAM TRANSPORT IN A COMPACT LINEAR PROTON ACCELERATOR
Blackfield, D T; Chen, Y J; Harris, J; Nelson, S; Paul, A; Poole, B
2007-06-18
A compact Dielectric Wall Accelerator (DWA), with field gradient up to 100 MW/m is being developed to accelerate proton bunches for use in cancer therapy treatment. The injector must create a proton pulse up to several hundred picoseconds, which is then shaped and accelerated with energies up to 250 MeV. The Particle-In-Cell (PIC) code LSP is used to model several aspects of this design. First, we use LSP to obtain the voltage waveform in the A-K gap that will produce a proton bunch with the requisite charge. We then model pulse compression and shaping in the section between the A-K gap and the DWA. We finally use LSP to model the beam transport through the DWA.
Tenenbaum, P.; /SLAC
2005-09-30
We report on Lucretia, a new simulation tool for the study of single-pass electron beam transport systems. Lucretia supports a combination of analytic and tracking techniques to model the tuning and operation of bunch compressors, linear accelerators, and beam delivery systems of linear colliders and linac-driven Free Electron Laser (FEL) facilities. Extensive use of Matlab scripting, graphics, and numerical capabilities maximize the flexibility of the system, and emphasis has been placed on representing and preserving the fixed relationships between elements (common girders, power supplies, etc.) which must be respected in the design of tuning algorithms. An overview of the code organization, some simple examples, and plans for future development are discussed.
Qiang, J.; Leitner, D.; Todd, D.S.; Ryne, R.D.
2005-03-15
The superconducting ECR ion source VENUS serves as the prototype injector ion source for the Rare Isotope Accelerator (RIA) driver linac. The RIA driver linac requires a great variety of high charge state ion beams with up to an order of magnitude higher intensity than currently achievable with conventional ECR ion sources. In order to design the beam line optics of the low energy beam line for the RIA front end for the wide parameter range required for the RIA driver accelerator, reliable simulations of the ion beam extraction from the ECR ion source through the ion mass analyzing system are essential. The RIA low energy beam transport line must be able to transport intense beams (up to 10 mA) of light and heavy ions at 30 keV.For this purpose, LBNL is developing the parallel 3D particle-in-cell code IMPACT to simulate the ion beam transport from the ECR extraction aperture through the analyzing section of the low energy transport system. IMPACT, a parallel, particle-in-cell code, is currently used to model the superconducting RF linac section of RIA and is being modified in order to simulate DC beams from the ECR ion source extraction. By using the high performance of parallel supercomputing we will be able to account consistently for the changing space charge in the extraction region and the analyzing section. A progress report and early results in the modeling of the VENUS source will be presented.
NASA Astrophysics Data System (ADS)
Qiang, J.; Leitner, D.; Todd, D. S.; Ryne, R. D.
2005-03-01
The superconducting ECR ion source VENUS serves as the prototype injector ion source for the Rare Isotope Accelerator (RIA) driver linac. The RIA driver linac requires a great variety of high charge state ion beams with up to an order of magnitude higher intensity than currently achievable with conventional ECR ion sources. In order to design the beam line optics of the low energy beam line for the RIA front end for the wide parameter range required for the RIA driver accelerator, reliable simulations of the ion beam extraction from the ECR ion source through the ion mass analyzing system are essential. The RIA low energy beam transport line must be able to transport intense beams (up to 10 mA) of light and heavy ions at 30 keV. For this purpose, LBNL is developing the parallel 3D particle-in-cell code IMPACT to simulate the ion beam transport from the ECR extraction aperture through the analyzing section of the low energy transport system. IMPACT, a parallel, particle-in-cell code, is currently used to model the superconducting RF linac section of RIA and is being modified in order to simulate DC beams from the ECR ion source extraction. By using the high performance of parallel supercomputing we will be able to account consistently for the changing space charge in the extraction region and the analyzing section. A progress report and early results in the modeling of the VENUS source will be presented.
2005-11-08
IBSimu(Ion Beam Simulator) is a computer program for making two and three dimensional ion optical simulations. The program can solve electrostatic field in a rectangular mesh using Poisson equation using Finite Difference method (FDM). The mesh can consist of a coarse and a fine part so that the calculation accuracy can be increased in critical areas of the geometry, while most of the calculation is done quickly using the coarse mesh. IBSimu can launch ionmore » beam trajectories into the simulation from an injection surface or fomo plasma. Ion beam space charge of time independent simulations can be taken in account using Viasov iteration. Plasma is calculated by compensating space charge with electrons having Boltzmann energy distribution. The simulation software can also be used to calculate time dependent cases if the space charge is not calculated. Software includes diagnostic tools for plotting the geometry, electric field, space charge map, ion beam trajectories, emittance data and beam profiles.« less
Straight low energy beam transport for intense uranium beams
NASA Astrophysics Data System (ADS)
Xiao, C.; Groening, L.; Vormann, H.; Mickat, S.; Hollinger, R.; Adonin, A.; Orzhekhovskaya, A.; Maier, M.; Al-Omari, H.; Barth, W.; Kester, O. K.; Yaramyshev, S.
2015-07-01
A new high current uranium ion source and dedicated Low Energy Beam Transport (LEBT) will be built at the GSI High Current Injector (HSI). This LEBT will be integrated into the existing complex which already comprises two branches. The paper presents the design and dynamics simulation using the TRACE-3D and TRACK code. The simulation results illustrate that this straight LEBT can transport uranium beams over a wide range of space-charge compensation, and can provide 15.4 (14.2) mA U4+ inside of the effective acceptance of the subsequent RFQ assuming the space-charge is compensated to 100% (95%).
3-D simulations of multiple beam klystrons
Smithe, David N.; Bettenhausen, Mike; Ludeking, Larry; Caryotakis, G.; Sprehn, Daryl; Scheitrum, Glenn
1999-05-07
The MAGIC3D simulation code is being used to assess the multi-dimensional physics issues relating to the design and operation of multiple beam klystrons. Investigations, to date, include a detailed study of the mode structure of the cavities in the 19-beam hexagonally packed geometry and a study of the velocity spread caused by the cavity mode's field profile. Some attempts to minimize this effect are investigated. Additional simulations have provided quantification of the beam loading Q in a dual input cavity, and optimization of a dual output cavity. An important goal of the simulations is an accurate picture of beam transport along the length of the MBK. We have quantified the magnitude and spatial variation of the beam-line space charge interactions within a cavity gap. Present simulations have demonstrated the transport of the beam through three cavities (the present limits of our simulation size) without difficulty; additional length simulations are expected. We have also examined unbalanced beam-line scenarios, e.g., one beam-line suppressed, and find little disturbance to the transport in individual cavity tests, with results for multiple cavity transport expected.
NASA Astrophysics Data System (ADS)
Kim, J.; Qiao, B.; McGuffey, C.; Wei, M. S.; Grabowski, P. E.; Beg, F. N.
2015-07-01
The first self-consistent hybrid particle-in-cell (PIC) simulation of intense proton beam transport and energy deposition in solid-density matter is presented. Both the individual proton slowing-down and the collective beam-plasma interaction effects are taken into account with a new dynamic proton stopping power module that has been added to a hybrid PIC code. In this module, the target local stopping power can be updated at each time step based on its thermodynamic state. For intense proton beams, the reduction of target stopping power from the cold condition due to continuous proton heating eventually leads to broadening of the particle range and energy deposition far beyond the Bragg peak. For tightly focused beams, large magnetic field growth in collective interactions results in self-focusing of the beam and much stronger localized heating of the target.
NASA Astrophysics Data System (ADS)
Nishiuchi, M.; Sakaki, H.; Hori, T.; Bolton, P. R.; Ogura, K.; Sagisaka, A.; Yogo, A.; Mori, M.; Orimo, S.; Pirozhkov, A. S.; Daito, I.; Kiriyama, H.; Okada, H.; Kanazawa, S.; Kondo, S.; Shimomura, T.; Tanoue, M.; Nakai, Y.; Sasao, H.; Wakai, D.; Daido, H.; Kondo, K.; Souda, H.; Tongu, H.; Noda, A.; Iseki, Y.; Nagafuchi, T.; Maeda, K.; Hanawa, K.; Yoshiyuki, T.; Shirai, T.
2010-07-01
A laser-driven repetition-rated 1.9 MeV proton beam line composed of permanent quadrupole magnets (PMQs), a radio frequency (rf) phase rotation cavity, and a tunable monochromator is developed to evaluate and to test the simulation of laser-accelerated proton beam transport through an integrated system for the first time. In addition, the proton spectral modulation and focusing behavior of the rf phase rotation cavity device is monitored with input from a PMQ triplet. In the 1.9 MeV region we observe very weak proton defocusing by the phase rotation cavity. The final transmitted bunch duration and transverse profile are well predicted by the PARMILA particle transport code. The transmitted proton beam duration of 6 ns corresponds to an energy spread near 5% for which the transport efficiency is simulated to be 10%. The predictive capability of PARMILA suggests that it can be useful in the design of future higher energy transport beam lines as part of an integrated laser-driven ion accelerator system.
Conditioner for a helically transported electron beam
Wang, Changbiao.
1992-05-01
The kinetic theory is developed to investigate a conditioner for a helically transported electron beam. Linear expressions for axial velocity spread are derived. Numerical simulation is used to check the theoretical results and examine nonlinear aspects of the conditioning process. The results show that in the linear regime the action of the beam conditioner on a pulsed beam mainly depends on the phase at which the beam enters the conditioner and depends only slightly on the operating wavelength. In the nonlinear regime, however, the action of the conditioner strongly depends on the operating wavelength and only slightly upon the entrance phase. For a properly chosen operating wavelength, a little less than the electron's relativistic cyclotron wavelength, the conditioner can decrease the axial velocity spread of a pulsed beam down to less than one-third of its initial value.
Conditioner for a helically transported electron beam
Wang, Changbiao
1992-05-01
The kinetic theory is developed to investigate a conditioner for a helically transported electron beam. Linear expressions for axial velocity spread are derived. Numerical simulation is used to check the theoretical results and examine nonlinear aspects of the conditioning process. The results show that in the linear regime the action of the beam conditioner on a pulsed beam mainly depends on the phase at which the beam enters the conditioner and depends only slightly on the operating wavelength. In the nonlinear regime, however, the action of the conditioner strongly depends on the operating wavelength and only slightly upon the entrance phase. For a properly chosen operating wavelength, a little less than the electron`s relativistic cyclotron wavelength, the conditioner can decrease the axial velocity spread of a pulsed beam down to less than one-third of its initial value.
H{sup -} beam transport experiments in a solenoid low energy beam transport
Gabor, C.; Back, J. J.; Faircloth, D. C.; Lawrie, S. R.; Letchford, A. P.; Izaola, Z.
2012-02-15
The Front End Test Stand (FETS) is located at Rutherford Appleton Laboratory and aims for a high current, fast chopped 3 MeV H{sup -} ion beam suitable for future high power proton accelerators like ISIS upgrade. The main components of the front end are the Penning ion source, a low energy beam transport line, an radio-frequency quadrupole (RFQ) and a medium energy beam transport (MEBT) providing also a chopper section and rebuncher. FETS is in the stage of commissioning its low energy beam transport (LEBT) line consisting of three solenoids. The LEBT has to transport an H{sup -} high current beam (up to 60 mA) at 65 keV. This is the injection energy of the beam into the RFQ. The main diagnostics are slit-slit emittance scanners for each transversal plane. For optimizing the matching to the RFQ, experiments have been performed with a variety of solenoid settings to better understand the actual beam transport. Occasionally, source parameters such as extractor slit width and beam energy were varied as well. The paper also discusses simulations based on these measurements.
Overview of the APT High-Energy Beam Transport and Beam Expanders
NASA Astrophysics Data System (ADS)
Shafer, R. E.; Blind, B.; Gray, E. R.; Gilpatrick, J. D.; Barlow, D.; Lawrence, G. P.
1997-05-01
The APT high energy beam transport (HEBT) and beam expanders transport the 1700-MeV, 100-mA cw proton beam from the linac to any of three end stations. The HEBT includes extensive beam diagnostics, collimators, and dejitter correction, to monitor and control the 170-MW proton beam prior to expansion. One zero-degree beam line and two achromatic bends transport the beam to one of three beam expanders. These nonlinear beam expanders, making use of higher order multipole magnets and dithering dipoles, expand the beam to a uniform density, 16-cm wide by 160-cm high rectangular profile on the tritium-production targets. The overall optics design will be reviewed, and beam simulations will be presented.
Molecular Ion Beam Transportation for Low Energy Ion Implantation
Kulevoy, T. V.; Kropachev, G. N.; Seleznev, D. N.; Yakushin, P. E.; Kuibeda, R. P.; Kozlov, A. V.; Koshelev, V. A.; Hershcovitch, A.; Johnson, B. M.; Gushenets, V. I.; Oks, E. M.; Polozov, S. M.; Poole, H. J.
2011-01-07
A joint research and development of steady state intense boron ion sources for 100's of electron-volt ion implanters has been in progress for the past five years. Current density limitation associated with extracting and transporting low energy ion beams result in lower beam currents that in turn adversely affects the process throughput. The transport channel with electrostatic lenses for decaborane (B{sub 10}H{sub 14}) and carborane (C{sub 2}B{sub 10}H{sub 12}) ion beams transportation was developed and investigated. The significant increase of ion beam intensity at the beam transport channel output is demonstrated. The transport channel simulation, construction and experimental results of ion beam transportation are presented.
IMPACT simulation and the SNS linac beam
Zhang, Y.; Qiang, J.
2008-09-03
Multi-particle tracking simulations for the SNS linac beam dynamics studies are performed with the IMPACT code. Beam measurement results are compared with the computer simulations, including beam longitudinal halo and beam losses in the superconducting linac, transverse beam Courant-Snyder parameters and the longitudinal beam emittance in the linac. In most cases, the simulations show good agreement with the measured results.
Overview of the APT high-energy beam transport and beam expanders
Shafer, R.E.; Blind, B.; Gray, E.R.
1997-08-01
The APT high energy beam transport (HEBT) and beam expanders convey the 1700-MeV, 100-mA cw proton beam from the linac to the tritium target/blanket assembly, or a tuning beam stop. The HEBT includes extensive beam diagnostics, collimators, and beam jitter correction, to monitor and control the 170-MW beam prior to expansion. A zero-degree beamline conveys the beam to the beam stop, and an achromatic bend conveys the beam to the tritium production target. Nonlinear beam expanders make use of higher-order multipole magnets and dithering dipoles to expand the beam to a uniform-density, 16-cm wide by 160-cm high rectangular profile on the tritium-production target. The overall optics design will be reviewed, and beam simulations will be presented.
NASA Astrophysics Data System (ADS)
Bartesaghi, G.; Gambarini, G.; Negri, A.; Carrara, M.; Burian, J.; Viererbl, L.
2010-04-01
Presently there are no standard protocols for dosimetry in neutron beams for boron neutron capture therapy (BNCT) treatments. Because of the high radiation intensity and of the presence at the same time of radiation components having different linear energy transfer and therefore different biological weighting factors, treatment planning in epithermal neutron fields for BNCT is usually performed by means of Monte Carlo calculations; experimental measurements are required in order to characterize the neutron source and to validate the treatment planning. In this work Monte Carlo simulations in two kinds of tissue-equivalent phantoms are described. The neutron transport has been studied, together with the distribution of the boron dose; simulation results are compared with data taken with Fricke gel dosimeters in form of layers, showing a good agreement.
Simulation of integrated beam experiment designs
Grote, D.P.; Sharp, W.M.
2004-06-11
Simulation of designs of an Integrated Beam Experiment (IBX) class accelerator have been carried out. These simulations are an important tool for validating such designs. Issues such as envelope mismatch and emittance growth can be examined in a self-consistent manner, including the details of injection, accelerator transitions, long-term transport, and longitudinal compression. The simulations are three-dimensional and time-dependent, and begin at the source. They continue up through the end of the acceleration region, at which point the data is passed on to a separate simulation of the drift compression. Results are be presented.
Transport of electron beams with initial transverse-longitudinal correlation
NASA Astrophysics Data System (ADS)
Harris, J. R.; Lewellen, J. W.; Poole, B. R.
2013-08-01
When an electron beam whose current varies in time is extracted from a DC gun, the competition between the time-dependent space charge force and the time-independent focusing force will cause a correlation between radius, divergence, current, and position along the beam. This correlation will determine the beam's configuration in trace space, and together with the design of the downstream transport system, will determine the quality of the transport solutions that can be obtained, including the amplitude of the mismatch oscillations occurring in each slice of the beam. Recent simulations of a simplified diode with Pierce-type focusing operating at nonrelativistic voltages indicated that the radius and divergence of beams extracted from such guns can be approximated to high accuracy as linear functions of current. Here, we consider the impact of this dependence on the beam configuration in trace space and investigate the implications for matching and transport of such correlated beams in uniform linear focusing channels.
Transportation Anslysis Simulation System
2004-08-23
TRANSIMS version 3.1 is an integrated set of analytical and simulation models and supporting databases. The system is designed to create a virtual metropolitan region with representation of each of the regions individuals, their activities and the transportation infrastructure they use. TRANSIMS puts into practice a new, disaggregate approach to travel demand modeling using agent-based micro-simulation technology. TRANSIMS methodology creates a virtual metropolitan region with representation of the transportation infrastructure and the population, at the level of households and individual travelers. Trips a planned to satisfy the populations activity pattems at the individual traveler level. TRANSIMS then simulates the movement of travelers and vehicles across the transportation network using multiple modes, including car, transit, bike and walk, on a second-by-second basis. Metropolitan planners must plan growth of their cities according to the stringent transportation system planning requirements of the Interniodal Surface Transportation Efficiency Act of 1991, the Clean Air Act Amendments of 1990 and other similar laws and regulations. These require each state and its metropotitan regions to work together to develop short and long term transportation improvement plans. The plans must (1) estimate the future transportation needs for travelers and goods movements, (2) evaluate ways to manage and reduce congestion, (3) examine the effectiveness of building new roads and transit systems, and (4) limit the environmental impact of the various strategies. The needed consistent and accurate transportation improvement plans require an analytical capability that properly accounts for travel demand, human behavior, traffic and transit operations, major investments, and environmental effects. Other existing planning tools use aggregated information and representative behavior to predict average response and average use of transportation facilities. They do not account
Transportation Anslysis Simulation System
2004-08-23
TRANSIMS version 3.1 is an integrated set of analytical and simulation models and supporting databases. The system is designed to create a virtual metropolitan region with representation of each of the regions individuals, their activities and the transportation infrastructure they use. TRANSIMS puts into practice a new, disaggregate approach to travel demand modeling using agent-based micro-simulation technology. TRANSIMS methodology creates a virtual metropolitan region with representation of the transportation infrastructure and the population, at themore » level of households and individual travelers. Trips a planned to satisfy the populations activity pattems at the individual traveler level. TRANSIMS then simulates the movement of travelers and vehicles across the transportation network using multiple modes, including car, transit, bike and walk, on a second-by-second basis. Metropolitan planners must plan growth of their cities according to the stringent transportation system planning requirements of the Interniodal Surface Transportation Efficiency Act of 1991, the Clean Air Act Amendments of 1990 and other similar laws and regulations. These require each state and its metropotitan regions to work together to develop short and long term transportation improvement plans. The plans must (1) estimate the future transportation needs for travelers and goods movements, (2) evaluate ways to manage and reduce congestion, (3) examine the effectiveness of building new roads and transit systems, and (4) limit the environmental impact of the various strategies. The needed consistent and accurate transportation improvement plans require an analytical capability that properly accounts for travel demand, human behavior, traffic and transit operations, major investments, and environmental effects. Other existing planning tools use aggregated information and representative behavior to predict average response and average use of transportation facilities. They do not
Los Alamos beam halo experiment: comparing theory, simulation and experiment.
Wangler, Thomas P.,; Qiang, J.
2002-01-01
We compare macroparticle simulations with measurements from a proton beam-halo experiment in a 52-quadrupole periodic-focusing channel. Three different initial distributions with the same Courant-Snyder parameters and emittances, but different shapes, predict different beam profiles in the transport system. Input distributions with greater population in the tails produce larger rates of emittance growth, a result that is qualitatively consistent with the particle-core model of halo formation in mismatched beams. The simulations underestimate the growth rate of halo and emittance for mismatched beams. Better agreement between simulations and experiment may require an input distribution that represents more accurately the tails of the real input beam.
Low energy beam transport system developments
NASA Astrophysics Data System (ADS)
Dudnikov, V.; Han, B.; Stockli, M.; Welton, R.; Dudnikova, G.
2015-04-01
For high brightness beam production it is important to preserve the brightness in the low energy beam transport system (LEBT) used to transport and match the ion beams to the next stage of acceleration, usually an RFQ. While electrostatic focusing can be problematic for high current beam transport, reliable electrostatic LEBT operation has been demonstrated with H- beams up to 60 mA. Now, however, it is commonly accepted that an optimal LEBT for high current accelerator applications consists of focusing solenoids with space charge compensation. Two-solenoid LEBTs are successfully used for high current (>100 mA) proton beam transport. Preservation of low emittances (~0.15 π mm-mrad) requires the addition of a heavy gas (Xe, Kr), which causes ~5% of proton loss in a 1 m long LEBT. Similar Xe densities would be required to preserve low emittances of H- beams, but such gas densities cause unacceptably high H- beam losses. A short LEBT with only one short solenoid, movable for RFQ matching, can be used for reduced negative ion stripping. A strong electrostatic-focusing LEBT has been successfully adopted for transport of high current H- beams in the SNS Front End. Some modifications of such electrostatic LEBTs are expected to improve the reliable transport of intense positive and negative ion beams without greatly degrading their low emittances. We concentrate on processes that determine the beam brightness degradation and on their prevention. Proposed improvements to the SNS electrostatic LEBT are discussed.
Transport of 3D space charge dominated beams
NASA Astrophysics Data System (ADS)
Lü, Jian-Qin
2013-10-01
In this paper we present the theoretical analysis and the computer code design for the intense pulsed beam transport. Intense beam dynamics is a very important issue in low-energy high-current accelerators and beam transport systems. This problem affects beam transmission and beam qualities. Therefore, it attracts the attention of the accelerator physicists worldwide. The analysis and calculation for the intense beam dynamics are very complicated, because the state of particle motion is dominated not only by the applied electromagnetic fields, but also by the beam-induced electromagnetic fields (self-fields). Moreover, the self fields are related to the beam dimensions and particle distributions. So, it is very difficult to get the self-consistent solutions of particle motion analytically. For this reason, we combine the Lie algebraic method and the particle in cell (PIC) scheme together to simulate intense 3D beam transport. With the Lie algebraic method we analyze the particle nonlinear trajectories in the applied electromagnetic fields up to third order approximation, and with the PIC algorithm we calculate the space charge effects to the particle motion. Based on the theoretical analysis, we have developed a computer code, which calculates beam transport systems consisting of electrostatic lenses, electrostatic accelerating columns, solenoid lenses, magnetic and electric quadruples, magnetic sextupoles, octopuses and different kinds of electromagnetic analyzers. The optimization calculations and the graphic display for the calculated results are provided by the code.
Beam-transport study of an isocentric rotating ion gantry with minimum number of quadrupoles
NASA Astrophysics Data System (ADS)
Pavlovic, Márius; Griesmayer, Erich; Seemann, Rolf
2005-06-01
A beam-transport study of an isocentric gantry for ion therapy is presented. The gantry is designed with the number of quadrupoles down to the theoretical minimum, which is the feature published for the first time in this paper. This feature has been achieved without compromising the ion-optical functions of the beam-transport system that is capable of handling non-symmetric beams (beams with different emittances in vertical and horizontal plane), pencil-beam scanning, double-achromatic optics and beam-size control. Ion-optical properties of the beam-transport system are described, discussed and illustrated by computer simulations performed by the TRANSPORT-code.
GPU-optimized Code for Long-term Simulations of Beam-beam Effects in Colliders
Roblin, Yves; Morozov, Vasiliy; Terzic, Balsa; Aturban, Mohamed A.; Ranjan, D.; Zubair, Mohammed
2013-06-01
We report on the development of the new code for long-term simulation of beam-beam effects in particle colliders. The underlying physical model relies on a matrix-based arbitrary-order symplectic particle tracking for beam transport and the Bassetti-Erskine approximation for beam-beam interaction. The computations are accelerated through a parallel implementation on a hybrid GPU/CPU platform. With the new code, a previously computationally prohibitive long-term simulations become tractable. We use the new code to model the proposed medium-energy electron-ion collider (MEIC) at Jefferson Lab.
DARHT-II Downstream Beam Transport Beamline
Westenskow, G A; Bertolini, L R; Duffy, P T; Paul, A C
2000-08-01
This paper describes the mechanical design of the downstream beam transport line for the second axis of the Dual Axis Radiographic Hydrodynamic Test (DARHT II) Facility. The DARHT-II project is a collaboration between LANL, LBNL and LLNL. DARHT II is a 20-MeV, 2000-Amperes, 2-{micro}sec linear induction accelerator designed to generate short bursts of x-rays for the purpose of radiographing dense objects. The downstream beam transport line is approximately 20-meter long region extending from the end of the accelerator to the bremsstrahlung target. Within this proposed transport line there are 15 conventional solenoid, quadrupole and dipole magnets; as well as several specialty magnets, which transport and focus the beam to the target and to the beam dumps. There are two high power beam dumps, which are designed to absorb 80-kJ per pulse during accelerator start-up and operation. Aspects of the mechanical design of these elements are presented.
Carey, D.C.
1999-12-09
TURTLE is a computer program useful for determining many characteristics of a particle beam once an initial design has been achieved, Charged particle beams are usually designed by adjusting various beam line parameters to obtain desired values of certain elements of a transfer or beam matrix. Such beam line parameters may describe certain magnetic fields and their gradients, lengths and shapes of magnets, spacings between magnetic elements, or the initial beam accepted into the system. For such purposes one typically employs a matrix multiplication and fitting program such as TRANSPORT. TURTLE is designed to be used after TRANSPORT. For convenience of the user, the input formats of the two programs have been made compatible. The use of TURTLE should be restricted to beams with small phase space. The lumped element approximation, described below, precludes the inclusion of the effect of conventional local geometric aberrations (due to large phase space) or fourth and higher order. A reading of the discussion below will indicate clearly the exact uses and limitations of the approach taken in TURTLE.
Low energy beam transport system developments
Dudnikov, V.; Han, B.; Stockli, M.; Welton, R.; Dudnikova, G.
2015-04-08
For high brightness beam production it is important to preserve the brightness in the low energy beam transport system (LEBT) used to transport and match the ion beams to the next stage of acceleration, usually an RFQ. While electrostatic focusing can be problematic for high current beam transport, reliable electrostatic LEBT operation has been demonstrated with H{sup −} beams up to 60 mA. Now, however, it is commonly accepted that an optimal LEBT for high current accelerator applications consists of focusing solenoids with space charge compensation. Two-solenoid LEBTs are successfully used for high current (>100 mA) proton beam transport. Preservation of low emittances (~0.15 π mm-mrad) requires the addition of a heavy gas (Xe, Kr), which causes ~5% of proton loss in a 1 m long LEBT. Similar Xe densities would be required to preserve low emittances of H{sup −} beams, but such gas densities cause unacceptably high H{sup −} beam losses. A short LEBT with only one short solenoid, movable for RFQ matching, can be used for reduced negative ion stripping. A strong electrostatic-focusing LEBT has been successfully adopted for transport of high current H{sup −} beams in the SNS Front End. Some modifications of such electrostatic LEBTs are expected to improve the reliable transport of intense positive and negative ion beams without greatly degrading their low emittances. We concentrate on processes that determine the beam brightness degradation and on their prevention. Proposed improvements to the SNS electrostatic LEBT are discussed.
Chauvin, N.; Delferriere, O.; Duperrier, R.; Gobin, R.; Nghiem, P. A. P.; Uriot, D.
2012-02-15
Over the last few years, the interest of the international scientific community for high power accelerators in the megawatt range has been increasing. For such machines, the ion source has to deliver a beam intensity that ranges from several tens up to a hundred of mA. One of the major challenges is to extract and transport the beam while minimizing the emittance growth and optimizing its injection into the radio frequency quadrupole. Consequently, it is crucial to perform precise simulations and cautious design of the low energy beam transport (LEBT) line. In particular, the beam dynamics calculations have to take into account not only the space charge effects but also the space charge compensation of the beam induced by ionization of the residual gas. The physical phenomena occurring in a high intensity LEBT and their possible effects on the beam are presented, with a particular emphasis on space charge compensation. Then, beam transport issues in different kind of LEBTs are briefly reviewed. The SOLMAXP particle-in-cell code dedicated to the modeling of the transport of charge particles under a space charge compensation regime is described. Finally, beam dynamics simulations results obtained with SOLMAXP are presented in the case of international fusion materials irradiation facility injector.
Jang, Hyojae; Jin, Hyunchang; Jang, Ji-Ho; Hong, In-Seok
2016-02-01
A heavy ion accelerator, RAON is going to be built by Rare Isotope Science Project in Korea. Its target is to accelerate various stable ions such as uranium, proton, and xenon from electron cyclotron resonance ion source and some rare isotopes from isotope separation on-line. The beam shaping, charge selection, and modulation should be applied to the ions from these ion sources because RAON adopts a superconducting linear accelerator structure for beam acceleration. For such treatment, low energy beam transport, radio frequency quadrupole, and medium energy beam transport (MEBT) will be installed in injector part of RAON accelerator. Recently, development of a prototype of stripline beam position monitor (BPM) to measure the position of ion beams in MEBT section is under way. In this presentation, design of stripline, electromagnetic (EM) simulation results, and RF measurement test results obtained from the prototyped BPM will be described. PMID:26932088
NASA Astrophysics Data System (ADS)
Jang, Hyojae; Jin, Hyunchang; Jang, Ji-Ho; Hong, In-Seok
2016-02-01
A heavy ion accelerator, RAON is going to be built by Rare Isotope Science Project in Korea. Its target is to accelerate various stable ions such as uranium, proton, and xenon from electron cyclotron resonance ion source and some rare isotopes from isotope separation on-line. The beam shaping, charge selection, and modulation should be applied to the ions from these ion sources because RAON adopts a superconducting linear accelerator structure for beam acceleration. For such treatment, low energy beam transport, radio frequency quadrupole, and medium energy beam transport (MEBT) will be installed in injector part of RAON accelerator. Recently, development of a prototype of stripline beam position monitor (BPM) to measure the position of ion beams in MEBT section is under way. In this presentation, design of stripline, electromagnetic (EM) simulation results, and RF measurement test results obtained from the prototyped BPM will be described.
Self-pinched transport of an intense proton beam
Ottinger, P. F.; Young, F. C.; Stephanakis, S. J.; Rose, D. V.; Neri, J. M.; Weber, B. V.; Myers, M. C.; Hinshelwood, D. D.; Mosher, D.; Olson, C. L.
2000-01-01
Ion beam self-pinched transport (SPT) experiments have been carried out using a 1.1-MeV, 100-kA proton beam. A Rutherford scattering diagnostic and a LiF nuclear activation diagnostic measured the number of protons within a 5 cm radius at 50 cm into the transport region that was filled with low-pressure helium. Time-integrated signals from both diagnostics indicate self-pinching of the ion beam in a helium pressure window between 35 and 80 mTorr. Signals from these two diagnostics are consistent with ballistic transport at pressures above and below this SPT pressure window. Interferometric measurements of electron densities during beam injection into vacuum are consistent with ballistic transport with co-moving electrons. Interferometric measurements for beam injection into helium show that the electron density increases quadratically with pressure through the SPT window and roughly linearly with pressure above the SPT window. The ionization fraction of the helium plateaus at about 1.5% for pressures above 80 mTorr. In the SPT window, the electron density is 3 to 20 times the beam density. Numerical simulations of these beam transport experiments produce results that are in qualitative agreement with the experimental measurements. (c) 2000 American Institute of Physics.
NASA Astrophysics Data System (ADS)
Babu, P. Sing; Goswami, A.; Pandit, V. S.
2016-04-01
The dynamics of space-charge-dominated low energy proton beam in the presence of H2+ and H3+ beams has been studied in a solenoid based transport system using particle-in-cell (PIC) simulation method. Multispecies envelope equation and random search technique have been used to transport and match the primary beam considering two options. The PIC simulation shows the formation of hollow distribution of H2+ and H3+ beams around the proton beam in the first case where the waist of the proton beam is formed in between the solenoids and it is absent in the second case where the beam size is kept large in between the solenoids. Separation of hollow distribution appears more distinct as the proton fraction is increased and is almost independent of the combination of H2+ and H3+ beams for a given proton fraction. This effect helps to reject the unwanted species more effectively. The evolution of rms size and emittance of the proton beam has been studied in the presence of a circular aperture using KV and Gaussian distributions for the species in both the cases.
Investigation of electron beam transport in a helical undulator
Jeong, Y.U.; Lee, B.C.; Kim, S.K.
1995-12-31
Lossless transport of electrons through the undulator is essential for CW operation of the FELs driven by recirculating electrostatic accelerators. We calculate the transport ratio of an electron beam in a helical undulator by using a 3-D simulation code and compare the results with the experimental results. The energy and the current of the electron beam are 400 keV and 2 A, respectively. The 3-D distribution of the magnetic field of a practical permanent-magnet helical undulator is measured and is used in the calculations. The major parameters of the undutlator are : period = 32 mm, number of periods = 20, number of periods in adiabatic region = 3.5, magnetic field strength = 1.3 kG. The transport ratio is very sensitive to the injection condition of the electron beam such as the emittance, the diameter, the divergence, etc.. The injection motion is varied in the experiments by changing the e-gun voltage or the field strength of the focusing magnet located at the entrance of the undulator. It is confirmed experimentally and with simulations that most of the beam loss occurs at the adiabatic region of the undulator regardless of the length of the adiabatic region The effect of axial guiding magnetic field on the beam finish is investigated. According to the simulations, the increase of the strength of axial magnetic field from 0 to 1 kG results in the increase of the transport ratio from 15 % to 95%.
Advanced beam-dynamics simulation tools for RIA.
Garnett, R. W.; Wangler, T. P.; Billen, J. H.; Qiang, J.; Ryne, R.; Crandall, K. R.; Ostroumov, P.; York, R.; Zhao, Q.; Physics; LANL; LBNL; Tech Source; Michigan State Univ.
2005-01-01
We are developing multi-particle beam-dynamics simulation codes for RIA driver-linac simulations extending from the low-energy beam transport (LEBT) line to the end of the linac. These codes run on the NERSC parallel supercomputing platforms at LBNL, which allow us to run simulations with large numbers of macroparticles. The codes have the physics capabilities needed for RIA, including transport and acceleration of multiple-charge-state beams, beam-line elements such as high-voltage platforms within the linac, interdigital accelerating structures, charge-stripper foils, and capabilities for handling the effects of machine errors and other off-normal conditions. This year will mark the end of our project. In this paper we present the status of the work, describe some recent additions to the codes, and show some preliminary simulation results.
Sonic simulation of the SPS power beam
NASA Technical Reports Server (NTRS)
Ott, J. H.; Rice, J. S.
1981-01-01
A Satellite Power System Microwave Transmission Simulator is described. The simulator generates and transmits a beam audible sound energy which is mathematically similar to the microwave beam which would transmit energy to Earth from a Solar Power Satellite. This allows areas such as power beam formation to be studied in a laboratory environment.
NASA Astrophysics Data System (ADS)
Rimbault, C.; Le Meur, G.; Blampuy, F.; Bambade, P.; Schulte, D.
2009-12-01
Depolarization is a new feature in the beam-beam simulation tool GUINEA-PIG++ (GP++). The results of this simulation are studied and compared with another beam-beam simulation tool, CAIN, considering different beam parameters for the International Linear Collider (ILC) with a centre-of-mass energy of 500 GeV.
High current ion beam transport using solenoids
Hollinger, R.; Spaedtke, P.
2008-02-15
In the framework of the future project FAIR several upgrade programs and construction of new facilities are in progress such as the U{sup 4+} upgrade for the existing high current injector and the new 70 MeV proton injector. For both injectors solenoids in the low energy beam transport section are foreseen to inject the beam into the following rf accelerator. The paper presents beam quality measurements of high current ion beams behind a solenoid using a slit-grid emittance measurement device, viewing targets, and a pepper pot measurement device at the high current test bench at GSI.
Beam-Beam Simulations with the Gaussian Code TRS
Matter, Regina S.
2000-06-26
The authors have summarized the main features of the beam-beam simulation code TRS and presented two sample applications to the PEP-II collider. The code has been successfully tested against analytic results and against other simulation codes whenever such comparisons are meaningful. The soft-gaussian approximation is believed to represent reliably incoherent beam-beam effects. The code has been used to perform studies for the PEP-II collider. For example, simulated tune scans reveal undesirable operating points due to beam blowup from synchrotron sidebands. The dynamical beta effect, clearly seen in these simulations, also influences the choice of a working point. The code has been used to establish the adequate beam separation at the parasitic collision points [24], and has been applied to the proposed muon collider [25], including the effects from the instability of the muon.
Beam handling and transport solutions
Maggiore, M.; Cirrone, G. A. P.; Schillaci, F.; Scuderi, V.; Carpinelli, M.; Tramontana, A.
2013-07-26
The main purpose of the present study is to investigate the possibility to characterize the particle beams produced by the laser-target interaction in terms of collection, focusing and energy selection in order to evaluate the feasibility of a laser-driven facility in the field of medical application and, in particular, for hadrontherapy.
BEAM TRANSPORT LINES FOR THE BSNS.
WEI, J.
2006-06-26
This paper presents the design of two beam transport lines at the BSNS: one is the injection line from the Linac to the RCS and the other is the target line from the RCS to the target station. In the injection beam line, space charge effects, transverse halo collimation, momentum tail collimation and debunching are the main concerned topics. A new method of using triplet cells and stripping foils is used to collimate transverse halo. A long straight section is reserved for the future upgrading linac and debuncher. In the target beam line, large halo emittance, beam stability at the target due to kicker failures and beam jitters, shielding of back-scattering neutrons from the target are main concerned topics. Special bi-gap magnets will be used to reduce beam losses in the collimators in front of the target.
Recent advances of strong-strong beam-beam simulation
Qiang, Ji; Furman, Miguel A.; Ryne, Robert D.; Fischer, Wolfram; Ohmi,Kazuhito
2004-09-15
In this paper, we report on recent advances in strong-strong beam-beam simulation. Numerical methods used in the calculation of the beam-beam forces are reviewed. A new computational method to solve the Poisson equation on nonuniform grid is presented. This method reduces the computational cost by a half compared with the standard FFT based method on uniform grid. It is also more accurate than the standard method for a colliding beam with low transverse aspect ratio. In applications, we present the study of coherent modes with multi-bunch, multi-collision beam-beam interactions at RHIC. We also present the strong-strong simulation of the luminosity evolution at KEKB with and without finite crossing angle.
The role of space charge compensation for ion beam extraction and ion beam transport (invited)
Spädtke, Peter
2014-02-15
Depending on the specific type of ion source, the ion beam is extracted either from an electrode surface or from a plasma. There is always an interface between the (almost) space charge compensated ion source plasma, and the extraction region in which the full space charge is influencing the ion beam itself. After extraction, the ion beam is to be transported towards an accelerating structure in most cases. For lower intensities, this transport can be done without space charge compensation. However, if space charge is not negligible, the positive charge of the ion beam will attract electrons, which will compensate the space charge, at least partially. The final degree of Space Charge Compensation (SCC) will depend on different properties, like the ratio of generation rate of secondary particles and their loss rate, or the fact whether the ion beam is pulsed or continuous. In sections of the beam line, where the ion beam is drifting, a pure electrostatic plasma will develop, whereas in magnetic elements, these space charge compensating electrons become magnetized. The transport section will provide a series of different plasma conditions with different properties. Different measurement tools to investigate the degree of space charge compensation will be described, as well as computational methods for the simulation of ion beams with partial space charge compensation.
Particle Simulations of DARHT-II Transport System
Poole, B; Chen, Y J
2001-06-11
The DARHT-II beam line utilizes a fast stripline kicker to temporally chop a high current electron beam from a single induction LINAC and deliver multiple temporal electron beam pulses to an x-ray converter target. High beam quality needs to be maintained throughout the transport line from the end of the accelerator through the final focus lens to the x-ray converter target to produce a high quality radiographic image. Issues that will affect beam quality such as spot size and emittance at the converter target include dynamic effects associated with the stripline kicker as well as emittance growth due to the nonlinear forces associated with the kicker and various focusing elements in the transport line. In addition, dynamic effects associated with transverse resistive wall instability as well as gas focusing will affect the beam transport. A particle-in-cell code is utilized to evaluate beam transport in the downstream transport line in DARHT-II. External focusing forces are included utilizing either analytic expressions or field maps. Models for wakefields from the beam kicker, transverse resistive wall instability, and gas focusing are included in the simulation to provide a more complete picture of beam transport in DARHT-II. From these simulations, for various initial beam loads based on expected accelerator performance the temporally integrated target spot size and emittance can be estimated.
Beam transport and bunch compression at TARLA
NASA Astrophysics Data System (ADS)
Aksoy, Avni; Lehnert, Ulf
2014-10-01
The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) will operate two InfraRed Free Electron Lasers (IR-FEL) covering the range of 3-250 μm. The facility will consist of an injector fed by a thermionic triode gun with two-stage RF bunch compression, two superconducting accelerating ELBE modules operating at continuous wave (CW) mode and two independent optical resonator systems with different undulator period lengths. The electron beam will also be used to generate Bremsstrahlung radiation. In this study, we present the electron beam transport including beam matching to the undulators and the shaping of the longitudinal phase space using magnetic dispersive sections.
Simulations of beam-beam and beam-wire interactions in RHIC
Kim, Hyung J.; Sen, Tanaji; Abreu, Natalia P.; Fischer, Wolfram; /Brookhaven
2009-02-01
The beam-beam interaction is one of the dominant sources of emittance growth and luminosity lifetime deterioration. A current carrying wire has been proposed to compensate long-range beam-beam effects in the LHC and strong localized long-range beam-beam effects are experimentally investigated in the RHIC collider. Tune shift, beam transfer function, and beam loss rate are measured in dedicated experiments. In this paper, they report on simulations to study the effect of beam-wire interactions based on diffusive apertures, beam loss rates, and beam transfer function using a parallelized weak-strong beam simulation code (BBSIMC). The simulation results are compared with measurements performed in RHIC during 2007 and 2008.
Conditioner for a helically transported electron beam
Wang, C.
1992-05-01
The kinetic theory is developed to investigate a conditioner for a helically imported electron beam. Linear expressions for axial velocity spread are derived. Numerical simulation is used to check the theoretical results and examine nonlinear aspects of the conditioning process. The results show that in the linear regime the action of the beam conditioner on a pulsed beam mainly depends on the phase at which the beam enters the conditioner and depends only slightly on the operating wavelength. In the nonlinear regime, however, the action of the conditioner strongly depends on the operating wavelength and only slightly upon the entrance phase. For a properly chosen operating wavelength, a little less than the electron's relativistic cyclotron wavelength, the conditioner can decrease the axial velocity spread of a pulsed beam down to less than one-third of its initial value.
Conditioner for a helically transported electron beam
Wang, C.
1992-05-01
The kinetic theory is developed to investigate a conditioner for a helically imported electron beam. Linear expressions for axial velocity spread are derived. Numerical simulation is used to check the theoretical results and examine nonlinear aspects of the conditioning process. The results show that in the linear regime the action of the beam conditioner on a pulsed beam mainly depends on the phase at which the beam enters the conditioner and depends only slightly on the operating wavelength. In the nonlinear regime, however, the action of the conditioner strongly depends on the operating wavelength and only slightly upon the entrance phase. For a properly chosen operating wavelength, a little less than the electron`s relativistic cyclotron wavelength, the conditioner can decrease the axial velocity spread of a pulsed beam down to less than one-third of its initial value.
A Computer Study of Beam Transport by Solenoids
NASA Astrophysics Data System (ADS)
Chan, Chun Fai; Lee, Edward P.
1997-11-01
Beam transport by solenoids provides an alternative to the use of electrostatic quadrupole arrays that has been less studied for applications to heavy ion fusion drivers. A 1-d code (named SALT, for Solenoid Applications to Linac Transport) has been developed to simulate the axisymmetric beam dynamics through a sequence of solenoids. The beam is modeled as a set of ringlets, with radius and momentum traced in the axial coordinate. Solenoid fringe field aberrations, envelope matching, phase space evolution and emittance growth are studied using relativistically correct equations that include the electric and magnetic fields of the beam. Initial application is to the transport of a 2 MeV, 31.10 Ampere of K^+ beam through a channel of strength 6 Tesla. This implies a line charge density of 10 μC/m, a factor of 40 above the realistic limit for electrostatic quadrupoles. A second application is to the focusing of a 20 MeV, 4 kA electron beam down to its emittance limit.
Simulation studies of emittance growth in RMS mismatched beams
Cucchetti, A.; Wangler, T. ); Reiser, M. )
1991-01-01
As shown in a separate paper, a charged-particle beam, whose rms size is not matched when injected into a transport channel or accelerator, has excess energy compared with that of a matched beam. If nonlinear space-charge forces are present and the mismatched beam transforms to a matched equilibrium state, rms-emittance growth will occur. The theory yields formulas for the possible rms-emittance growth, but not for the time it takes to achieve this growth. In this paper we present the results of systematic simulation studies for a mismatched 2-D round beam in an ideal transport channel with continuous linear focusing. Emittance growth rates obtained from the simulations for different amounts of mismatch and initial charge will be presented and the emittance growth will be compared with the theory. 6 refs., 7 figs.
Macroparticle simulation studies of a proton beam haloexperiment
Qiang, J.; Colestock, P.L.; Gilpatrick, D.; Smith, H.V.; Wangler,T.P.; Schulze, M.E.
2002-09-12
We report macroparticle simulations for comparison withmeasured results from a proton beam-halo experiment in a 52-quadrupoleperiodic-focusing channel. An important issue is that the inputphase-space distribution is not experimentally known. Three differentinitial distributions with different shapes predict different beamprofiles in the transport system. Simulations have been fairly successfulin reproducing the core of the measured matched-beam profiles and thetrend of emittance growth as a function of mismatch factor, butunderestimate the growth rate of halo and emittance for mismatched beams.In this study, we find that knowledge of the Courant-Snyder parametersand emittances of the input beam is not sufficient for reliableprediction of the halo. Input distributions iwth greater population inthe tails produce larger rates of emittance growth, a result that isqualitatively consistent with the particle-core model of halo formationin mismatched beams.
Beam-Beam Interaction Simulations with Guinea Pig (LCC-0125)
Sramek, C
2003-11-20
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. 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 cross-sections ({sigma}{sub x}, {sigma}{sub y}, {sigma}{sub z}) and number of particles per bunch (N). Finally, this same study revealed luminosity maxima at large N and small {sigma}{sub y} which may merit further investigation.
Kinetic Simulations of Ion Beam Neutralization
Wang, Joseph
2010-05-21
Ion beam emission/neutralization is one of the most fundamental problems in spacecraft plasma interactions and electric propulsion. Although ion beam neutralization is readily achieved in experiments, the understanding of the underlying physical process remains at a rather primitive level. No theoretical or simulation models have convincingly explained the detailed neutralization mechanism, and no conclusions have been reached. This paper presents a fully kinetic simulation of ion beam neutralization and plasma beam propagation and discusses the physics of electron-ion coupling and the resulting propagation of a neutralized mesothermal plasma.
NASA Astrophysics Data System (ADS)
Taozheng
2015-08-01
In recent years, due to the high stability and privacy of vortex beam, the optical vortex became the hot spot in research of atmospheric optical transmission .We numerically investigate the propagation of vector elliptical vortex beams in turbulent atmosphere. Numerical simulations are realized with random phase screen. To simulate the vortex beam transport processes in the atmospheric turbulence. Using numerical simulation method to study in the atmospheric turbulence vortex beam transmission characteristics (light intensity, phase, polarization, etc.) Our simulation results show that, vortex beam in the atmospheric transmission distortion is small, make elliptic vortex beam for space communications is a promising strategy.
HZE beam transport in multilayered materials
NASA Technical Reports Server (NTRS)
Shinn, J. L.; Wilson, J. W.; Badavi, F. F.; Benton, E. V.; Csige, I.; Frank, A. L.; Benton, E. R.
1995-01-01
A nonperturbative analytic solution of the high charge and energy (HZE) Green's function is used to implement a computer code for laboratory ion beam transport in multiple-layered materials. The code is established to operate on the Langley nuclear fragmentation model used in space engineering applications. Computational procedures are established to generate linear energy transfer (LET) distributions for a specified ion beam and target for comparison with experimental measurement. Comparison with Fe-56 ion with Pb-Al and Pb-(CH2)(x) targets shows reasonable agreement.
Beam Dynamics Design and Simulation in Ion Linear Accelerators (
2006-08-01
Orginally, the ray tracing code TRACK has been developed to fulfill the many special requirements for the Rare Isotope Accelerator Facility known as RIA. Since no available beam-dynamics code met all the necessary requirements, modifications to the code TRACK were introduced to allow end-to-end (from the ion souce to the production target) simulations of the RIA machine, TRACK is a general beam-dynamics code and can be applied for the design, commissioning and operation of modernmore » ion linear accelerators and beam transport systems.« less
Beam Dynamics Design and Simulation in Ion Linear Accelerators (
Ostroumov, Peter N.; Asseev, Vladislav N.; Mustapha, and Brahim
2006-08-01
Orginally, the ray tracing code TRACK has been developed to fulfill the many special requirements for the Rare Isotope Accelerator Facility known as RIA. Since no available beam-dynamics code met all the necessary requirements, modifications to the code TRACK were introduced to allow end-to-end (from the ion souce to the production target) simulations of the RIA machine, TRACK is a general beam-dynamics code and can be applied for the design, commissioning and operation of modern ion linear accelerators and beam transport systems.
Kinetic Simulations of Ion Beam Neutralization
Chang, O.; Wang, J.
2011-05-20
Full particle PIC simulations are performed to study the neutralization of an ion beam in the cohesionless, mesothermal regime. Simulations further confirmed that neutralization is achieved through interactions between the trapped electrons and the potential well established by the propagation of the beam front along the beam direction and is not through plasma instabilities as previous studies suggested. In the transverse direction, the process is similar to that of the expansion of mesothermal plasma into vacuum. Parametric simulations are also performed to investigate the effects of beam radius and domain boundary condition on the neutralization process. The results suggests that, while the qualitative behavior may be similar in ground tests, quantitative parameters such as the beam potential will be affected significantly by the vacuum chamber because of the limits imposed on the expansion process by the finite chamber space.
BEAM-BEAM SIMULATIONS FOR THE ERHIC ELECTRON RING.
MONTAG, C.
2005-05-16
To study collisions between polarized electrons and heavy ions or polarized protons at high energy, adding a 10 GeV electron storage ring to the existing RHIC facility is currently under consideration. To achieve high luminosities of several 10{sup 33} cm{sup -2} sec{sup -1} range, a vertical beam-beam tuneshift parameter of {zeta}{sub y} = 0.08 is required for the electron beam. Simulation studies are being performed to study the feasibility of this high tuneshift parameter and explore the potential for even higher tuneshifts. Recent results of these studies are presented.
Simulation of a beam rotation system for a spallation source
NASA Astrophysics Data System (ADS)
Reiss, Tibor; Reggiani, Davide; Seidel, Mike; Talanov, Vadim; Wohlmuther, Michael
2015-04-01
With a nominal beam power of nearly 1 MW on target, the Swiss Spallation Neutron Source (SINQ), ranks among the world's most powerful spallation neutron sources. The proton beam transport to the SINQ target is carried out exclusively by means of linear magnetic elements. In the transport line to SINQ the beam is scattered in two meson production targets and as a consequence, at the SINQ target entrance the beam shape can be described by Gaussian distributions in transverse x and y directions with tails cut short by collimators. This leads to a highly nonuniform power distribution inside the SINQ target, giving rise to thermal and mechanical stresses. In view of a future proton beam intensity upgrade, the possibility of homogenizing the beam distribution by means of a fast beam rotation system is currently under investigation. Important aspects which need to be studied are the impact of a rotating proton beam on the resulting neutron spectra, spatial flux distributions and additional—previously not present—proton losses causing unwanted activation of accelerator components. Hence a new source description method was developed for the radiation transport code MCNPX. This new feature makes direct use of the results from the proton beam optics code TURTLE. Its advantage to existing MCNPX source options is that all phase space information and correlations of each primary beam particle computed with TURTLE are preserved and transferred to MCNPX. Simulations of the different beam distributions together with their consequences in terms of neutron production are presented in this publication. Additionally, a detailed description of the coupling method between TURTLE and MCNPX is provided.
Beam transport design for a recirculating-linac FEL driver
Neuffer, D.; Douglas, D.; Li, Z.; Cornacchia, M.; Garren, A.
1996-07-01
The beam transport system for the CEBAF Industrial FEL includes a two-pass transport of the beam with acceleration from injector to wiggler, followed by energy recovery transport from wiggler to dump. From that context, the authors discuss the general problem of multi-pass energy-recovery beam transport for FELs. Tunable, nearly-isochronous, large-momentum-acceptance transport systems are required. The entire transport must preserve beam quality, particularly in the acceleration transport to the wiggler, and have low losses throughout the entire system. Various possible designs are presented, and results of dynamic analyses are discussed.
Basten, M.A.; Booske, J.H.; Anderson, J.; Scharer, J.E.
1995-11-01
Sheet electron beams and configurations with multiple electron beams have the potential to make possible higher power sources of microwave radiation due to their ability to transport high currents, at reduced current densities, through a single RF interaction circuit. Possible microwave device applications using sheet electron beams include sheet-beam klystrons, rectangular grating circuits, and planar FELS. Historically, implementation of sheet beams in microwave devices has been discouraged by their susceptibility to the diocotron instability in solenoidal focusing systems. However, recent theoretical and numerical studies have shown that stable transport of sheet beams is possible, in periodically cusped magnetic (PCM) fields. The use of an offset-pole PCM configuration has been shown analytically to provide side-fields for 2-D focusing of the beam, and this has been recently verified with PIC code simulations. The authors will present further theoretical studies of sheet and multi-beam transport and discuss results from an experimental investigation of the formation, stability and transport of PCM-focused sheet electron beams. This includes a laboratory method of forming an elliptical sheet beam using a magnetic quadrupole pair and a round-beam Pierce gun.
Beam transport of low temperature atomic hydrogen
NASA Astrophysics Data System (ADS)
Kaufman, W. A.
1993-12-01
Analytic calculations and particle tracking simulations are presented for a polarized atomic hydrogen beam produced by extraction from an ultra-cold (T=300 mK) helium film coated cell in a large solenoidal magnetic field (12 T). Initial focusing of states 1 and 2 by the solenoidal field and subsequent focusing by a sextupole are examined within the constraints imposed by the requirements of the polarized jet for the experiments NEPTUN and NEPTUN-A at UNK.
Beam Simulation Studies of the LEBT for RIA Driver Linac
Zhao, Q.; Wu, X.; Andreev, V.; Balabin, A.; Doleans, M.; Gorelov, D.; Grimm, T.L.; Hartung, W.; Marti, F.; Schriber, S.O.; York, R.C.; Leitner, D.; Lyneis, C.M.
2005-03-15
The low energy beam transport (LEBT) system in the front-end of the Rare Isotope Accelerator (RIA) uses a 70 kV platform to pre-accelerate the ion beam from a 30 kV Electron Cyclotron Resonance (ECR) ion source, followed by an achromatic charge selection system. The selected beam is then pre-bunched and matched into the entrance of a Radio Frequency Quadrupole (RFQ) with a multi-harmonic buncher. To meet the beam power requirements for heavy ions, high current (several mA), multi-species beams will be extracted from the ECR. Therefore, it is crucial to control space charge effects in order to obtain the low emittance beam required for RIA. The PARMELA code is used to perform the LEBT simulations for the multi-species beams with 3D space charge calculations. The results of the beam dynamics simulations are presented, and the key issues of emittance growth in the LEBT and its possible compensation are discussed.
A Green's function method for heavy ion beam transport
NASA Technical Reports Server (NTRS)
Shinn, J. L.; Wilson, J. W.; Schimmerling, W.; Shavers, M. R.; Miller, J.; Benton, E. V.; Frank, A. L.; Badavi, F. F.
1995-01-01
The use of Green's function has played a fundamental role in transport calculations for high-charge high-energy (HZE) ions. Two recent developments have greatly advanced the practical aspects of implementation of these methods. The first was the formulation of a closed-form solution as a multiple fragmentation perturbation series. The second was the effective summation of the closed-form solution through nonperturbative techniques. The nonperturbative methods have been recently extended to an inhomogeneous, two-layer transport media to simulate the lead scattering foil present in the Lawrence Berkeley Laboratories (LBL) biomedical beam line used for cancer therapy. Such inhomogeneous codes are necessary for astronaut shielding in space. The transport codes utilize the Langley Research Center atomic and nuclear database. Transport code and database evaluation are performed by comparison with experiments performed at the LBL Bevalac facility using 670 A MeV 20Ne and 600 A MeV 56Fe ion beams. The comparison with a time-of-flight and delta E detector measurement for the 20Ne beam and the plastic nuclear track detectors for 56Fe show agreement up to 35%-40% in water and aluminium targets, respectively.
A Green's function method for heavy ion beam transport.
Shinn, J L; Wilson, J W; Schimmerling, W; Shavers, M R; Miller, J; Benton, E V; Frank, A L; Badavi, F F
1995-08-01
The use of Green's function has played a fundamental role in transport calculations for high-charge high-energy (HZE) ions. Two recent developments have greatly advanced the practical aspects of implementation of these methods. The first was the formulation of a closed-form solution as a multiple fragmentation perturbation series. The second was the effective summation of the closed-form solution through nonperturbative techniques. The nonperturbative methods have been recently extended to an inhomogeneous, two-layer transport media to simulate the lead scattering foil present in the Lawrence Berkeley Laboratories (LBL) biomedical beam line used for cancer therapy. Such inhomogeneous codes are necessary for astronaut shielding in space. The transport codes utilize the Langley Research Center atomic and nuclear database. Transport code and database evaluation are performed by comparison with experiments performed at the LBL Bevalac facility using 670 A MeV 20Ne and 600 A MeV 56Fe ion beams. The comparison with a time-of-flight and delta E detector measurement for the 20Ne beam and the plastic nuclear track detectors for 56Fe show agreement up to 35%-40% in water and aluminium targets, respectively. PMID:7480630
Transport in JET H-mode Plasmas with Beam and Ion Cyclotron Heating
R.V. Budny, et. al.
