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1

Electrostatic quadrupole focused particle accelerating assembly with laminar flow beam  

DOEpatents

A charged particle accelerating assembly provided with a predetermined ratio of parametric structural characteristics and with related operating voltages applied to each of its linearly spaced focusing and accelerating quadrupoles, thereby to maintain a particle beam traversing the electrostatic fields of the quadrupoles in the assembly in an essentially laminar flow throughout the assembly.

Maschke, Alfred W. (East Moriches, NY)

1985-01-01

2

Electrostatic quadrupole focused particle accelerating assembly with laminar flow beam  

DOEpatents

A charged particle accelerating assembly provided with a predetermined ratio of parametric structural characteristics and with related operating voltages applied to each of its linearly spaced focusing and accelerating quadrupoles, thereby to maintain a particle beam traversing the electrostatic fields of the quadrupoles in the assembly in an essentially laminar flow through the assembly.

Maschke, A.W.

1984-04-16

3

A method for free electron acceleration of particle beams  

SciTech Connect

The large electric fields associated with sources of space charge have led to numerous proposals for possible collective (space-charge-based) accelerators. Traditionally, these schemes involve either magnetic fields or background ions (a plasma) to contain the space charge. This Letter proposes a new technique for particle acceleration that directly uses the large space charge fields of freely moving electron beams. Such free electron accelerators promise eventual accelerating gradients in excess of 10 GV/m.

Larson, D.J. (Superconducting Super Collilder Laboratory, 2550 Beckleymeade Avenue, MS 1040, Dallas, Texas 75237 (United States))

1993-08-09

4

GPU accelerated online multi-particle beam dynamics simulator for ion linear particle accelerators  

NASA Astrophysics Data System (ADS)

An online beam dynamics simulator is being developed for use in the operation of an ion linear particle accelerator. By employing Graphics Processing Unit (GPU) technology, the performance of the simulator has been significantly increased over that of a single CPU and is therefore viable in the demanding accelerator operations environment. Once connected to the accelerator control system, it can rapidly respond to any control set point changes and predict beam properties along an ion linear accelerator in pseudo-real time. This simulator will be a virtual beam diagnostic tool which is especially useful when direct beam measurements are not available. Details about the code structure design, physics algorithms, GPU implementations, and performance are presented.

Pang, X.; Rybarcyk, L.

2014-03-01

5

The Neutral Particle Beam Space Experiment (NPBSE) accelerator designs  

Microsoft Academic Search

Accelerators that are designed to operate in a space environment are more strongly constrained by hardware envelope size, power consumption and cooling requirements than are equivalent ground based systems. The challenges presented by these constraints have resulted in the development of novel features in the Neutral Particle Beam Space Experiment (NPBSE) accelerator designs, which may also find application in ground

C. C. Paulson; A. M. M. Todd; S. L. Mendelsohn

1993-01-01

6

Data handling facility for the Sandia Particle Beam Fusion Accelerator  

SciTech Connect

This paper describes an on-line data handling facility for Sandia's Particle Beam Fusion Accelerator, PBFA-I, and the upgrade prototype machine Supermite. These accelerators are used for research on inertial confinement fusion (ICF) using particle beams. The main objectives in designing the data acquisition system were: (1) process both experiment and machine performance diagnostic signals, (2) record high signal-to-noise ratio, wideband waveforms in a severe EMP environment, (3) support multiple users recording and analyzing data simultaneously, and (4) provide fast turnaround for experimental results. Commercially available equipment is used wherever possible. However, several special purpose devices were developed. This data handling facility is a significant upgrade of an existing system that supports other Sandia particle beam fusion research accelerators.

Boyer, W. B.; Neau, E. L.

1980-01-01

7

Use of Crystals for Beam Deflection in Particle Accelerators  

NASA Astrophysics Data System (ADS)

Charged particles interacting with a bent crystal can be trapped in channeling states and deflected by the atomic planes of the crystal lattice. The use of bent crystals for beam manipulation in particle accelerators is a well assessed concept rapidly evolving into practical applications. In the last three decades, a large number of experimental findings have contributed to clarify our knowledge and to improve our control of crystal-particle interactions. Bent crystals can impart angular deflections to the incoming particles, through channeling or volume reflection mechanisms. The efficiency of the latter mechanism has been found to be intrinsically very large, whilst the channeling efficiency has been improved by the increased technological expertize in crystal cutting and bending. In this paper, we review the recent milestones of the worldwide effort to propose a routine use of bent crystals in particle accelerators, with a specific attention to the proposals of promoting the use of bent crystals as primary element in beam halo collimation systems.

Scandale, Walter

8

Cryogenic cooling tests of a neutral particle beam accelerator component  

Microsoft Academic Search

Due to the need to reduce the power requirements and thus the weight of large space-based neutral particle beam (NPB) space platforms, current systems studies propose that these NPB accelerators be maintained at cryogenic temperature levels. As such, the ground test articles that will be used to develop many of the technological advancements necessary prior to engineering development of an

Stephen J. Black

1988-01-01

9

The propagation distance of the by-product ion beams emitted from neutral particle beam accelerators  

SciTech Connect

The effects of collective electric fields on the propagation of the positive-ion and negative-ion by-products from neutral particle beam accelerators are examined. For present and future space-based neutral particle beam experiments, it is shown that the by-product beams do not propagate across the earth's magnetic field. 4 refs., 3 figs.

Borovsky, J.E.

1989-11-01

10

The propagation distance of the by-product ion beams emitted from neutral particle beam accelerators  

Microsoft Academic Search

The effects of collective electric fields on the propagation of the positive-ion and negative-ion by-products from neutral particle beam accelerators are examined. For present and future space-based neutral particle beam experiments, it is shown that the by-product beams do not propagate across the earth's magnetic field. 4 refs., 3 figs.

Borovsky

1989-01-01

11

Beam-beam simulation code BBSIM for particle accelerators  

NASA Astrophysics Data System (ADS)

A highly efficient, fully parallelized, six-dimensional tracking model for simulating interactions of colliding hadron beams in high energy ring colliders and simulating schemes for mitigating their effects is described. The model uses the weak-strong approximation for calculating the head-on interactions when the test beam has lower intensity than the other beam, a look-up table for the efficient calculation of long-range beam-beam forces, and a self-consistent Poisson solver when both beams have comparable intensities. A performance test of the model in a parallel environment is presented. The code is used to calculate beam emittance and beam loss in the Tevatron at Fermilab and compared with measurements. We also present results from the studies of two schemes proposed to compensate the beam-beam interactions: (a) the compensation of long-range interactions in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven and the Large Hadron Collider (LHC) at CERN with a current-carrying wire, (b) the use of a low-energy electron beam to compensate the head-on interactions in RHIC.

Kim, H. J.; Sen, T.

2011-06-01

12

Beam-beam simulation code BBSIM for particle accelerators  

SciTech Connect

A highly efficient, fully parallelized, six-dimensional tracking model for simulating interactions of colliding hadron beams in high energy ring colliders and simulating schemes for mitigating their effects is described. The model uses the weak-strong approximation for calculating the head-on interactions when the test beam has lower intensity than the other beam, a look-up table for the efficient calculation of long-range beam-beam forces, and a self-consistent Poisson solver when both beams have comparable intensities. A performance test of the model in a parallel environment is presented. The code is used to calculate beam emittance and beam loss in the Tevatron at Fermilab and compared with measurements. They also present results from the studies of stwo schemes proposed to compensate the beam-beam interactions: (a) the compensation of long-range interactions in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven and the Large Hadron Collider (LHC) at CERN with a current carrying wire, (b) the use of a low energy electron beam to compensate the head-on interactions in RHIC.

Kim, Hyung J.; Sen, Tanaji; /Fermilab

2011-01-01

13

Ion beam generation and focusing on PBFA (Particle Beam Fusion Accelerator) II  

Microsoft Academic Search

During the past year we have succeeded in obtaining a 5 TW\\/cm² proton focus on Sandia National Laboratories' Particle Beam Fusion Accelerator (PBFA) II. This has allowed us to shift our experimental emphasis to the implementation of an improved ion diode geometry for higher voltage operation, full azimuthal beam characterization, and especially lithium ion source experiments. We have made significant

R. W. Stinnett; J. E. Bailey; K. W. Bieg; R. S. Coats; G. Chandler; M. S. Derzon; M. P. Desjarlais; P. L. Dreike; R. A. Gerber; D. J. Johnson; R. J. Leeper; T. R. Lockner; J. Maenchen; T. A. Mehlhorn; A. L. Pregenzer; J. P. Quintenz; T. J. Renk; S. E. Rosenthal; C. L. Ruiz; S. A. Slutz; W. A. Stygar; G. C. Tisone; J. R. Woodworth; Y. Maron

1990-01-01

14

Li-beam-heated hohlraum experiments at Particle Beam Fusion Accelerator II  

Microsoft Academic Search

Thermal radiation experiments with 9-MeV Li beams have been performed at Particle Beam Fusion Accelerator II with a peak beam intensity of 1â2TW\\/cm². The peak brightness temperature of the target was 58±4eV. We obtained specific depositions of 800â1600 TW\\/g in the foam. Important features of desired hohlraum performance have been demonstrated. These include a near-Planckian spectrum, increased heating due to

M. S. Derzon; G. A. Chandler; R. J. Dukart; D. J. Johnson; R. J. Leeper; M. K. Matzen; E. J. McGuire; T. A. Mehlhorn; A. R. Moats; R. E. Olson; C. L. Ruiz

1996-01-01

15

Ion beam generation and focusing on PBFA (Particle Beam Fusion Accelerator) II  

SciTech Connect

During the past year we have succeeded in obtaining a 5 TW/cm{sup 2} proton focus on Sandia National Laboratories' Particle Beam Fusion Accelerator (PBFA) II. This has allowed us to shift our experimental emphasis to the implementation of an improved ion diode geometry for higher voltage operation, full azimuthal beam characterization, and especially lithium ion source experiments. We have made significant progress in each of these areas during the past year, demonstrating 10 MV diode operation, {plus minus}10% azimuthal beam symmetry, and promising initial results from lithium ion source experiments. 8 refs., 6 figs.

Stinnett, R.W.; Bailey, J.E.; Bieg, K.W.; Coats, R.S.; Chandler, G.; Derzon, M.S.; Desjarlais, M.P.; Dreike, P.L.; Gerber, R.A.; Johnson, D.J.; Leeper, R.J.; Lockner, T.R.; Maenchen, J.; Mehlhorn, T.A.; Pregenzer, A.L.; Quintenz, J.P.; Renk, T.J.; Rosenthal, S.E.; Ruiz, C.L.; Slutz, S.A.; Stygar, W.A.; Tisone, G.C.; Woodworth, J.R. (Sandia National Labs., Albuquerque, NM (USA)); Maron, Y. (Weizmann Inst. of Science, R

1990-01-01

16

Means and method for the focusing and acceleration of parallel beams of charged particles  

DOEpatents

A novel apparatus and method for focussing beams of charged particles comprising planar arrays of electrostatic quadrupoles. The quadrupole arrays may comprise electrodes which are shared by two or more quadrupoles. Such quadrupole arrays are particularly adapted to providing strong focussing forces for high current, high brightness, beams of charged particles, said beams further comprising a plurality of parallel beams, or beamlets, each such beamlet being focussed by one quadrupole of the array. Such arrays may be incorporated in various devices wherein beams of charged particles are accelerated or transported, such as linear accelerators, klystron tubes, beam transport lines, etc.

Maschke, Alfred W. (East Moriches, NY)

1983-07-05

17

Particle-beam accelerators for radiotherapy and radioisotopes  

SciTech Connect

The philosophy used in developing the new PIGMI technology was that the parameters chosen for physics research machines are not necessarily the right ones for a dedicated therapy or radioisotope machine. In particular, the beam current and energy can be optimized, and the design should emphasize minimum size, simplicity and reliability of operation, and economy in capital and operating costs. A major part of achieving these goals lay in raising the operating frequency and voltage gradient of the accelerator, which shrinks the diameter and length of the components. Several other technical innovations resulted in major system improvements. One of these is a radically new type of accelerator structure named the radio-frequency quadrupole (RFQ) accelerator. This allowed us to eliminate the large, complicated ion source used in previous ion accelerators, and to achieve a very high quality accelerated beam. Also, by using advanced permanent magnet materials to make the focusing elements, the system becomes much simpler. Other improvements have been made in all of the accelerator components and in the methods for operating them. These will be described, and design and costing information examples given for several possible therapy and radioisotope production machines.

Boyd, T.J.; Crandall, K.R.; Hamm, R.W.

1981-01-01

18

On a theory of two-beam mechanisms of charged particle acceleration in electrodynamic structures  

SciTech Connect

This work is devoted to the theoretical studies of two-beam mechanisms of charged particle acceleration in electronic structures. The first section continues the outline of results of theoretical studies commenced in the intermediate report and considers the two-beam scheme of acceleration in the plasma waveguide. According to this scheme the strong current relativistic electron beam (REB) excites the intensive plasma waves accelerating the electrons of the second beam. The driving beam is assumed to be density-modulated. The preliminary modulation of the driving REB is shown to enhance substantially the acceleration efficiency of relativistic electrons of the driven beam. The second section deals with the two-beam acceleration in the vacuum corrugated waveguide. According to this scheme the excitation of electromagnetic waves and acceleration of driven beam electrons by them is accomplished under different Cherenkov resonances between the particles of beams and the corrugated waveguide field. The electromagnetic field in the periodic structure is known to be the superposition of spatial harmonics. With the small depth of the periodic nonuniformity the amplitudes of these harmonics decrease fast with their number increasing. Therefore, if the driving beam is in the Cherenkov resonance with the first spatial harmonic and the driven beam is in resonance with the zero space harmonic then the force accelerating the driven beam would be considerably bigger than the force decelerating the driving beam electrons.

Ostrovsky, A.O. [Kharkov Inst. of Physics and Technology, Kharkov (Ukraine)

1993-09-01

19

Li-beam-heated hohlraum experiments at Particle Beam Fusion Accelerator II  

SciTech Connect

Thermal radiation experiments with 9-MeV Li beams have been performed at Particle Beam Fusion Accelerator II with a peak beam intensity of 1{endash}2TW/cm{sup 2}. The peak brightness temperature of the target was 58{plus_minus}4eV. We obtained specific depositions of 800{endash}1600 TW/g in the foam. Important features of desired hohlraum performance have been demonstrated. These include a near-Planckian spectrum, increased heating due to the presence of a high-{ital Z} wall, x-ray mean free paths greater than the target size between 200 and 280 eV, thermal x-ray emission more uniform than the incident ion energy, and a high-{ital Z} wall velocity less than 3 cm/{mu}s. {copyright} {ital 1996 The American Physical Society.}

Derzon, M.S.; Chandler, G.A.; Dukart, R.J.; Johnson, D.J.; Leeper, R.J.; Matzen, M.K.; McGuire, E.J.; Mehlhorn, T.A.; Moats, A.R.; Olson, R.E.; Ruiz, C.L. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

1996-01-01

20

A theory of two-beam acceleration of charged particles in a plasma waveguide  

SciTech Connect

The progress made in recent years in the field of high-current relativistic electron beam (REB) generation has aroused a considerable interest in studying REB potentialities for charged particle acceleration with a high acceleration rate T = 100MeV/m. It was proposed, in particular, to employ high-current REB in two-beam acceleration schemes (TBA). In these schemes high current REB (driving beam) excites intense electromagnetic waves in the electrodynamic structure which, in their turn, accelerate particles of the other beam (driven beam). The TBA schemes can be divided into two groups. The first group includes the schemes, where the two beams (driving and driven) propagate in different electrodynamic structures coupled with each other through the waveguides which ensure the microwave power transmission to accelerate driven beam particles. The second group includes the TBA schemes, where the driving and driven beams propagate in one electrodynamic structure. The main aim of this work is to demonstrate by theory the possibility of realizing effectively the TBA scheme in the plasma waveguide. The physical model of the TBA scheme under study is formulated. A set of equations describing the excitation of RF fields by a high-current REB and the acceleration of driven beam electrons is also derived. Results are presented on the the linear theory of plasma wave amplification by the driving beam. The range of system parameters, at which the plasma-beam instability develops, is defined. Results of numerical simulation of the TBA scheme under study are also presented. The same section gives the description of the dynamics of accelerated particle bunching in the high-current REB-excited field. Estimates are given for the accelerating field intensities in the plasma and electron acceleration rates.

Ostrovsky, A.O. [Kharkov Inst. of Physics and Technology (Ukraine)

1993-11-01

21

Research and development of superconducting linear accelerators for neutral particle beam applications  

Microsoft Academic Search

Experiments with superconducting cavities designed for applications in continuous-wave, high-current ion linear accelerators have resulted in very high CW accelerating gradients, up to 18 MV\\/m, with only a few watts of power dissipation in the cavity walls. These results make the prospects for compact, lightweight Neutral Particle Beam accelerators very attractive, and they compel further work to develop RF superconductivity

J. R. Delayen; C. L. Bohn; W. L. Kennedy; G. L. Nicholls; C. T. Roche; L. Sagalovsky

1992-01-01

22

Charged particle accelerator grating  

DOEpatents

A readily disposable and replaceable accelerator grating for a relativistic particle accelerator. The grating is formed for a plurality of liquid droplets that are directed in precisely positioned jet streams to periodically dispose rows of droplets along the borders of a predetermined particle beam path. A plurality of lasers are used to direct laser beams into the droplets, at predetermined angles, thereby to excite the droplets to support electromagnetic accelerating resonances on their surfaces. Those resonances operate to accelerate and focus particles moving along the beam path. As the droplets are distorted or destroyed by the incoming radiation, they are replaced at a predetermined frequency by other droplets supplied through the jet streams.

Palmer, Robert B. (Shoreham, NY)

1986-01-01

23

Pulsed power for particle beam accelerators in military applications  

SciTech Connect

Techniques useful for generating and conditioning power for high energy pulsed accelerators with potential weapon applications are described. Pulsed electron accelerators are exemplified by ETA and ATA at Lawrence Livermore Laboratories and RADLAC at Sandia Laboratories Albuquerque. Pulse-power techniques used in other applications are briefly mentioned, including some that may be useful for collective ion accelerators. The limitations of pulse-power and the general directions of desirable development are illustrated. The main needs are to increase repetition rate and to decrease size.

Smith, I.D.

1980-06-20

24

A neutral particle beam system for ITER with RF acceleration  

Microsoft Academic Search

A concept for a current drive system that is based on negative ions with beam energies >1 MeV is presented. Preliminary physics calculations, which are discussed, show that the core current necessary for stability enhancement can be achieved by beams with energy ranging from 1 to 3 MeV. Further study and experiments will better define the optimum energy. Work under

W. L. Stirling; W. R. Becraft; J. H. Whealton; H. H. Haselton

1989-01-01

25

Low energy beam transport for facility for rare isotope beams driver linear particle accelerator  

SciTech Connect

The driver linac for the facility for rare isotope beams (FRIB) will provide a wide range of primary ion beams for nuclear physics research. The linac will be capable of accelerating a uranium beam to an energy of up to 200 Mev/u and delivering it to a fragmentation target with a maximum power of 400 kW. Stable ion beams will be produced by a high performance electron cyclotron resonance ion source operating at 28 GHz. The ion source will be located on a high voltage platform to reach an initial beam energy of 12 keV/u. After extraction, the ion beam will be transported vertically down to the linac tunnel in a low energy beam transport (LEBT) system and injected into a radio frequency quadrupole (RFQ) operating at a frequency of 80.5 MHz. To meet the beam power requirements, simultaneous acceleration of two-charge states will be used for heavier ions ({>=}Xe). This paper presents the layout of the FRIB LEBT and the beam dynamics in the LEBT. In particular, simulation and design of the beam line section before charge state selection will be detailed. The need to use an achromatic design for the charge state selection system and the advantage of an ion beam collimation system to limit the emittance of the beam injected into the RFQ will be discussed in this paper.

Sun, L. T.; Leitner, D.; Machicoane, G.; Pozdeyev, E.; Winklehner, D.; Zhao, Q. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Smirnov, V.; Vorozhtsov, S. B. [Joint Institute for Nuclear Research, Dubna, Moscow 141980 (Russian Federation)

2012-02-15

26

Low energy beam transport for facility for rare isotope beams driver linear particle accelerator  

NASA Astrophysics Data System (ADS)

The driver linac for the facility for rare isotope beams (FRIB) will provide a wide range of primary ion beams for nuclear physics research. The linac will be capable of accelerating a uranium beam to an energy of up to 200 Mev/u and delivering it to a fragmentation target with a maximum power of 400 kW. Stable ion beams will be produced by a high performance electron cyclotron resonance ion source operating at 28 GHz. The ion source will be located on a high voltage platform to reach an initial beam energy of 12 keV/u. After extraction, the ion beam will be transported vertically down to the linac tunnel in a low energy beam transport (LEBT) system and injected into a radio frequency quadrupole (RFQ) operating at a frequency of 80.5 MHz. To meet the beam power requirements, simultaneous acceleration of two-charge states will be used for heavier ions (>=Xe). This paper presents the layout of the FRIB LEBT and the beam dynamics in the LEBT. In particular, simulation and design of the beam line section before charge state selection will be detailed. The need to use an achromatic design for the charge state selection system and the advantage of an ion beam collimation system to limit the emittance of the beam injected into the RFQ will be discussed in this paper.

Sun, L. T.; Leitner, D.; Machicoane, G.; Pozdeyev, E.; Smirnov, V.; Vorozhtsov, S. B.; Winklehner, D.; Zhao, Q.

2012-02-01

27

Low energy beam transport for facility for rare isotope beams driver linear particle accelerator.  

PubMed

The driver linac for the facility for rare isotope beams (FRIB) will provide a wide range of primary ion beams for nuclear physics research. The linac will be capable of accelerating a uranium beam to an energy of up to 200 Mev?u and delivering it to a fragmentation target with a maximum power of 400 kW. Stable ion beams will be produced by a high performance electron cyclotron resonance ion source operating at 28 GHz. The ion source will be located on a high voltage platform to reach an initial beam energy of 12 keV?u. After extraction, the ion beam will be transported vertically down to the linac tunnel in a low energy beam transport (LEBT) system and injected into a radio frequency quadrupole (RFQ) operating at a frequency of 80.5 MHz. To meet the beam power requirements, simultaneous acceleration of two-charge states will be used for heavier ions (?Xe). This paper presents the layout of the FRIB LEBT and the beam dynamics in the LEBT. In particular, simulation and design of the beam line section before charge state selection will be detailed. The need to use an achromatic design for the charge state selection system and the advantage of an ion beam collimation system to limit the emittance of the beam injected into the RFQ will be discussed in this paper. PMID:22380310

Sun, L T; Leitner, D; Machicoane, G; Pozdeyev, E; Smirnov, V; Vorozhtsov, S B; Winklehner, D; Zhao, Q

2012-02-01

28

Pinhole plate diagnostic for neutral particle beam accelerator  

Microsoft Academic Search

An unusual method of forming a foil with highly accurate hole placements and overlayed stripper\\/neutralizer foil allows accurate beam divergence and density diagnostics when used in conjunction with a downstream fluorescent screen and high resolution photography.

Barry L. Barthell; Thomas A. Archuleta

1989-01-01

29

Electrohydrodynamic lithium ion-source experiments on PBFA (Particle Beam Fusion Accelerator) 2  

Microsoft Academic Search

We are developing anodes to test the electrohydrodynamic (EHD) instability as a means of producing an intense lithium beam on Sandia's Particle Beam Fusion Accelerator II. In a strong electric field (â¼10 MV\\/cm) a molten lithium or lithium nitrate surface is predicted to become EHD unstable and deform into a dense array of cusps with sub-micron spacing. Ions field-evaporated from

R. G. Adams; J. R. Woodworth; A. L. Pregenzer; T. R. Lockner; R. A. Gerber; D. J. Johnson; W. H. Jaramillo; M. M. Dillon; R. S. Coats; M. Halliburton; P. Primm; G. Torres; G. Ziska; T. Atwood

1990-01-01

30

Target diagnostics for intense lithium ion hohlraum experiments on Particle Beam Fusion Accelerator II  

Microsoft Academic Search

A review of the diagnostics used at Sandia National Laboratories to measure the parameters of intense lithium ion-beam hohlraum target experiments on Particle Beam Fusion Accelerator II will be presented. This diagnostic package contains an extensive suite of x-ray spectral and imaging diagnostics that enable measurements of target temperature and x-ray output. The x-ray diagnostics include time-integrated and time-resolved pinhole

R. J. Leeper; J. E. Bailey; A. L. Carlson; G. A. Chandler; M. S. Derzon; R. J. Dukart; D. E. Hebron; J. A. Hunter; L. P. Mix; A. R. Moats; T. J. Nash; W. R. Olson; P. D. Rockett; C. L. Ruiz; J. A. Torres; R. W. Olsen; T. L. Barber; P. W. Lake; F. A. Schmidlapp

1995-01-01

31

Plasma opening switch experiments on the Particle Beam Accelerator II  

Microsoft Academic Search

Summary form only. The authors have developed and tested three different plasma-opening switch (POS) designs that use magnetic fields to control and confine the injected plasma. All three configurations couple current efficiently to a 5-? electron beam diode. In the first switch, a plasma generated by flashboard sources is injected into the 20-? magnetically insulated transmission line through six equally

M. A. Sweeney; D. H. McDaniel; C. W. Mendel; G. E. Rochau; W. B. S. Moore; G. R. Mowrer; W. W. Simpson; D. M. Zagar; T. Grasser; C. D. McDougal

1989-01-01

32

Automated detection and analysis of particle beams in laser-plasma accelerator simulations  

SciTech Connect

Numerical simulations of laser-plasma wakefield (particle) accelerators model the acceleration of electrons trapped in plasma oscillations (wakes) left behind when an intense laser pulse propagates through the plasma. The goal of these simulations is to better understand the process involved in plasma wake generation and how electrons are trapped and accelerated by the wake. Understanding of such accelerators, and their development, offer high accelerating gradients, potentially reducing size and cost of new accelerators. One operating regime of interest is where a trapped subset of electrons loads the wake and forms an isolated group of accelerated particles with low spread in momentum and position, desirable characteristics for many applications. The electrons trapped in the wake may be accelerated to high energies, the plasma gradient in the wake reaching up to a gigaelectronvolt per centimeter. High-energy electron accelerators power intense X-ray radiation to terahertz sources, and are used in many applications including medical radiotherapy and imaging. To extract information from the simulation about the quality of the beam, a typical approach is to examine plots of the entire dataset, visually determining the adequate parameters necessary to select a subset of particles, which is then further analyzed. This procedure requires laborious examination of massive data sets over many time steps using several plots, a routine that is unfeasible for large data collections. Demand for automated analysis is growing along with the volume and size of simulations. Current 2D LWFA simulation datasets are typically between 1GB and 100GB in size, but simulations in 3D are of the order of TBs. The increase in the number of datasets and dataset sizes leads to a need for automatic routines to recognize particle patterns as particle bunches (beam of electrons) for subsequent analysis. Because of the growth in dataset size, the application of machine learning techniques for scientific data mining is increasingly considered. In plasma simulations, Bagherjeiran et al. presented a comprehensive report on applying graph-based techniques for orbit classification. They used the KAM classifier to label points and components in single and multiple orbits. Love et al. conducted an image space analysis of coherent structures in plasma simulations. They used a number of segmentation and region-growing techniques to isolate regions of interest in orbit plots. Both approaches analyzed particle accelerator data, targeting the system dynamics in terms of particle orbits. However, they did not address particle dynamics as a function of time or inspected the behavior of bunches of particles. Ruebel et al. addressed the visual analysis of massive laser wakefield acceleration (LWFA) simulation data using interactive procedures to query the data. Sophisticated visualization tools were provided to inspect the data manually. Ruebel et al. have integrated these tools to the visualization and analysis system VisIt, in addition to utilizing efficient data management based on HDF5, H5Part, and the index/query tool FastBit. In Ruebel et al. proposed automatic beam path analysis using a suite of methods to classify particles in simulation data and to analyze their temporal evolution. To enable researchers to accurately define particle beams, the method computes a set of measures based on the path of particles relative to the distance of the particles to a beam. To achieve good performance, this framework uses an analysis pipeline designed to quickly reduce the amount of data that needs to be considered in the actual path distance computation. As part of this process, region-growing methods are utilized to detect particle bunches at single time steps. Efficient data reduction is essential to enable automated analysis of large data sets as described in the next section, where data reduction methods are steered to the particular requirements of our clustering analysis. Previously, we have described the application of a set of algorithms to automate the data analys

Ushizima, Daniela Mayumi; Geddes, C.G.; Cormier-Michel, E.; Bethel, E. Wes; Jacobsen, J.; Prabhat, ,; R.ubel, O.; Weber, G,; Hamann, B.

2010-05-21

33

Test of pixel detectors for laser-driven accelerated particle beams  

NASA Astrophysics Data System (ADS)

Laser-driven accelerated (LDA) particle beams have due to the unique acceleration process very special properties. In particular they are created in ultra-short bunches of high intensity exceeding more than 107 \\frac{particles}{cm^{2} \\cdot ns} per bunch. Characterization of these beams is very limited with conventional particle detectors. Non-electronic detectors such as imaging plates or nuclear track detectors are, therefore, conventionally used at present. Moreover, all these detectors give only offline information about the particle pulse position and intensity as they require minutes to hours to be processed, calling for a new highly sensitive online device. Here, we present tests of different pixel detectors for real time detection of LDA ion pulses. Experiments have been performed at the Munich 14MV Tandem accelerator with 8-20 MeV protons in dc and pulsed beam, the latter producing comparable flux as a LDA ion pulse. For detection tests we chose the position-sensitive quantum-counting semiconductor pixel detector Timepix which also provides per-pixel energy- or time-sensitivity. Additionally other types of commercially available pixel detectors are being evaluated such as the RadEye™1, a large area (25 x 50 mm2) CMOS image sensor. All of these devices are able to resolve individual ions with high spatial- and energy-resolution down to the level of ?m and tens of keV, respectively. Various beam delivering parameters of the accelerator were thus evaluated and verified. The different readout modes of the Timepix detector which is operated with an integrated USB-based readout interface allow online visualization of single and time-integrated events. Therefore Timepix offers the greatest potential in analyzing the beam parameters.

Reinhardt, S.; Granja, C.; Krejci, F.; Assmann, W.

2011-12-01

34

Amps particle accelerator definition study  

NASA Technical Reports Server (NTRS)

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

Sellen, J. M., Jr.

1975-01-01

35

Particle acceleration  

NASA Technical Reports Server (NTRS)

Data is compiled from Solar Maximum Mission and Hinothori satellites, particle detectors in several satellites, ground based instruments, and balloon flights in order to answer fundamental questions relating to: (1) the requirements for the coronal magnetic field structure in the vicinity of the energization source; (2) the height (above the photosphere) of the energization source; (3) the time of energization; (4) transistion between coronal heating and flares; (5) evidence for purely thermal, purely nonthermal and hybrid type flares; (6) the time characteristics of the energization source; (7) whether every flare accelerates protons; (8) the location of the interaction site of the ions and relativistic electrons; (9) the energy spectra for ions and relativistic electrons; (10) the relationship between particles at the Sun and interplanetary space; (11) evidence for more than one acceleration mechanism; (12) whether there is single mechanism that will accelerate particles to all energies and also heat the plasma; and (13) how fast the existing mechanisms accelerate electrons up to several MeV and ions to 1 GeV.