2012-07-13
Ion Cyclotron (IC) Range of Frequency waves and neutral beam (NB) injection are planned for heating in ITER and other future tokamaks. It is important to understand transport in plasmas with NB and IC to plan, predict, and improve transport and confinement. Transport predictions require simulations of the heating profiles, and for this, accurate modeling of the IC and NB heating is needed.
W-band sheet beam klystron simulation
Colby, E.R.; Caryotakis, G.; Fowkes, W.R.; Smithe, D.N.
1999-05-01
With the development of ever higher energy particle accelerators comes the need for compactness and high gradient, which in turn require very high frequency high power rf sources. Recent development work in W-band accelerating techniques has spurred the development of a high-power W-band source. Axisymmetric sources suffer from fundamental power output limitations (P{sub sat}{approximately}{lambda}{sup 2}) brought on by the conflicting requirements of small beam sizes and high beam current. The sheet beam klystron allows for an increase in beam current without substantial increase in the beam current density, allowing for reduced cathode current densities and focussing field strengths. Initial simulations of a 20:1 aspect ratio sheet beam/cavity interaction using the 3 dimensional particle-in-cell code Magic3D have demonstrated a 35{percent} beam-power to RF power extraction efficiency. Calculational work and numerical simulations leading to a prototype W-band sheet beam klystron will be presented, together with preliminary cold test structure studies of a proposed RF cavity geometry. {copyright} {ital 1999 American Institute of Physics.}
W-Band Sheet Beam Klystron Simulation
Colby, E.R.; Caryotakis, G.; Fowkes, W.R.; Smithe, D.N.; /Mission Res., Newington
2005-09-12
With the development of ever higher energy particle accelerators comes the need for compactness and high gradient, which in turn require very high frequency high power rf sources. Recent development work in W-band accelerating techniques has spurred the development of a high-power W-band source. Axisymmetric sources suffer from fundamental power output limitations (P{sub sat} {approx} {lambda}{sup 2}) brought on by the conflicting requirements of small beam sizes and high beam current. The sheet beam klystron allows for an increase in beam current without substantial increase in the beam current density, allowing for reduced cathode current densities and focusing field strengths. Initial simulations of a 20:1 aspect ratio sheet beam/cavity interaction using the 3 dimensional particle-in-cell code Magic3D have demonstrated a 35% beam-power to RF power extraction efficiency. Calculational work and numerical simulations leading to a prototype W-band sheet beam klystron will be presented, together with preliminary cold test structure studies of a proposed RF cavity geometry.
High-powered pulsed-ion-beam acceleration and transport
Humphries, S. Jr.; Lockner, T.R.
1981-11-01
The state of research on intense ion beam acceleration and transport is reviewed. The limitations imposed on ion beam transport by space charge effects and methods available for neutralization are summarized. The general problem of ion beam neutralization in regions free of applied electric fields is treated. The physics of acceleration gaps is described. Finally, experiments on multi-stage ion acceleration are summarized.
Electrons in a positive-ion beam with solenoid or quadrupole magnetic transport
Molvik, A.W.; Kireeff Covo, M.; Cohen, R.; Coleman, J.; Sharp, W.; Bieniosek, F.; Friedman, A.; Roy, P.K.; Seidl, P.; Lund, S.M.; Faltens, A.; Vay, J.L.; Prost, L.
2007-06-04
The High Current Experiment (HCX) is used to study beam transport and accumulation of electrons in quadrupole magnets and the Neutralized Drift-Compression Experiment (NDCX) to study beam transport through and accumulation of electrons in magnetic solenoids. We find that both clearing and suppressor electrodes perform as intended, enabling electron cloud densities to be minimized. Then, the measured beam envelopes in both quadrupoles and solenoids agree with simulations, indicating that theoretical beam current transport limits are reliable, in the absence of electrons. At the other extreme, reversing electrode biases with the solenoid transport effectively traps electrons; or, in quadrupole magnets, grounding the suppressor electrode allows electron emission from the end wall to flood the beam, in both cases producing significant degradation in the beam.
Electrons in a Positive-Ion Beam with Solenoid or Quadrupole Magnet Transport
Molvik, A W; Cohen, R H; Friedman, A; Covo, M K; Lund, S M; Sharp, W M; Seidl, P A; Bieniosek, F M; Coleman, J E; Faltens, A; Roy, P K; Vay, J L; Prost, L
2007-06-01
The High Current Experiment (HCX) is used to study beam transport and accumulation of electrons in quadrupole magnets and the Neutralized Drift-Compression Experiment (NDCX) to study beam transport through and accumulation of electrons in magnetic solenoids. We find that both clearing and suppressor electrodes perform as intended, enabling electron cloud densities to be minimized. Then, the measured beam envelopes in both quadrupoles and solenoids agree with simulations, indicating that theoretical beam current transport limits are reliable, in the absence of electrons. At the other extreme, reversing electrode biases with the solenoid transport effectively traps electrons; or, in quadrupole magnets, grounding the suppressor electrode allows electron emission from the end wall to flood the beam, in both cases producing significant degradation in the beam.
Transport of a high brightness proton beam through the Munich tandem accelerator
NASA Astrophysics Data System (ADS)
Moser, M.; Greubel, C.; Carli, W.; Peeper, K.; Reichart, P.; Urban, B.; Vallentin, T.; Dollinger, G.
2015-04-01
Basic requirement for ion microprobes with sub-μm beam focus is a high brightness beam to fill the small phase space usually accepted by the ion microprobe with enough ion current for the desired application. We performed beam transport simulations to optimize beam brightness transported through the Munich tandem accelerator. This was done under the constraint of a maximum ion current of 10 μA that is allowed to be injected due to radiation safety regulations and beam power constrains. The main influence of the stripper foil in conjunction with intrinsic astigmatism in the beam transport on beam brightness is discussed. The calculations show possibilities for brightness enhancement by using astigmatism corrections and asymmetric filling of the phase space volume in the x- and y-direction.
Simulation based analysis of laser beam brazing
NASA Astrophysics Data System (ADS)
Dobler, Michael; Wiethop, Philipp; Schmid, Daniel; Schmidt, Michael
2016-03-01
Laser beam brazing is a well-established joining technology in car body manufacturing with main applications in the joining of divided tailgates and the joining of roof and side panels. A key advantage of laser brazed joints is the seam's visual quality which satisfies highest requirements. However, the laser beam brazing process is very complex and process dynamics are only partially understood. In order to gain deeper knowledge of the laser beam brazing process, to determine optimal process parameters and to test process variants, a transient three-dimensional simulation model of laser beam brazing is developed. This model takes into account energy input, heat transfer as well as fluid and wetting dynamics that lead to the formation of the brazing seam. A validation of the simulation model is performed by metallographic analysis and thermocouple measurements for different parameter sets of the brazing process. These results show that the multi-physical simulation model not only can be used to gain insight into the laser brazing process but also offers the possibility of process optimization in industrial applications. The model's capabilities in determining optimal process parameters are exemplarily shown for the laser power. Small deviations in the energy input can affect the brazing results significantly. Therefore, the simulation model is used to analyze the effect of the lateral laser beam position on the energy input and the resulting brazing seam.
Simulation of beam-induced plasma for the mitigation of beam-beam effects
Ma, J.; Wang, G.; Samulyak, R.; Yu, K.; Litvinenko, V.
2015-05-03
One of the main challenges in the increase of luminosity of circular colliders is the control of the beam-beam effect. In the process of exploring beam-beam mitigation methods using plasma, we evaluated the possibility of plasma generation via ionization of neutral gas by proton beams, and performed highly resolved simulations of the beam-plasma interaction using SPACE, a 3D electromagnetic particle-in-cell code. The process of plasma generation is modelled using experimentally measured cross-section coefficients and a plasma recombination model that takes into account the presence of neutral gas and beam-induced electromagnetic fields. Numerically simulated plasma oscillations are consistent with theoretical analysis. In the beam-plasma interaction process, high-density neutral gas reduces the mean free path of plasma electrons and their acceleration. A numerical model for the drift speed as a limit of plasma electron velocity was developed. Simulations demonstrate a significant reduction of the beam electric field in the presence of plasma. Preliminary simulations using fully-ionized plasma have also been performed and compared with the case of beam-induced plasma.
Heavy ion beam transport in an inertial confinement fusion reactor
Barboza, N.
1995-08-01
A new code, bimc, is under development to determine if a beam of heavy ions can be focused to the necessary spot-size radius of about 2 mm within an inertial confinement reactor chamber where the background gas densities are on the order of 10{sup 14}--10{sup 15} cm{sup {minus}3} Lithium (or equivalent). Beam transport is expected to be strongly affected by stripping and collective plasma phenomena; however, if propagation is possible in this regime, it could lead to simplified reactor designs. The beam is modeled using a 2 1/2 D particle-in-cell (PIC) simulation code coupled with a Monte Carlo (MC) method for analyzing collisions. The MC code follows collisions between the beam ions and neutral background gas atoms that account for the generation of electrons and background gas ions (ionization), and an increase of the charge state of the beam ions (stripping). The PIC code models the complete dynamics of the interaction of the various charged particle species with the self generated electromagnetic fields. Details of the code model and preliminary results are presented.
Predictive Simulations of ITER Including Neutral Beam Driven Toroidal Rotation
Halpern, Federico D.; Kritz, Arnold H.; Bateman, Glenn; Pankin, Alexei Y.; Budny, Robert V.; McCune, Douglas C.
2008-06-16
Predictive simulations of ITER [R. Aymar et al., Plasma Phys. Control. Fusion 44, 519 2002] discharges are carried out for the 15 MA high confinement mode (H-mode) scenario using PTRANSP, the predictive version of the TRANSP code. The thermal and toroidal momentum transport equations are evolved using turbulent and neoclassical transport models. A predictive model is used to compute the temperature and width of the H-mode pedestal. The ITER simulations are carried out for neutral beam injection (NBI) heated plasmas, for ion cyclotron resonant frequency (ICRF) heated plasmas, and for plasmas heated with a mix of NBI and ICRF. It is shown that neutral beam injection drives toroidal rotation that improves the confinement and fusion power production in ITER. The scaling of fusion power with respect to the input power and to the pedestal temperature is studied. It is observed that, in simulations carried out using the momentum transport diffusivity computed using the GLF23 model [R.Waltz et al., Phys. Plasmas 4, 2482 (1997)], the fusion power increases with increasing injected beam power and central rotation frequency. It is found that the ITER target fusion power of 500 MW is produced with 20 MW of NBI power when the pedesta temperature is 3.5 keV. 2008 American Institute of Physics. [DOI: 10.1063/1.2931037
Transport and Non-Invasive Position Detection of Electron Beams from Laser-Plasma Accelerators
Osterhoff, Jens; Sokollik, Thomas; Nakamura, Kei; Bakeman, Michael; Weingartner, R; Gonsalves, Anthony; Shiraishi, Satomi; Lin, Chen; vanTilborg, Jeroen; Geddes, Cameron; Schroeder, Carl; Esarey, Eric; Toth, Csaba; DeSantis, Stefano; Byrd, John; Gruner, F; Leemans, Wim
2011-07-20
The controlled imaging and transport of ultra-relativistic electrons from laser-plasma accelerators is of crucial importance to further use of these beams, e.g. in high peak-brightness light sources. We present our plans to realize beam transport with miniature permanent quadrupole magnets from the electron source through our THUNDER undulator. Simulation results demonstrate the importance of beam imaging by investigating the generated XUV-photon flux. In addition, first experimental findings of utilizing cavity-based monitors for non-invasive beam-position measurements in a noisy electromagnetic laser-plasma environment are discussed.
Transport and Non-Invasive Position Detection of Electron Beams from Laser-Plasma Accelerators
Osterhoff, J.; Nakamura, K.; Bakeman, M.; Gonsalves, A. J.; Shiraishi, S.; Lin, C.; Tilborg, J. van; Geddes, C. G. R.; Schroeder, C. B.; Esarey, E.; Toth, Cs.; De Santis, S.; Byrd, J. M.; Leemans, W. P.; Sokollik, T.; Weingartner, R.; Gruener, F.
2010-11-04
The controlled imaging and transport of ultra-relativistic electrons from laser-plasma accelerators is of crucial importance to further use of these beams, e.g. in high peak-brightness light sources. We present our plans to realize beam transport with miniature permanent quadrupole magnets from the electron source through our THUNDER undulator. Simulation results demonstrate the importance of beam imaging by investigating the generated XUV-photon flux. In addition, first experimental findings of utilizing cavity-based monitors for non-invasive beam-position measurements in a noisy electromagnetic laser-plasma environment are discussed.
Radial particle distributions in PARMILA simulation beams
Boicourt, G.P.
1984-03-01
The estimation of beam spill in particle accelerators is becoming of greater importance as higher current designs are being funded. To the present, no numerical method for predicting beam-spill has been available. In this paper, we present an approach to the loss-estimation problem that uses probability distributions fitted to particle-simulation beams. The properties of the PARMILA code's radial particle distribution are discussed, and a broad class of probability distributions are examined to check their ability to fit it. The possibility that the PARMILA distribution is a mixture is discussed, and a fitting distribution consisting of a mixture of two generalized gamma distributions is found. An efficient algorithm to accomplish the fit is presented. Examples of the relative prediction of beam spill are given. 26 references, 18 figures, 1 table.
RHIC electron lens beam transport system design considerations
Gu, X.; Pikin, A.; Okamura, M.; Fischer, W.; Luo, Y.; Gupta, R.; Hock, J.; Jain, A.; Raparia, D.
2010-10-01
To apply head-on beam-beam compensation for RHIC, two electron lenses are designed and will be installed at IP10. Electron beam transport system is one of important subsystem, which is used to transport electron beam from electron gun side to collector side. This system should be able to change beam size inside superconducting magnet and control beam position with 5 mm in horizontal and vertical plane. Some other design considerations for this beam transport system are also reported in this paper. The head-on beam-beam effect is one of important nonlinear source in storage ring and linear colliders, which have limited the luminosity improvement of many colliders, such as SppS, Tevatron and RHIC. In order to enhance the performance of colliders, beam-beam effects can be compensated with direct space charge compensation, indirect space charge compensation or betatron phase cancellation scheme. Like other colliders, indirect space charge compensation scheme (Electron Lens) was also proposed for Relativistic Heavy Ion Collider (RHIC) beam-beam compensation at Brookhaven National Laboratory. The two similar electron lenses are located in IR10 between the DX magnets. One RHIC electron lens consists of one DC electron gun, one superconducting magnet, one electron collector and beam transport system.
Transport of intense beams of highly charged ions
NASA Astrophysics Data System (ADS)
Winkler, M.; Gammino, S.; Ciavola, G.; Celona, L.; Spadtke, P.; Tinschert, K.
2005-10-01
The new generation of ion sources delivers beams with intensities of several mA. This requires a careful design of the analysing system and the low-energy beam transport (LEBT) from the source to the subsequent systems. At INFN-LNS, high intensity proton sources (TRIPS [L. Celona, G. Ciavola, S. Gammino et al ., Rev. Sci. Instrum. 75(5) 1423 (2004)], PM-TRIPS [G. Ciavola, L. Celona, S. Gammino et al ., Rev. Sci. Instrum. 75(5) 1453 (2004)]) as well as ECR ion sources for the production of highly charged high-intensity heavy ion beams are developed (SERSE [S. Gammino, G. Ciavola, L. Celona et al ., Rev. Sci. Instrum. 72(11) 4090 (2001), and references therein], GyroSERSE [S. Gammino et al ., Rev. Sci. Instrum. 75(5) 1637 (2004)], MS-ECRIS [G. Ciavola et al ., (2005), 11th Int. Conf. on Ion Sources, Caen, (in press)]). In this paper, we present ion-optical design studies of various LEBT systems for ion-sources devoted to the production of intense beams. Calculations were performed using the computer codes GIOS [H. Wollnik, J. Brezina and M. Berz, NIM A 258 (1987)], GICO [M. Berz, H.C. Hoffmann, and H. Wollnik, NIM A 258 (1987)], and TRANSPORT [K.L. Brown, F. Rothacker and D.C. Carey, SLAC-R-95-462, Fermilab-Pub-95/069, UC-414 (1995)]. Simulations take into account the expected phase space growth of the beam emittance due to space-charge effects and image aberrations introduced by the magnetic elements.
Beam transport for an SRF recirculating-linac FEL
Neuffer, D.; Douglas, D.; Li, Z.
1995-12-31
The beam transport system for the CEBAF UV Demo FEL includes a two-pan transport of the beam with acceleration from injector to wiggler, followed by energy recovery transport from wiggler to dump. From that contact we discuss the general problem of multi-pass energy-recovery beam transport for FELs. Tuneable, nearly-isochronous, large-momentum-acceptance import systems are required. The entire transport must preserve beam quality, particularly in the acceleration transport to the wiggler, and have low losses throughout the entire system. Issues such as injection and final energies, number of passes, linac focusing effects, beam separation, chronicity management, and stability constraints are critical. Various possible designs are discussed. Particle tracking results exploring the design options are also reported.
Space charge compensation in the Linac4 low energy beam transport line with negative hydrogen ions
Valerio-Lizarraga, Cristhian A.; Lallement, Jean-Baptiste; Lettry, Jacques; Scrivens, Richard; Leon-Monzon, Ildefonso; Midttun, Øystein
2014-02-15
The space charge effect of low energy, unbunched ion beams can be compensated by the trapping of ions or electrons into the beam potential. This has been studied for the 45 keV negative hydrogen ion beam in the CERN Linac4 Low Energy Beam Transport using the package IBSimu [T. Kalvas et al., Rev. Sci. Instrum. 81, 02B703 (2010)], which allows the space charge calculation of the particle trajectories. The results of the beam simulations will be compared to emittance measurements of an H{sup −} beam at the CERN Linac4 3 MeV test stand, where the injection of hydrogen gas directly into the beam transport region has been used to modify the space charge compensation degree.
The Beam Break-Up Numerical Simulator
Travish, G.A.
1989-11-01
Beam Break-Up (BBU) is a severe constraint in accelerator design, limiting beam current and quality. The control of BBU has become the focus of much research in the design of the next generation collider, recirculating and linear induction accelerators and advanced accelerators. Determining the effect on BBU of modifications to cavities, the focusing elements or the beam is frequently beyond the ability of current analytic models. A computer code was written to address this problem. The Beam Break-Up Numerical Simulator (BBUNS) was designed to numerically solve for beam break-up (BBU) due to an arbitrary transverse wakefield. BBUNS was developed to be as user friendly as possible on the Cray computer series. The user is able to control all aspects of input and output by using a single command file. In addition, the wakefield is specified by the user and read in as a table. The program can model energy variations along and within the beam, focusing magnetic field profiles can be specified, and the graphical output can be tailored. In this note we discuss BBUNS, its structure and application. Included are detailed instructions, examples and a sample session of BBUNS. This program is available for distribution. 50 refs., 18 figs., 5 tabs.
Simulation of Chamber Transport for Heavy-Ion-Fusion Drivers
Sharp, W M; Callahan, D A; Tabak, M; Yu, S S; Peterson, P F; Rose, D V; Welch, D R
2003-09-25
The heavy-ion fusion (HIF) community recently developed a power-plant design that meets the various requirements of accelerators, final focus, chamber transport, and targets. The point design is intended to minimize physics risk and is certainly not optimal for the cost of electricity. Recent chamber-transport simulations, however, indicate that changes in the beam ion species, the convergence angle, and the emittance might allow more-economical designs.
Transport Simulations for Fast Ignition on NIF
Strozzi, D J; Tabak, M; Grote, D P; Cohen, B I; Shay, H D; Town, R J; Kemp, A J; Key, M
2009-10-26
We are designing a full hydro-scale cone-guided, indirect-drive FI coupling experiment, for NIF, with the ARC-FIDO short-pulse laser. Current rad-hydro designs with limited fuel jetting into cone tip are not yet adequate for ignition. Designs are improving. Electron beam transport simulations (implicit-PIC LSP) show: (1) Magnetic fields and smaller angular spreads increase coupling to ignition-relevant 'hot spot' (20 um radius); (2) Plastic CD (for a warm target) produces somewhat better coupling than pure D (cryogenic target) due to enhanced resistive B fields; and (3) The optimal T{sub hot} for this target is {approx} 1 MeV; coupling falls by 3x as T{sub hot} rises to 4 MeV.
High-current beam dynamics and transport, theory and experiment
Reiser, M.
1986-01-01
Recent progress in the understanding of beam physics and technology factors determining the current and brightness of ion and electron beams in linear accelerators will be reviewed. Topics to be discussed including phase-space density constraints of particle sources, low-energy beam transport include charge neutralization, emittance growth due to mismatch, energy exchange, instabilities, nonlinear effects, and longitudinal bunching.
NASA Astrophysics Data System (ADS)
Jin, Hyunchang; Jang, Ji-Ho; Jang, Hyojae; Jeon, Dong-O.
2015-12-01
In RAON heavy ion accelerator, beams generated by superconducting electron cyclotron resonance ion source (ECR-IS) or Isotope Separation On-Line (ISOL) system are accelerated by lower energy superconducting linac and high energy superconducting linac. The accelerated beams are used in the high energy experimental hall which includes bio-medical and muon-SR facilities, after passing through the high energy beam transport lines. At the targets of those two facilities, the stable and small beams meeting the requirements rigorously are required in the transverse plane. Therefore the beams must be safely sent to the targets and simultaneously satisfy the two requirements, the achromatic condition and the mid-plane symmetric condition, of the targets. For this reason, the lattice design of the high energy beam transport lines in which the long deflecting sections are included is considered as a significant issue in the RAON accelerator. In this paper, we will describe the calculated beam optics satisfying the conditions and present the result of particle tracking simulations with the designed lattice of the high energy beam transport lines in the RAON accelerator. Also, the orbit distortion caused by the machine imperfections and the orbit correction with correctors will be discussed.
Low-energy beam transport studies supporting the Spallation Neutron Source 1-MW beam operationa
Han, Baoxi; Kalvas, T.; Tarvainen, O.; Welton, Robert F; Murray Jr, S N; Pennisi, Terry R; Santana, Manuel; Stockli, Martin P
2012-01-01
The H- injector consisting of a cesium enhanced RF-driven ion source and a 2-lens electrostatic low-energy beam transport (LEBT) system supports the Spallation Neutron Source 1-MW beam operation with ~38 mA beam current in the linac at 60 Hz with a pulse length of up to ~1.0 ms. In this work, two important issues associated with the low-energy beam transport are discussed: 1) inconsistent dependence of the post-RFQ beam current on the ion source tilt angle, and 2) high power beam losses on the LEBT electrodes under some off-nominal conditions compromising their reliability.
Experimental study of ion-beam self-pinched transport for MeV protons
Neri, J.M.; Young, F.C.; Stephanakis, S.J.; Ottinger, P.F.; Rose, D.V.; Hinshelwood, D.D.; Weber, B.V.
1999-07-01
A 100-kA, 1.2-MeV proton beam from a pinch-reflex ion diode on the Gamble II accelerator is used to test the concept of self-pinched ion transport. Self-pinched transport (SPT) uses the self-generated magnetic field from the ion beam to radially confine the ion beam. A proton beam is injected through a 3-cm radius aperture covered with a 2-{micro}m thick polycarbonate foil into a 10-cm radius transport region. The transport region is filled with helium at pressures of 30--250 mTorr, vacuum (10{sup {minus}4} Torr), or 1-Torr air. The beam is diagnosed with witness plates, multiple-pinhole-camera imaging onto radiochromic film, time- and space-resolved proton-scattering, and with prompt-{gamma} and nuclear-activation from LiF targets. Witness-plates and the multiple-pinhole-camera are used to determine the size, location, and uniformity of the beam at different distances from the injection aperture. A beam global divergence of 200 mrad is measured at 15 cm. At 50 cm, the beam fills the transport region. At 110 cm and 100- to 200-mTorr helium, there is evidence of beam filamentation. The measured increase in protons is consistent with the physical picture for SPT, and comparisons with IPROP simulations are in qualitative agreement with the measurements.
Integrated Transport Simulation of Burning Plasmas
Fukuyama, Atsushi
2009-02-19
In order to predict the behavior of burning plasmas and develop optimized operation scenarios of ITER, integrated modeling and simulation of fusion plasmas is indispensable. Transport process is one of the main issues in integrated modeling of burning plasmas. In this lecture, first, aim of the integrated simulation, research activities of integrated modeling, desired features of integrated simulation codes, and the integrated tokamak simulation code, TASK, are briefly described. Then the present role of transport modeling in the integrated modeling is discussed based on the time scale separation. Basic equations of the transport simulation coupled with the equilibrium analysis are explained. Modeling of transport phenomena, comparison of transport models, simulation of internal transport barrier formation are described. After brief discussion of source modeling, an example of burning plasma simulation. Finally remaining issues are discussed and summaries are given.
Collective microdynamics and noise suppression in dispersive electron beam transport
Gover, Avraham; Dyunin, Egor; Duchovni, Tamir; Nause, Ariel
2011-12-15
A general formulation is presented for deep collective interaction micro-dynamics in dispersive e-beam transport. In the regime of transversely coherent interaction, the formulation is applicable to both coherent and random temporal modulation of the electron beam. We demonstrate its use for determining the conditions for suppressing beam current noise below the classical shot-noise level by means of transport through a dispersive section with a small momentum compaction parameter.
Third-order TRANSPORT: A computer program for designing charged particle beam transport systems
Carey, D.C.; Brown, K.L.; Rothacker, F.
1995-05-01
TRANSPORT has been in existence in various evolutionary versions since 1963. The present version of TRANSPORT is a first-, second-, and third-order matrix multiplication computer program intended for the design of static-magnetic beam transport systems. This report discusses the following topics on TRANSPORT: Mathematical formulation of TRANSPORT; input format for TRANSPORT; summaries of TRANSPORT elements; preliminary specifications; description of the beam; physical elements; other transformations; assembling beam lines; operations; variation of parameters for fitting; and available constraints -- the FIT command.
Radiative transfer simulations of magnetar flare beaming
NASA Astrophysics Data System (ADS)
van Putten, T.; Watts, A. L.; Baring, M. G.; Wijers, R. A. M. J.
2016-05-01
Magnetar giant flares show oscillatory modulations in the tails of their light curves, which can only be explained via some form of beaming. The fireball model for magnetar bursts has been used successfully to fit the phase-averaged light curves of the tails of giant flares, but so far no attempts have been made to fit the pulsations. We present a relatively simple numerical model to simulate beaming of magnetar flare emission. In our simulations, radiation escapes from the base of a fireball trapped in a dipolar magnetic field, and is scattered through the optically thick magnetosphere of the magnetar until it escapes. Beaming is provided by the presence of a relativistic outflow, as well as by the geometry of the system. We find that a simple picture for the relativistic outflow is enough to create the pulse fraction and sharp peaks observed in pulse profiles of magnetar flares, while without a relativistic outflow the beaming is insufficient to explain giant flare rotational modulations.
Radiative transfer simulations of magnetar flare beaming
NASA Astrophysics Data System (ADS)
van Putten, T.; Watts, A. L.; Baring, M. G.; Wijers, R. A. M. J.
2016-09-01
Magnetar giant flares show oscillatory modulations in the tails of their light curves, which can only be explained via some form of beaming. The fireball model for magnetar bursts has been used successfully to fit the phase-averaged light curves of the tails of giant flares, but so far no attempts have been made to fit the pulsations. We present a relatively simple numerical model to simulate beaming of magnetar flare emission. In our simulations, radiation escapes from the base of a fireball trapped in a dipolar magnetic field, and is scattered through the optically thick magnetosphere of the magnetar until it escapes. Beaming is provided by the presence of a relativistic outflow, as well as by the geometry of the system. We find that a simple picture for the relativistic outflow is enough to create the pulse fraction and sharp peaks observed in pulse profiles of magnetar flares, while without a relativistic outflow the beaming is insufficient to explain giant flare rotational modulations.
Beam transport and space charge compensation strategies (invited).
Meusel, O; Droba, M; Noll, D; Schulte, K; Schneider, P P; Wiesner, C
2016-02-01
The transport of intense ion beams is affected by the collective behavior of this kind of multi-particle and multi-species system. The space charge expressed by the generalized perveance dominates the dynamical process of thermalisation, which leads to emittance growth. To prevent changes of intrinsic beam properties and to reduce the intensity dependent focusing forces, space charge compensation seems to be an adequate solution. In the case of positively charged ion beams, electrons produced by residual gas ionization and secondary electrons provide the space charge compensation. The influence of the compensation particles on the beam transport and the local degree of space charge compensation is given by different beam properties as well as the ion beam optics. Especially for highly charged ion beams, space charge compensation in combination with poor vacuum conditions leads to recombination processes and therefore increased beam losses. Strategies for providing a compensation-electron reservoir at very low residual gas pressures will be discussed. PMID:26932109
Beam transport and space charge compensation strategies (invited)
NASA Astrophysics Data System (ADS)
Meusel, O.; Droba, M.; Noll, D.; Schulte, K.; Schneider, P. P.; Wiesner, C.
2016-02-01
The transport of intense ion beams is affected by the collective behavior of this kind of multi-particle and multi-species system. The space charge expressed by the generalized perveance dominates the dynamical process of thermalisation, which leads to emittance growth. To prevent changes of intrinsic beam properties and to reduce the intensity dependent focusing forces, space charge compensation seems to be an adequate solution. In the case of positively charged ion beams, electrons produced by residual gas ionization and secondary electrons provide the space charge compensation. The influence of the compensation particles on the beam transport and the local degree of space charge compensation is given by different beam properties as well as the ion beam optics. Especially for highly charged ion beams, space charge compensation in combination with poor vacuum conditions leads to recombination processes and therefore increased beam losses. Strategies for providing a compensation-electron reservoir at very low residual gas pressures will be discussed.
LATTICE/hor ellipsis/a beam transport program
Staples, J.
1987-06-01
LATTICE is a computer program that calculates the first order characteristics of synchrotrons and beam transport systems. The program uses matrix algebra to calculate the propagation of the betatron (Twiss) parameters along a beam line. The program draws on ideas from several older programs, notably Transport and Synch, adds many new ones and incorporates them into an interactive, user-friendly program. LATTICE will calculate the matched functions of a synchrotron lattice and display them in a number of ways, including a high resolution Tektronix graphics display. An optimizer is included to adjust selected element parameters so the beam meets a set of constraints. LATTICE is a first order program, but the effect of sextupoles on the chromaticity of a synchrotron lattice is included, and the optimizer will set the sextupole strengths for zero chromaticity. The program will also calculate the characteristics of beam transport systems. In this mode, the beam parameters, defined at the start of the transport line, are propagated through to the end. LATTICE has two distinct modes: the lattice mode which finds the matched functions of a synchrotron, and the transport mode which propagates a predefined beam through a beam line. However, each mode can be used for either type of problem: the transport mode may be used to calculate an insertion for a synchrotron lattice, and the lattice mode may be used to calculate the characteristics of a long periodic beam transport system.
Adaptive Vlasov Simulations of Intense Beams
Sonnendruecker, Eric; Gutnic, Michael; Haefele, Matthieu; Lemaire, Jean-Louis
2005-06-08
Most simulations of intense particle beams are performed nowadays using Particle In Cell (PIC) techniques. Direct grid based Vlasov methods have also been used but mostly for 1D simulations as they become very costly in higher dimensions when using uniform phase space grids. We have recently introduced adaptive mesh refinement techniques that allow us to automatically concentrate the grid points at places where the distribution function is varying most. In this paper we shall introduce this technique and show how it can be used to improve the efficiency of grid based Vlasov solvers.
An interactive beam position monitor system simulator
Ryan, W.A.; Shea, T.J.
1993-03-01
A system simulator has been implemented to aid the development of the RHIC position monitor system. Based on the LabVIEW software package by National Instruments, this simulator allows engineers and technicians to interactively explore the parameter space of a system during the design phase. Adjustable parameters are divided into three categories: beam, pickup, and electronics. The simulator uses these parameters in simple formulas to produce results in both time-domain and frequencydomain. During the prototyping phase, these simulated results can be compared to test data acquired with the same software package. The RHIC position monitor system is presented as an example, but the software is applicable to several other systems as well.
A reduced model for relativistic electron beam transport in solids and dense plasmas
NASA Astrophysics Data System (ADS)
Touati, M.; Feugeas, J.-L.; Nicolaï, Ph; Santos, J. J.; Gremillet, L.; Tikhonchuk, V. T.
2014-07-01
A hybrid reduced model for relativistic electron beam transport based on the angular moments of the relativistic kinetic equation with a special closure is presented. It takes into account collective effects with the self-generated electromagnetic fields as well as collisional effects with the slowing down of the relativistic electrons by plasmons, bound and free electrons and their angular scattering on both ions and electrons. This model allows for fast computations of relativistic electron beam transport while describing their energy distribution evolution. Despite the loss of information concerning the angular distribution of the electron beam, the model reproduces analytical estimates in the academic case of a monodirectional and monoenergetic electron beam propagating through a warm and dense plasma and hybrid particle-in-cell simulation results in a realistic laser-generated electron beam transport case.
Transport and Measurements of High-Current Electron Beams from X pinches
NASA Astrophysics Data System (ADS)
Agafonov, Alexey V.; Mingaleev, Albert R.; Romanova, Vera M.; Tarakanov, Vladimir P.; Shelkovenko, Tatiana A.; Pikuz, Sergey A.; Blesener, Isaac C.; Kusse, Bruce R.; Hammer, David A.
2009-01-01
Generation of electron beams is an unavoidable property of X-pinches and other pulsed-power-driven pinches of different geometry. Some issues concerning high-current electron beam transport from the X pinch to the diagnostic system and measurements of the beam current by Faraday cups with different geometry's are discussed. Of particular interest is the partially neutralized nature of the beam propagating from the X-pinch to a diagnostic system. Two scenarios of electron beam propagation from X-pinch to Faraday cup are analyzed by means of computer simulation using the PIC-code KARAT. The first is longitudinal neutralization by ions extracted from plasma at an output window of the X-pinch diode; the second is the beam transport through a plasma background between the diode and a diagnostic system.
Transport and Measurements of High-Current Electron Beams from X pinches
Agafonov, Alexey V.; Mingaleev, Albert R.; Romanova, Vera M.; Tarakanov, Vladimir P.; Shelkovenko, Tatiana A.; Pikuz, Sergey A.; Blesener, Isaac C.; Kusse, Bruce R.; Hammer, David A.
2009-01-21
Generation of electron beams is an unavoidable property of X-pinches and other pulsed-power-driven pinches of different geometry. Some issues concerning high-current electron beam transport from the X pinch to the diagnostic system and measurements of the beam current by Faraday cups with different geometry's are discussed. Of particular interest is the partially neutralized nature of the beam propagating from the X-pinch to a diagnostic system. Two scenarios of electron beam propagation from X-pinch to Faraday cup are analyzed by means of computer simulation using the PIC-code KARAT. The first is longitudinal neutralization by ions extracted from plasma at an output window of the X-pinch diode; the second is the beam transport through a plasma background between the diode and a diagnostic system.
Multisymplectic Integration for Beam and Plasma Simulations
NASA Astrophysics Data System (ADS)
Webb, Stephen; RadiaSoft, LLC Team
2015-11-01
Particle-in-cell methods are a standard tool for simulating charged particle systems such as fusion plasmas, intense beams, and laser- and beam-driven wakefield accelerators. Conventional methods have been successful in studying short-term dynamics, however numerical instabilities and artifacts such as grid heating make long-time simulations unreliable. A similar issue existed in single particle tracking for storage rings in the 1980s, which led to the development of symplectic algorithms. The essential insight that if the physical equations of motion derive from a least-action principle, then so too should the numerical equations of motion. The resulting update sequence preserves a symplectic 2-form, which is a strong constraint on the numerical solutions. The resulting algorithms are stable and accurate over very long simulation times. This same structure exists for field theories as well as single-particle dynamics. Such multisymplectic integrators have good stability properties and naturally encode conservation laws, making them ideal for simulations over many oscillations of the system. We present here a number of examples where multisymplectic algorithms have been used over very long time scales. This work was sponsored by the Air Force Office of Scientific Research, Young Investigator Program, under contract no. FA9550-15-C-0031. Distribution Statement A. Approved for public release; distribution is unlimited.
Designing a beam transport system for RHIC's electron lens
Gu, X.; Pikin, A.; Okamura, M.; Fischer, W.; Luo, Y.; Gupta, R.; Hock, J.; Raparia, D.
2011-03-28
We designed two electron lenses to apply head-on beam-beam compensation for RHIC; they will be installed near IP10. The electron-beam transport system is an important subsystem of the entire electron-lens system. Electrons are transported from the electron gun to the main solenoid and further to the collector. The system must allow for changes of the electron beam size inside the superconducting magnet, and for changes of the electron position by 5 mm in the horizontal- and vertical-planes.
Neoclassical electron transport in tokamaks with neutral-beam injection
Helander, P.; Akers, R.J.
2005-04-15
The collisional interaction between neutral-beam ions and bulk plasma electrons leads to convective transport of particles and energy similar to the well-known Ware pinch. These transport fluxes are calculated, and it is found that the particle flux is outward when the neutral beams are in the same direction as the plasma current and inward otherwise, while the opposite holds for the electron heat transport. This effectively shifts the neutral-beam fueling profile approximately one fast-ion banana width outward during coinjection and inward during counterinjection, and could help to explain why very different plasma behavior is sometimes observed when the direction of the plasma current is reversed.
Accurate Position Sensing of Defocused Beams Using Simulated Beam Templates
Awwal, A; Candy, J; Haynam, C; Widmayer, C; Bliss, E; Burkhart, S
2004-09-29
In position detection using matched filtering one is faced with the challenge of determining the best position in the presence of distortions such as defocus and diffraction noise. This work evaluates the performance of simulated defocused images as the template against the real defocused beam. It was found that an amplitude modulated phase-only filter is better equipped to deal with real defocused images that suffer from diffraction noise effects resulting in a textured spot intensity pattern. It is shown that the there is a tradeoff of performance dependent upon the type and size of the defocused image. A novel automated system was developed that can automatically select the right template type and size. Results of this automation for real defocused images are presented.
Simulations of Head-On Beam-Beam Compensation at RHIC and LHC
Valishev, A.; /Fermilab
2010-05-19
Electron lenses are proposed as a way to mitigate head-on beam-beam effects for RHIC and LHC upgrades. An extensive effort was put together within the US LARP in order to develop numerical simulations of beam-beam effects in the presence of electron lenses. In this report the results of numerical beam-beam simulations for RHIC and LHC are presented. The effect of electron lenses is demonstrated and sensitivity of beam-beam compensation to machine parameters is discussed.
Simulations of SSLV Ascent and Debris Transport
NASA Technical Reports Server (NTRS)
Rogers, Stuart; Aftosmis, Michael; Murman, Scott; Chan, William; Gomez, Ray; Gomez, Ray; Vicker, Darby; Stuart, Phil
2006-01-01
A viewgraph presentation on Computational Fluid Dynamic (CFD) Simulation of Space Shuttle Launch Vehicle (SSLV) ascent and debris transport analysis is shown. The topics include: 1) CFD simulations of the Space Shuttle Launch Vehicle ascent; 2) Debris transport analysis; 3) Debris aerodynamic modeling; and 4) Other applications.
Simulation study of LEBT for transversely coupled beam from an ECR ion source.
Yang, Y; Dou, W P; Sun, L T; Yao, Q G; Zhang, Z M; Yuan, Y J; He, Y; Zh, X Z; Zhao, H W
2016-02-01
A Low-Energy intense-highly charged ion Accelerator Facility (LEAF) program has been launched at Institute of Modern Physics. This accelerator facility consists of a superconducting Electron Cyclotron Resonance (ECR) ion source, a Low Energy Beam Transport (LEBT) system, and a Radio Frequency Quadrupole (RFQ). It is especially of interest for the extracted ion beam from the ECR ion source, which is transversely coupled, and this property will significantly affect the beam transmission in the LEBT line and the matching with the downstream RFQ. In the beam transport design of LEAF, beam decoupling in the LEBT is considered to lower down the projection emittances and the feasibility of the design has been verified by beam simulation with a transversely coupled beam from the ECR ion source. PMID:26932082
Simulation study of LEBT for transversely coupled beam from an ECR ion source
NASA Astrophysics Data System (ADS)
Yang, Y.; Dou, W. P.; Sun, L. T.; Yao, Q. G.; Zhang, Z. M.; Yuan, Y. J.; He, Y.; Zh, X. Z.; Zhao, H. W.
2016-02-01
A Low-Energy intense-highly charged ion Accelerator Facility (LEAF) program has been launched at Institute of Modern Physics. This accelerator facility consists of a superconducting Electron Cyclotron Resonance (ECR) ion source, a Low Energy Beam Transport (LEBT) system, and a Radio Frequency Quadrupole (RFQ). It is especially of interest for the extracted ion beam from the ECR ion source, which is transversely coupled, and this property will significantly affect the beam transmission in the LEBT line and the matching with the downstream RFQ. In the beam transport design of LEAF, beam decoupling in the LEBT is considered to lower down the projection emittances and the feasibility of the design has been verified by beam simulation with a transversely coupled beam from the ECR ion source.
Optimization of Electron Beam Transport for a 3-MeV DC Accelerator
NASA Astrophysics Data System (ADS)
Baruah, S.; Bhattacharjee, D.; Tiwari, R.; Sahu, G. K.; Thakur, K. B.; Mittal, K. C.; Gantayet, L. M.
2012-11-01
Transport of a low-current-density electron beam is simulated for an electrostatic accelerator system. Representative charged particles are uniformly assigned for emission from a circular indirectly-heated cathode of an axial electron gun. The beam is accelerated stepwise up to energy of 1 MeV electrostatically in a length-span of ~3 m using multiple accelerating electrodes in a column of ten tubes. The simulation is done under relativistic condition and the effect of the magnetic field induced by the cathode-heating filament current is taken into account. The beam diameter is tracked at different axial locations for various settings of the electrode potentials. Attempts have been made to examine and explain data on beam transport efficiency obtained from experimental observations.
Simulation of transverse combining of space-charge dominated beams
Celata, C.M.
1986-06-01
Rms emittance growth in the transverse plane due to the transverse combining of four identical elliptical beams of uniform density has been investigated. The emittance growth can be related by conservation of energy to the change in the electrostatic field energy. Its dependence on initial beam positions and radii has been calculated analytically for round beams and by computer simulation for elliptical beams.
Sonic simulation of the SPS power beam. Final report
Ott, J.H.; Rice, J.S.
1981-03-01
A Satellite Power System Microwave Transmission Simulator is described. The simulator generates and transmits a beam audible sound energy which is mathematically similar to the microwave beam which would transmit energy to Earth from a Solar Power Satellite. This allows areas such as power beam formation to be studied in a laboratory environment.
Nonlinear physics and energetic particle transport features of the beam-plasma instability
NASA Astrophysics Data System (ADS)
Carlevaro, Nakia; Falessi, Matteo V.; Montani, Giovanni; Zonca, Fulvio
2015-10-01
> In this paper we study transport features of a one-dimensional beam-plasma system in the presence of multiple resonances. As a model description of the general problem of a warm energetic particle beam, we assume cold supra-thermal beams and investigate the self-consistent evolution in the presence of the complete spectrum of nearly degenerate Langmuir modes. A qualitative transport estimation is obtained by computing the Lagrangian Coherent Structures of the system on given temporal scales. This leads to the splitting of the phase space into regions where the local transport processes are relatively faster. The general theoretical framework is applied to the case of the nonlinear dynamics of two cold beams, for which numerical simulation results are illustrated and analysed.
Research and development of H- ion source and low energy beam transport for a kaon-neutrino factory.
Ji, Q; Staples, J; Sy, A; Schenkel, T; Li, D
2012-02-01
A baseline H(-) ion source and low energy beam transport (LEBT) system have been identified for Project X. The filament-discharge H(-) ion source has been fabricated by D-Pace, Inc. and is now in operation at LBNL. The source is capable of delivering over 10 mA of H(-) beam in cw operation with normalized 4 rms emittances less than 0.7 π mm mrad. A two-solenoid magnetic lens LEBT system has been design. The design has been validated with simulations of beam transport for 5 mA 30 keV H(-) beams using various simulation codes. PMID:22380227
Experimental study of the longitudinal instability for beam transport
Reiser, M.; Wang, J.G.; Guo, W.M.; Wang, D.X.
1990-01-01
Theoretical model for beam longitudinal instability in a transport pipe with general wall impedance is considered. The result shows that a capacitive wall tends to stabilize the beam. The experimental study of the instability for a pure resistive-wall is presented, including the design parameters, setup and components for the experiment. 6 refs., 3 figs.
Fokker-Planck/Transport model for neutral beam driven tokamaks
Killeen, J.; Mirin, A.A.; McCoy, M.G.
1980-01-01
The application of nonlinear Fokker-Planck models to the study of beam-driven plasmas is briefly reviewed. This evolution of models has led to a Fokker-Planck/Transport (FPT) model for neutral-beam-driven Tokamaks, which is described in detail. The FPT code has been applied to the PLT, PDX, and TFTR Tokamaks, and some representative results are presented.
Spin transport in tilted electron vortex beams
NASA Astrophysics Data System (ADS)
Basu, Banasri; Chowdhury, Debashree
2014-12-01
In this paper we have enlightened the spin related issues of tilted Electron vortex beams. We have shown that in the skyrmionic model of electron we can have the spin Hall current considering the tilted type of electron vortex beam. We have considered the monopole charge of the tilted vortex as time dependent and through the time variation of the monopole charge we can explain the spin Hall effect of electron vortex beams. Besides, with an external magnetic field we can have a spin filter configuration.
Challenge of benchmarking simulation codes for the LANL beam-halo experiment.
Wangler, Thomas P.,; Lysenko, W. P.; Qiang, J.; Garnett, R. W.
2003-01-01
We compare macroparticle simulations with beam-profile measurements from a proton beam-halo experiment in a study of beam-halo formation in mismatched beams in a 52-quadrupole periodic-focusing channel. The lack of detailed measurement of the initial distribution is an important issue for being able to make reliable predictions of the halo. We have found earlier that different initial distributions with the same Courant-Snyder parameters and emittances produce similar matched-beam profiles, but different mismatched-beam profiles in the transport system. Also, input distributions with greater population in the tails produce larger rates of emittance growth. We have concluded that using only the known Courant-Snyder parameters and emittances as input parameters is insufficient information for reliable simulations of beam halo formed in mismatched beams. The question is how to obtain the best estimate of the input beam distribution needed for more accurate simulations. In this paper, we investigate a new least squares fitting procedure, which is applied to the simulations used to determine the injected beam distribution, in an attempt to obtain a more accurate description of halo formation than fiom simulation alone.
Quadrupole transport experiment with space charge dominated cesium ion beam
Faltens, A.; Keefe, D.; Kim, C.; Rosenblum, S.; Tiefenback, M.; Warwick, A.
1984-08-01
The purpose of the experiment is to investigate the beam current transport limit in a long quadrupole-focussed transport channel in the space charge dominated region where the space charge defocussing force is almost as large as the average focussing force of the channel.
Anderson, J.; Basten, M.A.; Rauth, L.; Booske, J.H.; Joe, J.; Scharer, J.E.
1995-12-31
Sheet electron beams and configurations with multiple electron beams have the potential to make possible higher power sources of microwave radiation due to their ability to transport high currents, at reduced current densities, through a single narrow RF interaction circuit. Possible microwave device applications using sheet electron beams include sheet-beam klystrons, grating TWT`s, and planar FELs. Historically, implementation of sheet beams in microwave devices has been discouraged by their susceptibility to the diocotron instability in solenoidal focusing systems. However, recent theoretical and numerical studies have shown that stable transport of sheet beams is possible in periodically cusped magnetic (PCM) fields. The use of an offset-pole PCM configuration has been shown analytically to provide side-fields for 2-D focusing of the beam, and this has been recently verified with PIC code simulations. The authors present further theoretical studies of sheet and multi-beam transport and discuss experimental measurements of an offset-pole PCM array which is currently being constructed.
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.
BEAM SIMULATIONS USING VIRTUAL DIAGNOSTICS FOR THE DRIVER LINAC
R. C. York; X. Wu; Q. Zhao
2011-12-21
End-to-end beam simulations for the driver linac have shown that the design meets the necessary performance requirements including having adequate transverse and longitudinal acceptances. However, to achieve reliable operational performance, the development of appropriate beam diagnostic systems and control room procedures are crucial. With limited R&D funding, beam simulations provide a cost effective tool to evaluate candidate beam diagnostic systems and to provide a critical basis for developing early commissioning and later operational activities. We propose to perform beam dynamic studies and engineering analyses to define the requisite diagnostic systems of the driver linac and through simulation to develop and test commissioning and operational procedures.
Neutralized transport of high intensity beams
Henestroza, E.; Yu, S.S.; Eylon, S.; Roy, P.K.; Anders, A.; Sharp, W.; Efthimion, P.; Gilson, E.; Welch, D.; Rose, D.
2003-05-01
The NTX experiment at the Heavy Ion Fusion Virtual National Laboratory is exploring the performance of neutralized final focus systems for high perveance heavy ion beams. A converging ion beam at the exit of the final focus magnetic system is injected into a neutralized drift section. The neutralization is provided by a metal arc source and an RF plasma source. Effects of a ''plasma plug'', where electrons are extracted from a localized plasma in the upstream end of the drift section, and are then dragged along by the ion potential, as well as the ''volumetric plasma'', where neutralization is provided by the plasma laid down along the ion path, are both studied and their relative effects on the beam spot size are compared. Comparisons with 3-D PIC code predictions will also be presented.
ITER Shape Controller and Transport Simulations
Casper, T A; Meyer, W H; Pearlstein, L D; Portone, A
2007-05-31
We currently use the CORSICA integrated modeling code for scenario studies for both the DIII-D and ITER experiments. In these simulations, free- or fixed-boundary equilibria are simultaneously converged with thermal evolution determined from transport models providing temperature and current density profiles. Using a combination of fixed boundary evolution followed by free-boundary calculation to determine the separatrix and coil currents. In the free-boundary calculation, we use the state-space controller representation with transport simulations to provide feedback modeling of shape, vertical stability and profile control. In addition to a tightly coupled calculation with simulator and controller imbedded inside CORSICA, we also use a remote procedure call interface to couple the CORSICA non-linear plasma simulations to the controller environments developed within the Mathworks Matlab/Simulink environment. We present transport simulations using full shape and vertical stability control with evolution of the temperature profiles to provide simulations of the ITER controller and plasma response.
Low-energy beam transport studies supporting the spallation neutron source 1-MW beam operation
Han, B. X.; Welton, R. F.; Murray, S. N. Jr.; Pennisi, T. R.; Santana, M.; Stockli, M. P.; Kalvas, T.; Tarvainen, O.
2012-02-15
The H{sup -} injector consisting of a cesium enhanced RF-driven ion source and a 2-lens electrostatic low-energy beam transport (LEBT) system supports the spallation neutron source 1 MW beam operation with {approx}38 mA beam current in the linac at 60 Hz with a pulse length of up to {approx}1.0 ms. In this work, two important issues associated with the low-energy beam transport are discussed: (1) inconsistent dependence of the post-radio frequency quadrupole accelerator beam current on the ion source tilt angle and (2) high power beam losses on the LEBT electrodes under some off-nominal conditions compromising their reliability.
Low-energy beam transport studies supporting the spallation neutron source 1-MW beam operation
Kalvas, T.; Welton, Robert F; Pennisi, Terry R
2012-01-01
The H{sup -} injector consisting of a cesium enhanced RF-driven ion source and a 2-lens electrostatic low-energy beam transport (LEBT) system supports the spallation neutron source 1 MW beam operation with {approx}38 mA beam current in the linac at 60 Hz with a pulse length of up to {approx}1.0 ms. In this work, two important issues associated with the low-energy beam transport are discussed: (1) inconsistent dependence of the post-radio frequency quadrupole accelerator beam current on the ion source tilt angle and (2) high power beam losses on the LEBT electrodes under some off-nominal conditions compromising their reliability.
Beam Transport in a Compact Dielectric Wall Accelerator for Proton Therapy
Chen, Y; Caporaso, G; Blackfield, D; Nelson, S D; Poole, B
2011-03-16
To attain the highest accelerating gradient in the compact dielectric wall (DWA) accelerator, the DWA will be operated in the 'virtual' traveling mode with potentially non-uniform and time-dependent axial accelerating field profiles, especially near the DWA entrance and exit, which makes beam transport challenging. We have established a baseline transport case without using any external lenses. Results of simulations using the 3-D, EM PIC code, LSP indicate that the DWA transport performance meets the medical specifications for proton treatment. Sensitivity of the transport performance to Blumlein block failure will be presented.
Particle trapping and beam transport issues in laser driven accelerators
NASA Astrophysics Data System (ADS)
Gwenael, Fubiani; Wim, Leemans; Eric, Esarey
2000-10-01
The LWFA and colliding pulses [1][2] sheme are capable of producing very compact electron bunches where the longitudinal size is much smaller than the transverse size. In this case, even if the electrons are relativistic, space charge force can affect the longitudinal and transverse bunch properties [3][4]. In the Self-modulated regime and the colliding pulse sheme, electrons are trapped from the background plasma and rapidly accelerated. We present theoretical studies of the generation and transport of electron bunches in LWFAs. The space charge effect induced in the bunch is modelled assuming the bunch is ellipsoid like. Beam transport in vacuum, comparison between gaussian and waterbag distribution, comparison between envelope model and PIC simulation will be discussed. This work is supported by the Director, Office of Science, Office of High Energy & Nuclear Physics, High Energy Physics Division, of the U.S Department of Energy, under Contract No. DE-AC03-76SF00098 [1]E.Esarey et al.,IEEE Trans. Plasma Sci. PS-24,252 (1996); W.P. Leemans et al, ibidem, 331. [2]D. Umstadter et al., Phys. Rev. Lett. 76, 2073 (1996); E.Esarey et al., Phys. Rev. Lett. 79, 2682 (1997); C.B Schroeder et al., Phys. Rev. E59, 6037 (1999) [3]DESY M87-161 (1987); DESY M88-013 (1988) [4] R.W. Garnett and T.P Wangler, IEEE Part. Acce. Conf. (1991)
High-Performance Beam Simulator for the LANSCE Linac
Pang, Xiaoying; Rybarcyk, Lawrence J.; Baily, Scott A.
2012-05-14
A high performance multiparticle tracking simulator is currently under development at Los Alamos. The heart of the simulator is based upon the beam dynamics simulation algorithms of the PARMILA code, but implemented in C++ on Graphics Processing Unit (GPU) hardware using NVIDIA's CUDA platform. Linac operating set points are provided to the simulator via the EPICS control system so that changes of the real time linac parameters are tracked and the simulation results updated automatically. This simulator will provide valuable insight into the beam dynamics along a linac in pseudo real-time, especially where direct measurements of the beam properties do not exist. Details regarding the approach, benefits and performance are presented.
Basten, M.A.; Booske, J.H.; Louis, L.J.; Joe, J.; Scharer, J.E.
1996-12-31
Sheet electron beams have the potential to make possible higher power sources of microwave radiation due to their ability to transport high currents, at reduced current densities, through a single narrow RF interaction circuit. The authors will discuss experimental investigations of the formation of an elliptical sheet beam using magnet quadrupoles and a round-beam electron gun. Features of this configuration include a low-cost, commercially available Pierce gun and a lens system consisting of four tunable magnetic quadrupoles with modest field gradients. Three-dimensional envelope and particle-in-cell simulations indicate that this method can generate highly elliptic output beams, with variability in final beam size, for laboratory experiments on sheet beam transport. They also will present the results of particle-in-cell simulations of the transport of sheet beams in long-period offset-pole periodic magnet arrays. While the stability of sheet beams in short-period arrays has previously been established, the extension to longer magnet periods indicate that side-focusing of space-charge dominated sheet beams is more problematic than beam stability. However, long-term (> 20 periods) stable transport is demonstrated for {lambda}{sub m} = 1 cm for a 2 A, 10 kV elliptical beam with a = 2.7 cm and b = 0.05 cm.
Beam Simulations for IRE and Driver-Status and Strategy
Friedman, A.; Grote, D.P.; Lee, E.P.; Sonnendrucker, E.
2000-03-01
The methods and codes employed in the U.S. Heavy Ion Fusion program to simulate the beams in an Integrated Research Experiments (IRE) facility and a fusion driver are presented in overview. A new family of models incorporating accelerating module impedance, multi-beam, and self-magnetic effects is described, and initial WARP3d particle simulations of beams using these models are presented. Finally, plans for streamlining the machine-design simulation sequence, and for simulating beam dynamics from the source to the target in a consistent and comprehensive manner, are described.
Oxygen transport properties estimation by DSMC-CT simulations
Bruno, Domenico; Frezzotti, Aldo; Ghiroldi, Gian Pietro
2014-12-09
Coupling DSMC simulations with classical trajectories calculations is emerging as a powerful tool to improve predictive capabilities of computational rarefied gas dynamics. The considerable increase of computational effort outlined in the early application of the method (Koura,1997) can be compensated by running simulations on massively parallel computers. In particular, GPU acceleration has been found quite effective in reducing computing time (Ferrigni,2012; Norman et al.,2013) of DSMC-CT simulations. The aim of the present work is to study rarefied Oxygen flows by modeling binary collisions through an accurate potential energy surface, obtained by molecular beams scattering (Aquilanti, et al.,1999). The accuracy of the method is assessed by calculating molecular Oxygen shear viscosity and heat conductivity following three different DSMC-CT simulation methods. In the first one, transport properties are obtained from DSMC-CT simulations of spontaneous fluctuation of an equilibrium state (Bruno et al, Phys. Fluids, 23, 093104, 2011). In the second method, the collision trajectory calculation is incorporated in a Monte Carlo integration procedure to evaluate the Taxman’s expressions for the transport properties of polyatomic gases (Taxman,1959). In the third, non-equilibrium zero and one-dimensional rarefied gas dynamic simulations are adopted and the transport properties are computed from the non-equilibrium fluxes of momentum and energy. The three methods provide close values of the transport properties, their estimated statistical error not exceeding 3%. The experimental values are slightly underestimated, the percentage deviation being, again, few percent.