Vlahos, L.; Machado, M. E.; Ramaty, R.; Murphy, R. J.; Alissandrakis, C.; Bai, T.; Batchelor, D.; Benz, A. O.; Chupp, E.; Ellison, D.

1986-01-01

36

Target diagnostics for intense lithium ion hohlraum experiments on Particle Beam Fusion Accelerator II  

SciTech Connect

A review of the diagnostics used at Sandia National Laboratories to measure the parameters of intense lithium ion-beam hohlraum target experiments on Particle Beam Fusion Accelerator II will be presented. This diagnostic package contains an extensive suite of x-ray spectral and imaging diagnostics that enable measurements of target temperature and x-ray output. The x-ray diagnostics include time-integrated and time-resolved pinhole cameras, energy-resolved one-dimensional streaked imaging diagnostics, time-integrated and time-resolved grazing incidence spectrographs, a transmission grating spectrograph, an elliptical crystal spectrograph, a bolometer array, an 11- element x-ray diode array, and an 11-element PIN diode detector array. The incident Li beam symmetry and an estimate of incident Li beam power density can be measured from ion beam-induced characteristic x-ray line emission and neutron emission.

Leeper, R.J.; Bailey, J.E.; Carlson, A.L.; Chandler, G.A.; Derzon, M.S.; Dukart, R.J.; Hebron, D.E.; Hunter, J.A.; Mix, L.P.; Moats, A.R.; Nash, T.J.; Olson, W.R.; Rockett, P.D.; Ruiz, C.L.; Torres, J.A.; Wenger, D.F. (Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)); Olsen, R.W. (EG G Energy Measurements, Kirtland Operations, Albuquerque, New Mexico 87196 (United States)); Barber, T.L.; Lake, P.W.; Schmidlapp, F.A. (Ktech Corporation, Albuquerque, New Mexico 87110 (United States))

1995-01-01

37

3D particle simulations of space-charge-dominated beams in HIF accelerator experiments  

SciTech Connect

The development of a high current, heavy-ion beam for inertial confinement fusion requires a detailed understanding of the behavior of the beam, including effects of the large self-fields. This necessity makes particle-in-cell (PIC) simulation the appropriate tool, and for this reason, the three-dimensional PIC/accelerator code WARP3d is being developed. WARP3d has been used extensively to study the creation and propagation of ion beams both to support experiments and for the understanding of basic beam physics. An overview of the structure of the code is presented along with a discussion of features that make the code an effective tool in the understanding of space-charge dominated beam behavior. A number of applications where WARP3d has played an important role is discussed, emphasizing the need of three-dimensional, first principles simulations. Results and comparisons with experiment are presented.

Grote, D.P.; Friedman, A.; Lund, S.M. [Lawrence Livermore National Lab., CA (United States); Haber, I. [Naval Research Lab., Washington, DC (United States)

1997-05-01

38

Artificial intelligence research in particle accelerator control systems for beam line tuning  

SciTech Connect

Tuning particle accelerators is time consuming and expensive, with a number of inherently non-linear interactions between system components. Conventional control methods have not been successful in this domain and the result is constant and expensive monitoring of the systems by human operators. This is particularly true for the start-up and conditioning phase after a maintenance period or an unexpected fault. In turn, this often requires a step-by-step restart of the accelerator. Surprisingly few attempts have been made to apply intelligent accelerator control techniques to help with beam tuning, fault detection, and fault recovery problems. The reason for that might be that accelerator facilities are rare and difficult to understand systems that require detailed expert knowledge about the underlying physics as well as months if not years of experience to understand the relationship between individual components, particularly if they are geographically disjoint. This paper will give an overview about the research effort in the accelerator community that has been dedicated to the use of artificial intelligence methods for accelerator beam line tuning.

Pieck, Martin [Los Alamos National Laboratory

2008-01-01

39

Neutral particle beam intensity controller  

Microsoft Academic Search

A neutral beam generator is described wherein an energetic neutral particle beam is formed from a focused beam of ions accelerated along a beam axis into a neutralizer cell disposed about the beam axis, a neutral beam intensity controller. The controller consists of: a neutral particle beam dump disposed with a beam dump surface transverse to the beam axis downstream

Dagenhart

1986-01-01

40

Object-Oriented Parallel Particle-in-Cell Code for Beam Dynamics Simulation in Linear Accelerators  

SciTech Connect

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.

Qiang, J.; Ryne, R.D.; Habib, S.; Decky, V.

1999-11-13

41

Three-dimensional, particle-in-cell simulations of applied-B ion diodes on the particle beam fusion accelerator II  

Microsoft Academic Search

We have used the three-dimensional, particle-in-cell code QUICKSILVER [J. P. Quintenz, {ital et} {ital al}., Lasers and Particle Beams {bold 12}, 283 (1994)] to simulate radial applied-{ital B} ion diodes on the particle beam fusion accelerator II at Sandia National Laboratories. The simulations agree well with experiments early in the beam pulse, but differ substantially as the ion-beam current increases.

T. D. Pointon; M. P. Desjarlais

1996-01-01

42

Three-dimensional, particle-in-cell simulations of applied-B ion diodes on the particle beam fusion accelerator II  

Microsoft Academic Search

We have used the three-dimensional, particle-in-cell code QUICKSILVER [J. P. Quintenz, etal., Lasers and Particle Beams 12, 283 (1994)] to simulate radial applied-B ion diodes on the particle beam fusion accelerator II at Sandia National Laboratories. The simulations agree well with experiments early in the beam pulse, but differ substantially as the ion-beam current increases. This is attributed to the

T. D. Pointon; M. P. Desjarlais

1996-01-01

43

Technical Challenges and Scientific Payoffs of Muon BeamAccelerators for Particle Physics  

SciTech Connect

Historically, progress in particle physics has largely beendetermined by development of more capable particle accelerators. Thistrend continues today with the recent advent of high-luminosityelectron-positron colliders at KEK and SLAC operating as "B factories,"the imminent commissioning of the Large Hadron Collider at CERN, and theworldwide development effort toward the International Linear Collider.Looking to the future, one of the most promising approaches is thedevelopment of muon-beam accelerators. Such machines have very highscientific potential, and would substantially advance thestate-of-the-art in accelerator design. A 20-50 GeV muon storage ringcould serve as a copious source of well-characterized electron neutrinosor antineutrinos (a Neutrino Factory), providing beams aimed at detectorslocated 3000-7500 km from the ring. Such long baseline experiments areexpected to be able to observe and characterize the phenomenon ofcharge-conjugation-parity (CP) violation in the lepton sector, and thusprovide an answer to one of the most fundamental questions in science,namely, why the matter-dominated universe in which we reside exists atall. By accelerating muons to even higher energies of several TeV, we canenvision a Muon Collider. In contrast with composite particles likeprotons, muons are point particles. This means that the full collisionenergy is available to create new particles. A Muon Collider has roughlyten times the energy reach of a proton collider at the same collisionenergy, and has a much smaller footprint. Indeed, an energy frontier MuonCollider could fit on the site of an existing laboratory, such asFermilab or BNL. The challenges of muon-beam accelerators are related tothe facts that i) muons are produced as a tertiary beam, with very large6D phase space, and ii) muons are unstable, with a lifetime at rest ofonly 2 microseconds. How these challenges are accommodated in theaccelerator design will be described. Both a Neutrino Factory and a MuonCollider require large numbers of challenging superconducting magnets,including large aperture solenoids, closely spaced solenoids withopposing fields, shielded solenoids, very high field (~;40-50 T)solenoids, and storage ring magnets with a room-temperature midplanesection. Uses for the various magnets will be outlined, along withR&D plans to develop these and other required components of suchmachines.

Zisman, Michael S.

2007-09-25

44

Particle acceleration fields derived from a wavefront-divided laser beam  

NASA Astrophysics Data System (ADS)

In a crossed-laser-beam linear accelerator, the longitudinal acceleration field is obtained by crossing two fundamental Gaussian laser beams with a ? phase difference from one another. We show by numerical calculation that a comparable acceleration field can be obtained by crossing two half-Gaussian laser beams wavefront-divided from a fundamental Gaussian laser beam. Since the relative phase between the two wavefront-divided, half-Gaussian beams is determined by a dielectric step at the splitting point, the ? relative phase can be preserved even though background acoustic noises are present.

Huang, Y. C.

1998-12-01

45

Principles of Charged Particle Acceleration  

NSDL National Science Digital Library

This learning resources comprise a healthy introduction to charged particle acceleration. The site, by Stanley Humphries, a professor of electrical and computer engineering at University of New Mexico, amounts to an online textbook (.pdf) introducing the theory of charged particle acceleration. The book's fifteen chapters (with bibliography) summarize "the principles underlying all particle accelerators" and provide "a reference collection of equations and material essential to accelerator development and beam applications."

46

Simulation Studies of Particle Acceleration Powered by Modulated Intense Relativistic Electron Beams.  

National Technical Information Service (NTIS)

A time dependent, fully electromagnetic particle code is used to simulate transfer of energy from an annular modulated intense relativistic electron beam to a low current electron beam via a disk-loaded structure. It is shown that an intense beam may be u...

J. Krall M. Friedman V. Serlin Y. Y. Lau

1989-01-01

47

Introduction to the measurement of noise with application to particle accelerator beam stabilization  

Microsoft Academic Search

One of the most important figures of merit for a synchrotron radiation source, once specified beam intensity and energy have been achieved, is charged particle beam stability. While a significant effort has been expended at the Advanced Photon Source (APS) to reduce or eliminate undesirable sources of beam motion, it will be necessary to employ active feedback to stabilize the

Decker

1998-01-01

48

New techniques for particle accelerators  

SciTech Connect

A review is presented of the new techniques which have been proposed for use in particle accelerators. Attention is focused upon those areas where significant progress has been made in the last two years--in particular, upon two-beam accelerators, wakefield accelerators, and plasma focusers. 26 refs., 5 figs., 1 tab.

Sessler, A.M.

1990-06-01

49

Means for the focusing and acceleration of parallel beams of charged particles. [Patent application  

DOEpatents

Apparatus for focusing beams of charged particles comprising planar arrays of electrostatic quadrupoles. The array may be assembled from a single component which comprises a support plate containing uniform rows of poles. Each pole is separated by a hole through the plate designed to pass a beam. Two such plates may be positioned with their poles intermeshed to form a plurality of quadrupoles.

Maschke, A.W.

1980-09-23

50

A stochastic model for the semiclassical collective dynamics of charged beams in particle accelerators  

Microsoft Academic Search

A recent proposal (see quant-ph\\/9803068) to simulate semiclassical\\u000acorrections to classical dynamics by suitable classical stochastic fluctuations\\u000ais applied to the specific instance of charged beam dynamics in particle\\u000aaccelerators. The resulting picture is that the collective beam dynamics, at\\u000athe leading semiclassical order in Planck constant can be described by a\\u000aparticular diffusion process, the Nelson process, which is

Salvatore De Martino; Silvio De Siena; Fabrizio Illuminati

1998-01-01

51

Two-Beam Accelerator.  

National Technical Information Service (NTIS)

The Two-Beam Accelerator (TBA) consists of a long high-gradient accelerator structure (HGS) adjacent to an equal-length Free Electron Laser (FEL). In the FEL, a beam propagates through a long series of undulators. At regular intervals, waveguides couple m...

A. M. Sessler D. B. Hopkins

1986-01-01

52

Two-Beam Accelerator.  

National Technical Information Service (NTIS)

The Two-Beam Accelerator (TBA) consists of a long high-gradient accelerator structure (HGS) adjacent to an equal-length Free Electron Laser (FEL). In the FEL, a beam propagates through a long series of undulators. At regular intervals, waveguides couple m...

A. M. Sessler D. B. Hopkins

1987-01-01

53

Production of high power microwaves for particle acceleration with an FEL bunched electron beam  

NASA Astrophysics Data System (ADS)

Among the studies in the framework of high gradient linear electron-positron collider research, the Two-Beam Accelerator (TBA) is a very promising concept, and two projects are in progress, the Compact Linear Collider project at CERN (W. Schnell, Report no. CERN SL/92-51 and CLIC note 184; K. Hübner, CERN/PS 92-43, CLIC note 176; S. Van der Meer, CERN/PS 89-50, CLIC note 97.) and the Relativistic Klystron-TBA project at LBNL (Technical Review Committee, International Linear Collider Technical Review Committee Report 1995, SLAC-R-95-471, 1995). In a TBA an extremely intense low-energy electron beam, called the drive beam, is bunched at the desired operating frequency, and upon passing through resonant cavities generates radio-frequency power for accelerating the main beam. Among the different approaches to the production of a suitable drive beam, the use of an FEL has been proposed and is under active study at CEA/CESTA.

Gardelle, J.; Lefevre, T.; Marchese, G.; Padois, M.; Rullier, J. L.; Donohue, J. T.

1999-06-01

54

Acceleration and Compression of Charged Particle Bunches Using Counter-Propagating Laser Beams  

SciTech Connect

The nonlinear interaction between counter-propagating laser beams in a plasma results in the generation of large (enhanced) plasma wakes. The two beams need to be slightly detuned in frequency, and one of them has to be ultra-short (shorter than a plasma period). Thus produced wakes have a phase velocity close to the speed of light and can be used for acceleration and compression of charged bunches. The physical mechanism responsible for the enhanced wake generation is qualitatively described and compared with the conventional laser wakefield mechanism. The authors also demonstrate that, depending on the sign of the frequency difference between the lasers, the enhanced wake can be used as a ``snow-plow'' to accelerate and compress either positively or negatively charged bunches. This ability can be utilized in an electron-positron injector.

G. Shvets; N. J. Fisch; A. Pukhov

2000-10-17

55

Lithium ion source experiments on PBFA II (Particle Beam Fusion Accelerator II)  

Microsoft Academic Search

In conjunction with Applied-B ion diode focusing experiments on PBFA II, we are beginning lithium ion source experiments with a solid lithium fluoride ''field-enhanced'' source and a liquid electrohydrodynamic (EHD) source. In addition to the conventional electrical measurements, particle diagnostics include a Thomson parabola ion analyzer, nuclear activation, and an ion pinhole camera to measure lithium ion beam energy, purity,

K. W. Bieg; T. R. Lockner; A. L. Pregenzer; J. R. Woodworth; M. P. Desjarlais; R. A. Gerber; D. J. Johnson; R. J. Leeper; J. E. Maenchen; P. F. McKay

1988-01-01

56

Electrostatic wire stabilizing a charged particle beam  

DOEpatents

In combination with a charged particle beam generator and accelerator, apparatus and method are provided for stabilizing a beam of electrically charged particles. A guiding means, disposed within the particle beam, has an electric charge induced upon it by the charged particle beam. Because the sign of the electric charge on the guiding means and the sign of the particle beam are opposite, the particles are attracted toward and cluster around the guiding means to thereby stabilize the particle beam as it travels.

Prono, D.S.; Caporaso, G.J.; Briggs, R.J.

1983-03-21

57

Three-dimensional, particle-in-cell simulations of applied-B ion diodes on the particle beam fusion accelerator II  

SciTech Connect

We have used the three-dimensional, particle-in-cell code QUICKSILVER [J. P. Quintenz, {ital et} {ital al}., Lasers and Particle Beams {bold 12}, 283 (1994)] to simulate radial applied-{ital B} ion diodes on the particle beam fusion accelerator II at Sandia National Laboratories. The simulations agree well with experiments early in the beam pulse, but differ substantially as the ion-beam current increases. This is attributed to the oversimplified ion emission model. We see the same instabilities seen in earlier simulations with idealized diode geometries; Early in time there is a diocotron instability, followed by a transition to an {open_quote}{open_quote}ion mode{close_quote}{close_quote} instability at much lower frequency. The instability-induced beam divergence for the {approximately}10 MeV beam during the diocotron phase is {lt}10 mrad, significantly less than the total beam divergence in experiments early in the pulse, but increases to {approx_gt}25 mrad after the transition. The ion mode has a distinct harmonic structure along the applied field lines, making the instability transition sensitive to the diode geometry. The ion mode instability in our latest simulations is consistent with evidence of instabilities from recent experiments. {copyright} {ital 1996 American Institute of Physics.}

Pointon, T.D.; Desjarlais, M.P. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

1996-08-01

58

Physics of Particle Acceleration.  

National Technical Information Service (NTIS)

The development of particle accelerators was reviewed with regard to energy and cost. The problems of funding much larger and slower particle accelerators was considered. The question of new ideas and techniques was raised and, with this in mind, the vari...

J. D. Lawson

1982-01-01

59

Fusion reactions initiated by laser-accelerated particle beams in a laser-produced plasma  

NASA Astrophysics Data System (ADS)

The advent of high-intensity-pulsed laser technology enables the generation of extreme states of matter under conditions that are far from thermal equilibrium. This in turn could enable different approaches to generating energy from nuclear fusion. Relaxing the equilibrium requirement could widen the range of isotopes used in fusion fuels permitting cleaner and less hazardous reactions that do not produce high-energy neutrons. Here we propose and implement a means to drive fusion reactions between protons and boron-11 nuclei by colliding a laser-accelerated proton beam with a laser-generated boron plasma. We report proton-boron reaction rates that are orders of magnitude higher than those reported previously. Beyond fusion, our approach demonstrates a new means for exploring low-energy nuclear reactions such as those that occur in astrophysical plasmas and related environments.

Labaune, C.; Baccou, C.; Depierreux, S.; Goyon, C.; Loisel, G.; Yahia, V.; Rafelski, J.

2013-10-01

60

Neutral particle beam intensity controller  

SciTech Connect

A neutral beam generator is described wherein an energetic neutral particle beam is formed from a focused beam of ions accelerated along a beam axis into a neutralizer cell disposed about the beam axis, a neutral beam intensity controller. The controller consists of: a neutral particle beam dump disposed with a beam dump surface transverse to the beam axis downstream of the neutralizer and having an opening therethrough for the passage of neutral particles focused along the beam axis; means for generating a magnetic field within the neutralizer perpendicular to the beam axis adjacent to the upstream end of the neutralizer; and control means operatively connected to the magnetic field generating means for selectively controlling the intensity of the magnetic field within the neutralizer in order to defocus a portion of the beam ions prior to neutralization in the neutralizer to direct the neutral particles generated from the defocused portion of the ion beam along paths which are intercepted by the beam dump surface of the beam dump, thereby controlling the intensity of neutral particles passing through the opening in the beam dump.

Dagenhart, W.K.

1986-06-24

61

Accelerator system and method of accelerating particles  

NASA Technical Reports Server (NTRS)

An accelerator system and method that utilize dust as the primary mass flux for generating thrust are provided. The accelerator system can include an accelerator capable of operating in a self-neutralizing mode and having a discharge chamber and at least one ionizer capable of charging dust particles. The system can also include a dust particle feeder that is capable of introducing the dust particles into the accelerator. By applying a pulsed positive and negative charge voltage to the accelerator, the charged dust particles can be accelerated thereby generating thrust and neutralizing the accelerator system.

Wirz, Richard E. (Inventor)

2010-01-01

62

Focus on Accelerator and Beam Physics  

Microsoft Academic Search

For more than 50 years, particle accelerators have driven fundamental discoveries in many areas of scientific research. The discovery of elementary particles, the nature of fundamental forces and fields and the enormous increase of knowledge in nuclear physics would not have been possible without the progress of accelerator physics and technology in providing bright, intense and high energy beams of

Georg Hoffstaetter; Kwang-Je Kim; Ferdinand Willeke

2006-01-01

63

Particle acceleration in flares  

NASA Technical Reports Server (NTRS)

Particle acceleration is intrinsic to the primary energy release in the impulsive phase of solar flares, and we cannot understand flares without understanding acceleration. New observations in soft and hard X-rays, gamma-rays and coherent radio emissions are presented, suggesting flare fragmentation in time and space. X-ray and radio measurements exhibit at least five different time scales in flares. In addition, some new observations of delayed acceleration signatures are also presented. The theory of acceleration by parallel electric fields is used to model the spectral shape and evolution of hard X-rays. The possibility of the appearance of double layers is further investigated.

Benz, Arnold O.; Kosugi, Takeo; Aschwanden, Markus J.; Benka, Steve G.; Chupp, Edward L.; Enome, Shinzo; Garcia, Howard; Holman, Gordon D.; Kurt, Victoria G.; Sakao, Taro

1994-01-01

64

Light ion sources and target results on PBFA II (Particle Beam Fusion Accelerator II)  

Microsoft Academic Search

Advances in ion beam theory, diagnostics, and experiments in the past two years have enabled efficient generation of intense proton beams on PBFA II, and focusing of the beam power to 5.4 TW\\/cm² on a 6-mm-diameter target. Target experiments have been started with the intense proton beams, since the range of protons at 4--5 MeV is equivalent to that of

D. L. Cook; J. E. Bailey; K. W. Bieg; D. D. Bloomquist; R. S. Coats; G. C. Chandler; M. E. Cuneo; M. S. Derzon; M. P. Desjarlais; P. L. Dreike; R. J. Dukart; R. A. Gerber; D. J. Johnson; R. J. Leeper; T. R. Lockner; D. H. McDaniel; J. E. Maenchen; M. K. Matzen; T. A. Mehlhorn; L. P. Mix; A. R. Moats; W. E. Nelson; T. D. Pointon; A. L. Pregenzer; J. P. Quintenz; T. J. Renk; S. E. Rosenthal; C. L. Ruiz; S. A. Slutz; R Stinnett

1990-01-01

65

Particle Beam Radiography  

NASA Astrophysics Data System (ADS)

Particle beam radiography, which uses a variety of particle probes (neutrons, protons, electrons, gammas and potentially other particles) to study the structure of materials and objects noninvasively, is reviewed, largely from an accelerator perspective, although the use of cosmic rays (mainly muons but potentially also high-energy neutrinos) is briefly reviewed. Tomography is a form of radiography which uses multiple views to reconstruct a three-dimensional density map of an object. There is a very wide range of applications of radiography and tomography, from medicine to engineering and security, and advances in instrumentation, specifically the development of electronic detectors, allow rapid analysis of the resultant radiographs. Flash radiography is a diagnostic technique for large high-explosive-driven hydrodynamic experiments that is used at many laboratories. The bremsstrahlung radiation pulse from an intense relativistic electron beam incident onto a high-Z target is the source of these radiographs. The challenge is to provide radiation sources intense enough to penetrate hundreds of g/cm2 of material, in pulses short enough to stop the motion of high-speed hydrodynamic shocks, and with source spots small enough to resolve fine details. The challenge has been met with a wide variety of accelerator technologies, including pulsed-power-driven diodes, air-core pulsed betatrons and high-current linear induction accelerators. Accelerator technology has also evolved to accommodate the experimenters' continuing quest for multiple images in time and space. Linear induction accelerators have had a major role in these advances, especially in providing multiple-time radiographs of the largest hydrodynamic experiments.

Peach, Ken; Ekdahl, Carl

2014-02-01

66

Light ion sources and target results on PBFA II (Particle Beam Fusion Accelerator II)  

SciTech Connect

Advances in ion beam theory, diagnostics, and experiments in the past two years have enabled efficient generation of intense proton beams on PBFA II, and focusing of the beam power to 5.4 TW/cm{sup 2} on a 6-mm-diameter target. Target experiments have been started with the intense proton beams, since the range of protons at 4--5 MeV is equivalent to that of lithium at 30 MeV. Three series of experiments have been conducted using planar, conical, and cylindrical targets. These tests have provided information on ion beam power density, uniformity, and energy deposition. In order to increase the power density substantially for target implosion experiments, we are now concentrating on development of high voltage lithium ion beams. 10 refs., 13 figs.

Cook, D.L.; Bailey, J.E.; Bieg, K.W.; Bloomquist, D.D.; Coats, R.S.; Chandler, G.C.; Cuneo, M.E.; Derzon, M.S.; Desjarlais, M.P.; Dreike, P.L.; Dukart, R.J.; Gerber, R.A.; Johnson, D.J.; Leeper, R.J.; Lockner, T.R.; McDaniel, D.H.; Maenchen, J.E.; Matzen, M.K.; Mehlhorn, T.A.; Mix, L.P.; Moats, A.R.; Nelson, W.E.; Pointon, T.D.; Pregenzer, A.L.; Quintenz, J.P.; Renk, T.J.; Rosenthal, S.E.; Ruiz, C.L.; Slutz, S.A.; Stinnett, R

1990-01-01

67

Beam-intensity limitations in linear accelerators  

SciTech Connect

Recent demand for high-intensity beams of various particles has renewed interest in the investigation of beam current and beam quality limits in linear RF and induction accelerators and beam-transport channels. Previous theoretical work is reviewed, and new work on beam matching and stability is outlined. There is a real need for extending the theory to handle the time evolution of beam emittance; some present work toward this goal is described. The role of physical constraints in channel intensity limitation is emphasized. Work on optimizing channel performance, particularly at low particle velocities, has resulted in major technological advances. The opportunities for combining such channels into arrays are discussed. 50 references.

Jameson, R.A.

1981-01-01

68

Neutral particle beam intensity controller  

DOEpatents

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

Dagenhart, William K. (Oak Ridge, TN)

1986-01-01

69

Particle acceleration in solar flares  

NASA Technical Reports Server (NTRS)

The most direct signatures of particle acceleration in flares are energetic particles detected in interplanetary space and in the Earth atmosphere, and gamma rays, neutrons, hard X-rays, and radio emissions produced by the energetic particles in the solar atmosphere. The stochastic and shock acceleration theories in flares are reviewed and the implications of observations on particle energy spectra, particle confinement and escape, multiple acceleration phases, particle anistropies, and solar atmospheric abundances are discussed.

Ramaty, R.; Forman, M. A.

1987-01-01

70

Method and apparatus for varying accelerator beam output energy  

DOEpatents

A coupled cavity accelerator (CCA) accelerates a charged particle beam with rf energy from a rf source. An input accelerating cavity receives the charged particle beam and an output accelerating cavity outputs the charged particle beam at an increased energy. Intermediate accelerating cavities connect the input and the output accelerating cavities to accelerate the charged particle beam. A plurality of tunable coupling cavities are arranged so that each one of the tunable coupling cavities respectively connect an adjacent pair of the input, output, and intermediate accelerating cavities to transfer the rf energy along the accelerating cavities. An output tunable coupling cavity can be detuned to variably change the phase of the rf energy reflected from the output coupling cavity so that regions of the accelerator can be selectively turned off when one of the intermediate tunable coupling cavities is also detuned.

Young, Lloyd M. (Los Alamos, NM)

1998-01-01

71

IEC accelerator beam coordinate transformations for clinical Monte Carlo simulation from a phase space or full BEAMnrc particle source  

Microsoft Academic Search

Monte Carlo simulation of clinical treatment plans require, in general, a coordinate transformation to describe the incident\\u000a radiation field orientation on a patient phantom coordinate system. The International Electrotechnical Commission (IEC) has\\u000a defined an accelerator coordinate system along with positive directions for gantry, couch and collimator rotations. In order\\u000a to describe the incident beam’s orientation with respect to the patient’s

Karl K. BushSergei; Sergei F. Zavgorodni

2010-01-01

72

THE TWO-BEAM ACCELERATOR  

SciTech Connect

A Two-Beam Accelerator, in which one of the beams is an intense low energy beam made to undergo free electron lasing and the other beam is a compact bunch of high energy electrons, is shown to be an interesting possibility for a linear collider.

Hopkins, D.B.; Sessler, A.M.; Wurtele, J.S.

1984-04-01

73

IEC accelerator beam coordinate transformations for clinical Monte Carlo simulation from a phase space or full BEAMnrc particle source.  

PubMed

Monte Carlo simulation of clinical treatment plans require, in general, a coordinate transformation to describe the incident radiation field orientation on a patient phantom coordinate system. The International Electrotechnical Commission (IEC) has defined an accelerator coordinate system along with positive directions for gantry, couch and collimator rotations. In order to describe the incident beam's orientation with respect to the patient's coordinate system, DOSXYZnrc simulations often require transformation of the accelerator's gantry, couch and collimator angles to describe the incident beam. Similarly, versions of the voxelized Monte Carlo code (VMC(++)) require non-trivial transformation of the accelerator's gantry, couch and collimator angles to standard Euler angles ?, ?, ?, to describe an incident phase space source orientation with respect to the patient's coordinate system. The transformations, required by each of these Monte Carlo codes to transport phase spaces through a phantom, have been derived with a rotation operator approach. The transformations have been tested and verified against the Eclipse treatment planning system. PMID:21053115

Bush, Karl K; Zavgorodni, Sergei F

2010-12-01

74

Particle Acceleration With a Wiggling Field  

NASA Astrophysics Data System (ADS)

A novel method of high rate far-field laser acceleration of electron beams is proposed. It is based on a resonance interaction of straightforward charged particle beam passing through wiggling propagation of electromagnetic wave. Electromagnetic beam guiding can be provided in vacuum by periodically curved waveguide or in overdense plasma channels under stimulated hose instability. Main parameters of acceleration process are estimated. The method proposed provides low energy ( 10MeV) electrons capture, absence of conventional undulator, absence of synchrotron radiation losses and enhanced acceleration rate compared with Inversed Free Electron Laser (IFEL).

Smirnov, A. V.

1997-05-01

75

Electrostatic wire for stabilizing a charged particle beam  

DOEpatents

In combination with a charged particle beam generator and accelerator, apparatus and method are provided for stabilizing a beam of electrically charged particles. A guiding means, disposed within the particle beam, has an electric charge induced upon it by the charged particle beam. Because the sign of the electric charge on the guiding means and the sign of the particle beam are opposite, the particles are attracted toward and cluster around the guiding means to thereby stabilize the particle beam as it travels.

Prono, Daniel S. (Livermore, CA); Caporaso, George J. (Livermore, CA); Briggs, Richard J. (Livermore, CA)

1985-01-01

76

Acceleration of polarized proton beams  

SciTech Connect

The acceleration of polarized beams in circular accelerators is complicated by the numerous depolarizing spin resonances. Using a partial Siberian snake and a rf dipole that ensure stable adiabatic spin motion during acceleration has made it possible to accelerate polarized protons to 25 GeV at the Brookhaven AGS. Full Siberian snakes are being developed for RHIC to make the acceleration of polarized protons to 250 GeV possible. A similar scheme is being studied for the 800 GeV HERA proton accelerator.

Roser, T.

1998-12-31

77

Particle beam current measurement system  

US Patent & Trademark Office Database

A method and apparatus for measuring the beam current of a particle beam in an accelerator by charging the capacitor across an operational amplifier and controlling the scaling of the amplifier output with a programmable gain amplifier (PGA). The out put of the (PGA) is sampled and storing with an analog-to-digital converter to acquire and store at least two digital voltage values. The two digital voltage values are using to obtain a value proportional to beam current. A field programmable gate array is used to implement digital logic to sample and hold output from the analog-to-digital converter.

2008-03-04

78

Particle Acceleration in Hypernova Explosion  

NASA Astrophysics Data System (ADS)

The relativistic shock break out at the surface of Hypernova star is considered. The hydrodynamical acceleration of outer layers of Hypernova envelope is investigated. The characteristics of accelerated particles are estimated.

Marchenko, V. V.; Hnatyk, B. I.; Pekur, D. V.

2009-12-01

79

Particle Acceleration in Hypernova Explosion  

Microsoft Academic Search

The relativistic shock break out at the surface of Hypernova star is considered. The hydrodynamical acceleration of outer layers of Hypernova envelope is investigated. The characteristics of accelerated particles are estimated.

V. V. Marchenko; B. I. Hnatyk; D. V. Pekur

2009-01-01

80

Transverse motion of single particles in accelerators  

SciTech Connect

Any accelerator must have focusing elements, usually magnetic quadrupoles, which hold individual particles close to an ideal central orbit. The purpose of this chapter is to analyse the transverse motion of particles and beams in such systems, with particular emphasis on circular machines. A particle not precisely on the central orbit is subject to a restoring force tending to reduce the deviation and, as a result, the particle oscillates around the central orbit. These oscillations are usually called betatron oscillations when they occur in a circular machine, and we will use the same terminology even for motion in any beam transport system. (AIP)

Talman, R.

1989-04-01

81

Solar particle acceleration and propagation  

NASA Technical Reports Server (NTRS)

The research performed in the period 1983-1986 on solar-particle acceleration and propagation is discussed. Special attention is given to satellite-based observations of large solar energetic particles and (He-3)-rich events; measurements of solar gamma rays, neutrons, and low-energy (1-100-keV) electrons; and observations related to the interplanetary propagation of fast particles. Consideration is also given to theoretical acceleration models based on satellite measurements of accelerated ions.

Lin, R. P.

1987-01-01

82

High field gradient particle accelerator  

DOEpatents

A high electric field gradient electron accelerator utilizing short duration, microwave radiation, and capable of operating at high field gradients for high energy physics applications or at reduced electric field gradients for high average current intermediate energy accelerator applications is disclosed. Particles are accelerated in a smooth bore, periodic undulating waveguide, wherein the period is so selected that the particles slip an integral number of cycles of the r.f. wave every period of the structure. This phase step of the particles produces substantially continuous acceleration in a traveling wave without transverse magnetic or other guide means for the particle. 10 figs.

Nation, J.A.; Greenwald, S.

1989-05-30

83

High field gradient particle accelerator  

DOEpatents

A high electric field gradient electron accelerator utilizing short duration, microwave radiation, and capable of operating at high field gradients for high energy physics applications or at reduced electric field gradients for high average current intermediate energy accelerator applications. Particles are accelerated in a smooth bore, periodic undulating waveguide, wherein the period is so selected that the particles slip an integral number of cycles of the r.f. wave every period of the structure. This phase step of the particles produces substantially continuous acceleration in a traveling wave without transverse magnetic or other guide means for the particle.

Nation, John A. (Ithaca, NY) [Ithaca, NY; Greenwald, Shlomo (Haifa, IL) [Haifa, IL

1989-01-01

84

Particle accelerator for inducing contained particle collisions  

US Patent & Trademark Office Database

A particle accelerator for inducing contained particle collisions. The particle accelerator includes two hollow dees of electrically conductive material which are separated and electrically insulated from each other. The dees are located between the poles of a strong magnet which generates a magnetic field through top and bottom sides of the dees. In addition, the dees are connected to an oscillator for providing an alternating voltage between the dees. The dees are located within a chamber containing a gas and/or vapor provided at a measurable pressure. Ions are accelerated in essentially spiral paths within the dees, and follow paths which may be both concentric and non-concentric with the dees whereby collisions are produced between accelerated ions and gas or vapor atoms contained within the chamber, as well as between pairs of accelerated ions following different paths. The particle collisions within the chamber produces neutrons, generates energy, and performs other useful functions associated with the interaction of particles.

2002-08-27

85

Neutral particle beam intensity controller  

Microsoft Academic Search

A neutral beam intensity controller is provided for a neutral beam generator in which a neutral beam is established by accelerating ions from an ion source into a gas neutralizer. An amplitude modulated, rotating magnetic field is applied to the accelerated ion beam in the gas neutralizer to defocus the resultant neutral beam in a controlled manner to achieve intensity

Dagenhart; William K

1986-01-01

86

Dusty-Plasma Particle Accelerator  

NASA Technical Reports Server (NTRS)

A dusty-plasma apparatus is being investigated as means of accelerating nanometer- and micrometer-sized particles. Applications for the dusty-plasma particle accelerators fall into two classes: Simulation of a variety of rapidly moving dust particles and micrometeoroids in outer-space environments that include micrometeoroid streams, comet tails, planetary rings, and nebulae and Deposition or implantation of nanoparticles on substrates for diverse industrial purposes that could include hardening, increasing thermal insulation, altering optical properties, and/or increasing permittivities of substrate materials. Relative to prior apparatuses used for similar applications, dusty-plasma particle accelerators offer such potential advantages as smaller size, lower cost, less complexity, and increased particle flux densities. A dusty-plasma particle accelerator exploits the fact that an isolated particle immersed in plasma acquires a net electric charge that depends on the relative mobilities of electrons and ions. Typically, a particle that is immersed in a low-temperature, partially ionized gas, wherein the average kinetic energy of electrons exceeds that of ions, causes the particle to become negatively charged. The particle can then be accelerated by applying an appropriate electric field. A dusty-plasma particle accelerator (see figure) includes a plasma source such as a radio-frequency induction discharge apparatus containing (1) a shallow cup with a biasable electrode to hold the particles to be accelerated and (2) a holder for the substrate on which the particles are to impinge. Depending on the specific design, a pair of electrostatic-acceleration grids between the substrate and discharge plasma can be used to both collimate and further accelerate particles exiting the particle holder. Once exposed to the discharge plasma, the particles in the cup quickly acquire a negative charge. Application of a negative voltage pulse to the biasable electrode results in the initiation of a low-current, high-voltage cathode spot. Plasma pressure associated with the cathode spot as well as the large voltage drop at the cathode spot accelerates the charged particles toward the substrate. The ultimate kinetic energy attained by particles exiting the particle holder depends in part on the magnitude of the cathode spot sheath potential difference, which is proportional to the magnitude of the voltage pulse, and the on the electric charge on the dust. The magnitude of the voltage pulse can be controlled directly, whereas the particle s electric charge can be controlled indirectly by controlling the operating parameters of the plasma apparatus.

Foster, John E.

2005-01-01

87

Particle acceleration at planetary bow shock waves  

Microsoft Academic Search

One property of the collisionless shocks that may be studied through a comparison of their behavior in a variety of plasma conditions at several different planets is the occurrence of MHD waves, associated with particle beams accelerated at these shocks and flowing backward to the sun. Mercury, Venus, earth and Jupiter observations of one of these wave classes show that

M. M. Hoppe

1982-01-01

88

Recent progress in techniques utilized for particle accelerator  

NASA Astrophysics Data System (ADS)

Particle accelerators are widely used in scientific research and industry. Recently, techniques utilized for accelerator are developed rapidly in China. We briefly review the recent progress in this field and primarily focus on superconducting RF, innovative structures for particle production and acceleration and beam diagnosis. Several advanced compact user facilities are also introduced.

Liu, KeXin

2012-12-01

89

Space Experiments with Particle Accelerators: SEPAC  

NASA Technical Reports Server (NTRS)

The Space Experiments with Particle Accelerators (SEPAC), which flew on the Atmospheric Laboratory for Applications and Science (ATLAS) 1 mission, used new techniques to study natural phenomena in the Earth's upper atmosphere, ionosphere and magnetosphere by introducing energetic perturbations into the system from a high power electron beam with known characteristics. Properties of auroras were studied by directing the electron beam into the upper atmosphere while making measurements of optical emissions. Studies were also performed of the critical ionization velocity phenomenon.

Burch, J. L.; Roberts, W. T.; Taylor, W. W. L.; Kawashima, N.; Marshall, J. A.; Moses, S. L.; Neubert, T.; Mende, S. B.; Choueiri, E. Y.

1994-01-01

90

Safety training and safe operating procedures written for PBFA (Particle Beam Fusion Accelerator) II and applicable to other pulsed power facilities  

SciTech Connect

To ensure that work in advancing pulsed power technology is performed with an acceptably low risk, pulsed power research facilities at Sandia National Laboratories must satisfy general safety guidelines established by the Department of Energy, policies and formats of the Environment, Safety, and Health (ES and H) Department, and detailed procedures formulated by the Pulsed Power Sciences Directorate. The approach to safety training and to writing safe operating procedures, and the procedures presented here are specific to the Particle Beam Fusion Accelerator II (PBFA II) Facility but are applicable as guidelines to other research and development facilities which have similar hazards.

Donovan, G.L.; Goldstein, S.A.

1986-12-01

91

Space Experiments with Particle Accelerators (SEPAC)  

NASA Technical Reports Server (NTRS)

The purpose of Space Experiments with Particle Accelerators (SEPAC) on the Atmospheric Laboratory for Applications and Science (ATLAS 1) mission, is to carry out active and interactive experiments on and in the earth's ionosphere, atmosphere, and magnetosphere. The instruments to be used are an electron beam accelerator (EBA), plasma contactor, and associated instruments the purpose of which is to perform diagnostic, monitoring, and general data taking functions. Four major classes of investigations are to be performed by SEPAC. They are: beam plasma physics, beam-atmosphere interactions, the use of modulated electron beams as transmitting antennas, and the use of electron beams for remote sensing of electric and magnetic fields. The first class consists mainly of onboard plasma physics experiments to measure the effects of phenomena in the vicinity of the shuttle. The last three are concerned with remote effects and are supported by other ATLAS 1 investigations as well as by ground-based observations.

Obayashi, Tatsuzo

1988-01-01

92

Particle acceleration in pulsar magnetospheres  

NASA Technical Reports Server (NTRS)

The structure of pulsar magnetospheres and the acceleration mechanism for charged particles in the magnetosphere was studied using a pulsar model which required large acceleration of the particles near the surface of the star. A theorem was developed which showed that particle acceleration cannot be expected when the angle between the magnetic field lines and the rotation axis is constant (e.g. radial field lines). If this angle is not constant, however, acceleration must occur. The more realistic model of an axisymmetric neutron star with a strong dipole magnetic field aligned with the rotation axis was investigated. In this case, acceleration occurred at large distances from the surface of the star. The magnitude of the current can be determined using the model presented. In the case of nonaxisymmetric systems, the acceleration is expected to occur nearer to the surface of the star.

Baker, K. B.

1978-01-01

93

Investigation of Beam-RF Interactions in Twisted Waveguide Accelerating Structures Using Beam Tracking Codes  

SciTech Connect

Investigations of the RF properties of certain twisted waveguide structures show that they support favorable accelerating fields. This makes them potential candidates for accelerating cavities. Using the particle tracking code, ORBIT, We examine the beam - RF interaction in the twisted cavity structures to understand their beam transport and acceleration properties. The results will show the distinctive properties of these new structures for particle transport and acceleration, which have not been previously analyzed.

Holmes, Jeffrey A [ORNL] [ORNL; Zhang, Yan [ORNL] [ORNL; Kang, Yoon W [ORNL] [ORNL; Galambos, John D [ORNL] [ORNL; Hassan, Mohamed H [ORNL] [ORNL; Wilson, Joshua L [ORNL] [ORNL

2009-01-01

94

Particle beam injector system and method  

DOEpatents

Methods and devices enable coupling of a charged particle beam to a radio frequency quadrupole accelerator. Coupling of the charged particle beam is accomplished, at least in-part, by relying on of sensitivity of the input phase space acceptance of the radio frequency quadrupole to the angle of the input charged particle beam. A first electric field across a beam deflector deflects the particle beam at an angle that is beyond the acceptance angle of the radio frequency quadrupole. By momentarily reversing or reducing the established electric field, a narrow portion of the charged particle beam is deflected at an angle within the acceptance angle of the radio frequency quadrupole. In another configuration, beam is directed at an angle within the acceptance angle of the radio frequency quadrupole by the first electric field and is deflected beyond the acceptance angle of the radio frequency quadrupole due to the second electric field.

Guethlein, Gary

2013-06-18

95

Solving radiation problems at particle accelerators  

SciTech Connect

At high-intensity high-energy particle accelerators, consequences of a beam-induced radiation impact on machine and detector components, people, environment and complex performance can range from negligible to severe. The specifics, general approach and tools used at such machines for radiation analysis are described. In particular, the world leader Fermilab accelerator complex is considered, with its fixed target and collider experiments, as well as new challenging projects such as LHC, VLHC, muon collider and neutrino factory. The emphasis is on mitigation of deleterious beam-induced radiation effects and on the key role of effective computer simulations.

Nikolai V. Mokhov

2001-12-11

96

Design, modeling and simulations of a Cabinet Safe System for a linear particle accelerator of intermediate-low energy by optimization of the beam optics  

NASA Astrophysics Data System (ADS)

As part of an accelerator based Cargo Inspection System, studies were made to develop a Cabinet Safe System by Optimization of the Beam Optics of Microwave Linear Accelerators of the IAC-Varian series working on the S-band and standing wave pi/2 mode. Measurements, modeling and simulations of the main subsystems were done and a Multiple Solenoidal System was designed. This Cabinet Safe System based on a Multiple Solenoidal System minimizes the radiation field generated by the low efficiency of the microwave accelerators by optimizing the RF waveguide system and by also trapping secondaries generated in the accelerator head. These secondaries are generated mainly due to instabilities in the exit window region and particles backscattered from the target. The electron gun was also studied and software for its right mechanical design and for its optimization was developed as well. Besides the standard design method, an optimization of the injection process is accomplished by slightly modifying the gun configuration and by placing a solenoid on the waist position while avoiding threading the cathode with the magnetic flux generated. The Multiple Solenoidal System and the electron gun optimization are the backbone of a Cabinet Safe System that could be applied not only to the 25 MeV IAC-Varian microwave accelerators but, by extension, to machines of different manufacturers as well. Thus, they constitute the main topic of this dissertation.

Maidana, Carlos Omar

97

Particle shock acceleration in astrophysics  

NASA Astrophysics Data System (ADS)

The Fermi (diffusive) particle acceleration in astrophysical shocks is reviewed and evaluated. We discuss their properties and we present Monte Carlo simulations studying the shocks’ efficiency in accelerating particles (i.e. protons) up to very high energies with an application to astrophysical regions such as Supernovae, Active Galactic Nuclei hot spots and Gamma Ray Bursts. We find that the efficiency of the acceleration mechanism at shocks, varies in regard to the inclination of the magnetic field and the shock normal (e.g. sub-luminal shocks, super-luminal shocks), with consequences to the contribution of the very high energy particles to the observed cosmic ray spectrum.

Meli, Athina; Mastichiadis, Apostolos

2008-04-01

98

Applications of pyroelectric particle accelerators  

NASA Astrophysics Data System (ADS)

The discovery of pyroelectric X-ray generation in 1992 by Brownridge has led to a recent surge of interest in the use of the pyroelectric effect as a means of producing useful radiation. By heating or cooling a pyroelectric crystal such as lithium tantalate (LiTaO 3) in a vacuum, a potential on the order of 100 kV can be generated. This potential is great enough to eject electrons from the crystal for the production of characteristic or bremsstrahlung X-rays, or to cause field ionization near a tip mounted to the crystal. By using the combined fields of two polarized crystals, the acceleration potential can be doubled, with one crystal acting as a particle emitter and the other crystal serving as a target. Such a paired-crystal system was used to generate X-rays with energies of greater than 200 keV, and can be used to fluoresce the K shell of thorium ( Z = 92). An alternative use of pyroelectric sources is the field ionization of a dilute gas. If the positively-charged crystal is used to ionize a deuterium gas, and the target crystal is coated with deuterated target, the deuterium ions can be accelerated into the target at high enough energy to cause D-D fusion. Results verifying the production of D-D fusion neutrons from a pyroelectric source will be presented. Future applications of pyroelectric accelerator technology, such as the use of the electron beam for materials testing, will also be discussed.

Geuther, Jeffrey A.; Danon, Yaron

2007-08-01

99

Beam losses and beam halos in accelerators for new energy sources  

SciTech Connect

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

Jameson, R.A.

1995-12-31

100

Space Experiments with Particle Accelerators (SEPAC)  

NASA Technical Reports Server (NTRS)

The scientific emphasis of this contract has been on the physics of beam ionosphere interactions, in particular, what are the plasma wave levels stimulated by the Space Experiments with Particle Accelerators (SEPAC) electron beam as it is ejected from the Electron Beam Accelerator (EBA) and passes into and through the ionosphere. There were two different phenomena expected. The first was generation of plasma waves by the interaction of the DC component of the beam with the plasma of the ionosphere, by wave particle interactions. The second was the generation of waves at the pulsing frequency of the beam (AC component). This is referred to as using the beam as a virtual antenna, because the beam of electrons is a coherent electrical current confined to move along the earth's magnetic field. As in a physical antenna, a conductor at a radio or TV station, the beam virtual antenna radiates electromagnetic waves at the frequency of the current variations. These two phenomena were investigated during the period of this contract.

Taylor, William W. L.

1994-01-01

101

Acceleration of exp 14 C BEAMS in Electrostatic Accelerators.  

National Technical Information Service (NTIS)

Operational problems in the production and acceleration of exp 14 C beams for nuclear structure research in Los Alamos National Laboratory's Van de Graaff accelerators are discussed. Methods for the control of contamination in ion sources, accelerators an...

L. J. Rowton J. R. Tesmer

1981-01-01

102

Fundamentals of particle beam dynamics and phase space  

SciTech Connect

This report discusses the following topics on synchrotron accelerators: Transverse motion---betatron oscillations; machine lattice; representation of a particle beam; and longitudinal motion---synchrotron oscillations.

Weng, W.T.; Mane, S.R.

1991-09-04

103

A particle accelerator employing transient space charge potentials  

DOEpatents

The invention provides an accelerator for ions and charged particles. The plasma is generated and confined in a magnetic mirror field. The electrons of the plasma are heated to high temperatures. A series of local coils are placed along the axis of the magnetic mirror field. As an ion or particle beam is directed along the axis in sequence the coils are rapidly pulsed creating a space charge to accelerate and focus the beam of ions or charged particles. 3 figs.

Post, R.F.

1988-02-25

104

Applications of magnetized plasma to particle acceleration  

SciTech Connect

Magnetized plasma can be used as an accelerating structure capable of supporting large amplitude longitudinal fields which are externally driven by a high-frequency microwave source. Such structures can be used at very high frequencies (hundreds of gigahertz), placing them in the intermediate region between conventional (metallic) accelerators, and laser-driven plasma accelerators. They review two magnetic field configurations with respect to the direction of the particle beam propagation: (1) parallel magnetic field plus a helical undulator, and (2) perpendicular magnetic field. In the first configuration, plasma exhibits electromagnetically induced transparency (EIT) at the cyclotron frequency if the plasma frequency is equal to the electron cyclotron frequency. The second configuration corresponds to the inverse Cherenkov effect in magnetized plasma. In both cases, the group velocity of the accelerating plasma wave can be made very small, so that the incident electromagnetic wave is strongly compressed, resulting in the high accelerating gradient.

Shvets, Gennady; Wurtele, Jonathan S.; Hur, Min-Sup

2002-12-12

105

Computation applied to particle accelerator simulations  

SciTech Connect

The rapid growth in the power of large-scale computers has had a revolutionary effect on the study of charged-particle accelerators that is similar to the impact of smaller computers on everyday life. Before an accelerator is built, it is now the absolute rule to simulate every component and subsystem by computer to establish modes of operation and tolerances. We will bypass the important and fruitful areas of control and operation and consider only application to design and diagnostic interpretation. Applications of computers can be divided into separate categories including: component design, system design, stability studies, cost optimization, and operating condition simulation. For the purposes of this report, we will choose a few examples taken from the above categories to illustrate the methods and we will discuss the significance of the work to the project, and also briefly discuss the accelerator project itself. The examples that will be discussed are: (1) the tracking analysis done for the main ring of the Superconducting Supercollider, which contributed to the analysis which ultimately resulted in changing the dipole coil diameter to 5 cm from the earlier design for a 4-cm coil-diameter dipole magnet; (2) the design of accelerator structures for electron-positron linear colliders and circular colliding beam systems (B-factories); (3) simulation of the wake fields from multibunch electron beams for linear colliders; and (4) particle-in-cell simulation of space-charge dominated beams for an experimental liner induction accelerator for Heavy Ion Fusion. 8 refs., 9 figs.

Herrmannsfeldt, W.B. (Stanford Linear Accelerator Center, Menlo Park, CA (United States)); Yan, Y.T. (Superconducting Super Collider Lab., Dallas, TX (United States))

1991-07-01

106

Future Particle Accelerator Developments for Radiation Therapy  

NASA Astrophysics Data System (ADS)

During the last decade particle beam cancer therapy has seen a rapid increase in interest, and several new centers have been built, are currently under construction, or are in an advanced stage of planning. Typical treatment centers today consist of an accelerator capable of producing proton or ion beams in an energy range of interest for medical treatment, i.e. providing a penetration depth in water of about 30 cm, a beam delivery system to transport the produced beam to the patient treatment rooms, and several patient stations, allowing for an optimal usage of the continuously produced beam. This makes these centers rather large and consequently expensive. Only major hospital centers situated in an area where they can draw on a population of several million can afford such an installation. In order to spread the use of particle beam cancer therapy to a broader population base it will be necessary to scale down the facility size and cost. This can in principle be done by reducing the number of treatment rooms to one, eliminating the need of an elaborate beam delivery system, and thereby reducing the building size and cost. Such a change should be going in parallel with a reduction of the accelerator itself, and a number of approaches to this are currently being pursued. If successful, such developments could eventually lead to a compact system where all components would fit into a single shielded room, not much different in size from a typical radiation vault for radiotherapy with X-rays.

Holzscheiter, Michael H.; Bassler, Niels

107

Ionization front accelerator: high gradients, demonstrated particle acceleration, and a proposed relativistic accelerator  

SciTech Connect

The Ionization Front Accelerator (IFA) is a collective ion accelerator for which high-gradient particle acceleration has now been demonstrated. In the IFA, the space charge field at the front of an intense relativistic electron beam is controlled by a laser and used to accelerate an ion bunch. Two complete IFA systems have been built (IFA-1 and IFA-2). Here we present initial IFA-2 ion results that demonstrate that ions have been accelerated with controlled accelerating fields of 33 MV/m over 30 cm. Space charge fields of accelerators like the IFA and the plasma beat wave accelerator are compared, and both are shown to be capable of producing fields 1 GV/m and higher. The IFA systems are discussed and initial IFA-2 ion results are presented. Lastly, a relativistic IFA is proposed that should in principle, permit the attainment of virtually unlimited ion energies. 11 references, 8 figures.

Olson, C.L.; Frost, C.A.; Patterson, E.L.; Anthes, J.P.; Poukey, J.W.

1985-01-01

108

Soviet exoatmospheric neutral particle beam research  

SciTech Connect

This technical assessment was performed by a panel of eight U.S. scientists and engineers who are familiar with Soviet research through their own research experience, their knowledge of the published scientific literature and conference proceedings, and personal contacts with Soviet scientists and other foreign colleagues. Most of the technical components of a neutral particle beam generating system including the ion source, the accelerator, the accelerator radio frequency power supply, the beam conditioning and aiming system, and the beam neutralizer system are addressed. It does not address a number of other areas important to an exoatmospheric neutral beam system.

Leiss, J.E.; Abrams, R.H.; Ehlers, K.W.; Farrell, J.A.; Gillespie, G.H.; Jameson, R.A.; Keefe, D.; Parker, R.K.

1988-02-01

109

Neutral particle beam intensity controller  

Microsoft Academic Search

A method is proposed in which an amplitude-modulated, rotating magnetic field is applied to an accelerated ion beam in a gas neutralizer to defocus the resultant neutral and ion beam in a controlled manner to control the intensity of the neutral beam along the beam axis at constant beam energy. Adjustments in the gas pressure determine the fraction of ions

Dagenhart

1988-01-01

110

Neutral particle beam intensity controller  

Microsoft Academic Search

A method is proposed in which an amplitude-modulated, rotating magnetic field is applied to an accelerated ion beam in a gas neutralizer to defocus the resultant neutral and ion beam in a controlled manner to control the intensity of the neutral beam along the beam axis at constant beam energy. Adjustments in the gas pressure determine the fraction of ions

W. K. Dagenhart

1989-01-01

111

Particle Acceleration Mechanisms  

Microsoft Academic Search

In this paper we review the possible mechanisms for production of non-thermal electrons which are responsible for the observed\\u000a non-thermal radiation in clusters of galaxies. Our primary focus is on non-thermal Bremsstrahlung and inverse Compton scattering,\\u000a that produce hard X-ray emission. We first give a brief review of acceleration mechanisms and point out that in most astrophysical\\u000a situations, and in

V. Petrosian; A. M. Bykov

2008-01-01

112

Laser and Particle Guiding Micro-Elements for Particle Accelerators  

SciTech Connect

Laser driven particle accelerators require sub-micron control of the laser field as well as precise electron-beam guiding so fabrication techniques that allow integrating both elements into an accelerator-on-chip format become critical for the success of such next generation machines. Micromachining technology for silicon has been shown to be one such feasible technology in PAC2003[1] but with a variety of complications on the laser side. However, fabrication of transparent ceramics has become an interesting technology that could be applied for laser-particle accelerators in several ways. We discuss the advantages such as the range of materials available and ways to implement them followed by some different test examples we been considered. One important goal is an integrated system that avoids having to inject either laser or particle pulses into these structures.

Plettner, T.; Gaume, R.; Wisdom, J.; /Stanford U., Phys. Dept.; Spencer, J.; /SLAC

2005-06-07

113

FOCUSING AND ACCELERATION OF BUNCHED BEAMS  

SciTech Connect

A new approach to solving the kinetic equation for the beam distribution function, (very useful from the practical point of view), is discussed, in which the authors also obtain a complement to the Skrinsky's condition for the self-focused bunched beam. This problem belongs to the theory of nonlinear systems in which both regular and chaotic motion is possible. The kinetic approach, based on Vlasov-Poisson equations, are used to investigate the focusing and acceleration of bunched beam. Special attention is given to the studies of stability in a bunched beam by means of the two norm, which may be used to describe t!he motion of high-energy particles.

PARSA,Z.; ZADOROZHNY,V.

2000-04-07

114

Confined energy distribution for charged particle beams  

DOEpatents

A charged particle beam is formed to a relatively larger area beam which is well-contained and has a beam area which relatively uniformly deposits energy over a beam target. Linear optics receive an accelerator beam and output a first beam with a first waist defined by a relatively small size in a first dimension normal to a second dimension. Nonlinear optics, such as an octupole magnet, are located about the first waist and output a second beam having a phase-space distribution which folds the beam edges along the second dimension toward the beam core to develop a well-contained beam and a relatively uniform particle intensity across the beam core. The beam may then be expanded along the second dimension to form the uniform ribbon beam at a selected distance from the nonlinear optics. Alternately, the beam may be passed through a second set of nonlinear optics to fold the beam edges in the first dimension. The beam may then be uniformly expanded along the first and second dimensions to form a well-contained, two-dimensional beam for illuminating a two-dimensional target with a relatively uniform energy deposition.

Jason, Andrew J. (Los Alamos, NM); Blind, Barbara (Los Alamos, NM)

1990-01-01

115

Neutral Particle Beam Popup Applications.  

National Technical Information Service (NTIS)

Popup neutral particle beams (NPBs) could have high leverage in discriminating decoyed threats. There is considerable leeway in the choice of platform parameters. For deuterium beams the number of platforms is modest for all energies. Hydrogen beams might...

G. H. Canavan

1991-01-01

116

Space experiments with particle accelerators. [Spacelab  

NASA Technical Reports Server (NTRS)

The purpose of space experiments with particle accelerators (SEPAC) is to carry out active and interactive experiments on and in the Earth's ionosphere and magnetosphere. It is also intended to make an initial performance test for an overall program of Spacelab/SEPAC experiments. The instruments to be used are an electron beam accelerator, magnetoplasma dynamic arcjet, and associated diagnostic equipment. The accelerators are installed on the pallet, with monitoring and diagnostic observations being made by the gas plume release, beam-monitor TV, and particle-wave measuring instruments also mounted on the pallet. Command and display systems are installed in the module. Three major classes of investigations to be performed are vehicle charge neutralization, beam plasma physics, and beam atmosphere interactions. The first two are mainly onboard plasma physics experiments to measure the effect of phenomena in the vicinity of Spacelab. The last one is concerned with atmospheric modification and is supported by other Spacelab 1 investigations as well as by ground-based, remote sensing observations.

Obayashi, T.

1981-01-01

117

Proceedings of the 2003 Particle Accelerator Conference  

SciTech Connect

The twentieth biennial Particle Accelerator Conference on Accelerator Science and Technology was held May 12 ? 16, 2003 at the Hilton Hotel in Portland, Oregon. The Stanford Linear Accelerator Center and the Lawrence Berkeley National Laboratory organized PAC 2003, and it was held under the auspices of the Nuclear and Plasma Sciences Society of the Institute of Electrical and Electronics Engineers and the Division of Physics of Beams of the American Physical Society. The attendance was 1025 registrants from 21 countries. The Program Committee was co-chaired by Alan Jackson and Ed Lee. The program they arranged had opening and closing plenary sessions that covered the most important accomplishments, opportunities, and applications of accelerators. During the remainder of the conference there were parallel sessions with oral and poster presentations. In addition, there was an industrial exhibit during the first three days. The Proceedings present a total of 1154 papers from the invited, contributed orals, and poster sessions.

various,

2004-03-01

118

A Fundamental Theorem on Particle Acceleration  

SciTech Connect

A fundamental theorem on particle acceleration is derived from the reciprocity principle of electromagnetism and a rigorous proof of the theorem is presented. The theorem establishes a relation between acceleration and radiation, which is particularly useful for insightful understanding of and practical calculation about the first order acceleration in which energy gain of the accelerated particle is linearly proportional to the accelerating field.

Xie, Ming

2003-05-01

119

Naked singularities as particle accelerators  

SciTech Connect

We investigate here the particle acceleration by naked singularities to arbitrarily high center of mass energies. Recently it has been suggested that black holes could be used as particle accelerators to probe the Planck scale physics. We show that the naked singularities serve the same purpose and probably would do better than their black hole counterparts. We focus on the scenario of a self-similar gravitational collapse starting from a regular initial data, leading to the formation of a globally naked singularity. It is seen that when particles moving along timelike geodesics interact and collide near the Cauchy horizon, the energy of collision in the center of mass frame will be arbitrarily high, thus offering a window to Planck scale physics.

Patil, Mandar; Joshi, Pankaj S. [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India)

2010-11-15

120

Accelerating light beams along arbitrary convex trajectories.  