Design and development of the HELL user station: beam transport, characterization, and shielding
NASA Astrophysics Data System (ADS)
Grittani, Gabriele Maria; Levato, Tadzio; Krus, Miroslav; Fasso, Alberto; Jeong, Tae Moon; Kim, Hyung Taek; Margarone, Daniele; Mocek, Tomáś; Precek, Martin; Versaci, Roberto; Korn, Georg
2015-05-01
In the framework of the ELI-Beamlines project, the HELL (High energy ELectron by Laser) platform will host an electron beamline with a dual aim: to explore innovative concepts of laser driven electron acceleration and to deliver a stable and reliable electron beam to external users, according to their specific needs. Because of this, it is crucial to identify the possible applications and their respective range of parameters. In order to accomplish this goal, Monte Carlo simulations of electron radiography and radiotherapy are performed and discussed. Once identified those parameter spaces, a beam transport line is studied and presented for each energy range. Finally, beam diagnostics are discussed.
Radiation Transport Calculations and Simulations
Fasso, Alberto; Ferrari, A.; /CERN
2011-06-30
This article is an introduction to the Monte Carlo method as used in particle transport. After a description at an elementary level of the mathematical basis of the method, the Boltzmann equation and its physical meaning are presented, followed by Monte Carlo integration and random sampling, and by a general description of the main aspects and components of a typical Monte Carlo particle transport code. In particular, the most common biasing techniques are described, as well as the concepts of estimator and detector. After a discussion of the different types of errors, the issue of Quality Assurance is briefly considered.
COMPARISON OF RF CAVITY TRANSPORT MODELS FOR BBU SIMULATIONS
Ilkyoung Shin,Byung Yunn,Todd Satogata,Shahid Ahmed
2011-03-01
The transverse focusing effect in RF cavities plays a considerable role in beam dynamics for low-energy beamline sections and can contribute to beam breakup (BBU) instability. The purpose of this analysis is to examine RF cavity models in simulation codes which will be used for BBU experiments at Jefferson Lab and improve BBU simulation results. We review two RF cavity models in the simulation codes elegant and TDBBU (a BBU simulation code developed at Jefferson Lab). elegant can include the Rosenzweig-Serafini (R-S) model for the RF focusing effect. Whereas TDBBU uses a model from the code TRANSPORT which considers the adiabatic damping effect, but not the RF focusing effect. Quantitative comparisons are discussed for the CEBAF beamline. We also compare the R-S model with the results from numerical simulations for a CEBAF-type 5-cell superconducting cavity to validate the use of the R-S model as an improved low-energy RF cavity transport model in TDBBU. We have implemented the R-S model in TDBBU. It will improve BBU simulation results to be more matched with analytic calculations and experimental results.
Kinetic transport simulation of energetic particles
NASA Astrophysics Data System (ADS)
Sheng, He; Waltz, R. E.
2016-05-01
A kinetic transport code (EPtran) is developed for the transport of the energetic particles (EPs). The EPtran code evolves the EP distribution function in radius, energy, and pitch angle phase space (r, E, λ) to steady state with classical slowing down, pitch angle scattering, as well as radial and energy transport of the injected EPs (neutral beam injection (NBI) or fusion alpha). The EPtran code is illustrated by treating the transport of NBI fast ions from high-n ITG/TEM micro-turbulence and EP driven unstable low-n Alfvén eigenmodes (AEs) in a well-studied DIII-D NBI heated discharge with significant AE central core loss. The kinetic transport code results for this discharge are compared with previous study using a simple EP density moment transport code ALPHA (R.E. Waltz and E.M. Bass 2014 Nucl. Fusion 54 104006). The dominant EP-AE transport is treated with a local stiff critical EP density (or equivalent pressure) gradient radial transport model modified to include energy-dependence and the nonlocal effects EP drift orbits. All previous EP transport models assume that the EP velocity space distribution function is not significantly distorted from the classical ‘no transport’ slowing down distribution. Important transport distortions away from the slowing down EP spectrum are illustrated by a focus on the coefficient of convection: EP energy flux divided by the product of EP average energy and EP particle flux.
Simulation of ion beam injection and extraction in an EBIS
NASA Astrophysics Data System (ADS)
Zhao, L.; Kim, J. S.
2016-02-01
An example simulation of Au+ charge breeding using FAR-TECH's integrated EBIS (electron beam ion source) modeling toolset is presented with the emphasis on ion beam injection and extraction. The trajectories of injected ions are calculated with PBGUNS (particle beam gun simulation) self-consistently by including the space charges from both ions and electrons. The ion beam, starting with initial conditions within the 100% acceptance of the electron beam, is then tracked by EBIS-PIC (particle-in-cell EBIS simulation code). In the trap, the evolution of the ion charge state distribution is estimated by charge state estimator. The extraction of charge bred ions is simulated with PBGUNS. The simulations of the ion injections show significant ion space charge effects on beam capture efficiency and the ionization efficiency.
Heavy ion beam transport and interaction with ICF targets
NASA Astrophysics Data System (ADS)
Velarde, G.; Aragonés, J. M.; Gago, J. A.; Gámez, L.; González, M. C.; Honrubia, J. J.; Martínez-Val, J. M.; Mínguez, E.; Ocaña, J. L.; Otero, R.; Perlado, J. M.; Santolaya, J. M.; Serrano, J. F.; Velarde, P. M.
1986-01-01
Numerical simulation codes provide an essential tool for analyzing the very broad range of concepts and variables considered in ICF targets. In this paper, the relevant processes embodied in the NORCLA code, needed to simulate ICF targets driven by heavy ion beams will be presented. Atomic physic models developed at DENIM to improve the atomic data needed for ion beam plasma interaction will be explained. Concerning the stopping power, the average ionization potential following a Thomas-Fermi model has been calculated, and results are compared with full quantum calculations. Finally, a parametric study of multilayered single shell targets driven by heavy ion beams will be shown.
Modeling of vapor transport of electron beam evaporation based coating system
NASA Astrophysics Data System (ADS)
Maiti, Namita; Tak, Atul; Khabade, Yashodhan; Suryawanshi, V. B.; Das, A. K.
2012-06-01
The modeling of vapor transport of an electron beam evaporation based coating system has been carried out in this work. Computational fluid dynamics (CFD) modeling has been tailored to analyze the evaporation and deposition of titanium material. Based on the physical model, the model relates the output power of the electron gun and the temperature profile on the evaporant surface. The simulated vapor distribution helps in predicting the coating thickness. The experimental results presented here agree with the simulation results.
Dust particle diffusion in ion beam transport region.
Miyamoto, N; Okajima, Y; Romero, C F; Kuwata, Y; Kasuya, T; Wada, M
2016-02-01
Dust particles of μm size produced by a monoplasmatron ion source are observed by a laser light scattering. The scattered light signal from an incident laser at 532 nm wavelength indicates when and where a particle passes through the ion beam transport region. As the result, dusts with the size more than 10 μm are found to be distributed in the center of the ion beam, while dusts with the size less than 10 μm size are distributed along the edge of the ion beam. Floating potential and electron temperature at beam transport region are measured by an electrostatic probe. This observation can be explained by a charge up model of the dust in the plasma boundary region. PMID:26932116
Dust particle diffusion in ion beam transport region
NASA Astrophysics Data System (ADS)
Miyamoto, N.; Okajima, Y.; Romero, C. F.; Kuwata, Y.; Kasuya, T.; Wada, M.
2016-02-01
Dust particles of μm size produced by a monoplasmatron ion source are observed by a laser light scattering. The scattered light signal from an incident laser at 532 nm wavelength indicates when and where a particle passes through the ion beam transport region. As the result, dusts with the size more than 10 μm are found to be distributed in the center of the ion beam, while dusts with the size less than 10 μm size are distributed along the edge of the ion beam. Floating potential and electron temperature at beam transport region are measured by an electrostatic probe. This observation can be explained by a charge up model of the dust in the plasma boundary region.
Generalized emittance measurements in a beam transport line
Skelly, J.; Gardner, C.; Luccio, A.; Kponou, A.; Reece, K.
1991-01-01
Motivated by the need to commission 3 beam transport lines for the new AGS Booster project, we have developed a generalized emittance-measurement program; beam line specifics are entirely resident in data tables, not in program code. For instrumentation, the program requires one or more multi-wire profile monitors; one or multiple profiles are acquired from each monitor, corresponding to one or multiple tunes of the transport line. Emittances and Twiss parameters are calculated using generalized algorithms. The required matix descriptions of the beam optics are constructed by an on-line general beam modeling program. Design of the program, its algorithms, and initial experience with it will be described. 4 refs., 2 figs., 1 tab.
Physics Design Considerations for Diagnostic X Beam Transport System
Chen, Y-J; Paul, A C
2000-08-01
Diagnostic X (D-X) transport system would extract the beam from the downstream transport line of the second axis of the Dual Axis Radiographic Hydrodynamic Test facility (DARHT-II[1]) and transport this beam to the D-X firing point via four branches of the beamline in order to provide four lines of sight for x-ray radiography. The design goal is to generate four DARHT-II-like x-ray pulses on each line of sight. In this paper, we discuss several potential beam quality degradation processes in the passive magnet lattice beamline and indicate how they constrain the D-X beamline design parameters, such as the background pressure, the pipe size, and the pipe material.
Three-Dimensional Perturbative Particle Simulation of Intense Ion Beams
NASA Astrophysics Data System (ADS)
Lee, W. Wei-Li; Stoltz, Peter H.; Davidson, Ronald C.; Qin, Hong
1998-11-01
A three-dimensional nonlinear perturbative (δ f) particle simulation scheme is under developement for studying the stability and transport properties of an intense ion beam propagating through background electrons and a periodic focusing lattice,(Q. Qian, W. Lee, and R. C. Davidson, Phys. Plasmas 4), 1915 (1997).^,(P. H. Stoltz, W. W. Lee, R. C. Davidson, this conference.) in which the distribution function is split into equilibrium and perturbed parts. To further facilitate the simulations, a mode expansion scheme (C. Z. Cheng and H. Okuda, J. Comp. Phys. 25), 133 (1977). for the perturbative scheme has been developed, in which only a few long wavelength modes along the direction of propagation are kept. The code will be useful for many applications in beam physics and is an intermediate step toward a fully three-dimensional multi-species code. The algorithm and its applications to the electron-proton instability (R. C. Davidson, P. H. Stoltz, W. W. Lee and T.-S. Wang, this conference.) in proton linacs and storage rings will be reported.
Simulations of beam-wire experiments at RHIC
Kim, Hyung Jin; Sen, Tanaji; /Fermilab
2007-06-01
A weak-strong beam simulation code (BBSIM) is used to study the compensation of long range beam-beam effects by current carrying wires at the Relativistic Heavy Ion Collider. Tune footprints and tune scans of diffusive aperture are presented for various wire separation distances. Beam life time is estimated using the dependence of the transverse diffusion coefficients on initial action. Comparison of the loss rate from tracking with that measured by BNL is presented.
Experimental studies and sheet beam transport for low-voltage, grating TWT amplifiers
Scharer, J.E.; Booske, J.H.; Joe, J.; Basten, M.A.; Anderson, J.; Wagner, K.
1995-12-31
Spontaneous emission and linear gain measurements for a low-voltage sheet-beam-compatible, grating TWT amplifier are presented. Results of analyses of a sheet beam formation by magnetic quadrupoles from a round beam and staple transport in a periodic cusp magnetic field are also discussed. A round ``probe`` beam from a 10 kV, 0.25 A Pierce gun electron source is utilized for 14 GHz amplifier experiments. The spontaneous emission measurements provide (a) measurement of the grating-induced spontaneous emission spectrum which can be correlated with the theoretically predicted linear gain curves, (b) measurements of broad-band noise emission, and (c) measurement of spontaneous emission in the backward-wave regime to correlate with start oscillation predictions. The noise emission spectra have been correlated with experimental factors including the guide magnetic field intensity and body current. Measurements of linear gain are also compared with the theoretical prediction in both forward and backward-wave regimes. A sheet beam can be formed by the use of magnetic quadrupoles to transform an initially round beam from a conventional Pierce gun into a highly eccentric elliptical beam. Results of a 3-D PIC simulation of the beam will be discussed. The authors will also discuss recent theoretical and numerical studies including PIC codes which show that stable transport of sheet beams is possible in periodically cusped magnetic (PCM) fields. The use of an offset-pole PCM configuration has been shown analytically to provide side-fields for 2-D focusing of the beam, and this is verified by PIC code simulations.
Design study of low-energy beam transport for multi-charge beams at RAON
NASA Astrophysics Data System (ADS)
Bahng, Jungbae; Qiang, Ji; Kim, Eun-San
2015-12-01
The Rare isotope Accelerator Of Newness (RAON) at the Rare Isotope Science Project (RISP) is being designed to simultaneously accelerate beams with multiple charge states. It includes a driver superconducting (SC) linac for producing 200 MeV/u and 400 kW continuous wave (CW) heavy ion beams from protons to uranium. The RAON consists of a few electron cyclotron resonance ion sources, a low-energy beam transport (LEBT) system, a CW 81.25 MHz, 500 keV/u radio frequency quadrupole (RFQ) accelerator, a medium-energy beam transport system, the SC linac, and a charge-stripper system. The LEBT system for the RISP accelerator facility consists of a high-voltage platform, two 90° dipoles, a multi-harmonic buncher (MHB), solenoids, electrostatic quadrupoles, a velocity equalizer, and a diagnostic system. The ECR ion sources are located on a high-voltage platform to reach an initial beam energy of 10 keV/u. After extraction, the ion beam is transported through the LEBT system to the RFQ accelerator. The generated charge states are selected by an achromatic bending system and then bunched by the MHB in the LEBT system. The MHB is used to achieve a small longitudinal emittance in the RFQ by generating a sawtooth wave with three harmonics. In this paper, we present the results and issues of the beam dynamics of the LEBT system.
TRANSIMS: Transportation analysis and simulation system
Smith, L.; Beckman, R.; Baggerly, K.
1995-07-01
This document summarizes the TRansportation ANalysis and SIMulation System (TRANSIMS) Project, the system`s major modules, and the project`s near-term plans. TRANSIMS will employ advanced computational and analytical techniques to create an integrated regional transportation systems analysis environment. The simulation environment will include a regional population of individual travelers and freight loads with travel activities and plans, whose individual interactions will be simulated on the transportation system, and whose environmental impact will be determined. We will develop an interim operational capability (IOC) for each major TRANSIMS module during the five-year program. When the IOC is ready, we will complete a specific case study to confirm the IOC features, applicability, and readiness.
TRANSIMS: TRansportation ANalysis and SIMulation System
Smith, L.; Beckman, R.; Anson, D.; Nagel, K.; Williams, M.
1995-08-01
This paper summarizes the TRansportation ANalysis and SIMulation System (TRANSIMS) Project, the system`s major modules, and the project`s near-term plans. TRANSIMS will employ advanced computational and analytical techniques to create an integrated regional transportation systems analysis environment. The simulation environment will include a regional population of individual travelers and freight loads with travel activities and plans, whose individual interactions will be simulated on the transportation system, and whose environmental impact will be determined. We will develop an interim operational capability (IOC) for each major TRANSIMS module during the five-year program. When the IOC is ready, we will complete a specific case study to confirm the IOC features, applicability, and readiness.
Beam-Beam Simulations for a Single Pass SuperB-Factory
Biagini, M.E.; Raimondi, P.; Seeman, J.; Schulte, D.; /CERN
2007-05-18
A study of beam-beam collisions for an asymmetric single pass SuperB-Factory is presented [1]. In this scheme an e{sup -} and an e{sup +} beam are first stored and damped in two Damping Rings (DR), then extracted, compressed and focused to the IP. After collision the two beams are re-injected in the DR to be damped and extracted for collision again. The explored beam parameters are similar to those used in the design of the International Linear Collider, except for the beam energies. Flat beams and round beams were compared in the simulations in order to optimize both luminosity performances and beam blowup after collision. With such approach a luminosity of the order of 10{sup 36} cm{sup -2} s{sup -1} can be achieved.
Documentation for TRACE: an interactive beam-transport code
Crandall, K.R.; Rusthoi, D.P.
1985-01-01
TRACE is an interactive, first-order, beam-dynamics computer program. TRACE includes space-charge forces and mathematical models for a number of beamline elements not commonly found in beam-transport codes, such as permanent-magnet quadrupoles, rf quadrupoles, rf gaps, accelerator columns, and accelerator tanks. TRACE provides an immediate graphic display of calculative results, has a powerful and easy-to-use command procedure, includes eight different types of beam-matching or -fitting capabilities, and contains its own internal HELP package. This report describes the models and equations used for each of the transport elements, the fitting procedures, and the space-charge/emittance calculations, and provides detailed instruction for using the code.
Simulations of high disruption colliding beams
Boyce, J.R.; Heifets, S.; Krafft, G.A.
1990-09-01
Recent B-factory proposals that use a linac beam colliding with the beam from a storage ring to achieve high luminosities (L > 10{sup 34} cm{sup {minus}2}sec{sup {minus}1}) result in very high disruption of the linac beam. The effects of such high disruption have been studied using the relativistic, 3-D code SWARM. We discuss the assumptions, parameters, and results of a series of runs that model such collisions. Regimes of high beam loss and methods to avoid them are also discussed. 5 refs., 4 figs.
Beam emittance measurements and simulations of injector line for radio frequency quadrupole.
Mathew, Jose V; Rao, S V L S; Pande, Rajni; Singh, P
2015-07-01
A 400 keV deuteron (D(+)) radio frequency quadrupole (RFQ) accelerator has been designed, built, and commissioned at the Bhabha Atomic Research Centre, India. A beam line has been developed for injecting deuterons into the 400 keV RFQ. This comprises of a RF plasma ion source and a low energy beam transport (LEBT) system, consisting of two solenoid magnets and two steerer magnets. The ion source is characterized in terms of transverse beam emittance. A slit-wire scanner based emittance measurement setup has been developed for the transverse emittance measurements of H(+) and D(+) beams. The measured emittance values are found to be well within the acceptance value for the RFQ. These measured emittance parameters are used to optimize the solenoid fields in LEBT to match the beam from the ion source to RFQ. TRACEWIN simulation code is used for the beam transport simulations. The simulations show 99% transmission of D(+) beam through the RFQ, while 95% transmission has been measured experimentally. PMID:26233371
Beam emittance measurements and simulations of injector line for radio frequency quadrupole
Mathew, Jose V. Rao, S. V. L. S.; Pande, Rajni; Singh, P.
2015-07-15
A 400 keV deuteron (D{sup +}) radio frequency quadrupole (RFQ) accelerator has been designed, built, and commissioned at the Bhabha Atomic Research Centre, India. A beam line has been developed for injecting deuterons into the 400 keV RFQ. This comprises of a RF plasma ion source and a low energy beam transport (LEBT) system, consisting of two solenoid magnets and two steerer magnets. The ion source is characterized in terms of transverse beam emittance. A slit-wire scanner based emittance measurement setup has been developed for the transverse emittance measurements of H{sup +} and D{sup +} beams. The measured emittance values are found to be well within the acceptance value for the RFQ. These measured emittance parameters are used to optimize the solenoid fields in LEBT to match the beam from the ion source to RFQ. TRACEWIN simulation code is used for the beam transport simulations. The simulations show 99% transmission of D{sup +} beam through the RFQ, while 95% transmission has been measured experimentally.
Beam simulation tools for GEANT4 (and neutrino source applications)
V.Daniel Elvira, Paul Lebrun and Panagiotis Spentzouris
2002-12-03
Geant4 is a tool kit developed by a collaboration of physicists and computer professionals in the High Energy Physics field for simulation of the passage of particles through matter. The motivation for the development of the Beam Tools is to extend the Geant4 applications to accelerator physics. Although there are many computer programs for beam physics simulations, Geant4 is ideal to model a beam going through material or a system with a beam line integrated to a complex detector. There are many examples in the current international High Energy Physics programs, such as studies related to a future Neutrino Factory, a Linear Collider, and a very Large Hadron Collider.
Murphy, T.J.
1986-11-01
In a recently proposed positron transport experiment, positrons would be deposited in a fusion plasma by forming a positronium (Ps) beam and passing it through the plasma. Positrons would be deposited as the beam is ionized by plasma ions and electrons. Radial transport of the positrons to the limiter could then be measured by detecting the gamma radiation produced by annihilation of positrons with electrons in the limiter. This would allow measurements of the transport of electron-mass particles and might shed some light on the mechanisms of electron transport in fusion plasmas. In this paper, the deposition and transport of positrons in a tokamak are simulated and the annihilation signal determined for several transport models. Calculations of the expected signals are necessary for the optimal design of a positron transport experiment. There are several mechanisms for the loss of positrons besides transport to the limiter. Annihilation with plasma electrons and reformation of positronium in positron-hydrogen collisions are two such processes. These processes can alter the signal and place restrictions ons on the plasma conditions in which positron transport experiments can be effectively performed.
Monoamine transporters: insights from molecular dynamics simulations
Grouleff, Julie; Ladefoged, Lucy Kate; Koldsø, Heidi; Schiøtt, Birgit
2015-01-01
The human monoamine transporters (MATs) facilitate the reuptake of the neurotransmitters serotonin, dopamine, and norepinephrine from the synaptic cleft. Imbalance in monoaminergic neurotransmission is linked to various diseases including major depression, attention deficit hyperactivity disorder, schizophrenia, and Parkinson’s disease. Inhibition of the MATs is thus an important strategy for treatment of such diseases. The MATs are sodium-coupled transport proteins belonging to the neurotransmitter/Na+ symporter (NSS) family, and the publication of the first high-resolution structure of a NSS family member, the bacterial leucine transporter LeuT, in 2005, proved to be a major stepping stone for understanding this family of transporters. Structural data allows for the use of computational methods to study the MATs, which in turn has led to a number of important discoveries. The process of substrate translocation across the membrane is an intrinsically dynamic process. Molecular dynamics simulations, which can provide atomistic details of molecular motion on ns to ms timescales, are therefore well-suited for studying transport processes. In this review, we outline how molecular dynamics simulations have provided insight into the large scale motions associated with transport of the neurotransmitters, as well as the presence of external and internal gates, the coupling between ion and substrate transport, and differences in the conformational changes induced by substrates and inhibitors. PMID:26528185
Monte Carlo beam capture and charge breeding simulation
Kim, J.S.; Liu, C.; Edgell, D.H.; Pardo, R.
2006-03-15
A full six-dimensional (6D) phase space Monte Carlo beam capture charge-breeding simulation code examines the beam capture processes of singly charged ion beams injected to an electron cyclotron resonance (ECR) charge breeder from entry to exit. The code traces injected beam ions in an ECR ion source (ECRIS) plasma including Coulomb collisions, ionization, and charge exchange. The background ECRIS plasma is modeled within the current frame work of the generalized ECR ion source model. A simple sample case of an oxygen background plasma with an injected Ar +1 ion beam produces lower charge breeding efficiencies than experimentally obtained. Possible reasons for discrepancies are discussed.
Corrêa da Silva, Thales M. Pakter, Renato; Rizzato, Felipe B.; Levin, Yan
2015-02-15
The effect of an initial envelope mismatch on the transport of bunched spherically symmetric beams is investigated. A particle-core model is used to estimate the maximum radius that halo particles can reach. The theory is used to obtain an empirical formula that provides the halo size as a function of system parameters. Taking into account, the incompressibility property of the Vlasov dynamics and the resulting Landau damping, an explicit form for the final stationary distribution attained by the beam is proposed. The distribution is fully self-consistent, presenting no free fitting parameters. The theory is used to predict the relevant beam transport properties, such as the final particle density distribution, the emittance growth, and the fraction of particles that will be expelled to form halo. The theoretical results are compared to the explicit N-particle dynamics simulations, showing a good agreement.
Beam Simulation Tools for GEANT4 (BT-V1.0). User's Guide
Elvira, V. Daniel; Lebrum, P.; Spentzouris, P.
2002-12-02
Geant4 is a tool kit developed by a collaboration of physicists and computer professionals in the high energy physics field for simulation of the passage of particles through matter. The motivation for the development of the Beam Tools is to extend the Geant4 applications to accelerator physics. The Beam Tools are a set of C++ classes designed to facilitate the simulation of accelerator elements: r.f. cavities, magnets, absorbers, etc. These elements are constructed from Geant4 solid volumes like boxes, tubes, trapezoids, or spheers. There are many computer programs for beam physics simulations, but Geant4 is ideal to model a beam through a material or to integrate a beam line with a complex detector. There are many such examples in the current international High Energy Physics programs. For instance, an essential part of the R&D associated with the Neutrino Source/Muon Collider accelerator is the ionization cooling channel, which is a section of the system aimed to reduce the size of the muon beam in phase space. The ionization cooling technique uses a combination of linacs and light absorbers to reduce the transverse momentum and size of the beam, while keeping the longitudinal momentum constant. The MuCool/MICE (muon cooling) experiments need accurate simulations of the beam transport through the cooling channel in addition to a detailed simulation of the detectors designed to measure the size of the beam. The accuracy of the models for physics processes associated with muon ionization and multiple scattering is critical in this type of applications. Another example is the simulation of the interaction region in future accelerators. The high luminosity and background environments expected in the Next Linear Collider (NLC) and the Very Large Hadron Collider (VLHC) pose great demand on the detectors, which may be optimized by means of a simulation of the detector-accelerator interface.
Parametric study of transport beam lines for electron beams accelerated by laser-plasma interaction
NASA Astrophysics Data System (ADS)
Scisciò, M.; Lancia, L.; Migliorati, M.; Mostacci, A.; Palumbo, L.; Papaphilippou, Y.; Antici, P.
2016-03-01
In the last decade, laser-plasma acceleration of high-energy electrons has attracted strong attention in different fields. Electrons with maximum energies in the GeV range can be laser-accelerated within a few cm using multi-hundreds terawatt (TW) lasers, yielding to very high beam currents at the source (electron bunches with up to tens-hundreds of pC in a few fs). While initially the challenge was to increase the maximum achievable electron energy, today strong effort is put in the control and usability of these laser-generated beams that still lack of some features in order to be used for applications where currently conventional, radio-frequency (RF) based, electron beam lines represent the most common and efficient solution. Several improvements have been suggested for this purpose, some of them acting directly on the plasma source, some using beam shaping tools located downstream. Concerning the latter, several studies have suggested the use of conventional accelerator magnetic devices (such as quadrupoles and solenoids) as an easy implementable solution when the laser-plasma accelerated beam requires optimization. In this paper, we report on a parametric study related to the transport of electron beams accelerated by laser-plasma interaction, using conventional accelerator elements and tools. We focus on both, high energy electron beams in the GeV range, as produced on petawatt (PW) class laser systems, and on lower energy electron beams in the hundreds of MeV range, as nowadays routinely obtained on commercially available multi-hundred TW laser systems. For both scenarios, our study allows understanding what are the crucial parameters that enable laser-plasma accelerators to compete with conventional ones and allow for a beam transport. We show that suitable working points require a tradeoff-combination between low beam divergence and narrow energy spread.
Simulations of the LEDA LEBT H{sup +} beam
Smith, H.V. Jr.; Sherman, J.D.; Stevens, R.R. Jr.; Young, L.M.
1997-08-01
The computer codes TRACE and SCHAR model the Low-Energy Demonstration Accelerator (LEDA) Low-Energy Beam Transport (LEBT) for 75-keV, 110-mA, dc H{sup +} beams. Solenoid-lens location studies verify that the proposed LEBT design gives a near-optimum match to the LEDA RFQ. The desired RFQ transmission ({ge} 90%) and output emittance ({le} 0.22 {pi} mm mrad, transverse) are obtained when PARMTEQM transports the file for the SCHAR-generated optimum beam through the RFQ.
Atomic oxygen beam source for erosion simulation
NASA Technical Reports Server (NTRS)
Cuthbertson, J. W.; Langer, W. D.; Motley, R. W.; Vaughn, J. A.
1991-01-01
A device for the production of low energy (3 to 10 eV) neutral atomic beams for surface modification studies is described that reproduces the flux of atomic oxygen in low Earth orbit. The beam is produced by the acceleration of plasma ions onto a negatively biased plate of high-Z metal; the ions are neutralized and reflected by the surface, retaining some fraction of their incident kinetic energy, forming a beam of atoms. The plasma is generated by a coaxial RF exciter which produces a magnetically-confined (4 kG) plasma column. At the end of the column, ions fall through the sheath to the plate, whose bias relative to the plasma can be varied to adjust the beam energy. The source provides a neutral flux approximately equal to 5 x 10(exp 16)/sq cm at a distance of 9 cm and a fluence approximately equal to 10(exp 20)/sq cm in five hours. The composition and energy of inert gas beams was diagnosed using a mass spectometer/energy analyzer. The energy spectra of the beams demonstrate energies in the range 5 to 15 eV, and qualitatively show expected dependences upon incident and reflecting atom species and potential drop. Samples of carbon film, carbon-based paint, Kapton, mylar, and teflon exposed to atomic O beams show erosion quite similar to that observed in orbit on the space shuttle.
Monte Carlo simulations of nanoscale focused neon ion beam sputtering.
Timilsina, Rajendra; Rack, Philip D
2013-12-13
A Monte Carlo simulation is developed to model the physical sputtering of aluminum and tungsten emulating nanoscale focused helium and neon ion beam etching from the gas field ion microscope. Neon beams with different beam energies (0.5-30 keV) and a constant beam diameter (Gaussian with full-width-at-half-maximum of 1 nm) were simulated to elucidate the nanostructure evolution during the physical sputtering of nanoscale high aspect ratio features. The aspect ratio and sputter yield vary with the ion species and beam energy for a constant beam diameter and are related to the distribution of the nuclear energy loss. Neon ions have a larger sputter yield than the helium ions due to their larger mass and consequently larger nuclear energy loss relative to helium. Quantitative information such as the sputtering yields, the energy-dependent aspect ratios and resolution-limiting effects are discussed. PMID:24231648
Weak-strong simulation on head-on beam-beam compensation in the RHIC
Luo,Y.; Fischer, W.; McIntosh, E.; Robert-Demolaize, G.; Abreu, N.; Beebe-Wang, J.; Montag, C.
2009-05-04
In the Relativistic Heavy Ion Collider (RHIC) beams collide in the two interaction points IP6 and IP8. To further increase the bunch intensity above 2 x 10{sup 11} or further reduce the transverse emittance in polarized proton operation, there will not be enough tune space between the current working area [2/3, 7/10] to hold the beam-beam generated tune spread. We proposed a low energy DC electron beam (e-lens) with similar Gaussian transverse profiles to collide with the proton beam at IP10. Early studies have shown that e-lens does reduce the proton-proton beam-beam tune spread. In this article, we carried out numerical simulation to investigate the effects of the head-on beam-beam effect on the proton's colliding beam lifetime and emittance growth. The preliminary results including scans of compensation strength, phase advances between IP8 and IP10, electron beam transverse sizes are presented. In these studies, the particle loss in the multi-particle simulation is used for the comparison between different conditions.
Physics Design Considerations for Diagnostic X Electron Beam Transport System
Chen, Y-J
2000-04-10
The Diagnostic X (D-X) beamlines will transport the DARHT-II beam from the end of the accelerator to the Diagnostic X firing point providing four lines of sight for x-ray radiography. The design goal for the Diagnostic X beamline is to deliver four x-ray pulses with the DARHT-II dose format and time integrated spot size on each line of sight. The D-X beamline's final focus should be compatible with a range of first conjugates from 1 m-5 m. Furthermore, the D-X beamline operational parameters and the beamline layout should not preclude a possible upgrade to additional lines of sight. The DARHT-II accelerator is designed to deliver beams at a rate of 1 pulse per minute or less. Tuning the D-X beamline with several hundred optical elements would be time consuming. Therefore, minimizing the required number of tuning shots for the D-X beamline is also an important design goal. Many different beamline configurations may be able to accomplish these design objectives, and high beam quality (i.e., high current and low emittance) must be maintained throughout the chosen beamline configuration in order to achieve the DARHT-II x-ray dose format. In general, the longer the distance a beam travels, the harder it is to preserve the beam quality. Therefore, from the point of view of maintaining beam quality, it is highly desirable to minimize the beamline length. Lastly, modification to the DARHT-II building and the downstream transport should be minimized. Several processes can degrade beam quality by increasing the beam emittance, increasing the time-varying transverse beam motion, creating a beam halo, or creating a time-varying beam envelope. In this report, we consider those processes in the passive magnet lattice beamline and indicate how they constrain the beamline design. The physics design considerations for the active components such as the kicker system will be discussed in Ref. 2. In Sec. I, we discuss how beam emittance affects the x-ray forward dose. We also
Gyrokinetic particle simulation of neoclassical transport
Lin, Z.; Tang, W.M.; Lee, W.W.
1995-02-01
A time varying weighting ({delta} f) scheme for gyrokinetic particle simulation is applied to a steady state, multi-species simulation of neoclassical transport. Accurate collision operators conserving momentum and energy are developed and implemented. Simulation results using these operators are found to agree very well with neoclassical theory. For example, it is dynamically demonstrated in these multispecies simulations that like-particle collisions produce no particle flux and that the neoclassical fluxes are ambipolar for an ion-electron plasma. An important physics feature of the present scheme is the introduction of toroidal sheared flow to the simulations. Simulation results are in agreement with the existing analytical neoclassical theory of Hinton and Wong. The poloidal electric field associated with toroidal mass flow is found to enhance density gradient driven electron particle flux and the bootstrap current while reducing temperature gradient driven flux and current. Finally, neoclassical theory in steep gradient profile relevant to the edge regime is examined by taking into account finite banana width effects. In general, the present work demonstrates a valuable new capability for studying important aspects of neoclassical transport inaccessible by conventional analytical calculation processes.
Atomic oxygen beam source for erosion simulation
NASA Technical Reports Server (NTRS)
Cuthbertson, J. W.; Langer, W. D.; Motley, R. W.
1990-01-01
A device for production of low-energy (5-10 eV) neutral atomic beams for surface modification studies, which recreates the flux of atomic oxygen in LEO, is described. The beam is produced by acceleration of plasma ions onto a negatively biased plate of high-Z metal; the ions are neutralized and reflected by the surface, retaining a large fraction of their incident kinetic energy, forming a beam of atoms. The device is based on a magnetically confined (3-4 kG) coaxial plasma source and the atom energy can be varied by adjusting the bias voltage. The source provides a neutral flux of roughly 5 x 10 to the 16th/sq cm/s at a distance of 10 cm and a fluence of roughly 10 to the 21st/sq cm in five hours. The source has been characterized with plasma diagnostics and by measuring the energy of an atomic argon beam using a mass spectrometer. Samples of carbon film, carbon-based paint, Kapton, Mylar, and Teflon exposed to atomic O beams show erosion quite similar to those observed in orbit on the Space Shuttle.
Numerical simulation of ion charge breeding in electron beam ion source
Zhao, L. Kim, Jin-Soo
2014-02-15
The Electron Beam Ion Source particle-in-cell code (EBIS-PIC) tracks ions in an EBIS electron beam while updating electric potential self-consistently and atomic processes by the Monte Carlo method. Recent improvements to the code are reported in this paper. The ionization module has been improved by using experimental ionization energies and shell effects. The acceptance of injected ions and the emittance of extracted ion beam are calculated by extending EBIS-PIC to the beam line transport region. An EBIS-PIC simulation is performed for a Cs charge-breeding experiment at BNL. The charge state distribution agrees well with experiments, and additional simulation results of radial profiles and velocity space distributions of the trapped ions are presented.
Low energy beam transport in the NSLS UV-FEL
Zhang, X.; Gallardo, J.C.
1993-06-01
A design of the injection low energy transport line for the proposed NSLS UV-FEL is presented. The main concern is to control the beam transverse emittance dilution due to space charge, energy spread and non-linear forces introduced by magnetic elements. The design considerations to optimize the transport line are discussed including the deleterious effects of space charge and energy spread as modeled by the particle code PARMELA. The results from PARMELA are analyzed, and the concept of slice emittance is used to examine the causes of emittance growth.
Low energy beam transport in the NSLS UV-FEL
Zhang, X.; Gallardo, J.C.
1993-01-01
A design of the injection low energy transport line for the proposed NSLS UV-FEL is presented. The main concern is to control the beam transverse emittance dilution due to space charge, energy spread and non-linear forces introduced by magnetic elements. The design considerations to optimize the transport line are discussed including the deleterious effects of space charge and energy spread as modeled by the particle code PARMELA. The results from PARMELA are analyzed, and the concept of slice emittance is used to examine the causes of emittance growth.
Plasma neutralization models for intense ion beam transport in plasma
Kaganovich, Igor D.; Startsev, Edward A.; Davidson, Ronald C.; O'Rourke, Sean; Lee, Edward P.
2003-05-01
Plasma neutralization of an intense ion pulse is of interest for many applications, including plasma lenses, heavy ion fusion, cosmic ray propagation, etc. An analytical electron fluid model has been developed based on the assumption of long charge bunches (l{sub b} >> r{sub b}). Theoretical predictions are compared with the results of calculations utilizing a particle-in-cell (PIC) code. The cold electron fluid results agree well with the PIC simulations for ion beam propagation through a background plasma. The analytical predictions for the degree of ion beam charge and current neutralization also agree well with the results of the numerical simulations. The model predicts very good charge neutralization (>99%) during quasi-steady-state propagation, provided the beam pulse duration {tau}{sub b} is much longer than the electron plasma period 2{pi}/{omega}{sub p}, where {omega}{sub p} = (4{pi}e{sup 2}n{sub p}/m){sup 1/2} is the electron plasma frequency, and n{sub p} is the background plasma density. In the opposite limit, the beam pulse excites large-amplitude plasma waves. The analytical formulas derived in this paper can provide an important benchmark for numerical codes, and provide scaling relations for different beam and plasma parameters.
Optics and beam transport in energy recovery linacs
NASA Astrophysics Data System (ADS)
Hoffstaetter, Georg H.; Litvinenko, Vladimir; Owen, Hywel
2006-02-01
Here, we report on the working group "Optics and Beam Transport" of the 2005 Energy-Recovery-Linac Workshop. This workshop also had working groups on "Electron Guns and Injector Designs", "Superconducting RF and RF Control", and "Synchronization and Diagnostics/Instrumentation". Here, we are concerned with the many different ERL proposals that international laboratories have been working on. Subjects of concern are optics, accelerator design and modeling, stability requirements, designs of the merger that connects the conventional injector linac with the Energy Recovery Linac, longitudinal phase space manipulations to produce short pulses, beam dynamics and limitations by beam instabilities, and computational aspects of space-charge and synchrotron radiation effects. A coarse grain overview is given and reference is made to more detailed articles that were presented in this working group. Subjects are identified where collaborations should be encouraged and areas of future R&D are prioritized.
Electron beam transport for the LBL IR-FEL
Staples, J.; Edighoffer, J.; Kim, Kwang-Je
1992-07-01
The infrared flee-electron laser (IR-FEL) proposed by LBL as part of the Combustion Dynamics Research Laboratory (CDRL) consists of a multiple-pass accelerator with superconducting cavities supplying a 55 MeV 12 mA beam to an undulator within a 24-meter optical cavity. Future options include deceleration through the same cavities for energy recovery and reducing the power in the beam dump. The electron transport system from the injector through the cavities and undulator must satisfy conditions of high order achromaticity, isochronicity, unity first-order transport matrix around the recirculation loop, variable betatron match into the undulator, ease of operation and economical implementation. This paper presents a workable solution that satisfies these requirements.
A Hardware transverse beam frequency response simulator
Ning, J.; Tan, C.Y.; /Fermilab
2005-05-01
We built an electronic instrument that can mimic the transverse beam frequency response. The instrument consists of (1) a time delay circuit with an analog-to-digital converter (ADC) which contains a first-in-first-out random assess memory (FIFO RAM) and a digital-to-analog converter (DAC); (2) a variable phase shifter circuit which is based on an all pass filter with a bandwidth of 25kHz to 30kHz and (3) a commutating filter which is a nonlinear band pass filter. With this instrument, we can dynamically adjust the betatron tune, the synchrotron tune, and the chromaticity. Using this instrument, we are able to test other beam systems without using actual beam.
Periodic Poisson model for beam dynamics simulation
NASA Astrophysics Data System (ADS)
Dohlus, M.; Henning, Ch.
2016-03-01
A method is described to solve the Poisson problem for a three dimensional source distribution that is periodic into one direction. Perpendicular to the direction of periodicity a free space (or open) boundary condition is realized. In beam physics, this approach allows us to calculate the space charge field of a continualized charged particle distribution with periodic pattern. The method is based on a particle-mesh approach with equidistant grid and fast convolution with a Green's function. The periodic approach uses only one period of the source distribution, but a periodic extension of the Green's function. The approach is numerically efficient and allows the investigation of periodic- and pseudoperiodic structures with period lengths that are small compared to the source dimensions, for instance of laser modulated beams or of the evolution of micro bunch structures. Applications for laser modulated beams are given.
Simulation of Weibel Instability for LWFA and PWFA Electron Beams
Allen, B.; Muggli, P.; Feng, B.; Katsouleas, T.; Huang, C.; Yakimenko, V.; Maksimchuk, A.
2009-01-22
Weibel instability is of central importance for relativistic beams both in laboratory, ex. fast-igniter concept for inertial confinement fusion, and astrophysical, ex. cosmic jets, plasmas. Simulations, using QuickPIC, of an intense and monoenergetic beam propagating through a plasma were conducted for experimental setups with Laser Wakefield and RF accelerators and show the appearance of Weibel instability (or current instability). The appearance of the instability is investigated as a function of beam parameters (density, spot size and bunch length) and plasma parameters (plasma density and length of plasma). We present preliminary simulation results that show that the instability should be observable for the RF accelerator experiment.
Three-dimensional particle simulation of heavy-ion fusion beams*
NASA Astrophysics Data System (ADS)
Friedman, Alex; Grote, David P.; Haber, Irving
1992-07-01
The beams in a heavy-ion-beam-driven inertial fusion (HIF) accelerator are collisionless, nonneutral plasmas, confined by applied magnetic and electric fields. These space-charge-dominated beams must be focused onto small (few mm) spots at the fusion target, and so preservation of a small emittance is crucial. The nonlinear beam self-fields can lead to emittance growth, and so a self-consistent field description is needed. To this end, a multidimensional particle simulation code, warp [Friedman et al., Part. Accel. 37-38, 131 (1992)], has been developed and is being used to study the transport of HIF beams. The code's three-dimensional (3-D) package combines features of an accelerator code and a particle-in-cell plasma simulation. Novel techniques allow it to follow beams through many accelerator elements over long distances and around bends. This paper first outlines the algorithms employed in warp. A number of applications and corresponding results are then presented. These applications include studies of: beam drift-compression in a misaligned lattice of quadrupole focusing magnets; beam equilibria, and the approach to equilibrium; and the MBE-4 experiment [AIP Conference Proceedings 152 (AIP, New York, 1986), p. 145] recently concluded at Lawrence Berkeley Laboratory (LBL). Finally, 3-D simulations of bent-beam dynamics relevant to the planned Induction Linac Systems Experiments (ILSE) [Fessenden, Nucl. Instrum. Methods Plasma Res. A 278, 13 (1989)] at LBL are described. Axially cold beams are observed to exhibit little or no root-mean-square emittance growth at midpulse in transiting a (sharp) bend. Axially hot beams, in contrast, do exhibit some emittance growth.
Self-amplified spontaneous emission free electron laser devices and nonideal electron beam transport
NASA Astrophysics Data System (ADS)
Lazzarino, L. L.; Di Palma, E.; Anania, M. P.; Artioli, M.; Bacci, A.; Bellaveglia, M.; Chiadroni, E.; Cianchi, A.; Ciocci, F.; Dattoli, G.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M.; Gatti, G.; Giannessi, L.; Mostacci, A.; Musumeci, P.; Petralia, A.; Petrillo, V.; Pompili, R.; Rau, J. V.; Rossi, A. R.; Sabia, E.; Vaccarezza, C.; Villa, F.
2014-11-01
We have developed, at the SPARC test facility, a procedure for a real time self-amplified spontaneous emission free electron laser (FEL) device performance control. We describe an actual FEL, including electron and optical beam transport, through a set of analytical formulas, allowing a fast and reliable on-line "simulation" of the experiment. The system is designed in such a way that the characteristics of the transport elements and the laser intensity are measured and adjusted, via a real time computation, during the experimental run, to obtain an on-line feedback of the laser performances. The detail of the procedure and the relevant experimental results are discussed.
Particle Simulations of a Long Pulse Electron Beam in a Bend
Poole, B.R.; Chen, Y.J.
2000-08-15
Advanced x-ray radiography machines require that multiple electron beam pulses be delivered to x-ray converter targets over several lines of sight. This can be accomplished using a single accelerator by using a fast kicker to deliver the electron beam pulses to several beamlines. This type of radiography machine requires transport lines with several large achromatic bends in the individual transport lines. To maintain a small spot size and a large dose for an x-ray pulse created at the converter target at each transport line requires that emittance growth be kept to a minimum on each beamline. Emittance growth can arise from nonlinear forces associated with the external focusing elements, nonlinear image forces, and non-linear space charge fields associated with the curvature of the beam and the transport line. We have used a multi-slice, particle-in-cell code to study the emittance growth in a bend. The code uses the beam slice's local coordinates. Typically, the radius of curvature, R for such a beam and the transport line is much larger than the pipe radius, b. The space charge fields can be approximated as that in a straight beam with correction terms to first order in b/R. To include the effects of the bend geometry on the space charge fields, these correction terms are implemented in the code. The relative importance of emittance growth due to nonlinear image forces associated with envelope oscillations of a non-round beam in the bend and due to nonlinear space charge fields associated with the bend geometry will be quantified. Simulation results for the baseline design orbit as well as off-energy transport will be presented.
Gyrokinetic particle simulation of neoclassical transport
Lin, Z.; Tang, W.M.; Lee, W.W.
1995-08-01
A time varying weighting ({delta}{ital f} ) scheme for gyrokinetic particle simulation is applied to a steady-state, multispecies simulation of neoclassical transport. Accurate collision operators conserving momentum and energy are developed and implemented. Simulation results using these operators are found to agree very well with neoclassical theory. For example, it is dynamically demonstrated that like-particle collisions produce no particle flux and that the neoclassical fluxes are ambipolar for an ion--electron plasma. An important physics feature of the present scheme is the introduction of toroidal flow to the simulations. Simulation results are in agreement with the existing analytical neoclassical theory. The poloidal electric field associated with toroidal mass flow is found to enhance density gradient-driven electron particle flux and the bootstrap current while reducing temperature gradient-driven flux and current. Finally, neoclassical theory in steep gradient profile relevant to the edge regime is examined by taking into account finite banana width effects. In general, in the present work a valuable new capability for studying important aspects of neoclassical transport inaccessible by conventional analytical calculation processes is demonstrated. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.
Monte Carlo simulation for the transport beamline
Romano, F.; Cuttone, G.; Jia, S. B.; Varisano, A.; Attili, A.; Marchetto, F.; Russo, G.; Cirrone, G. A. P.; Schillaci, F.; Scuderi, V.; Carpinelli, M.
2013-07-26
In the framework of the ELIMED project, Monte Carlo (MC) simulations are widely used to study the physical transport of charged particles generated by laser-target interactions and to preliminarily evaluate fluence and dose distributions. An energy selection system and the experimental setup for the TARANIS laser facility in Belfast (UK) have been already simulated with the GEANT4 (GEometry ANd Tracking) MC toolkit. Preliminary results are reported here. Future developments are planned to implement a MC based 3D treatment planning in order to optimize shots number and dose delivery.
Transport studies of LPA electron beam towards the FEL amplification at COXINEL
NASA Astrophysics Data System (ADS)
Khojoyan, M.; Briquez, F.; Labat, M.; Loulergue, A.; Marcouillé, O.; Marteau, F.; Sharma, G.; Couprie, M. E.
2016-09-01
Laser Plasma Acceleration (LPA) [1] is an emerging concept enabling to generate electron beams with high energy, high peak current and small transverse emittance within a very short distance. The use of LPA can be applied to the Free Electron Laser (FEL) [2] case in order to investigate whether it is suitable for the light amplification in the undulator. However, capturing and guiding of such beams to the undulator is very challenging, because of the large divergence and high energy spread of the electron beams at the plasma exit, leading to large chromatic emittances. A specific beam manipulation scheme was recently proposed for the COXINEL (Coherent X-ray source inferred from electrons accelerated by laser) setup, which makes an advantage from the intrinsically large chromatic emittance of such beams [3]. The electron beam transport is studied using two simulation codes: a SOLEIL in-house one and ASTRA [4]. The influence of the collective effects on the electron beam performance is also examined.
Winklehner, D.; Leitner, D. Cole, D.; Machicoane, G.; Tobos, L.
2014-02-15
In this paper we describe the first systematic measurement of beam neutralization (space charge compensation) in the ECR low energy transport line with a retarding field analyzer, which can be used to measure the potential of the beam. Expected trends for the space charge compensation levels such as increase with residual gas pressure, beam current, and beam density could be observed. However, the overall levels of neutralization are consistently low (<60%). The results and the processes involved for neutralizing ion beams are discussed for conditions typical for ECR injector beam lines. The results are compared to a simple theoretical beam plasma model as well as simulations.
Global gyrokinetic simulation of tokamak transport
Furnish, G.; Horton, W.; Kishimoto, Y.; LeBrun, M.J.; Tajima, T. |
1998-10-01
A kinetic simulation code based on the gyrokinetic ion dynamics in global general metric (including a tokamak with circular or noncircular cross-section) has been developed. This gyrokinetic simulation is capable of examining the global and semi-global driftwave structures and their associated transport in a tokamak plasma. The authors investigate the property of the ion temperature gradient (ITG) or {eta}{sub i}({eta}{sub i} {equivalent_to} {partial_derivative}{ell}nT{sub i}/{partial_derivative}{ell}n n{sub i}) driven drift waves in a tokamak plasma. The emergent semi-global drift wave modes give rise to thermal transport characterized by the Bohm scaling.
Particle simulation of transport in fusion devices
Procassini, R.J.; Birdsall, C.K.; Morse, E.C. . Electronics Research Lab.); Cohen, B.I. )
1989-10-17
Our research in the area of transport processes in fusion devices has recently been centered on the development of particle simulation models of transport in the scrape-off layer (SOL) of a diverted tokamak. As part of this research, we have been involved in the development of a suitable boundary condition for the plasma current at a floating plate that allows use of long time- and space-scale implicit simulation techniques. We have also been involved in a comparison of results from our particle-in-cell (PIC) code and a bounce-averaged Fokker-Planck (FP) code for the study of particle confinement in an auxiliary heated mirror plasma. 3 refs., 1 fig.
Wang, Jian-Guang; Zhang, Yan
2011-01-01
A Medium-Energy Beam Transport (MEBT) line is employed in the SNS linac to match the beam from an RFQ to a DTL and to perform other functions. The MEBT lattice consists of fourteen electromagnetic quadrupoles and other devices. The quads have very small aspect ratios (steel length over aperture diameter), and they are densely packed in the lattice. Significant fringe fields and magnetic interference cause difficulties in beam matching. We have performed 3D simulations of the magnets, computed their optical properties, and compared their performance with what predicted by simple hard edge models. This paper reports our findings and a general solution to the problem.
Beta scaling of transport in microturbulence simulations
Candy, J.
2005-07-15
A systematic study of the beta ({beta}) scaling and spatial structure of thermal and particle transport in gyrokinetic turbulence simulations is presented. Here, {beta} is the ratio of the plasma kinetic pressure to the magnetic pressure. Results show that the nonlinear self-consistent temperature profiles exhibit a (statistically) time-stationary flattening in the vicinity of rational surfaces with a concomitant drop in the electrostatic components of the thermal diffusivity. Simultaneously, the increased magnetic fluctuation amplitude at these surfaces enhances the steady-state electromagnetic (flutter) component of the electron thermal diffusivity. The electromagnetic components of the ion transport coefficients remain close to zero, as expected on theoretical grounds. Only a weak dependence of ion energy transport on {beta} is observed, consistent with recent tokamak experiments [C. C. Petty et al., Phys. Plasmas 11, 2514 (2004)].
Nonlinear hybrid simulation of internal kink with beam ion effects in DIII-D
Shen, Wei; Sheng, Zheng-Mao; Fu, G. Y.; Tobias, Benjamin; Zeeland, Michael Van; Wang, Feng
2015-04-15
In DIII-D sawteething plasmas, long-lived (1,1) kink modes are often observed between sawtooth crashes. The saturated kink modes have two distinct frequencies. The mode with higher frequency transits to a fishbone-like mode with sufficient on-axis neutral beam power. In this work, hybrid simulations with the global kinetic-magnetohydrodynamic (MHD) hybrid code M3D-K have been carried out to investigate the linear stability and nonlinear dynamics of the n = 1 mode with effects of energetic beam ions for a typical DIII-D discharge where both saturated kink mode and fishbone were observed. Linear simulation results show that the n = 1 internal kink mode is unstable in MHD limit. However, with kinetic effects of beam ions, a fishbone-like mode is excited with mode frequency about a few kHz depending on beam pressure profile. The mode frequency is higher at higher beam power and/or narrower radial profile consistent with the experimental observation. Nonlinear simulations have been performed to investigate mode saturation as well as energetic particle transport. The nonlinear MHD simulations show that the unstable kink mode becomes a saturated kink mode after a sawtooth crash. With beam ion effects, the fishbone-like mode can also transit to a saturated kink mode with a small but finite mode frequency. These results are consistent with the experimental observation of saturated kink mode between sawtooth crashes.
Modern Foundations of Light Transport Simulation
NASA Astrophysics Data System (ADS)
Lessig, Christian
Light transport simulation aims at the numerical computation of the propagation of visible electromagnetic energy in macroscopic environments. In this thesis, we develop the foundations for a modern theory of light transport simulation, unveiling the geometric structure of the continuous theory and providing a formulation of computational techniques that furnishes remarkably efficacy with only local information. Utilizing recent results from various communities, we develop the physical and mathematical structure of light transport from Maxwell's equations by studying a lifted representation of electromagnetic theory on the cotangent bundle. At the short wavelength limit, this yields a Hamiltonian description on six-dimensional phase space, with the classical formulation over the space of "positions and directions" resulting from a reduction to the five-dimensional cosphere bundle. We establish the connection between light transport and geometrical optics by a non-canonical Legendre transform, and we derive classical concepts from radiometry, such as radiance and irradiance, by considering measurements of the light energy density. We also show that in idealized environments light transport is a Lie-Poisson system for the group of symplectic diffeomorphisms, unveiling a tantalizing similarity between light transport and fluid dynamics. Using Stone's theorem, we also derive a functional analytic description of light transport. This bridges the gap to existing formulations in the literature and naturally leads to computational questions. We then address one of the central challenges for light transport simulation in everyday environments with scattering surfaces: how are efficient computations possible when the light energy density can only be evaluated pointwise? Using biorthogonal and possibly overcomplete bases formed by reproducing kernel functions, we develop a comprehensive theory for computational techniques that are restricted to pointwise information
Simulation of ion beam scattering in a gas stripper
NASA Astrophysics Data System (ADS)
Maxeiner, Sascha; Suter, Martin; Christl, Marcus; Synal, Hans-Arno
2015-10-01
Ion beam scattering in the gas stripper of an accelerator mass spectrometer (AMS) enlarges the beam phase space and broadens its energy distribution. As the size of the injected beam depends on the acceleration voltage through phase space compression, the stripper becomes a limiting factor of the overall system transmission especially for low energy AMS system in the sub MV region. The spatial beam broadening and collisions with the accelerator tube walls are a possible source for machine background and energy loss fluctuations influence the mass resolution and thus isotope separation. To investigate the physical processes responsible for these effects, a computer simulation approach was chosen. Monte Carlo simulation methods are applied to simulate elastic two body scattering processes in screened Coulomb potentials in a (gas) stripper and formulas are derived to correctly determine random collision parameters and free path lengths for arbitrary (and non-homogeneous) gas densities. A simple parametric form for the underlying scattering cross sections is discussed which features important scaling behaviors. An implementation of the simulation was able to correctly model the data gained with the TANDY AMS system at ETH Zurich. The experiment covered transmission measurements of uranium ions in helium and beam profile measurements after the ion beam passed through the He-stripper. Beam profiles measured up to very high stripper densities could be understood in full system simulations including the relevant ion optics. The presented model therefore simulates the fundamental physics of the interaction between an ion beam and a gas stripper reliably. It provides a powerful and flexible tool for optimizing existing AMS stripper geometries and for designing new, state of the art low energy AMS systems.
Gyrokinetic simulations of ion and impurity transport
Estrada-Mila, C.; Candy, J.; Waltz, R.E.
2005-02-01
A systematic study of turbulent particle and energy transport in both pure and multicomponent plasmas is presented. In this study, gyrokinetic results from the GYRO code [J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] are supplemented with those from the GLF23 [R. E. Waltz, G. M. Staebler, W. Dorland et al., Phys. Plasmas 4, 2482 (1997)] transport model, as well as from quasilinear theory. Various results are obtained. The production of a particle pinch driven by temperature gradients (a thermal pinch) is demonstrated, and further shown to be weakened by finite electron collisionality. Helium transport and the effects of helium density gradient and concentration in a deuterium plasma are examined. Interestingly, it is found that the simple D-v (diffusion versus convective velocity) model of impurity flow is consistent with results obtained from nonlinear gyrokinetic simulations. Also studied is the transport in a 50-50 deuterium-tritium plasma, where a symmetry breaking is observed indicating the potential for fuel separation in a burning plasma. Quasilinear theory together with linear simulations shows that the symmetry breaking which enhances the tritium confinement arises largely from finite-Larmor-radius effects. To justify the numerical methods used in the paper, a variety of linear benchmarks and nonlinear grid refinement studies are detailed.
SciDAC Advances in Beam Dynamics Simulation: From Light Sources to Colliders
Qiang, J.; Borland, M.; Kabel, A.; Li, R.; Ryne, R.; Stern, E.; Wang, Y.; Wasserman, H.; Zhang, Y.; /SLAC
2011-11-14
In this paper, we report on progress that has been made in beam dynamics simulation, from light sources to colliders, during the first year of the SciDAC-2 accelerator project 'Community Petascale Project for Accelerator Science and Simulation (ComPASS).' Several parallel computational tools for beam dynamics simulation are described. Also presented are number of applications in current and future accelerator facilities (e.g., LCLS, RHIC, Tevatron, LHC, and ELIC). Particle accelerators are some of most important tools of scientific discovery. They are widely used in high-energy physics, nuclear physics, and other basic and applied sciences to study the interaction of elementary particles, to probe the internal structure of matter, and to generate high-brightness radiation for research in materials science, chemistry, biology, and other fields. Modern accelerators are complex and expensive devices that may be several kilometers long and may consist of thousands of beamline elements. An accelerator may transport trillions of charged particles that interact electromagnetically among themselves, that interact with fields produced by the accelerator components, and that interact with beam-induced fields. Large-scale beam dynamics simulations on massively parallel computers can help provide understanding of these complex physical phenomena, help minimize design cost, and help optimize machine operation. In this paper, we report on beam dynamics simulations in a variety of accelerators ranging from next generation light sources to high-energy ring colliders that have been studied during the first year of the SciDAC-2 accelerator project.