PubMed

We demonstrate, theoretically and experimentally, nonbroadening optical beams propagating along any arbitrarily chosen convex trajectory in space. We present a general method to construct such beams, and demonstrate it by generating beams following polynomial and exponential trajectories. We find that all such beams, accelerating along any convex trajectory, display the same universal intensity cross section, irrespective of their acceleration. The universal features of these beams are explored using catastrophe theory. PMID:21699298

Greenfield, Elad; Segev, Mordechai; Walasik, Wiktor; Raz, Oren

2011-05-27

121

Power Oscillator Circuit Modeling and Redesign for the Particle Beam Fusion Accelerator II (PBFA-II) Switch Trigger Laser.  

National Technical Information Service (NTIS)

The energy output and reliability of the multi-joule, injection-locked KrF laser used to trigger the PBFA II accelerator gas switches were improved through modifications identified in modeling the Blumlein driver circuit for the power oscillator. A combin...

D. L. Smith R. A. Hamil K. R. Prestwich G. J. Rohwein G. L. Donovan

1987-01-01

122

Influence of proton beam Coulomb explosion in laser proton acceleration  

NASA Astrophysics Data System (ADS)

To further understand proton acceleration driven by the interaction between ultra-intense laser pulse and foil targets, the influence of proton beam Coulomb explosion has been analyzed theoretically and investigated using two-dimensional particle-in-cell (2D-PIC) simulations. Employing different proton layer sizes in the simulations, it is found that proton beam Coulomb explosion plays an important role on proton acceleration, in particular on proton cut off energy. Proton dynamics including the effect of both sheath field and proton beam Coulomb explosion was proposed and discussed in detail. This work may serve to improve the understanding of proton acceleration driven by intense laser-foil interactions.

Yu, Jinqing; Jin, Xiaolin; Zhou, Weimin; Gu, Yuqiu; Zhan, Rongxin; Zhao, Zongqing; Cao, Leifeng; Li, Bin

2013-12-01

123

Laser-and Beam-Driven Plasma Accelerators  

NASA Astrophysics Data System (ADS)

Scientists have been trying to use the tremendous electric fields in relativistic plasma waves to accelerate charged particles, and are now making substantial progress. If they succeed, future high energy accelerators will use plasma waves rather than microwave cavities as accelerating structures.Some accelerators, such as those used for radiation therapy will fit on a tabletop. Research on using plasma waves to accelerate particles began in earnest following the suggestion by John Dawson and his colleagues [1-3] that a relativistically propagating plasma wave or a wake field could be excited by using a powerful but short laser -or electron -beam as a driver pulse.Since their original suggestion the research on plasma --based accelerators has spread worldwide A series of experiments by the UCLA/USC/SLAC collaboration ,using the 30 GeV beam of the Stanford Linear Accelerator Center (SLAC), has demonstrated high-gradient acceleration of electrons and positrons using the the wake left by the SLAC beam as it passes through a lithium plasma. Electrons have been accelerated by more than 30 GeV in less than one meter. This acceleration gradient is about a thousand times larger than in conventional microwave-driven accelerators. It is a first step toward a ``plasma afterburner,'' which would be placed at the end of a kilometers-long conventional accelerator and double its beam energy in a few tens of meters. In addition to the acceleration of particle beams, these experiments have demonstrated the rich physics bounty to be reaped from relativistic beam-plasma interactions. This includes the generation of intense and narrowly collimated x-ray beams, refraction of particles at a plasma interface, and the creation of intense beams of positrons. These results are leading the way to similar tabletop accelerators based on plasma wakes excited by lasers rather than electron beams. Applications for tabletop accelerators include gamma radiography, radiation therapy, and ultra-fast materials science. [1] T.Tajima and J.M.Dawson Phys.Rev.Lett. 43,267.(1979) [2] P.Chen et.al. Phys.Rev.Lett.54,693,(1985) [3]C.Joshi et.al. Nature 311,525,(1984) In collaboration with all my past and present students and co-workers and in particular collaborators on E157,162,164 and 167 experiments at SLAC.

Joshi, Chandrashekhar

2006-10-01

124

Neutral Particle Beam Intensity Controller.  

National Technical Information Service (NTIS)

A method is proposed in which an amplitude-modulated, rotating magnetic field is applied to an accelerated ion beam in a gas neutralizer to defocus the resultant neutral and ion beam in a controlled manner to control the intensity of the neutral beam alon...

W. K. Dagenhart

1988-01-01

125

TIARA electrostatic accelerators for multiple ion beam application  

NASA Astrophysics Data System (ADS)

A unique electrostatic accelerators facility has been constructed mainly for application of multiple beam and microbeam to materials science research at JAERI Takasaki. The facility consists of a 3 MV single-ended accelerator with an extremely high voltage-stability of ± 1 × 10 -5, a 3 MV tandem accelerator and a 0.4 MV ion implanter, which cover various ion particles in an energy range of 10 keV to 20 MeV. A voltage ripple of ± 1 × 10 -5 (60 Vpp) at 3 MV has been achieved for the single-ended machine. The performance of accelerators, beam lines and their applications to various research activities are outlined.

Saitoh, Y.; Tajima, S.; Takada, I.; Mizuhashi, K.; Uno, S.; Ohkoshi, K.; Ishii, Y.; Kamiya, T.; Yotumoto, K.; Tanaka, R.; Iwamoto, E.

1994-05-01

126

Neutral Particle Beam Distributed Data Acquisition System.  

National Technical Information Service (NTIS)

A distributed data acquisition system has been designed to support experiments at the Argonne Neutral Particle Beam Accelerator. The system uses a host VAXstation II/GPX computer acting as an experimenter's station linked via Ethernet with multiple MicroV...

R. T. Daly M. R. Kraimer A. H. Novick

1987-01-01

127

Generation of single pulse particle beams in a plasma channel by laser injection in laser wakefield accelerators  

Microsoft Academic Search

A laser injection mechanism that generates a single pulse, high quality beam is described. In the past, different all-optical injection schemes for the generation of ultrashort electron bunches were proposed. A very promising scheme proposed by E. Esarey [E. Esarey, R.F. Hubbard, W.P. Leemans A. Ting and P. Sprangle,\\

R. E. Giacone; J. R. Cary; Chet Nieter; E. Esarey; W. Leemans; G. Fubiani; C. Schroeder

2003-01-01

128

Tidal acceleration of ultrarelativistic particles  

NASA Astrophysics Data System (ADS)

We investigate the motion of free relativistic particles relative to the ambient medium around a gravitationally collapsed system. If the relative speed exceeds a critical value given by c/?{2}, the gravitational tidal effects exhibit novel features that are contrary to Newtonian expectations. In particular, ultrarelativistic jet clumps moving freely outward along the rotation axis strongly decelerate with respect to the ambient medium, while ultrarelativistic particles strongly accelerate in directions normal to the jet axis. The implications of these direct consequences of general relativity for jets in microquasars and the origin of the high-energy cosmic rays are briefly mentioned.

Chicone, C.; Mashhoon, B.

2005-07-01

129

Fast ion mass spectrometry and charged particle spectrography investigations of transverse ion acceleration and beam-plasma interactions  

NASA Technical Reports Server (NTRS)

Ion acceleration transverse to the magnetic field in the topside ionosphere was investigated. Transverse acceleration is believed to be responsible for the upward-moving conical ion distributions commonly observed along auroral field lines at altitudes from several hundred to several thousand kilometers. Of primary concern in this investigation is the extent of these conic events in space and time. Theoretical predictions indicate very rapid initial heating rates, depending on the ion species. These same theories predict that the events will occur within a narrow vertical region of only a few hundred kilometers. Thus an instrument with very high spatial and temporal resolution was required; further, since different heating rates were predicted for different ions, it was necessary to obtain composition as well as velocity space distributions. The fast ion mass spectrometer (FIMS) was designed to meet these criteria. This instrument and its operation is discussed.

Gibson, W. C.; Tomlinson, W. M.; Marshall, J. A.

1987-01-01

130

Application of charged particle beams of TWAC-ITEP accelerator for diagnostics of high dynamic pressure processes  

Microsoft Academic Search

The 800 MeV proton radiography facility for high dynamic pressure research in condensed matter has been commissioned at the Terrawatt Accelerator of Institute of Theoretical and Experimental Physics (TWAC-ITEP) in Moscow. Spatial resolution of the facility measured in static experiments with a variety of test objects was found to be 0.30±0.01 mm in current experimental arrangement. First dynamic experiments on the observation

S. A. Kolesnikov; A. A. Golubev; V. S. Demidov; S. V. Dudin; A. V. Kantsyrev; V. B. Mintsev; G. N. Smirnov; V. I. Turtikov; A. V. Utkin; B. Y. Sharkov; V. E. Fortov

2010-01-01

131

Neutral particle beam intensity controller  

DOEpatents

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

Dagenhart, W.K.

1984-05-29

132

Space Experiments with Particle Accelerators (SEPAC)  

NASA Technical Reports Server (NTRS)

Plans for SEPAC, an instrument array to be used on Spacelab 1 to study vehicle charging and neutralization, beam-plasma interaction in space, beam-atmospheric interaction exciting artificial aurora and airglow, and the electromagnetic-field configuration of the magnetosphere, are presented. The hardware, consisting of electron beam accelerator, magnetoplasma arcjet, neutral-gas plume generator, power supply, diagnostic package (photometer, plasma probes, particle analyzers, and plasma-wave package), TV monitor, and control and data-management unit, is described. The individual SEPAC experiments, the typical operational sequence, and the general outline of the SEPAC follow-on mission are discussed. Some of the experiments are to be joint ventures with AEPI (INS 003) and will be monitored by low-light-level TV.

Obayashi, T.; Kawashima, N.; Kuriki, K.; Nagatomo, M.; Ninomiya, K.; Sasaki, S.; Ushirokawa, A.; Kudo, I.; Ejiri, M.; Roberts, W. T.

1982-01-01

133

Semiclassical geons at particle accelerators  

NASA Astrophysics Data System (ADS)

We point out that in certain four-dimensional extensions of general relativity constructed within the Palatini formalism stable self-gravitating objects with a discrete mass and charge spectrum may exist. The incorporation of nonlinearities in the electromagnetic field may effectively reduce their mass spectrum by many orders of magnitude. As a consequence, these objects could be within (or near) the reach of current particle accelerators. We provide an exactly solvable model to support this idea.

Olmo, Gonzalo J.; Rubiera-Garcia, D.

2014-02-01

134

Electron beam accelerator with magnetic pulse compression and accelerator switching  

DOEpatents

An electron beam accelerator comprising an electron beam generator-injector to produce a focused beam of .gtoreq.0.1 MeV energy electrons; a plurality of substantially identical, aligned accelerator modules to sequentially receive and increase the kinetic energies of the beam electrons by about 0.1-1 MeV per module. Each accelerator module includes a pulse-forming network that delivers a voltage pulse to the module of substantially 0.1-1 MeV maximum energy over a time duration of .ltoreq.1 .mu.sec.

Birx, Daniel L. (Brentwood, CA); Reginato, Louis L. (Orinda, CA)

1987-01-01

135

Electron beam accelerator with magnetic pulse compression and accelerator switching  

DOEpatents

An electron beam accelerator comprising an electron beam generator-injector to produce a focused beam of .gtoreq.0.1 MeV energy electrons; a plurality of substantially identical, aligned accelerator modules to sequentially receive and increase the kinetic energies of the beam electrons by about 0.1-1 MeV per module. Each accelerator module includes a pulse-forming network that delivers a voltage pulse to the module of substantially .gtoreq.0.1-1 MeV maximum energy over a time duration of .ltoreq.1 .mu.sec.

Birx, Daniel L. (Brentwood, CA); Reginato, Louis L. (Orinda, CA)

1988-01-01

136

Electron beam accelerator with magnetic pulse compression and accelerator switching  

DOEpatents

An electron beam accelerator is described comprising an electron beam generator-injector to produce a focused beam of greater than or equal to .1 MeV energy electrons; a plurality of substantially identical, aligned accelerator modules to sequentially receive and increase the kinetic energies of the beam electron by about .1-1 MeV per module. Each accelerator module includes a pulse-forming network that delivers a voltage pulse to the module of substantially .1-1 MeV maximum energy over a time duration of less than or equal to 1 ..mu..sec.

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

1984-03-22

137

Negative ion beam acceleration and transport experiments  

NASA Astrophysics Data System (ADS)

The design of a negative ion beam transport system is discussed. The ion source and accelerator have produced a 1-A, 8 keV beam of Hions with a pulse length of 30 seconds. The beam was additionally characterized as to electron content, uniformity along the slot, emittance perpendicular to the slot, and the beam divergence.

Cooper, W. S.; Anderson, O. A.; Kwan, J.; Steele, W. F.

1985-11-01

138

Resonance, particle dynamics, and particle transmission in the micro-accelerator platform  

NASA Astrophysics Data System (ADS)

We describe particle dynamics in the Micro-Accelerator Platform (MAP), a slab-symmetric dielectric laser accelerator (DLA), and model the expected performance of recently fabricated MAP structures. The quality of the structure resonances has been characterized optically, and results are compared with simulation. 3D trajectory analysis is used to model acceleration in those same structures ``as built.'' Results are applied to ongoing beam transmission and acceleration tests at NLCTA/E-163, in which transmission of 60 MeV injected electrons through the beam channel of the MAP was clearly observed, despite the overfilling of the structure by the beam.

McNeur, J.; Hazra, K. S.; Liu, G.; Sozer, E. B.; Travish, G.; Yoder, R. B.

2012-12-01

139

Physics and Application of Intense Charged Particle Beams 3. Intense Charged Particle Beams Using Pulse Power Systems  

NASA Astrophysics Data System (ADS)

Intense particle beams driven by pulse power generators, are basically high current and low energy. A strong coupling between the high current beams and the electromagnetic field not only degrades the beam quality in the acceleration gap but also makes difficult to transport them. Although indactive acceleration poses many problems, which remain unsolved, it seems to be an effective way to avoid this interaction. In this report, characteristics of pulse powered beams are reviewed and issues regarding them are briefly discussed.

Horioka, Kazuhiko

140

RFQ device for accelerating particles  

DOEpatents

A superconducting radio frequency quadrupole (RFQ) device includes four spaced elongated, linear, tubular rods disposed parallel to a charged particle beam axis, with each rod supported by two spaced tubular posts oriented radially with respect to the beam axis. The rod and post geometry of the device has four-fold rotation symmetry, lowers the frequency of the quadrupole mode below that of the dipole mode, and provides large dipole-quadrupole mode isolation to accommodate a range of mechanical tolerances. The simplicity of the geometry of the structure, which can be formed by joining eight simple T-sections, provides a high degree of mechanical stability, is insensitive to mechanical displacement, and is particularly adapted for fabrication with superconducting materials such as niobium. 5 figs.

Shepard, K.W.; Delayen, J.R.

1995-06-06

141

RFQ device for accelerating particles  

DOEpatents

A superconducting radio frequency quadrupole (RFQ) device includes four spaced elongated, linear, tubular rods disposed parallel to a charged particle beam axis, with each rod supported by two spaced tubular posts oriented radially with respect to the beam axis. The rod and post geometry of the device has four-fold rotation symmetry, lowers the frequency of the quadrupole mode below that of the dipole mode, and provides large dipole-quadrupole mode isolation to accommodate a range of mechanical tolerances. The simplicity of the geometry of the structure, which can be formed by joining eight simple T-sections, provides a high degree of mechanical stability, is insensitive to mechanical displacement, and is particularly adapted for fabrication with superconducting materials such as niobium.

Shepard, Kenneth W. (Park Ridge, IL); Delayen, Jean R. (Naperville, IL)

1995-01-01

142

Conditional Fluid-Particle Accelerations in Turbulence  

Microsoft Academic Search

.   Simple closures for average fluid-particle accelerations, conditional on fixed local fluid velocity, are considered in isotropic,\\u000a homogeneous and stationary turbulence using exact probability density transport equations and are compared with direct numerical\\u000a simulations (DNS). Such accelerations are common ingredients in Lagrangian stochastic models for fluid-particle trajectories\\u000a in turbulence. One-particle accelerations are essentially trivial, so the focus is on two-particle

M. S. Borgas; P. K. Yeung

1998-01-01

143

Use of particle beams for lunar prospecting  

NASA Technical Reports Server (NTRS)

A key issue in choosing the appropriate site for a manned lunar base is the availability of resources, particularly oxygen and hydrogen for the production of water, and ores for the production of fuels and building materials. NASA has proposed two Lunar Scout missions that would orbit the Moon and use, among other instruments, a hard X-ray spectrometer, a neutron spectrometer, and a Ge gamma ray spectrometer to map the lunar surface. This passive instrumentation will have low resolution (tens of kilometers) due to the low signal levels produced by natural radioactivity and the interaction of cosmic rays and the solar wind with the lunar surface. This paper presents the results of a concept definition effort for a neutral particle beam lunar mapper probe. The idea of using particle beam probes to survey asteroids was first proposed by Sagdeev et al., and an ion beam device was fielded on the 1988 Soviet probe to the Mars moon Phobos. During the past five years, significant advances in the technology of neutral particle beams (NPB) have led to a suborbital flight of a neutral hydrogen beam device in the SDIO-sponsored BEAR experiment. An orbital experiment, the Neutral Particle Beam Far Field Optics Experiment (NPB-FOX) is presently in the preliminary design phase. The development of NPB accelerators that are space-operable leads one to consider the utility of these devices for probing the surface of the Moon using gamma ray, X-ray, and optical/UV spectroscopy to locate various elements and compounds. We consider the utility of the NPB-FOX satellite containing a 5-MeV particle beam accelerator as a probe in lunar orbit. Irradiation of the lunar surface by the particle beam will induce secondary and back scattered radiation from the lunar surface to be detected by a sensor that may be co-orbital with or on the particle beam satellite platform, or may be in a separate orbit. The secondary radiation is characteristic of the make-up of the lunar surface. The size of the spot irradiated by the beam is less than 1 km wide along the ground track of the satellite, resulting in the potential for high resolution. The fact that the probe could be placed in polar orbit would result in global coverage of the lunar surface. The orbital particle beam probe could provide the basis for selection of sites for more detailed prospecting by surface rovers.

Toepfer, A. J.; Eppler, D.; Friedlander, A.; Weitz, R.

1993-01-01

144

Plasma based charged-particle accelerators  

Microsoft Academic Search

Studies of charged-particle acceleration processes remain one of the most important areas of research in laboratory, space and astrophysical plasmas. In this paper, we present the underlying physics and the present status of high gradient and high energy plasma accelerators. We will focus on the acceleration of charged particles to relativistic energies by plasma waves that are created by intense

R Bingham; J T Mendonça; P K Shukla

2004-01-01

145

The LICPA accelerator of dense plasma and ion beams  

NASA Astrophysics Data System (ADS)

Laser-induced cavity pressure acceleration (LICPA) is a novel scheme of acceleration of dense matter having a potential to accelerate plasma projectiles with the energetic efficiency much higher than the achieved so far with other methods. In this scheme, a projectile placed in a cavity is irradiated by a laser beam introduced into the cavity through a hole and accelerated along a guiding channel by the thermal pressure created in the cavity by the laser-produced plasma or by the photon pressure of the ultraintense laser radiation trapped in the cavity. This paper summarizes briefly the main results of our recent LICPA studies, in particular, experimental investigations of ion beam generation and heavy macroparticle acceleration in the hydrodynamic LICPA regime (at moderate laser intensities ~ 1015W/cm2) and numerical, particle-in-cell (PIC) studies of production of ultraintense ion beams and fast macroparticles using the photon pressure LICPA regime (at high laser intensities > 1020 W/cm2). It is shown that in both LICPA regimes the macroparticles and ion beams can be accelerated much more efficiently than in other laser-based acceleration scheme commonly used and the accelerated plasma/ion bunches can have a wide variety of parameters. It creates a prospect for a broad range of applications of the LICPA accelerator, in particular in such domains as high energy density physics, ICF research (ion fast ignition, impact ignition) or nuclear physics.

Badziak, J.; Jablo?ski, S.; Pisarczyk, T.; Chodukowski, T.; Parys, P.; Raczka, P.; Rosi?ski, M.; Krousky, E.; Ullschmied, J.; Liska, R.; Kucharik, M.; Torrisi, L.

2014-04-01

146

Nonlinear waves on charged particle beams  

NASA Astrophysics Data System (ADS)

A two dimensional particle simulation of the resistive filamentation instability on a charge and current neutralized particle beam was performed. The nonlinear development of the instability is analyzed with reference to the focusing requirements of heavy ion beams acting as drivers for pellet fusion. It is found that magnetically pinched current filaments form for all values of the dimensionless parameter. The combined area of the filaments decreases significantly as the filaments coalesce. This leads to a speculation that adequate focusing of the beam may be possible in spite of the development of this instability. Nonlinear space-charge waves in a strongly magnetized cylindrical plasma were also investigated. Soliton and periodic wave solutions were obtained. For the case of an intense unneutralized electron beam, a significant decrease in the phase velocity of the slow spce charge wave is found at large amplitudes. The importance of this result for some collective ion acceleration schemes is discussed.

Hughes, T. P.

147

Acceleration and stability of a high-current ion beam in induction fields  

SciTech Connect

A one-dimensional nonlinear analytic theory of the filamentation instability of a high-current ion beam is formulated. The results of 2.5-dimensional numerical particle-in-cell simulations of acceleration and stability of an annular compensated ion beam (CIB) in a linear induction particle accelerator are presented. It is shown that additional transverse injection of electron beams in magnetically insulated gaps (cusps) improves the quality of the ion-beam distribution function and provides uniform beam acceleration along the accelerator. The CIB filamentation instability in both the presence and the absence of an external magnetic field is considered.

Karas', V. I.; Manuilenko, O. V. [National Science Center Kharkov Institute of Physics and Technology (Ukraine)] [National Science Center Kharkov Institute of Physics and Technology (Ukraine); Tarakanov, V. P. [Russian Academy of Sciences, Joint Institute for High Temperature (Russian Federation)] [Russian Academy of Sciences, Joint Institute for High Temperature (Russian Federation); Federovskaya, O. V. [National Science Center Kharkov Institute of Physics and Technology (Ukraine)] [National Science Center Kharkov Institute of Physics and Technology (Ukraine)

2013-03-15

148

How to obtain particles to accelerate  

NSDL National Science Digital Library

Where do the particles come from that are accelerated in a particle accelerator? In this portion of a particle physics tutorial, three sources of particles are described for students. The first source is electrons, which come from heated metals. The second is protons, which are available from ionized hydrogen. Antiparticles are the third source. They are collected by magnetic fields after particles smash targets. Copyright 2005 Eisenhower National Clearinghouse

Group, Lawrence B.

2002-01-01

149

Frontiers of particle beam physics  

SciTech Connect

First, a review is given of various highly-developed techniques for particle handling which are, nevertheless, being vigorously advanced at the present time. These include soft superconductor radio frequency cavities, hard superconductor magnets, cooling rings for ions and anti-protons, and damping rings for electrons. Second, attention is focused upon novel devices for particle generation, acceleration, and focusing. These include relativistic klystrons and free electron laser power sources, binary power multipliers, photocathodes, switched-power linacs, plasma beat-wave accelerators, plasma wake-field accelerators, plasma lenses, plasma adiabatic focusers and plasma compensators. 12 refs.

Sessler, A.M.

1989-11-01

150

Magnetic Control of Particle Injection in Plasma Based Accelerators  

SciTech Connect

The use of an external transverse magnetic field to trigger and to control electron self-injection in laser- and particle-beam driven wakefield accelerators is examined analytically and through full-scale particle-in-cell simulations. A magnetic field can relax the injection threshold and can be used to control main output beam features such as charge, energy, and transverse dynamics in the ion channel associated with the plasma blowout. It is shown that this mechanism could be studied using state-of-the-art magnetic fields in next generation plasma accelerator experiments.

Vieira, J.; Martins, S. F.; Pathak, V. B.; Silva, L. O. [GoLP/Instituto de Plasmas e Fusao Nuclear-Laboratorio Associado, Instituto Superior Tecnico, 1049-001 Lisboa (Portugal); Fonseca, R. A. [GoLP/Instituto de Plasmas e Fusao Nuclear-Laboratorio Associado, Instituto Superior Tecnico, 1049-001 Lisboa (Portugal); DCTI/ISCTE Lisbon University Institute, 1649-026 Lisbon (Portugal); Mori, W. B. [Department of Physics and Astronomy, UCLA, Los Angeles, California 90095 (United States)

2011-06-03

151

The Los Alamos Laser Acceleration of Particles Workshop and beginning of the advanced accelerator concepts field  

NASA Astrophysics Data System (ADS)

The first Advanced Acceleration of Particles-AAC-Workshop (actually named Laser Acceleration of Particles Workshop) was held at Los Alamos in January 1982. The workshop lasted a week and divided all the acceleration techniques into four categories: near field, far field, media, and vacuum. Basic theorems of particle acceleration were postulated (later proven) and specific experiments based on the four categories were formulated. This landmark workshop led to the formation of the advanced accelerator R&D program in the HEP office of the DOE that supports advanced accelerator research to this day. Two major new user facilities at Argonne and Brookhaven and several more directed experimental efforts were built to explore the advanced particle acceleration schemes. It is not an exaggeration to say that the intellectual breadth and excitement provided by the many groups who entered this new field provided the needed vitality to then recently formed APS Division of Beams and the new online journal Physical Review Special Topics-Accelerators and Beams. On this 30th anniversary of the AAC Workshops, it is worthwhile to look back at the legacy of the first Workshop at Los Alamos and the fine groundwork it laid for the field of advanced accelerator concepts that continues to flourish to this day.

Joshi, C.

2012-12-01

152

Neutral particle beam distributed data acquisition system  

SciTech Connect

A distributed data acquisition system has been designed to support experiments at the Argonne Neutral Particle Beam Accelerator. The system uses a host VAXstation II/GPX computer acting as an experimenter's station linked via Ethernet with multiple MicroVAX IIs and rtVAXs dedicated to acquiring data and controlling hardware at remote sites. This paper describes the hardware design of the system, the applications support software on the host and target computers, and the real-time performance.

Daly, R.T.; Kraimer, M.R.; Novick, A.H.

1987-08-01

153

Neutral particle beam distributed data acquisition system  

SciTech Connect

A distributed data acquisition system has been designed to support experiments at the Argonne Neutral Particle Beam Accelerator. The system uses a host VAXstation II/GPX computer acting as an experimenter's station linked via Ethernet with multiple MicroVAX IIs and rtVAXs dedicated to acquiring data and controlling hardware at remote sites. This paper describes the hardware design of the system, the applications support software on the host and target computers, and the real-time performance.

Daly, R.T.; Kraimer, M.R.; Novick, A.H.

1987-01-01

154

Neutral particle beam distributed data acquisition system  

Microsoft Academic Search

A distributed data acquisition system has been designed to support experiments at the Argonne Neutral Particle Beam Accelerator. The system uses a host VAXstation II\\/GPX computer acting as an experimenter's station linked via Ethernet with multiple MicroVAX IIs and rtVAXs dedicated to acquiring data and controlling hardware at remote sites. This paper describes the hardware design of the system, the

R. T. Daly; M. R. Kraimer; A. H. Novick

1987-01-01

155

High Quality Electron Beams from Laser Accelerators  

NASA Astrophysics Data System (ADS)

Twenty five years ago, laser driven accelerators were proposed as an alternative to conventional accelerator systems.[1] The appeal was and is the large accelerating gradients (up to hundreds of GV/m) that can allow the development of compact devices capable of producing multi-GeV electron beams. Until recently, all experiments produced large gradients but beams with 100 % energy spread and only a small amount of electrons at high energy. This has recently changed. At the multi-beam L'OASIS facility at LBNL we have produced beams with narrow energy spread using a channel guided laser accelerator.[2] At Rutherford Appleton Laboratories (UK)[3] and at the Ecole Polytechnique (France),[4] beams with narrow energy spread were produced by using laser beams with relatively large focal spots. These results demonstrate that laser-plasma based accelerator can produce high quality electron beams. A review of the L'OASIS experiments will be presented as well as our plans and activities for producing a GeV-class electron beam. [1] T. Tajima and J.M. Dawson, Phys. Rev. Lett. 43, 267-270 (1979). [2] C.G.R. Geddes et al., Nature 431, 538- 541(2004). [3] S.P.D. Mangles et al., Nature 431, 535 --538 (2004). [4] J. Faure et al., Nature 431, 541-544 (2004).

Leemans, Wim

2005-04-01

156

Report on the Possible Benefits of Using High-Temperature Superconductor Materials in Particle Accelerator Design.  

National Technical Information Service (NTIS)

This report discusses different design concepts for particle beam accelerators. It demonstrates that with the use of high temperature superconducting materials, a more compact, lighter, and more robust accelerator design can be realized for the space base...

B. Balko L. Cohen R. Collins

1988-01-01

157

Pointing of laser-accelerated proton beams  

SciTech Connect

Small fluctuations in the acceleration sheath change the pointing of a proton beam accelerated from the rear side of a laser irradiated thin aluminum foil. The proton acceleration was produced with 40 fs pulses of a Ti:sapphire laser at an intensity of approximately 10{sup 19} W/cm{sup 2}. This observation has been made with a high spatial resolution Thomson spectrometer. The proton beam pointing has appeared stable in the energy range between the high energy cutoff (3 MeV) and 50% of this value. Deviations of the beam position at lower energies changes in a range of 0-3 mrad. The recorded pictures show wiggled and continuous proton traces which imply a release of the proton beam from the acceleration zone with a velocity chirp.

Schreiber, J.; Ter-Avetisyan, S.; Risse, E.; Kalachnikov, M.P.; Nickles, P.V.; Sandner, W.; Schramm, U.; Habs, D.; Witte, J.; Schnuerer, M. [MPI fuer Quantenoptik, Hans-Kopfermann-Str. 1, D 85748 Garching (Germany) and LMU Muenchen, Am Coulombwall 1, D 85748, Garching (Germany); Max Born Institut, Max Born Strasse 2a, D 12489 Berlin (Germany); Max Born Institut, Max Born Strasse 2a, D 12489 Berlin (Germany) and TU Berlin, Strasse des 17. Juni 135, D 10623 Berlin (Germany); LMU Muenchen, Am Coulombwall 1, D 85748, Garching (Germany); MPI fuer Quantenoptik, Hans-Kopfermann-Str. 1, D 85748 Garching (Germany); Max Born Institut, Max Born Strasse 2a, D 12489 Berlin (Germany)

2006-03-15

158

Relativistic particle acceleration in plerions  

NASA Technical Reports Server (NTRS)

We discuss recent research on the structure and particle acceleration properties of relativistic shock waves in which the magnetic field is transverse to the flow direction in the upstream medium, and whose composition is either pure electrons and positrons or primarily electrons and positrons with an admixture of heavy ions. Particle-in-cell simulation techniques as well as analytic theory have been used to show that such shocks in pure pair plasmas are fully thermalized -- the downstream particle spectra are relativistic Maxwellians at the temperature expected from the jump conditions. On the other hand, shocks containing heavy ions which are a minority constituent by number but which carry most of the energy density in the upstream medium do put approximately 20% of the flow energy into a nonthermal population of pairs downstream, whose distribution in energy space is N(E) varies as E(exp -2), where N(E)dE is the number of particles with energy between E and E+dE. The mechanism of thermalization and particle acceleration is found to be synchrotron maser activity in the shock front, stimulated by the quasi-coherent gyration of the whole particle population as the plasma flowing into the shock reflects from the magnetic field in the shock front. The synchrotron maser modes radiated by the heavy ions are absorbed by the pairs at their (relativistic) cyclotron frequencies, allowing the maximum energy achievable by the pairs to be gamma(sub +/-)m(sub +/-)c squared = m(sub i)c squared gamma(sub 1)/Z(sub i), where gamma(sub 1) is the Lorentz factor of the upstream flow and Z(sub i) is the atomic number of the ions. The shock's spatial structure is shown to contain a series of 'overshoots' in the magnetic field, regions where the gyrating heavy ions compress the magnetic field to levels in excess of the eventual downstream value. This shock model is applied to an interpretation of the structure of the inner regions of the Crab Nebula, in particular to the 'wisps,' surface brightness enhancements near the pulsar. We argue that these surface brightness enhancements are the regions of magnetic overshoot, which appear brighter because the small Larmor radius pairs are compressed and radiate more efficiently in the regions of more intense magnetic field. This interpretation suggests that the structure of the shock terminating the pulsar's wind in the Crab Nebula is spatially resolved, and allows one to measure gamma(sub 1) and a number of other properties of the pulsar's wind. We also discuss applications of the shock theory to the termination shocks of the winds from rotation-powered pulsars embedded in compact binaries. We show that this model adequately accounts for (and indeed predicted) the recently discovered X-ray flux from PSR 1957+20, and we discuss several other applications to other examples of these systems.

Arons, Jonathan; Tavani, Marco

1994-01-01

159

Observations of particle acceleration in solar flares  

NASA Technical Reports Server (NTRS)

Solar flares provide several examples of nonthermal particle acceleration. The paper reviews the information gained about these processes via X-ray and gamma-ray astronomy, which can presently distinguish among three separate particle-acceleration processes at the sun: an impulsive accelerator of more than 20 keV electrons, a gradual accelerator of more than 20 keV electrons, and a gradual accelerator of more than 10 MeV ions. The acceleration energy efficiency (total particle energy divided by total flare energy) of any of these mechanisms cannot be less than about 0.1%, although the gradual acceleration does not occur in every flare. The observational material suggests that both the impulsive and gradual accelerations take place preferentially in closed magnetic-field structures, but that the electrons decay in these traps before they can escape. The ions escape very efficiently.

Hudson, H. S.

1979-01-01

160

Beam Coupling to Optical Scale Accelerating Structures  

SciTech Connect

Current research efforts into structure based laser acceleration of electrons utilize beams from standard RF linacs. These beams must be coupled into very small structures with transverse dimensions comparable to the laser wavelength. To obtain decent transmission, a permanent magnet quadrupole (PMQ) triplet with a focusing gradient of 560 T/m is used to focus into the structure. Also of interest is the induced wakefield from the structure, useful for diagnosing potential accelerator structures or as novel radiation sources.

Sears, C.M.; Byer, R.L.; Colby, E.R.; Cowan, B.M.; Ischebeck, R.; Lincoln, M.R.; Siemann, R.H.; Spencer, J.E.; /SLAC; Plettner, T.; /Stanford U., Phys. Dept.

2007-03-27

161

Negative ion beam formation, transport and acceleration  

SciTech Connect

The BNL Neutral Beam Development Group is working on the development of negative ion based neutral beam systems, using high current density surface plasma sources of the magnetron and hollow cathode discharge (HCD) type. With the magnetron source, the plan is to transport a 2A D/sup -/ beam through a bending magnet before acceleration to 200 keV. In experiments with a pulsed magnetron, 0.4A of H/sup -/ was transported through a 90/sup 0/, n = 1, bending magnet with 80% transmission. With the lower operating pressure in the HCD source, close coupled acceleration will be applied. The MEQALAC, RFQ, and a dc accelerating scheme with periodic quadrupole focusing are considered for reaching higher energies. A preliminary experiment was performed with quadrupole beam transport and a 3.8 mA beam was transported through a series of twelve quadrupoles, with 3 mm apertures and a total length of 7.2 cm.

Alessi, J.G.

1981-01-01

162

Microwave accelerator E-beam pumped laser  

DOEpatents

A device and method for pumping gaseous lasers by means of a microwave accelerator. The microwave accelerator produces a relativistic electron beam which is applied along the longitudinal axis of the laser through an electron beam window. The incident points of the electron beam on the electron beam window are varied by deflection coils to enhance the cooling characteristics of the foil. A thyratron is used to reliably modulate the microwave accelerator to produce electron beam pulses which excite the laser medium to produce laser pulse repetition frequencies not previously obtainable. An aerodynamic window is also disclosed which eliminates foil heating problems, as well as a magnetic bottle for reducing laser cavity length and pressures while maintaining efficient energy deposition.

Brau, Charles A. (Los Alamos, NM) [Los Alamos, NM; Stein, William E. (Los Alamos, NM) [Los Alamos, NM; Rockwood, Stephen D. (Los Alamos, NM) [Los Alamos, NM

1980-01-01

163

Notes on beam dynamics in linear accelerators  

SciTech Connect

A collection of notes, on various aspects of beam dynamics in linear accelerators, which were produced by the author during five years (1975 to 1980) of consultation for the LASL Accelerator Technology (AT) Division and Medium-Energy Physics (MP) Division is presented.

Gluckstern, R.L.

1980-09-01

164

Production of high density proton currents for colliding beam accelerators  

Microsoft Academic Search

A head-on collision of two 15 GeV protons produces an energy in the centre of mass equivalent to about 500 GeV with the target at rest. To achieve significant production of secondaries, intense beams of particles are required, and this is obtained by `stacking' successive pulses of particles at high energy. Limitations imposed by the accelerating system are examined and

J. W. Burren; D. Morgan; W. Walkinshaw

1959-01-01

165

Studies of beam dynamics in relativistic klystron two- beam accelerators  

Microsoft Academic Search

Two-beam accelerators (TBAs) based upon free-electron lasers (FELs) or relativistic klystrons (RK-TBAs) have been proposed as efficient power sources for next generation high-energy linear colliders. Studies have demonstrated the possibility of building TBAs from X-band (~8-12 GHz) through Ka-band (~30-35 GHz) frequency regions. A new method of simulating the beam dynamics in accelerators of this type has been developed in

Steven Michael Lidia; Steven M

1999-01-01

166

Stochastic Particle Acceleration by Plasma Turbulence  

NASA Astrophysics Data System (ADS)

Particle acceleration takes place in many astrophysical setting and is manifested as Cosmic Rays or nonthermal particle (mainly electron) spectra in many sources of radiation. Shock acceleration is commonly invoked to describe these phenomena. However, in most mechanisms of acceleration, including shocks, plasma waves and turbulence appear to play a prominent role. Moreover, because of the high Reynold numbers prevailing in astrophysical plasmas turbulence is expected to be present. In this review the role of turbulence will be described and, in particular, its role in directly accelerating particles stochastically, as envisioned originally by Fermi, will be discussed. A brief review of astrophysical sources where this process may be important will be presented.

Petrosian, Vahé

2007-08-01

167

Type II radio bursts and particle acceleration  

Microsoft Academic Search

328 particle events recorded during 30 months from January 1, 1966 to June 30, 1968 (taken from the new Catalog of Solar Particle Events, 1955–1969) are compared with the occurrence of 166 type II radio bursts during the same period. The results of this comparison give a convincing evidence that proton acceleration to higher energies in flares (the ‘second acceleration

Z. Švestka; L. Fritzová-Svestková

1974-01-01

168

Introduction to Particle Acceleration in the Cosmos  

NASA Technical Reports Server (NTRS)

Accelerated charged particles have been used on Earth since 1930 to explore the very essence of matter, for industrial applications, and for medical treatments. Throughout the universe nature employs a dizzying array of acceleration processes to produce particles spanning twenty orders of magnitude in energy range, while shaping our cosmic environment. Here, we introduce and review the basic physical processes causing particle acceleration, in astrophysical plasmas from geospace to the outer reaches of the cosmos. These processes are chiefly divided into four categories: adiabatic and other forms of non-stochastic acceleration, magnetic energy storage and stochastic acceleration, shock acceleration, and plasma wave and turbulent acceleration. The purpose of this introduction is to set the stage and context for the individual papers comprising this monograph.

Gallagher, D. L.; Horwitz, J. L.; Perez, J.; Quenby, J.

2005-01-01

169

Beam Control for Ion Induction Accelerators  

SciTech Connect

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

Sangster, T.C.; Ahle, L.

2000-02-17

170

Particle acceleration in relativistic laser channels  

Microsoft Academic Search

Energy spectra of ions and fast electrons accelerated by a channeling laser pulse in near-critical plasma are studied using three-dimensional (3D) Particle-In-Cell simulations. The realistic 3D geometry of the simulations allows us to obtain not only the shape of the spectra, but also the absolute numbers of accelerated particles. It is shown that ions are accelerated by a collisionless radial

A. Pukhov; Z.-M. Sheng; J. Meyer-Ter-Vehn

1999-01-01

171

Indirectly sensing accelerator beam currents for limiting maximum beam current magnitude  

DOEpatents

A beam current limiter for sensing and limiting the beam current in a particle accelerator, such as a cyclotron or linear accelerator, used in scientific research and medical treatment. A pair of independently operable capacitive electrodes sense the passage of charged particle bunches to develop an RF signal indicative of the beam current magnitude produced at the output of a bunched beam accelerator. The RF signal produced by each sensing electrode is converted to a variable DC voltage indicative of the beam current magnitude. The variable DC voltages thus developed are compared to each other to verify proper system function and are further compared to known references to detect beam currents in excess of pre-established limits. In the event of a system malfunction, or if the detected beam current exceeds pre-established limits, the beam current limiter automatically inhibits further accelerator operation. A high Q tank circuit associated with each sensing electrode provides a narrow system bandwidth to reduce noise and enhance dynamic range. System linearity is provided by injecting, into each sensing electrode, an RF signal that is offset from the bunching frequency by a pre-determined beat frequency to ensure that subsequent rectifying diodes operate in a linear response region. The system thus provides a large dynamic range in combination with good linearity.

Bogaty, John M. (Lombard, IL); Clifft, Benny E. (Park Forest, IL); Bollinger, Lowell M. (Downers Grove, IL)

1995-01-01

172

Indirectly sensing accelerator beam currents for limiting maximum beam current magnitude  

DOEpatents

A beam current limiter is disclosed for sensing and limiting the beam current in a particle accelerator, such as a cyclotron or linear accelerator, used in scientific research and medical treatment. A pair of independently operable capacitive electrodes sense the passage of charged particle bunches to develop an RF signal indicative of the beam current magnitude produced at the output of a bunched beam accelerator. The RF signal produced by each sensing electrode is converted to a variable DC voltage indicative of the beam current magnitude. The variable DC voltages thus developed are compared to each other to verify proper system function and are further compared to known references to detect beam currents in excess of pre-established limits. In the event of a system malfunction, or if the detected beam current exceeds pre-established limits, the beam current limiter automatically inhibits further accelerator operation. A high Q tank circuit associated with each sensing electrode provides a narrow system bandwidth to reduce noise and enhance dynamic range. System linearity is provided by injecting, into each sensing electrode, an RF signal that is offset from the bunching frequency by a pre-determined beat frequency to ensure that subsequent rectifying diodes operate in a linear response region. The system thus provides a large dynamic range in combination with good linearity. 6 figs.

Bogaty, J.M.; Clifft, B.E.; Bollinger, L.M.

1995-08-08

173

Circular, confined distribution for charged particle beams  

DOEpatents

A charged particle beam line is formed with magnetic optics that manipulate the charged particle beam to form the beam having a generally rectangular configuration to a circular beam cross-section having a uniform particle distribution at a predetermined location. First magnetic optics form a charged particle beam to a generally uniform particle distribution over a square planar area at a known first location. Second magnetic optics receive the charged particle beam with the generally square configuration and affect the charged particle beam to output the charged particle beam with a phase-space distribution effective to fold corner portions of the beam toward the core region of the beam. The beam forms a circular configuration having a generally uniform spatial particle distribution over a target area at a predetermined second location.

Garnett, Robert W. (Los Alamos, NM); Dobelbower, M. Christian (Toledo, OH)

1995-01-01

174

Circular, confined distribution for charged particle beams  

DOEpatents

A charged particle beam line is formed with magnetic optics that manipulate the charged particle beam to form the beam having a generally rectangular configuration to a circular beam cross-section having a uniform particle distribution at a predetermined location. First magnetic optics form a charged particle beam to a generally uniform particle distribution over a square planar area at a known first location. Second magnetic optics receive the charged particle beam with the generally square configuration and affect the charged particle beam to output the charged particle beam with a phase-space distribution effective to fold corner portions of the beam toward the core region of the beam. The beam forms a circular configuration having a generally uniform spatial particle distribution over a target area at a predetermined second location. 26 figs.

Garnett, R.W.; Dobelbower, M.C.

1995-11-21

175

Laser particle acceleration: beat-wave and wakefield experiments  

Microsoft Academic Search

In a plasma, some of the energy of a high-power laser beam can be transferred to a longitudinal plasma wave with a high phase velocity. This wave can in turn accelerate relativistic charged particles to very high energies. Several mechanisms have been proposed to generate these intense electric fields and some of them have already been tested experimentally. Using the

F. Amiranoff; A. Antonetti; P. Audebert; D. Bernard; B. Cros; F. Dorchies; J. C. Gauthier; J. P. Geindre; G. Grillon; F. Jacquet; G. Matthieussent; J. R. Marquès; P. Miné; P. Mora; A. Modena; J. Morillo; F. Moulin; Z. Najmudin; A. E. Specka; C. Stenz

1996-01-01

176

Particle Accelerators Test Cosmological Theory.  

ERIC Educational Resources Information Center

Discusses the symbiotic relationship of cosmology and elementary-particle physics. Presents a brief overview of particle physics. Explains how cosmological considerations set limits on the number of types of elementary particles. (RT)

Schramm, David N.; Steigman, Gary

1988-01-01

177

Space experiments with particle accelerators  

NASA Technical Reports Server (NTRS)

Electron and plasma beams and neutral gas plumes were injected into the space environment by instruuments on Spacelab 1, and various diagnostic measurements including television camera observations were performed. The results yield information on vehicle charging and neutralization, beam-plasma interactions, and ionization enhancement by neutral beam injection.

Obayashi, T.; Kawashima, N.; Kuriki, K.; Nagatomo, M.; Ninomiya, K.; Sasaki, S.; Roberts, W. T.; Chappell, C. R.; Reasoner, D. L.; Garriott, O. K.; Taylor, W. W. L.

1984-01-01

178

Laser-driven shock acceleration of monoenergetic ion beams.  

PubMed

We show that monoenergetic ion beams can be accelerated by moderate Mach number collisionless, electrostatic shocks propagating in a long scale-length exponentially decaying plasma profile. Strong plasma heating and density steepening produced by an intense laser pulse near the critical density can launch such shocks that propagate in the extended plasma at high velocities. The generation of a monoenergetic ion beam is possible due to the small and constant sheath electric field associated with the slowly decreasing density profile. The conditions for the acceleration of high-quality, energetic ion beams are identified through theory and multidimensional particle-in-cell simulations. The scaling of the ion energy with laser intensity shows that it is possible to generate ~200 MeV proton beams with state-of-the-art 100 TW class laser systems. PMID:23215596

Fiuza, F; Stockem, A; Boella, E; Fonseca, R A; Silva, L O; Haberberger, D; Tochitsky, S; Gong, C; Mori, W B; Joshi, C

2012-11-21

179

Laser-Driven Shock Acceleration of Monoenergetic Ion Beams  

NASA Astrophysics Data System (ADS)

We show that monoenergetic ion beams can be accelerated by moderate Mach number collisionless, electrostatic shocks propagating in a long scale-length exponentially decaying plasma profile. Strong plasma heating and density steepening produced by an intense laser pulse near the critical density can launch such shocks that propagate in the extended plasma at high velocities. The generation of a monoenergetic ion beam is possible due to the small and constant sheath electric field associated with the slowly decreasing density profile. The conditions for the acceleration of high-quality, energetic ion beams are identified through theory and multidimensional particle-in-cell simulations. The scaling of the ion energy with laser intensity shows that it is possible to generate ˜200MeV proton beams with state-of-the-art 100 TW class laser systems.

Fiuza, F.; Stockem, A.; Boella, E.; Fonseca, R. A.; Silva, L. O.; Haberberger, D.; Tochitsky, S.; Gong, C.; Mori, W. B.; Joshi, C.

2012-11-01

180

Particle motion in crystalline beams  

SciTech Connect

Studying the possibility of storing a low emittance (or ``cooled``) beam of charged particles in a storage ring, the authors are faced with the effect of space charge by which particles are repelled and influence each others` motion. The correct evaluation of the space-charge effects is important to determine the attainment and properties of Crystalline Beams, a phase transition which intense beams of ions can undergo when cooling is applied. In this report they derive the equations of motion of a particle moving under the action of external resorting forces generated by the magnets of the storage ring, and of the electromagnetic fields generated by the other particles. The motion in every direction is investigated: in the longitudinal, as well as vertical and horizontal direction. The external forces are assumed to be linear with the particle displacement from the reference orbit. The space-charge forces are comparable in magnitude to the external focusing forces. The equations of motion so derived are then used to determine confinement and stability conditions for the attainment of Crystalline Beams, using transfer matrices.

Haffmans, A.F.; Maletic, D.; Ruggiero, A.G.

1994-04-20

181

Advanced visualization technology for terascale particle accelerator simulations  

Microsoft Academic Search

This paper presents two new hardware-assisted rendering techniques developed for interactive visualization of the terascale data generated from numerical modeling of next-generation accelerator designs. The first technique, based on a hybrid rendering approach, makes possible interactive exploration of large-scale particle data from particle beam dynamics modeling. The second technique, based on a compact texture-enhanced representation, exploits the advanced features of

Kwan-Liu Ma; Gregory L. Schussman; Brett Wilson; Kwok Ko; Ji Qiang; Robert Ryne

2002-01-01

182

Solitary waves in particle beams  

SciTech Connect

Since space charge waves on a particle beam exhibit both dispersive and nonlinear character, solitary waves or solitons are possible. Dispersive, nonlinear wave propagation in high current beams is found to be similar to ion-acoustic waves in plasmas with an analogy between Debye screening and beam pipe shielding. Exact longitudinal solitary wave propagation is found for potentials associated with certain transverse distributions which fill the beam pipe. For weak dispersion, the waves satisfy the Korteweg-deVries (KdV) equation, but for strong dispersion they exhibit breaking. More physically realizable distributions which do not fill the beam pipe are investigated and shown to also satisfy a KdV equation for weak dispersion if averaging over rapid transverse motion is physically justified. Scaling laws are presented to explore likely parameter regimes where these phenomena may be observed experimentally.

Bisognano, J.J. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)

1996-07-01

183

Advanced visualization technology for terascale particle accelerator simulations  

SciTech Connect

This paper presents two new hardware-assisted rendering techniques developed for interactive visualization of the terascale data generated from numerical modeling of next generation accelerator designs. The first technique, based on a hybrid rendering approach, makes possible interactive exploration of large-scale particle data from particle beam dynamics modeling. The second technique, based on a compact texture-enhanced representation, exploits the advanced features of commodity graphics cards to achieve perceptually effective visualization of the very dense and complex electromagnetic fields produced from the modeling of reflection and transmission properties of open structures in an accelerator design. Because of the collaborative nature of the overall accelerator modeling project, the visualization technology developed is for both desktop and remote visualization settings. We have tested the techniques using both time varying particle data sets containing up to one billion particle s per time step and electromagnetic field data sets with millions of mesh elements.

Ma, K-L; Schussman, G.; Wilson, B.; Ko, K.; Qiang, J.; Ryne, R.

2002-11-16

184

Feature-based analysis of plasma-based particle acceleration data.  

PubMed

Plasma-based particle accelerators can produce and sustain thousands of times stronger acceleration fields than conventional particle accelerators, providing a potential solution to the problem of the growing size and cost of conventional particle accelerators. To facilitate scientific knowledge discovery from the ever growing collections of accelerator simulation data generated by accelerator physicists to investigate next-generation plasma-based particle accelerator designs, we describe a novel approach for automatic detection and classification of particle beams and beam substructures due to temporal differences in the acceleration process, here called acceleration features. The automatic feature detection in combination with a novel visualization tool for fast, intuitive, query-based exploration of acceleration features enables an effective top-down data exploration process, starting from a high-level, feature-based view down to the level of individual particles. We describe the application of our analysis in practice to analyze simulations of single pulse and dual and triple colliding pulse accelerator designs, and to study the formation and evolution of particle beams, to compare substructures of a beam, and to investigate transverse particle loss. PMID:24356363

Rübel, Oliver; Geddes, Cameron G R; Chen, Min; Cormier-Michel, Estelle; Bethel, E Wes

2014-02-01

185

Charged Particle Acceleration by Lasers in Plasmas  

SciTech Connect

Several physical processes of laser electron acceleration in plasmas are revisited. A laser beam can drive plasma waves which in turn can accelerate resonant electrons. If these plasma waves can reach amplitude limited only by wave breaking alone, then the corresponding accelerating gradient in the plasma wave is of the order of electron rest mass energy per plasma skin depth, typically about GEV per centimeter. This is several orders of magnitudes higher than the conventional RF field gradient, giving rise to the possibility of compact accelerators needed for high energy physics research as well as medical and other applications. The chirped short pulse laser, with intensity exceeding the threshold for relativistic self focusing, can generate ion bubble in its wake by expelling electrons. The electrons at the bubble boundary, surge toward the stagnation point and pile up there. As the pile acquires a critical size, these electrons are injected into the bubble and accelerated by the combined fields of ion space charge and the plasma wave to Gev in energy. Most remarkably these electrons are bunched in phase space while being accelerated to high energy, resulting in near mono-energetic electron beam of high beam quality, with narrow energy spread. We review also other processes related to laser electron acceleration, such as acceleration in plasma wave assisted by ponderomotive force and betatron acceleration.

Liu, C. S.; Tripathi, V. K. [Department of Physics, University of Maryland, College Park, MD 20742 (United States)

2007-07-11

186

Beam Head Erosion in Self-Ionized Plasma Wakefield Accelerators  

SciTech Connect

In the recent plasma wakefield accelerator experiments at SLAC, the energy of the particles in the tail of the 42 GeV electron beam were doubled in less than one meter [1]. Simulations suggest that the acceleration length was limited by a new phenomenon--beam head erosion in self-ionized plasmas. In vacuum, a particle beam expands transversely in a distance given by {beta}*. In the blowout regime of a plasma wakefield [2], the majority of the beam is focused by the ion channel, while the beam head slowly spreads since it takes a finite time for the ion channel to form. It is observed that in self-ionized plasmas, the head spreading is exacerbated compared to that in pre-ionized plasmas, causing the ionization front to move backward (erode). A simple theoretical model is used to estimate the upper limit of the erosion rate for a bi-gaussian beam by assuming free expansion of the beam head before the ionization front. Comparison with simulations suggests that half this maximum value can serve as an estimate for the erosion rate. Critical parameters to the erosion rate are discussed.

Berry, M.K.; Blumenfeld, I.; Decker, F.J.; Hogan, M.J.; Ischebeck, R.; Iverson, R.H.; Kirby, N.A.; Siemann, Robert H.; Walz, D.R.; /SLAC; Clayton, C.E.; Huang, C.; Joshi, C.; Lu, W.; Marsh, K.A.; Mori, W.B.; Zhou, M.; /UCLA; Katsouleas, T.C.; Muggli, P.; Oz, E.; /Southern California U.

2008-01-28

187

Discrete beam acceleration in uniform waveguide arrays  

SciTech Connect

Within the framework of the tight-binding model we demonstrate that Wannier-Stark states can freely accelerate in uniform optical lattices. As opposed to accelerating Airy wave packets in free space, our analysis reveals that in this case the beam main intensity features self-bend along two opposite hyperbolic trajectories. Two-dimensional geometries are also considered and an asymptotic connection between these Wannier-Stark ladders and Airy profiles is presented.

El-Ganainy, Ramy [Department of Physics, University of Toronto, 60 St. George Street, Toronto, Ontario, M5S 1A7 (Canada); Makris, Konstantinos G. [Institute for Theoretical Physics, Vienna University of Technology, A-1040 Vienna (Austria); Miri, Mohammad Ali; Christodoulides, Demetrios N. [College of Optics-CREOL, University of Central Florida, Orlando, Florida 32816 (United States); Chen Zhigang [Department of Physics and Astronomy, San Francisco State University, San Francisco, California 94132 (United States)

2011-08-15

188

Particle beam weapons - A technical assessment  

Microsoft Academic Search

The technical feasibility, principles, problems and potential of particle beam weapons are assessed. The mechanisms by which deposition of the energy of a beam of energetic particles leads to target damage and the energy required to inflict such damage are discussed, and effects which impede the propagation of charged particle beams in space are examined; problems with neutral hydrogen beams

G. Bekefi; B. T. Feld; J. Parmentola; K. Tsipis

1980-01-01

189

Negative ion beam acceleration and transport  

SciTech Connect

The optimum conditions for focusing a negative ion beam are discussed. The distribution of the current between the Faraday cup and a large ring collector, surrounding this cup, has been investigated experimentally and theoretically, at constant extraction voltage (1.9 kV), with the acceleration voltage being varied in a wide range. The effects of beam space charge, negative ion temperature, and stripping are analyzed.

Michaut, C.; Devynck, P.; Bacal, M.; Sledziewski, Z.; Valckx, F.P.G. (Laboratoire de Physique des Milieux Ionises, Laboratoire du C.N.R.S., Ecole Polytechnique, 91128 Palaiseau (France)); Whealton, J.H.; Raridon, R.J. (Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8071 (United States))

1992-04-01

190

Frequency multiplying oscillator with an electron beam accelerated in a drift space  

SciTech Connect

In a uniform acceleration region, the behavior of a velocity-modulated electron beam has been analyzed using a particle-in-cell code. By making use of one of the accelerated harmonic components of the velocity-modulated electron beam, we demonstrate a frequency multiplying oscillator for a compact THz emitter, which employs multiple electron beams and a higher order mode resonator to modulate the electron beam without an additional driving source.

Jang, Kyu-Ha; Lee, Kitae; Hee Park, Seong; Uk Jeong, Young [WCI Center for Quantum Beam-based Radiation Research, Korea Atomic Energy Research Institute, 1045 Deadeok, Yuseong, Daejeon 305-353 (Korea, Republic of); Miginsky, S. [WCI Center for Quantum Beam-based Radiation Research, Korea Atomic Energy Research Institute, 1045 Deadeok, Yuseong, Daejeon 305-353 (Korea, Republic of); Budker Institute of Nuclear Physics, SB RAS, Academician Lavrentyev St. 11, Novosibrisk (Russian Federation)

2012-07-02

191

Solar particle acceleration and propagation  

Microsoft Academic Search

Experimental and theoretical results concerning the acceleration of solar radiation are reviewed. Different types of radiations are considered separately including neutrons, electrons, gamma rays, and He-rich events. (AIP)

R. P. Lin

1987-01-01

192

Accelerating diffraction-free beams in photonic lattices.  

PubMed

We study nondiffracting accelerating paraxial optical beams in periodic potentials, in both the linear and the nonlinear domains. In particular, we show that only a unique class of z-dependent lattices can support a true accelerating diffractionless beam. Accelerating lattice solitons, autofocusing beams and accelerating bullets in optical lattices are systematically examined. PMID:24686692

Makris, K G; Kaminer, I; El-Ganainy, R; Efremidis, N K; Chen, Zhigang; Segev, M; Christodoulides, D N

2014-04-01

193

A report on the possible benefits of using high-temperature superconductor materials in particle accelerator design  

NASA Astrophysics Data System (ADS)

This report discusses different design concepts for particle beam accelerators. It demonstrates that with the use of high temperature superconducting materials, a more compact, lighter, and more robust accelerator design can be realized for the space based Neutral Particle Beam (NPB) accelerator.

Cohen, Leslie; Collins, Robert; Balko, Bohdan

1988-12-01

194

Harmonic Ratcheting for Ferrite Tuned RF Acceleration of Charged Particles  

NASA Astrophysics Data System (ADS)

One of the most persistent difficulties in the design of RF cavities for acceleration of charged particles is the rapid and efficient acceleration of particles over a large range of frequencies. From medical synchrotrons to accelerator driven systems, there is a strong need for fast acceleration of protons and light ions over hundreds of MeV. Conventionally, this is a costly undertaking, requiring specially designed ferrite loaded cavities to be tuned over a large range of frequencies. Ferromagnetic materials allow for the precise adjustment of cavity resonant frequency, but rapid changes in the frequency as well as operation outside material specific frequency ranges result in significant Q-loss to the cavity. This leads to a considerable increase in power required and is thus undesirable for regular operation. We introduce an acceleration scheme known as harmonic ratcheting which can be used to reduce the cavity frequency range needed for accelerating an ion beam in a synchrotron. In particular, this scheme addresses the need for high rep. rate machines for applications such as radiation therapy in which low beam intensity is needed. We demonstrate with simulations the type of ramps achievable using this technique and consider its advantages over h=1 acceleration schemes.

Cook, Nathan; Brennan, Mike

2013-04-01

195

Single particle dynamics in circular accelerators  

SciTech Connect

The purpose of this paper is to introduce the reader to the theory associated with the transverse dynamics of single particle, in circular accelerators. The discussion begins with a review of Hamiltonian dynamics and canonical transformations. The case of a single particle in a circular accelerator is considered with a discussion of non-linear terms and chromaticity. The canonical perturbation theory is presented and nonlinear resonances are considered. Finally, the concept of renormalization and residue criterion are examined. (FI)

Ruth, R.D.

1986-10-01

196

S-Code for Fixed Field Alternating Gradient Accelerator Design and Particle Tracking  

NASA Astrophysics Data System (ADS)

The constant field nature of a fixed field alternating gradient (FFAG) accelerator requires a modeling which separates the layout of accelerator elements from the geometry of beam orbits. A new code, named s-code, is made to design an FFAG accelerator and to track a beam in it. We will describe the model of accelerator elements and the way to integrate the equation of motion of a particle.

Machida, Shinji

197

On the use of the autocorrelation and covariance methods for feedforward control of transverse angle and position jitter in linear particle beam accelerators  

SciTech Connect

It is desired to design a predictive feedforward transverse jitter control system to control both angle and position jitter in pulsed linear accelerators. Such a system will increase the accuracy and bandwidth of correction over that of currently available feedback correction systems. Intrapulse correction is performed. An offline process actually {open_quotes}learns{close_quotes} the properties of the jitter, and uses these properties to apply correction to the beam. The correction weights calculated offline are downloaded to a real-time analog correction system between macropulses. Jitter data were taken at the Los Alamos National Laboratory (LANL) Ground Test Accelerator (GTA) telescope experiment at Argonne National Laboratory (ANL). The experiment consisted of the LANL telescope connected to the ANL ZGS proton source and linac. A simulation of the correction system using this data was shown to decrease the average rms jitter by a factor of two over that of a comparable standard feedback correction system. The system also improved the correction bandwidth.

Barr, D.S.