Transport delays associated with NASA Langley Flight Simulation Facility
NASA Technical Reports Server (NTRS)
Smith, R. Marshall; Chung, Victoria I.; Martinez, Debbie
1995-01-01
This paper describes the transport delays associated with flight simulation programs currently operating at the NASA Langley Research Center (LaRC). Formulas are presented for calculating a rough estimate of the transport delay for a particular simulation. Various simulation programs that used the Flight Simulation Facility at LaRC, during the period of October 1993 to March 1994, were tested to determine the transport delays associated with the simulation program and any associated hardware. Several simulators were tested, including the Differential Maneuvering Simulator (DMS), the Visual Motion Simulator (VMS), and the Transport System Research Vehicle (TSRV).
NASA Astrophysics Data System (ADS)
Kim, J.; McGuffey, C.; Qiao, B.; Beg, F. N.; Wei, M. S.; Grabowski, P. E.
2015-11-01
With intense proton beams accelerated by high power short pulse lasers, solid targets are isochorically heated to become partially-ionized warm or hot dense matter. In this regime, the thermodynamic state of the matter significantly changes, varying the proton stopping power where both bound and free electrons contribute. Additionally, collective beam-matter interaction becomes important to the beam transport. We present self-consistent hybrid particle-in-cell (PIC) simulation results of proton beam transport and energy deposition in solid-density matter, where the individual proton stopping and the collective effects are taken into account simultaneously with updates of stopping power in the varying target conditions and kinetic motions of the beam in the driven fields. Broadening of propagation range and self-focusing of the beam led to unexpected target heating by the intense proton beams, with dependence on the beam profiles and target conditions. The behavior is specifically studied for the case of an experimentally measured proton beam from the 1.25 kJ, 10 ps OMEGA EP laser transporting through metal foils. This work was supported by the U.S. DOE under Contracts No. DE-NA0002034 and No. DE-AC52-07NA27344 and by the U.S. AFOSR under Contract FA9550-14-1-0346.
Maidana, C. O.; Hunt, A. W.; Beller, D.; Folkman, K.
2007-02-12
As part of the Reactor Accelerator Coupling Experiment (RACE) a set of preliminary studies were conducted to design a transport beam line that could bring a 25 MeV electron beam from a Linear Accelerator to a neutron-producing target inside a subcritical system. Because of the relatively low energy beam, the beam size and a relatively long beam line (implicating a possible divergence problem) different parameters and models were studied before a final design could be submitted for assembly. This report shows the first results obtained from different simulations of the transport line optics and dynamics.
NASA Astrophysics Data System (ADS)
Maidana, Carlos O.; Hunt, Alan W.; Beller, Denis; Folkman, Kevin
2006-06-01
As part of the Reactor Accelerator Coupling Experiment (RACE) a set of preliminary studies were conducted to design a transport beam line that could bring a 25 MeV electron beam from a linear accelerator to a neutron-producing target inside a subcritical system. Because of the relatively low energy beam, the beam size and a relatively long beam line (implicating a possible divergence problem) different parameters and models were studied before a final design could be submitted for assembly. This report shows the results obtained from different simulations for different lattices of the transport line optics and dynamics.
NASA Astrophysics Data System (ADS)
Maidana, C. O.; Hunt, A. W.; Beller, D.; Folkman, K.
2007-02-01
As part of the Reactor Accelerator Coupling Experiment (RACE) a set of preliminary studies were conducted to design a transport beam line that could bring a 25 MeV electron beam from a Linear Accelerator to a neutron-producing target inside a subcritical system. Because of the relatively low energy beam, the beam size and a relatively long beam line (implicating a possible divergence problem) different parameters and models were studied before a final design could be submitted for assembly. This report shows the first results obtained from different simulations of the transport line optics and dynamics.
Measurement of power density distribution and beam waist simulation for electron beam
NASA Astrophysics Data System (ADS)
Shen, Chunlong; Peng, Yong; Wang, Kehong; Zhou, Qi
2013-02-01
The study aims to measure the power density distribution of the electron beam (EB) for further estimating its characteristics. A compact device combining deflection signal controller and current signal acquisition circuit of the EB was built. A software modelling framework was developed to investigate structural parameters of the electron beam. With an iterative algorithm, the functional relationship between the electron beam power and its power density was solved and the corresponding contour map of power density distribution was plotted through isoline tracking approach. The power density distribution of various layers of cross-section beam was reconstructed for beam volume by direct volume rendering technique. The further simulation of beam waist with all-known marching cubes algorithm reveals the evolution of spatial appearance and geometry measurement principle was explained in detail. The study provides an evaluation of promising to replace the traditional idea of EB spatial characteristics.
Simulation framework for intelligent transportation systems
Ewing, T.; Doss, E.; Hanebutte, U.; Tentner, A.
1996-10-01
A simulation framework has been developed for a large-scale, comprehensive, scaleable simulation of an Intelligent Transportation System (ITS). The simulator is designed for running on parallel computers and distributed (networked) computer systems, but can run on standalone workstations for smaller simulations. The simulator currently models instrumented smart vehicles with in-vehicle navigation units capable of optimal route planning and Traffic Management Centers (TMC). The TMC has probe vehicle tracking capabilities (display position and attributes of instrumented vehicles), and can provide two-way interaction with traffic to provide advisories and link times. Both the in-vehicle navigation module and the TMC feature detailed graphical user interfaces to support human-factors studies. Realistic modeling of variations of the posted driving speed are based on human factors studies that take into consideration weather, road conditions, driver personality and behavior, and vehicle type. The prototype has been developed on a distributed system of networked UNIX computers but is designed to run on parallel computers, such as ANL`s IBM SP-2, for large-scale problems. A novel feature of the approach is that vehicles are represented by autonomous computer processes which exchange messages with other processes. The vehicles have a behavior model which governs route selection and driving behavior, and can react to external traffic events much like real vehicles. With this approach, the simulation is scaleable to take advantage of emerging massively parallel processor (MPP) systems.
NASA Astrophysics Data System (ADS)
Read, Martin; Kingham, Robert; Bissell, John
2016-05-01
The propagation of a nanosecond IR laser pulse through an under-dense (0.01 — 0.1ncr) magnetised laser-plasma is considered. The interplay between magnetised transport, B-field evolution and plasma hydrodynamics in the presence of a dynamically evolving beam are investigated by means of a paraxial wave solving module coupled to CTC, a 2D MHD code including Braginskii electron transport and IMPACT, a 2D implicit Vlasov-Fokker-Planck (VFP) code with magnetic fields. Magnetic fields have previously been shown to improve density channel formation for plasma waveguides however fluid simulations presented here indicate that Nernst advection can result in the rapid cavitation of magnetic field in the laser-heated region resulting in beam defocusing. Kinetic simulations indicate that strong non-local transport is present leading to the fluid code overestimating heat-flow and magnetic field advection and resulting in the recovery of beam channelling for the conditions considered.
Nonlinear delta(f) Simulations of Collective Effects in Intense Charged Particle Beams
Hong Qin
2003-01-21
A nonlinear delta(f) particle simulation method based on the Vlasov-Maxwell equations has been recently developed to study collective processes in high-intensity beams, where space-charge and magnetic self-field effects play a critical role in determining the nonlinear beam dynamics. Implemented in the Beam Equilibrium, Stability and Transport (BEST) code [H. Qin, R.C. Davidson, and W.W. Lee, Physical Review -- Special Topics on Accelerator and Beams 3 (2000) 084401; 3 (2000) 109901.], the nonlinear delta(f) method provides a low-noise and self-consistent tool for simulating collective interactions and nonlinear dynamics of high-intensity beams in modern and next-generation accelerators and storage rings, such as the Spallation Neutron Source and heavy ion fusion drivers. A wide range of linear eigenmodes of high-intensity charged-particle beams can be systematically studied using the BEST code. Simulation results for the electron-proton two-stream instability in the Proton Storage Ring experiment [R. Macek, et al., in Proc. of the Particle Accelerator Conference, Chicago, 2001 (IEEE, Piscataway, NJ, 2001), Vol. 1, p. 688.] at the Los Alamos National Laboratory agree well with experimental observations. Large-scale parallel simulations have also been carried out for the ion-electron two-stream instability in the very-high-intensity heavy ion beams envisioned for heavy ion fusion applications. In both cases, the simulation results indicate that the dominant two-stream instability has a dipole-mode (hose-like) structure and can be stabilized by a modest axial momentum spread of the beam particles.
Status of the PXIE Low Energy Beam Transport Line
Prost, Lionel; Andrews, Richard; Chen, Alex; Hanna, Bruce; Scarpine, Victor; Shemyakin, Alexander; Steimel, Jim; D'Arcy, Richard
2014-07-01
A CW-compatible, pulsed H^{-} superconducting RF linac (a.k.a. PIP-II) is envisaged as a possible path for upgrading Fermilab’s injection complex [1]. To validate the concept of the front-end of such machine, a test accelerator (a.k.a. PXIE) [2] is under construction. The warm part of this accelerator comprises a 10 mA DC, 30 keV H^{-} ion source, a 2m-long LEBT, a 2.1 MeV CW RFQ, and a MEBT that feeds the first cryomodule. In addition to operating in the nominal CW mode, the LEBT should be able to produce a pulsed beam for both PXIE commissioning and modelling of the front-end nominal operation in the pulsed mode. Concurrently, it needs to provide effective means of inhibiting beam as part of the overall machine protection system. A peculiar feature of the present LEBT design is the capability of using the ~1m-long section immediately preceding the RFQ in two regimes of beam transport dynamics: neutralized and space charge dominated. This paper introduces the PXIE LEBT, reports on the status of the ion source and LEBT installation, and presents the first beam measurements.
Measurements and simulations of focused beam for orthovoltage therapy
Abbas, Hassan; Mahato, Dip N.; Satti, Jahangir; MacDonald, C. A.
2014-01-01
Purpose: Megavoltage photon beams are typically used for therapy because of their skin-sparing effect. However, a focused low-energy x-ray beam would also be skin sparing, and would have a higher dose concentration at the focal spot. Such a beam can be produced with polycapillary optics. MCNP5 was used to model dose profiles for a scanned focused beam, using measured beam parameters. The potential of low energy focused x-ray beams for radiation therapy was assessed. Methods: A polycapillary optic was used to focus the x-ray beam from a tungsten source. The optic was characterized and measurements were performed at 50 kV. PMMA blocks of varying thicknesses were placed between optic and the focal spot to observe any variation in the focusing of the beam after passing through the tissue-equivalent material. The measured energy spectrum was used to model the focused beam in MCNP5. A source card (SDEF) in MCNP5 was used to simulate the converging x-ray beam. Dose calculations were performed inside a breast tissue phantom. Results: The measured focal spot size for the polycapillary optic was 0.2 mm with a depth of field of 5 mm. The measured focal spot remained unchanged through 40 mm of phantom thickness. The calculated depth dose curve inside the breast tissue showed a dose peak several centimeters below the skin with a sharp dose fall off around the focus. The percent dose falls below 10% within 5 mm of the focus. It was shown that rotating the optic during scanning would preserve the skin-sparing effect of the focused beam. Conclusions: Low energy focused x-ray beams could be used to irradiate tumors inside soft tissue within 5 cm of the surface. PMID:24694122
Measurements and simulations of focused beam for orthovoltage therapy
Abbas, Hassan; Mahato, Dip N.; Satti, Jahangir; MacDonald, C. A.
2014-04-15
Purpose: Megavoltage photon beams are typically used for therapy because of their skin-sparing effect. However, a focused low-energy x-ray beam would also be skin sparing, and would have a higher dose concentration at the focal spot. Such a beam can be produced with polycapillary optics. MCNP5 was used to model dose profiles for a scanned focused beam, using measured beam parameters. The potential of low energy focused x-ray beams for radiation therapy was assessed. Methods: A polycapillary optic was used to focus the x-ray beam from a tungsten source. The optic was characterized and measurements were performed at 50 kV. PMMA blocks of varying thicknesses were placed between optic and the focal spot to observe any variation in the focusing of the beam after passing through the tissue-equivalent material. The measured energy spectrum was used to model the focused beam in MCNP5. A source card (SDEF) in MCNP5 was used to simulate the converging x-ray beam. Dose calculations were performed inside a breast tissue phantom. Results: The measured focal spot size for the polycapillary optic was 0.2 mm with a depth of field of 5 mm. The measured focal spot remained unchanged through 40 mm of phantom thickness. The calculated depth dose curve inside the breast tissue showed a dose peak several centimeters below the skin with a sharp dose fall off around the focus. The percent dose falls below 10% within 5 mm of the focus. It was shown that rotating the optic during scanning would preserve the skin-sparing effect of the focused beam. Conclusions: Low energy focused x-ray beams could be used to irradiate tumors inside soft tissue within 5 cm of the surface.
Beam-transport optimization for cold-neutron spectrometer
NASA Astrophysics Data System (ADS)
Nakajima, Kenji; Ohira-Kawamura, Seiko; Kikuchi, Tatsuya; Kajimoto, Ryoichi; Takahashi, Nobuaki; Nakamura, Mitsutaka; Soyama, Kazuhiko; Osakabe, Toyotaka
2015-01-01
We report the design of the beam-transport system (especially the vertical geometry) for a cold-neutron disk-chopper spectrometer AMATERAS at J-PARC. Based on the elliptical shape, which is one of the most effective geometries for a ballistic mirror, the design was optimized to obtain, at the sample position, a neutron beam with high flux without serious degrading in divergence and spacial homogeneity within the boundary conditions required from actual spectrometer construction. The optimum focal point was examined. An ideal elliptical shape was modified to reduce its height without serious loss of transmission. The final result was adapted to the construction requirements of AMATERAS. Although the ideas studied in this paper are considered for the AMATERAS case, they can be useful also to other spectrometers in similar situations.
Ion transport studies on the PLT tokamak during neutral beam injection
Suckewer, S.; Cavallo, A.; Cohen, S.; Daughney, C.; Denne, B.; Hinnov, E.; Hosea, J.; Hulse, R.; Hwang, D.; Schilling, G.
1983-12-01
Radial transport of ions during co- and counter-neutral beam heating in the PLT tokamak has been studied, using molybdenum and scandium ions as tracer elements. The time evolution of the radial profiles of several ionization stages of both elements, injected by laser blowoff during the neutral beam heating, were measured under three significantly different beam-plasma combinations. No noticeable differences in the radial profiles attributable to the beam direction were observed. However, a given injected amount resulted in considerably larger interior concentrations of the tracer element in the counter-beam heating cases, suggesting larger penetration of the plasma periphery. Computer simulation with the MIST code suggests a net inward drift of the order 10/sup 3/ cm/sec superposed to a diffusion coefficient of the order 10/sup 4/ cm/sup 2//sec for both scandium and molybdenum ions. Injection of larger amounts of the tracer element, sufficient to cause measurable central electron temperature changes, resulted in dramatic changes in ion-state distributions, making some appear peaked in the center while others disappeared. This effect could be produced with both co- and counter-beam heating, but with lesser amounts in the latter case. It is interpreted as rearrangement of the ionization balance, rather than any preferential accumulation of the injected element.
Studies on low energy beam transport for high intensity high charged ions at IMP
Yang, Y. Lu, W.; Fang, X.; University of Chinese Academy of Sciences, Beijing 100039 ; Sun, L. T.; Hu, Q.; Cao, Y.; Feng, Y. C.; Zhang, X. Z.; Zhao, H. W.; Xie, D. Z.
2014-02-15
Superconducting Electron Cyclotron Resonance ion source with Advanced design in Lanzhou (SECRAL) is an advanced fully superconducting ECR ion source at IMP designed to be operational at the microwave frequency of 18–24 GHz. The existing SECRAL beam transmission line is composed of a solenoid lens and a 110° analyzing magnet. Simulations of particle tracking with 3D space charge effect and realistic 3D magnetic fields through the line were performed using particle-in-cell code. The results of the beam dynamics show that such a low energy beam is very sensitive to the space charge effect and significantly suffers from the second-order aberration of the analyzing magnet resulting in large emittance. However, the second-order aberration could be reduced by adding compensating sextupole components in the beam line. On this basis, a new 110° analyzing magnet with relatively larger acceptance and smaller aberration is designed and will be used in the design of low energy beam transport line for a new superconducting ECR ion source SECRAL-II. The features of the analyzer and the corresponding beam trajectory calculation will be detailed and discussed in this paper.
Studies on low energy beam transport for high intensity high charged ions at IMP.
Yang, Y; Sun, L T; Hu, Q; Cao, Y; Lu, W; Feng, Y C; Fang, X; Zhang, X Z; Zhao, H W; Xie, D Z
2014-02-01
Superconducting Electron Cyclotron Resonance ion source with Advanced design in Lanzhou (SECRAL) is an advanced fully superconducting ECR ion source at IMP designed to be operational at the microwave frequency of 18-24 GHz. The existing SECRAL beam transmission line is composed of a solenoid lens and a 110° analyzing magnet. Simulations of particle tracking with 3D space charge effect and realistic 3D magnetic fields through the line were performed using particle-in-cell code. The results of the beam dynamics show that such a low energy beam is very sensitive to the space charge effect and significantly suffers from the second-order aberration of the analyzing magnet resulting in large emittance. However, the second-order aberration could be reduced by adding compensating sextupole components in the beam line. On this basis, a new 110° analyzing magnet with relatively larger acceptance and smaller aberration is designed and will be used in the design of low energy beam transport line for a new superconducting ECR ion source SECRAL-II. The features of the analyzer and the corresponding beam trajectory calculation will be detailed and discussed in this paper. PMID:24593453
Theory and simulation of the beam cyclotron instability.
NASA Technical Reports Server (NTRS)
Lampe, M.; Manheimer, W. M.; Mcbride, J. B.; Orens, J. H.; Papadopoulos, K.; Shanny, R.; Sudan, R. N.
1972-01-01
A theory of plasma beam cyclotron instability is developed on the basis of computer simulation experiments. The theory holds that at certain turbulence levels, electron cross-field diffusion which supresses the electron gyroresonances is created by turbulent wave-particle interactions in a plasma beam after a period of quasi-linear exponential development of turbulence. The stabilizing effect of Landau ion damping is noted. The behavior of cold and hot ions is discussed.
Simulations of longitudinal beam dynamics of space-charge dominated beams for heavy ion fusion
Miller, D.A.C.
1994-12-01
The longitudinal instability has potentially disastrous effects on the ion beams used for heavy ion driven inertial confinement fusion. This instability is a {open_quotes}resistive wall{close_quotes} instability with the impedance coining from the induction modules in the accelerator used as a driver. This instability can greatly amplify perturbations launched from the beam head and can prevent focusing of the beam onto the small spot necessary for fusion. This instability has been studied using the WARPrz particle-in-cell code. WARPrz is a 2 1/2 dimensional electrostatic axisymmetric code. This code includes a model for the impedance of the induction modules. Simulations with resistances similar to that expected in a driver show moderate amounts of growth from the instability as a perturbation travels from beam head to tail as predicted by cold beam fluid theory. The perturbation reflects off the beam tail and decays as it travels toward the beam head. Nonlinear effects cause the perturbation to steepen during reflection. Including the capacitive component of the, module impedance. has a partially stabilizing effect on the longitudinal instability. This reduction in the growth rate is seen in both cold beam fluid theory and in simulations with WARPrz. Instability growth rates for warm beams measured from WARPrz are lower than cold beam fluid theory predicts. Longitudinal thermal spread cannot account for this decrease in the growth rate. A mechanism for coupling the transverse thermal spread to decay of the longitudinal waves is presented. The longitudinal instability is no longer a threat to the heavy ion fusion program. The simulations in this thesis have shown that the growth rate for this instability will not be as large as earlier calculations predicted.
Advanced Civil Transport Simulator Cockpit View
NASA Technical Reports Server (NTRS)
1992-01-01
The Advanced Civil Transport Simulator (ACTS) is a futuristic aircraft cockpit simulator designed to provide full-mission capabilities for researching issues that will affect future transport aircraft flight stations and crews. The objective is to heighten the pilots situation awareness through improved information availability and ease of interpretation in order to reduce the possibility of misinterpreted data. The simulators five 13-inch Cathode Ray Tubes are designed to display flight information in a logical easy-to-see format. Two color flat panel Control Display Units with touch sensitive screens provide monitoring and modification of aircraft parameters, flight plans, flight computers, and aircraft position. Three collimated visual display units have been installed to provide out-the-window scenes via the Computer Generated Image system. The major research objectives are to examine needs for transfer of information to and from the flight crew; study the use of advanced controls and displays for all-weather flying; explore ideas for using computers to help the crew in decision making; study visual scanning and reach behavior under different conditions with various levels of automation and flight deck-arrangements.
Iterated transportation simulations for Dallas and Portland
Nagel, K.; Simon, P.; Rickert, M.; Esser, J.
1998-09-02
The goal of the TRansportation ANalysis and SIMulation System (TRANSIMS) is to combine the most important aspects of human decision-making related to transportation, from activities planning (sleep, work, eat, shop,...) via modal and route planning to driving, into a single, consistent methodological and software framework. This is meant to combine the functionalities of activities-based travel demand generation, modal choice and route assignment, and micro-simulation. TRANSIMS attempts to employ advanced methodologies in all these modules. Yet, it is probably the overall framework that is the most important part of this attempt. It is, for example, possible to replace the TRANSIMS microsimulation by another micro-simulation that uses the same input and generates the same output. TRANSIMS uses specific regions as examples in order to ensure that the technology is rooted in the real world. Until about the middle of 1997, an approximately five miles by five miles area in Dallas/Texas was used. Since then, TRANSIMS has moved to using data from Portland/Oregon; a case study for this region is planned to be completed by the end of the year 2000. In this paper the authors give short descriptions of these projects and give references to related publications.
Exposure simulation of electron beam microcolumn lithography
NASA Astrophysics Data System (ADS)
Kim, Sang-Kon; Oh, Hye-Keun
2004-05-01
We propose an improved method to describe the electron-resist interaction based on Dill"s model for exposure simulation. For this purpose, Monte Carlo simulation was performed to obtain the energy intensity distribution in the chemically amplified resist. Tabulated Mott data for elastic scattering, Moller and Vriens cross sections for inelastic scattering, and Modified Bethe equation plus discrete energy loss for energy loss are used for the calculation of the energy intensity distribution. Through the electron-resist interaction, the energy intensity distribution changes resist components into the exposure production such as the photoacid concentration or the photoacid generator inside resists with various pattern shapes by using the modified Dill"s model. Our simulation profiles show a good agreement with experimental profiles.
NASA Astrophysics Data System (ADS)
Qin, Hong; Davidson, Ronald C.; Startsev, Edward A.
2004-11-01
A wide range of collective effects in high intensity charged particle beams have been numerically studied using the nonlinear delta-f particle simulation method implemented in the Beam Equilibrium Stability and Transport (BEST) code. For the electron-ion two-stream instability in high intensity accelerators and storage rings, the secondary electron yield effects are self-consistently studied by coupling the secondary electron yield library CMEE with the instability simulations. Progress has also been made in applying the delta-f particle simulation method to bunched beams, and a three-dimensional equilibrium solver has been implemented. With the help of recently developed parallel diagnostic techniques, we are able to characterize the chaotic particle dynamics under the influences of collective instabilities as well as three-dimensional equilibrium fields. To further extend the application areas of the delta-f particle simulation method, 2D domain decomposition is being developed using the Message Passing Interface, and three-dimensional equilibria with anisotropic temperature in the transverse and longitudinal directions are being investigated. References: [1] R. C. Davidson and H. Qin, An Introduction to the Physics of Intense Charged Particle Beams in High Energy Accelerators, World Scientific (2001). [2] H. Qin, Physics of Plasmas 10, 2078 (2003). [3] H. Qin, E. A. Startsev, and R. C. Davidson, Physical Review Special Topics on Accelerators and Beams 6, 014401 (2003).
MSTS - Multiphase Subsurface Transport Simulator theory manual
White, M.D.; Nichols, W.E.
1993-05-01
The US Department of Energy, through the Yucca Mountain Site Characterization Project Office, has designated the Yucca Mountain site in Nevada for detailed study as the candidate US geologic repository for spent nuclear fuel and high-level radioactive waste. Site characterization will determine the suitability of the Yucca Mountain site for the potential waste repository. If the site is determined suitable, subsequent studies and characterization will be conducted to obtain authorization from the Nuclear Regulatory Commission to construct the potential waste repository. A principal component of the characterization and licensing processes involves numerically predicting the thermal and hydrologic response of the subsurface environment of the Yucca Mountain site to the potential repository over a 10,000-year period. The thermal and hydrologic response of the subsurface environment to the repository is anticipated to include complex processes of countercurrent vapor and liquid migration, multiple-phase heat transfer, multiple-phase transport, and geochemical reactions. Numerical simulators based on mathematical descriptions of these subsurface phenomena are required to make numerical predictions of the thermal and hydrologic response of the Yucca Mountain subsurface environment The engineering simulator called the Multiphase Subsurface Transport Simulator (MSTS) was developed at the request of the Yucca Mountain Site Characterization Project Office to produce numerical predictions of subsurface flow and transport phenomena at the potential Yucca Mountain site. This document delineates the design architecture and describes the specific computational algorithms that compose MSTS. Details for using MSTS and sample problems are given in the {open_quotes}User`s Guide and Reference{close_quotes} companion document.
Lateral spin transport in paraxial beams of light.
Neugebauer, Martin; Grosche, Simon; Rothau, Sergej; Leuchs, Gerd; Banzer, Peter
2016-08-01
We investigate the lateral transport of (longitudinal) spin angular momentum in a special polarization tailored light beam composed of a superposition of a y-polarized zero-order and an x-polarized first-order Hermite-Gaussian mode. This phenomenon is linked to the relative Gouy phase shift between the individual modes upon propagation, but can also be interpreted as a geometric phase effect. Experimentally, we demonstrate the implementation of such a mode and measure the spin density upon propagation. PMID:27472603
Electron Beam Transport in Advanced Plasma Wave Accelerators
Williams, Ronald L
2013-01-31
The primary goal of this grant was to develop a diagnostic for relativistic plasma wave accelerators based on injecting a low energy electron beam (5-50keV) perpendicular to the plasma wave and observing the distortion of the electron beam's cross section due to the plasma wave's electrostatic fields. The amount of distortion would be proportional to the plasma wave amplitude, and is the basis for the diagnostic. The beat-wave scheme for producing plasma waves, using two CO2 laser beam, was modeled using a leap-frog integration scheme to solve the equations of motion. Single electron trajectories and corresponding phase space diagrams were generated in order to study and understand the details of the interaction dynamics. The electron beam was simulated by combining thousands of single electrons, whose initial positions and momenta were selected by random number generators. The model was extended by including the interactions of the electrons with the CO2 laser fields of the beat wave, superimposed with the plasma wave fields. The results of the model were used to guide the design and construction of a small laboratory experiment that may be used to test the diagnostic idea.
Simple Beam-Optic Simulations and Proposed Mechanical Mitigation for the Triplet Oscillation Problem
Thieberger,P.; Montag, C.; Snydstrup, L.; Trbojevic, D.; Tuozzolo, J.
2008-05-01
The purpose of these simulations is to gain a better understanding of the relative contributions to the beam perturbation from the main horizontal oscillation modes (yawing and rolling) of Q1, Q2, and Q3. For this purpose, a simple beam transport program was implemented with an EXCEL spreadsheet to calculate the horizontal beam envelop through the Q1, Q2, Q3 triplet up to the IP, with the possibility of specifying horizontal displacements of the singlets. For now, the weak focusing properties of D0 and DX have been ignored, but could easily be included in the future if necessary. In a first simulation, quadrupole strengths have been adopted that correspond to {beta}* = 2m at the IP. The parameters used listed in Table 1 were obtained from references [1] and [2].
Numerical Simulation of Beam-Beam Effects in the Proposed Electron-Ion Colider at Jefferson Lab
Balsa Terzic, Yuhong Zhang
2010-05-01
One key limiting factor to a collider luminosity is beam-beam interactions which usually can cause serious emittance growth of colliding beams and fast reduction of luminosity. Such nonlinear collective beam effect can be a very serious design challenge when the machine parameters are pushed into a new regime. In this paper, we present simulation studies of the beam-beam effect for a medium energy ring-ring electron-ion collider based on CEBAF.
Evaluation of the BEAM--BEAM effect in PEP using Myer's simulation program
Hutton, A.
1982-09-01
The program BEAM BEAM written by Steve Myers for the LEP machine at CERN has given encouraging results in the simulation of the beam-beam effect in electron-positron storage rings. It therefore seemed worthwhile to apply the program to PEP with two main intentions. Firstly, to confirm the validity of the program by comparison with experimental data from previous PEP runs and secondly, to search for an improvement in the operating conditions of PEP. Clearly a successful prediction would also enhance the credibility of the program. The program itself has been extensively described in the literature and will not be repeated here, except for some comments of direct relevance to the present simulation. 14 refs., 15 figs., 4 tabs.
DART: a simulation code for charged particle beams
White, R.C.; Barr, W.L.; Moir, R.W.
1988-05-16
This paper presents a recently modified verion of the 2-D DART code designed to simulate the behavior of a beam of charged particles whose paths are affected by electric and magnetic fields. This code was originally used to design laboratory-scale and full-scale beam direct converters. Since then, its utility has been expanded to allow more general applications. The simulation technique includes space charge, secondary electron effects, and neutral gas ionization. Calculations of electrode placement and energy conversion efficiency are described. Basic operation procedures are given including sample input files and output. 7 refs., 18 figs.
Rare event simulation in radiation transport
Kollman, C.
1993-10-01
This dissertation studies methods for estimating extremely small probabilities by Monte Carlo simulation. Problems in radiation transport typically involve estimating very rare events or the expected value of a random variable which is with overwhelming probability equal to zero. These problems often have high dimensional state spaces and irregular geometries so that analytic solutions are not possible. Monte Carlo simulation must be used to estimate the radiation dosage being transported to a particular location. If the area is well shielded the probability of any one particular particle getting through is very small. Because of the large number of particles involved, even a tiny fraction penetrating the shield may represent an unacceptable level of radiation. It therefore becomes critical to be able to accurately estimate this extremely small probability. Importance sampling is a well known technique for improving the efficiency of rare event calculations. Here, a new set of probabilities is used in the simulation runs. The results are multiple by the likelihood ratio between the true and simulated probabilities so as to keep the estimator unbiased. The variance of the resulting estimator is very sensitive to which new set of transition probabilities are chosen. It is shown that a zero variance estimator does exist, but that its computation requires exact knowledge of the solution. A simple random walk with an associated killing model for the scatter of neutrons is introduced. Large deviation results for optimal importance sampling in random walks are extended to the case where killing is present. An adaptive ``learning`` algorithm for implementing importance sampling is given for more general Markov chain models of neutron scatter. For finite state spaces this algorithm is shown to give with probability one, a sequence of estimates converging exponentially fast to the true solution.
Simulation of chamber transport for heavy-ion fusion
Sharp, W.M.; Callahan, D.A.; Tabak, M.A.; Yu, S.S.; Peterson, P.F.; Rose, D.V.; Welch, D.R.; Davidson, R.C.; Kaganovich, I.D.; Startsev, E.; Olson, C.L.
2002-10-04
Beams for heavy-ion fusion (HIF) are expected to require substantial neutralization in a target chamber. Present targets call for higher beam currents and smaller focal spots than most earlier designs, leading to high space-charge fields. Collisional stripping by the background gas expected in the chamber further increases the beam charge. Simulations with no electron sources other than beam stripping and background-gas ionization show an acceptable focal spot only for high ion energies or for currents far below the values assumed in recent HIF power-plant scenarios. Much recent research has, therefore, focused on beam neutralization by electron sources that were neglected in earlier simulations, including emission from walls and the target, photoionization by radiation from the target, and pre-neutralization by a plasma generated along the beam path. The simulations summarized here indicate that these effects can significantly reduce the beam focal-spot size.
Simulation of Chamber Transport for Heavy-Ion Fusion
Sharp, W M; Callahan Miller, D A; Tabak, M; Yu, S S; Peterson, P F; Rose, D V; Welch, D R; Davidson, R C; Kaganovich, I D; Startsev, E; Olson, C L
2002-10-14
Beams for heavy-ion fusion (HIF) are expected to require substantial neutralization in a target chamber. Present targets call for higher beam currents and smaller focal spots than most earlier designs, leading to high space-charge fields. Collisional stripping by the background gas expected in the chamber further increases the beam charge. Simulations with no electron sources other than beam stripping and background-gas ionization show an acceptable focal spot only for high ion energies or for currents far below the values assumed in recent HIF power-plant scenarios. Much recent research has, therefore, focused on beam neutralization by electron sources that were neglected in earlier simulations, including emission from walls and the target, photoionization by radiation from the target, and pre-neutralization by a plasma generated along the beam path. The simulations summarized here indicate that these effects can significantly reduce the beam focal-spot size.
NASA Astrophysics Data System (ADS)
Endres, Stephan; van Hees, Hendrik; Bleicher, Marcus
2016-05-01
We present calculations of dilepton and photon spectra for the energy range Elab=2 A to35 A GeV which will be available for the Compressed Baryonic Matter (CBM) experiment at the future Facility for Proton and Anti-Proton Research (FAIR). The same energy regime will also be covered by phase II of the beam-energy scan at the Relativistic Heavy-Ion Collider (RHIC-BES). Coarse-grained dynamics from microscopic transport calculations of the Ultrarelativistic Quantum Molecular Dynamics (UrQMD) model is used to determine temperature and chemical potentials, which allows for the use of dilepton and photon-emission rates from equilibrium quantum-field-theory calculations. The results indicate that nonequilibrium effects, the presence of baryonic matter, and the creation of a deconfined phase might show up in specific manners in the measurable dilepton invariant-mass spectra and in the photon transverse-momentum spectra. However, as the many influences are difficult to disentangle, we argue that the challenge for future measurements of electromagnetic probes will be to provide a high precision with uncertainties much lower than in previous experiments. Furthermore, a systematic study of the whole energy range covered by CBM at FAIR and RHIC-BES is necessary to discriminate between different effects, which influence the spectra, and to identify possible signatures of a phase transition.
Argonne simulation framework for intelligent transportation systems
Ewing, T.; Doss, E.; Hanebutte, U.; Canfield, T.; Brown-VanHoozer, A.; Tentner, A.
1996-04-01
A simulation framework has been developed which defines a high-level architecture for a large-scale, comprehensive, scalable simulation of an Intelligent Transportation System (ITS). The simulator is designed to run on parallel computers and distributed (networked) computer systems; however, a version for a stand alone workstation is also available. The ITS simulator includes an Expert Driver Model (EDM) of instrumented ``smart`` vehicles with in-vehicle navigation units. The EDM is capable of performing optimal route planning and communicating with Traffic Management Centers (TMC). A dynamic road map data base is sued for optimum route planning, where the data is updated periodically to reflect any changes in road or weather conditions. The TMC has probe vehicle tracking capabilities (display position and attributes of instrumented vehicles), and can provide 2-way interaction with traffic to provide advisories and link times. Both the in-vehicle navigation module and the TMC feature detailed graphical user interfaces that includes human-factors studies to support safety and operational research. Realistic modeling of variations of the posted driving speed are based on human factor studies that take into consideration weather, road conditions, driver`s personality and behavior and vehicle type. The simulator has been developed on a distributed system of networked UNIX computers, but is designed to run on ANL`s IBM SP-X parallel computer system for large scale problems. A novel feature of the developed simulator is that vehicles will be represented by autonomous computer processes, each with a behavior model which performs independent route selection and reacts to external traffic events much like real vehicles. Vehicle processes interact with each other and with ITS components by exchanging messages. With this approach, one will be able to take advantage of emerging massively parallel processor (MPP) systems.
Measurement and simulation of the TRR BNCT beam parameters
NASA Astrophysics Data System (ADS)
Bavarnegin, Elham; Sadremomtaz, Alireza; Khalafi, Hossein; Kasesaz, Yaser; Golshanian, Mohadeseh; Ghods, Hossein; Ezzati, Arsalan; Keyvani, Mehdi; Haddadi, Mohammad
2016-09-01
Recently, the configuration of the Tehran Research Reactor (TRR) thermal column has been modified and a proper thermal neutron beam for preclinical Boron Neutron Capture Therapy (BNCT) has been obtained. In this study, simulations and experimental measurements have been carried out to identify the BNCT beam parameters including the beam uniformity, the distribution of the thermal neutron dose, boron dose, gamma dose in a phantom and also the Therapeutic Gain (TG). To do this, the entire TRR structure including the reactor core, pool, the thermal column and beam tubes have been modeled using MCNPX Monte Carlo code. To measure in-phantom dose distribution a special head phantom has been constructed and foil activation techniques and TLD700 dosimeter have been used. The results show that there is enough uniformity in TRR thermal BNCT beam. TG parameter has the maximum value of 5.7 at the depth of 1 cm from the surface of the phantom, confirming that TRR thermal neutron beam has potential for being used in treatment of superficial brain tumors. For the purpose of a clinical trial, more modifications need to be done at the reactor, as, for example design, and construction of a treatment room at the beam exit which is our plan for future. To date, this beam is usable for biological studies and animal trials. There is a relatively good agreement between simulation and measurement especially within a diameter of 10 cm which is the dimension of usual BNCT beam ports. This relatively good agreement enables a more precise prediction of the irradiation conditions needed for future experiments.
Simulation Studies of Beam-Beam Effects of a Ring-Ring Electron-Ion Collider Based on CEBAF
Yuhong Zhang,Ji Qiang
2009-05-01
The collective beam-beam effect can potentially cause a rapid growth of beam sizes and reduce the luminosity of a collider to an unacceptably low level. The ELIC, a proposed ultra high luminosity electron-ion collider based on CEBAF, employs high repetition rate crab crossing colliding beams with very small bunch transverse sizes and very short bunch lengths, and collides them at up to 4 interaction points with strong final focusing. All of these features can make the beam-beam effect challenging. In this paper, we present simulation studies of the beam-beam effect in ELIC using a self-consistent strong-strong beam-beam simulation code developed at Lawrence Berkeley National Laboratory. This simulation study is used for validating the ELIC design and for searching for an optimal parameter set.
Ostroumov, P. N.; Mustapha, B.; Nolen, J.; Physics
2007-01-01
The Advanced Exotic Beam Laboratory (AEBL) being developed at ANL consists of an 833 MV heavy-ion driver linac capable of producing uranium ions up to 200 MeV/u and protons to 580 MeV with 400 kW beam power. We have designed all accelerator components including a two charge state LEBT, an RFQ, a MEBT, a superconducting linac, a stripper station and chicane. We present the results of an optimized linac design and end-to-end simulations including machine errors and detailed beam loss analysis. The Advanced Exotic Beam Laboratory (AEBL) has been proposed at ANL as a reduced scale of the original Rare Isotope Accelerator (RIA) project with about half the cost but the same beam power. AEBL will address 90% or more of RIA physics but with reduced multi-users capabilities. The focus of this paper is the physics design and beam dynamics simulations of the AEBL driver linac. The reported results are for a multiple charge state U{sup 238} beam.
An improved Green's function for ion beam transport.
Tweed, J; Wilson, J W; Tripathi, R K
2004-01-01
Ion beam transport theory allows testing of material transmission properties in the laboratory environment generated by particle accelerators. This is a necessary step in materials development and evaluation for space use. The approximations used in solving the Boltzmann transport equation for the space setting are often not sufficient for laboratory work and those issues are the main emphasis of the present work. In consequence, an analytic solution of the linear Boltzmann equation is pursued in the form of a Green's function allowing flexibility in application to a broad range of boundary value problems. It has been established that simple solutions can be found for high charge and energy (HZE) ions by ignoring nuclear energy downshifts and dispersion. Such solutions were found to be supported by experimental evidence with HZE ion beams when multiple scattering was added. Lacking from the prior solutions were range and energy straggling and energy downshift with dispersion associated with nuclear events. Recently, we have found global solutions including these effects providing a broader class of HZE ion solutions. PMID:15880918
An Improved Green's Function for Ion Beam Transport
NASA Technical Reports Server (NTRS)
Tweed, J.; Wilson, J. W.; Tripathi, R. K.
2003-01-01
Ion beam transport theory allows testing of material transmission properties in the laboratory environment generated by particle accelerators. This is a necessary step in materials development and evaluation for space use. The approximations used in solving the Boltzmann transport equation for the space setting are often not sufficient for laboratory work and those issues are the main emphasis of the present work. In consequence, an analytic solution of the linear Boltzmann equation is pursued in the form of a Green's function allowing flexibility in application to a broad range of boundary value problems. It has been established that simple solutions can be found for the high charge and energy (HZE) by ignoring nuclear energy downshifts and dispersion. Such solutions were found to be supported by experimental evidence with HZE ion beams when multiple scattering was added. Lacking from the prior solutions were range and energy straggling and energy downshift with dispersion associated with nuclear events. Recently, we have found global solutions including these effects providing a broader class of HZE ion solutions.
An improved Green's function for ion beam transport
NASA Technical Reports Server (NTRS)
Tweed, J.; Wilson, J. W.; Tripathi, R. K.
2004-01-01
Ion beam transport theory allows testing of material transmission properties in the laboratory environment generated by particle accelerators. This is a necessary step in materials development and evaluation for space use. The approximations used in solving the Boltzmann transport equation for the space setting are often not sufficient for laboratory work and those issues are the main emphasis of the present work. In consequence, an analytic solution of the linear Boltzmann equation is pursued in the form of a Green's function allowing flexibility in application to a broad range of boundary value problems. It has been established that simple solutions can be found for high charge and energy (HZE) ions by ignoring nuclear energy downshifts and dispersion. Such solutions were found to be supported by experimental evidence with HZE ion beams when multiple scattering was added. Lacking from the prior solutions were range and energy straggling and energy downshift with dispersion associated with nuclear events. Recently, we have found global solutions including these effects providing a broader class of HZE ion solutions. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.
Design of post linac to driver linac transport beam line in rare isotope accelerator
NASA Astrophysics Data System (ADS)
Kim, Chanmi; Kim, Eun-San
2015-07-01
We investigated the design of a beam transport line connecting the post linac to the driver linac (P2DT) in the Rare Isotope Accelerator (RAON). P2DT beam line is designed by 180° bending scheme to send the radioactive isotope separation on-line (ISOL) beams accelerated in the Linac-3 to Linac-2. The beam line is designed as a 180° bend for the transport of a multi-charge state 132Sn+45,+46,+47 beam. We used the TRACE 3-D, TRACK, and ORBIT codes to design the optics system, which also includes two bunchers and ten sextupole magnets for chromaticity compensation. The transverse emittance growth is minimized by adopting mirror symmetric optics and by correcting second-order aberrations using sextupoles. We report on the multi-charge state beam transport performance of the designed beam line. The main characteristics of the P2DT line are to minimize beam loss and the growth of emittance, and for charge stripping. Beam optics for P2DT is optimized for reducing beam loss and charge stripping. As Linac-3 may accelerate the stable beam and radioactive beam simultaneously, P2DT line also transports the stable beam and radioactive beam simultaneously. Thus, we need a RF switchyard to send the stable beam to the ISOL target and the radioactive beam to the high-energy experimental area in Linac-2 end.
Programmable simulator for beam propagation in turbulent atmosphere.
Rickenstorff, Carolina; Rodrigo, José A; Alieva, Tatiana
2016-05-01
The study of light propagation though the atmosphere is crucial in different areas such as astronomy, free-space communications, remote sensing, etc. Since outdoors experiments are expensive and difficult to reproduce it is important to develop realistic numerical and experimental simulations. It has been demonstrated that spatial light modulators (SLMs) are well-suited for simulating different turbulent conditions in the laboratory. Here, we present a programmable experimental setup based on liquid crystal SLMs for simulation and analysis of the beam propagation through weak turbulent atmosphere. The simulator allows changing the propagation distances and atmospheric conditions without the need of moving optical elements. Its performance is tested for Gaussian and vortex beams. PMID:27137610
Modeling VOC transport in simulated waste drums
Liekhus, K.J.; Gresham, G.L.; Peterson, E.S.; Rae, C.; Hotz, N.J.; Connolly, M.J.
1993-06-01
A volatile organic compound (VOC) transport model has been developed to describe unsteady-state VOC permeation and diffusion within a waste drum. Model equations account for three primary mechanisms for VOC transport from a void volume within the drum. These mechanisms are VOC permeation across a polymer boundary, VOC diffusion across an opening in a volume boundary, and VOC solubilization in a polymer boundary. A series of lab-scale experiments was performed in which the VOC concentration was measured in simulated waste drums under different conditions. A lab-scale simulated waste drum consisted of a sized-down 55-gal metal drum containing a modified rigid polyethylene drum liner. Four polyethylene bags were sealed inside a large polyethylene bag, supported by a wire cage, and placed inside the drum liner. The small bags were filled with VOC-air gas mixture and the VOC concentration was measured throughout the drum over a period of time. Test variables included the type of VOC-air gas mixtures introduced into the small bags, the small bag closure type, and the presence or absence of a variable external heat source. Model results were calculated for those trials where the VOC permeability had been measured. Permeabilities for five VOCs [methylene chloride, 1,1,2-trichloro-1,2,2-trifluoroethane (Freon-113), 1,1,1-trichloroethane, carbon tetrachloride, and trichloroethylene] were measured across a polyethylene bag. Comparison of model and experimental results of VOC concentration as a function of time indicate that model accurately accounts for significant VOC transport mechanisms in a lab-scale waste drum.
Error analysis in post linac to driver linac transport beam line of RAON
NASA Astrophysics Data System (ADS)
Kim, Chanmi; Kim, Eun-San
2016-07-01
We investigated the effects of magnet errors in the beam transport line connecting the post linac to the driver linac (P2DT) in the Rare Isotope Accelerator in Korea (RAON). The P2DT beam line is bent by 180-degree to send the radioactive Isotope Separation On-line (ISOL) beams accelerated in Linac-3 to Linac-2. This beam line transports beams with multi-charge state 132Sn45,46,47. The P2DT beam line includes 42 quadrupole, 4 dipole and 10 sextupole magnets. We evaluate the effects of errors on the trajectory of the beam by using the TRACK code, which includes the translational and the rotational errors of the quadrupole, dipole and sextupole magnets in the beam line. The purpose of this error analysis is to reduce the rate of beam loss in the P2DT beam line. The distorted beam trajectories can be corrected by using six correctors and seven monitors.
Study on the beam transport from the Bio-Nano ECRIS
Uchida, T.; Minezaki, H.; Yoshida, Y.; Oshima, K.; Racz, R.; Biri, S.; Asaji, T.; Kato, Y.
2012-02-15
The beam transport of N{sup +} ion and C{sub 60}{sup +} ion in the Bio-Nano ECRIS with min-B configuration was investigated based on the ion beam profiles. The N{sup +} beam could be focused under the low-beam current conditions. Also the C{sub 60}{sup +} beam could be focused in spite of the large space-charge effect which will lead the divergence of the beam. We confirmed that our beam transport system works well even for the C{sub 60}{sup +} ion beam. We estimated the highest C{sub 60}{sup +} beam current with the focused beam profile by comparing the N{sup +} ion beam.
Simulation of temperature fields in arc and beam welding
NASA Astrophysics Data System (ADS)
Mahrle, A.; Schmidt, J.; Weiss, D.
Heat and mass transfer in arc and beam welding is considered. The main objectives are analysis of the heat transfer in the weld pool and the workpiece and to demonstrate how computer simulation can be used as a tool to predict the temperature distribution as the determining element of the heat effects of welding. Simulation results of two particular welding processes are compared and validated with measurements.
Simulation of space charge compensation in a multibeamlet negative ion beam.
Sartori, E; Maceina, T J; Veltri, P; Cavenago, M; Serianni, G
2016-02-01
Ion beam space charge compensation occurs by cumulating in the beam potential well charges having opposite polarity, usually generated by collisional processes. In this paper we investigate the case of a H(-) ion beam drift, in a bi-dimensional approximation of the NIO1 (Negative Ion Optimization phase 1) negative ion source. H(-) beam ion transport and plasma formation are studied via particle-in-cell simulations. Differential cross sections are sampled to determine the velocity distribution of secondary particles generated by ionization of the residual gas (electrons and slow H2 (+) ions) or by stripping of the beam ions (electrons, H, and H(+)). The simulations include three beamlets of a horizontal section, so that multibeamlet space charge and secondary particle diffusion between separate generation regions are considered, and include a repeller grid biased at various potentials. Results show that after the beam space charge is effectively screened by the secondary plasma in about 3 μs (in agreement with theoretical expectations), a plasma grows across the beamlets with a characteristic time three times longer, and a slight overcompensation of the electric potential is verified as expected in the case of negative ions. PMID:26932089
Simulation of space charge compensation in a multibeamlet negative ion beam
NASA Astrophysics Data System (ADS)
Sartori, E.; Maceina, T. J.; Veltri, P.; Cavenago, M.; Serianni, G.
2016-02-01
Ion beam space charge compensation occurs by cumulating in the beam potential well charges having opposite polarity, usually generated by collisional processes. In this paper we investigate the case of a H- ion beam drift, in a bi-dimensional approximation of the NIO1 (Negative Ion Optimization phase 1) negative ion source. H- beam ion transport and plasma formation are studied via particle-in-cell simulations. Differential cross sections are sampled to determine the velocity distribution of secondary particles generated by ionization of the residual gas (electrons and slow H2+ ions) or by stripping of the beam ions (electrons, H, and H+). The simulations include three beamlets of a horizontal section, so that multibeamlet space charge and secondary particle diffusion between separate generation regions are considered, and include a repeller grid biased at various potentials. Results show that after the beam space charge is effectively screened by the secondary plasma in about 3 μs (in agreement with theoretical expectations), a plasma grows across the beamlets with a characteristic time three times longer, and a slight overcompensation of the electric potential is verified as expected in the case of negative ions.
DART: A simulation code for charged particle beams: Revision 1
White, R.C.; Barr, W.L.; Moir, R.W.
1989-07-31
This paper presents a recently modified version of the 2-D code, DART, which can simulate the behavior of a beam of charged particles whose trajectories are determined by electric and magnetic fields. This code was originally used to design laboratory-scale and full-scale beam direct converters. Since then, its utility has been expanded to allow more general applications. The simulation includes space charge, secondary electrons, and the ionization of neutral gas. A beam can contain up to nine superimposed beamlets of different energy and species. The calculation of energy conversion efficiency and the method of specifying the electrode geometry are described. Basic procedures for using the code are given, and sample input and output fields are shown. 7 refs., 18 figs.
Simulating Electron Cloud Effects in Heavy-Ion Beams
Cohen, R.H.; Friedman, A.; Lund, S.W.; Molvik, A.W.; Azevedo, T.; Vay, J.-L.; Stoltz, P.; Veitzer, S.
2004-08-04
Stray electrons can be introduced in heavy ion fusion accelerators as a result of ionization of ambient gas or gas released from walls due to halo-ion impact, or as a result of secondary-electron emission. We summarize here results from several studies of electron-cloud accumulation and effects: (1) Calculation of the electron cloud produced by electron desorption from computed beam ion loss; the importance of ion scattering is shown; (2) Simulation of the effect of specified electron cloud distributions on ion beam dynamics. We find electron cloud variations that are resonant with the breathing mode of the beam have the biggest impact on the beam (larger than other resonant and random variations), and that the ion beam is surprisingly robust, with an electron density several percent of the beam density required to produce significant beam degradation in a 200-quadrupole system. We identify a possible instability associated with desorption and resonance with the breathing mode. (3) Preliminary investigations of a long-timestep algorithm for electron dynamics in arbitrary magnetic fields.
RIAPMTQ/Impact : beam-dynamics simulation tool for RIA.
Wangler, T. P.; Billen, J. H.; Garnett, R. W.; Qiang, J.; Ryne, R.; Crandall, K. R.; Ostroumov, P.; Aseev, V. N.; Mustapha, B.; York, R. C.; Wu, X.; Zhao, Q.; Gorelov, D.; Doleans, M.; Physics; LANL; Tech Source; Michigan State Univ.
2006-01-01
We have developed a pair of multiparticle beam dynamics codes for end-to-end computer simulations of the proposed RIA heavy-ion driver linac. The two codes are: (1) an adaptation of PARMTEQ called RIAPMTQ for the normal-conducting-linac front end, and (2) IMPACT for the superconducting linac. The codes run on a PC as well as on parallel supercomputing platforms such as NERSC at LBNL. The parallel capability allows us to run simulations with large numbers of macroparticles for the computation of beam halo and beam-losses. The codes are being benchmarked for rms beam properties against previously existing codes at ANL and MSU. The work is being performed by a collaboration including LANL, LBNL, ANL, and Michigan State University (MSU). In this paper we present an overview, the status of the work, comparison of simulation results from RIAPMTQ and the ANL code TRACK for the ANL front-end design, and the first RIAPMTQ/IMPACT end-to-end multiprocessor simulation for the MSU design.
Earth Model with Laser Beam Simulating Seismic Ray Paths.
ERIC Educational Resources Information Center
Ryan, John Arthur; Handzus, Thomas Jay, Jr.
1988-01-01
Described is a simple device, that uses a laser beam to simulate P waves. It allows students to follow ray paths, reflections and refractions within the earth. Included is a set of exercises that lead students through the steps by which the presence of the outer and inner cores can be recognized. (Author/CW)
Transport simulation of ITER scenarios with driven burn
NASA Astrophysics Data System (ADS)
Becker, G.
2000-08-01
Transport in the ignited reduced cost ITER devices IAM (Intermediate Aspect Ratio Machine) and LAM (Low Aspect Ratio Machine) is explored by self-consistent simulations using a special version of the 1.5 dimensional BALDUR predictive transport code and applying empirical transport coefficients. The main objective of the study is to determine the thermal energy confinement time τE,r required for operation at the design parameters. It is found that the τE,r value of the inductive IAM (with a helium fraction of 9%) is 3.3 s with argon seeding compared with τE,p = 3.0 s predicted by global scalings. For operation at τE,r = τE,p the value of Q = Pfus/Pb must be reduced from 10 to 6.1, where Pfus is the fusion power and Pb is the beam power. The necessary radiative loss from closed flux surfaces is reached in the argon scenario at high and low separatrix densities. The assumption of flat density profiles and high edge densities is supported by simulations using a new scaling law for the anomalous inward drift velocity. A study of the advanced tokamak scenario of IAM resulting in an estimate of the required energy confinement time is also carried out. Simulation of the inductive LAM argon scenario yields τE,r = 4.0 s compared with τE,p = 3.9 s predicted by global scalings. Here operation at τE,p demands a Q value of 8.7.
Operation of the intensity monitors in beam transport lines at Fermilab during Run II¹
Crisp, J.; Fellenz, B.; Fitzgerald, J.; Heikkinen, D.; Ibrahim, M. A.
2011-10-06
The intensity of charged particle beams at Fermilab must be kept within pre-determined safety and operational envelopes in part by assuring all beam within a few percent has been transported from any source to destination. Beam instensity monitors with toroidial pickups provide such beam intensity measurements in the transport lines between accelerators at FNAL. With Run II, much effort was made to continually improve the resolution and accuracy of the system.
NASA Astrophysics Data System (ADS)
Gammino, S.; Ciavola, G.; Celona, L.; Andò, L.; Passarello, S.; Zhang, X. Zh.; Spädtke, P.; Winkler, M.
2004-05-01
A study of the design of extraction and transport system for high intensity beams that will be produced by the next generation electron cyclotron resonance ion source (ECRIS) was carried out in the frame of a European collaboration devoted to the definition of the main parameters of third generation ECRIS. High intensity production tests carried out in the previous years at INFN-LNS have shown evidence for the need to review the main concepts of the beam analysis and transport when high currents of low energy highly charged ions are extracted from the source. The transport of such low energy beams becomes critical as soon as the total current exceeds a few mA. The study reported here is based on the calculated parameters for the GyroSERSE source and the computer simulations have been carried out to obtain low emittance beams. The design of the extraction system was carried out by means of the KOBRA (three dimensional) code. The study of the beam line has been carried out with the codes GIOS, GICO, and TRANSPORT by taking into account both the phase space growth due to space charge and to the aberrations inside the magnets. The description of some different beam line options will be also given.
Grote, D.P.
1994-11-01
Heavy ion fusion requires injection, transport and acceleration of high current beams. Detailed simulation of such beams requires fully self-consistent space charge fields and three dimensions. WARP3D, developed for this purpose, is a particle-in-cell plasma simulation code optimized to work within the framework of an accelerator`s lattice of accelerating, focusing, and bending elements. The code has been used to study several test problems and for simulations and design of experiments. Two applications are drift compression experiments on the MBE-4 facility at LBL and design of the electrostatic quadrupole injector for the proposed ILSE facility. With aggressive drift compression on MBE-4, anomalous emittance growth was observed. Simulations carried out to examine possible causes showed that essentially all the emittance growth is result of external forces on the beam and not of internal beam space-charge fields. Dominant external forces are the dodecapole component of focusing fields, the image forces on the surrounding pipe and conductors, and the octopole fields that result from the structure of the quadrupole focusing elements. Goal of the design of the electrostatic quadrupole injector is to produce a beam of as low emittance as possible. The simulations show that the dominant effects that increase the emittance are the nonlinear octopole fields and the energy effect (fields in the axial direction that are off-axis). Injectors were designed that minimized the beam envelope in order to reduce the effect of the nonlinear fields. Alterations to the quadrupole structure that reduce the nonlinear fields further were examined. Comparisons were done with a scaled experiment resulted in very good agreement.
Reactive transport benchmarks for subsurface environmental simulation
Steefel, Carl I.; Yabusaki, Steven B.; Mayer, K. U.