1993-11-01

198

A technology platform for translational research on laser driven particle accelerators for radiotherapy  

NASA Astrophysics Data System (ADS)

It is widely accepted that proton or light ion beams may have a high potential for improving cancer cure by means of radiation therapy. However, at present the large dimensions of electromagnetic accelerators prevent particle therapy from being clinically introduced on a broad scale. Therefore, several technological approaches among them laser driven particle acceleration are under investigation. Parallel to the development of suitable high intensity lasers, research is necessary to transfer laser accelerated particle beams to radiotherapy, since the relevant parameters of laser driven particle beams dramatically differ from those of beams delivered by conventional accelerators: The duty cycle is low, whereas the number of particles and thus the dose rate per pulse are high. Laser accelerated particle beams show a broad energy spectrum and substantial intensity fluctuations from pulse to pulse. These properties may influence the biological efficiency and they require completely new techniques of beam delivery and quality assurance. For this translational research a new facility is currently constructed on the campus of the university hospital Dresden. It will be connected to the department of radiooncology and host a petawatt laser system delivering an experimental proton beam and a conventional therapeutic proton cyclotron. The cyclotron beam will be delivered on the one hand to an isocentric gantry for patient treatments and on the other hand to an experimental irradiation site. This way the conventional accelerator will deliver a reference beam for all steps of developing the laser based technology towards clinical applicability.

Enghardt, W.; Bussmann, M.; Cowan, T.; Fiedler, F.; Kaluza, M.; Pawelke, J.; Schramm, U.; Sauerbrey, R.; Tünnermann, A.; Baumann, M.

2011-05-01

199

Neutral Particle Beam Test Stand (NPBTS): Overview and capabilities  

Microsoft Academic Search

The Neutral Particle Beam Test Stand provides a versatile user facility for scientific and engineering studies on large-diameter, low-divergence neutral and charged particle beams. It consists of a linac that accelerates H\\/sup minus\\/ atoms to 50 MeV at 10--12 mA and two experimental areas. Typical pulse widths are 30--150 ..mu..s at repetition rates of 0.5--30 Hz. A small rms-emittance is

C. L. Fink; A. H. Novick; F. O. Bellinger; F. R. Brumwell; C. T. Roche; M. Rosing; T. J. Yule; C. R. Hummer

1989-01-01

200

Design and testing of a supercritical helium beamline cryopump for a neutral particle beam in space  

Microsoft Academic Search

As part of the BEAR Project (Beam Experiments Aboard a Rocket), being conducted by the Los Alamos National Laboratory and sponsored by the SDIO, the first ever flight qualified beamline cryopump for a neutral particle beam in space, has been designed, fabricated and tested. The BEAR payload consists primarily of a neutral particle beam accelerator whose injector produces a beam

J. Bascunan; J. F. Maguire

1990-01-01

201

Experimental Measurements of the Secondary Electron Yield in the Experimental Measurement of the Secondary Electron Yield in the PEP-II Particle Accelerator Beam Line  

SciTech Connect

Beam instability caused by the electron cloud has been observed in positron and proton storage rings and it is expected to be a limiting factor in the performance of the positron Damping Ring (DR) of future Linear Colliders (LC) such as ILC and CLIC. To test a series of promising possible electron cloud mitigation techniques as surface coatings and grooves, in the Positron Low Energy Ring (LER) of the PEP-II accelerator, we have installed several test vacuum chambers including (i) a special chamber to monitor the variation of the secondary electron yield of technical surface materials and coatings under the effect of ion, electron and photon conditioning in situ in the beam line; (ii) chambers with grooves in a straight magnetic-free section; and (iii) coated chambers in a dedicated newly installed 4-magnet chicane to study mitigations in a magnetic field region. In this paper, we describe the ongoing R&D effort to mitigate the electron cloud effect for the LC damping ring, focusing on the first experimental area and on results of the reduction of the secondary electron yield due to in situ conditioning.

Pivi, M.T.F.; Collet, G.; King, F.; Kirby, R.E.; Markiewicz, T.; Raubenheimer, T.O.; Seeman, J.; /SLAC; Le Pimpec, F.; /PSI, Villigen

2010-08-25

202

Accelerating and storing polarized hadron beams  

SciTech Connect

Polarization hadron experiments at high energies continue to generate surprises. Many questions remain unanswered or unanswerable within the frame work of QCD. These include such basic questions as to why at high energies the polarization analyzing power in pp elastic scattering remains high, why hyperons are produced with high polarizations etc. It is, therefore, interesting to investigate the possibilities of accelerating and storing polarized beams in high energy colliders. On the technical side the recent understanding and confirmation of the actions of partial and multiple Siberian snakes made it possible to contemplate accelerating and storing polarized hadron beams to multi-TeV energies. In this paper, we will examine the equipment, the operation and the procedure required to obtain colliding beams of polarized protons at TeV energies.

Teng, L.C.

1990-10-01

203

Understanding particle acceleration at supernova shocks  

NASA Astrophysics Data System (ADS)

One century after the pioneering discovery of cosmic rays by V. Hess, the present generation of X- and gamma-ray telescopes is finally unravelling the origin of such an extraterrestrial radiation, at least for what concerns particles with energies below ˜10^8 GeV, which are thought to be accelerated at the forward shocks of Galactic supernova remnants (SNRs). I discuss the present theoretical understanding of efficient particle acceleration at non-relativistic, collisionless shocks, addressing with both analytical and numerical (particle-in-cell) techniques the crucial interplay between accelerated ions and magnetic turbulence. In SNRs, in fact, magnetic fields turn out to be a factor of 10-100 larger than in the interstellar medium, because of plasma instabilities triggered by energetic particles. In particular, I show 2D and 3D hybrid (fluid electrons - kinetic ions) simulations of non-relativistic collisionless shocks, pointing out the efficiency of Fermi acceleration and the role of the cosmic-ray-induced filamentation instability in amplifying the magnetic field up to the levels inferred at the blast waves of young Galactic remnants. Finally, I outline the observational counterparts of such a theory of particle acceleration at strong shocks in terms of SNR multi-wavelength emission, with a special attention to Tycho's SNR, arguably the best laboratory where to test hadron acceleration.

Caprioli, Damiano

2013-04-01

204

Head accelerations during particle repositioning manoeuvres.  

PubMed

Benign paroxysmal positional vertigo (BPPV) due to canalithiasis can be treated with particle repositioning manoeuvres, which aim to evacuate trapped particles from the semicircular canals (SCC). The movement of particles within the SCC is affected by gravity as well as by the accelerations of the head during the manoeuvres. Moreover, as experienced by the particles, gravity is indistinguishable from an upward acceleration of the SCC in free space. We used a set of three orthogonal linear accelerometers to measure the net three-dimensional linear acceleration vector acting on the head during the Hallpike manoeuvre and Epley and Semont particle repositioning manoeuvres (which are used to treat posterior canal BPPV). The projection of the net acceleration vector onto the SCC planes showed that both the Epley and Semont manoeuvres approximated to stepwise, 360 degrees , backward rotations in the plane of the targeted posterior canal. Angular velocity measurements however showed that the rotational component during the central stages of these two manoeuvres is opposite in direction. A simple model of head rotations during particle repositioning manoeuvres was created which showed good agreement to the linear acceleration measurements. Analysis of modelled and measured data identified that speed of movement during the Semont manoeuvre should be critical to its clinical success. PMID:18525198

Faldon, M E; Bronstein, A M

2008-01-01

205

Particle Acceleration at Interplanetary Shocks  

NASA Astrophysics Data System (ADS)

The acceleration of interstellar pick-up ions as well as solar wind species has been observed at a multitude of interplanetary (IP) shocks by different spacecraft. The efficiency of injection of the pick-up ion component differs from that of the solar wind, and is strongly enhanced at highly oblique and quasi-perpendicular shock events. This paper expands upon previous work modeling the phase space distributions of accelerated ions associated with the shock event encountered on day 292 of 1991 by the Ulysses mission at 4.5 AU. As in the prior work, a kinetic Monte Carlo simulation is employed here to model the diffusive acceleration process. This exposition presents recent developments pertaining to the incorporation into the simulation of the diffusive characteristics incurred by field line wandering (FLW), according to the work of Giacalone and Jokipii. Resulting ion distributions and upstream diffusion scales are presented and compared with Ulysses data. For a pure field-line wandering construct, it is determined that the upstream spatial ramp scales are too short to accommodate the HI-SCALE flux increases for 200 keV protons, and that the distribution function for H+ somewhat underpopulates the combined SWICS/HI-SCALE spectra at the shock. This contrasts our earlier theory/data comparison where it was demonstrated that diffusive transport in highly turbulent fields according to kinetic theory can successfully account for both the proton distribution data near the shock, and the observation of energetic protons upstream of this interplanetary shock, using a single turbulence parameter. The principal conclusion here is that, in a FLW scenario, the transport of ions across the mean magnetic field is slightly less efficient than is required to effectively trap energetic ions within a few Larmor radii of the shock layer, and thereby sustain acceleration at levels that match the observed distributions. This highlights the contrast between ion transport in highly turbulent shock environs and remote, less-disturbed interplanetary regions.

Baring, Matthew G.; Summerlin, Errol J.

2008-08-01

206

Beam dynamics simulation of the Spallation Neutron Source linear accelerator  

SciTech Connect

The accelerating structure for Spallation Neutron Source (SNS) consists of a radio-frequency-quadrupole-linac (RFQ), a drift-tube-linac (DTL), a coupled-cavity-drift-tube-linac (CCDTL), and a coupled-cavity-linac (CCL). The linac is operated at room temperature. The authors discuss the detailed design of linac which accelerates an H{sup {minus}} pulsed beam coming out from RFQ at 2.5 MeV to 1000 MeV. They show a detailed transition from 402.5 MHz DTL with a 4 {beta}{lambda} structure to a CCDTL operated at 805 MHz with a 12 {beta}{lambda} structure. After a discussion of overall feature of the linac, they present an end-to-end particle simulation using the new version of the PARMILA code for a beam starting from the RFQ entrance through the rest of the linac. At 1000 MeV, the beam is transported to a storage ring. The storage ring requires a large ({+-}500-keV) energy spread. This is accomplished by operating the rf-phase in the last section of the linac so the particles are at the unstable fixed point of the separatrix. They present zero-current phase advance, beam size, and beam emittance along the entire linac.

Takeda, H.; Billen, J.H.; Bhatia, T.S.

1998-12-31

207

Reconstruction of lattice parameters and beam momentum distribution from turn-by-turn beam position monitor readings in circular accelerators  

NASA Astrophysics Data System (ADS)

In high chromaticity circular accelerators, rapid decoherence of the betatron motion of a particle beam can make the measurement of lattice and bunch values, such as Courant-Snyder parameters and betatron amplitude, difficult. A method for reconstructing the momentum distribution of a beam from beam position measurements is presented. Further analysis of the same beam position monitor data allows estimates to be made of the Courant-Snyder parameters and the amplitude of coherent betatron oscillation of the beam. The methods are tested through application to data taken on the linear nonscaling fixed field alternating gradient accelerator, EMMA.

Edmonds, C. S.; Gratus, J.; Hock, K. M.; Machida, S.; Muratori, B. D.; Torromé, R. G.; Wolski, A.

2014-05-01

208

Early experiments in charged particle beams from the Space Shuttle  

NASA Technical Reports Server (NTRS)

Characteristics of studies on board the Shuttle involving the interaction of particle beams with the atmosphere and the ionosphere, and the effects of the beams on the electrical potential of the platform, are discussed. Noting that the Shuttle allows greater weight and power demands by scientific payloads than previous satellite launches, the OSS-1 Vehicle Charging and Potential experiment and the Spacelab 1 Particle Accelerator and Phenomena Induced by Charged Particle Beams are described. Instrumentation details are provided, including charge and current probes, the Spherical Retarding Potential Analyzer, the Fast Pulse Electron Generator, and digital control and interface units. The SEPAC equipment, which comprises an electron beam accelerator, and MPD plasma jet, and diagnostic units are detailed, and operating procedures and experiment objectives are outlined.

Raitt, W. J.; Banks, P. M.; Williamson, P. R.; Baker, K. D.; Obayashi, T.; Burch, J. L.

1982-01-01

209

Adiabatic matching section for plasma accelerated beams  

NASA Astrophysics Data System (ADS)

An adiabatic matching section is discussed as option to control the divergence and emittance growth of a beam exiting a plasma channel. Based on a general analytical solution of a focusing channel with varying focusing strength, a focusing profile is proposed which allows for a fast expansion of the beam size while keeping the emittance growth minimal. The solution is also applicable to other cases, e.g., the matching of a positron source to the downstream accelerating section, which are, however, not discussed in this contribution.

Floettmann, Klaus

2014-05-01

210

High-powered pulsed-ion-beam acceleration and transport  

SciTech Connect

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.

Humphries, S. Jr.; Lockner, T.R.

1981-11-01

211

Detrapping accelerations in a strong electron-beam  

NASA Astrophysics Data System (ADS)

Modulation instabilities and particle-trapping have been observed in space plasmas, and thus it is important to simulate such phenomena in laboratory experiments. In our previous works, electron-beam holes induced by self-trapping were experimentally turned up in phase-space in a weak electron-beam, and their behaviors from emergences to collapses were exhibited [1]. In this work, the self-trapping is further investigated in a strong electron-beam. It is observed that electron-beam branches are formed next to the holes in the high velocity side, and expand with time. These imply that the beam-electrons are detrapped from potential wells of a wave packet. It is confirmed with plotting velocity tips of the branches that the square velocities are proportional to the positions. This proves that accelerations for the beam occur as a result of taking away the wave energy. The holes may play an important role in the accelerations.[1] T. Takeda and K. Yamagiwa, Phys. lett. A, 339, 118-122 (2005).

Takeda, Tsuyoshi

2005-10-01

212

Laser-driven beam lines for delivering intensity modulated radiation therapy with particle beams  

SciTech Connect

Laser-accelerated particles can provide a promising opportunity for radiation therapy of cancer. Potential advantages arise from combining a compact, cost-efficient treatment unit with the physical advantages in dose delivery of charged particle beams. We consider different dose delivery schemes and the required devices to design a possible treatment unit. The secondary radiation produced in several beam line elements remains a challenge to be addressed.

Hofmann, K. M.; Schell, S.; Wilkens, J. J. [Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 München (Germany)] [Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 München (Germany)

2013-07-26

213

Particle acceleration at a reconnecting magnetic separator  

NASA Astrophysics Data System (ADS)

We present first results of test particle orbit calculations in a time-dependent electro-magnetic field configuration which models separator reconnection in three dimensions. The test particle orbits are calculated using the relativistic guiding-centre approximation. The test particles are accelerated to high kinetic energies by the parallel electric field generically associated with three-dimensional magnetic reconnection, with the final energy depending on the choice of model parameters. We will discuss how the test-particle orbits and the energy gain depend on the initial conditions, and how observations (for example, of solar flares) may be used to constrain our model parameters.

Threlfall, James; Neukirch, Thomas; Parnell, Clare; Eradat Oskoui, Solmaz

2014-05-01

214

Magnetospheric reconnection, substorms, and energetic particle acceleration  

NASA Technical Reports Server (NTRS)

The steady state reconnection model of the terrestrial magnetosphere predicts a maximum potential drop of about 100 kV across the tail. During substorms particles are accelerated to energies above 1 MeV. At substorm onset, large inductive emfs may be generated by explosive tearing mode reconnection which is driven nonlinearly unstable by the solar wind and convection stresses on the tail plasma sheet. In the inner magnetosphere, energetic particles are also produced by stochastic wave turbulent acceleration and by convection driven inward radial diffusion.

Coroniti, F. V.; Kennel, C. F.

1979-01-01

215

Laser steering of particle beams: Refraction and reflection ofparticle beams  

SciTech Connect

The co-propagation of an intense particle beam with an ionizing laser beam in a working gas/plasma is considered. When the axes of the laser and particle beam are not aligned, then asymmetric plasma lensing results in a net dipole field acting on the particle beam. The particle beam can be steered or bent (as well as focused) by steering the laser. An analogy is made between the bending of the particle beam by collective effects at a plasma boundary and the refraction or reflection of light at an interface. This mechanism of particle steering may be of interest in applications for which permanent magnets are inconvenient of a fast turn on is required. 3-D particle-in-cell simulations and relevance to a recent experiment are discussed.

Esarey, Eric; Katsouleas, T.; Mori, W.B.; Dodd, E.; Lee, S.; Hemker, R.; Clayton, C.; Joshi, C.

1999-11-01

216

Space experiments with particle accelerators (SEPAC): Description of instrumentation  

NASA Technical Reports Server (NTRS)

SEPAC (Space Experiments with Particle Accelerators) flew on Spacelab 1 (SL 1) in November and December 1983. SEPAC is a joint U.S.-Japan investigation of the interaction of electron, plasma, and neutral beams with the ionosphere, atmosphere and magnetosphere. It is scheduled to fly again on Atlas 1 in August 1990. On SL 1, SEPAC used an electron accelerator, a plasma accelerator, and neutral gas source as active elements and an array of diagnostics to investigate the interactions. For Atlas 1, the plasma accelerator will be replaced by a plasma contactor and charge collection devices to improve vehicle charging meutralization. This paper describes the SEPAC instrumentation in detail for the SL 1 and Atlas 1 flights and includes a bibliography of SEPAC papers.

Taylor, W. W. L.; Roberts, W. T.; Reasoner, D. L.; Chappell, C. R.; Baker, B. B.; Burch, J. L.; Gibson, W. C.; Black, R. K.; Tomlinson, W. M.; Bounds, J. R.

1987-01-01

217

Statistical phenomena in particle beams  

SciTech Connect

Particle beams are subject to a variety of apparently distinct statistical phenomena such as intrabeam scattering, stochastic cooling, electron cooling, coherent instabilities, and radiofrequency noise diffusion. In fact, both the physics and mathematical description of these mechanisms are quite similar, with the notion of correlation as a powerful unifying principle. In this presentation we will attempt to provide both a physical and a mathematical basis for understanding the wide range of statistical phenomena that have been discussed. In the course of this study the tools of the trade will be introduced, e.g., the Vlasov and Fokker-Planck equations, noise theory, correlation functions, and beam transfer functions. Although a major concern will be to provide equations for analyzing machine design, the primary goal is to introduce a basic set of physical concepts having a very broad range of applicability.

Bisognano, J.J.

1984-09-01

218

Neutral Particle Beam Intensity Controller.  

National Technical Information Service (NTIS)

The neutral beam intensity controller is based on selected magnetic defocusing of the ion beam prior to neutralization. The defocused portion of the beam is dumped onto a beam dump disposed perpendicular to the beam axis. Selective defocusing is accomplis...

W. K. Dagenhart

1984-01-01

219

Energy Amplification and Beam Bunching in a Pulse Line Ion Accelerator  

SciTech Connect

In a first beam dynamics validation experiment for a new Pulse Line Ion Acceleration (PLIA) concept, the predicted energy amplification and beam bunching were experimentally observed. Beam energy modulation of -80 keV to +150 keV was measured using a PLIA input voltage waveform of -21 kV to +12 kV. Ion pulses accelerated by 150 keV, and bunching by a factor of four were simultaneously achieved. The measured longitudinal phase space and current waveform of the accelerated beam are in good agreement with 3-D particle-in-cell simulations.

Roy, P K; Waldron, W L; Yu, S S; Coleman, J E; Henestroza, E; Grote, D P; Baca, D; Bieniosek, F M; Briggs, R J; Davidson, R C; Eylon, S; Friedman, A; Greenway, W G; Leitner, M; Logan, G B; Reginato, L L; Seidl, P A

2006-06-08

220

Accelerators for charged particle therapy: PAMELA and related issues  

NASA Astrophysics Data System (ADS)

Cancer is a dreadful disease that will affect one in three people at some point in their life; radiotherapy is used in more than half of all cancer treatment, and contributes about 40% to the successful treatment of cancer. Charged Particle Therapy uses protons and other light ions to deliver the lethal dose to the tumor while being relatively sparing of healthy tissue and, because of the finite range of the particles, is able to avoid giving any dose to vital organs. While there are adequate technologies currently available to deliver the required energies and fluxes, the two main technologies (cyclotrons and synchrotrons) have limitations. PAMELA (the Particle Accelerator for MEdicaL Applications) uses the newly-developed non-scaling Fixed Field Alternating Gradient accelerator concepts to deliver therapeutically relevant beams. The status of the development of the PAMELA conceptual design is discussed.

Peach, Ken

2014-05-01

221

Particle Acceleration in Active Galactic Nuclei  

NASA Technical Reports Server (NTRS)

The high efficiency of energy generation inferred from radio observations of quasars and X-ray observations of Seyfert active galactic nuclei (AGNs) is apparently achieved only by the gravitational conversion of the rest mass energy of accreting matter onto supermassive black holes. Evidence for the acceleration of particles to high energies by a central engine is also inferred from observations of apparent superluminal motion in flat spectrum, core-dominated radio sources. This phenomenon is widely attributed to the ejection of relativistic bulk plasma from the nuclei of active galaxies, and accounts for the existence of large scale radio jets and lobes at large distances from the central regions of radio galaxies. Reports of radio jets and superluminal motion from galactic black hole candidate X-ray sources indicate that similar processes are operating in these sources. Observations of luminous, rapidly variable high-energy radiation from active galactic nuclei (AGNs) with the Compton Gamma Ray Observatory show directly that particles are accelerated to high energies in a compact environment. The mechanisms which transform the gravitational potential energy of the infalling matter into nonthermal particle energy in galactic black hole candidates and AGNs are not conclusively identified, although several have been proposed. These include direct acceleration by static electric fields (resulting from, for example, magnetic reconnection), shock acceleration, and energy extraction from the rotational energy of Kerr black holes. The dominant acceleration mechanism(s) operating in the black hole environment can only be determined, of course, by a comparison of model predictions with observations. The purpose of the work proposed for this grant was to investigate stochastic particle acceleration through resonant interactions with plasma waves that populate the magnetosphere surrounding an accreting black hole. Stochastic acceleration has been successfully applied to the problem of ion and electron energization in solar flares, and is capable of accounting for a wide range of both neutral and charged particle emissions. It is also a component in diffusive shock acceleration, since pitch-angle scattering (which is necessary for multiple shock crossings) is accompanied by diffusion in momentum space, which in turn yields a net systematic energy gain; however, stochastic energization will dominate the first-order shock process only in certain parameter regimes. Although stochastic acceleration has been applied to particle energization in the lobes of radio galaxies, its application to the central regions of AGNs has only recently been considered, but not in detail. We proposed to systematically investigate the plasma processes responsible for stochastic particle acceleration in black hole magnetospheres along with the energy-loss processes which impede particle energization. To this end we calculated acceleration rates and escape time scales for protons and electrons resonating with Alfven waves, and for electrons resonating with whistlers. Assuming either a Kolmogorov or Kraichnan wave spectrum, accretion at the Eddington limit, magnetic field strengths near equipartition, and turbulence energy densities approx. 10% of the total magnetic field energy density, we find that Alfven waves accelerate protons to Lorentz factors approx, equals 10(exp 4) - 10(exp 6) before they escape from the system. Acceleration of electrons by fast mode and whistler waves can produce a nonthermal population of relativistic electrons whose maximum energy is determined by a competition with radiation losses.

Miller, James A.

1997-01-01

222

The development of laser- and beam-driven plasma accelerators as an experimental field  

SciTech Connect

Since its inception in the early 1980s, the field of plasma-based particle accelerators has made remarkable advances. Robust plasma accelerating structures can now be excited over centimeter scales using short laser pulses and over meter scales using ultrarelativistic particle beams. Accelerating fields in excess of tens of GV/m can be sustained over these lengths. Laser-driven plasma accelerators now routinely produce monoenergetic, low divergence electron beams in the 100 MeV-1 GeV range, whereas electron-beam driven plasma accelerators have demonstrated the ability to double the energy of 42 GeV electrons using a high-energy collider beam in less than one meter. The development of this field is traced through a series of path breaking experiments.

Joshi, C. [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States)

2007-05-15

223

An Overview of Particle Beam Materials Processing Techniques*  

NASA Astrophysics Data System (ADS)

Materials processing techniques can lead to the development of new products, create new applications by modifying existing materials, and add significant value to existing product lines. Additionally, there is ever-increasing consumer and regulatory pressure to develop "greener" products utilizing "dry chemistry" which have reduced environmental impact, and where the production process yields only product and no waste. Such processing can result from the use of photons or elementary particles. Accelerated particle beams offer many diverse opportunities, to process materials if economic targets can be met. This mini-symposium, a joint endeavor of the APS Division of the Physics of Beams (DPB) and the Forum on Industrial and Applied Physics (FIAP), seeks to review these opportunities and the current state-of-the-art, by assembling leading practitioners of particle beam materials processing for review presentations. Beam processing areas covered in the symposium will include: electron beam processing of biomass, curing of composite materials, sterilization and other applications; ion beams and plasma accelerators for surface processing; proposed next-generation lithography tools that utilize either compact synchrotrons or small ion and electron accelerators; high-volume UV surface processing of polymers and metals using free-electron lasers or excimer lamps, and beam generation of tritium. * This work supported by U.S. DOE Contract No. DE-AC05-84ER40150.

Dylla, H. F.

1996-05-01

224

Neutral particle beams for space defense  

NASA Astrophysics Data System (ADS)

Neutral particle beam (NPB) weapons direct highly focused high energy streams of electrically neutral atomic particles traveling at nearly the speed of light, escaping deflection from the earth's magnetic field and acting on the subatomic structure of a target, destroying it from within. The beam's brief contact with a reentry vehicle produces a nuclear reaction in the latter that yields particle emissions; by detecting and identifying those particles, it becomes possible to effectively distinguish warheads from decoys. Attention is given to the NPB program roles to be played by the Beam Experiment Aboard Rocket and Neutral Particle Beam Integrated Space Experiment projects.

Botwin, Robert; Favale, Anthony

225

Neutral particle beams for space defense  

SciTech Connect

Neutral particle beam (NPB) weapons direct highly focused high energy streams of electrically neutral atomic particles traveling at nearly the speed of light, escaping deflection from the earth's magnetic field and acting on the subatomic structure of a target, destroying it from within. The beam's brief contact with a reentry vehicle produces a nuclear reaction in the latter that yields particle emissions; by detecting and identifying those particles, it becomes possible to effectively distinguish warheads from decoys. Attention is given to the NPB program roles to be played by the Beam Experiment Aboard Rocket and Neutral Particle Beam Integrated Space Experiment projects.

Botwin, R.; Favale, A.

1987-01-01

226

Seventy Five Years of Particle Accelerators  

SciTech Connect

Andy Sessler, Berkeley Lab director from 1973 to 1980, sheds light on the Lab's nearly eight-decade history of inventing and refining particle accelerators, which continue to illuminate the nature of the universe. His talk was presented July 26, 2006.

Andy Sessler

2008-03-04

227

Particle Acceleration in Stressed Coronal Magnetic Fields  

Microsoft Academic Search

This Letter presents an analysis of particle acceleration in a model of the complex magnetic field environment in the flaring solar corona. A slender flux tube, initially in hydrodynamic equilibrium, is stressed by random photospheric motions. A three-dimensional MHD code is used to follow the stochastic development of transient current sheets. These processes generate a highly fragmented electric field, through

R. Turkmani; L. Vlahos; K. Galsgaard; P. J. Cargill; H. Isliker

2005-01-01

228

Seventy Five Years of Particle Accelerators  

ScienceCinema

Andy Sessler, Berkeley Lab director from 1973 to 1980, sheds light on the Lab's nearly eight-decade history of inventing and refining particle accelerators, which continue to illuminate the nature of the universe. His talk was presented July 26, 2006.

Andy Sessler

2010-01-08

229

Seventy Five Years of Particle Accelerators  

ScienceCinema

Andy Sessler, Berkeley Lab director from 1973 to 1980, sheds light on the Lab's nearly eight-decade history of inventing and refining particle accelerators, which continue to illuminate the nature of the universe. His talk was presented July 26, 2006.

Andy Sessler

2013-06-11

230

Particle-beam-fusion progress report, July 1979 through December 1979  

SciTech Connect

The following chapters are included in this semi-annual progress report: (1) fusion target studies, (2) target experiments, (3) particle-beam source developments, (4) particle beam experiments, (5) pulsed power, (6) pulsed power applications, and (7) electron beam fusion accelerator project. (MOW)

Not Available

1981-01-01

231

Beam transport issues in high current linear accelerators  

SciTech Connect

Stable beam transport may be the limiting factor in the development of a new generation of high current linear induction accelerators. Several important beam stability topics, including radial oscillations induced by an accelerating gap, the diocotron, resistive wall, and cyclotron maser instabilities, and the transverse beam breakup and image displacement instabilities. At present image displacement appears to represent the most serious limitation to high current beam transport in linear accelerator structures. 13 refs.

Miller, R.B.; Poukey, J.W.; Epstein, B.G.; Shope, S.L.; Genoni, T.C.; Franz, M.; Godfrey, B.B.; Adler, R.J.; Mondelli, A.

1981-06-01

232

Neutral particle beam sensing and steering  

Microsoft Academic Search

The direction of a neutral particle beam (NPB) is determined by detecting Lyα radiation emitted during motional quenching of excited H(25) atoms in the beam during movement of the atoms through a magnetic field. At least one detector is placed adjacent the beam exit to define an optical axis that intercepts the beam at a viewing angle to include a

W. B. II Maier; D. D. Cobb; R. T. Robiscoe

1990-01-01

233

Neutral particle beam sensing and steering  

Microsoft Academic Search

The direction of a neutral particle beam (NPB) is determined by detecting Ly.alpha. radiation emitted during motional quenching of excited H(2S) atoms in the beam during movement of the atoms through a magnetic field. At least one detector is placed adjacent the beam exit to define an optical axis that intercepts the beam at a viewing angle to include a

II Maier; William B; Donald D. Cobb; Richard T. Robiscoe

1991-01-01

234

Stochastic particle acceleration by helical turbulence in solar flares  

NASA Astrophysics Data System (ADS)

Flaring release of magnetic energy in solar corona is only possible if the magnetic field deviates from a potential one. We show that the linear magnetohydrodynamic (MHD) modes excited on top of the non-potential magnetic field possess a non-zero kinetic helicity. Accordingly, this necessarily results in a noticeable kinetic helicity of the turbulence, composed of these linear modes with various scales and random phases, generated at the flare site by the primary energy release, which may be important for many applications. In particular, a non-zero turbulence helicity has a potentially strong effect on the particle acceleration because the helical component of the turbulence induces a mean regular large-scale (DC) electric field capable of directly accelerating the charged particles in addition to the commonly considered stochastic turbulent electric field. In this paper, we derive the kinetic helicity density of the linear MHD modes excited on top of a twisted large-scale magnetic field, estimate the corresponding turbulence helicity and take its effect on stochastic particle acceleration by the turbulence into consideration; in particular, we compare this induced mean electric field with the electron and estimated effective ion Dreicer fields. We have discovered that this, so far missing but highly important, ingredient of the turbulence at the flare site can be responsible for the thermal-to-non-thermal energy partition in flares by controlling the process of particle extraction from the thermal pool and formation of the seed particle population to be then stochastically accelerated to higher energies. In addition, it is naturally consistent with such puzzling flare manifestations as spatial separation of electron and proton emission sites, electron beam formation, and enrichment of the accelerated particle population by 3He and other rare ions.

Fleishman, Gregory D.; Toptygin, Igor N.

2013-03-01

235

ELIMED, future hadrontherapy applications of laser-accelerated beams  

NASA Astrophysics Data System (ADS)

Laser-ion acceleration has recently gained a great interest as an alternative to conventional and more expensive acceleration techniques. These ion beams have desirable qualities such as small source size, high luminosity and small emittance to be used in different fields as Nuclear Physics, Medical Physics, etc. This is very promising specially for the future perspective of a new concept of hadrontherapy based on laser-based devices could be developed, replacing traditional accelerating machines. Before delivering laser-driven beams for treatments they have to be handled, cleaned from unwanted particles and characterized in order to have the clinical requirements. In fact ion energy spectra have exponential trend, almost 100% energy spread and a wide angular divergence which is the biggest issue in the beam transport and, hence, in a wider use of this technology. In order to demonstrate the clinical applicability of laser-driven beams new collaboration between ELI-Beamlines project researchers from Prague (Cz) and a INFN-LNS group from Catania (I) has been already launched and scientists from different countries have already express their will in joining the project. This cooperation has been named ELIMED (MEDical application at ELIBeamlines) and will take place inside the ELI-Beamlines infrastructure located in Prague. This work describes the schedule of the ELIMED project and the design of the energy selector which will be realized at INFN-LNS. The device is an important part of the whole transport beam line which will be realised in order to make the ion beams suitable for medical applications.

Cirrone, Giuseppe A. P.; Carpinelli, Massimo; Cuttone, Giacomo; Gammino, Santo; Bijan Jia, S.; Korn, Georg; Maggiore, Mario; Manti, Lorenzo; Margarone, Daniele; Prokupek, Jan; Renis, Marcella; Romano, Francesco; Schillaci, Francesco; Tomasello, Barbara; Torrisi, Lorenzo; Tramontana, Antonella; Velyhan, Andriy

2013-12-01

236

Neutral particle beam intensity controller  

Microsoft Academic Search

The neutral beam intensity controller is based on selected magnetic defocusing of the ion beam prior to neutralization. The defocused portion of the beam is dumped onto a beam dump disposed perpendicular to the beam axis. Selective defocusing is occomplished by means of a magnetic field generator disposed about the neutralizer so that the field is transverse to the beam

W. K. Dagenhart

1984-01-01

237

Radio Frequency Station - Beam Dynamics Interaction in Circular Accelerators  

SciTech Connect

The longitudinal beam dynamics in circular accelerators is mainly defined by the interaction of the beam current with the accelerating Radio Frequency (RF) stations. For stable operation, Low Level RF (LLRF) feedback systems are employed to reduce coherent instabilities and regulate the accelerating voltage. The LLRF system design has implications for the dynamics and stability of the closed-loop RF systems as well as for the particle beam, and is very sensitive to the operating range of accelerator currents and energies. Stability of the RF loop and the beam are necessary conditions for reliable machine operation. This dissertation describes theoretical formalisms and models that determine the longitudinal beam dynamics based on the LLRF implementation, time domain simulations that capture the dynamic behavior of the RF station-beam interaction, and measurements from the Positron-Electron Project (PEP-II) and the Large Hadron Collider (LHC) that validate the models and simulations. These models and simulations are structured to capture the technical characteristics of the system (noise contributions, non-linear elements, and more). As such, they provide useful results and insight for the development and design of future LLRF feedback systems. They also provide the opportunity to study diverse longitudinal beam dynamics effects such as coupled-bunch impedance driven instabilities and single bunch longitudinal emittance growth. Coupled-bunch instabilities and RF station power were the performance limiting effects for PEP-II. The sensitivity of the instabilities to individual LLRF parameters, the effectiveness of alternative operational algorithms, and the possible tradeoffs between RF loop and beam stability were studied. New algorithms were implemented, with significant performance improvement leading to a world record current during the last PEP-II run of 3212 mA for the Low Energy Ring. Longitudinal beam emittance growth due to RF noise is a major concern for LHC. Simulations studies and measurements were conducted that clearly show the correlation between RF noise and longitudinal bunch emittance, identify the major LLRF noise contributions, and determine the RF component dominating this effect. With these results, LHC upgrades and alternative algorithms are evaluated to reduce longitudinal emittance growth during operations. The applications of this work are described with regard to future machines and analysis of new technical implementations, as well as to possible future work which would continue the directions of this dissertation.

Mastoridis, Themistoklis; /Stanford U., Elect. Eng. Dept. /SLAC

2011-03-01

238

Accelerator development for a radioactive beam facility based on ATLAS.  

SciTech Connect

The existing superconducting linac ATLAS is in many respects an ideal secondary beam accelerator for an ISOL (Isotope separator on-line) type radioactive beam facility. Such a facility would require the addition of two major accelerator elements: a low charge state injector for the existing heavy ion linac, and a primary beam accelerator providing 220 MV of acceleration for protons and light ions. Development work for both of these elements, including the option of superconducting cavities for the primary beam accelerator is discussed.

Shepard, K. W.

1998-01-08

239

Acceleration of particles by an active medium  

SciTech Connect

It is shown that an active medium can accelerate a single moving charge or a distribution of such charges. The acceleration is proportional to the population inversion and in the case of a single particle it is shown that it is inversely proportional to the spontaneous emission life-time. Simulation indicates that for the particular case presented, gradients in excess of 1 GV/m can develop. Unlike for laser applications, the spontaneous emission life-time has to be as short as possible. {copyright} 1995 {ital American Institute of Physics}.

Schaechter, L. [Electrical Engineering Department, Ben-Gurion University, Beer-Sheva 84105 (Israel)

1995-06-01

240

The effect of beam loading on the characteristics of an electron linear accelerator  

Microsoft Academic Search

The secondary field created by the moving bunches of particles in retarding structures is determined and the main properties of those features of electron linear accelerators which are sensitive to beam loading effects are analysed. A detailed discussion is given of the operation of a linear accelerator in the stationary and transitional regimes and also when it is loaded by

E. L. Burshtein; G. V. Voskresenskii

1963-01-01

241

Particle Accelerators for Radiotherapy:. Present Status and Future  

NASA Astrophysics Data System (ADS)

The paper describes the development of the application of particle accelerators in the treatment of cancer diseases over the past fifty years. Special emphasis is put on the routine application of conventional electron accelerators delivering electron and photon beams. This is the largest group of devices for radiotherapy (over 7500 machines operating worldwide). The number of patients reaches 5 million per year. The medical electron linacs have recently undergone considerable modifications of construction, in particular the systems of radiation field shaping. Contemporary accelerators for radiotherapy are equipped with multi-leaf collimators (MLC) which, in conjunction with IMRT (Intensity Modulation Radiation Therapy) technique and special system of therapy planning, assure considerably higher precision, effectiveness and quality of treatment.

Maciszewski, Wieslaw; Scharf, Waldemar

2004-07-01

242

Surfing Plasma Waves: A New Paradigm for Particle Accelerators  

NASA Astrophysics Data System (ADS)

Accelerator-based experiments have produced key breakthroughs in our understanding of the physical world. New accelerators, to explore the frontiers of Tera-scale Physics, appear possible, based on concepts developed over the last three decades in multi-disciplinary endeavors. The Plasma-Based Particle Accelerator is one concept that has made spectacular advances in the last few years. In this scheme, electrons or positrons gain energy by surfing the electric field of a plasma wave that is produced by the passage of an intense laser pulse or an electron beam through the plasma. This talk reviews the principles of this new technique and prognosticates how it is likely to impact science and technology in the future.

Joshi, Chandrashekhar

243

Transversal dynamics of relativistic charged particle beams  

NASA Astrophysics Data System (ADS)

The idea behind this work is to analyse the transversal dynamics of a relativistic charged particle beam. The beam is azimuthally symmetric, focused by a constant magnetic field and supposed initially cold. While mismatched, nonrelativistic and homogeneous beams oscillate with an invariant cold density profile, it is shown that relativistic homogeneous beams progressively heat and lose an important amount of constituents during its magnetic confinement. This heating process starts with phase-space wave breaking, a mechanism observed before in initially inhomogeneous beams. The results have been obtained with full self-consistent N -particle beam numerical simulations.

Nunes, R. P.; Rizzato, F. B.

2014-05-01

244

Linear particle accelerator with seal structure between electrodes and insulators  

DOEpatents

An electrostatic linear accelerator includes an electrode stack comprised of primary electrodes formed or Kovar and supported by annular glass insulators having the same thermal expansion rate as the electrodes. Each glass insulator is provided with a pair of fused-in Kovar ring inserts which are bonded to the electrodes. Each electrode is designed to define a concavo-convex particle trap so that secondary charged particles generated within the accelerated beam area cannot reach the inner surface of an insulator. Each insulator has a generated inner surface profile which is so configured that the electrical field at this surface contains no significant tangential component. A spark gap trigger assembly is provided, which energizes spark gaps protecting the electrodes affected by over voltage to prevent excessive energy dissipation in the electrode stack.

Broadhurst, John H. (Golden Valley, MN)

1989-01-01

245

Challenges in Accelerating and Colliding Polarized Beams (455th Brookhaven Lecture)  

ScienceCinema

At the Relativistic Heavy Ion Collider (RHIC), scientists are investigating not only the primordial properties of the universe but also another fundamental question of particle physics: the property of "spin." A particle's spin comes from its intrinsic angular momentum and is a basic property such as charge or mass. Many existing and future high energy and nuclear physics experiments rely on accessing spin. These experiments require using beams of polarized particles, which have their spins all pointing in one direction. When used as a probe of matter, beams of polarized particles reveal details of fundamental interactions not accessible with unpolarized particles. Experiments using polarized beams also need accelerators capable of accelerating and colliding such beams while preserving polarization. Achieving this, as in so many extraordinary feats that make science discoveries possible, is easier said than done.

246

Proceedings of the 1997 Particle Accelerator Conference Held in Vancouver, B.C., Canada on 12-16 May 1997. Volume 2: Beam Dynamics, Instrumentation and Controls.  

National Technical Information Service (NTIS)

The Proceedings contains 1261 papers presented at PAC'97, held in Vancouver in May, 1997. With one third of the 1221 delegates coming from 23 countries outside North America, these papers present a comprehensive picture of accelerator science, technology ...

J. Thomson M. Comyn M. Reiser M. K. Craddock

1997-01-01

247

Naked singularities as particle accelerators. II  

SciTech Connect

We generalize here our earlier results on particle acceleration by naked singularities. We showed recently [M. Patil and P. S. Joshi, Phys. Rev. D 82, 104049 (2010).] that the naked singularities that form due to the gravitational collapse of massive stars provide a suitable environment where particles could get accelerated and collide at arbitrarily high center-of-mass energies. However, we focused there only on the spherically symmetric gravitational collapse models, which were also assumed to be self-similar. In this paper, we broaden and generalize the result to all gravitational collapse models leading to the formation of a naked singularity as the final state of collapse, evolving from a regular initial data, without making any prior restrictive assumptions about the spacetime symmetries such as above. We show that, when the particles interact and collide near the Cauchy horizon, the energy of collision in the center-of-mass frame will be arbitrarily high, thus offering a window to the Planck scale physics. We also consider the issue of various possible physical mechanisms of generation of such very high-energy particles from the vicinity of naked singularity. We then construct a model of gravitational collapse to a timelike naked singularity to demonstrate the working of these ideas, where the pressure is allowed to be negative, but the energy conditions are respected. We show that a finite amount of mass-energy density has to be necessarily radiated away from the vicinity of the naked singularity as the collapse evolves. Therefore, the nature of naked singularities, both at the classical and quantum level, could play an important role in the process of particle acceleration, explaining the occurrence of highly energetic outgoing particles in the vicinity of the Cauchy horizon that participate in extreme high-energy collisions.

Patil, Mandar; Joshi, Pankaj S.; Malafarina, Daniele [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India)

2011-03-15

248

Proceedings of: 2005 Particle Acceleration Confence  

SciTech Connect

The 21st Particle Accelerator Conference, PAC05, took place at the Knoxville Convention Center (KCC) from Monday through Friday, May 16-20, 2005. Sponsored by the American Physical Society (APS), the Institute of Electrics and Electronics Engineers (IEEE) with its subdivision of Nuclear and Plasma Sciences Society (NPSS), the conference was hosted by the Oak Ridge National Laboratory (ORNL) Spallation Neutron Source (SNS) Project and Thomas Jefferson National Accelerator Facility (JLab). The conference was chaired by Norbert Holtkamp, and the Local Organizing Committee was made up of staff from the ORNL SNS Project under the chairmanship of Stuart Henderson. The conference welcomed over 1400 delegates from the United States, Europe, Asia, the Middle East, South America and from as far away as Australia. Almost 1400 papers where processed during the conference and will be published on the Joint Accelerator Conferences Website (JACoW) page.

Henderson, Stuart

2006-01-01

249

Beam profile effects on NPB (neutral particle beam) performance  

Microsoft Academic Search

A comparison of neutral particle beam brightness for various neutral beam profiles indicates that the widely used assumption of a Gaussian profile may be misleading for collisional neutralizers. An analysis of available experimental evidence shows that lower peaks and higher tails, compared to a Gaussian beam profile, are observed out of collisional neutralizers, which implies that peak brightness is over

LeClaire; R. J. Jr

1988-01-01

250

FASTBUS for the particle accelerator laboratories  

NASA Astrophysics Data System (ADS)

The FASTBUS modular high speed data acquisition and control system for high energy physics and other applications was described by Costrell and Dawson at the 1983 Particle Accelerator Conference. Both the specification and the implementation of this interlaboratory development have progressed considerably since that time. Because of its many attractive features, FASTBUS is currently in use in several major nuclear and high energy physics laboratories and is also finding application in other areas.

Dawson, W. K.; Costrell, L.; Ikeda, H.; Ponting, P. J.; Walz, H. V.

1985-05-01

251

Particle acceleration during substorm growth and onset  

Microsoft Academic Search

The authors present ISEE-1 observations of ion and electron energization made at â¼11 R{sub E} during a substorm event occurring on 2 April 1978. An analysis of the dominant cross-tail current systems in this event has allowed them to uniquely associate particle energization processes with the development and\\/or disruption of the cross-tail currents. They find that significant ion acceleration occurs

D. J. Williams; D. G. Mitchell; C. Y. Huang; L. A. Frank; C.T. Russell

1990-01-01

252

Levy-Student distributions for halos in accelerator beams  

SciTech Connect

We describe the transverse beam distribution in particle accelerators within the controlled, stochastic dynamical scheme of stochastic mechanics (SM) which produces time reversal invariant diffusion processes. This leads to a linearized theory summarized in a Schroedinger-like (SL) equation. The space charge effects have been introduced in recent papers by coupling this S-L equation with the Maxwell equations. We analyze the space-charge effects to understand how the dynamics produces the actual beam distributions, and in particular we show how the stationary, self-consistent solutions are related to the (external and space-charge) potentials both when we suppose that the external field is harmonic (constant focusing), and when we a priori prescribe the shape of the stationary solution. We then proceed to discuss a few other ideas by introducing generalized Student distributions, namely, non-Gaussian, Levy infinitely divisible (but not stable) distributions. We will discuss this idea from two different standpoints: (a) first by supposing that the stationary distribution of our (Wiener powered) SM model is a Student distribution; (b) by supposing that our model is based on a (non-Gaussian) Levy process whose increments are Student distributed. We show that in the case (a) the longer tails of the power decay of the Student laws and in the case (b) the discontinuities of the Levy-Student process can well account for the rare escape of particles from the beam core, and hence for the formation of a halo in intense beams.

Cufaro Petroni, Nicola; De Martino, Salvatore; De Siena, Silvio; Illuminati, Fabrizio [Dipartimento di Matematica dell'Universita di Bari and INFN Sezione di Bari, via E. Orabona 4, 70125 Bari (Italy); Dipartimento di Fisica dell'Universita di Salerno, INFM Unita di Salerno, and INFN Sezione di Napoli Gruppo collegato di Salerno, Via S. Allende, I-84081 Baronissi (Saudi Arabia) (Italy)

2005-12-15

253

Lévy-Student distributions for halos in accelerator beams.  

PubMed

We describe the transverse beam distribution in particle accelerators within the controlled, stochastic dynamical scheme of stochastic mechanics (SM) which produces time reversal invariant diffusion processes. This leads to a linearized theory summarized in a Schrödinger-like (SL) equation. The space charge effects have been introduced in recent papers by coupling this S-L equation with the Maxwell equations. We analyze the space-charge effects to understand how the dynamics produces the actual beam distributions, and in particular we show how the stationary, self-consistent solutions are related to the (external and space-charge) potentials both when we suppose that the external field is harmonic (constant focusing), and when we a priori prescribe the shape of the stationary solution. We then proceed to discuss a few other ideas by introducing generalized Student distributions, namely, non-Gaussian, Lévy infinitely divisible (but not stable) distributions. We will discuss this idea from two different standpoints: (a) first by supposing that the stationary distribution of our (Wiener powered) SM model is a Student distribution; (b) by supposing that our model is based on a (non-Gaussian) Lévy process whose increments are Student distributed. We show that in the case (a) the longer tails of the power decay of the Student laws and in the case (b) the discontinuities of the Lévy-Student process can well account for the rare escape of particles from the beam core, and hence for the formation of a halo in intense beams. PMID:16486070

Cufaro Petroni, Nicola; De Martino, Salvatore; De Siena, Silvio; Illuminati, Fabrizio

2005-12-01

254

Accelerating in the Future: Lasers Start to Produce Quality High Energy Electron Beams  

ScienceCinema

Twenty-five years ago, a new method was proposed for the acceleration of electrons to high energies using lasers. The simplest implementation of a so-called laser wakefield accelerator involves sending an intense laser pulse through a gas to ionize it and form a plasma of dissociated electrons and ions. The radiation pressure of the laser pushes the plasma electrons aside, creating a density modulation, or 'wake'. This changing electron density can result in fields that accelerate particles thousands of times more strongly than in conventional machines, accelerating electrons to high energies in short distances. The compactness of these accelerators would allow higher energies for the frontiers of fundamental physics and make clinical and laboratory applications of accelerators practical. In work that brings the promise of laser-driven particle accelerators dramatically closer to reality, we have produced high-quality electron beams in a plasma channel based accelerating structure akin to an optical fiber of only a few millimeters long.

255

Channeled particle acceleration by plasma waves in metals  

SciTech Connect

A solid state accelerator concept utilizing particle acceleration along crystal channels by longitudinal electron plasma waves in a metal is presented. Acceleration gradients of order 100 GV/cm are theoretically possible. Particle dechanneling due to electron multiple scattering can be eliminated with a sufficiently high acceleration gradient. Plasma wave dissipation and generation in metals are also discussed.

Chen, P.; Noble, R.J.

1987-01-01

256

Aerodynamic beam generator for large particles  

DOEpatents

A new type of aerodynamic particle beam generator is disclosed. This generator produces a tightly focused beam of large material particles at velocities ranging from a few feet per second to supersonic speeds, depending on the exact configuration and operating conditions. Such generators are of particular interest for use in additive fabrication techniques.

Brockmann, John E. (Albuquerque, NM); Torczynski, John R. (Albuquerque, NM); Dykhuizen, Ronald C. (Albuquerque, NM); Neiser, Richard A. (Albuquerque, NM); Smith, Mark F. (Albuquerque, NM)

2002-01-01

257

Neutral particle beam discrimination and lethality  

Microsoft Academic Search

Using, or possibly just developing, neutral particle beams (NPBs) to both discriminate decoys and kill weapons could induce 10-fold reductions in each. The conventional factor of two'' increase in the time required to do both does not capture particle beams' impact. They could reduce the threat to â1 reentry vehicle (RV) plus â10 decoys per heavy missile, which could be

G. H. Canavan; J. C. Browne

1991-01-01

258

Neutral particle beams for space defense  

Microsoft Academic Search

Neutral particle beam (NPB) weapons direct highly focused high energy streams of electrically neutral atomic particles traveling at nearly the speed of light, escaping deflection from the earth's magnetic field and acting on the subatomic structure of a target, destroying it from within. The beam's brief contact with a reentry vehicle produces a nuclear reaction in the latter that yields

Robert Botwin; Anthony Favale

1987-01-01

259

Neutral particle beam sensing and steering  

Microsoft Academic Search

The direction of a neutral particle beam (NPB) is determined by detecting Lya radiation emitted during motional quenching of excited H(2S) atoms in the beam during movement of the atoms through a magnetic exit to define an optical axis that intercepts the beam at a viewing angle to include a volume generating a selected number of photons for detection. The

W. B. Maier; D. D. Cobb; R. T. Robiscoe

1991-01-01

260

Linear accelerator in the space: The beam experiment aboard rocket.  

National Technical Information Service (NTIS)

On July 13, 1989 the BEAM experiment Aboard Rocket (BEAR) linear accelerator was successfully launched and operated in space. The flight demonstrated that a neutral hydrogen beam could be successfully propagated in an exoatmospheric environment. The accel...

P. G. O'Shea T. A. Butler M. T. Lynch K. F. McKenna M. B. Pongratz

1990-01-01

261

Cryogenic Pump with a Long Continuous Run Without Filling Intended for a Particle Accelerator.  

National Technical Information Service (NTIS)

A cryogenic pump is described, specially designed to be used in an electrostatic particle accelerator. The same tubular liquid helium bath provides pumping in the accelerating tube and around the beam. The temperature of the bath can be adjusted between 2...

F. Bottiglioni J. Coutant M. Fois R. Duthil J. C. Gelebart

1977-01-01

262

Electrostatic plasma lens for focusing negatively charged particle beams  

SciTech Connect

We describe the current status of ongoing research and development of the electrostatic plasma lens for focusing and manipulating intense negatively charged particle beams, electrons, and negative ions. The physical principle of this kind of plasma lens is based on magnetic isolation electrons providing creation of a dynamical positive space charge cloud in shortly restricted volume propagating beam. Here, the new results of experimental investigations and computer simulations of wide-aperture, intense electron beam focusing by plasma lens with positive space charge cloud produced due to the cylindrical anode layer accelerator creating a positive ion stream towards an axis system is presented.

Goncharov, A. A.; Dobrovolskiy, A. M.; Dunets, S. M. [Institute of Physics NAS of Ukraine, Kiev 03028, Ave. Nauki 46 (Ukraine); Litovko, I. V. [Institute for Nuclear Research NAS of Ukraine, Kiev 03650, pr. Nauki 47 (Ukraine); Gushenets, V. I.; Oks, E. M. [High-Current Electronics Institute SB of RAS, Tomsk (Russian Federation)

2012-02-15

263

Apparatus for measuring charged particle beam  

NASA Technical Reports Server (NTRS)

An apparatus to measure the incident charged particle beam flux while effectively eliminating losses to reflection and/or secondary emission of the charged particle beam being measured is described. It comprises a sense cup through which the charged particle beam enters. A sense cone forms the rear wall of the interior chamber with the cone apex adjacent the entry opening. An outer case surrounds the sense cup and is electrically insulated therefrom. Charged particles entering the interior chamber are trapped and are absorbed by the sense cup and cone and travel through a current measuring device to ground.

Gregory, D. A.; Stocks, C. D. (inventors)

1984-01-01

264

Particle acceleration in relativistic subluminal shock environments  

NASA Astrophysics Data System (ADS)

The understanding of the particle spectra resulting from acceleration in relativistic shocks as they occur in extragalactic sources is essential for the interpretation of the Cosmic Ray spectrum above the ankle (E>3*1e18 eV). It is believed that extragalactic sources like Active Galactic Nuclei and Gamma Ray Bursts can produce particle spectra up to E~1e21 eV. In this contribution, subluminal shocks are investigated with respect to different shock boost factors Gamma and the inclination angle between the shock normal and the magnetic field psi. A correlation between the boost factor and the spectral behavior of the emitted particles is found. The results are compared to Gamma Ray Burst observations and the Cosmic Ray spectrum at the highest energies.

Meli, A.; Becker, J. K.; Quenby, J. J.; et al.

265

EFFECT OF DARK CURRENTS ON THE ACCELERATED BEAM IN AN X-BAND LINAC  

Microsoft Academic Search

X-band accelerating structures operate at surface gradients up to 120-180 MV\\/m. At these gradients, electron currents are emitted spontaneously from the structure walls (''dark currents'') and generate additional electromagnetic fields inside the structure. The authors estimate the effect of these fields on the accelerated beam in a linac using two methods: a particle-in-cell simulation code MAGIC and a particle tracking

V. A. Dolgashev; K. L. F. Bane; J. Wu; G. V. Stupakov; T. Raubenheimer

2004-01-01

266

Radiation Safety System for SPIDER Neutral Beam Accelerator  

SciTech Connect

SPIDER (Source for Production of Ion of Deuterium Extracted from RF Plasma only) and MITICA (Megavolt ITER Injector Concept Advanced) are the ITER neutral beam injector (NBI) testing facilities of the PRIMA (Padova Research Injector Megavolt Accelerated) Center. Both injectors accelerate negative deuterium ions with a maximum energy of 1 MeV for MITICA and 100 keV for SPIDER with a maximum beam current of 40 A for both experiments. The SPIDER facility is classified in Italy as a particle accelerator. At present, the design of the radiation safety system for the facility has been completed and the relevant reports have been presented to the Italian regulatory authorities. Before SPIDER can operate, approval must be obtained from the Italian Regulatory Authority Board (IRAB) following a detailed licensing process. In the present work, the main project information and criteria for the SPIDER injector source are reported together with the analysis of hypothetical accidental situations and safety issues considerations. Neutron and photon nuclear analysis is presented, along with special shielding solutions designed to meet Italian regulatory dose limits. The contribution of activated corrosion products (ACP) to external exposure of workers has also been assessed. Nuclear analysis indicates that the photon contribution to worker external exposure is negligible, and the neutron dose can be considered by far the main radiation protection issue. Our results confirm that the injector has no important radiological impact on the population living around the facility.

Sandri, S.; Poggi, C. [ENEA, Radiation Protection Institute, IRP-FUAC, Frascati (Italy); Coniglio, A. [Medical Physics Department, S. Giovanni Calibita Hospital, Fatebenefratelli, Isola Tiberina, Roma (Italy); D'Arienzo, M. [ENEA, Ionizing Radiation Metrology National Institute, METR, Casaccia, Rome (Italy)

2011-12-13

267

Radiation Safety System for SPIDER Neutral Beam Accelerator  

NASA Astrophysics Data System (ADS)

SPIDER (Source for Production of Ion of Deuterium Extracted from RF Plasma only) and MITICA (Megavolt ITER Injector Concept Advanced) are the ITER neutral beam injector (NBI) testing facilities of the PRIMA (Padova Research Injector Megavolt Accelerated) Center. Both injectors accelerate negative deuterium ions with a maximum energy of 1 MeV for MITICA and 100 keV for SPIDER with a maximum beam current of 40 A for both experiments. The SPIDER facility is classified in Italy as a particle accelerator. At present, the design of the radiation safety system for the facility has been completed and the relevant reports have been presented to the Italian regulatory authorities. Before SPIDER can operate, approval must be obtained from the Italian Regulatory Authority Board (IRAB) following a detailed licensing process. In the present work, the main project information and criteria for the SPIDER injector source are reported together with the analysis of hypothetical accidental situations and safety issues considerations. Neutron and photon nuclear analysis is presented, along with special shielding solutions designed to meet Italian regulatory dose limits. The contribution of activated corrosion products (ACP) to external exposure of workers has also been assessed. Nuclear analysis indicates that the photon contribution to worker external exposure is negligible, and the neutron dose can be considered by far the main radiation protection issue. Our results confirm that the injector has no important radiological impact on the population living around the facility.

Sandri, S.; Coniglio, A.; D'Arienzo, M.; Poggi, C.

2011-12-01

268

Full counting statistics of stationary particle beams  

NASA Astrophysics Data System (ADS)

We present a general theoretical framework for treating particle beams as time-stationary limits of many particle systems. Due to stationarity, the total particle number diverges, and a description in Fock space is no longer possible. Nevertheless, we show that when describing the particle detection via second quantized arrival time observables, such beams exhibit a well-defined ``local'' counting statistics, that is, full counting statistics of all clicks falling into any given finite time interval. We also treat in detail a realization of such a beam via the long time limit of a source creating particles in a fixed initial state from which they then evolve freely. From the mathematical point of view, the beam is described by a quasi-free state which, in the one-particle level, is locally trace class with respect to the operator valued measure describing the time observable; this ensures the existence of a Fredholm determinant defining the characteristic function of the counting statistics.

Kiukas, J.; Ruschhaupt, A.; Werner, R. F.

2013-04-01

269

Beam energy scaling of a stably operated laser wakefield accelerator  

SciTech Connect

Two-dimensional particle-in-cell simulations were performed to demonstrate the fluctuation of the maximum beam energy while varying the plasma density in a laser wakefield accelerator (LWFA) under the transition from mildly relativistic regime to relativistic regime. The fluctuation of the beam energy is induced by the unstable accelerating structure, which length is dynamically oscillating between the plasma wavelength and the relativistic plasma wavelength. The simulation results also reveal the existence of the parameter space for the stable operation of a LWFA. An empirical formulation was derived by the curve fitting of the simulated radius of curvature of the returning electrons along the boundary of the plasma bubble in a stably operated LWFA. The comparisons between the energy scaling law derived from the empirical formulation, the two-dimensional and three-dimensional PIC simulations, and previous experimental results with self-guided laser pulses show good agreement. The scaling law derived in the study can provide a correct estimation of the maximum beam energy for a newly designed LWFA experiment with an optimal configuration of the laser pulse.

Chen, S. H.; Lin-Liu, Y. R. [Department of Physics, National Central University, Jhongli 32001, Taiwan (China); Tai, L. C. [Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Liu, C. S. [Department of Physics, University of Maryland, College Park, Maryland 20742 (United States)

2010-06-15

270

Beam loading in a laser-plasma accelerator using a near-hollow plasma channel  

SciTech Connect

Beam loading in laser-plasma accelerators using a near-hollow plasma channel is examined in the linear wake regime. It is shown that, by properly shaping and phasing the witness particle beam, high-gradient acceleration can be achieved with high-efficiency, and without induced energy spread or emittance growth. Both electron and positron beams can be accelerated in this plasma channel geometry. Matched propagation of electron beams can be achieved by the focusing force provided by the channel density. For positron beams, matched propagation can be achieved in a hollow plasma channel with external focusing. The efficiency of energy transfer from the wake to a witness beam is calculated for single ultra-short bunches and bunch trains.

Schroeder, C. B.; Benedetti, C.; Esarey, E.; Leemans, W. P. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2013-12-15

271

On acceleration of particles trapped in the potential trough of the beat of two waves  

Microsoft Academic Search

In inhomogeneous plasma systems, the beat of two waves can change the velocity of propagation. The authors discuss the possibility of the acceleration of particles trapped in the beat potential trough of these waves. Two waves, forming the beat, can be excited, e.g. by means of the beam-plasma interaction. Estimations of the maximum ion energy and of the ion beam

L. Krlin

1982-01-01

272

Report on the possible benefits of using high-temperature superconductor materials in particle-accelerator design. Final report, June-September 1987  

SciTech Connect

This report discusses different design concepts for particle-beam accelerators. It demonstrates that with the use of high-temperature superconducting materials, a more-compact, lighter, and more-robust accelerator design can be realized for the space-based neutral particle beam (NPB) accelerator.