2015-06-01
Over the last 20 years, we have seen firsthand the evolution of multicomponent reactive transport modeling and the expanding range and increasing complexity of subsurface applications it is being used to address. There is a growing reliance on reactive transport modeling (RTM) to address some of the most compelling issues facing our planet: climate change, nuclear waste management, contaminant remediation, and pollution prevention. While these issues are motivating the development of new and improved capabilities for subsurface environmental modeling using RTM (e.g., biogeochemistry from cell-scale physiology to continental-scale terrestrial ecosystems, nonisothermal multiphase conditions, coupled geomechanics), there remain longstanding challenges in characterizing the natural variability of hydrological, biological, and geochemical properties in subsurface environments and limited success in transferring models between sites and across scales. An equally important trend over the last 20 years is the evolution of modeling from a service sought out after data has been collected to a multifaceted research approach that provides (1) an organizing principle for characterization and monitoring activities; (2) a systematic framework for identifying knowledge gaps, developing and integrating new knowledge; and (3) a mechanistic understanding that represents the collective wisdom of the participating scientists and engineers. There are now large multidisciplinary projects where the research approach is model-driven, and the principal product is a holistic predictive simulation capability that can be used as a test bed for alternative conceptualizations of processes, properties, and conditions. Much of the future growth and expanded role for RTM will depend on its continued ability to exploit technological advancements in the earth and environmental sciences. Advances in measurement technology, particularly in molecular biology (genomics), isotope fractionation, and high
Simulations and observations of heating of auroral ion beams
NASA Technical Reports Server (NTRS)
Winglee, R. M.; Dusenbery, P. B.; Collin, H. L.; Lin, C. S.; Persoon, A. M.
1989-01-01
Two-dimensional three-velocity electrostatic particle simulations were used to determine the nonlinear evolution of the distributions of auroral ion beams and thereby to determine quantitatively signatures in the ion distributions produced by the ion-ion instability for a variety of plasma conditions in the auroral zone. The signatures determined from these simulations were compared with observations from DE 1, making it possible to characterize semiquantitatively the heating of the ionospheric ions, and to investigate the causes of variability seen in the observations of Reiff et al. (1988). A comparison of the simulation with observations showed features consistent with heating via the ion-ion instability including perpendicular heating in the supersonic regime and parallel heating in the subsonic regime, and a change in the heating between these regimes as the ratio of the H(+) beam speed to the local sound speed decreases.
Validation experiments for LBM simulations of electron beam melting
NASA Astrophysics Data System (ADS)
Ammer, Regina; Rüde, Ulrich; Markl, Matthias; Jüchter, Vera; Körner, Carolin
2014-05-01
This paper validates three-dimensional (3D) simulation results of electron beam melting (EBM) processes by comparing experimental and numerical data. The physical setup is presented which is discretized by a 3D thermal lattice Boltzmann method (LBM). An experimental process window is used for the validation depending on the line energy injected into the metal powder bed and the scan velocity of the electron beam. In the process window, the EBM products are classified into the categories, porous, good and swelling, depending on the quality of the surface. The same parameter sets are used to generate a numerical process window. A comparison of numerical and experimental process windows shows a good agreement. This validates the EBM model and justifies simulations for future improvements of the EBM processes. In particular, numerical simulations can be used to explain future process window scenarios and find the best parameter set for a good surface quality and dense products.
Particle Simulations for Electron Beam-Plasma Interactions
NASA Astrophysics Data System (ADS)
Zhou, Guo-cheng; G, Zhou C.; Li, Yang; Cao, Jin-bin; J, Cao B.; Wang, Xue-yi; X, Wang Y.
1998-12-01
The computer simulations of high-frequency instabilities excited by the high density electron beam and their nonlinear effect are presented. One-dimensional electromagnetic particle simulations are performed with different values of the electron beam-to-plasma density ratio. The results show that for the high electron beam-to-background plasma density ratio, all the Langmuir waves and two electromagnetic waves with left-hand and right-hand circular polarizations (i.e., the "L-O mode" and the "R-X mode") propagating parallel to the magnetic field can be generated and the maximum values of wave electric fields are nearly the same. The electron beam and background plasma are diffused and a part of energetic background electrons are obviously accelerated by the wave-particle interactions. The heating of the beam and background plasma is mainly due to the electrostatic (Langmuir) wave-particle interactions, but the accelerations of a part of energetic background electrons may be mainly due to the electromagnetic wave-particle interactions.
Simulating Radiation Transport in Curved Spacetimes
NASA Astrophysics Data System (ADS)
Endeve, Eirik; Hauck, Cory; Xing, Yulong; Cardall, Christian; Mezzacappa, Anthony
2014-03-01
We are developing methods for simulation of radiation transport in systems governed by strong gravity (e.g., neutrino transport in core-collapse supernovae). By employing conservative formulations of the general relativistic Boltzmann equation, we aim to develop methods that are (i) high-order accurate for computational efficiency; (ii) robust in the sense that the phase space density f preserves the maximum principle of the physical model (f ∈ [ 0 , 1 ] for fermions); and (iii) applicable to curvilinear coordinate systems to accommodate curved spacetimes, which result in gravity-induced frequency shift and angular aberration. Our approach is based on the Runge-Kutta discontinuous Galerkin method, which has many attractive properties, including high-order accuracy on a compact stencil. We present the physical model, describe our numerical methods, and show results from implementations in spherical and axial symmetry. Our tests show that the method is high-order accurate and strictly preserves the maximum principle on f. We also demonstrate the ability of our method to accurately include effects of a strong gravitational field.
NASA Astrophysics Data System (ADS)
Zeng, Han; Xiong, Yongqian; Pei, Yuanji
2014-11-01
The transport line used in a terahertz FEL device has to transport electron beam through the entire system efficiently and meet the requirements of the beam parameters at the undulator entrance. Due to space limitations, the size of the magnets (five quadrupoles and two bending magnets) employed in the transport line was limited, and some devices were densely packed. In this paper, analyses of the effect of fringe fields and magnetic interference of magnets are presented. 3D models of these magnets are built and their linear optical properties are compared with those obtained by hard edge models. The results indicated that the effects of these factors are significant and they would cause a mismatch of the beam at the exit of the transport line under the preliminary lattice design. To solve this problem, the beam was re-matched using the particle swarm optimization algorithm.
Charge breeding simulations for radioactive ion beam production
Variale, V.; Raino, A. C.; Clauser, T.
2012-02-15
The charge breeding technique is used for radioactive ion beam (RIB) production in order of optimizing the re-acceleration of the radioactive element ions produced by a primary beam in a thick target. Charge breeding is achieved by means of a device capable of increasing the ion charge state from 1+ to a desired value n+. In order to get high intensity RIB, experiments with charge breeding of very high efficiency could be required. To reach this goal, the charge breeding simulation could help to optimize the high charge state production efficiency by finding more proper parameters for the radioactive 1+ ions. In this paper a device based on an electron beam ion source (EBIS) is considered. In order to study that problem, a code already developed for studying the ion selective containment in an EBIS with RF quadrupoles, BRICTEST, has been modified to simulate the ion charge state breeding rate for different 1+ ion injection conditions. Particularly, the charge breeding simulations for an EBIS with a hollow electron beam have been studied.
A low Earth orbit molecular beam space simulation facility
NASA Technical Reports Server (NTRS)
Cross, J. B.
1984-01-01
A brief synopsis of the low Earth orbit (LEO) satellite environment is presented including neutral and ionic species. Two ground based atomic and molecular beam instruments are described which are capable of simulating the interaction of spacecraft surfaces with the LEO environment and detecting the results of these interactions. The first detects mass spectrometrically low level fluxes of reactively and nonreactively surface scattered species as a function of scattering angle and velocity while the second ultrahigh velocity (UHV) molecular beam, laser induced fluorescence apparatus is capable of measuring chemiluminescence produced by either gas phase or gas-surface interactions. A number of proposed experiments are described.
Modeling and simulation of the beam steering unit
NASA Astrophysics Data System (ADS)
Feng, Jiayun; Li, Xiaoping; He, Xin; Wang, Jinchun
2015-03-01
Production lithography is undergoing a technology shift, and the requirements of beam delivery system (BDS) are increasing which also raises the precision requirements of the beam steering units (BSU) in BDS. In essence, the BSU is a two rotational degree of freedom platform. In this paper, a BSU based on 3-RPS flexure parallel mechanism is proposed. By analyzing the relationship between the unit's dimensions and mechanics, a mathematical model is built. Then the BSU with a balance between lower stress of the flexure hinges and higher accuracy of the unit can be got by optimizing the dimensions with the mathematical model. Finally a simulation is conducted to verify the design.
Transverse centroid oscillations in solenoidially focused beam transport lattices
Lund, Steven M.; Wootton, Christopher J.; Lee, Edward P.
2008-08-01
Linear equations of motion are derived that describe small-amplitude centroid oscillations induced by displacement and rotational misalignments of the focusing solenoids in the transport lattice, dipole steering elements, and initial centroid offset errors. These equations are analyzed in a local rotating Larmor frame to derive complex-variable"alignment functions" and"bending functions" that efficiently describe the characteristics of the centroid oscillations induced by mechanical misalignments of the solenoids and dipole steering elements. The alignment and bending functions depend only on properties of the ideal lattice in the absence of errors and steering and have associated expansion amplitudes set by the misalignments and steering fields. Applications of this formulation are presented for statistical analysis of centroid deviations, calculation of actual lattice misalignments from centroid measurements, and optimal beam steering.
Transverse Centroid Oscillations in Solenoidially Focused Beam Transport Lattices
Lund, S M; Wootton, C J; Lee, E P
2008-08-01
Linear equations of motion are derived that describe small-amplitude centroid oscillations induced by displacement and rotational misalignments of the focusing solenoids in the transport lattice, dipole steering elements, and initial centroid offset errors. These equations are analyzed in a local rotating Larmor frame to derive complex-variable 'alignment functions' and 'bending functions' that efficiently describe the characteristics of the centroid oscillations induced by mechanical misalignments of the solenoids and dipole steering elements. The alignment and bending functions depend only on properties of the ideal lattice in the absence of errors and steering and have associated expansion amplitudes set by the misalignments and steering fields. Applications of this formulation are presented for statistical analysis of centroid deviations, calculation of actual lattice misalignments from centroid measurements, and optimal beam steering.
A Transport Model for Nuclear Reactions Induced by Radioactive Beams
Li Baoan; Chen Liewen; Das, Champak B.; Das Gupta, Subal; Gale, Charles; Ko, C.M.; Yong, G.-C.; Zuo Wei
2005-10-14
Major ingredients of an isospin and momentum dependent transport model for nuclear reactions induced by radioactive beams are outlined. Within the IBUU04 version of this model we study several experimental probes of the equation of state of neutron-rich matter, especially the density dependence of the nuclear symmetry energy. Comparing with the recent experimental data from NSCL/MSU on isospin diffusion, we found a nuclear symmetry energy of Esym({rho}) {approx_equal} 31.6({rho}/{rho}0)1.05 at subnormal densities. Predictions on several observables sensitive to the density dependence of the symmetry energy at supranormal densities accessible at GSI and the planned Rare Isotope Accelerator (RIA) are also made.
Molecular dynamics simulations of microscale fluid transport
Wong, C.C.; Lopez, A.R.; Stevens, M.J.; Plimpton, S.J.
1998-02-01
Recent advances in micro-science and technology, like Micro-Electro-Mechanical Systems (MEMS), have generated a group of unique liquid flow problems that involve characteristic length scales of a Micron. Also, in manufacturing processes such as coatings, current continuum models are unable to predict microscale physical phenomena that appear in these non-equilibrium systems. It is suspected that in these systems, molecular-level processes can control the interfacial energy and viscoelastic properties at the liquid/solid boundary. A massively parallel molecular dynamics (MD) code has been developed to better understand microscale transport mechanisms, fluid-structure interactions, and scale effects in micro-domains. Specifically, this MD code has been used to analyze liquid channel flow problems for a variety of channel widths, e.g. 0.005-0.05 microns. This report presents results from MD simulations of Poiseuille flow and Couette flow problems and addresses both scaling and modeling issues. For Poiseuille flow, the numerical predictions are compared with existing data to investigate the variation of the friction factor with channel width. For Couette flow, the numerical predictions are used to determine the degree of slip at the liquid/solid boundary. Finally, the results also indicate that shear direction with respect to the wall lattice orientation can be very important. Simulation results of microscale Couette flow and microscale Poiseuille flow for two different surface structures and two different shear directions will be presented.
Accelerating Subsurface Transport Simulation on Heterogeneous Clusters
Villa, Oreste; Gawande, Nitin A.; Tumeo, Antonino
2013-09-23
Reactive transport numerical models simulate chemical and microbiological reactions that occur along a flowpath. These models have to compute reactions for a large number of locations. They solve the set of ordinary differential equations (ODEs) that describes the reaction for each location through the Newton-Raphson technique. This technique involves computing a Jacobian matrix and a residual vector for each set of equation, and then solving iteratively the linearized system by performing Gaussian Elimination and LU decomposition until convergence. STOMP, a well known subsurface flow simulation tool, employs matrices with sizes in the order of 100x100 elements and, for numerical accuracy, LU factorization with full pivoting instead of the faster partial pivoting. Modern high performance computing systems are heterogeneous machines whose nodes integrate both CPUs and GPUs, exposing unprecedented amounts of parallelism. To exploit all their computational power, applications must use both the types of processing elements. For the case of subsurface flow simulation, this mainly requires implementing efficient batched LU-based solvers and identifying efficient solutions for enabling load balancing among the different processors of the system. In this paper we discuss two approaches that allows scaling STOMP's performance on heterogeneous clusters. We initially identify the challenges in implementing batched LU-based solvers for small matrices on GPUs, and propose an implementation that fulfills STOMP's requirements. We compare this implementation to other existing solutions. Then, we combine the batched GPU solver with an OpenMP-based CPU solver, and present an adaptive load balancer that dynamically distributes the linear systems to solve between the two components inside a node. We show how these approaches, integrated into the full application, provide speed ups from 6 to 7 times on large problems, executed on up to 16 nodes of a cluster with two AMD Opteron 6272
Parallel Simulation Algorithms for the Three Dimensional Strong-Strong Beam-Beam Interaction
Kabel, A.C.; /SLAC
2008-03-17
The strong-strong beam-beam effect is one of the most important effects limiting the luminosity of ring colliders. Little is known about it analytically, so most studies utilize numeric simulations. The two-dimensional realm is readily accessible to workstation-class computers (cf.,e.g.,[1, 2]), while three dimensions, which add effects such as phase averaging and the hourglass effect, require vastly higher amounts of CPU time. Thus, parallelization of three-dimensional simulation techniques is imperative; in the following we discuss parallelization strategies and describe the algorithms used in our simulation code, which will reach almost linear scaling of performance vs. number of CPUs for typical setups.
Barbisan, M. Zaniol, B.; Pasqualotto, R.
2014-11-15
A test facility for the development of the neutral beam injection system for ITER is under construction at Consorzio RFX. It will host two experiments: SPIDER, a 100 keV H{sup −}/D{sup −} ion RF source, and MITICA, a prototype of the full performance ITER injector (1 MV, 17 MW beam). A set of diagnostics will monitor the operation and allow to optimize the performance of the two prototypes. In particular, beam emission spectroscopy will measure the uniformity and the divergence of the fast particles beam exiting the ion source and travelling through the beam line components. This type of measurement is based on the collection of the H{sub α}/D{sub α} emission resulting from the interaction of the energetic particles with the background gas. A numerical model has been developed to simulate the spectrum of the collected emissions in order to design this diagnostic and to study its performance. The paper describes the model at the base of the simulations and presents the modeled H{sub α} spectra in the case of MITICA experiment.
Modelling and simulation of beam formation in electron guns
NASA Astrophysics Data System (ADS)
Sabchevski, S.; Mladenov, G.; Titov, A.; Barbarich, I.
1996-02-01
This paper describes a new PC version of the software package GUN-EBT for computer simulation of beam formation in rotationally symmetric electron guns with thermionic cathodes. It is based on a self-consistent physical model which takes into account the beam space charge and the initial velocities effects. The theoretical framework used for both the formulation of the model and for the interpretation of the results of numerical experiments is the formalism of the charged particle dynamics in phase space. This enables not only a trajectory analysis (ray tracing) but also a phase-space analysis of beams to be performed. The package can be used as an effective tool for computer aided design and optimization of electron guns in various electron-optical systems. The operation of the package is illustrated with a typical example.
Fermilab Booster Transition Crossing Simulations and Beam Studies
Bhat, C. M.; Tan, C. Y.
2016-01-01
The Fermilab Booster accelerates beam from 400 MeV to 8 GeV at 15 Hz. In the PIP (Proton Improvement Plan) era, it is required that Booster deliver 4.2 x $10^{12}$ protons per pulse to extraction. One of the obstacles for providing quality beam to the users is the longitudinal quadrupole oscillation that the beam suffers from right after transition. Although this oscillation is well taken care of with quadrupole dampers, it is important to understand the source of these oscillations in light of the PIP II requirements that require 6.5 x $10^{12}$ protons per pulse at extraction. This paper explores the results from machine studies, computer simulations and solutions to prevent the quadrupole oscillations after transition.
Integrated simulations for ion beam assisted fast ignition
NASA Astrophysics Data System (ADS)
Sakagami, H.; Johzaki, T.; Sunahara, A.; Nagatomo, H.
2016-03-01
Although the energy conversion efficiency from the heating laser to fast electrons is high, the coupling efficiency from fast electrons to the core is estimated to be very low due to large divergence angle of fast electrons in fast ignition experiments at ILE, Osaka University. To mitigate this problem, a plastic thin film or low-density foam, which can generate not only proton (H+) but also carbon (C6+) beams, is combined with currently used cone-guided targets and additional core heating by ions is expected. According to integrated simulations, it is found that these ion beams can enhance the core heating by 20∼60% and it shows a possibility of ion beam assisted fast ignition.
Simulation of dynamics of beam structures with bolted joints using adjusted Iwan beam elements
NASA Astrophysics Data System (ADS)
Song, Y.; Hartwigsen, C. J.; McFarland, D. M.; Vakakis, A. F.; Bergman, L. A.
2004-05-01
Mechanical joints often affect structural response, causing localized non-linear stiffness and damping changes. As many structures are assemblies, incorporating the effects of joints is necessary to produce predictive finite element models. In this paper, we present an adjusted Iwan beam element (AIBE) for dynamic response analysis of beam structures containing joints. The adjusted Iwan model consists of a combination of springs and frictional sliders that exhibits non-linear behavior due to the stick-slip characteristic of the latter. The beam element developed is two-dimensional and consists of two adjusted Iwan models and maintains the usual complement of degrees of freedom: transverse displacement and rotation at each of the two nodes. The resulting element includes six parameters, which must be determined. To circumvent the difficulty arising from the non-linear nature of the inverse problem, a multi-layer feed-forward neural network (MLFF) is employed to extract joint parameters from measured structural acceleration responses. A parameter identification procedure is implemented on a beam structure with a bolted joint. In this procedure, acceleration responses at one location on the beam structure due to one known impulsive forcing function are simulated for sets of combinations of varying joint parameters. A MLFF is developed and trained using the patterns of envelope data corresponding to these acceleration histories. The joint parameters are identified through the trained MLFF applied to the measured acceleration response. Then, using the identified joint parameters, acceleration responses of the jointed beam due to a different impulsive forcing function are predicted. The validity of the identified joint parameters is assessed by comparing simulated acceleration responses with experimental measurements. The capability of the AIBE to capture the effects of bolted joints on the dynamic responses of beam structures, and the efficacy of the MLFF parameter
Beam Transport Devices for the 10 kW IR Free Electron Laser
Lawrence Dillon-Townes; Michael Bevins; David Kashy; Stephanie Slachtouski; Ronald Lassiter; George Neil; Michelle D. Shinn; Joseph Gubeli; Christopher Behre; David Douglas; David W. Waldman; George Biallas; Lawrence Munk; Christopher Gould
2005-05-01
Beam transport components for the 10kW IR Free Electron Laser (FEL) at Thomas Jefferson National Accelerator Facility (Jefferson Lab) were designed to manage (1) electron beam transport and (2) photon beam transport. An overview of the components will be presented in this paper. The electron beam transport components were designed to address RF heating, maintain an accelerator transport vacuum of 1 x 10{sup -8} torr, deliver photons to the optical cavity, and provide 50 kW of beam absorption during the energy recovery process. The components presented include a novel shielded bellows, a novel zero length beam clipper, a one decade differential pumping station with a 7.62 cm (3.0 inch) aperture, and a 50 kW beam dump. The photon beam transport components were designed to address the management of photons delivered by the accelerator transport. The optical cavity manages the photons and optical transport delivers the 10 kW of laser power to experimental labs. The optical cavity component presented is a unique high reflector vessel and the optical transport component presented is a turning mirror cassette.
Solenoidal Fields for Ion Beam Transport and Focusing
Lee, Edward P.; Leitner, Matthaeus
2007-11-01
In this report we calculate time-independent fields of solenoidal magnets that are suitable for ion beam transport and focusing. There are many excellent Electricity and Magnetism textbooks that present the formalism for magnetic field calculations and apply it to simple geometries [1-1], but they do not include enough relevant detail to be used for designing a charged particle transport system. This requires accurate estimates of fringe field aberrations, misaligned and tilted fields, peak fields in wire coils and iron, external fields, and more. Specialized books on magnet design, technology, and numerical computations [1-2] provide such information, and some of that is presented here. The AIP Conference Proceedings of the US Particle Accelerator Schools [1-3] contain extensive discussions of design and technology of magnets for ion beams - except for solenoids. This lack may be due to the fact that solenoids have been used primarily to transport and focus particles of relatively low momenta, e.g. electrons of less than 50 MeV and protons or H- of less than 1.0 MeV, although this situation may be changing with the commercial availability of superconducting solenoids with up to 20T bore field [1-4]. Internal reports from federal laboratories and industry treat solenoid design in detail for specific applications. The present report is intended to be a resource for the design of ion beam drivers for Inertial Fusion Energy [1-5] and Warm Dense Matter experiments [1-6], although it should also be useful for a broader range of applications. The field produced by specified currents and material magnetization can always be evaluated by solving Maxwell's equations numerically, but it is also desirable to have reasonably accurate, simple formulas for conceptual system design and fast-running beam dynamics codes, as well as for general understanding. Most of this report is devoted to such formulas, but an introduction to the Tosca{copyright} code [1-7] and some numerical
NASA Astrophysics Data System (ADS)
Wang, Qian; Li, Bincheng
2015-12-01
In this paper, photocarrier radiometry (PCR) technique with multiple pump beam sizes is employed to determine simultaneously the electronic transport parameters (the carrier lifetime, the carrier diffusion coefficient, and the front surface recombination velocity) of silicon wafers. By employing the multiple pump beam sizes, the influence of instrumental frequency response on the multi-parameter estimation is totally eliminated. A nonlinear PCR model is developed to interpret the PCR signal. Theoretical simulations are performed to investigate the uncertainties of the estimated parameter values by investigating the dependence of a mean square variance on the corresponding transport parameters and compared to that obtained by the conventional frequency-scan method, in which only the frequency dependences of the PCR amplitude and phase are recorded at single pump beam size. Simulation results show that the proposed multiple-pump-beam-size method can improve significantly the accuracy of the determination of the electronic transport parameters. Comparative experiments with a p-type silicon wafer with resistivity 0.1-0.2 Ω.cm are performed, and the electronic transport properties are determined simultaneously. The estimated uncertainties of the carrier lifetime, diffusion coefficient, and front surface recombination velocity are approximately ±10.7%, ±8.6%, and ±35.4% by the proposed multiple-pump-beam-size method, which is much improved than ±15.9%, ±29.1%, and >±50% by the conventional frequency-scan method. The transport parameters determined by the proposed multiple-pump-beam-size PCR method are in good agreement with that obtained by a steady-state PCR imaging technique.
Wang, Qian; Li, Bincheng
2015-12-07
In this paper, photocarrier radiometry (PCR) technique with multiple pump beam sizes is employed to determine simultaneously the electronic transport parameters (the carrier lifetime, the carrier diffusion coefficient, and the front surface recombination velocity) of silicon wafers. By employing the multiple pump beam sizes, the influence of instrumental frequency response on the multi-parameter estimation is totally eliminated. A nonlinear PCR model is developed to interpret the PCR signal. Theoretical simulations are performed to investigate the uncertainties of the estimated parameter values by investigating the dependence of a mean square variance on the corresponding transport parameters and compared to that obtained by the conventional frequency-scan method, in which only the frequency dependences of the PCR amplitude and phase are recorded at single pump beam size. Simulation results show that the proposed multiple-pump-beam-size method can improve significantly the accuracy of the determination of the electronic transport parameters. Comparative experiments with a p-type silicon wafer with resistivity 0.1–0.2 Ω·cm are performed, and the electronic transport properties are determined simultaneously. The estimated uncertainties of the carrier lifetime, diffusion coefficient, and front surface recombination velocity are approximately ±10.7%, ±8.6%, and ±35.4% by the proposed multiple-pump-beam-size method, which is much improved than ±15.9%, ±29.1%, and >±50% by the conventional frequency-scan method. The transport parameters determined by the proposed multiple-pump-beam-size PCR method are in good agreement with that obtained by a steady-state PCR imaging technique.
SIMULATION OF INTENSE BEAMS FOR HEAVY ION FUSION
Friedman, A
2004-06-10
Computer simulations of intense ion beams play a key role in the Heavy Ion Fusion research program. Along with analytic theory, they are used to develop future experiments, guide ongoing experiments, and aid in the analysis and interpretation of experimental results. They also afford access to regimes not yet accessible in the experimental program. The U.S. Heavy Ion Fusion Virtual National Laboratory and its collaborators have developed state-of-the art computational tools, related both to codes used for stationary plasmas and to codes used for traditional accelerator applications, but necessarily differing from each in important respects. These tools model beams in varying levels of detail and at widely varying computational cost. They include moment models (envelope equations and fluid descriptions), particle-in-cell methods (electrostatic and electromagnetic), nonlinear-perturbative descriptions (''{delta}f''), and continuum Vlasov methods. Increasingly, it is becoming clear that it is necessary to simulate not just the beams themselves, but also the environment in which they exist, be it an intentionally-created plasma or an unwanted cloud of electrons and gas. In this paper, examples of the application of simulation tools to intense ion beam physics are presented, including support of present-day experiments, fundamental beam physics studies, and the development of future experiments. Throughout, new computational models are described and their utility explained. These include Mesh Refinement (and its dynamic variant, Adaptive Mesh Refinement); improved electron cloud and gas models, and an electron advance scheme that allows use of larger time steps; and moving-mesh and adaptive-mesh Vlasov methods.
Three-Dimensional Quasistatic Model for High Brightness Beam Dynamics Simulation
Qiang, Ji; Lidia, S.; Ryne, R.D.; Limborg-Deprey, C.; /SLAC
2006-06-19
In this paper, we present a three-dimensional quasistatic model for high brightness beam dynamics simulation in rf/dc photoinjectors, rf linacs, and similar devices on parallel computers. In this model, electrostatic space-charge forces within a charged particle beam are calculated self-consistently at each time step by solving the three-dimensional Poisson equation in the beam frame and then transforming back to the laboratory frame. When the beam has a large energy spread, it is divided into a number of energy bins or slices so that the space-charge forces are calculated from the contribution of each bin and summed together. Image-charge effects from conducting photocathode are also included efficiently using a shifted-Green function method. For a beam with large aspect ratio, e.g., during emission, an integrated Green function method is used to solve the three-dimensional Poisson equation. Using this model, we studied beam transport in one Linac Coherent Light Sources photoinjector design through the first traveling wave linac with initial misalignment with respect to the accelerating axis.
Transport simulations of ohmic ignition experiment: IGNITEX
Uckan, N.A.; Howe, H.C.
1987-12-01
The IGNITEX device, proposed by Rosenbluth et al., is a compact, super-high-field, high-current, copper-coil tokamak envisioned to reach ignition with ohmic (OH) heating alone. Several simulations of IGNITEX were made with a 0-D global model and with the 1-D PROCTR transport code. It is shown that OH ignition is a sensitive function of the assumptions about density profile, wall reflectivity of synchrotron radiation, impurity radiation, plasma edge conditions, and additional anomalous losses. In IGNITEX, OH ignition is accessible with nearly all scalings based on favorable OH confinement (such as neo-Alcator). Also, OH ignition appears to be accessible for most (not all) L-mode scalings (such as Kaye-Goldston), provided that the density profile is not too broad (parabolic or more peaked profiles are needed), Z/sub eff/ is not too large, and anomalous radiation and alpha losses and/or other enhanced transport losses (eta/sub i/ modes, edge convective energy losses, etc.) are not present. In IGNITEX, because the figure-of-merit parameters are large, ignition can be accessed (either with OH heating alone or with the aid of a small amount of auxiliary power) at relatively low beta, far from stability limits. Once the plasma is ignited, thermal runaway is prevented naturally by a combination of increased synchrotron radiation, burnout of the fuel in the plasma core and replacement by thermal alphas, and the reduction in the thermal plasma confinement assumed in L-mode-like scalings. 12 refs., 5 figs., 1 tab.
Investigation of Charge Gain in Diamond Electron Beam Amplifiers Via 3D Simulations
Busby,R.; Rao,T.; D.A. Dimitrov, J.R. Cary, I. Ben-Zvi, X. Chang, J. Keister, E. Muller, J. Smedley, Q. Wu
2009-05-04
A promising new concept of a diamond amplified photocathode for generation of high-current, high-brightness, and low thermal emittance electron beams was recently proposed and is currently under active development. To better understand the different effects involved in the generation ofelectron beams from diamond, we have been developing models (within the VORPAL computational framework) to simulate secondary electron generation and charge transport. The currently implemented models include inelastic scattering of electrons and holes for generation of electron-hole pairs, elastic, phonon, and charge impurity scattering. We will present results from 3D VORPAL simulations with these capabilities on charge gain as a function of primary electron energy and applied electric field. Moreover, we consider effects of electron and hole cloud expansion (initiated by primary electrons) and separation in a surface domain of diamond.
Object-Oriented Parallel Particle-in-Cell Code for Beam Dynamics Simulation in Linear Accelerators
Qiang, J.; Ryne, R.D.; Habib, S.; Decky, V.
1999-11-13
In this paper, we present an object-oriented three-dimensional parallel particle-in-cell code for beam dynamics simulation in linear accelerators. A two-dimensional parallel domain decomposition approach is employed within a message passing programming paradigm along with a dynamic load balancing. Implementing object-oriented software design provides the code with better maintainability, reusability, and extensibility compared with conventional structure based code. This also helps to encapsulate the details of communications syntax. Performance tests on SGI/Cray T3E-900 and SGI Origin 2000 machines show good scalability of the object-oriented code. Some important features of this code also include employing symplectic integration with linear maps of external focusing elements and using z as the independent variable, typical in accelerators. A successful application was done to simulate beam transport through three superconducting sections in the APT linac design.
Recent results in analysis and simulation of beam halo
Ryne, Robert D.; Wangler, Thomas P.
1995-09-15
Understanding and predicting beam halo is a major issue for accelerator driven transmutation technologies. If strict beam loss requirements are not met, the resulting radioactivation can reduce the availability of the accelerator facility and may lead to the necessity for time-consuming remote maintenance. Recently there has been much activity related to the core-halo model of halo evolution [1-5]. In this paper we will discuss the core-halo model in the context of constant focusing channels and periodic focusing channels. We will present numerical results based on this model and we will show comparisons with results from large scale particle simulations run on a massively parallel computer. We will also present results from direct Vlasov simulations.
Recent results in analysis and simulation of beam halo
Ryne, R.D.; Wangler, T.P.
1994-09-01
Understanding and predicting beam halo is a major issue for accelerator driven transmutation technologies. If strict beam loss requirements are not met, the resulting radioactivation can reduce the availability of the accelerator facility and may lead to the necessity for time-consuming remote maintenance. Recently there has been much activity related to the core-halo model of halo evolution. In this paper the authors will discuss the core-halo model in the context of constant focusing channels and periodic focusing channels. They will present numerical results based on this model and they will show comparisons with results from large scale particle simulations run on a massively parallel computer. They will also present results from direct Vlasov simulations.
NASA Astrophysics Data System (ADS)
Zhang, Xu; Li, Ming; Wei, Sumin; Xing, Jiansheng; Hu, Yueming; Johnson, Richard R.; Piazza, Leandro; Ryjkov, Vladimir
2016-06-01
From the stripping points, the high intensity proton beam of a compact cyclotron travels through the fringe field area of the machine to the combination magnet. Starting from there the beams with various energy is transferred to the switching magnet for distribution to the beam line targets. In the design of the extraction and transport system for the compact proton cyclotron facilities, such as the 70 MeV in France and the 100 MeV in China, the space charge effect as the beam crosses the fringe field has not been previously considered; neither has the impact on transverse beam envelope coupled from the longitudinal direction. Those have been concerned much more with the higher beam-power because of the beam loss problem. In this paper, based on the mapping data of 70 MeV cyclotron including the fringe field by BEST Cyclotron Inc (BEST) and combination magnet field by China Institute of Atomic Energy (CIAE), the beam extraction and transport are investigated for the 70 MeV cyclotron used on the SPES project at Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro (INFN-LNL). The study includes the space charge effect and longitudinal and transverse coupling mentioned above, as well as the matching of beam optics using the beam line for medical isotope production as an example. In addition, the designs of the ±45° switching magnets and the 60° bending magnet for the extracted beam with the energy from 35 MeV to 70 MeV have been made. Parts of the construction and field measurements of those magnets have been done as well. The current result shows that, the design considers the complexity of the compact cyclotron extraction area and fits the requirements of the extraction and transport for high intensity proton beam, especially at mA intensity levels.
Transport simulations of the ignited ITER with high helium fraction
NASA Astrophysics Data System (ADS)
Becker, G.
1994-04-01
Computer simulations with special versions of the one dimensional BALDUR predictive transport code are carried out to investigate the particle confinement of helium and hydrogen, the energy confinement and the burn control in the high density scenario of the ITER (CDA) physics phase. The code uses empirical transport coefficients for ELMy H mode plasmas, an improved model of the scrape-off layer (SOL), an impurity radiation model for helium and iron, and fast burn control by neutral beam injection feedback. A self-sustained thermonuclear burn is achieved for hundreds of seconds. The necessary radiation corrected energy confinement time τE is found to be 4.2 s, which is attainable according to the ITER H mode scaling. In the ignited ITER, a significant dilution of the DT fuel by helium takes place. Steady state helium fractions of up to 8% are obtained, which are found to be compatible with self-sustained burn. The SOL model yields self-consistent electron densities and temperatures at the separatrix (ne = 5.8 × 1019 m-3, Te = 80 eV)
Computer simulation of ion beam analysis of laterally inhomogeneous materials
NASA Astrophysics Data System (ADS)
Mayer, M.
2016-03-01
The program STRUCTNRA for the simulation of ion beam analysis charged particle spectra from arbitrary two-dimensional distributions of materials is described. The code is validated by comparison to experimental backscattering data from a silicon grating on tantalum at different orientations and incident angles. Simulated spectra for several types of rough thin layers and a chessboard-like arrangement of materials as example for a multi-phase agglomerate material are presented. Ambiguities between back-scattering spectra from two-dimensional and one-dimensional sample structures are discussed.
Simulation of radial expansion of an electron beam injected into a background plasma
NASA Technical Reports Server (NTRS)
Koga, J.; Lin, C. S.
1989-01-01
A 2-D electrostatic particle code was used to study the beam radial expansion of a nonrelativistic electron beam injected from an isolated equipotential conductor into a background plasma. The simulations indicate that the beam radius is generally proportional to the beam electron gyroradius when the conductor is charged to a large potential. The simulations also suggest that the charge buildup at the beam stagnation point causes the beam radial expansion. From a survey of the simulation results, it is found that the ratio of the beam radius to the beam electron gyroradius increases with the square root of beam density and decreases inversely with beam injection velocity. This dependence is explained in terms of the ratio of the beam electron Debye length to the ambient electron Debye length. These results are most applicable to the SEPAC electron beam injection experiments from Spacelab 1, where high charging potential was observed.
Simulations of Large-Area Electron Beam Diodes
NASA Astrophysics Data System (ADS)
Swanekamp, S. B.; Friedman, M.; Ludeking, L.; Smithe, D.; Obenschain, S. P.
1999-11-01
Large area electron beam diodes are typically used to pump the amplifiers of KrF lasers. Simulations of large-area electron beam diodes using the particle-in-cell code MAGIC3D have shown the electron flow in the diode to be unstable. Since this instability can potentially produce a non-uniform current and energy distribution in the hibachi structure and lasing medium it can be detrimental to laser efficiency. These results are similar to simulations performed using the ISIS code.(M.E. Jones and V.A. Thomas, Proceedings of the 8^th) International Conference on High-Power Particle Beams, 665 (1990). We have identified the instability as the so called ``transit-time" instability(C.K. Birdsall and W.B. Bridges, Electrodynamics of Diode Regions), (Academic Press, New York, 1966).^,(T.M. Antonsen, W.H. Miner, E. Ott, and A.T. Drobot, Phys. Fluids 27), 1257 (1984). and have investigated the role of the applied magnetic field and diode geometry. Experiments are underway to characterize the instability on the Nike KrF laser system and will be compared to simulation. Also some possible ways to mitigate the instability will be presented.
Estimation and simulation of multi-beam sonar noise.
Holmin, Arne Johannes; Korneliussen, Rolf J; Tjøstheim, Dag
2016-02-01
Methods for the estimation and modeling of noise present in multi-beam sonar data, including the magnitude, probability distribution, and spatial correlation of the noise, are developed. The methods consider individual acoustic samples and facilitate compensation of highly localized noise as well as subtraction of noise estimates averaged over time. The modeled noise is included in an existing multi-beam sonar simulation model [Holmin, Handegard, Korneliussen, and Tjøstheim, J. Acoust. Soc. Am. 132, 3720-3734 (2012)], resulting in an improved model that can be used to strengthen interpretation of data collected in situ at any signal to noise ratio. Two experiments, from the former study in which multi-beam sonar data of herring schools were simulated, are repeated with inclusion of noise. These experiments demonstrate (1) the potentially large effect of changes in fish orientation on the backscatter from a school, and (2) the estimation of behavioral characteristics such as the polarization and packing density of fish schools. The latter is achieved by comparing real data with simulated data for different polarizations and packing densities. PMID:26936566
Automated analysis for detecting beams in laser wakefield simulations
Ushizima, Daniela M.; Rubel, Oliver; Prabhat, Mr.; Weber, Gunther H.; Bethel, E. Wes; Aragon, Cecilia R.; Geddes, Cameron G.R.; Cormier-Michel, Estelle; Hamann, Bernd; Messmer, Peter; Hagen, Hans
2008-07-03
Laser wakefield particle accelerators have shown the potential to generate electric fields thousands of times higher than those of conventional accelerators. The resulting extremely short particle acceleration distance could yield a potential new compact source of energetic electrons and radiation, with wide applications from medicine to physics. Physicists investigate laser-plasma internal dynamics by running particle-in-cell simulations; however, this generates a large dataset that requires time-consuming, manual inspection by experts in order to detect key features such as beam formation. This paper describes a framework to automate the data analysis and classification of simulation data. First, we propose a new method to identify locations with high density of particles in the space-time domain, based on maximum extremum point detection on the particle distribution. We analyze high density electron regions using a lifetime diagram by organizing and pruning the maximum extrema as nodes in a minimum spanning tree. Second, we partition the multivariate data using fuzzy clustering to detect time steps in a experiment that may contain a high quality electron beam. Finally, we combine results from fuzzy clustering and bunch lifetime analysis to estimate spatially confined beams. We demonstrate our algorithms successfully on four different simulation datasets.
Scheme for Low Energy Beam Transport with a Non-Neutralized Section
Shemyakin, A.; Prost, L.
2015-04-23
A typical Low Energy Beam Transport (LEBT) design relies on dynamics with nearly complete beam space charge neutralization over the entire length of the LEBT. This paper argues that, for a beam with modest perveance and uniform current density distribution when generated at the source, a downstream portion of the LEBT can be un-neutralized without significant emittance growth.
Understanding extraction and beam transport in the ISIS H{sup -} Penning surface plasma ion source
Faircloth, D. C.; Letchford, A. P.; Gabor, C.; Whitehead, M. O.; Wood, T.; Jolly, S.; Pozimski, J.; Savage, P.; Woods, M.
2008-02-15
The ISIS H{sup -} Penning surface plasma source has been developed to produce beam currents up to 70 mA and pulse lengths up to 1.5 ms at 50 Hz. This paper details the investigation into beam extraction and beam transport in an attempt to understand the beam emittance and to try to improve the emittance. A scintillator profile measurement technique has been developed to assess the performance of different plasma electrode apertures, extraction electrode geometries, and postextraction acceleration configurations. This work shows that the present extraction, beam transport, and postacceleration system are suboptimal and further work is required to improve it.
Simulation study of proton transport in ionomers
NASA Astrophysics Data System (ADS)
Taylor, Philip; Allahyarov, Elshad
2008-03-01
Coarse-grained molecular-dynamics simulations were used to study the morphological changes induced in a Nafion-like ionomer by the imposition of a strong electric field. We observe that proton transport through this polymer electrolyte membrane is accompanied by morphological changes that include the formation of structures aligned along the direction of the applied field. The polar head groups of the ionomer side chains assemble into clusters, which then form rod-like formations, and these cylindrical structures then assemble into a hexagonally ordered array aligned with the direction of current flow. For dry ionomers, at current densities in excess of 1 A/cm^2 these rod-like clusters undergo an inner micro-phase separation, in which distinct wire-like lines of sulfonate head groups are accompanied by similar wire-like alignments of bound protons. The clusters appear to be of two types. If there are two, four, or five lines of sulfonates then there is an equal number of lines of protons, but if there are three lines of sulfonates then they are accompanied by four lines of protons. Occasionally these lines of sulfonates and protons form a helical structure. Upon removal of the electric field, the hexagonal array of rod-like structures remains, but the microphase separation disappears below the threshold current of 1 A/cm^2.
Carlsten, B.E.
1997-02-01
The author analyzes the emittance growth mechanisms for a continuous, intense electron beam in a focusing transport channel, over distances short enough that the beam does not reach equilibrium. The emittance grows from the effect of nonlinear forces arising from (1) current density nonuniformities, (2) energy variations leading to nonlinearities in the space-charge force even if the current density is uniform, (3) axial variations in the radial vector potential, (4) an axial velocity shear along the beam, and (5) an energy redistribution of the beam as the beam compresses or expands. The emittance growth is studied analytically and numerically for the cases of balanced flow, tight focusing, and slight beam scalloping, and is additionally studied numerically for an existing 6-MeV induction linear accelerator. Rules for minimizing the emittance along a beamline are established. Some emittance growth will always occur, both from current density nonuniformities that arise along the transport and from beam radius changes along the transport.
NASA Astrophysics Data System (ADS)
Bauer, J.; Sommerer, F.; Mairani, A.; Unholtz, D.; Farook, R.; Handrack, J.; Frey, K.; Marcelos, T.; Tessonnier, T.; Ecker, S.; Ackermann, B.; Ellerbrock, M.; Debus, J.; Parodi, K.
2014-08-01
Monte Carlo (MC) simulations of beam interaction and transport in matter are increasingly considered as essential tools to support several aspects of radiation therapy. Despite the vast application of MC to photon therapy and scattered proton therapy, clinical experience in scanned ion beam therapy is still scarce. This is especially the case for ions heavier than protons, which pose additional issues like nuclear fragmentation and varying biological effectiveness. In this work, we present the evaluation of a dedicated framework which has been developed at the Heidelberg Ion Beam Therapy Center to provide automated FLUKA MC simulations of clinical patient treatments with scanned proton and carbon ion beams. Investigations on the number of transported primaries and the dimension of the geometry and scoring grids have been performed for a representative class of patient cases in order to provide recommendations on the simulation settings, showing that recommendations derived from the experience in proton therapy cannot be directly translated to the case of carbon ion beams. The MC results with the optimized settings have been compared to the calculations of the analytical treatment planning system (TPS), showing that regardless of the consistency of the two systems (in terms of beam model in water and range calculation in different materials) relevant differences can be found in dosimetric quantities and range, especially in the case of heterogeneous and deep seated treatment sites depending on the ion beam species and energies, homogeneity of the traversed tissue and size of the treated volume. The analysis of typical TPS speed-up approximations highlighted effects which deserve accurate treatment, in contrast to adequate beam model simplifications for scanned ion beam therapy. In terms of biological dose calculations, the investigation of the mixed field components in realistic anatomical situations confirmed the findings of previous groups so far reported only in
Fast Ignition Transport Simulations for NIF
Strozzi, D J; Grote, D P; Tabak, M; Cohen, B I; Town, R P; Kemp, A J
2009-10-05
This paper shows work at Lawrence Livermore National Lab (LLNL) devoted to modeling the propagation of, and heating by, a relativistic electron beam in a idealized dense fuel assembly for fast ignition. The implicit particle-in-cell (PIC) code LSP is used. Experiments planned on the National Ignition Facility (NIF) in the next few years using the Advanced Radiography Capability (ARC) short-pulse laser motivate this work. We demonstrate significant improvement in the heating of dense fuel due to magnetic forces, increased beam collimation, and insertion of a finite-radius carbon region between the beam excitation and fuel regions.
Simulations and Observations of Heating of Auroral Ion Beams
NASA Technical Reports Server (NTRS)
Winglee, R. M.; Dusenbery, P. B.; Collin, H. L.; Lin, C. S.; Persoon, A. M.
1989-01-01
In the auroral zone, quasi-static parallel electric fields produce beams of ionospheric ions (e.g., H(+), He(+) and 0(+)), which flow outward into the magnetosphere, providing a significant source of ions for the ring current and plasma sheet. Because the velocities to which these beams are accelerated is dependent on the mass of the ions, differential flows between the various ion species can develop which are unstable to an ion-ion streaming instability. Particle simulations and observations from DE 1 are used to investigate the heating of the ion beams produced by this instability. It is shown that there is net transfer of energy from the light ions to the heavy ions, with the heavy ions reaching maximum velocities near the beam velocity of the light ions. Bulk heating of the heavy ions occurs when their relative density is low while high-energy tails are produced when their relative density is high. The heating is primarily parallel to the magnetic field if the difference in the heavy and light ion beam velocities is subsonic while both perpendicular and parallel heating can occur if it is supersonic. In the latter case, very strong heating of an intermediate ion's species such as He(+) can also occur. Comparison with observations shows features consistent with heating via the ion-ion instability including perpendicular heating in the supersonic regime and parallel heating in the subsonic regime and a change in the heating between these regimes as the ratio of the H(+) beam speed to the local sound speed is observed to decrease. This heating is, however, not always observed in association with enhanced wave emissions. This lack of waves is attributed to reabsorption of the waves as the ions become heated.
NASA Astrophysics Data System (ADS)
Hwu, Justin Jia-Jen
2000-10-01
The electron beam induced conductivity (EBIC) effect of polymer materials was investigated and three electron beam resists, PBS, EBR900, and ZEP7000, were used as target materials in this research. An external bias method was applied for the direct measurements of EBIC current and the EBIC conductivity was then derived. The temperature effect on EBIC was illustrated by EBR900 and a simple single trap level analysis gave good agreement in explanation of initial state conductivity dependence on temperature change. The dependence of initial state EBIC values on dose rates and bias was also determined and an empirical from of EBIC-bias relationship was established for the electron beam deflection modeling. The long term EBIC characteristics of resists were investigated under different dose rates. The variation of EBIC versus time was explained by a transient theory that considers rates of carrier generation, carrier trapping, carrier detrapping, and carrier recombination contribution. The trapping model analysis on steady state EBIC results revealed that PBS has a uniform distribution of traps, while EBR900 and ZEP7000 fall in the same category that has exponential distribution of traps. The steady state EBIC gain was also determined for the three resists and the onset of the plasma region was observed for EBR900 and ZEP7000. A simulation model for the calculation of electron beam deflection owing to resist charging was developed in the second part of this research. Charging patterns of circles and squares of different dimensions were considered. Both SIMION and MATHEMATICA were used as simulation tools and the limitation of SIMION was illustrated and discussed. The model programmed in MATHEMATICA simulated electron beam deflection during e-beam writing. With the combination of the empirical EBIC-bias relationship of EBR900, the model simulated surface potential decay after irradiation and the results showed good agreement with literature values. The extent of
BEAM TRANSPORT AND STORAGE WITH COLD NEUTRAL ATOMS AND MOLECULES
Walstrom, Peter L.
2012-05-15
A large class of cold neutral atoms and molecules is subject to magnetic field-gradient forces. In the presence of a field, hyperfine atomic states are split into several Zeeman levels. The slopes of these curves vs. field are the effective magnetic moments. By means of optical pumping in a field, Zeeman states of neutral lithium atoms and CaH molecules with effective magnetic moments of nearly {+-} one Bohr magneton can be selected. Particles in Zeeman states for which the energy increases with field are repelled by increasing fields; particles in states for which the energy decreases with field are attracted to increasing fields. For stable magnetic confinement, field-repelled states are required. Neutral-particle velocities in the present study are on the order of tens to hundreds of m/s and the magnetic fields needed for transport and injection are on the order of in the range of 0.01-1T. Many of the general concepts of charged-particle beam transport carry over into neutral particle spin-force optics, but with important differences. In general, the role of bending dipoles in charged particle optics is played by quadrupoles in neutral particle optics; the role of quadrupoles is played by sextupoles. The neutralparticle analog of charge-exchange injection into storage rings is the use of lasers to flip the state of particles from field-seeking to field-repelled. Preliminary tracking results for two neutral atom/molecule storage ring configurations are presented. It was found that orbit instabilities limit the confinment time in a racetrack-shaped ring with discrete magnetic elements with drift spaces between them; stable behavior was observed in a toroidal ring with a continuous sextupole field. An alternative concept using a linear sextupole or octupole channel with solenoids on the ends is presently being considered.
Beam control and diagnostic functions in the NIF transport spatial filter
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.
Design of a high-current low-energy beam transport line for an intense D-T/D-D neutron generator
NASA Astrophysics Data System (ADS)
Lu, Xiaolong; Wang, Junrun; Zhang, Yu; Li, Jianyi; Xia, Li; Zhang, Jie; Ding, Yanyan; Jiang, Bing; Huang, Zhiwu; Ma, Zhanwen; Wei, Zheng; Qian, Xiangping; Xu, Dapeng; Lan, Changlin; Yao, Zeen
2016-03-01
An intense D-T/D-D neutron generator is currently being developed at the Lanzhou University. The Cockcroft-Walton accelerator, as a part of the neutron generator, will be used to accelerate and transport the high-current low-energy beam from the duoplasmatron ion source to the rotating target. The design of a high-current low-energy beam transport (LEBT) line and the dynamics simulations of the mixed beam were carried out using the TRACK code. The results illustrate that the designed beam line facilitates smooth transportation of a deuteron beam of 40 mA, and the number of undesired ions can be reduced effectively using two apertures.
Simulations of Parametric Resonance Ionization Cooling of Muon Beams
K. Beard; S.A. Bogacz; Y.S. Derbenev; R.P. Johnson; K. Paul; T.J. Roberts; K. Yonehara
2005-05-16
The technique of using a parametric resonance to allow better ionization cooling is being developed to create small beams so that high collider luminosity can be achieved with fewer muons. In the linear channel that is studied in this effort, a half integer resonance is induced such that the normal elliptical motion of particles in x-x' phase space becomes hyperbolic, with particles moving to smaller x and larger x' as they pass down the channel. Thin absorbers placed at the focal points of the channel then cool the angular divergence of the beam by the usual ionization cooling mechanism where each absorber is followed by RF cavities. Thus the phase space of the beam is compressed in transverse position by the dynamics of the resonance and its angular divergence is compressed by the ionization cooling mechanism. We report the first results of simulations of this process, including comparisons to theoretical cooling rates and studies of sensitivity to variations in absorber thickness and initial beam conditions.
Simulation of Electron-Beam Irradiation of Skin Tissue Model
Miller, John H.; Suleiman, Atef; Chrisler, William B.; Sowa, Marianne B.
2011-01-03
Monte Carlo simulation of electrons stopping in liquid water was used to model the penetration and dose distribution of electron beams incident on the full-thickness EpiDermTM skin model (MatTek, Ashland, VA). This 3D tissue model has a fully developed basement membrane separating an epidermal layer of keratinocytes in various stages of differentiation from a dermal layer of fibroblast embedded in collagen. The simulations were motivated by a desire to selectively expose the epidermal layer to low linear-energy-transfer (LET) radiation in the presence of a non-irradiated dermal layer. Using the variable energy electron microbeam at the Pacific Northwest National Laboratory (PNNL) as a model of device characteristics and irradiation geometry, we find that at the highest beam energy available (90 keV), the estimated 90th percentile of penetration remains in the epidermal layer. To investigate the depth-dose distribution, we calculated lineal energy spectra for 10um thick layers near the 10th, 50th, and 90th percentile of penetration by the 90 keV electron beam. Biphasic spectra showed an increasing component of "stoppers" with increasing depth. Despite changes in the lineal energy spectra, the main effect on dose deposition with increasing depth is the screening effect of tissue above the layer of interest.
Many-beam dynamical simulation of electron backscatter diffraction patterns.
Winkelmann, Aimo; Trager-Cowan, Carol; Sweeney, Francis; Day, Austin P; Parbrook, Peter
2007-01-01
We present an approach for the simulation of complete electron backscatter diffraction (EBSD) patterns where the relative intensity distributions in the patterns are accurately reproduced. The Bloch wave theory is applied to describe the electron diffraction process. For the simulation of experimental patterns with a large field of view, a large number of reflecting planes has to be taken into account. This is made possible by the Bethe perturbation of weak reflections. Very good agreement is obtained for simulated and experimental patterns of gallium nitride GaN{0001} at 20kV electron energy. Experimental features like zone-axis fine structure and higher-order Laue zone rings are accurately reproduced. We discuss the influence of the diffraction of the incident beam in our experiment. PMID:17126489
Simulation of spatial fuel assay using HANARO neutron beam
Lee; Chang; Lee; Kim
2000-10-01
A sensitivity simulation of neutron tomography was performed for the analysis of the spatial distribution of nuclear materials in the HANARO fuel rod. The internal distribution of the nuclear materials in the fuel rod is very important for the increase of the safety and economics of fuel burnup in the reactor. The neutron radiography facility installed at HANARO will be used for the spatial fuel analysis with a real-time image processing system. Monte Carlo simulation was performed to study the feasibility and sensitivity of the HANARO neutron beam for the spatial fuel assay and to find the optimum conditions for neutron detection. From the sensitivity simulation, the location of the nuclear materials in the rod was evident as expected. PMID:11003495
Efficient Monte Carlo simulations in kilovoltage x-ray beams
NASA Astrophysics Data System (ADS)
Mainegra-Hing, Ernesto
Kilovoltage x-ray systems are modeled with BEAMnrc using directional bremsstrahlung splitting, which is five to six orders of magnitude more efficient than a simulation without splitting and 60 times more efficient than uniform bremsstrahlung splitting. Optimum splitting numbers are between 2 and 3 orders of magnitude larger than for megavoltage beams A self-consistent approach for the calculation of free-air chamber correction factors with the EGSnrc Monte Carlo system is introduced. In addition to the traditional factors employed to correct for attenuation (A att), photon scatter (Ascat) and electron energy loss (Aeloss), correction factors for aperture leakage (Aap) and backscatter (A b) are defined. Excellent agreement is obtained between calculated and measured Ascat and Aeloss values. Computed Aatt values for medium-energy and mammography beams reproduce the measurements well. For low-energy lightly-filtered beams, Aatt values show significant differences with the experiment. Scaling the tungsten L-shell EII cross-sections by a factor of 2 eliminate these differences. The inconsistency of the evacuated-tube technique for measuring Aatt is negligible for medium-energy and mammography beams, and 0.2% for low-energy lightly-filtered beams The aperture correction Aap becomes significant in the medium-energy range with increasing energy. The newly introduced backscatter correction Ab becomes as high as 0.4% in the low-energy range. In the medium-energy range, calculations reproduce experimental half-value layer values to better than 2.3%. For mammography beams a difference of 0.5% and 2.5% with experiment is obtained with and without a scaling of the tungsten L-shell EII cross-sections respectively. For low-energy lightly-filtered beams a scaling factor of 2.1 gives the best agreement (˜ 3%) with the experiment, significantly worsening to 8% for a scaling factor of 1.8, which gives the best match for Aatt. The fast algorithm for calculating the scatter
Energy Transport Effects in Flaring Atmospheres Heated by Mixed Particle Beams
NASA Astrophysics Data System (ADS)
Zharkova, Valentina; Zharkov, Sergei; Macrae, Connor; Druett, Malcolm; Scullion, Eamon
2016-07-01
We investigate energy and particle transport in the whole flaring atmosphere from the corona to the photosphere and interior for the flaring events on the 1st July 2012, 6 and 7 September 2011 by using the RHESSI and SDO instruments as well as high-resolution observations from the Swedish 1-metre Solar Telescope (SST3) CRISP4 (CRisp Imaging Spectro-polarimeter). The observations include hard and soft X-ray emission, chromospheric emission in both H-alpha 656.3 nm core and continuum, as well as, in the near infra-red triplet Ca II 854.2 nm core and continuum channels and local helioseismic responses (sunquakes). The observations are compared with the simulations of hard X-ray emission and tested by hydrodynamic simulations of flaring atmospheres of the Sun heated by mixed particle beams. The temperature, density and macro-velocity variations of the ambient atmospheres are calculated for heating by mixed beams and the seismic response of the solar interior to generation of supersonic shocks moving into the solar interior. We investigate the termination depths of these shocks beneath the quiet photosphere levels and compare them with the parameters of seismic responses in the interior, or sunquakes (Zharkova and Zharkov, 2015). We also present an investigation of radiative conditions modelled in a full non-LTE approach for hydrogen during flare onsets with particular focus on Balmer and Paschen emission in the visible, near UV and near IR ranges and compare them with observations. The links between different observational features derived from HXR, optical and seismic emission are interpreted by different particle transport models that will allow independent evaluation of the particle transport scenarios.
Zhou, Y. L.; Wang, Z. H.; Xu, X. Q.; Li, H. D.; Feng, H.; Sun, W. G.
2015-01-15
Plasma fueling with high efficiency and deep injection is very important to enable fusion power performance requirements. It is a powerful and efficient way to study neutral transport dynamics and find methods of improving the fueling performance by doing large scale simulations. Two basic fueling methods, gas puffing (GP) and supersonic molecular beam injection (SMBI), are simulated and compared in realistic divertor geometry of the HL-2A tokamak with a newly developed module, named trans-neut, within the framework of BOUT++ boundary plasma turbulence code [Z. H. Wang et al., Nucl. Fusion 54, 043019 (2014)]. The physical model includes plasma density, heat and momentum transport equations along with neutral density, and momentum transport equations. Transport dynamics and profile evolutions of both plasma and neutrals are simulated and compared between GP and SMBI in both poloidal and radial directions, which are quite different from one and the other. It finds that the neutrals can penetrate about four centimeters inside the last closed (magnetic) flux surface during SMBI, while they are all deposited outside of the LCF during GP. It is the radial convection and larger inflowing flux which lead to the deeper penetration depth of SMBI and higher fueling efficiency compared to GP.
Zhou, Y. L.; Wang, Z. H.; Xu, X. Q.; Li, H. D.; Feng, H.; Sun, W. G.
2015-01-09
Plasma fueling with high efficiency and deep injection is very important to enable fusion power performance requirements. It is a powerful and efficient way to study neutral transport dynamics and find methods of improving the fueling performance by doing large scale simulations. Furthermore, two basic fueling methods, gas puffing (GP) and supersonic molecular beam injection (SMBI), are simulated and compared in realistic divertor geometry of the HL-2A tokamak with a newly developed module, named trans-neut, within the framework of BOUT++ boundary plasma turbulence code [Z. H. Wang et al., Nucl. Fusion 54, 043019 (2014)]. The physical model includes plasma density,more » heat and momentum transport equations along with neutral density, and momentum transport equations. In transport dynamics and profile evolutions of both plasma and neutrals are simulated and compared between GP and SMBI in both poloidal and radial directions, which are quite different from one and the other. It finds that the neutrals can penetrate about four centimeters inside the last closed (magnetic) flux surface during SMBI, while they are all deposited outside of the LCF during GP. Moreover, it is the radial convection and larger inflowing flux which lead to the deeper penetration depth of SMBI and higher fueling efficiency compared to GP.« less
White Paper on Ion Beam Transport for ICF: Issues, R&D Need,and Tri-Lab Plans
Olson, C.; Lee, E.; Langdon, B.
2005-05-04
To date, most resources for ion beam fusion have been devoted to development of accelerators and target physics; relatively few resources have gone into ion beam transport development. Because of theoretical studies and substantial experience with electron beam transport, the ion beam transport community is now poised to develop and optimize ion beam transport for ICF. Because of this Tri-Lab effort, a path for coordinated development of ion beam transport has been established. The rate of progress along this path will now be determined largely by the availability of resources.
Simulation study of interactions of Space Shuttle-generated electron beams with ambient plasmas
NASA Technical Reports Server (NTRS)
Lin, Chin S.
1992-01-01
This report summarizes results obtained through the support of NASA Grant NAGW-1936. The objective of this report is to conduct large scale simulations of electron beams injected into space. The topics covered include the following: (1) simulation of radial expansion of an injected electron beam; (2) simulations of the active injections of electron beams; (3) parameter study of electron beam injection into an ionospheric plasma; and (4) magnetosheath-ionospheric plasma interactions in the cusp.
The Mechanical Design for the DARHT-II Downstream Beam Transport Line
NASA Astrophysics Data System (ADS)
Westenskow, Glen
This paper describes the mechanical design of the downstream beam transport line for the second axis of the Dual Axis Radiographic Hydrodynamic Test (DARHT II) Facility. The DARHT-II project is a collaboration between LANL, LBNL and LLNL. DARHT II is a 20-MeV, 2000-Amperes, 2-msec linear induction accelerator designed to generate short bursts of x-rays for the purpose of radiographing dense objects. The down-stream beam transport line is approximately 20-meter long region extending from the end of the accelerator to the bremsstrahlung target. Within this proposed transport line there are 15 conventional solenoid, quadrupole and dipole magnets; as well as several speciality magnets, which transport and focus the beam to the target and to the beam dumps. There are two high power beam dumps, which are designed to absorb 80-kJ per pulse during accelerator start-up and operation. Aspects of the mechanical design of these elements are presented.
EBQ code: transport of space-charge beams in axially symmetric devices
Paul, A.C.
1982-11-01
Such general-purpose space charge codes as EGUN, BATES, WOLF, and TRANSPORT do not gracefully accommodate the simulation of relativistic space-charged beams propagating a long distance in axially symmetric devices where a high degree of cancellation has occurred between the self-magnetic and self-electric forces of the beam. The EBQ code was written specifically to follow high current beam particles where space charge is important in long distance flight in axially symmetric machines possessing external electric and magnetic field. EBQ simultaneously tracks all trajectories so as to allow procedures for charge deposition based on inter-ray separations. The orbits are treated in Cartesian geometry (position and momentum) with z as the independent variable. Poisson's equation is solved in cylindrical geometry on an orthogonal rectangular mesh. EBQ can also handle problems involving multiple ion species where the space charge from each must be included. Such problems arise in the design of ion sources where different charge and mass states are present.
NASA Astrophysics Data System (ADS)
Iida, Naoko; Kikuchi, Mitsuo; Mimashi, Toshihiro; Nakayama, Hisayoshi; Sakamoto, Yutaka; Satoh, Kotaro; Takasaki, Seiji; Tawada, Masafumi
2013-03-01
The KEKB collider achieved a maximum peak luminosity of 2.1×1034 cm-2 s-1 and an integrated luminosity of 1 ab-1 in its ten-year operation. Behind these glorious records there have been uncountable improvements in every subsystem. This paper describes the improvements in the beam transport line, injection kickers, septum magnets, the beam-abort system, and a newly developed pulsed-quadrupole system in detail.
Design study of the Low Energy Beam Transport system at RISP
NASA Astrophysics Data System (ADS)
Bahng, Jungbae; Kim, Eunsan; Kim, Yonghwan; Hong, In-Seok
2013-03-01
We present the design status of LEBT for the RISP that consists of two 90 degree dipoles, a multi-harmonic buncher, pair solenoids, electrostatic quadrupoles and a high voltage platform. After ECR-IS with an energy of 10 keV/u, heavy-ion beams are selected by achromatic bending systems and then be bunched in the LEBT. A multi-harmonic buncher is used to achieve a small longitudinal emittance in the RFQ. We show the results on the optics design by using the TRANSPORT code and the beam tracking of two-charge beams by using the code IMPACT. We present the results and issues on beam dynamics simulaitons in the designed LEBT system. For heavy ion beams in the low energy system, we have to separate and select desire beam. we also transport beam from ECR to RFQ with high transmission.
Beam Dynamics Studies in the RACE Project: MH1 transport line --low power regime operation-
NASA Astrophysics Data System (ADS)
Maidana, Carlos; Hunt, Alan; Beller, Denis
2007-05-01
As part of the Reactor Accelerator Coupling Experiments (RACE) a set of preliminary studies were conducted to design a transport beam line that could bring a 25MeV electron beam from a linear accelerator to a neutron-producing target inside a subcritical nuclear system. Because of the relatively low energy beam, the beam size and a relatively long beam line (implicating a possible divergence problem) the MH1 transport line was designed. Beam dynamics studies followed the beam optics ones and we present in this paper the first results of such studies. To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.NWS07.C1.8
SEAWAT-based simulation of axisymmetric heat transport.
Vandenbohede, Alexander; Louwyck, Andy; Vlamynck, Nele
2014-01-01
Simulation of heat transport has its applications in geothermal exploitation of aquifers and the analysis of temperature dependent chemical reactions. Under homogeneous conditions and in the absence of a regional hydraulic gradient, groundwater flow and heat transport from or to a well exhibit radial symmetry, and governing equations are reduced by one dimension (1D) which increases computational efficiency importantly. Solute transport codes can simulate heat transport and input parameters may be modified such that the Cartesian geometry can handle radial flow. In this article, SEAWAT is evaluated as simulator for heat transport under radial flow conditions. The 1971, 1D analytical solution of Gelhar and Collins is used to compare axisymmetric transport with retardation (i.e., as a result of thermal equilibrium between fluid and solid) and a large diffusion (conduction). It is shown that an axisymmetric simulation compares well with a fully three dimensional (3D) simulation of an aquifer thermal energy storage systems. The influence of grid discretization, solver parameters, and advection solution is illustrated. Because of the high diffusion to simulate conduction, convergence criterion for heat transport must be set much smaller (10(-10) ) than for solute transport (10(-6) ). Grid discretization should be considered carefully, in particular the subdivision of the screen interval. On the other hand, different methods to calculate the pumping or injection rate distribution over different nodes of a multilayer well lead to small differences only. PMID:24571415
Simulation of large motions of nonuniform beams in orbit. I - The cantilever beam
NASA Technical Reports Server (NTRS)
Levinson, D. A.; Kane, T. R.
1981-01-01
An algorithm is developed for producing numerical simulations of large motions of a nonuniform cantilever beam in orbit. Special emphasis is given to the effective formulation of equations of motion and to the use of the finite element method to construct modal functions. Finite element methods are used to generate modal functions in such a way as to permit a particularly harmonious relationship to be established between the disciplines of rigid body dynamics and structural analysis. Sufficient information is provided to enable a reader to create, with relatively little effort, his own simulation program; simulation results are reported, both to provide check cases for other investigators and to illustrate certain important facets of the behavior of flexible spacecraft.
Simulation of phase noise for coherent beam combination
NASA Astrophysics Data System (ADS)
Hu, Qi-qi; Huang, Zhi-meng; Tang, Xuan; Luo, Yong-quan; Zhang, Da-yong
2015-02-01
Active coherent beam combination has been a hot area of research for several years. Particular algorithm module is used to stabilize the phase difference between beamlets, and make them coherent. The phase noise increases with the raising power of laser output. Under low power condition, we simulate the phase noise of high power laser amplifier by the Arbitrary Function Generators (AFGs), and send them to the phase modulators to destabilize the phase, to test the performance of the phase lock algorithm. The experimental results show the feasibility.
A simulation study of radial expansion of an electron beam injected into an ionospheric plasma
NASA Technical Reports Server (NTRS)
Koga, J.; Lin, C. S.
1994-01-01
Injections of nonrelativistic electron beams from a finite equipotential conductor into an ionospheric plasma have been simulated using a two-dimensional electrostatic particle code. The purpose of the study is to survey the simulation parameters for understanding the dependence of beam radius on physical variables. The conductor is charged to a high potential when the background plasma density is less than the beam density. Beam electrons attracted by the charged conductor are decelerated to zero velocity near the stagnation point, which is at a few Debye lengths from the conductor. The simulations suggest that the beam electrons at the stagnation point receive a large transverse kick and the beam expands radially thereafter. The buildup of beam electrons at the stagnation point produces a large electrostatic force responsible for the transverse kick. However, for the weak charging cases where the background plasma density is larger than the beam density, the radial expansion mechanism is different; the beam plasma instability is found to be responsible for the radial expansion. The simulations show that the electron beam radius for high spacecraft charging cases is of the order of the beam gyroradius, defined as the beam velocity divided by the gyrofrequency. In the weak charging cases, the beam radius is only a fraction of the beam gyroradius. The parameter survey indicates that the beam radius increases with beam density and decreases with magnetic field and beam velocity. The beam radius normalized by the beam gyroradius is found to scale according to the ratio of the beam electron Debye length to the ambient electron Debye length. The parameter dependence deduced would be useful for interpreting the beam radius and beam density of electron beam injection experiments conducted from rockets and the space shuttle.
Thomae, R.; Gough, R.; Keller, R.; Leung, K.N.; Schenkel, T.; Aleksandrov, A.; Stockli, M.; Welton, R.
2001-09-01
The ion source and Low Energy Beam Transport section of the front-end systems presently being built by Berkeley Lab are required to provide 50 mA of H - beam current at 6% duty factor (1 ms pulses at 60 Hz) with a normalized rms emittance of less than 0.20 p-mm-mrad. Experimental results, including emittance, chopping, and steering measurements, on the performance of the ion source and LEBT system operated at the demanded beam parameters will be discussed.
Lattice Boltzmann Simulations of Peristaltic Particle Transport
NASA Astrophysics Data System (ADS)
Connington, Kevin; Kang, Qinjun; Viswanathan, Hari; Chen, Shiyi; Abdel-Fattah, Amr
2008-11-01
A peristaltic flow occurs when a tube or channel with flexible walls transports the contained fluid by progressing a series of contraction or expansion waves along the length of those walls. It is a mechanism used to transport fluid and immersed solid particles when it is ineffective or impossible to impose a favorable pressure gradient or desirous to avoid contact between the transported mixture and mechanical moving parts. Peristaltic transport occurs in many physiological situations and has myriad industrial applications. We focus our study on the peristaltic transport of a macroscopic particle in a two dimensional channel using the Lattice Boltzmann Method (LBM). We systematically investigate the effect of variation of the relevant non-dimensional parameters of the system on the particle transport. We examine the particle behavior when the system exhibits the peculiar phenomenon of fluid ``trapping.'' Finally, we analyze how the particle presence affects stress, pressure, and dissipation in the fluid in hopes of determining preferred working conditions for peristaltic transport of shear-sensitive particles.
NASA Astrophysics Data System (ADS)
Lopez Ortega, Alejandro; Mikellides, Ioannis G.
2016-04-01
Numerical simulations with a 2-D axisymmetric multi-fluid plasma code illustrate the significance of the near-plume interactions in investigations of the anomalous electron transport in Hall thrusters. In our simulations, the transport of electrons is modeled using an anomalous collision frequency, νanom, yielding νanom ≈ ωce (i.e., the electron cyclotron frequency) in the near-plume region. We first show that restricting the anomalous collision frequency in this region to only within the ion beam, where the current density of ions is large, does not alter the plasma discharge in the Hall thruster as long as the interaction between the beam and the cathode plume is captured properly. These simulations suggest that electron transport occurs largely inside the beam. A second finding is on the significance of accounting for the ion acoustic turbulence (IAT), now known to occur in the vicinity of the cathode exit. We have included in our simulations a model of the IAT-driven anomalous collision frequency based on Sagdeev's model for saturation of the ion-acoustic instability. This implementation has allowed us to achieve excellent agreement with experimental measurements in the near plume of the H6 Hall thruster. Low frequency plasma oscillations similar in both magnitude and frequency to those found in the H6 thruster are recovered in our simulations when the model for the anomalous collision frequency in the cathode plume is included.
Perturbative Particle Simulation for an Intense Ion Beam in a Periodic Quadrupole Focusing Field
NASA Astrophysics Data System (ADS)
Lee, W. W.
1996-11-01
footnotetext[1]This work is supported the DOE contract DE-AC02-76-CHO-3073. footnotetext[2]In collaboration with Q. Qian and R. C. Davidson, PPPL. Stability and transport properties of an intense ion beam propagating through an alternating-gradient quadrupole focusing field with initial Kapchinskij-Vladimirskij (KV) distribution(I. M. Kapchinksij and V. V. Vladimirskj, Proceedings of the International Conference on High Energy Accelerators and Instrumentation (CERN Geneva, 1959), p. 274.) are studied using newly-developed perturbative particle simulation techniques. Specifically, two different schemes have been investigated: the first is based on the δ f scheme originally developed for tokamak plasmas,(A. Dimits and W. W. Lee, J. Comput. Phys. 107), 309 (1993); S. Parker and W. W. Lee, Phys. Fluids B 5, 77 (1993). and the other is related to the linearized trajectory scheme.(J. Byers, Proceedings of the 4th Conference on Numerical Simulation of Plasmas, (NRL, Washington D.C., 1970),p.496.) While the former is useful for both linear and nonlinear simulations, the latter can be used for benchmark purpose. Stability properties and associated mode structures are investigated over a wide range of beam current and focusing field strength. The new schemes are found to be highly effective in describing detailed properties of beam stability and propagation over long distances. For example, a stable KV beam can indeed propagate over hundreds of lattice period in the simulation with negligible growth. On the other hand, in the unstable region when the beam current is sufficiently high,(I. Hoffman, L. Laslett, L. Smith, and I. Haber, Particle Accelerators 13), 145 (1983). large-amplitude density perturbations with (δ n)_max/hatn0 ~ 1 with low azimuthal harmonic numbers, concentrated near the beam surface, are observed. The corresponding mode structures are of Gaussian shape in the radial direction. The physics of nonlinear saturation and emittance growth will be discussed
Simulations of electron transport and ignition for direct-drive fast-ignition targets
NASA Astrophysics Data System (ADS)
Solodov, A. A.; Anderson, K. S.; Betti, R.; Gotcheva, V.; Myatt, J.; Delettrez, J. A.; Skupsky, S.; Theobald, W.; Stoeckl, C.
2008-11-01
The performance of high-gain, fast-ignition fusion targets is investigated using one-dimensional hydrodynamic simulations of implosion and two-dimensional (2D) hybrid fluid-particle simulations of hot-electron transport, ignition, and burn. The 2D/3D hybrid-particle-in-cell code LSP [D. R. Welch et al., Nucl. Instrum. Methods Phys. Res. A 464, 134 (2001)] and the 2D fluid code DRACO [P. B. Radha et al., Phys. Plasmas 12, 056307 (2005)] are integrated to simulate the hot-electron transport and heating for direct-drive fast-ignition targets. LSP simulates the transport of hot electrons from the place where they are generated to the dense fuel core where their energy is absorbed. DRACO includes the physics required to simulate compression, ignition, and burn of fast-ignition targets. The self-generated resistive magnetic field is found to collimate the hot-electron beam, increase the coupling efficiency of hot electrons with the target, and reduce the minimum energy required for ignition. Resistive filamentation of the hot-electron beam is also observed. The minimum energy required for ignition is found for hot electrons with realistic angular spread and Maxwellian energy-distribution function.
NASA Astrophysics Data System (ADS)
Gillingham, David R.
2007-12-01
The ability to preserve the quality of relativistic electron beams through transport bend elements such as a bunch compressor chicane is increasingly difficult as the current increases because of effects such as coherent synchrotron radiation (CSR) and space-charge. Theoretical CSR models and simulations, in their current state, often make unrealistic assumptions about the beam dynamics and/or structures. Therefore, we have developed a model and simulation that contains as many of these elements as possible for the purpose of making high-fidelity end-to-end simulations. Specifically, we are able to model, in a completely self-consistent, three-dimensional manner, the sustained interaction of radiation and space-charge from a relativistic electron beam in a toroidal waveguide with rectangular cross-section. We have accomplished this by combining a time-domain field solver that integrates a paraxial wave equation valid in a waveguide when the dimensions are small compared to the bending radius with a particle-in-cell dynamics code. The result is shown to agree with theory under a set of constraints, namely thin rigid beams, showing the stimulation resonant modes and including comparisons for waveguides approximating vacuum, and parallel plate shielding. Using a rigid beam, we also develop a scaling for the effect of beam width, comparing both our simulation and numerical integration of the retarded potentials. We further demonstrate the simulation calculates the correct longitudinal space-charge forces to produce the appropriate potential depression for a converging beam in a straight waveguide with constant dimensions. We then run fully three-dimensional, self-consistent end-to-end simulations of two types of bunch compressor designs, illustrating some of the basic scaling properties and perform a detailed analysis of the output phase-space distribution. Lastly, we show the unique ability of our simulation to model the evolution of charge/energy perturbations on a
Numerical simulations of tokamak plasma turbulence and internal transport barriers
NASA Astrophysics Data System (ADS)
Thyagaraja, A.
2000-12-01
A wide variety of magnetically confined plasmas, including many tokamaks such as the JET, TFTR, JT-60U, DIII-D, RTP, show clear evidence for the existence of the so-called `internal transport barriers' (ITBs) which are regions of relatively good confinement, associated with substantial gradients in temperature and/or density. A computational approach to investigating the properties of tokamak plasma turbulence and transport is developed. This approach is based on the evolution of global, two-fluid, nonlinear, electromagnetic plasma equations of motion with specified sources. In this paper, the computational model is applied to the problem of determining the nature and physical characteristics of barrier phenomena, with particular reference to RTP (electron-cyclotron resonance heated) and JET (neutral beam heated) observations of ITBs. The simulations capture features associated with the formation of these ITBs, and qualitatively reproduce some of the observations made on RTP and JET. The picture of plasma turbulence suggested involves variations of temperature and density profiles induced by the electromagnetic fluctuations, on length scales intermediate between the system size and the ion Larmor radius, and time scales intermediate between the confinement time and the Alfvén time (collectively termed `mesoscales'). The back-reaction of such profile `corrugations' (features exhibiting relatively high local spatial gradients and rapid time variations) on the development and saturation of the turbulence itself plays a key role in the nonlinear dynamics of the system. The corrugations are found to modify the dynamical evolution of radial electric field shear and the bootstrap current density, which in turn influence the turbulence. The interaction is mediated by relatively long wavelength, electromagnetic modes excited by an inverse cascade and involving nonlinear instabilities and relaxation phenomena such as intermittency and internal mode locking.
Advanced SAR simulator with multi-beam interferometric capabilities
NASA Astrophysics Data System (ADS)
Reppucci, Antonio; Márquez, José; Cazcarra, Victor; Ruffini, Giulio
2014-10-01
State of the art simulations are of great interest when designing a new instrument, studying the imaging mechanisms due to a given scenario or for inversion algorithm design as they allow to analyze and understand the effects of different instrument configurations and targets compositions. In the framework of the studies about a new instruments devoted to the estimation of the ocean surface movements using Synthetic Aperture Radar along-track interferometry (SAR-ATI) an End-to-End simulator has been developed. The simulator, built in a high modular way to allow easy integration of different processing-features, deals with all the basic operations involved in an end to end scenario. This includes the computation of the position and velocity of the platform (airborne/spaceborne) and the geometric parameters defining the SAR scene, the surface definition, the backscattering computation, the atmospheric attenuation, the instrument configuration, and the simulation of the transmission/reception chains and the raw data. In addition, the simulator provides a inSAR processing suit and a sea surface movement retrieval module. Up to four beams (each one composed by a monostatic and a bistatic channel) can be activated. Each channel provides raw data and SLC images with the possibility of choosing between Strip-map and Scansar modes. Moreover, the software offers the possibility of radiometric sensitivity analysis and error analysis due atmospheric disturbances, instrument-noise, interferogram phase-noise, platform velocity and attitude variations. In this paper, the architecture and the capabilities of this simulator will be presented. Meaningful simulation examples will be shown.
Standardization of transportation classes for object-oriented deployment simulations.
Burke, J. F., Jr.; Howard, D. L.; Jackson, J.; Macal, C. M.; Nevins, M. R.; Van Groningen, C. N.
1999-07-30
Many recent efforts to integrate transportation and deployment simulations, although beneficial, have lacked a feature vital for seamless integration: a common data class representation. It is an objective of the Department of Defense (DoD) to standardize all classes used in object-oriented deployment simulations by developing a standard class attribute representation and behavior for all deployment simulations that rely on an underlying class representation. The Extensive Hierarchy and Object Representation for Transportation Simulations (EXHORT) is a collection of three hierarchies that together will constitute a standard and consistent class attribute representation and behavior that could be used directly by a large set of deployment simulations. The first hierarchy is the Transportation Class Hierarchy (TCH), which describes a significant portion of the defense transportation system; the other two deal with infrastructure and resource classes. EXHORT will allow deployment simulations to use the same set of underlying class data, ensure transparent exchanges, reduce the effort needed to integrate simulations, and permit a detailed analysis of the defense transportation system. This paper describes EXHORT's first hierarchy, the TCH, and provides a rationale for why it is a helpful tool for modeling major portions of the defense transportation system.
Ion internal transport barrier in neutral beam heated plasmas on HL-2A
NASA Astrophysics Data System (ADS)
Yu, D. L.; Wei, Y. L.; Liu, L.; Dong, J. Q.; Ida, K.; Itoh, K.; Sun, A. P.; Cao, J. Y.; Shi, Z. B.; Wang, Z. X.; Xiao, Y.; Yuan, B. S.; Du, H. R.; He, X. X.; Chen, W. J.; Ma, Q.; Itoh, S.-I.; Zhao, K. J.; Zhou, Y.; Wang, J.; Ji, X. Q.; Zhong, W. L.; Li, Y. G.; Gao, J. M.; Deng, W.; Liu, Yi; Xu, Y.; Yan, L. W.; Yang, Q. W.; Ding, X. T.; Duan, X. R.; Liu, Yong; HL-2A Team
2016-05-01
Ion internal transport barriers (iITBs) are first observed in neutral beam injection (NBI) heated plasmas at the HL-2A tokamak. The position of the barrier foot, in the stationary state, coincides with the q = 1 surface within its uncertainty of measurement. iITBs can develop more easily at the beginning of NBI heating. Also, iITBs are unstable for the sawtooth plasma. Simulations reveal that the thermal diffusivity of ions (χ i) inside the barrier can be as low as the neoclassical level. It is observed that the flow shear in the stationary iITB state reaches the level required for suppressing the ion temperature gradient mode instability, which indicates the important role of flow shear in sustaining the iITB.
Theory and Simulation of Neoclassical Transport Processes, with Local Trapping
Dubin, Daniel H. E.
2009-03-30
Neoclassical transport is studied using idealized simulations that follow guiding centers in given fields, neglecting collective effects on the plasma evolution, but including collisions at rate {nu}. For simplicity the magnetic field is assumed to be uniform; transport is due to asymmetries in applied electrostatic fields. Also, the Fokker-Planck equation describing the particle distribution is solved, and the predicted transport is found to agree with the simulations. Banana, plateau, and fluid regimes are identified and observed in the simulations. When separate trapped particle populations are created by application of an axisymmetric squeeze potential, enhanced transport regimes are observed, scaling as {radical}({nu}) when {nu}<{omega}{sub 0}<{omega}{sub b} and as 1/{nu} when {omega}{sub 0}<{nu}<{omega}{sub b} where {omega}{sub 0} and {omega}{sub b} are the rotation and axial bounce frequencies, respectively. These regimes are similar to those predicted for neoclassical transport in stellarators.
Gyrokinetic and global fluid simulations of tokamak microturbulence and transport
Dimits, A.M.; Byers, J.A.; Williams, T.J.; Cohen, B.I.; Xu, W.Q.; Cohen, R.H.; Crotinger, J.A.; Shestakov, A.I.
1994-08-30
Results are presented from the first systematic nonlinear kinetic simulation study of the swings and parameter dependences of toroidal ion-temperature-gradient (ITG) turbulence and transport, and from the first such study that includes sheared toroidal flows. Key results include the observation of clear gyroBohm scaling of the turbulent transport and of a surprisingly weak dependence of the transport on toroidal flow shear. Based on the simulation results, a parameterization of the transport is given that includes the dependence on all of the relevant physical parameters. The transition from local to nonlocal transport as a function of the profile scale length has been investigated using two-dimensional global fluid simulations of dissipative drift-wave turbulence. Local gyroBohm scaling is observed, except at very short profile scale lengths.
Investigating the accuracy of the FLUKA code for transport of therapeutic ion beams in matter.
Sommerer, Florian; Parodi, Katia; Ferrari, Alfredo; Poljanc, Karin; Enghardt, Wolfgang; Aiginger, Hannes
2006-09-01
In-beam positron emission tomography (PET) is currently used for monitoring the dose delivery at the heavy ion therapy facility at GSI Darmstadt. The method is based on the fact that carbon ions produce positron emitting isotopes in fragmentation reactions with the atomic nuclei of the tissue. The relation between dose and beta(+)-activity is not straightforward. Hence it is not possible to infer the delivered dose directly from the PET distribution. To overcome this problem and enable therapy monitoring, beta(+)-distributions are simulated on the basis of the treatment plan and compared with the measured ones. Following the positive clinical impact, it is planned to apply the method at future ion therapy facilities, where beams from protons up to oxygen nuclei will be available. A simulation code capable of handling all these ions and predicting the irradiation-induced beta(+)-activity distributions is desirable. An established and general purpose radiation transport code is preferred. FLUKA is a candidate for such a code. For application to in-beam PET therapy monitoring, the code has to model with high accuracy both the electromagnetic and nuclear interactions responsible for dose deposition and beta(+)-activity production, respectively. In this work, the electromagnetic interaction in FLUKA was adjusted to reproduce the same particle range as from the experimentally validated treatment planning software TRiP, used at GSI. Furthermore, projectile fragmentation spectra in water targets have been studied in comparison to available experimental data. Finally, cross sections for the production of the most abundant fragments have been calculated and compared to values found in the literature. PMID:16912388
NASA Astrophysics Data System (ADS)
Kikuchi, T.; Sakai, Y.; Komori, T.; Sato, T.; Hasegawa, J.; Horioka, K.; Takahashi, K.; Sasaki, T.; Harada, Nob
2016-05-01
Tune depression in a compact beam equipment is estimated, and numerical simulation results are compared with an experimental one for the compact beam simulator in a driver of heavy ion inertial fusion. The numerical simulation with multi-particle tracking is carried out, corresponding to the experimental condition, and the result is discussed with the experimental one. It is expected that the numerical simulation developed in this paper is useful tool to investigate the beam dynamics in the experiment with the compact beam simulator.
Crossed fiber optic Bessel beams for curvilinear optofluidic transport of dielectric particles.
Kim, Jongki; Lee, Sungrae; Jeong, Yoonseob; Kim, Jun-Ki; Jung, Yongmin; Merenda, Fabrice; Salathè, Renè-Paul; Shin, Jeon-Soo; Oh, Kyunghwan
2013-10-01
Due to its unique non-diffracting and self-reconstructing nature, Bessel beams have been successfully adopted to trap multiple particles along the beam's axial direction. However, prior bulk-optic based Bessel beams have a fundamental form-factor limitation for in situ, in-vitro, and in-vivo applications. Here we present a novel implementation of Fourier optics along a single strand of hybrid optical fiber in a monolithic manner that can generate pseudo Bessel beam arrays in two-dimensional space. We successfully demonstrate unique optofluidic transport of the trapped dielectric particles along a curvilinear optical route by multiplexing the fiber optic pseudo Bessel beams. The proposed technique can form a new building block to realize reconfigurable optofluidic transportation of particulates that can break the limitations of both prior bulk-optic Bessel beam generation techniques and conventional microfluidic channels. PMID:24104217
Impact of beam transport method on chamber and driver design for heavy ion inertial fusion energy
Rose, D.V.; Welch, D.R.; Olson, C.L.; Yu, S.S.; Neff, S.; Sharp, W.M.
2002-12-01
In heavy ion inertial fusion energy systems, intense beams of ions must be transported from the exit of the final focus magnet system through the target chamber to hit millimeter spot sizes on the target. In this paper, we examine three different modes of beam propagation: neutralized ballistic transport, assisted pinched transport, and self-pinched transport. The status of our understanding of these three modes is summarized, and the constraints imposed by beam propagation upon the chamber environment, as well as their compatibility with various chamber and target concepts, are considered. We conclude that, on the basis of our present understanding, there is a reasonable range of parameter space where beams can propagate in thick-liquid wall, wetted-wall, and dry-wall chambers.
Simulation models for conservative and nonconservative solute transport in streams
Runkel, R.L.
1995-01-01
Solute transport in streams is governed by a suite of hydrologic and chemical processes. Interactions between hydrologic processes and chemical reactions may be quantified through a combination of field-scale experimentation and simulation modeling. Two mathematical models that simulate conservative and nonconservative solute transport in streams are presented. A model for conservative solutes that considers One Dimensional Transport with Inflow and Storage (OTIS) may be used in conjunction with tracer-dilution methods to quantify hydrologic transport processes (advection, dispersion, lateral inflow and transient storage). For nonconservative solutes, a model known as OTEQ may be used to quantify chemical processes within the context of hydrologic transport. OTEQ combines the transport mechanisms in OTIS with a chemical equilibrium sub-model that considers complexation, precipitation/dissolution and sorption. OTEQ has been used to quantify processes affecting trace metals in two streams in the Rocky Mountains of Colorado, USA.
NUMERICAL SIMULATION OF POLLUTANT TRANSPORT FROM FISH FARMING IN RIVER
NASA Astrophysics Data System (ADS)
Tran Thi Ngoc, Trieu; Le Song, Giang; Lu, Minjiao
This paper presented a 3D model for substance transport in river and its application for simulation of pollutant transport in Mekong river due to floating cages-raising. 3D flow-field was solved by logarithmic distributing 2D flow-field of averaged height. Pollutant transport is calculated by solving its full 3D transport equation. The 2D continuum and momentum equations were solved by finite difference method with ADI scheme of Ponce-Yabusaki. The 3D transport equation was solved by finite volume method with ADI scheme of Douglas-Gunn in "sigma" transformed co-ordinate. The model was tested over analytical solution. Some preliminary results of simulation for pollutant transport of Myhoahung floating cages area (Angiang province) are also presented.
The Electron Transport Chain: An Interactive Simulation
ERIC Educational Resources Information Center
Romero, Chris; Choun, James
2014-01-01
This activity provides students an interactive demonstration of the electron transport chain and chemiosmosis during aerobic respiration. Students use simple, everyday objects as hydrogen ions and electrons and play the roles of the various proteins embedded in the inner mitochondrial membrane to show how this specific process in cellular…
Plasma confinement theory and transport simulation
Ross, D.W.
1993-02-01
The objectives continue to be: (1) to advance the transport studies of tokamaks, including development and maintenance of the Magnetic Fusion Energy Database, and (2) to provide theoretical interpretation, modeling and equilibrium and stability for TEXT-Upgrade. Recent publications and reports, and conference presentations of the Fusion Research Center theory group are listed.
Space-charged-induced emittance growth in the transport of high-brightness electron beams
Jones, M.E.; Carlsten, B.E.
1987-03-01
The emittance induced by space charge in a drifting beam of finite length has been investigated, and a scaling law has been obtained from simple considerations of the different rates of expansion of different portions of the beam. The scaling law predicts the initial rate of emittance growth, before the beam shape has distorted significantly, and thus represents an upper bound on the rate of emittance increase. This scaling law has been substantiated by particle-in-cell simulation and the dependence on geometric factors evaluated for specific choices of the beam profile. For long, axially nonuniform beams, the geometric factors have been evaluated explicitly for Gaussian profiles, and other shapes.
Collaborative Research: Instability and transport of laser beam in plasma
Rose, Harvey Arnold; Lushnikov, Pavel
2014-11-18
Our goal was to determine the onset of laser light scattering due to plasma wave instabilities. Such scatter is usually regarded as deleterious since laser beam strength is thereby diminished. While this kind of laser-plasma-instability (LPI) has long been understood for the case of coherent laser light, the theory of LPI onset for a laser beam with degraded coherence is recent. Such a laser beam fills plasma with a mottled intensity distribution, which has large fluctuations. The key question is: do the exceptionally large fluctuations control LPI onset or is it controlled by the relatively quiescent background laser intensity? We have answered this question. This is significant because LPI onset power in the former case is typically small compared to that of the latter. In addition, if large laser intensity fluctuations control LPI onset, then nonlinear effects become significant for less powerful laser beams than otherwise estimated.
Absolute dose calculations for Monte Carlo simulations of radiotherapy beams.
Popescu, I A; Shaw, C P; Zavgorodni, S F; Beckham, W A
2005-07-21
Monte Carlo (MC) simulations have traditionally been used for single field relative comparisons with experimental data or commercial treatment planning systems (TPS). However, clinical treatment plans commonly involve more than one field. Since the contribution of each field must be accurately quantified, multiple field MC simulations are only possible by employing absolute dosimetry. Therefore, we have developed a rigorous calibration method that allows the incorporation of monitor units (MU) in MC simulations. This absolute dosimetry formalism can be easily implemented by any BEAMnrc/DOSXYZnrc user, and applies to any configuration of open and blocked fields, including intensity-modulated radiation therapy (IMRT) plans. Our approach involves the relationship between the dose scored in the monitor ionization chamber of a radiotherapy linear accelerator (linac), the number of initial particles incident on the target, and the field size. We found that for a 10 x 10 cm2 field of a 6 MV photon beam, 1 MU corresponds, in our model, to 8.129 x 10(13) +/- 1.0% electrons incident on the target and a total dose of 20.87 cGy +/- 1.0% in the monitor chambers of the virtual linac. We present an extensive experimental verification of our MC results for open and intensity-modulated fields, including a dynamic 7-field IMRT plan simulated on the CT data sets of a cylindrical phantom and of a Rando anthropomorphic phantom, which were validated by measurements using ionization chambers and thermoluminescent dosimeters (TLD). Our simulation results are in excellent agreement with experiment, with percentage differences of less than 2%, in general, demonstrating the accuracy of our Monte Carlo absolute dose calculations. PMID:16177516
Absolute dose calculations for Monte Carlo simulations of radiotherapy beams
NASA Astrophysics Data System (ADS)
Popescu, I. A.; Shaw, C. P.; Zavgorodni, S. F.; Beckham, W. A.
2005-07-01
Monte Carlo (MC) simulations have traditionally been used for single field relative comparisons with experimental data or commercial treatment planning systems (TPS). However, clinical treatment plans commonly involve more than one field. Since the contribution of each field must be accurately quantified, multiple field MC simulations are only possible by employing absolute dosimetry. Therefore, we have developed a rigorous calibration method that allows the incorporation of monitor units (MU) in MC simulations. This absolute dosimetry formalism can be easily implemented by any BEAMnrc/DOSXYZnrc user, and applies to any configuration of open and blocked fields, including intensity-modulated radiation therapy (IMRT) plans. Our approach involves the relationship between the dose scored in the monitor ionization chamber of a radiotherapy linear accelerator (linac), the number of initial particles incident on the target, and the field size. We found that for a 10 × 10 cm2 field of a 6 MV photon beam, 1 MU corresponds, in our model, to 8.129 × 1013 ± 1.0% electrons incident on the target and a total dose of 20.87 cGy ± 1.0% in the monitor chambers of the virtual linac. We present an extensive experimental verification of our MC results for open and intensity-modulated fields, including a dynamic 7-field IMRT plan simulated on the CT data sets of a cylindrical phantom and of a Rando anthropomorphic phantom, which were validated by measurements using ionization chambers and thermoluminescent dosimeters (TLD). Our simulation results are in excellent agreement with experiment, with percentage differences of less than 2%, in general, demonstrating the accuracy of our Monte Carlo absolute dose calculations.
Fast Monte Carlo for ion beam analysis simulations
NASA Astrophysics Data System (ADS)
Schiettekatte, François
2008-04-01
A Monte Carlo program for the simulation of ion beam analysis data is presented. It combines mainly four features: (i) ion slowdown is computed separately from the main scattering/recoil event, which is directed towards the detector. (ii) A virtual detector, that is, a detector larger than the actual one can be used, followed by trajectory correction. (iii) For each collision during ion slowdown, scattering angle components are extracted form tables. (iv) Tables of scattering angle components, stopping power and energy straggling are indexed using the binary representation of floating point numbers, which allows logarithmic distribution of these tables without the computation of logarithms to access them. Tables are sufficiently fine-grained that interpolation is not necessary. Ion slowdown computation thus avoids trigonometric, inverse and transcendental function calls and, as much as possible, divisions. All these improvements make possible the computation of 107 collisions/s on current PCs. Results for transmitted ions of several masses in various substrates are well comparable to those obtained using SRIM-2006 in terms of both angular and energy distributions, as long as a sufficiently large number of collisions is considered for each ion. Examples of simulated spectrum show good agreement with experimental data, although a large detector rather than the virtual detector has to be used to properly simulate background signals that are due to plural collisions. The program, written in standard C, is open-source and distributed under the terms of the GNU General Public License.
Stable two-plane focusing for emittance-dominated sheet-beam transport
NASA Astrophysics Data System (ADS)
Carlsten, B. E.; Earley, L. M.; Krawczyk, F. L.; Russell, S. J.; Potter, J. M.; Ferguson, P.; Humphries, S.
2005-06-01
Two-plane focusing of sheet electron beams will be an essential technology for an emerging class of high-power, 100 to 300 GHz rf sources [Carlsten et al., IEEE Trans. Plasma Sci. 33, 85 (2005), ITPSBD, 0093-3813, 10.1109/TPS.2004.841172]. In these devices, the beam has a unique asymmetry in which the transport is emittance dominated in the sheet’s thin dimension and space-charge dominated in the sheet’s wide dimension. Previous work has studied the stability of the transport of beams in the emittance-dominated regime for both wiggler and periodic permanent magnet (PPM) configurations with single-plane focusing, and has found that bigger envelope scalloping occurs for equilibrium transport, as compared to space-charge dominated beams [Carlsten et al., this issue, Phys. Rev. ST Accel. Beams 8, 062001 (2005), PRABFM, 1098-4402]. In this paper, we describe the differences in transport stability when two-plane focusing is included. Two-plane wiggler focusing degrades the transport stability slightly, whereas two-plane PPM focusing greatly compromises the transport. On the other hand, single-plane PPM focusing can be augmented with external quadrupole fields to provide weak focusing in the sheet’s wide dimension, which has stability comparable to two-plane wiggler transport.
Drift-Kinetic Simulations of Neoclassical Transport
Belli, E. A.; Candy, J.
2008-11-01
We present results from numerical studies of neoclassical transport for multi-species plasmas. The code, NEO, provides a first-principles based calculation of the neoclassical transport coefficients directly from solution of the distribution function by solving a hierarchy of equations derived by expanding the fundamental drift-kinetic equation in powers of {rho}{sub *i}, the ratio of the ion gyroradius to system size. It extends previous studies by including the self-consistent coupling of electrons and multiple ion species and strong toroidal rotation effects. Systematic calculations of the second-order particle and energy fluxes and first-order plasma flows and bootstrap current and comparisons with existing theories are given for multi-species plasmas. The ambipolar relation {sigma}{sub a}z{sub a}{gamma}{sub a} = 0, which can only be maintained with complete cross-species collisional coupling, is confirmed. The effects of plasma shaping are also explored.
Simulation of Airborne Microbial Droplet Transport
Lighthart, Bruce; Kim, Jinwon
1989-01-01
The framework for a simulation model which describes the dispersion of individual droplets of water containing viable microbes is presented. The model accounts for physical, chemical, biological, and measured meteorological parameters of each droplet at each of many short time steps. Repeating the modeling process for many droplets will simulate a cloud of droplets. The model is compared with the Tulelake, Calif., release in 1988 and found to show very similar patterns of deposition within 30 m (the maximum observation distance of the source. A hypothesis for the survival sequence in the microbe-containing droplets is discussed. PMID:16348015
NASA Technical Reports Server (NTRS)
Hueschen, Richard M.
2011-01-01
A six degree-of-freedom, flat-earth dynamics, non-linear, and non-proprietary aircraft simulation was developed that is representative of a generic mid-sized twin-jet transport aircraft. The simulation was developed from a non-proprietary, publicly available, subscale twin-jet transport aircraft simulation using scaling relationships and a modified aerodynamic database. The simulation has an extended aerodynamics database with aero data outside the normal transport-operating envelope (large angle-of-attack and sideslip values). The simulation has representative transport aircraft surface actuator models with variable rate-limits and generally fixed position limits. The simulation contains a generic 40,000 lb sea level thrust engine model. The engine model is a first order dynamic model with a variable time constant that changes according to simulation conditions. The simulation provides a means for interfacing a flight control system to use the simulation sensor variables and to command the surface actuators and throttle position of the engine model.
Particle beam dynamics simulations using the POOMA framework
Humphrey, W.; Ryne, R.; Cleland, T.; Cummings, J.; Habib, S.; Mark, G.; Ji Qiang
1998-12-31
A program for simulation of the dynamics of high intensity charged particle beams in linear particle accelerators has been developed in C++ using the POOMA Framework, for use on serial and parallel architectures. The code models the trajectories of charged particles through a sequence of different accelerator beamline elements such as drift chambers, quadrupole magnets, or RF cavities. An FFT-based particle-in-cell algorithm is used to solve the Poisson equation that models the Coulomb interactions of the particles. The code employs an object-oriented design with software abstractions for the particle beam, accelerator beamline, and beamline elements, using C++ templates to efficiently support both 2D and 3D capabilities in the same code base. The POOMA Framework, which encapsulates much of the effort required for parallel execution, provides particle and field classes, particle-field interaction capabilities, and parallel FFT algorithms. The performance of this application running serially and in parallel is compared to an existing HPF implementation, with the POOMA version seen to run four times faster than the HPF code.
Transport of intense proton beams in an induction linac by solenoid lenses
NASA Astrophysics Data System (ADS)
Namkung, W.; Choe, J. Y.; Uhm, H. S.
1986-01-01
In the proposed proton induction linac at NSWC, a 100 A and 3 μs proton beam is accelerated to 5 MeV through a series of accelerating gaps. This beam can be effectively focused by solenoid lenses in this low energy regime and can be transported by adjusting the focusing strength in each period. For the transport channel design to reduce the number of independently controlled lenses, a theory of matched beams in the space-charge dominated regime has been developed. This study can be applied to cost efficient designs of induction accelerators for heavy ion fusion and free electron lasers.
An overview of design for CSNS/RCS and beam transport
NASA Astrophysics Data System (ADS)
Wang, Sheng; An, YuWen; Fang, ShouXian; Huang, Nan; Liu, WeiBin; Liu, YuDong; Qin, Qing; Qiu, Jing; Wang, Na; Xu, Gang; Xu, ShouYan; Yu, ChengHui
2011-12-01
The China Spallation Neutron Source (CSNS) is the first accelerator-based pulsed neutron source in China. Its accelerators are made up of an 80 MeV H- linac, a Rapid Cycling Synchrotron (RCS) and two beam transport lines. RCS accumulates and accelerates protons to the design energy of 1.6 GeV, and extracts high energy beam to strike the target. The overview of RCS is presented, and the key problems of the physics design are discussed. The two beam transport lines, from linac to RCS and from RCS to the target, are also introduced.
Simulations of proton beam characteristics for ELIMED Beamline
NASA Astrophysics Data System (ADS)
Psikal, Jan; Limpouch, Jiri; Klimo, Ondrej; Vyskocil, Jiri; Margarone, Daniele; Korn, Georg
2016-03-01
ELIMED Beamline should demonstrate the capability of laser-based particle accelerators for medical applications, mainly for proton radiotherapy of tumours which requires a sufficient number of accelerated protons with energy about 60 MeV at least. In this contribution, we study the acceleration of protons by laser pulse with parameters accessible for ELIMED Beamline (intensity ∼ 1022 W/cm2, pulse length ∼ 30 fs). In our two-dimensional particle-incell simulations, we observed higher energies of protons for linear than for circular polarization. Oblique incidence of the laser pulse on target does not seem to be favourable for proton acceleration at such high intensities as the accelerated protons are deflected from target normal axis and their energy and numbers are slightly decreased. The expected numbers of accelerated protons in the energy interval 60 MeV ± 5% are calculated between 109 and 1010 per laser shot with estimated proton beam divergence about 20° (FWHM).
Spontaneous ion beam formation in the laboratory, space, and simulation
Carr, J. Jr.; Cassak, P. A.; Galante, M.; Keesee, A. M.; Lusk, G.; Magee, R. M.; McCarren, D.; Scime, E. E.; Sears, S.; Vandervort, R.; Gulbrandsen, N.; Goldman, Martin; Newman, David; Eastwood, J. P.
2013-07-15
We present experimental evidence for the spontaneous formation of multiple double layers within a single divergent magnetic field structure. Downstream of the divergent magnetic field, multiple accelerated ion populations are observed. The similarity of the accelerated ion populations observed in these laboratory experiments to ion populations observed in the magnetosphere and in numerical simulations suggests that the observation of a complex ion velocity distribution alone is insufficient to distinguish between simple plasma expansion and magnetic reconnection. Further, the effective temperature of the aggregate ion population is significantly larger than the temperatures of the individual ion population components, suggesting that insufficiently resolved measurements could misidentify multiple beam creation as ion heating. Ions accelerated in randomly oriented electric fields that mimic heating would have an ion heating rate dependent on the ion charge and mass that is qualitatively consistent with recent experimental observations of ion heating during magnetic reconnection.
Monte Carlo simulation of a cobalt-60 beam
Han, K.; Ballon, D.; Chui, C.; Mohan, R.
1987-05-01
We have used the Stanford Electron Gamma Shower (EGS) Monte Carlo code to compute photon spectra from an AECL Theratron 780 cobalt-60 unit. Particular attention has been paid to the careful modeling of the geometry and material construction of the cobalt-60 source capsule, source housing, and collimator assembly. From our simulation, we conclude that the observed increase in output of the machine with increasing field size is caused by scattered photons from the primary definer and the adjustable collimator. We have also used the generated photon spectra as input to a pencil beam model to calculate the tissue--air ratios in water and compared it to a model which uses a monochromatic photon energy of 1.25 MeV.
Animated simulation of greenhouse internal transport using Siman/Cinema
Fang, W.; Ting, K.C.; Giacomelli, G.A. . Dept. of Biological and Agricultural Engineering)
1990-01-01
This paper reports on an animated computer model developed using a simulation language Sinman/Cinema to simulate greenhouse internal transport systems. The model can be used as a tool to study the performance of materials handling operations within a greenhouse. The potential bottleneck of a transport system can be visually detected on the computer monitor. Statistical analyses on the system parameters, such as the status and utilization of machines, workers and waiting lines, and throughput time of an operation, are performed during the simulation. From these data, the interaction between machines and workers within a greenhouse system can be studied.
Radiative transport produced by oblique illumination of turbid media with collimated beams
Gardner, Adam R.; Kim, Arnold D.; Venugopalan, Vasan
2014-01-01
We examine the general problem of light transport initiated by oblique illumination of a turbid medium with a collimated beam. This situation has direct relevance to the analysis of cloudy atmospheres, terrestrial surfaces, soft condensed matter, and biological tissues. We introduce a novel solution approach to the equation of radiative transfer that governs this problem, and develop a comprehensive spherical harmonics expansion method utilizing Fourier decomposition (SHEFN). The SHEFN approach enables the solution of problems lacking azimuthal symmetry and provides both the spatial and directional dependence of the radiance. We also introduce the method of sequential-order smoothing (SOS) that enables the calculation of accurate solutions from the results of two sequential low-order approximations. We apply the SHEFN approach to determine the spatial and angular dependence of both internal and boundary radiances from strongly- and weakly-scattering turbid media. These solutions are validated using more costly Monte Carlo simulations and reveal important insights regarding the evolution of the radiant field generated by oblique collimated beams spanning ballistic and diffusely-scattering regimes. PMID:23848807
Radiative transport produced by oblique illumination of turbid media with collimated beams.
Gardner, Adam R; Kim, Arnold D; Venugopalan, Vasan
2013-06-01
We examine the general problem of light transport initiated by oblique illumination of a turbid medium with a collimated beam. This situation has direct relevance to the analysis of cloudy atmospheres, terrestrial surfaces, soft condensed matter, and biological tissues. We introduce a solution approach to the equation of radiative transfer that governs this problem, and develop a comprehensive spherical harmonics expansion method utilizing Fourier decomposition (SHEF(N)). The SHEF(N) approach enables the solution of problems lacking azimuthal symmetry and provides both the spatial and directional dependence of the radiance. We also introduce the method of sequential-order smoothing that enables the calculation of accurate solutions from the results of two sequential low-order approximations. We apply the SHEF(N) approach to determine the spatial and angular dependence of both internal and boundary radiances from strongly and weakly scattering turbid media. These solutions are validated using more costly Monte Carlo simulations and reveal important insights regarding the evolution of the radiant field generated by oblique collimated beams spanning ballistic and diffusely scattering regimes. PMID:23848807
Radiative transport produced by oblique illumination of turbid media with collimated beams
NASA Astrophysics Data System (ADS)
Gardner, Adam R.; Kim, Arnold D.; Venugopalan, Vasan
2013-06-01
We examine the general problem of light transport initiated by oblique illumination of a turbid medium with a collimated beam. This situation has direct relevance to the analysis of cloudy atmospheres, terrestrial surfaces, soft condensed matter, and biological tissues. We introduce a solution approach to the equation of radiative transfer that governs this problem, and develop a comprehensive spherical harmonics expansion method utilizing Fourier decomposition (SHEFN). The SHEFN approach enables the solution of problems lacking azimuthal symmetry and provides both the spatial and directional dependence of the radiance. We also introduce the method of sequential-order smoothing that enables the calculation of accurate solutions from the results of two sequential low-order approximations. We apply the SHEFN approach to determine the spatial and angular dependence of both internal and boundary radiances from strongly and weakly scattering turbid media. These solutions are validated using more costly Monte Carlo simulations and reveal important insights regarding the evolution of the radiant field generated by oblique collimated beams spanning ballistic and diffusely scattering regimes.
Lagrangian simulation of multidimensional anomalous transport at the MADE site
NASA Astrophysics Data System (ADS)
Zhang, Yong; Benson, David A.
2008-04-01
Contaminant transport through regional-scale natural geological formations typically exhibits several ``anomalous'' features, including direction-dependent spreading rates, channeling along preferential flow paths, trapping of solute in relatively immobile domains, and/or the local variation of transport speed. Simulating these plume characteristics can be computationally intensive using a traditional advection-dispersion equation (ADE) because anomalous features of transport generally depend on local-scale subsurface properties. Here we develop an alternative simulation approach that solves the full nonlocal, multidimensional, spatiotemporal fractional-order ADE with variable coefficients in a Lagrangian framework using a novel non-Markovian random walk method. This model allows us to simulate anomalous plumes without the need to explicitly define local-scale heterogeneity. The simple model accurately simulates the tritium plume measured at the extensively characterized MADE test site.
Towards a wave theory of charged beam transport: A collection of thoughts
NASA Technical Reports Server (NTRS)
Dattoli, G.; Mari, C.; Torre, A.
1992-01-01
We formulate in a rigorous way a wave theory of charged beam linear transport. The Wigner distribution function is introduced and provides the link with classical mechanics. Finally, the von Neumann equation is shown to coincide with the Liouville equation for the nonlinear transport.
Commissioning of a Varian Clinac iX 6 MV photon beam using Monte Carlo simulation
Dirgayussa, I Gde Eka Yani, Sitti; Haryanto, Freddy; Rhani, M. Fahdillah
2015-09-30
Monte Carlo modelling of a linear accelerator is the first and most important step in Monte Carlo dose calculations in radiotherapy. Monte Carlo is considered today to be the most accurate and detailed calculation method in different fields of medical physics. In this research, we developed a photon beam model for Varian Clinac iX 6 MV equipped with MilleniumMLC120 for dose calculation purposes using BEAMnrc/DOSXYZnrc Monte Carlo system based on the underlying EGSnrc particle transport code. Monte Carlo simulation for this commissioning head LINAC divided in two stages are design head Linac model using BEAMnrc, characterize this model using BEAMDP and analyze the difference between simulation and measurement data using DOSXYZnrc. In the first step, to reduce simulation time, a virtual treatment head LINAC was built in two parts (patient-dependent component and patient-independent component). The incident electron energy varied 6.1 MeV, 6.2 MeV and 6.3 MeV, 6.4 MeV, and 6.6 MeV and the FWHM (full width at half maximum) of source is 1 mm. Phase-space file from the virtual model characterized using BEAMDP. The results of MC calculations using DOSXYZnrc in water phantom are percent depth doses (PDDs) and beam profiles at depths 10 cm were compared with measurements. This process has been completed if the dose difference of measured and calculated relative depth-dose data along the central-axis and dose profile at depths 10 cm is ≤ 5%. The effect of beam width on percentage depth doses and beam profiles was studied. Results of the virtual model were in close agreement with measurements in incident energy electron 6.4 MeV. Our results showed that photon beam width could be tuned using large field beam profile at the depth of maximum dose. The Monte Carlo model developed in this study accurately represents the Varian Clinac iX with millennium MLC 120 leaf and can be used for reliable patient dose calculations. In this commissioning process, the good
Commissioning of a Varian Clinac iX 6 MV photon beam using Monte Carlo simulation
NASA Astrophysics Data System (ADS)
Dirgayussa, I. Gde Eka; Yani, Sitti; Rhani, M. Fahdillah; Haryanto, Freddy
2015-09-01
Monte Carlo modelling of a linear accelerator is the first and most important step in Monte Carlo dose calculations in radiotherapy. Monte Carlo is considered today to be the most accurate and detailed calculation method in different fields of medical physics. In this research, we developed a photon beam model for Varian Clinac iX 6 MV equipped with MilleniumMLC120 for dose calculation purposes using BEAMnrc/DOSXYZnrc Monte Carlo system based on the underlying EGSnrc particle transport code. Monte Carlo simulation for this commissioning head LINAC divided in two stages are design head Linac model using BEAMnrc, characterize this model using BEAMDP and analyze the difference between simulation and measurement data using DOSXYZnrc. In the first step, to reduce simulation time, a virtual treatment head LINAC was built in two parts (patient-dependent component and patient-independent component). The incident electron energy varied 6.1 MeV, 6.2 MeV and 6.3 MeV, 6.4 MeV, and 6.6 MeV and the FWHM (full width at half maximum) of source is 1 mm. Phase-space file from the virtual model characterized using BEAMDP. The results of MC calculations using DOSXYZnrc in water phantom are percent depth doses (PDDs) and beam profiles at depths 10 cm were compared with measurements. This process has been completed if the dose difference of measured and calculated relative depth-dose data along the central-axis and dose profile at depths 10 cm is ≤ 5%. The effect of beam width on percentage depth doses and beam profiles was studied. Results of the virtual model were in close agreement with measurements in incident energy electron 6.4 MeV. Our results showed that photon beam width could be tuned using large field beam profile at the depth of maximum dose. The Monte Carlo model developed in this study accurately represents the Varian Clinac iX with millennium MLC 120 leaf and can be used for reliable patient dose calculations. In this commissioning process, the good criteria of dose
Analytical and simulator study of advanced transport
NASA Technical Reports Server (NTRS)
Levison, W. H.; Rickard, W. W.
1982-01-01
An analytic methodology, based on the optimal-control pilot model, was demonstrated for assessing longitidunal-axis handling qualities of transport aircraft in final approach. Calibration of the methodology is largely in terms of closed-loop performance requirements, rather than specific vehicle response characteristics, and is based on a combination of published criteria, pilot preferences, physical limitations, and engineering judgment. Six longitudinal-axis approach configurations were studied covering a range of handling qualities problems, including the presence of flexible aircraft modes. The analytical procedure was used to obtain predictions of Cooper-Harper ratings, a solar quadratic performance index, and rms excursions of important system variables.
Beam Transport with an Applied-B Diode with Magnetically Injected Anode Plasma
NASA Astrophysics Data System (ADS)
Johnson, D. J.; Lockner, T. R.
1998-11-01
Proton and nitrogen beams generated with a 10-cm-radius extractor diode on the 600kV, 40kA, 100ns RHEPP1 accelerator are observed with shadowboxes, witness plates and Faraday cups to optimize beam transport for IBEST. An active anode plasma was created by a 2μs-risetime B-field from a fast coil that induces an E-field to ionize a gas puff. A second gas puff neutralizes the space charge of the beam during transport through the applied-B-field in the diode. The effects of diagmagnetic motion on the accelerating equipotentals and space-charge blow up at the edges of the annular beam in the 1.5 cm AKG are investigated. Accelerating potentials with a 7-cm-radius convex curvature gave a proton beam energy at a 14-cm-diameter region 50 cm from the anode that is ~ 40% of the energy coupled to the diode. With nitrogen beams ~ 20% of the diode energy is transported to this region when a 10-cm-radius accelerating curvature is used. Studies of beam rotation show that the beam is emitted from plasma that crosses ~ 7 mm of the slow applied-B field in the AKG reducing the effective AKG to ~ 8 mm.
Experimental investigations of plasma lens focusing and plasma channel transport of heavy ion beams
Tauschwitz, T.; Yu, S.S.; Eylon, S.; Reginato, L.; Leemans, W.; Rasmussen, J.O.; Bangerter, R.O.
1995-04-01
Final focusing of ion beams and propagation in a reactor chamber are crucial questions for heavy ion beam driven Fusion. An alternative solution to ballistic quadrupole focusing, as it is proposed in most reactor studies today, is the utilization of the magnetic field produced by a high current plasma discharge. This plasma lens focusing concept relaxes the requirements for low emittance and energy spread of the driver beam significantly and allows to separate the issues of focusing, which can be accomplished outside the reactor chamber, and of beam transport inside the reactor. For focusing a tapered wall-stabilized discharge is proposed, a concept successfully demonstrated at GSI, Germany. For beam transport a laser pre-ionized channel can be used.
Efficient self-consistent quantum transport simulator for quantum devices
Gao, X. Mamaluy, D.; Nielsen, E.; Young, R. W.; Lilly, M. P.; Bishop, N. C.; Carroll, M. S.; Muller, R. P.; Shirkhorshidian, A.
2014-04-07
We present a self-consistent one-dimensional (1D) quantum transport simulator based on the Contact Block Reduction (CBR) method, aiming for very fast and robust transport simulation of 1D quantum devices. Applying the general CBR approach to 1D open systems results in a set of very simple equations that are derived and given in detail for the first time. The charge self-consistency of the coupled CBR-Poisson equations is achieved by using the predictor-corrector iteration scheme with the optional Anderson acceleration. In addition, we introduce a new way to convert an equilibrium electrostatic barrier potential calculated from an external simulator to an effective doping profile, which is then used by the CBR-Poisson code for transport simulation of the barrier under non-zero biases. The code has been applied to simulate the quantum transport in a double barrier structure and across a tunnel barrier in a silicon double quantum dot. Extremely fast self-consistent 1D simulations of the differential conductance across a tunnel barrier in the quantum dot show better qualitative agreement with experiment than non-self-consistent simulations.
Efficient self-consistent quantum transport simulator for quantum devices
NASA Astrophysics Data System (ADS)
Gao, X.; Mamaluy, D.; Nielsen, E.; Young, R. W.; Shirkhorshidian, A.; Lilly, M. P.; Bishop, N. C.; Carroll, M. S.; Muller, R. P.
2014-04-01
We present a self-consistent one-dimensional (1D) quantum transport simulator based on the Contact Block Reduction (CBR) method, aiming for very fast and robust transport simulation of 1D quantum devices. Applying the general CBR approach to 1D open systems results in a set of very simple equations that are derived and given in detail for the first time. The charge self-consistency of the coupled CBR-Poisson equations is achieved by using the predictor-corrector iteration scheme with the optional Anderson acceleration. In addition, we introduce a new way to convert an equilibrium electrostatic barrier potential calculated from an external simulator to an effective doping profile, which is then used by the CBR-Poisson code for transport simulation of the barrier under non-zero biases. The code has been applied to simulate the quantum transport in a double barrier structure and across a tunnel barrier in a silicon double quantum dot. Extremely fast self-consistent 1D simulations of the differential conductance across a tunnel barrier in the quantum dot show better qualitative agreement with experiment than non-self-consistent simulations.
EXPERIMENTS ON LASER AND E-BEAM TRANSPORT AND INTERACTION IN A PLASMA CHANNEL.
POGORELSKY,I.V.; PAVLISHIN,I.V.; BEN-ZVI,I.; ET AL.
2004-09-15
An ablative capillary discharge is installed into a linac beamline and serves as a plasma source for generating and characterizing wakefields. Simultaneously, the electron beam is used as a tool for plasma diagnostics. A high-energy picosecond CO{sub 2} laser channeled within the same capillary strongly affects a counterpropagating electron beam. These observations, supported with simulations, suggest the possibility of manipulating relativistic electron beams by steep plasma channels ponderomotively produced by a laser.
Experiments on Laser and e-Beam Transport and Interaction in a Plasma Channel
Pogorelsky, I.V.; Pavlishin, I.V.; Ben-Zvi, I.; Yakimenko, V.; Kumita, T.; Kamiya, Y.; Zigler, A.; Diublov, A.; Andreev, N.; Bobrova, N.; Sasorov, P.
2004-12-07
An ablative capillary discharge is installed into a linac beamline and serves as a plasma source for generating and characterizing wakefields. Simultaneously, the electron beam is used as a tool for plasma diagnostics. A high-energy picosecond CO2 laser channeled within the same capillary strongly affects a counterpropagating electron beam. These observations, supported with simulations, suggest the possibility of manipulating relativistic electron beams by steep plasma channels ponderomotively produced by a laser.
High Performance Radiation Transport Simulations on TITAN
Baker, Christopher G; Davidson, Gregory G; Evans, Thomas M; Hamilton, Steven P; Jarrell, Joshua J; Joubert, Wayne
2012-01-01
In this paper we describe the Denovo code system. Denovo solves the six-dimensional, steady-state, linear Boltzmann transport equation, of central importance to nuclear technology applications such as reactor core analysis (neutronics), radiation shielding, nuclear forensics and radiation detection. The code features multiple spatial differencing schemes, state-of-the-art linear solvers, the Koch-Baker-Alcouffe (KBA) parallel-wavefront sweep algorithm for inverting the transport operator, a new multilevel energy decomposition method scaling to hundreds of thousands of processing cores, and a modern, novel code architecture that supports straightforward integration of new features. In this paper we discuss the performance of Denovo on the 10--20 petaflop ORNL GPU-based system, Titan. We describe algorithms and techniques used to exploit the capabilities of Titan's heterogeneous compute node architecture and the challenges of obtaining good parallel performance for this sparse hyperbolic PDE solver containing inherently sequential computations. Numerical results demonstrating Denovo performance on early Titan hardware are presented.
Breast tomosynthesis with monochromatic beams: a feasibility study using Monte Carlo simulations
Malliori, A; Bliznakova, K; Sechopoulos, I; Kamarianakis, Z; Fei, B; Pallikarakis, N
2014-01-01
The aim of the study is to investigate the impact on image quality of using monochromatic beams for lower dose breast tomosynthesis (BT). For this purpose, modeling and simulation of BT and mammography imaging processes have been performed using two x-ray beams: one at 28kVp and a monochromatic at 19keV at different entrance surface air kerma ranging between 0.16 and 5.5 mGy. Two 4cm thick computational breast models in a compressed state were used: one simple homogeneous and one heterogeneous based on CT breast images, with compositions of 50% glandular-50% adipose and 40% glandular-60% adipose tissues by weight, respectively. Modeled lesions representing masses and calcifications were inserted within these breast phantoms. X-ray transport in the breast models was simulated with previously developed and validated Monte Carlo application. Results showed that for the same incident photon fluence, the use of the monochromatic beam in BT resulted in higher image quality compared to the one using polychromatic acquisition, especially in terms of contrast. For the homogenous phantom, the improvement ranged between 15% and 22% for calcifications and masses, respectively, while for the heterogeneous one this improvement was in the order of 33% for the masses and 17% for the calcifications. For different exposures, comparable image quality in terms of signal-difference-to-noise ratio and higher contrast for all features was obtained when using monochromatic 19keV beam at lower mean glandular dose compared to the polychromatic one. Monochromatic images provide also better detail and in combination with BT can lead to substantial improvement in visualization of features and particularly better edge detection of low-contrast masses. PMID:25082791
Breast tomosynthesis with monochromatic beams: a feasibility study using Monte Carlo simulations
NASA Astrophysics Data System (ADS)
Malliori, A.; Bliznakova, K.; Sechopoulos, I.; Kamarianakis, Z.; Fei, B.; Pallikarakis, N.
2014-08-01
The aim of this study is to investigate the impact on image quality of using monochromatic beams for lower dose breast tomosynthesis (BT). For this purpose, modeling and simulation of BT and mammography imaging processes have been performed using two x-ray beams: one at 28 kVp and a monochromatic one at 19 keV at different entrance surface air kerma ranging between 0.16 and 5.5 mGy. Two 4 cm thick computational breast models, in a compressed state, were used: one simple homogeneous and one heterogeneous based on CT breast images, with compositions of 50% glandular-50% adipose and 40% glandular-60% adipose tissues by weight, respectively. Modeled lesions, representing masses and calcifications, were inserted within these breast phantoms. X-ray transport in the breast models was simulated with previously developed and validated Monte Carlo application. Results showed that, for the same incident photon fluence, the use of the monochromatic beam in BT resulted in higher image quality compared to the one using polychromatic acquisition, especially in terms of contrast. For the homogenous phantom, the improvement ranged between 15% and 22% for calcifications and masses, respectively, while for the heterogeneous one this improvement was in the order of 33% for the masses and 17% for the calcifications. For different exposures, comparable image quality in terms of signal-difference-to-noise ratio and higher contrast for all features was obtained when using a monochromatic 19 keV beam at a lower mean glandular dose, compared to the polychromatic one. Monochromatic images also provide better detail and, in combination with BT, can lead to substantial improvement in visualization of features, and particularly better edge detection of low-contrast masses.
Breast tomosynthesis with monochromatic beams: a feasibility study using Monte Carlo simulations.
Malliori, A; Bliznakova, K; Sechopoulos, I; Kamarianakis, Z; Fei, B; Pallikarakis, N
2014-08-21
The aim of this study is to investigate the impact on image quality of using monochromatic beams for lower dose breast tomosynthesis (BT). For this purpose, modeling and simulation of BT and mammography imaging processes have been performed using two x-ray beams: one at 28 kVp and a monochromatic one at 19 keV at different entrance surface air kerma ranging between 0.16 and 5.5 mGy. Two 4 cm thick computational breast models, in a compressed state, were used: one simple homogeneous and one heterogeneous based on CT breast images, with compositions of 50% glandular-50% adipose and 40% glandular-60% adipose tissues by weight, respectively. Modeled lesions, representing masses and calcifications, were inserted within these breast phantoms. X-ray transport in the breast models was simulated with previously developed and validated Monte Carlo application. Results showed that, for the same incident photon fluence, the use of the monochromatic beam in BT resulted in higher image quality compared to the one using polychromatic acquisition, especially in terms of contrast. For the homogenous phantom, the improvement ranged between 15% and 22% for calcifications and masses, respectively, while for the heterogeneous one this improvement was in the order of 33% for the masses and 17% for the calcifications. For different exposures, comparable image quality in terms of signal-difference-to-noise ratio and higher contrast for all features was obtained when using a monochromatic 19 keV beam at a lower mean glandular dose, compared to the polychromatic one. Monochromatic images also provide better detail and, in combination with BT, can lead to substantial improvement in visualization of features, and particularly better edge detection of low-contrast masses. PMID:25082791
Garcia-Pareja, S.; Galan, P.; Manzano, F.; Brualla, L.; Lallena, A. M.
2010-07-15
Purpose: In this work, the authors describe an approach which has been developed to drive the application of different variance-reduction techniques to the Monte Carlo simulation of photon and electron transport in clinical accelerators. Methods: The new approach considers the following techniques: Russian roulette, splitting, a modified version of the directional bremsstrahlung splitting, and the azimuthal particle redistribution. Their application is controlled by an ant colony algorithm based on an importance map. Results: The procedure has been applied to radiosurgery beams. Specifically, the authors have calculated depth-dose profiles, off-axis ratios, and output factors, quantities usually considered in the commissioning of these beams. The agreement between Monte Carlo results and the corresponding measurements is within {approx}3%/0.3 mm for the central axis percentage depth dose and the dose profiles. The importance map generated in the calculation can be used to discuss simulation details in the different parts of the geometry in a simple way. The simulation CPU times are comparable to those needed within other approaches common in this field. Conclusions: The new approach is competitive with those previously used in this kind of problems (PSF generation or source models) and has some practical advantages that make it to be a good tool to simulate the radiation transport in problems where the quantities of interest are difficult to obtain because of low statistics.
COMPARISON OF SIMULATION CODES FOR MICROWAVE INSTABILITY IN BUNCHED BEAMS
Bane, K.L.F.; Cai, Y.; Stupakov, G.; /SLAC
2010-08-25
In accelerator design, there is often a need to evaluate the threshold to the (longitudinal) microwave instability for a bunched beam in an electron storage ring. Several computational tools are available that allow them, once given the wakefield representing a ring, to numerically find the threshold current and to simulate the development of the instability. In this work, they present results of coputer simulations using two codes recently developed at the SLAC National Accelerator Laboratory: a Vlasov-Fokker-Planck (VFP) solver based on an algorithm by Warnock and Ellison, and a program that find the threshold from the linearized Vlasov equation. They apply the programs to find the instability threshold for three models of ring impedances: that of a Q = 1 resonator, of shielded coherent synchrotron radiation (CSR), and of a resistive wall. The first example is wel-bheaved, but the other two are singular wakes that need special care. Note that similar numerical studies of the threshold of a Q = 1 resonantor wake have been performed by Oide and Yokova, and others. They compare the results of the two programs and discuss their respective capabilities and limitations. In this report they assume the slippage factor {eta} is always positive. They work in Gaussian units.
Simulations of ion beams for NDCX-II
NASA Astrophysics Data System (ADS)
Grote, D. P.; Friedman, A.; Sharp, W. M.
2014-01-01
NDCX-II, the second neutralized drift compression experiment, is a moderate energy, high current accelerator designed to drive targets for warm dense matter and IFE-relevant energy coupling studies, and to serve as a testbed for high current accelerator physics. As part of the design process, studies were carried out to assess the sensitivities of the accelerator to errors, and to further optimize the design in concert with the evolving pulsed power engineering. The Warp code was used to carry out detailed simulations in both axisymmetric and full 3-D geometry. Ensembles of simulations were carried out to characterize the effects of errors, such as timing jitter and noise on the accelerator waveforms, noise on the source waveform, and solenoid and source offsets. In some cases, the ensemble studies resulted in better designs, revealing operating points with improved performance and showing possible means for further improvement. These studies also revealed a new non-paraxial effect of the final focus solenoid on the beam, which must be taken into account in designing an optimal final focusing system.
Arrow 227: Air transport system design simulation
NASA Technical Reports Server (NTRS)
Bontempi, Michael; Bose, Dave; Brophy, Georgeann; Cashin, Timothy; Kanarios, Michael; Ryan, Steve; Peterson, Timothy
1992-01-01
The Arrow 227 is a student-designed commercial transport for use in a overnight package delivery network. The major goal of the concept was to provide the delivery service with the greatest potential return on investment. The design objectives of the Arrow 227 were based on three parameters; production cost, payload weight, and aerodynamic efficiency. Low production cost helps to reduce initial investment. Increased payload weight allows for a decrease in flight cycles and, therefore, less fuel consumption than an aircraft carrying less payload weight and requiring more flight cycles. In addition, fewer flight cycles will allow a fleet to last longer. Finally, increased aerodynamic efficiency in the form of high L/D will decrease fuel consumption.
Simulation studies of air transport operational problems
NASA Technical Reports Server (NTRS)
Lauber, J. K.; Billings, C. E.; Stevenson, J. E.; Ruffell-Smith, H. P.; Cooper, G. E.
1976-01-01
An experimental evaluation of the monitored approach procedure for conducting low visibility instrument approaches is described. Four airline crews each flew 16 approaches using the monitored procedure and 16 using a modified standard procedure in a DC-10 simulator under various conditions of visibility, wind shear and turbulence, and radar vectoring scenarios. In terms of system measures of aircrew performance, no major differences were found. Pilot opinion data indicate that there are some desirable characteristics of the monitored procedure, particularly with reference to the increased role of the flight engineer in conducting low visibility approaches. Rationale for developing approach procedures is discussed.
Charge neutralized low energy beam transport at Brookhaven 200 MeV linac
NASA Astrophysics Data System (ADS)
Raparia, D.; Alessi, J.; Atoian, G.; Zelenski, A.
2016-02-01
The H- magnetron source provides about 100 mA H- beam to be match into the radio-frequency quadrupole accelerator. As H- beam traverses through low energy transport, it ionizes the residual gas and electrons are repelled and positive ions are trapped in the beam, due to negative potential of the beam, providing charge neutralization for the H- beam. The neutralization time for the critical density depends upon the background gas and its pressure. Critical density for xenon gas at 35 keV is about 43 times smaller than that of hydrogen and stripping cross section is only 5 times than that of hydrogen gas. We are using xenon gas to reduce neutralization time and to improve transmission through the 200 MeV linac. We are also using pulse nitrogen gas to improve transmission and stability of polarized H- beam from optically pumped polarized ion source.
Charge neutralized low energy beam transport at Brookhaven 200 MeV linac.
Raparia, D; Alessi, J; Atoian, G; Zelenski, A
2016-02-01
The H(-) magnetron source provides about 100 mA H(-) beam to be match into the radio-frequency quadrupole accelerator. As H(-) beam traverses through low energy transport, it ionizes the residual gas and electrons are repelled and positive ions are trapped in the beam, due to negative potential of the beam, providing charge neutralization for the H(-) beam. The neutralization time for the critical density depends upon the background gas and its pressure. Critical density for xenon gas at 35 keV is about 43 times smaller than that of hydrogen and stripping cross section is only 5 times than that of hydrogen gas. We are using xenon gas to reduce neutralization time and to improve transmission through the 200 MeV linac. We are also using pulse nitrogen gas to improve transmission and stability of polarized H(-) beam from optically pumped polarized ion source. PMID:26932107
The mechanical design for the second axis beam transport line for the DARHT facility
Bertolini, L R; Alford, O J; Paul, A C; Shang, C C; Westenkow, G A
1999-03-23
This paper describes the mechanical design of the downstream beam transport line for the second axis of the Dual Axis Radiographic Hydrodynamic Test (DARHT II) facility. The DARHT II project is a collaboration between LANL, LBNL, and LLNL. DARHT II is a 20-MeV, 2000-Amperes, 2-µsec pulse length linear induction accelerator designed to generate short bursts of x-rays for the purpose of radiographing dense objects. The downstream beam transport line is an 18-meter long region extending from the end of the accelerator to the bremsstrahlung target. Within this proposed transport line there are 17 conventional solenoid, quadrupole and dipole magnets; as well as several specialty magnets, which transport and focus the beam to the target and beam dumps. There is a high power beam dump, which is designed to absorb the 80-kJ of beam energy during accelerator start-up and operation. The beamline vacuum chamber has an 8-cm diameter aperture and operates at an average pressure of 10^{-7} Torr.
Simulation of transportation of low enriched uranium solutions
Hope, E.P.; Ades, M.J.
1996-08-01
A simulation of the transportation by truck of low enriched uranium solutions has been completed for NEPA purposes at the Savannah River Site. The analysis involves three distinct source terms, and establishes the radiological risks of shipment to three possible destinations. Additionally, loading accidents were analyzed to determine the radiological consequences of mishaps during handling and delivery. Source terms were developed from laboratory measurements of chemical samples from low enriched uranium feed materials being stored at SRS facilities, and from manufacturer data on transport containers. The transportation simulations were accomplished over the INTERNET using the DOE TRANSNET system at Sandia National Laboratory. The HIGHWAY 3.3 code was used to analyze routing scenarios, and the RADTRAN 4 code was used to analyze incident free and accident risks of transporting radiological materials. Loading accidents were assessed using the Savannah River Site AXAIR89Q and RELEASE 2 codes.
The dynamics of iterated transportation simulations
Nagel, K.; Rickert, M.; Simon, P.M.
1998-12-01
Transportation-related decisions of people often depend on what everybody else is doing. For example, decisions about mode choice, route choice, activity scheduling, etc., can depend on congestion, caused by the aggregated behavior of others. From a conceptual viewpoint, this consistency problem causes a deadlock, since nobody can start planning because they do not know what everybody else is doing. It is the process of iterations that is examined in this paper as a method for solving the problem. In this paper, the authors concentrate on the aspect of the iterative process that is probably the most important one from a practical viewpoint, and that is the ``uniqueness`` or ``robustness`` of the results. Also, they define robustness more in terms of common sense than in terms of a mathematical formalism. For this, they do not only want a single iterative process to converge, but they want the result to be independent of any particular implementation. The authors run many computational experiments, sometimes with variations of the same code, sometimes with totally different code, in order to see if any of the results are robust against these changes.
Beam dynamics simulations and measurements at the Project X Test Facility
Gianfelice-Wendt, E.; Scarpine, V.E.; Webber, R.C.; /Fermilab
2011-03-01
Project X, under study at Fermilab, is a multitask high-power superconducting RF proton beam facility, aiming to provide high intensity protons for rare processes experiments and nuclear physics at low energy, and simultaneously for the production of neutrinos, as well as muon beams in the long term. A beam test facility - former known as High Intensity Neutrino Source (HINS) - is under commissioning for testing critical components of the project, e.g. dynamics and diagnostics at low beam energies, broadband beam chopping, RF power generation and distribution. In this paper we describe the layout of the test facility and present beam dynamics simulations and measurements.
Mathematical simulation of sediment and radionuclide transport in estuaries
Onishi, Y.; Trent, D.S.
1982-11-01
The finite element model LFESCOT (Flow, Energy, Salinity, Sediment and Contaminant Transport Model) was synthesized under this study to simulate radionuclide transport in estuaries to obtain accurate radionuclide distributions which are affected by these factors: time variance, three-dimensional flow, temperature, salinity, and sediments. Because sediment transport and radionuclide adsorption/desorption depend strongly on sizes or types of sediments, FLESCOT simulates sediment and a sediment-sorbed radionuclide for the total of three sediment-size fractions (or sediment types) of both cohesive and noncohesive sediments. It also calculates changes of estuarine bed conditions, including bed elevation changes due to sediment erosion/deposition, and three-dimensional distributions of three bed sediment sizes and sediment-sorbed radionuclides within the bed. Although the model was synthesized for radionuclide transport, it is general enough to also handle other contaminants such as heavy metals, pesticides, or toxic chemicals. The model was checked for its capability for flow, water surface elevation change, salinity, sediment and radionuclide transport under various simple conditions first, confirming the general validity of the model's computational schemes. These tests also revealed that FLESCOT can use large aspect ratios of computational cells, which are necessary in handling long estuarine study areas. After these simple tests, FLESCOT was applied to the Hudson River estuary between Chelsea and the mouth of the river to examine how well the model can predict radionuclide transport through simulating tidally influenced three-dimensional flow, salinity, sediment and radionuclide movements with their interactions.
Tsoupas,N.; Ahrens, L.; Pile, P.; Thieberger, P.; Murray, M.M.
2008-10-01
As part of the preparation for the Proton Interrogation Experiment, we have calculated the beam optics for the transport of 4 GeV protons, from the AGS extraction point, to the 'Cross-Section Target Wheel 1' and to the 'Proton Interrogation Target'. In this technical note we present three possible beam-transports each corresponding to a particular Fast Extracted Beam W B setup of the AGS. In addition we present results on the effect of the atmospheric air, (which fills the drift space of the last 100 [m] of the transport line), on the size of the beam, at two locations along the drift space, one location at the middle of the drift space and the other at the end where the 'Proton Interrogation Target' is placed. All the beam transports mentioned above require the removal of the WD1 dipole magnet, which is the first magnet of the W-line, because it acts as a limiting beam aperture, and the magnet is not used in the beam transport. An alternative solution of a beam transport, which does not require the removal of the WD1 magnet, is also presented. In this solution, which models the transport line using the TURTLE computer code[7], the vertical beam sizes at the location of the WD1 magnet is minimized to allow 'lossless' beam transport at the location of the WD1 magnet. A similar solution, but using a MAD model of the line, is also presented.
Lund, Steven M.; Kikuchi, Takashi; Davidson, Ronald C.
2007-04-03
Self-consistent Vlasov-Poisson simulations of beams with high space-charge intensity often require specification of initial phase-space distributions that reflect properties of a beam that is well adapted to the transport channel--both in terms of low-order rms (envelope) properties as well as the higher-order phase-space structure. Here, we first review broad classes of kinetic distributions commonly in use as initial Vlasov distributions in simulations of unbunched or weakly bunched beams with intense space-charge fields including: the Kapchinskij-Vladimirskij (KV) equilibrium, continuous-focusing equilibria with specific detailed examples, and various non-equilibrium distributions, such as the semi-Gaussian distribution and distributions formed from specified functions of linear-field Courant-Snyder invariants. Important practical details necessary to specify these distributions in terms of usual accelerator inputs are presented in a unified format. Building on this presentation, a new class of approximate initial kinetic distributions are constructed using transformations that preserve linear-focusing single-particle Courant-Snyder invariants to map initial continuous-focusing equilibrium distributions to a form more appropriate for non-continuous focusing channels. Self-consistent particle-in-cell simulations are employed to show that the approximate initial distributions generated in this manner are better adapted to the focusing channels for beams with high space-charge intensity. This improved capability enables simulation applications that more precisely probe intrinsic stability properties and machine performance.
Lund, S M; Kikuchi, T; Davidson, R C
2007-04-12
Self-consistent Vlasov simulations of beams with high space-charge intensity often require specification of initial phase-space distributions that reflect properties of a beam that is well adapted to the transport channel, both in terms of low-order rms (envelope) properties as well as the higher-order phase-space structure. Here, we first review broad classes of distributions commonly in use as initial Vlasov distributions in simulations of beams with intense space-charge fields including: the Kapchinskij-Vladimirskij (KV) equilibrium, continuous-focusing equilibria with specific detailed examples, and various non-equilibrium distributions, such as the semi-Gaussian distribution and distributions formed from specified functions of linear-field Courant-Snyder invariants. Important practical details necessary to specify these distributions in terms of usual accelerator inputs are presented in a unified format. Building on this presentation, a new class of approximate initial distributions are constructed using transformations that preserve linear-focusing single-particle Courant-Snyder invariants to map initial continuous-focusing equilibrium distributions to a form more appropriate for non-continuous focusing channels. Self-consistent particle-in-cell simulations are employed to show that the approximate initial distributions generated in this manner are better adapted to the focusing channels for beams with high space-charge intensity. This improved capability enables simulation applications that more precisely probe intrinsic stability properties and machine performance.
Quantum Simulator for Transport Phenomena in Fluid Flows
Mezzacapo, A.; Sanz, M.; Lamata, L.; Egusquiza, I. L.; Succi, S.; Solano, E.
2015-01-01
Transport phenomena still stand as one of the most challenging problems in computational physics. By exploiting the analogies between Dirac and lattice Boltzmann equations, we develop a quantum simulator based on pseudospin-boson quantum systems, which is suitable for encoding fluid dynamics transport phenomena within a lattice kinetic formalism. It is shown that both the streaming and collision processes of lattice Boltzmann dynamics can be implemented with controlled quantum operations, using a heralded quantum protocol to encode non-unitary scattering processes. The proposed simulator is amenable to realization in controlled quantum platforms, such as ion-trap quantum computers or circuit quantum electrodynamics processors. PMID:26278968
Computer Simulations of Ion Transport in Polymer Electrolyte Membranes.
Mogurampelly, Santosh; Borodin, Oleg; Ganesan, Venkat
2016-06-01
Understanding the mechanisms and optimizing ion transport in polymer membranes have been the subject of active research for more than three decades. We present an overview of the progress and challenges involved with the modeling and simulation aspects of the ion transport properties of polymer membranes. We are concerned mainly with atomistic and coarser level simulation studies and discuss some salient work in the context of pure binary and single ion conducting polymer electrolytes, polymer nanocomposites, block copolymers, and ionic liquid-based hybrid electrolytes. We conclude with an outlook highlighting future directions. PMID:27070764
Quantum Simulator for Transport Phenomena in Fluid Flows.
Mezzacapo, A; Sanz, M; Lamata, L; Egusquiza, I L; Succi, S; Solano, E
2015-01-01
Transport phenomena still stand as one of the most challenging problems in computational physics. By exploiting the analogies between Dirac and lattice Boltzmann equations, we develop a quantum simulator based on pseudospin-boson quantum systems, which is suitable for encoding fluid dynamics transport phenomena within a lattice kinetic formalism. It is shown that both the streaming and collision processes of lattice Boltzmann dynamics can be implemented with controlled quantum operations, using a heralded quantum protocol to encode non-unitary scattering processes. The proposed simulator is amenable to realization in controlled quantum platforms, such as ion-trap quantum computers or circuit quantum electrodynamics processors. PMID:26278968
Simulation study of dynamic aperture with head-on beam-beam compensation in the RHIC
Luo, Y.; Fischer, W.
2010-08-01
In this note we summarize the calculated 10{sup 6} turn dynamic apertures with the proposed head-on beam-beam compensation in the Relativistic Heavy Ion Collider (RHIC). To compensate the head-on beam-beam effect in the RHIC 250 GeV polarized proton run, we are planning to introduce a DC electron beam with the same transverse profile as the proton beam to collide with the proton beam. Such a device to provide the electron beam is called an electron lens (e-lens). In this note we first present the optics and beam parameters and the tracking setup. Then we compare the calculated dynamic apertures without and with head-on beam-beam compensation. The effects of adjusted phase advances between IP8 and the center of e-lens and second order chromaticity correction are checked. In the end we will scan the proton and electron beam parameters with head-on beam-beam compensation.
Using TRINET for simulating flow and transport in porous media
Najita, J.; Doughty, C.
1998-08-01
The finite element model TRINET calculates transient or steady-state fluid flow and solute transport on a lattice composed of one-dimensional finite elements (i.e., pipes) of porous medium. TRINET incorporates an adaptive gridding algorithm to minimize numerical dispersion for transport calculations. Although TRINET was originally developed to study fracture networks, the primary interest here is in applying TRINET more generally to simulate transport in porous media (or a fractured medium being treated as an effective continuum). This requires developing expressions to relate TRINET inputs to equivalent parameters used to describe flow and transport in homogeneous porous media. In this report, the authors briefly describe the basic TRINET formulation for flow and transport, present TRINET equivalences for porous medium parameters, and compare TRINET to analytical solutions using the proposed porous medium equivalents.
Neutron transport study of a beam port based dynamic neutron radiography facility
NASA Astrophysics Data System (ADS)
Khaial, Anas M.
Neutron radiography has the ability to differentiate between gas and liquid in two-phase flow due both to the density difference and the high neutron scattering probability of hydrogen. Previous studies have used dynamic neutron radiography -- in both real-time and high-speed -- for air-water, steam-water and gas-liquid metal two-phase flow measurements. Radiography with thermal neutrons is straightforward and efficient as thermal neutrons are easier to detect with relatively higher efficiency and can be easily extracted from nuclear reactor beam ports. The quality of images obtained using neutron radiography and the imaging speed depend on the neutron beam intensity at the imaging plane. A high quality neutron beam, with thermal neutron intensity greater than 3.0x 10 6 n/cm2-s and a collimation ratio greater than 100 at the imaging plane, is required for effective dynamic neutron radiography up to 2000 frames per second. The primary objectives of this work are: (1) to optimize a neutron radiography facility for dynamic neutron radiography applications and (2) to investigate a new technique for three-dimensional neutron radiography using information obtained from neutron scattering. In this work, neutron transport analysis and experimental validation of a dynamic neutron radiography facility is studied with consideration of real-time and high-speed neutron radiography requirements. A beam port based dynamic neutron radiography facility, for a target thermal neutron flux of 1.0x107 n/cm2-s, has been analyzed, constructed and experimentally verified at the McMaster Nuclear Reactor. The neutron source strength at the beam tube entrance is evaluated experimentally by measuring the thermal and fast neutron fluxes using copper activation flux-mapping technique. The development of different facility components, such as beam tube liner, gamma ray filter, beam shutter and biological shield, is achieved analytically using neutron attenuation and divergence theories. Monte
Mumot, Marta; Agapov, Alexey
2007-11-26
We have developed a new delivering system for hadron therapy which uses a multileaf collimator and a range shifter. We simulate our delivering beam system with the multi-particle transport code 'Fluka'. From these simulations we obtained information about the dose distributions, about stars generated in the delivering system elements and also information about the neutron flux. All the informations obtained were analyzed from the point of view of radiation protection, homogeneity of beam delivery to patient body, and also in order to improve some modifiers used.
High-intensity ion sources for accelerators with emphasis on H-beam formation and transport
Keller, Roderich
2009-01-01
This paper lays out the fundamental working principles of a variety of high-current ion sources for accelerators in a tutorial manner, and gives examples of specific source types such as d. c. discharge- and rf-driven multicusp sources. Penning-type and ECR-based sources while discussing those principles, pointing out general performance limits as well as the performance parameters of specific sources. Laser-based, two-chamber-. and surface-ionization sources are briefly mentioned. Main aspects of this review are particle feed. ionization mechanism, beam formation and beam transport. Issues seen with beam formation and low-energy transport of negative hydrogen-ion beams are treated in detail.
TRANSPORT OF WASTE SIMULANTS IN PJM VENT LINES
Qureshi, Z
2007-02-21
The experimental work was conducted to determine whether there is a potential for waste simulant to transport or 'creep' up the air link line and contaminate the pulse jet vent system, and possibly cause long term restriction of the air link line. Additionally, if simulant creep occurred, establish operating parameters for washing down the line. The amount of the addition of flush fluids and mixer downtime must be quantified.
NASA Astrophysics Data System (ADS)
Jarry, G.; Graham, S. A.; Jaffray, D. A.; Moseley, D. J.; Verhaegen, F.
2006-03-01
In this work Monte Carlo (MC) simulations are used to correct kilovoltage (kV) cone-beam computed tomographic (CBCT) projections for scatter radiation. All images were acquired using a kV CBCT bench-top system composed of an x-ray tube, a rotation stage and a flat-panel imager. The EGSnrc MC code was used to model the system. BEAMnrc was used to model the x-ray tube while a modified version of the DOSXYZnrc program was used to transport the particles through various phantoms and score phase space files with identified scattered and primary particles. An analytical program was used to read the phase space files and produce image files. The scatter correction was implemented by subtracting Monte Carlo predicted scatter distribution from measured projection images; these projection images were then reconstructed. Corrected reconstructions showed an important improvement in image quality. Several approaches to reduce the simulation time were tested. To reduce the number of simulated scatter projections, the effect of varying the projection angle on the scatter distribution was evaluated for different geometries. It was found that the scatter distribution does not vary significantly over a 30-degree interval for the geometries tested. It was also established that increasing the size of the voxels in the voxelized phantom does not affect the scatter distribution but reduces the simulation time. Different techniques to smooth the scatter distribution were also investigated.
Progress in Simulating Turbulent Electron Thermal Transport in NSTX
Guttenfelder, Walter; Kaye, S. M.; Ren, Y.; Bell, R. E.; Hammett, G. W.; LeBlanc, B. P.; Mikkelsen, D. R.; Peterson, J. L.; Nevins, W. M.; Candy, J.; Yuh, H.
2013-07-17
Nonlinear simulations based on multiple NSTX discharge scenarios have progressed to help differentiate unique instability mechanisms and to validate with experimental turbulence and transport data. First nonlinear gyrokinetic simulations of microtearing (MT) turbulence in a high-beta NSTX H-mode discharge predict experimental levels of electron thermal transport that are dominated by magnetic flutter and increase with collisionality, roughly consistent with energy confinement times in dimensionless collisionality scaling experiments. Electron temperature gradient (ETG) simulations predict significant electron thermal transport in some low and high beta discharges when ion scales are suppressed by E x B shear. Although the predicted transport in H-modes is insensitive to variation in collisionality (inconsistent with confinement scaling), it is sensitive to variations in other parameters, particularly density gradient stabilization. In reversed shear (RS) Lmode discharges that exhibit electron internal transport barriers, ETG transport has also been shown to be suppressed nonlinearly by strong negative magnetic shear, s<<0. In many high beta plasmas, instabilities which exhibit a stiff beta dependence characteristic of kinetic ballooning modes (KBM) are sometimes found in the core region. However, they do not have a distinct finite beta threshold, instead transitioning gradually to a trapped electron mode (TEM) as beta is reduced to zero. Nonlinear simulations of this "hybrid" TEM/KBM predict significant transport in all channels, with substantial contributions from compressional magnetic perturbations. As multiple instabilities are often unstable simultaneously in the same plasma discharge, even on the same flux surface, unique parametric dependencies are discussed which may be useful for distinguishing the different mechanisms experimentally.
Intense heavy-ion beam transport with electric and magnetic quadrupoles
Fessenden, T.J.; Barnard, J.J.; Cable, M.D.; Deadrick, F.J.; Eylon, S.; Nelson, M.B.; Sangster, T.C.; Hopkins, H.S.
1995-08-01
As part of the small induction recirculator development at LLNL, the authors are testing an injector and transport line that delivers 4 {micro}s beams of potassium with repetition rates up to 10 Hz at a nominal current of 2 mA. The normalized K-V equivalent emittance of the beams is near 0.02 {pi} mm-mrad and is mostly determined by the temperature of the source (0.1 eV). K{sup +} ions generated at 80 keV in a Pierce diode are matched to an alternating gradient transport line by seven electric quadrupoles. Two additional quads have been modified to serve as two-axis steerers. The matching section is followed by a transport section comprised of seven permanent magnet quadrupoles. Matching to this section is achieved by adjusting the voltages on the electric quadrupoles to voltages calculated by an envelope matching code. Measurements of beam envelope parameters are made at the matching section entrance and exit as well as at the end of the permanent magnet transport section. Beam current waveforms along the experiment are compared with results from a one-dimension longitudinal dynamics code. Initial experiments show particle loss occurring at the beam head as a result of overtaking. The apparatus is also being used for the development of non or minimally intercepting diagnostics for future recirculator experiments. These include capacitive monitors for determining beam line-charge density and position in the recirculator; flying wire scanners for beam position; and gated TV scanners for measuring beam profiles and emittance.
Surface processing with ionized cluster beams: computer simulation
NASA Astrophysics Data System (ADS)
Insepov, Z.; Yamada, I.
1999-06-01
Molecular Dynamics (MD) and Monte Carlo (MC) models of energetic gas cluster irradiation of a solid surface have been developed to investigate the phenomena of crater formation, sputtering, surface treatment, and the material hardness evaluation by irradiation with cluster ions. Theoretical estimation of crater dimensions formed with Ar gas cluster ion irradiation of different substrates, based on hydrodynamics and MD simulation, are presented. The atomic scale shock waves arising from cluster impact were obtained by calculating the pressure, temperature and mass-velocity of the target atoms. The crater depth is given as a unique 1/3 dependence on the cluster energy and on the cold material Brinell hardness number (BHN). A new "true material hardness" scale which can be very useful for example for thin film coatings deposited on a soft substrate, is defined. This finding could be used as a new technique for measuring of a material hardness. Evolution of surface morphology under cluster ion irradiation was described by the surface relaxation equation which contains a term of crater formation at cluster impact. The formation of ripples on a surface irradiated with oblique cluster ion beams was predicted. MD and MC models of Decaborane ion (B 10H 14) implantation into Si and the following rapid thermal annealing (RTA) have been developed.
Range and Energy Straggling in Ion Beam Transport
NASA Technical Reports Server (NTRS)
Wilson, John W.; Tai, Hsiang
2000-01-01
A first-order approximation to the range and energy straggling of ion beams is given as a normal distribution for which the standard deviation is estimated from the fluctuations in energy loss events. The standard deviation is calculated by assuming scattering from free electrons with a long range cutoff parameter that depends on the mean excitation energy of the medium. The present formalism is derived by extrapolating Payne's formalism to low energy by systematic energy scaling and to greater depths of penetration by a second-order perturbation. Limited comparisons are made with experimental data.
Optimized Superconducting Quadrupole Arrays for Multiple Beam Transport
Meinke, Rainer, B.; Goodzeit, Carl, L.; Ball, Millicent, J.
2005-09-20
This research project advanced the development of reliable, cost-effective arrays of superconducting quadrupole magnets for use in multi-beam inertial fusion accelerators. The field in each array cell must be identical and meet stringent requirements for field quality and strength. An optimized compact array design using flat double-layer pancake coils was developed. Analytical studies of edge termination methods showed that it is feasible to meet the requirements for field uniformity in all cells and elimination of stray external field in several ways: active methods that involve placement of field compensating coils on the periphery of the array or a passive method that involves use of iron shielding.
Space-charge limits on the transport of ion beams in a long alternating gradient system
Tiefenback, M.G.
1986-11-01
We have experimentally studied the space-charge-dominated transport of ion beams in an alternating-gradient channel, without acceleration. We parameterize the focusing strength in terms of the zero-current ''betatron'' oscillation phase advance rate, sigma/sub 0/ (degrees per focusing period). We have investigated the conditions for ''stability'', defined as the constancy of the total current and phase space area of the beam during transport. We find that the beam may be transported with neither loss of current nor growth in phase area if sigma/sub 0/ < 90/sup 0/. In this regime, the space-charge repulsive force can counter 98-99% of the externally applied focusing field, and the oscillation frequency of the beam particles can be depressed by self-forces to almost a factor of 10 below the zero-current value, limited only by the optical quality of our ion source. For sigma/sub 0/ > 90/sup 0/, we find that collective interactions bound the maintainable density of the beam, and we present a simple, semi-empirical characterization for stability, within our ability to distinguish the growth rate from zero in our apparatus. Our channel comprises 87 quadrupole lenses, 5 of which are used to prepare the beam for injection into the non-azimuthally-symmetric focusing channel.
Weak-strong Beam-beam Simulations for HL-LHC
Banfi, Danilo; Barranco, Javier; Pieloni, Tatiana; Valishev, Alexander
2014-07-01
In this paper we present dynamic aperture studies for possible High Luminosity LHC optics in the presence of beam-beam interactions, crab crossing schemes and magnets multipolar errors. Possible operational scenarios of luminosity leveling by transverse offset and betatron function are also studied and the impact on the beams stability is discussed.
Belosi, Maria F.; Fogliata, Antonella E-mail: afc@iosi.ch; Cozzi, Luca; Clivio, Alessandro; Nicolini, Giorgia; Vanetti, Eugenio; Rodriguez, Miguel; Sempau, Josep; Krauss, Harald; Khamphan, Catherine; Fenoglietto, Pascal; Puxeu, Josep; Fedele, David; Mancosu, Pietro; Brualla, Lorenzo
2014-05-15
Purpose: Phase-space files for Monte Carlo simulation of the Varian TrueBeam beams have been made available by Varian. The aim of this study is to evaluate the accuracy of the distributed phase-space files for flattening filter free (FFF) beams, against experimental measurements from ten TrueBeam Linacs. Methods: The phase-space files have been used as input in PRIMO, a recently released Monte Carlo program based on thePENELOPE code. Simulations of 6 and 10 MV FFF were computed in a virtual water phantom for field sizes 3 × 3, 6 × 6, and 10 × 10 cm{sup 2} using 1 × 1 × 1 mm{sup 3} voxels and for 20 × 20 and 40 × 40 cm{sup 2} with 2 × 2 × 2 mm{sup 3} voxels. The particles contained in the initial phase-space files were transported downstream to a plane just above the phantom surface, where a subsequent phase-space file was tallied. Particles were transported downstream this second phase-space file to the water phantom. Experimental data consisted of depth doses and profiles at five different depths acquired at SSD = 100 cm (seven datasets) and SSD = 90 cm (three datasets). Simulations and experimental data were compared in terms of dose difference. Gamma analysis was also performed using 1%, 1 mm and 2%, 2 mm criteria of dose-difference and distance-to-agreement, respectively. Additionally, the parameters characterizing the dose profiles of unflattened beams were evaluated for both measurements and simulations. Results: Analysis of depth dose curves showed that dose differences increased with increasing field size and depth; this effect might be partly motivated due to an underestimation of the primary beam energy used to compute the phase-space files. Average dose differences reached 1% for the largest field size. Lateral profiles presented dose differences well within 1% for fields up to 20 × 20 cm{sup 2}, while the discrepancy increased toward 2% in the 40 × 40 cm{sup 2} cases. Gamma analysis resulted in an agreement of 100% when a 2%, 2 mm criterion
Finite element simulation of food transport through the esophageal body
Yang, Wei; Fung, Tat Ching; Chian, Kerm Sim; Chong, Chuh Khiun
2007-01-01
The peristaltic transport of swallowed material in the esophagus is a neuro-muscular function involving the nerve control, bolus-structure interaction, and structure-mechanics relationship of the tissue. In this study, a finite element model (FEM) was developed to simulate food transport through the esophagus. The FEM consists of three components, i.e., tissue, food bolus and peristaltic wave, as well as the interactions between them. The transport process was simulated as three stages, i.e., the filling of fluid, contraction of circular muscle and traveling of peristaltic wave. It was found that the maximal passive intraluminal pressure due to bolus expansion was in the range of 0.8-10 kPa and it increased with bolus volume and fluid viscosity. It was found that the highest normal and shear stresses were at the inner surface of muscle layer. In addition, the peak pressure required for the fluid flow was predicted to be 1-15 kPa at the bolus tail. The diseases of systemic sclerosis or osteogenesis imperfecta, with the remodeled microstructures and mechanical properties, might induce the malfunction of esophageal transport. In conclusion, the current simulation was demonstrated to be able to capture the main characteristics in the intraluminal pressure and bolus geometry as measured experimentally. Therefore, the finite element model established in this study could be used to further explore the mechanism of esophageal transport in various clinical applications. PMID:17457965
Theory and simulations of electrostatic field error transport
Dubin, Daniel H. E.
2008-07-15
Asymmetries in applied electromagnetic fields cause plasma loss (or compression) in stellarators, tokamaks, and non-neutral plasmas. Here, this transport is studied using idealized simulations that follow guiding centers in given fields, neglecting collective effects on the plasma evolution, but including collisions at rate {nu}. For simplicity the magnetic field is assumed to be uniform; transport is due to asymmetries in applied electrostatic fields. Also, the Fokker-Planck equation describing the particle distribution is solved, and the predicted transport is found to agree with the simulations. Banana, plateau, and fluid regimes are identified and observed in the simulations. When separate trapped particle populations are created by application of an axisymmetric squeeze potential, enhanced transport regimes are observed, scaling as {radical}({nu}) when {nu}<{omega}{sub 0}<{omega}{sub B} and as 1/{nu} when {omega}{sub 0}<{nu}<{omega}{sub B} (where {omega}{sub 0} and {omega}{sub B} are the rotation and axial bounce frequencies, respectively). These regimes are similar to those predicted for neoclassical transport in stellarators.
Koo, Min Ho; Hong, Young Ki; Park, Dong Hyuk; Jo, Seong Gi; Joo, Jinsoo
2011-07-15
A focused electron (E)-beam with various doses was irradiated on the intended positions of conducting polypyrrole (PPy) single nanowire (NW) to fabricate nanojunctions. The current-voltage characteristics and their temperature dependence of the PPy single NW with nanojunctions were measured and analyzed. By increasing the E-beam dose and the number of nanojunctions, the current level of the single NW was dramatically decreased, and the conductance gap became more severe as the temperature decreased. The charge transport behavior varied from three-dimensional variable range hopping to fluctuation induced tunneling models, depending on the dose of focused E-beam. From micro-Raman spectra, the focused E-beam irradiation induced the de-doped states and conformational modification of polymer chains in the nanojunctions. The results suggest that the nanojunctions made by focused E-beam acted as a quasi-potential barrier for charge conduction in the conducting PPy single NW.
Mathematical Simulation of Sediment and Radionuclide Transport in Surface Waters
,
1981-04-01
The study objective of "The Mathematical Simulation of Sediment and Radionuclide Transport in Surface Waters" is to synthesize and test radionuclide transport models capable of realistically assessing radionuclide transport in various types of surface water bodies by including the sediment-radionuclide interactions. These interactions include radionuclide adsorption by sediment; desorption from sediment into water; and transport, deposition, and resuspension of sorbed radionuclides controlled by the sediment movements. During FY-1979, the modification of sediment and contaminant (radionuclide) transport model, FETRA, was completed to make it applicable to coastal waters. The model is an unsteady, two-dimensional (longitudinal and lateral) model that consists of three submodels (for sediment, dissolved-contaminant, and particulate-contaminant transport), coupled to include the sediment-contaminant interactions. In estuaries, flow phenomena and consequent sediment and radionuclide migration are often three-dimensional in nature mainly because of nonuniform channel cross-sections, salinity intrusion, and lateral-flow circulation. Thus, an unsteady, three-dimensional radionuclide transport model for estuaries is also being synthesized by combining and modifying a PNL unsteady hydrothermal model and FETRA. These two radionuclide transport models for coastal waters and estuaries will be applied to actual sites to examine the validity of the codes.
Development of a low-energy beam transport system at KBSI heavy-ion accelerator
NASA Astrophysics Data System (ADS)
Bahng, Jungbae; Lee, Byoung-Seob; Sato, Yoichi; Ok, Jung-Woo; Park, Jin Yong; Yoon, Jang-Hee; Choi, Seyong; Won, Mi-Sook; Kim, Eun-San
2015-01-01
The Korea Basic Science Institute has developed a heavy ion accelerator for fast neutron radiography [1]. To meet the requirements for fast neutron generation, we have developed an accelerator system that consists of an electron cyclotron resonance ion source (ECR-IS), low-energy beam transport (LEBT) system, radio-frequency quadrupole (RFQ), medium-energy beam transport system, and drift tube linac. In this paper, we present the development of the LEBT system as a part of the heavy ion accelerator system, which operates from the ECR-IS to the RFQ entrance.
A Labview based FPGA data acquisition with integrated stage and beam transport control
NASA Astrophysics Data System (ADS)
Laird, J. S.; Szymanski, R.; Ryan, C. G.; Gonzalez-Alvarez, I.
2013-07-01
We report on a new FPGA based data acquisition system developed for the CSIRO Nuclear Microprobe (NMP) which is tightly integrated with both target positioning and beam transport. The data acquisition system called MicrodaQ is based on National Instruments Labview FPGA and numerous instrumentation modules spread over several PC's. Beam transport uses a feedback control loop to optimise current on target for long unmanned experiments. These upgrades are discussed in detail and an example of the systems use for μ-Particle Induced X-ray Emission (PIXE) analysis on a Doriri apatite is briefly described.
Dust transport and abrasion assessment within simulated standing vegetation
Technology Transfer Automated Retrieval System (TEKTRAN)
Crop residues are useful in protecting the top soil from depletion and abrasion due to wind erosion. A wind tunnel study was done to measure sand transport and abrasion energies within the simulated artificial standing vegetation. Wind profiles, relative abrasion energies and rates of sand dischar...
Simulation of fumigant transport and volatilization from tarped broadcast applications
Technology Transfer Automated Retrieval System (TEKTRAN)
We evaluated the ability of the HYDRUS 2D/3D model to simulate chloropicrin and 1,3-dichloropropene fate, transport and volatilization. Three fields with similar soil conditions were broadcast fumigated under a totally impermeable film (TIF). One field was used to calibrate HYDRUS by adjusting fumig...
In-beam production and transport of radioactive {sup 17}F at ATLAS.
Pardo, R. C.
1998-11-30
Beam currents of radioactive {sup 17}F(T{sub 1/2} = 65s) as high as 2 x 10{sup 6} s{sup {minus}1} have been produced at the ATLAS facility and delivered to target for nuclear physics research. The d({sup 16}O, {sup 17}F)n and p({sup 17}O,{sup 17}F)n reaction were used to produce the {sup 17}F in the energy range of 65-110 MeV with {sup 17}F intensities of up to 250 pnA. The target employed is a liquid nitrogen cooled H{sub 2} gas cell, with HAVAR windows, operating at up to 8 x 10{sup 4} Pa pressure. A new beam optics geometry consisting of a superconducting solenoid immediately after the production target followed by a single superconducting resonator has significantly improved the total capture efficiency of the transport system. The superconducting solenoid captures the highly divergent secondary beam and refocuses it to improve the beam match into the remainder of the transport system. A single superconducting resonator then ''debunches'' the beam, reducing the energy spread by a factor of four. The beam energy can also be varied, using the resonant cavity, without changing the primary beam energy. Detailed discussion of the results, comparison to calculations, and further possible improvements will be presented.
Ion beam analysis of rubies and their simulants
NASA Astrophysics Data System (ADS)
Juncomma, U.; Intarasiri, S.; Bootkul, D.; Tippawan, U.
2014-07-01
Ion beam analysis (IBA) is a set of well known powerful analytical techniques which use energetic particle beam as a probe. Among them, two techniques are suitable for gemological analysis, i.e., Particle Induced X-rays Emission (PIXE) and Ionoluminescence (IL). We combine these two techniques for the investigations of rubies and their simulants. The main objective is to find a reference fingerprint of these gemstones. The data are collected from several natural rubies, synthetic rubies, red spinels, almandine garnets and rubellite which very much resemble and are difficult to distinguish with the gemologist loupe. From our measurements, due to their different crystal structures and compositions, can be clearly distinguished by the IL and PIXE techniques. The results show that the PIXE spectra consist of a few dominant lines of the host matrix elements of each gemstone and some weaker lines due to trace elements of transition metals. PIXE can easily differentiate rubies from other stones by evaluating their chemical compositions. It is noticed that synthetic rubies generally contain fewer impurities, lower iron and higher chromium than the natural ones. Moreover, the IL spectrum of ruby is unique and different from those of others stones. The typical spectrum of ruby is centered at 694 nm, with small sidebands that can be ascribed to a Cr3+ emission spectrum which is dominated by an R-line at the extreme red end of the visible part of the electromagnetic spectrum. Although the spectrum of synthetic ruby is centered at the same wavelength, the peak is stronger due to higher concentration of Cr and lower concentration of Fe than for natural rubies. For spinel, the IL spectrum shows strong deformation where the R-line is split due to the presence of MgO. For rubellite, the peak center is shifted to 692 nm which might be caused by the replacement of Mn3+ at the Al3+ site of the host structure. It is noticed that almandine garnet is not luminescent due to the
Monte Carlo simulation of a collimation system for low-energy beamline of ELI-NP Gamma Beam System
NASA Astrophysics Data System (ADS)
Cardarelli, P.; Gambaccini, M.; Marziani, M.; Bagli, E.; Petrillo, V.; Bacci, A.; Curatolo, C.; Drebot, I.; Vaccarezza, C.
2015-07-01
ELI-nuclear physics (NP) Gamma Beam System (GBS) is an intense and monochromatic gamma beam source based on inverse Compton interaction, currently being built in Bucharest, Romania. The gamma beam produced, with energy ranging from 0.2 to 20 MeV, energy bandwidth 0.5% and flux of about 108photons/s, will be devoted to investigate a broad range of applications such as nuclear physics, astrophysics, material science and life sciences. The radiation produced by an inverse Compton interaction is not intrinsically monochromatic. In fact, the energy of the photons produced is related to the emission angle, therefore the energy bandwidth can be modified adjusting the collimation of the gamma beam. In order to define the optimal layout and evaluate the performance of a collimation system for the ELI-NP-GBS low-energy beamline (0.2-3.5 MeV), a detailed Monte Carlo simulation activity has been carried out. The simulation, using Geant4 and MCNPX codes, included the transport of the gamma beam from the interaction point to the experimental area passing through vacuum pipes, vacuum chambers, collimation system and relative shielding. The effectiveness of the collimation system, in obtaining the required energy distribution and avoiding the contamination due to secondary radiation production, was evaluated. Also, the background radiation generated by collimation and the shielding layout have been studied.
MULTIDIMENSIONAL COUPLED PHOTON-ELECTRON TRANSPORT SIMULATIONS USING NEUTRAL PARTICLE SN CODES
Ilas, Dan; Williams, Mark L; Peplow, Douglas E.; Kirk, Bernadette Lugue
2008-01-01
During the past two years a study was underway at ORNL to assess the suitability of the popular SN neutral particle codes ANISN, DORT and TORT for coupled photon-electron calculations specific to external beam therapy of medical physics applications. The CEPXS-BFP code was used to generate the cross sections. The computational tests were performed on phantoms typical of those used in medical physics for external beam therapy, with materials simulated by water at different densities and the comparisons were made against Monte Carlo simulations that served as benchmarks. Although the results for one-dimensional calculations were encouraging, it appeared that the higher dimensional transport codes had fundamental difficulties in handling the electron transport. The results of two-dimensional simulations using the code DORT with an S16 fully symmetric quadrature set agree fairly with the reference Monte Carlo results but not well enough for clinical applications. While the photon fluxes are in better agreement (generally, within less than 5% from the reference), the discrepancy increases, sometimes very significantly, for the electron fluxes. The paper, however, focuses on the results obtained with the three-dimensional code TORT which had convergence difficulties for the electron groups. Numerical instabilities occurred in these groups. These instabilities were more pronounced with the degree of anisotropy of the problem.
SciDAC advances in beam dynamics simulation: from light sources to colliders
Qiang, Ji; Qiang, J.; Borland, M.; Kabel, A.; Li, R.; Ryne, R.; Stern, E.; Wang, Y.; Wasserman, H.; Zhang, Y.
2008-06-16
In this paper, we report on progress that has been made in beam dynamics simulation, from light sources to colliders, during the first year of SciDAC-II accelerator project,"Community Petascale Project for Accelerator Science and Simulation (ComPASS)." Several parallel computational tools for beam dynamics simulation will be described. A number of applications in current and future accelerator facilities, e.g., LCLS, RHIC, Tevatron, LHC, ELIC, are presented.
SciDAC advances in beam dynamics simulation: from light sources to colliders
Qiang, J.; Borland, M.; Kabel, A.; Li, Rui; Ryne, Robert; Stern, E.; Wang, Y.; Wasserman, H.; Zhang, Y.
2008-08-01
In this paper, we report on progress that has been made in beam dynamics simulation, from light sources to colliders, during the first year of the SciDAC-2 accelerator project 'Community Petascale Project for Accelerator Science and Simulation (ComPASS).' Several parallel computational tools for beam dynamics simulation are described. Also presented are number of applications in current and future accelerator facilities (e.g., LCLS, RHIC, Tevatron, LHC, and ELIC).
[Simulation of an instrumental head for 6 MeV electron beam therapy].
Albini, E; Belletti, S; Corrado, F; Galelli, M; Mascaro, L
1990-10-01
Simulation of a therapy head for 6 MeV electron beams. We present the results of a simulation, performed using a Monte Carlo method, of depth dose curves in water for electron beams of initial kinetic energy of 6.4 MeV, generated by a radiotherapy microtron MM22 Scanditronix. The Fortran code in EGS4: comparison is made between simulated curves, obtained using various approximation criteria, and the experimental one. PMID:2251422
Slowing dynamics of a supersonic beam, simulation and experiments
NASA Astrophysics Data System (ADS)
Hamamda, Mehdi; Taillandier-Loize, Thierry; Baudon, Jacques; Dutier, Gabriel; Perales, Francisco; Ducloy, Martial
2015-08-01
In this paper we present numerical and experimental methods aimed to study the evolution in space and time of a slowed supersonic beam. These generic methods are applicable to a variety of beams and decelerating techniques. The present implemented experimental set up is based upon Zeeman slowing of a metastable atom beam. The detection uses a channel-electron multiplier and a delay-line detector allowing time-of-flight analysis and numerical image reconstruction. In particular a depopulation effect at the centre of the beam is evidenced. In view of quantifying the slowing process, Monte Carlo calculations based on rate-equations are detailed.
Large-scale multi-agent transportation simulations
NASA Astrophysics Data System (ADS)
Cetin, Nurhan; Nagel, Kai; Raney, Bryan; Voellmy, Andreas
2002-08-01
It is now possible to microsimulate the traffic of whole metropolitan areas with 10 million travelers or more, "micro" meaning that each traveler is resolved individually as a particle. In contrast to physics or chemistry, these particles have internal intelligence; for example, they know where they are going. This means that a transportation simulation project will have, besides the traffic microsimulation, modules which model this intelligent behavior. The most important modules are for route generation and for demand generation. Demand is generated by each individual in the simulation making a plan of activities such as sleeping, eating, working, shopping, etc. If activities are planned at different locations, they obviously generate demand for transportation. This however is not enough since those plans are influenced by congestion which initially is not known. This is solved via a relaxation method, which means iterating back and forth between the activities/routes generation and the traffic simulation.
Numerical Simulation of the Self-Heating Effect Induced by Electron Beam Plasma in Atmosphere
NASA Astrophysics Data System (ADS)
Deng, Yongfeng; Tan, Chang; Han, Xianwei; Tan, Yonghua
2012-02-01
For exploiting advantages of electron beam air plasma in some unusual applications, a Monte Carlo (MC) model coupled with heat transfer model is established to simulate the characteristics of electron beam air plasma by considering the self-heating effect. Based on the model, the electron beam induced temperature field and the related plasma properties are investigated. The results indicate that a nonuniform temperature field is formed in the electron beam plasma region and the average temperature is of the order of 600 K. Moreover, much larger volume pear-shaped electron beam plasma is produced in hot state rather than in cold state. The beam ranges can, with beam energies of 75 keV and 80 keV, exceed 1.0 m and 1.2 m in air at pressure of 100 torr, respectively. Finally, a well verified formula is obtained for calculating the range of high energy electron beam in atmosphere.
Simulating tracer transport in variably saturated soils and shallow groundwater
NASA Astrophysics Data System (ADS)
Pan, F.; Yakirevich, A.; Guber, A.; Pachepsky, Y. A.; Gish, T. J.; Nicholson, T. J.; Cady, R.
2009-12-01
The objective of this study was to develop a realistic model to simulate the complex processes of flow and tracer transport in variably saturated soils and to compare simulation results with the detailed monitoring observations. The USDA-ARS OPE3 field site was selected for the case study due to availability of the extensive database on geophysical, biophysical, remote sensing, soil water and groundwater monitoring accumulated in past 10 years. High soil spatial heterogeneity and shallow groundwater were encountered at the site. A pulse of KCL solution was applied to the irrigation plot with an area of 13x14m, and then the plot was irrigated twice a day for three months using the tap water. The chloride concentration was measured at three sampling depths of 12 observation wells at 7 m and 14 m distances from the irrigation plot. Two three-dimensional flow and transport models, HYDRUS-3D and TOUGH2 codes, were applied in this study to simulate flow and chloride transport for the tracer experiment. Respectively, these models represent two conceptual approaches for flow and transport: (a) transport through all of the domain (b) preferential transport via a network of well-connected pathways (fractures) that comprise only part of the bulk soil porosity (matrix) at the field scale, assuming mass exchange between fracture and matrix continua. The atmospheric boundary condition was applied at surface of the model domain and no flux boundary was set at the bottom. The spatially variable and temporally constant pressure heads were specified along the lateral boundaries. The trial-and-error calibration based on zonation of the flow and transport domain was reasonably successful. The maximum concentration levels and the 50% concentration arrival times were described satisfactory. However, with HYDRUS3D we could not accurately reproduce the shape of the breakthrough curves, unlike TOUGH2 that better simulated the front and tailing part of observed breakthrough curves. The
EXPERIMENTAL STUDY OF PROTON-BEAM HALO INDUCED BY BEAM MISMATCH IN LEDA.
Wangler, Thomas P.,; Allen, C. K.; Colestock, P. L. ,; Chan, K. D.; Crandall, K. R.; Garnett, R. W.; Gilpatrick, J. D.; Lysenko, W. P.; Qiang, J.; Schneider, J. D.; Sheffield, R. L.; Smith, H. V.; Schulze, M. E.
2001-01-01
We report measurements of transverse beam halo in mismatched proton beams in a 52-quadrupole FODO transport channel following the 6.7-MeV LEDA RFQ. Beam profiles in both transverse planes are measured using beam-profile diagnostic devices that consist of a movable carbon filament for measurement of the dense beam core, and scraper plates for measurement of the halo. The gradients of the first four quadrupoles can be independently adjusted to mismatch the RFQ output beam into the beam-transport channel. The properties of the measured mismatched beam profiles in the transport channel will be compared with predictions from multiparticle beam-dynamics simulations.
Benchmarking of Proton Transport in Super Monte Carlo Simulation Program
NASA Astrophysics Data System (ADS)
Wang, Yongfeng; Li, Gui; Song, Jing; Zheng, Huaqing; Sun, Guangyao; Hao, Lijuan; Wu, Yican
2014-06-01
The Monte Carlo (MC) method has been traditionally applied in nuclear design and analysis due to its capability of dealing with complicated geometries and multi-dimensional physics problems as well as obtaining accurate results. The Super Monte Carlo Simulation Program (SuperMC) is developed by FDS Team in China for fusion, fission, and other nuclear applications. The simulations of radiation transport, isotope burn-up, material activation, radiation dose, and biology damage could be performed using SuperMC. Complicated geometries and the whole physical process of various types of particles in broad energy scale can be well handled. Bi-directional automatic conversion between general CAD models and full-formed input files of SuperMC is supported by MCAM, which is a CAD/image-based automatic modeling program for neutronics and radiation transport simulation. Mixed visualization of dynamical 3D dataset and geometry model is supported by RVIS, which is a nuclear radiation virtual simulation and assessment system. Continuous-energy cross section data from hybrid evaluated nuclear data library HENDL are utilized to support simulation. Neutronic fixed source and critical design parameters calculates for reactors of complex geometry and material distribution based on the transport of neutron and photon have been achieved in our former version of SuperMC. Recently, the proton transport has also been intergrated in SuperMC in the energy region up to 10 GeV. The physical processes considered for proton transport include electromagnetic processes and hadronic processes. The electromagnetic processes include ionization, multiple scattering, bremsstrahlung, and pair production processes. Public evaluated data from HENDL are used in some electromagnetic processes. In hadronic physics, the Bertini intra-nuclear cascade model with exitons, preequilibrium model, nucleus explosion model, fission model, and evaporation model are incorporated to treat the intermediate energy nuclear
NASA Astrophysics Data System (ADS)
Solodov, A. A.; Anderson, K. S.; Betti, R.; Gotcheva, V.; Myatt, J.; Delettrez, J. A.; Skupsky, S.; Theobald, W.; Stoeckl, C.
2009-05-01
A thorough understanding of future integrated fast-ignition experiments combining compression and heating of high-density thermonuclear fuel requires hybrid (fluid+particle) simulations of the implosion and ignition process. Different spatial and temporal scales need to be resolved to model the entire fast-ignition experiment. The two-dimensional (2D) axisymmetric hydrocode DRACO [P. B. Radha et al., Phys. Plasmas 12, 056307 (2005)] and the 2D/three-dimensional hybrid particle-in-cell code LSP [D. R. Welch et al., Nucl. Instrum. Methods Phys. Res. A 464, 134 (2001)] have been integrated to simulate the implosion and heating of direct-drive, fast-ignition fusion targets. DRACO includes the physics required to simulate compression, ignition, and burn of fast-ignition targets. LSP simulates the transport of hot electrons from the place where they are generated to the dense fuel core where their energy is absorbed. The results from integrated simulations of cone-in-shell CD targets designed for fast-ignition experiments on OMEGA [T. R. Boehly et al., Opt. Commun. 133, 495 (1997); C. Stoeckl et al., Fusion Sci. Technol. 49, 367 (2006)] are presented. Target heating and neutron yields are computed. The results from LSP simulations of electron transport in solid-density plastic targets are also presented. They confirm an increase in the electron divergence angle with the laser intensity in the current experiments. The self-generated resistive magnetic field is found to collimate the hot-electron beam and increase the coupling efficiency of hot electrons with the target. Resistive filamentation of the hot-electron beam is also observed.
Anomalous Electron Transport Due to Multiple High Frequency Beam Ion Driven Alfven Eigenmode
Gorelenkov, N. N.; Stutman, D.; Tritz, K.; Boozer, A.; Delgardo-Aparicio, L.; Fredrickson, E.; Kaye, S.; White, R.
2010-07-13
We report on the simulations of recently observed correlations of the core electron transport with the sub-thermal ion cyclotron frequency instabilities in low aspect ratio plasmas of the National Spherical Torus Experiment (NSTX). In order to model the electron transport of the guiding center code ORBIT is employed. A spectrum of test functions of multiple core localized Global shear Alfven Eigenmode (GAE) instabilities based on a previously developed theory and experimental observations is used to examine the electron transport properties. The simulations exhibit thermal electron transport induced by electron drift orbit stochasticity in the presence of multiple core localized GAE.
Design of the low energy beam transport line between CARIBU and the EBIS charge breeder
Perry, A.; Ostroumov, P. N.; Barcikowski, A.; Dickerson, C.; Kondrashev, S. A.; Mustapha, B.; Savard, G.
2015-01-09
An Electron Beam Ion Source Charge Breeder (EBIS-CB) has been developed to breed radioactive beams from the CAlifornium Rare Isotope Breeder Upgrade (CARIBU) facility at ATLAS. The EBIS-CB will replace the existing ECR charge breeder to increase the intensity and improve the purity of reaccelerated radioactive ion beams. The EBIS-CB is in the final stage of off-line commissioning. Currently, we are developing a low energy beam transport (LEBT) system to transfer CARIBU beams to the EBIS-CB. As was originally planned, an RFQ cooler-buncher will precede the EBIS-CB. Recently, it was decided to include a multi-reflection time-of-flight (MR-TOF) mass-spectrometer following the RFQ. MR-TOF is a relatively new technology used to purify beams with a mass-resolving power up to 3×10{sup 5} as was demonstrated in experiments at CERN/ISOLDE. Very high purity singly-charged radioactive ion beams will be injected into the EBIS for charge breeding and due to its inherent properties, the EBIS-CB will maintain the purity of the charge bred beams. Possible contamination of residual gas ions will be greatly suppressed by achieving ultra-high vacuum in the EBIS trap. This paper will present and discuss the design of the LEBT and the overall integration of the EBIS-CB into ATLAS.
Design of the low energy beam transport line between CARIBU and the EBIS charge breeder
NASA Astrophysics Data System (ADS)
Perry, A.; Ostroumov, P. N.; Barcikowski, A.; Dickerson, C.; Kondrashev, S. A.; Mustapha, B.; Savard, G.
2015-01-01
An Electron Beam Ion Source Charge Breeder (EBIS-CB) has been developed to breed radioactive beams from the CAlifornium Rare Isotope Breeder Upgrade (CARIBU) facility at ATLAS. The EBIS-CB will replace the existing ECR charge breeder to increase the intensity and improve the purity of reaccelerated radioactive ion beams. The EBIS-CB is in the final stage of off-line commissioning. Currently, we are developing a low energy beam transport (LEBT) system to transfer CARIBU beams to the EBIS-CB. As was originally planned, an RFQ cooler-buncher will precede the EBIS-CB. Recently, it was decided to include a multi-reflection time-of-flight (MR-TOF) mass-spectrometer following the RFQ. MR-TOF is a relatively new technology used to purify beams with a mass-resolving power up to 3×105 as was demonstrated in experiments at CERN/ISOLDE. Very high purity singly-charged radioactive ion beams will be injected into the EBIS for charge breeding and due to its inherent properties, the EBIS-CB will maintain the purity of the charge bred beams. Possible contamination of residual gas ions will be greatly suppressed by achieving ultra-high vacuum in the EBIS trap. This paper will present and discuss the design of the LEBT and the overall integration of the EBIS-CB into ATLAS.
Oxygen transport properties estimation by classical trajectory-direct simulation Monte Carlo
NASA Astrophysics Data System (ADS)
Bruno, Domenico; Frezzotti, Aldo; Ghiroldi, Gian Pietro
2015-05-01
Coupling direct simulation Monte Carlo (DSMC) simulations with classical trajectory calculations is a powerful tool to improve predictive capabilities of computational dilute gas dynamics. The considerable increase in computational effort outlined in early applications of the method can be compensated by running simulations on massively parallel computers. In particular, Graphics Processing Unit acceleration has been found quite effective in reducing computing time of classical trajectory (CT)-DSMC simulations. The aim of the present work is to study dilute molecular oxygen flows by modeling binary collisions, in the rigid rotor approximation, through an accurate Potential Energy Surface (PES), obtained by molecular beams scattering. The PES accuracy is assessed by calculating molecular oxygen transport properties by different equilibrium and non-equilibrium CT-DSMC based simulations that provide close values of the transport properties. Comparisons with available experimental data are presented and discussed in the temperature range 300-900 K, where vibrational degrees of freedom are expected to play a limited (but not always negligible) role.
Oxygen transport properties estimation by classical trajectory–direct simulation Monte Carlo
Bruno, Domenico; Frezzotti, Aldo Ghiroldi, Gian Pietro
2015-05-15
Coupling direct simulation Monte Carlo (DSMC) simulations with classical trajectory calculations is a powerful tool to improve predictive capabilities of computational dilute gas dynamics. The considerable increase in computational effort outlined in early applications of the method can be compensated by running simulations on massively parallel computers. In particular, Graphics Processing Unit acceleration has been found quite effective in reducing computing time of classical trajectory (CT)-DSMC simulations. The aim of the present work is to study dilute molecular oxygen flows by modeling binary collisions, in the rigid rotor approximation, through an accurate Potential Energy Surface (PES), obtained by molecular beams scattering. The PES accuracy is assessed by calculating molecular oxygen transport properties by different equilibrium and non-equilibrium CT-DSMC based simulations that provide close values of the transport properties. Comparisons with available experimental data are presented and discussed in the temperature range 300–900 K, where vibrational degrees of freedom are expected to play a limited (but not always negligible) role.
Tahir, N. A.; Arnold, R. C.
1989-07-01
In this paper detailed simulations are presented of radiation-hydrodynamicresponse of gaseous cylindrical targets irradiated with heavy-ion beams thatwill be produced at the Gesellschaft f/umlt u/r Schwerionenforschung, Darmstadt,using a heavy-ion synchrotron (SIS) (/ital Heavy/ /ital Ion//usion/, AIP Conference Proceedings No. 152 (AIP, NewYork, 1986), p. 23). The purpose of this work is to explore material conditionsfor which the thermal radiation effects can be maximized. This is desirable inorder to study a number of interesting and important effects includingmaximization of conversion efficiency of the ion beam energy to thermalradiation and measurement of the target opacity in the SIS experiments. It isexpected that the SIS beams will produce a specific deposition power of 10 TW/g.The simulations in this paper show that a temperature of the order of 10 eVcould be achieved by the SIS beams using homogeneous, cylindrical Xe targets. Ithas been shown that with the help of these computer simulations one should beable to measure the target opacity in these experiments within a factor of 3.Also these calculations show that in the SIS experiments one should be able tohave a 50% conversion efficiency using a Xe target under optimum conditions. Ithas been found that the radiation effects will be optimized in the SISexperiments if the initial target density is of the order of 10/sup /minus/3/ g/cm/sup 3/.If the initial density is too high (of the order of 10/sup /minus/1/ g/cm/sup 3/ or more),hydrodynamic effects will dominate, while, on the other hand, if the initialdensity is too low (of the order of 10/sup /minus/4/ g/cm/sup 3/ or less), the electronthermal conductivity will take over.
NASA Astrophysics Data System (ADS)
Souza, Everton G.; Endler, Antonio; Rizzato, Felipe B.; Pakter, Renato
2012-08-01
We investigate the role of the temperature in the onset of singularities and the consequent breakdown in a macroscopic fluid model for long-range interacting systems. In particular, we consider an adiabatic fluid description for the transport of intense inhomogeneous charged particle beams. We find that there exists a critical temperature below which the fluid model always develops a singularity and breaks down as the system evolves. As the critical temperature is approached, however, the time for the occurrence of the singularity diverges. Therefore, the critical temperature separates two distinct dynamical phases: a nonadiabatic transport at lower temperatures and a completely adiabatic evolution at higher temperatures. These findings are verified with the aid of self-consistent N-particle simulations.
NASA Astrophysics Data System (ADS)
McKenna, P.; MacLellan, D. A.; Butler, N. M. H.; Dance, R. J.; Gray, R. J.; Robinson, A. P. L.; Neely, D.; Desjarlais, M. P.
2015-06-01
The role of low-temperature electrical resistivity in defining the transport properties of mega-Ampere currents of fast (MeV) electrons in solids is investigated using 3D hybrid particle-in-cell (PIC) simulations. By considering resistivity profiles intermediate to the ordered (lattice) and disordered forms of two example materials, lithium and silicon, it is shown that both the magnitude of the resistivity and the shape of the resistivity-temperature profile at low temperatures strongly affect the self-generated resistive magnetic fields and the onset of resistive instabilities, and thus the overall fast electron beam transport pattern. The scaling of these effects to the giga-Ampere electron currents required for the fast ignition scheme for inertial fusion is also explored.
System for transporting an electron beam to the atmosphere for a gun with a plasma emitter
NASA Astrophysics Data System (ADS)
Kornilov, S. Yu.; Rempe, N. G.; Shidlovskiy, S. V.
2016-06-01
We report on the results of simulation of the gas flow in a gun with a plasma emitter and in the system for extracting the electron beam to the atmosphere, constructed on the basis of standard gasdynamic windows (GDWs). The design of the gun and GDWs is described. Calculations are performed for a pressure of about 10-3 Torr in the electron beam generation range. It is shown that the pressure drop to the atmospheric pressure in the system of electron beam extraction to the atmosphere can be ensured by two GDW stages evacuated by pumps with optimal performance.
Framework Application for Core Edge Transport Simulation (FACETS)
Krasheninnikov, Sergei; Pigarov, Alexander
2011-10-15
The FACETS (Framework Application for Core-Edge Transport Simulations) project of Scientific Discovery through Advanced Computing (SciDAC) Program was aimed at providing a high-fidelity whole-tokamak modeling for the U.S. magnetic fusion energy program and ITER through coupling separate components for each of the core region, edge region, and wall, with realistic plasma particles and power sources and turbulent transport simulation. The project also aimed at developing advanced numerical algorithms, efficient implicit coupling methods, and software tools utilizing the leadership class computing facilities under Advanced Scientific Computing Research (ASCR). The FACETS project was conducted by a multi-discipline, multi-institutional teams, the Lead PI was J.R. Cary (Tech-X Corp.). In the FACETS project, the Applied Plasma Theory Group at the MAE Department of UCSD developed the Wall and Plasma-Surface Interaction (WALLPSI) module, performed its validation against experimental data, and integrated it into the developed framework. WALLPSI is a one-dimensional, coarse grained, reaction/advection/diffusion code applied to each material boundary cell in the common modeling domain for a tokamak. It incorporates an advanced model for plasma particle transport and retention in the solid matter of plasma facing components, simulation of plasma heat power load handling, calculation of erosion/deposition, and simulation of synergistic effects in strong plasma-wall coupling.
RCM simulation of interchange transport in Saturn's inner magnetosphere
NASA Astrophysics Data System (ADS)
Hill, T. W.; Liu, X.; Sazykin, S. Y.; Wolf, R.
2013-12-01
Numerical simulations with the Rice Convection Model have been used to study the radial transport of plasma in Saturn's inner magnetosphere (L < 12) where the magnetic field is dominated by the planetary dipole. This transport occurs through a time-variable pattern of wider outflow channels containing cool, dense plasma from interior sources, alternating with narrower inflow channels containing hot, tenuous plasma from the outer magnetosphere. The 'smoking gun' of this interchange transport process is the pervasive presence of V-shaped injection/dispersion signatures in linear energy-time spectrograms that are observed by the Cassini Plasma Spectrometer (CAPS) on every pass through the inner magnetosphere. Using observed hot plasma distributions at L~12 as input, we have now successfully simulated these V-shaped signatures. We will show these simulation results and compare them with observed signatures. We will also describe future improvements to the model including relaxing the dipole-field assumption, thus enabling us to simulate local-time asymmetries imposed by the outer magnetosphere and tail.
Simulations of reactive transport and precipitation with smoothed particle hydrodynamics
NASA Astrophysics Data System (ADS)
Tartakovsky, Alexandre M.; Meakin, Paul; Scheibe, Timothy D.; Eichler West, Rogene M.
2007-03-01
A numerical model based on smoothed particle hydrodynamics (SPH) was developed for reactive transport and mineral precipitation in fractured and porous materials. Because of its Lagrangian particle nature, SPH has several advantages for modeling Navier-Stokes flow and reactive transport including: (1) in a Lagrangian framework there is no non-linear term in the momentum conservation equation, so that accurate solutions can be obtained for momentum dominated flows and; (2) complicated physical and chemical processes such as surface growth due to precipitation/dissolution and chemical reactions are easy to implement. In addition, SPH simulations explicitly conserve mass and linear momentum. The SPH solution of the diffusion equation with fixed and moving reactive solid-fluid boundaries was compared with analytical solutions, Lattice Boltzmann [Q. Kang, D. Zhang, P. Lichtner, I. Tsimpanogiannis, Lattice Boltzmann model for crystal growth from supersaturated solution, Geophysical Research Letters, 31 (2004) L21604] simulations and diffusion limited aggregation (DLA) [P. Meakin, Fractals, scaling and far from equilibrium. Cambridge University Press, Cambridge, UK, 1998] model simulations. To illustrate the capabilities of the model, coupled three-dimensional flow, reactive transport and precipitation in a fracture aperture with a complex geometry were simulated.
One dimensional heavy ion beam transport: Energy independent model. M.S. Thesis
NASA Technical Reports Server (NTRS)
Farhat, Hamidullah
1990-01-01
Attempts are made to model the transport problem for heavy ion beams in various targets, employing the current level of understanding of the physics of high-charge and energy (HZE) particle interaction with matter are made. An energy independent transport model, with the most simplified assumptions and proper parameters is presented. The first and essential assumption in this case (energy independent transport) is the high energy characterization of the incident beam. The energy independent equation is solved and application is made to high energy neon (NE-20) and iron (FE-56) beams in water. The numerical solutions is given and compared to a numerical solution to determine the accuracy of the model. The lower limit energy for neon and iron to be high energy beams is calculated due to Barkas and Burger theory by LBLFRG computer program. The calculated values in the density range of interest (50 g/sq cm) of water are: 833.43 MeV/nuc for neon and 1597.68 MeV/nuc for iron. The analytical solutions of the energy independent transport equation gives the flux of different collision terms. The fluxes of individual collision terms are given and the total fluxes are shown in graphs relative to different thicknesses of water. The values for fluxes are calculated by the ANASTP computer code.
Linear delta-f simulations of nonlocal electron heat transport
Brunner, S.; Valeo, E.; Krommes, J.A.
2000-01-27
Nonlocal electron heat transport calculations are carried out by making use of some of the techniques developed previously for extending the delta f method to transport time scale simulations. By considering the relaxation of small amplitude temperature perturbations of a homogeneous Maxwellian background, only the linearized Fokker-Planck equation has to be solved, and direct comparisons can be made with the equivalent, nonlocal hydrodynamic approach. A quasineutrality-conserving algorithm is derived for computing the self-consistent electric fields driving the return currents. In the low-collisionality regime, results illustrate the importance of taking account of nonlocality in both space and time.
Monte Carlo simulations of charge transport in heterogeneous organic semiconductors
NASA Astrophysics Data System (ADS)
Aung, Pyie Phyo; Khanal, Kiran; Luettmer-Strathmann, Jutta
2015-03-01
The efficiency of organic solar cells depends on the morphology and electronic properties of the active layer. Research teams have been experimenting with different conducting materials to achieve more efficient solar panels. In this work, we perform Monte Carlo simulations to study charge transport in heterogeneous materials. We have developed a coarse-grained lattice model of polymeric photovoltaics and use it to generate active layers with ordered and disordered regions. We determine carrier mobilities for a range of conditions to investigate the effect of the morphology on charge transport.
Tentative design of beam focusing for the AHF linac and transport systems
Swain, G.R.
1989-01-01
Proposals for an advanced hadron facility include building afterburner linacs for LAMPF. A first afterburner, Add-on Linac number 1, is proposed to accelerate the beam from 0.8 to 1.6 GeV. The output beam would then be fed to a compressor ring and to another afterburner, Add-on Linac number 2. We make a rough estimate of the transverse focusing strength needed in these linacs, and consider the transport line from the end of the LAMPF 805-MHz linac to the start of Add-on Linac number 1. A rebuncher is needed in this transport line for proper acceptance of the beam into the add-on linac. 2 refs., 4 figs.
Effect of radial plasma transport at the magnetic throat on axial ion beam formation
NASA Astrophysics Data System (ADS)
Zhang, Yunchao; Charles, Christine; Boswell, Rod
2016-08-01
Correlation between radial plasma transport and formation of an axial ion beam has been investigated in a helicon plasma reactor implemented with a convergent-divergent magnetic nozzle. The plasma discharge is sustained under a high magnetic field mode and a low magnetic field mode for which the electron energy probability function, the plasma density, the plasma potential, and the electron temperature are measured at the magnetic throat, and the two field modes show different radial parametric behaviors. Although an axial potential drop occurs in the plasma source for both field modes, an ion beam is only observed in the high field mode while not in the low field mode. The transport of energetic ions is characterized downstream of the plasma source using the delimited ion current and nonlocal ion current. A decay of ion beam strength is also observed in the diffusion chamber.
Advanced simulation of electron heat transport in fusion plasmas
Lin, Zhihong; Xiao, Y.; Klasky, Scott A; Lofstead, J.
2009-01-01
Electron transport in burning plasmas is more important since fusion products first heat electrons. First-principles simulations of electron turbulence are much more challenging due to the multi-scale dynamics of the electron turbulence, and have been made possible by close collaborations between plasma physicists and computational scientists. The GTC simulations of collisionless trapped electron mode (CTEM) turbulence show that the electron heat transport exhibits a gradual transition from Bohm to gyroBohm scaling when the device size is increased. The deviation from the gyroBohm scaling can be induced by large turbulence eddies, turbulence spreading, and non-diffusive transport processes. Analysis of radial correlation function shows that CTEM turbulence eddies are predominantly microscopic but with a significant tail in the mesoscale. A comprehensive analysis of kinetic and fluid time scales shows that zonal flow shearing is the dominant decorrelation mechanism. The mesoscale eddies result from a dynamical process of linear streamers breaking by zonal flows and merging of microscopic eddies. The radial profile of the electron heat conductivity only follows the profile of fluctuation intensity on a global scale, whereas the ion transport tracks more sensitively the local fluctuation intensity. This suggests the existence of a nondiffusive component in the electron heat flux, which arises from the ballistic radial E x B drift of trapped electrons due to a combination of the presence of mesoscale eddies and the weak de-tuning of the toroidal precessional resonance that drives the CTEM instability. On the other hand, the ion radial excursion is not affected by the mesoscale eddies due to a parallel decorrelation, which is not operational for the trapped electrons because of a bounce averaging process associated with the electron fast motion along magnetic field lines. The presence of the nondiffusive component raises question on the applicability of the usual
Advanced Simulation of Electron Heat Transport in Fusion Plasmas
Lin, Z.; Xiao, Y.; Holod, I.; Zhang, W. L.; Deng, Wenjun; Klasky, Scott A; Lofstead, J.; Kamath, Chandrika; Wichmann, Nathan
2009-01-01
Electron transport in burning plasmas is more important since fusion products first heat electrons. First-principles simulations of electron turbulence are much more challenging due to the multi-scale dynamics of the electron turbulence, and have been made possible by close collaborations between plasma physicists and computational scientists. The GTC simulations of collisionless trapped electron mode (CTEM) turbulence show that the electron heat transport exhibits a gradual transition from Bohm to gyroBohm scaling when the device size is increased. The deviation from the gyroBohm scaling can be induced by large turbulence eddies, turbulence spreading, and non-diffusive transport processes. Analysis of radial correlation function shows that CTEM turbulence eddies are predominantly microscopic but with a significant tail in the mesoscale. A comprehensive analysis of kinetic and fluid time scales shows that zonal flow shearing is the dominant decorrelation mechanism. The mesoscale eddies result from a dynamical process of linear streamers breaking by zonal flows and merging of microscopic eddies. The radial profile of the electron heat conductivity only follows the profile of fluctuation intensity on a global scale, whereas the ion transport tracks more sensitively the local fluctuation intensity. This suggests the existence of a nondiffusive component in the electron heat flux, which arises from the ballistic radial E x B drift of trapped electrons due to a combination of the presence of mesoscale eddies and the weak de-tuning of the toroidal precessional resonance that drives the CTEM instability. On the other hand, the ion radial excursion is not affected by the mesoscale eddies due to a parallel decorrelation, which is not operational for the trapped electrons because of a bounce averaging process associated with the electron fast motion along magnetic field lines. The presence of the nondiffusive component raises question on the applicability of the usual
NASA Astrophysics Data System (ADS)
Artyomov, K. P.; Ryzhov, V. V.; Naumenko, G. A.; Shevelev, M. V.
2012-05-01
Different types of polarization radiation generated by a relativistic electron beam are simulated using fully electromagnetic particle-in-cell (PIC) code KARAT. The simulation results for diffraction radiation, transition radiation, Smith-Purcell radiation and Vavilov-Cherenkov radiation are in a good agreement with experimental data and analytical models. Modern PIC simulation is a good tool to check and predict experimental results.
Marine litter ensemble transport simulations in the southern North Sea.
Neumann, Daniel; Callies, Ulrich; Matthies, Michael
2014-09-15
The drift of marine litter in the southern North Sea was simulated with the offline Lagrangian transport model PELETS-2D. Assuming different source regions, passive tracer particles were released every 28 h within a nine-year period. Based on pre-calculated hourly wind and ocean current data, drift simulations were carried out forward and backward in time with and without the assumption of extra wind forces influencing particle movement. Due to strong variability of currents, backward simulations did not allow for the identification of particular source regions influencing given monitoring sites. Neither accumulation regions at open sea could be identified by forward simulations. A seasonal signal, however, could be identified in the number of tracer particles that reached the coastal areas. Both particle drift velocity and variability of drift paths further increased when an extra wind drift was assumed. PMID:25125287
Comparison of the analytical and simulation results of the equilibrium beam profile
Liu, Z. J.; Zhu Shaoping; Cao, L. H.; Zheng, C. Y.
2007-10-15
The evolution of high current electron beams in dense plasmas has been investigated by using two-dimensional particle-in-cell (PIC) simulations with immobile ions. It is shown that electron beams are split into many filaments at the beginning due to the Weibel instability, and then different filamentation beams attract each other and coalesce. The profile of the filaments can be described by formulas. Hammer et al. [Phys. Fluids 13, 1831 (1970)] developed a self-consistent relativistic electron beam model that allows the propagation of relativistic electron fluxes in excess of the Alfven-Lawson critical-current limit for a fully neutralized beam. The equilibrium solution has been observed in the simulation results, but the electron distribution function assumed by Hammer et al. is different from the simulation results.
3-D Simulations of Plasma Wakefield Acceleration with Non-Idealized Plasmas and Beams
Deng, S.; Katsouleas, T.; Lee, S.; Muggli, P.; Mori, W.B.; Hemker, R.; Ren, C.; Huang, C.; Dodd, E.; Blue, B.E.; Clayton, C.E.; Joshi, C.; Wang, S.; Decker, F.J.; Hogan, M.J.; Iverson, R.H.; O'Connell, C.; Raimondi, P.; Walz, D.; /SLAC
2005-09-27
3-D Particle-in-cell OSIRIS simulations of the current E-162 Plasma Wakefield Accelerator Experiment are presented in which a number of non-ideal conditions are modeled simultaneously. These include tilts on the beam in both planes, asymmetric beam emittance, beam energy spread and plasma inhomogeneities both longitudinally and transverse to the beam axis. The relative importance of the non-ideal conditions is discussed and a worst case estimate of the effect of these on energy gain is obtained. The simulation output is then propagated through the downstream optics, drift spaces and apertures leading to the experimental diagnostics to provide insight into the differences between actual beam conditions and what is measured. The work represents a milestone in the level of detail of simulation comparisons to plasma experiments.
Simulation of contaminated sediment transport in White Oak Creek basin
Bao, Y.; Clapp, R.B.; Brenkert, A.L.; Moore, T.D.; Fontaine, T.A.
1995-12-31
This paper presents a systematic approach to management of the contaminated sediments in the White Oak Creek watershed at Oak Ridge National Laboratory near Oak Ridge, Tennessee. The primary contaminant of concern is radioactive cesium-137 ({sup 137}Cs), which binds to soil and sediment particles. The key components in the approach include an intensive sampling and monitoring system for flood events; modeling of hydrological processes, sediment transport, and contaminant flux movement; and a decision framework with a detailed human health risk analysis. Emphasis is placed on modeling of watershed rainfall-runoff and contaminated sediment transport during flooding periods using the Hydrologic Simulation Program- Fortran (HSPF) model. Because a large number of parameters are required in HSPF modeling, the major effort in the modeling process is the calibration of model parameters to make simulation results and measured values agree as closely as possible. An optimization model incorporating the concepts of an expert system was developed to improve calibration results and efficiency. Over a five-year simulation period, the simulated flows match the observed values well. Simulated total amount of sediment loads at various locations during storms match with the observed values within a factor of 1.5. Simulated annual releases of {sup 137}Cs off-site locations match the data within a factor of 2 for the five-year period. The comprehensive modeling approach can provide a valuable tool for decision makers to quantitatively analyze sediment erosion, deposition, and transport; exposure risk related to radionuclides in contaminated sediment; and various management strategies.
Chiping Chen
2006-10-26
Under the auspices of the research grant, the Intense Beam Theoretical Research Goup at Massachusetts Institute of Technology's Plasma Science and Fusion Center made significant contributions in a number of important areas in the HIF and HEDP research, including: (a) Derivation of rms envelope equations and study of rms envelope dynamics for high-intensity heavy ion beams in a small-aperture AG focusing transport systems; (b) Identification of a new mechanism for chaotic particle motion, halo formation, and beam loss in high-intensity heavy ion beams in a small-aperture AG focusing systems; Development of elliptic beam theory; (d) Study of Physics Issues in the Neutralization Transport Experiment (NTX).
Transport of radioactive ion beams and related safety issues: The {sup 132}Sn{sup +} case study
Osswald, F. Bouquerel, E.; Boutin, D.; Dinkov, A.; Sellam, A.
2014-12-15
The transport of intense radioactive ion beam currents requires a careful design in order to limit the beam losses, the contamination and thus the dose rates. Some investigations based on numerical models and calculations have been performed in the framework of the SPIRAL 2 project to evaluate the performance of a low energy beam transport line located between the isotope separation on line (ISOL) production cell and the experiment areas. The paper presents the results of the transverse phase-space analysis, the beam losses assessment, the resulting contamination, and radioactivity levels. They show that reasonable beam transmission, emittance growth, and dose rates can be achieved considering the current standards.
Cascaded two-photon spectroscopy of Yb atoms with a transportable effusive atomic beam apparatus.
Song, Minsoo; Yoon, Tai Hyun
2013-02-01
We present a transportable effusive atomic beam apparatus for cascaded two-photon spectroscopy of the dipole-forbidden transition (6s(2)(1)S0↔ 6s7s (1)S0) of Yb atoms. An ohmic-heating effusive oven is designed to have a reservoir volume of 1.6 cm(3) and a high degree of atomic beam collimation angle of 30 mrad. The new atomic beam apparatus allows us to detect the spontaneously cascaded two-photons from the 6s7s(1)S0 state via the intercombination 6s6p(3)P1 state with a high signal-to-noise ratio even at the temperature of 340 °C. This is made possible in our apparatus because of the enhanced atomic beam flux and superior detection solid angle. PMID:23464193
Beam Dynamics Simulation Platform and Studies of Beam Breakup in Dielectric Wakefield Structures
NASA Astrophysics Data System (ADS)
Schoessow, P.; Kanareykin, A.; Jing, C.; Kustov, A.; Altmark, A.; Gai, W.
2010-11-01
A particle-Green's function beam dynamics code (BBU-3000) to study beam breakup effects is incorporated into a parallel computing framework based on the Boinc software environment, and supports both task farming on a heterogeneous cluster and local grid computing. User access to the platform is through a web browser.
Beam Dynamics Simulation Platform and Studies of Beam Breakup in Dielectric Wakefield Structures
Schoessow, P.; Kanareykin, A.; Jing, C.; Kustov, A.; Altmark, A.; Gai, W.
2010-11-04
A particle-Green's function beam dynamics code (BBU-3000) to study beam breakup effects is incorporated into a parallel computing framework based on the Boinc software environment, and supports both task farming on a heterogeneous cluster and local grid computing. User access to the platform is through a web browser.
The X-ray Beam Passage through the Collimator Made of Different Materials: Numerical Simulation
NASA Astrophysics Data System (ADS)
Stuchebrov, S. G.; Miloichikova, I. A.; Danilova, I. B.
2016-01-01
The X-ray beam application grows in the research investigations, in the medical diagnosis and treatment, in the industry. In this paper the theoretical model of the actual pulsed X-ray generator RAP-160-5 beam developed in the program “Computer Laboratory (PCLab)” is shown. The simulation data of the X-ray beam profile and shape collimated by different materials (gypsum, corund-zirconia ceramic, lead) are illustrated.
Three-dimensional simulation analysis of the standing-wave free- electron laser two beam accelerator
Wang, C.; Sessler, A.
1993-01-01
We have modified a two-dimensional relativistic klystron code, developed by Ryne and Yu, to simulate both the standing-wave free- electron laser two-beam accelerator and the relativistic klystron two- beam accelerator. In this paper, the code is used to study a standing-wave free-electron laser with three cavities. The effect of the radius of the electron beam on the RF output power; namely, a three-dimensional effect is examined.
Spherically Symmetric Core Collapse Supernova Simulations With Boltzmann Neutrino Transport
NASA Astrophysics Data System (ADS)
Messer, O. E. B.
2001-12-01
I will describe the results of several spherically symmetric core collapse supernova simulations performed with AGILE-BOLTZTRAN, a state-of-the-art radiation hydrodynamics code incorporating Boltzmann neutrino transport. Collapse simulations comparing two 15 M⊙ progenitor models with significant differences in initial Ye (Woosley & Weaver 1995, Heger et al. 2000) exhibit no differences in Ye at bounce, and, consequently, no difference in homologous core mass and shock formation radius. Fully dynamic simulations of core collapse, rebound, and shock propagation for 15 M⊙ and 20 M⊙ progenitor models of Nomoto & Hashimoto (1988) fail to produce explosions. In both cases, the shock stalls at 200 km, then recedes for several hundred milliseconds. The marked similarities observed in all these simulations highlight the need for both improved progenitor models and the incorporation of improved microphysics in modern supernova codes. Spherically symmetric simulations are, for the immediate future, the only computationally feasible way to investigate the nature of the explosion mechanism while including the requisite level of detailed neutrino transport. They also provide one of the few opportunities to delineate the effects of various feedback mechanisms present in the problem. This research was supported by funds from the Joint Institute for Heavy Ion Research and a DOE PECASE award, and made use of the resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.
Luo, Y.; Fischer, W.
2010-08-01
In this note we summarize the calculated particle loss of a proton bunch in the presence of head-on beam-beam compensation in the Relativistic Heavy Ion Collider (RHIC). To compensate the head-on beam-beam effect in the RHIC 250 GeV polarized proton run, we are introducing a DC electron beam with the same transverse profile as the proton beam to collide with the proton beam. Such a device is called an electron lens (e-lens). In this note we first present the optics and beam parameters and the tracking setup. Then we calculate and compare the particle loss of a proton bunch with head-on beam-beam compensation, phase advance of k{pi} between IP8 and the center of the e-lens and second order chromaticity correction. We scanned the proton beam's linear chromaticity, working point and bunch intensity. We also scanned the electron beam's intensity, transverse beam size. The effect of the electron-proton transverse offset in the e-lens was studied. In the study 6-D weak-strong beam-beam interaction model a la Hirata is used for proton collisions at IP6 and IP8. The e-lens is modeled as 8 slices. Each slice is modeled with as drift - (4D beam-beam kick) - drift.
BEAMR: An interactive graphic computer program for design of charged particle beam transport systems
NASA Technical Reports Server (NTRS)
Leonard, R. F.; Giamati, C. C.
1973-01-01
A computer program for a PDP-15 is presented which calculates, to first order, the characteristics of charged-particle beam as it is transported through a sequence of focusing and bending magnets. The maximum dimensions of the beam envelope normal to the transport system axis are continuously plotted on an oscilloscope as a function of distance along the axis. Provision is made to iterate the calculation by changing the types of magnets, their positions, and their field strengths. The program is especially useful for transport system design studies because of the ease and rapidity of altering parameters from panel switches. A typical calculation for a system with eight elements is completed in less than 10 seconds. An IBM 7094 version containing more-detailed printed output but no oscilloscope display is also presented.
Status of LHC crab activity simulations and beam studies
Calaga,R.; Assman, R.; Barranco, J.; Barranco, J.; Calaga, R.; Caspers, F.; Ciapala, E.; De-Maria, R.; Koutchouk, J. P.; Linnecar, T.; Metral, E.; Morita, A.; Solyak, N.; Sun, Y.; Tomas, R.; Tuckmantel, J.; Weiler, T.; Zimmermann, F.
2009-05-04
The LHC crab cavity program is advancing rapidly towards a first prototype which is anticipated to be tested during the early stages of the LHC phase I upgrade and commissioning. The general project status and some aspects related to crab optics, collimation, aperture constraints, impedances, noise effects. beam transparency and machine protection critical for a safe and robust operation of LHC beams with crab cavities are addressed here.
Electron heat transport from stochastic fields in gyrokinetic simulations
Wang, E.; Nevins, W. M.; Candy, J.; Hatch, D.; Terry, P.; Guttenfelder, W.
2011-05-15
GYRO is used to examine the perturbed magnetic field structure generated by electromagnetic gyrokinetic simulations of the CYCLONE base case as {beta}{sub e} is varied from 0.1% to 0.7%, as investigated by J. Candy [Phys. Plasmas 12, 072307 (2005)]. Poincare surface of section plots obtained from integrating the self-consistent magnetic field demonstrates widespread stochasticity for all nonzero values of {beta}{sub e}. Despite widespread stochasticity of the perturbed magnetic fields, no significant increase in electron transport is observed. The magnetic diffusion, d{sub m}[A. B. Rechester and M. N. Rosenbluth, Phys. Rev. Lett 40, 38 (1978)], is used to quantify the degree of stochasticity and related to the electron heat transport for hundreds of time slices in each simulation.
Thermoelectric transport properties of molybdenum from abinitio simulations
NASA Astrophysics Data System (ADS)
French, Martin; Mattsson, Thomas R.
2014-10-01
We employ abinitio simulations based on density functional theory (DFT) to calculate the electronic transport coefficients (electrical conductivity, thermal conductivity, and thermopower) of molybdenum over a broad range of thermodynamic states. By comparing to available experimental data, we show that DFT is able to describe the desired transport properties of this refractory metal with high accuracy. Most noteworthy, both the positive sign and the quantitative values of the thermopower of solid molybdenum are reproduced very well. We calculate the electrical and thermal conductivity in the solid and the fluid phase between 1000 and 20 000 K and a wide span in density and develop empirical fit formulas for direct use in practical applications, such as magneto-hydrodynamics simulations. The influence of thermal expansion in conductivity measurements at constant pressure is also discussed in some detail.
NASA Astrophysics Data System (ADS)
Comunian, Alessandro; De Micheli, Leonardo; Lazzati, Claudio; Felletti, Fabrizio; Giacobbo, Francesca; Giudici, Mauro; Bersezio, Riccardo
2016-03-01
The fine-scale heterogeneity of porous media affects the large-scale transport of solutes and contaminants in groundwater and it can be reproduced by means of several geostatistical simulation tools. However, including the available geological information in these tools is often cumbersome. A hierarchical simulation procedure based on a binary tree is proposed and tested on two real-world blocks of alluvial sediments, of a few cubic meters volume, that represent small-scale aquifer analogs. The procedure is implemented using the sequential indicator simulation, but it is so general that it can be adapted to various geostatistical simulation tools, improving their capability to incorporate geological information, i.e., the sedimentological and architectural characterization of heterogeneity. When compared with a standard sequential indicator approach on bi-dimensional simulations, in terms of proportions and connectivity indicators, the proposed procedure yields reliable results, closer to the reference observations. Different ensembles of three-dimensional simulations based on different hierarchical sequences are used to perform numerical experiments of conservative solute transport and to obtain ensembles of equivalent pore velocity and dispersion coefficient at the scale length of the blocks (meter). Their statistics are used to estimate the impact of the variability of the transport properties of the simulated blocks on contaminant transport modeled on bigger domains (hectometer). This is investigated with a one-dimensional transport modeling based on the Kolmogorov-Dmitriev theory of branching stochastic processes. Applying the proposed approach with diverse binary trees and different simulation settings provides a great flexibility, which is revealed by the differences in the breakthrough curves.
Kaufmann, Vander; Pinheiro, Adilson; Castro, Nilza Maria dos Reis
2014-05-01
Intense rainfall adversely affects agricultural areas, causing transport of pollutants. Physically-based hydrological models to simulate flows of water and chemical substances can be used to help decision-makers adopt measures which reduce such problems. The purpose of this paper is to evaluate the performance of SWAP and ANIMO models for simulating transport of water, nitrate and phosphorus nutrients, during intense rainfall events generated by a simulator, and during natural rainfall, on a volumetric drainage lysimeter. The models were calibrated and verified using daily time series and simulated rainfall measured at 10-minute intervals. For daily time-intervals, the Nash-Sutcliffe coefficient was 0.865 for the calibration period and 0.805 for verification. Under simulated rainfall, these coefficients were greater than 0.56. The pattern of both nitrate and phosphate concentrations in daily drainage flow under simulated rainfall was acceptably reproduced by the ANIMO model. In the simulated rainfall, loads of nitrate transported in surface runoff varied between 0.08 and 8.46 kg ha(-1), and in drainage form the lysimeter, between 2.44 and 112.57 kg ha(-1). In the case of phosphate, the loads transported in surface runoff varied between 0.002 and 0.504 kg ha(-1), and in drainage, between 0.005 and 1.107 kg ha(-1). The use of the two models SWAP and ANIMO shows the magnitudes of nitrogen and phosphorus fluxes transported by natural and simulated intense rainfall in an agricultural area with different soil management procedures, as required by decision makers. PMID:24650647
Simulation of runaway electrons, transport affected by J-TEXT resonant magnetic perturbation
NASA Astrophysics Data System (ADS)
Jiang, Z. H.; Wang, X. H.; Chen, Z. Y.; Huang, D. W.; Sun, X. F.; Xu, T.; Zhuang, G.
2016-09-01
The topology of a magnetic field and transport properties of runaway electrons can be changed by a resonant magnetic perturbation field. The J-TEXT magnetic topology can be effectively altered via static resonant magnetic perturbation (SRMP) and dynamic resonant magnetic perturbation (DRMP). This paper studies the effect of resonant magnetic perturbation (RMP) on the confinement of runaway electrons via simulating their drift orbits in the magnetic perturbation field and calculating the orbit losses for different runaway initial energies and different runaway electrons, initial locations. The model adopted is based on Hamiltonian guiding center equations for runaway electrons, and the J-TEXT magnetic turbulences and RMP are taken into account. The simulation indicates that the loss rate of runaway electrons is sensitive to the radial position of electrons. The loss of energetic runaway beam is dominated by the shrinkage of the confinement region. Outside the shrinkage region of the runaway electrons are lost rapidly. Inside the shrinkage region the runaway beam is confined very well and is less sensitive to the magnetic perturbation. The experimental result on the response of runaway transport to the application RMP indicates that the loss of runaway electrons is dominated by the shrinkage of the confinement region, other than the external magnetic perturbation.
NASA Astrophysics Data System (ADS)
Miloichikova, I. A.; Stuchebrov, S. G.; Zhaksybayeva, G. K.; Wagner, A. R.
2015-11-01
Nowadays, the commercial application of the electron accelerators grows in the industry, in the research investigations, in the medical diagnosis and treatment. In this regard, the electron beam profile modification in accordance with specific purposes is an actual task. In this paper the model of the TPU microtron extracted electron beam developed in the program “Computer Laboratory (PCLab)” is described. The internal beam divergence influence for the electron beam profile and depth dose distribution in the air is considered. The possibility of using the nanostructure materials for the electron beam formation was analyzed. The simulation data of the electron beam shape collimated by different materials (lead, corund- zirconia nanoceramic, gypsum) are shown. The collimator material influence for the electron beam profile and shape are analyzed.
Optical simulation of laser beam phase-shaping focusing optimization in biological tissues
NASA Astrophysics Data System (ADS)
Gomes, Ricardo; Vieira, Pedro; Coelho, João. M. P.
2013-11-01
In this paper we report the development of an optical simulator that can be used in the development of methodologies for compensate/decrease the light scattering effect of most biological tissues through phase-shaping methods. In fact, scattering has long been a major limitation for the medical applications of lasers where in-depth tissues concerns due to the turbid nature of most biological media in the human body. In developing the simulator, two different approaches were followed: one using multiple identical beams directed to the same target area and the other using a phase-shaped beam. In the multiple identical beams approach (used mainly to illustrate the limiting effect of scattering on the beam's propagation) there was no improvement in the beam focus at 1 mm compared to a single beam layout but, in phase-shaped beam approach, a 8x improvement on the radius of the beam at the same depth was achieved. The models were created using the optical design software Zemax and numerical algorithms created in Matlab programming language to shape the beam wavefront. A dedicated toolbox allowed communication between both programs. The use of the two software's proves to be a simple and powerful solution combining the best of the two and allowing a significant potential for adapting the simulations to new systems and thus allow to assess their response and define critical engineering parameters prior to laboratorial implementation.
Long Baseline Neutrino Experiment simulation studies on Offset of Detector and Proton Beam
NASA Astrophysics Data System (ADS)
Bashyal, Amit; Yu, Jaehoon; Park, Seongtae; Watson, Blake
2014-03-01
The Long Baseline Neutrino Experiment(LBNE), hosted by Fermilab is a world class physics program aiming to probe our understanding on neutrino physics and look for physics beyond Standard Model. While LBNE is still under development, the LBNE beam simulation group performs the simulation using the G4LBNE simulation software and packaged geometry. The simulation studies are done by shifting and offsetting several parameters (which represent the physical components of the real experiment). The results obtained were analyzed graphically and statistically. In this talk, I will explain the effect of beam offset and detector shifting on parameters like pion production in the decay pipe, intensity of neutrino flux, variation on the number of neutrinos in specific energy ranges. Simulation experiment results will help to simplify the complex nature of neutrinos itself to a small extent and the collective work from the beam simulation group can provide a raw guideline for the experiment itself in the long run.
Fluid simulation of relativistic electron beam driven wakefield in a cold plasma
Bera, Ratan Kumar; Sengupta, Sudip; Das, Amita
2015-07-15
Excitation of wakefield in a cold homogeneous plasma, driven by an ultra-relativistic electron beam is studied in one dimension using fluid simulation techniques. For a homogeneous rigid beam having density (n{sub b}) less than or equal to half the plasma density (n{sub 0}), simulation results are found to be in good agreement with the analytical work of Rosenzweig [Phys. Rev. Lett. 58, 555 (1987)]. Here, Rosenzweig's work has been analytically extended to regimes where the ratio of beam density to plasma density is greater than half and results have been verified using simulation. Further in contrast to Rosenzweig's work, if the beam is allowed to evolve in a self-consistent manner, several interesting features are observed in simulation viz. splitting of the beam into beam-lets (for l{sub b} > λ{sub p}) and compression of the beam (for l{sub b} < λ{sub p}), l{sub b} and λ{sub p}, respectively, being the initial beam length and plasma wavelength.
Note on quantitatively correct simulations of the kinetic beam-plasma instability
Lotov, K. V.; Timofeev, I. V.; Mesyats, E. A.; Snytnikov, A. V.; Vshivkov, V. A.
2015-02-15
A large number of model particles are shown necessary for quantitatively correct simulations of the kinetic beam-plasma instability with the clouds-in-cells method. The required number of particles scales inversely with the expected growth rate, as only a narrow interval of beam velocities is resonant with the wave in the kinetic regime.
Simulating and Modeling Transport Through Atomically Thin Membranes
NASA Astrophysics Data System (ADS)
Ostrowski, Joseph; Eaves, Joel
2014-03-01
The world is running out of clean portable water. The efficacy of water desalination technologies using porous materials is a balance between membrane selectivity and solute throughput. These properties are just starting to be understood on the nanoscale, but in the limit of atomically thin membranes it is unclear whether one can apply typical continuous time random walk models. Depending on the size of the pore and thickness of the membrane, mass transport can range from single stochastic passage events to continuous flow describable by the usual hydrodynamic equations. We present a study of mass transport through membranes of various pore geometries using reverse nonequilibrium simulations, and analyze transport rates using stochastic master equations.
Plasma transport in a simulated magnetic-divertor configuration
Strawitch, C. M.
1981-03-01
The transport properties of plasma on magnetic field lines that intersect a conducting plate are studied experimentally in the Wisconsin internal ring D.C. machine. The magnetic geometry is intended to simulate certain aspects of plasma phenomena that may take place in a tokamak divertor. It is found by a variety of measurements that the cross field transport is non-ambipolar; this may have important implications in heat loading considerations in tokamak divertors. The undesirable effects of nonambipolar flow make it preferable to be able to eliminate it. However, we find that though the non-ambipolarity may be reduced, it is difficult to eliminate entirely. The plasma flow velocity parallel to the magnetic field is found to be near the ion acoustic velocity in all cases. The experimental density and electron temperature profiles are compared to the solutions to a one dimensional transport model that is commonly used in divertor theory.
Simulation of Plasma Transport in a Toroidal Annulus with TEMPEST
NASA Astrophysics Data System (ADS)
Xiong, Z.
2005-10-01
TEMPEST is an edge gyro-kinetic continuum code currently under development at LLNL to study boundary plasma transport over a region extending from inside the H-mode pedestal across the separatrix to the divertor plates. Here we report simulation results from the 4D (θ, ψ, E, μ) TEMPEST, for benchmark purpose, in an annulus region immediately inside the separatrix of a large aspect ratio, circular cross-section tokamak. Besides the normal poloidal trapping regions, there are radial inaccessible regions at a fixed poloid angle, energy and magnetic moment due to the radial variation of the B field. To handle such cases, a fifth-order WENO differencing scheme is used in the radial direction. The particle and heat transport coefficients are obtained for different collisional regimes and compared with the neo-classical transport theory.
Solenoid transport of a heavy ion beam for warm dense matterstudies and inertial confinement fusion
Armijo, Julien
2006-10-01
From February to July 2006, I have been doing research as a guest at Lawrence Berkeley National Laboratory (LBNL), in the Heavy Ion Fusion group. This internship, which counts as one semester in my master's program in France, I was very pleased to do it in a field that I consider has the beauty of fundamental physics, and at the same time the special appeal of a quest for a long-term and environmentally-respectful energy source. During my stay at LBNL, I have been involved in three projects, all of them related to Neutralized Drift Compression Experiment (NDCX). The first one, experimental and analytical, has consisted in measuring the effects of the eddy currents induced by the pulsed magnets in the conducting plates of the source and diagnostic chambers of the Solenoid Transport Experiment (STX, which is a subset of NDCX). We have modeled the effect and run finite-element simulations that have reproduced the perturbation to the field. Then, we have modified WARP, the Particle-In-Cell code used to model the whole experiment, in order to import realistic fields including the eddy current effects and some details of each magnet. The second project has been to take part in a campaign of WARP simulations of the same experiment to understand the leakage of electrons that was observed in the experiment as a consequence to some diagnostics and the failure of the electrostatic electron trap. The simulations have shown qualitative agreement with the measured phenomena, but are still in progress. The third project, rather theoretical, has been related to the upcoming target experiment of a thin aluminum foil heated by a beam to the 1-eV range. At the beginning I helped by analyzing simulations of the hydrodynamic expansion and cooling of the heated material. But, progressively, my work turned into making estimates for the nature of the liquid/vapor two-phase flow. In particular, I have been working on criteria and models to predict the formation of droplets, their size, and
Computer simulation of transport driven current in tokamaks
NASA Astrophysics Data System (ADS)
Nunan, W. J.; Dawson, J. M.
1994-09-01
We have investigated transport driven current in tokamaks via 2+1/2 dimensional, electromagnetic, particle-in-cell simulations. These have demonstrated a steady increase of toroidal current in centrally fueled plasmas. Neoclassical theory predicts that the bootstrap current vanishes at large aspect ratio, but we see equal or greater current growth in straight cylindrical plasmas. These results indicate that a centrally fueled and heated tokamak may sustain its toroidal current, even without the ``seed current'' which the neoclassical bootstrap theory requires.