Cohen, L.; Collins, R.; Balko, B.

1988-12-01

273

Laser ion acceleration toward future ion beam cancer therapy - Numerical simulation study -  

PubMed Central

Background: Ion beam has been used in cancer treatment, and has a unique preferable feature to deposit its main energy inside a human body so that cancer cell could be killed by the ion beam. However, conventional ion accelerator tends to be huge in its size and its cost. In this paper a future intense-laser ion accelerator is proposed to make the ion accelerator compact. Subjects and methods: An intense femtosecond pulsed laser was employed to accelerate ions. The issues in the laser ion accelerator include the energy efficiency from the laser to the ions, the ion beam collimation, the ion energy spectrum control, the ion beam bunching and the ion particle energy control. In the study particle computer simulations were performed to solve the issues, and each component was designed to control the ion beam quality. Results: When an intense laser illuminates a target, electrons in the target are accelerated and leave from the target; temporarily a strong electric field is formed between the high-energy electrons and the target ions, and the target ions are accelerated. The energy efficiency from the laser to ions was improved by using a solid target with a fine sub-wavelength structure or by a near-critical density gas plasma. The ion beam collimation was realized by holes behind the solid target. The control of the ion energy spectrum and the ion particle energy, and the ion beam bunching were successfully realized by a multi-stage laser-target interaction. Conclusions: The present study proposed a novel concept for a future compact laser ion accelerator, based on each component study required to control the ion beam quality and parameters.

Kawata, Shigeo; Izumiyama, Takeshi; Nagashima, Toshihiro; Takano, Masahiro; Barada, Daisuke; Kong, Qing; Gu, Yan Jun; Wang, Ping Xiao; Ma, Yan Yun; Wang, Wei Min

2013-01-01

274

Particle drift, diffusion, and acceleration at shocks  

NASA Technical Reports Server (NTRS)

The gradient and curvature drifts implicit in change of the ambient magnetic field at a hydromagnetic shock wave are incorporated into the diffusive theory of shock acceleration of charged particles. The conventional jump condition at the shock is modified by a term incorporating the large drift along the shock plane. This term vanished identically for one-dimensional systems, but must be included in general for shocks which are finite in transverse extent or which have transverse structure. It is found that the effect of the drift is such that the transverse drift rate is proportional to the acceleration rate, and for perpendicular shocks is exactly equal to the rate of change of energy in the V x B electric field observed in the shock frame. This establishes a connection with the 'shock drift' models which neglect diffusion.

Jokipii, J. R.

1982-01-01

275

Detecting chaos in particle accelerators through the frequency map analysis method.  

PubMed

The motion of beams in particle accelerators is dominated by a plethora of non-linear effects, which can enhance chaotic motion and limit their performance. The application of advanced non-linear dynamics methods for detecting and correcting these effects and thereby increasing the region of beam stability plays an essential role during the accelerator design phase but also their operation. After describing the nature of non-linear effects and their impact on performance parameters of different particle accelerator categories, the theory of non-linear particle motion is outlined. The recent developments on the methods employed for the analysis of chaotic beam motion are detailed. In particular, the ability of the frequency map analysis method to detect chaotic motion and guide the correction of non-linear effects is demonstrated in particle tracking simulations but also experimental data. PMID:24985466

Papaphilippou, Yannis

2014-06-01

276

Neutron dosimetry in high energy X-ray beams of medical accelerators  

Microsoft Academic Search

High energy X-ray beams from medical accelerators are used in cancer therapy. In such beams, neutrons are also produced due to photon-neutron interactions in the target materials, collimator and beam flattening filter. The feasibility of employing fast-neutron-induced recoil particle tracks in polycarbonate foils developed by the electrochemical etching (ECE) method for the dosimetry of such neutrons was investigated. The experiments

M. Sohrabi; K. Z. Morgan

1979-01-01

277

Computer modeling of test particle acceleration at oblique shocks  

Microsoft Academic Search

We review the basic techniques and results of numerical codes used to model the acceleration of charged particles at oblique, fast-mode, collisionless shocks. The emphasis is upon models in which accelerated particles (ions) are treated as test particles, and particle dynamics is calculated by numerically integrating along exact phase-space orbits. We first review the case where ions are sufficiently energetic

Robert B. Decker

1988-01-01

278

The model of the gap of acceleration of intense electron beams in plasma sources of the charged particles with ionization of residual gas  

Microsoft Academic Search

Sources of charged particles with plasma emitter represent a complicated problem because it is necessary to take into account that position and form of the emitting plasma surfaces self-coordinated with distribution of the potential (i.e. the plasma surfaces must be set in point where zero strength of the electric field is established). In this paper the algorithm of mathematical modeling

O. N. Petrovich; A. F. Stekolnikov; V. A. Gruzdev

2002-01-01

279

Laser Plasma Particle Accelerators: Large Fields for Smaller Facility Sources  

SciTech Connect

Compared to conventional particle accelerators, plasmas can sustain accelerating fields that are thousands of times higher. To exploit this ability, massively parallel SciDAC particle simulations provide physical insight into the development of next-generation accelerators that use laser-driven plasma waves. These plasma-based accelerators offer a path to more compact, ultra-fast particle and radiation sources for probing the subatomic world, for studying new materials and new technologies, and for medical applications.

Geddes, Cameron G.R.; Cormier-Michel, Estelle; Esarey, Eric H.; Schroeder, Carl B.; Vay, Jean-Luc; Leemans, Wim P.; Bruhwiler, David L.; Cary, John R.; Cowan, Ben; Durant, Marc; Hamill, Paul; Messmer, Peter; Mullowney, Paul; Nieter, Chet; Paul, Kevin; Shasharina, Svetlana; Veitzer, Seth; Weber, Gunther; Rubel, Oliver; Ushizima, Daniela; Bethel, Wes; Wu, John

2009-03-20

280

Particle Acceleration and Propagation in Strong Flares without Major Solar Energetic Particle Events  

NASA Astrophysics Data System (ADS)

Solar energetic particles (SEPs) detected in space are statistically associated with flares and coronal mass ejections (CMEs). But it is not clear how these processes actually contribute to the acceleration and transport of the particles. The present work addresses the question why flares accompanied by intense soft X-ray bursts may not produce SEPs detected by observations with the GOES spacecraft. We consider all X-class X-ray bursts between 1996 and 2006 from the western solar hemisphere. 21 out of 69 have no signature in GOES proton intensities above 10 MeV, despite being significant accelerators of electrons, as shown by their radio emission at cm wavelengths. The majority (11/20) has no type III radio bursts from electron beams escaping towards interplanetary space during the impulsive flare phase. Together with other radio properties, this indicates that the electrons accelerated during the impulsive flare phase remain confined in the low corona. This occurs in flares with and without a CME. Although GOES saw no protons above 10 MeV at geosynchronous orbit, energetic particles were detected in some (4/11) confined events at Lagrangian point L1 aboard ACE or SoHO. These events have, besides the confined microwave emission, dm-m wave type II and type IV bursts indicating an independent accelerator in the corona. Three of them are accompanied by CMEs. We conclude that the principal reason why major solar flares in the western hemisphere are not associated with SEPs is the confinement of particles accelerated in the impulsive phase. A coronal shock wave or the restructuring of the magnetically stressed corona, indicated by the type II and IV bursts, can explain the detection of SEPs when flare-accelerated particles do not reach open magnetic field lines. But the mere presence of these radio signatures, especially of a metric type II burst, is not a sufficient condition for a major SEP event.

Klein, K.-L.; Trottet, G.; Samwel, S.; Malandraki, O.

2011-04-01

281

Particle acceleration by electromagnetic ion cyclotron turbulence  

NASA Technical Reports Server (NTRS)

The LF EM-turbulence which furnishes energy for the acceleration of ions in various regions of the earth's magnetosphere efficiently accomplishes its transfer of energy from waves to particles through ion cyclotron resonance (ICR) with the left-hand polarized component of the turbulence; the result of this interaction is a heating of the particle distribution. A general theoretical treatment of ICR heating in a weakly inhomogeneous magnetic geometry is presented, en route to a more detailed examination of auroral ion conics' formation. A substantial simplification of the analysis of the altitude-asymptotic form of the conic distribution is obtained via the similarity transformation introduced into the properties of the electric field spectral density and the earth's dipolar magnetic field.

Crew, G. B.; Chang, Tom

1990-01-01

282

Spallation nucleosynthesis by accelerated charged-particles  

NASA Astrophysics Data System (ADS)

Recent observations have suggested the presence of radioactive elements, such as Pm and 84<=Z<=99 elements) at the surface of the magnetic star HD101065, also known as Przybylski's star. This star is know to be a chemically peculiar star and its anomalous 38acceleration of charged-particles, mainly protons and ?-particles, that in turn can by interaction with the stellar material modify the surface content. The present contribution explores to what extent the spallation processes resulting from the interaction of the stellar material with stellar energetic particle can by themselves only explain the abundances determined by observation at the surface of HD101065. We show that specific parametric simulations can explain many different observational aspects, and in particular that a significant production of Z>30 heavy elements can be achieved. In this nucleosynthesis process, the secondary-neutron captures play a crucial role. The most attractive feature of the spallation process is the systematic production of Pm and Tc and the possible synthesis of actinides and sub-actinides. Based on such a parametric model, it is also shown that intense fluences of accelerated charged-particles interacting with surrounding material can efficiently produce elements heavier than iron. Different regimes are investigated and shown to be at the origin of p- and s-nuclei in the case of high-fluence low-flux events and r-nuclei for high-fluence high-flux irradiations. The possible existence of such irradiation events need to be confirmed by hydrodynamics simulations, but most of all by spectroscopic observations through the detection of short-lived radio-elements.

Goriely, S.

2008-05-01

283

Beam collimation and transport of laser-accelerated protons by a solenoid field  

NASA Astrophysics Data System (ADS)

A pulsed high field solenoid was used in a laser-proton acceleration experiment to collimate and transport the proton beam that was generated at the irradiation of a flat foil by a high intensity laser pulse. 1012 particles at an energy of 2.3 MeV could be caught and transported over a distance of more than 240 mm. Strong space charge effects occur, induced by the high field of the solenoid that forces all co-moving electrons down the the solenoid's axis, building up a strong negative space charge that interacts with the proton beam. This leads to an aggregation of the proton beam around the solenoid's axis and therefore to a stronger focusing effect. The collimation and transport of laser-accelerated protons is the first step to provide these unique beams for further applications like post-acceleration by conventional accelerator structures.

Harres, K.; Alber, I.; Tauschwitz, A.; Bagnoud, V.; Daido, H.; Günther, M.; Nürnberg, F.; Otten, A.; Schollmeier, M.; Schütrumpf, J.; Tampo, M.; Roth, M.

2010-08-01

284

Simplified Charged Particle Beam Transport Modeling Using Commonly Available Commercial Software.  

National Technical Information Service (NTIS)

Particle beam modeling in accelerators has been the focus of considerable effort since the 1950s. Many generations of tools have resulted from this process, each leveraging both prior experience and increases in computer power. However, continuing innovat...

D. Douglas J. Eldred K. Beard L. Osborne P. Evtushenko

2007-01-01

285

Plasma diagnostic techniques using particle beam probes  

SciTech Connect

A brief overview is given of particle beam probing. The fundamental concepts common to all techniques are discussed as well as the design considerations for choosing a particular diagnostic technique. The capabilities of existing and proposed techniques, and the present status of the techniques in major magnetic confinement geometries is also presented. Techniques which involve the injection of a beam of neutral particles into the plasma are then considered. The techniques of beam attenuation, beam scattering, and active charge exchange using a beam of light particles such as hydrogen or helium are first presented. Optical measurements of the Zeeman splitting of the radiation from a neutral lithium beam is then discussed, including a new proposal for significantly improving this technique through the addition of a dye laser. Two techniques involving the injection of heavy neutral particles are then presented, and the section concludes with two proposed techniques for measuring the properties of the alpha particles produced from actual fusion reactions. The diagnostic techniques which are based upon the injection of a beam of charged particles into the plasma are next described. The advantages and limitations of these techniques in comparison with the neutral techniques are discussed, followed by a description of specific techniques.

Jennings, W C

1980-07-01

286

Self-accelerating optical beams in highly nonlocal nonlinear media.  

PubMed

We find self-accelerating beams in highly nonlocal nonlinear optical media, and show that their propagation dynamics is strongly affected by boundary conditions. Specifically for the thermal optical nonlinearity, the boundary conditions have a strong impact on the beam trajectory: they can increase the acceleration during propagation, or even cause beam bending in a direction opposite to the initial trajectory. Under strong self-focusing, the accelerating beam decomposes into a localized self-trapped beam propagating on an oscillatory trajectory and a second beam which accelerates in a different direction. We augment this study by investigating the effects caused by a finite aperture and by a nonlinear range of a finite extent. PMID:22109397

Bekenstein, Rivka; Segev, Mordechai

2011-11-21

287

Induced radioactivity in and around high-energy particle accelerators.  

PubMed

Particle accelerators and their surroundings are locations of residual radioactivity production that is induced by the interaction of high-energy particles with matter. This paper gives an overview of the principles of activation caused at proton accelerators, which are the main machines operated at Conseil Européen pour la Recherche Nucléaire. It describes the parameters defining radio-nuclide production caused by beam losses. The second part of the paper concentrates on the analytic calculation of activation and the Monte Carlo approach as it is implemented in the FLUKA code. Techniques used to obtain, on the one hand, estimates of radioactivity in Becquerel and, on the other hand, residual dose rates caused by the activated material are discussed. The last part of the paper focuses on experiments that allow for benchmarking FLUKA activation calculations and on simulations used to predict activation in and around high-energy proton machines. In that respect, the paper addresses the residual dose rate that will be induced by proton-proton collisions at an energy of two times 7 TeV in and around the Compact Muon Solenoid (CMS) detector. Besides activation of solid materials, the air activation expected in the CMS cavern caused by this beam operation is also discussed. PMID:21697180

Vincke, Helmut; Theis, Chris; Roesler, Stefan

2011-07-01

288

GPU accelerated particle visualization with Splotch  

NASA Astrophysics Data System (ADS)

Splotch is a rendering algorithm for exploration and visual discovery in particle-based datasets coming from astronomical observations or numerical simulations. The strengths of the approach are production of high quality imagery and support for very large-scale datasets through an effective mix of the OpenMP and MPI parallel programming paradigms. This article reports our experiences in re-designing Splotch for exploiting emerging HPC architectures nowadays increasingly populated with GPUs. A performance model is introduced to guide our re-factoring of Splotch. A number of parallelization issues are discussed, in particular relating to race conditions and workload balancing, towards achieving optimal performances. Our implementation was accomplished by using the CUDA programming paradigm. Our strategy is founded on novel schemes achieving optimized data organization and classification of particles. We deploy a reference cosmological simulation to present performance results on acceleration gains and scalability. We finally outline our vision for future work developments including possibilities for further optimizations and exploitation of hybrid systems and emerging accelerators.

Rivi, M.; Gheller, C.; Dykes, T.; Krokos, M.; Dolag, K.

2014-07-01

289

Scheme for proton-driven plasma-wakefield acceleration of positively charged particles in a hollow plasma channel  

NASA Astrophysics Data System (ADS)

A new scheme for accelerating positively charged particles in a plasma-wakefield accelerator is proposed. If the proton drive beam propagates in a hollow plasma channel, and the beam radius is of order of the channel width, the space charge force of the driver causes charge separation at the channel wall, which helps to focus the positively charged witness bunch propagating along the beam axis. In the channel, the acceleration buckets for positively charged particles are much larger than in the blowout regime of the uniform plasma, and stable acceleration over long distances is possible. In addition, phasing of the witness with respect to the wave can be tuned by changing the radius of the channel to ensure the acceleration is optimal. Two-dimensional simulations suggest that, for proton drivers likely available in future, positively charged particles can be stably accelerated over 1 km with the average acceleration gradient of 1.3GeV/m.

Yi, Longqing; Shen, Baifei; Lotov, Konstantin; Ji, Liangliang; Zhang, Xiaomei; Wang, Wenpeng; Zhao, Xueyan; Yu, Yahong; Xu, Jiancai; Wang, Xiaofeng; Shi, Yin; Zhang, Lingang; Xu, Tongjun; Xu, Zhizhan

2013-07-01

290

Optical Diagnostics for Plasma-based Particle Accelerators  

Microsoft Academic Search

One of the challenges for plasma-based particle accelerators is to measure the spatio-temporal characteristics of the accelerated particle bunch. ``Optical'' diagnostics are particularly interesting and useful because of the large number of techniques that exits to determine the properties of photon pulses. The accelerated bunch can produce photons pulses that carry information about its characteristics for example through synchrotron radiation

Patric Muggli

2009-01-01

291

Particle beam and crabbing and deflecting structure  

DOEpatents

A new type of structure for the deflection and crabbing of particle bunches in particle accelerators comprising a number of parallel transverse electromagnetic (TEM)-resonant) lines operating in opposite phase from each other. Such a structure is significantly more compact than conventional crabbing cavities operating the transverse magnetic TM mode, thus allowing low frequency designs.

Delayen, Jean (Yorktown, VA)

2011-02-08

292

Neutral particle beams in strategic defense  

Microsoft Academic Search

This report summarizes the main elements of the current Strategic Defense Initiative program, its major risks, and the role neutral particle beams could play in reducing these risks. 13 refs., 4 tabs.

G. H. Canavan; J. C. Browne

1989-01-01

293

Neutral particle beam sensing and steering  

SciTech Connect

The direction of a neutral particle beam (NPB) is determined by detecting Ly{alpha} radiation emitted during motional quenching of excited H(25) atoms in the beam during movement of the atoms through a magnetic field. At least one detector is placed adjacent the beam exit to define an optical axis that intercepts the beam at a viewing angle to include a volume generating a selected number of photons for detection. The detection system includes a lens having an area that is small relative to the NPB area and a pixel array located in the focal plane of the lens. The lens viewing angle and area pixel array are selected to optimize the beam tilt sensitivity. In one embodiment, two detectors are placed coplanar with the beam axis to generate a difference signal that is insensitive to beam variations other than beam tilt.

Maier, W.B. II; Cobb, D.D.; Robiscoe, R.T.

1990-08-30

294

Neutral particle beam discrimination and lethality  

SciTech Connect

Using, or possibly just developing, neutral particle beams (NPBs) to both discriminate decoys and kill weapons could induce 10-fold reductions in each. The conventional factor of two'' increase in the time required to do both does not capture particle beams' impact. They could reduce the threat to {approx}1 reentry vehicle (RV) plus {approx}10 decoys per heavy missile, which could be defeated at a 10-100:1 cost effectiveness ratio by current interceptors. 8 refs., 2 figs.

Canavan, G.H.; Browne, J.C.

1991-03-01

295

Neutral Particle Beam Test Stand (NPBTS): Overview and capabilities  

SciTech Connect

The Neutral Particle Beam Test Stand provides a versatile user facility for scientific and engineering studies on large-diameter, low-divergence neutral and charged particle beams. It consists of a linac that accelerates H/sup minus/ atoms to 50 MeV at 10--12 mA and two experimental areas. Typical pulse widths are 30--150 ..mu..s at repetition rates of 0.5--30 Hz. A small rms-emittance is achieved by using a series of collimators to shave the 1.6 ..pi..-mm-mr emittance measured at the output of the linac. Typical current in the experimental areas is 500--600 ..mu..A. Experimental area A has been used to study the physics of beam diagnostics and foil neutralization and to measure (p,n) reaction cross sections. Experimental area B has a series of quadrupole objectives built by Los Alamos National Laboratory to reduce beam divergence. Typical beam characteristics are rms diameters of 10--20 cm and a full-angle divergence (rms) of 12--24 ..mu..r. The facility contains a wide variety of diagnostics including segmented Faraday cups, beam toroids, stripline beam-position monitors, and wire scanners. In addition, several new diagnostic systems for large-diameter beams have been developed by Argonne and Los Alamos. 12 refs., 8 figs.

Fink, C.L.; Novick, A.H.; Bellinger, F.O.; Brumwell, F.R.; Roche, C.T.; Rosing, M.; Yule, T.J.; Hummer, C.R.

1989-01-01

296

Strategies for mitigating the ionization-induced beam head erosion problem in an electron-beam-driven plasma wakefield accelerator  

NASA Astrophysics Data System (ADS)

Strategies for mitigating ionization-induced beam head erosion in an electron-beam-driven plasma wakefield accelerator (PWFA) are explored when the plasma and the wake are both formed by the transverse electric field of the beam itself. Beam head erosion can occur in a preformed plasma because of a lack of focusing force from the wake at the rising edge (head) of the beam due to the finite inertia of the electrons. When the plasma is produced by field ionization from the space charge field of the beam, the head erosion is significantly exacerbated due to the gradual recession (in the beam frame) of the 100% ionization contour. Beam particles in front of the ionization front cannot be focused (guided) causing them to expand as in vacuum. When they expand, the location of the ionization front recedes such that even more beam particles are completely unguided. Eventually this process terminates the wake formation prematurely, i.e., well before the beam is depleted of its energy. Ionization-induced head erosion can be mitigated by controlling the beam parameters (emittance, charge, and energy) and/or the plasma conditions. In this paper we explore how the latter can be optimized so as to extend the beam propagation distance and thereby increase the energy gain. In particular we show that, by using a combination of the alkali atoms of the lowest practical ionization potential (Cs) for plasma formation and a precursor laser pulse to generate a narrow plasma filament in front of the beam, the head erosion rate can be dramatically reduced. Simulation results show that in the upcoming “two-bunch PWFA experiments” on the FACET facility at SLAC national accelerator laboratory the energy gain of the trailing beam can be up to 10 times larger for the given parameters when employing these techniques. Comparison of the effect of beam head erosion in preformed and ionization produced plasmas is also presented.

An, W.; Zhou, M.; Vafaei-Najafabadi, N.; Marsh, K. A.; Clayton, C. E.; Joshi, C.; Mori, W. B.; Lu, W.; Adli, E.; Corde, S.; Litos, M.; Li, S.; Gessner, S.; Frederico, J.; Hogan, M. J.; Walz, D.; England, J.; Delahaye, J. P.; Muggli, P.

2013-10-01

297

Experiments of an intense H(sup -) ion beam acceleration.  

National Technical Information Service (NTIS)

An intense H(sup -) beam of a single beamlet is extracted from a large multicusp plasma source operated with cesium seeding. The H(sup -) beams are accelerated up to 100keV by a single-stage or a two-stage electrode system. Spatial profiles of the beams a...

A. Ando Y. Takeiri O. Kaneko Y. Oka K. Tsumori

1995-01-01

298

Neutral-particle-beam production and injection  

Microsoft Academic Search

A discussion of the interactions of neutral beams with confined plasmas was presented. The production and diagnosis of the neutral beams was discussed. In general, atoms, molecules, and ions of the isotopes of hydrogen are examined, but some heavier elements (for example, oxygen) are mentioned. The emphasis will be on single particle collisions, selected atomic processes on surfaces is included.

D. Post; R. Pyle

1982-01-01

299

Neutral particle beam sensing and steering.  

National Technical Information Service (NTIS)

The direction of a neutral particle beam (NPB) is determined by detecting Ly(alpha) radiation emitted during motional quenching of excited H(25) atoms in the beam during movement of the atoms through a magnetic field. At least one detector is placed adjac...

W. B. Maier D. D. Cobb R. T. Robiscoe

1990-01-01

300

Polymer surface treatment with particle beams  

DOEpatents

A polymer surface and near surface treatment process produced by irradiation with high energy particle beams is disclosed. The process is preferably implemented with pulsed ion beams. The process alters the chemical and mechanical properties of the polymer surface in a manner useful for a wide range of commercial applications. 16 figs.

Stinnett, R.W.; VanDevender, J.P.

1999-05-04

301

The production of accelerated radioactive ion beams  

SciTech Connect

During the last few years, substantial work has been done and interest developed in the scientific opportunities available with accelerated radioactive ion beams (RIBs) for nuclear physics, astrophysics, and applied research. This interest has led to the construction, development, and proposed development of both first- and second-generation RIB facilities in Asia, North America, and Europe; international conferences on RIBs at Berkeley and Louvain-la-Neuve; and many workshops on specific aspects of RIB production and science. This paper provides a discussion of both the projectile fragmentation, PF, and isotope separator on-line, ISOL, approach to RIB production with particular emphasis on the latter approach, which employs a postaccelerator and is most suitable for nuclear structure physics. The existing, under construction, and proposed facilities worldwide are discussed. The paper draws heavily from the CERN ISOLDE work, the North American IsoSpin Laboratory (ISL) study, and the operating first-generation RIB facility at Louvain-la-Neuve, and the first-generation RIB project currently being constructed at ORNL.

Olsen, D.K.

1993-11-01

302

Particle Accelerator Applications: Ion and Electron Irradiation in Materials Science, Biology and Medicine  

NASA Astrophysics Data System (ADS)

Although the developments of particle accelerators are devoted to basic study of matter constituents, since the beginning these machines have been applied with different purposes in many areas also. Today particle accelerators are essential instruments for science and technology. This work presents an overview of the main application for direct particle irradiation with accelerator in material science, biology and medicine. They are used for material synthesis by ion implantation and charged particle irradiation; to make coatings and micromachining; to characterize broad kind of samples by ion beam analysis techniques; as mass spectrometers for atomic isotopes determination. In biomedicine the accelerators are applied for the study of effects by charged particles on cells. In medicine the radiotherapy by electron irradiation is widely used, while hadrontherapy is still under development. Also, they are necessary for short life radioisotopes production required in radiodiagnostic.

Rodríguez-Fernández, Luis

2010-09-01

303

The Particle Beam Optics Interactive Computer Laboratory  

NASA Astrophysics Data System (ADS)

The Particle Beam Optics Interactive Computer Laboratory (PBO Lab) is an educational software concept to aid students and professionals in learning about charged particle beams and particle beam optical systems. The PBO Lab is being developed as a cross-platform application and includes four key elements. The first is a graphic user interface shell that provides for a highly interactive learning session. The second is a knowledge database containing information on electric and magnetic optics transport elements. The knowledge database provides interactive tutorials on the fundamental physics of charged particle optics and on the technology used in particle optics hardware. The third element is a graphical construction kit that provides tools for students to interactively and visually construct optical beamlines. The final element is a set of charged particle optics computational engines that compute trajectories, transport beam envelopes, fit parameters to optical constraints and carry out similar calculations for the student designed beamlines. The primary computational engine is provided by the third-order TRANSPORT code. Augmenting TRANSPORT is the multiple ray tracing program TURTLE and a first-order matrix program that includes a space charge model and support for calculating single particle trajectories in the presence of the beam space charge. This paper describes progress on the development of the PBO Lab.

Gillespie, George H.; Hill, Barrey W.; Brown, Nathan A.; Babcock, R. Chris; Martono, Hendy; Carey, David C.

1997-02-01

304

The Particle Beam Optics Interactive Computer Laboratory  

SciTech Connect

The Particle Beam Optics Interactive Computer Laboratory (PBO Lab) is an educational software concept to aid students and professionals in learning about charged particle beams and particle beam optical systems. The PBO Lab is being developed as a cross-platform application and includes four key elements. The first is a graphic user interface shell that provides for a highly interactive learning session. The second is a knowledge database containing information on electric and magnetic optics transport elements. The knowledge database provides interactive tutorials on the fundamental physics of charged particle optics and on the technology used in particle optics hardware. The third element is a graphical construction kit that provides tools for students to interactively and visually construct optical beamlines. The final element is a set of charged particle optics computational engines that compute trajectories, transport beam envelopes, fit parameters to optical constraints and carry out similar calculations for the student designed beamlines. The primary computational engine is provided by the third-order TRANSPORT code. Augmenting TRANSPORT is the multiple ray tracing program TURTLE and a first-order matrix program that includes a space charge model and support for calculating single particle trajectories in the presence of the beam space charge. This paper describes progress on the development of the PBO Lab. {copyright} {ital 1997 American Institute of Physics.}

Gillespie, G.H.; Hill, B.W.; Brown, N.A.; Babcock, R.C.; Martono, H. [G. H. Gillespie Associates, Inc., P.O. Box 2961, Del Mar, California 92014 (United States of America); Carey, D.C. [G. H. Gillespie Associates, Inc., P.O. Box 2961, Del Mar, California 92014 (United States of America)]|[Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, Illinois 60510 (United States)

1997-02-01

305

Diagnostic resonant cavity for a charged particle accelerator  

DOEpatents

Disclosed is a diagnostic resonant cavity for determining characteristics of a charged particle beam, such as an electron beam, produced in a charged particle accelerator. The cavity is based on resonant quadrupole-mode and higher order cavities. Enhanced shunt impedance in such cavities is obtained by the incorporation of a set of four or more electrically conductive rods extending inwardly from either one or both of the end walls of the cavity, so as to form capacitive gaps near the outer radius of the beam tube. For typical diagnostic cavity applications, a five-fold increase in shunt impedance can be obtained. In alternative embodiments the cavity may include either four or more opposing pairs of rods which extend coaxially toward one another from the opposite end walls of the cavity and are spaced from one another to form capacitative gaps; or the cavity may include a single set of individual rods that extend from one end wall to a point adjacent the opposing end wall.

Barov, Nikolai (San Diego, CA)

2007-10-02

306

Characteristics of an electron-beam rocket pellet accelerator  

SciTech Connect

A proof-of-principle (POP) electron-beam pellet accelerator has been developed and used for accelerating hydrogen and deuterium pellets. An intact hydrogen pellet was accelerated to a speed of 460 m/s by an electron beam of 13.5 keV. 0.3 A, and 2 ms. The maximum speed is limited by the acceleration path length (0.4 m) and pellet integrity. Experimental data have been collected for several hundred hydrogen pellets, which were accelerated by electron beams with parameters of voltage up to 16 kV, current up to 0.4 A, and pulse length up to 10 ms. Preliminary results reveal that the measured burn velocity increases roughly with the square of the beam voltage, as the theoretical model predicts. The final pellet velocity is proportional to the exhaust velocity, which increases with the beam power. To reach the high exhaust velocity needed for accelerating pellets to >1000 m/s, a new electron gun, with its cathode indirectly heated by a graphite heater and an electron beam, is being developed to increase beam current and power. A rocket casing or shell around the pellet has been designed and developed to increase pellet strength and improve the electron-rocket coupling efficiency. We present the characteristics of this pellet accelerator, including new improvements. 13 refs., 6 figs.

Tsai, C.C.; Foster, C.A.; Milora, S.L.; Schechter, D.E.

1991-01-01

307

High quality electron beams from a plasma channel guided laser wakefield accelerator  

SciTech Connect

Laser driven accelerators, in which particles are accelerated by the electric field of a plasma wave driven by an intense laser, have demonstrated accelerating electric fields of hundreds of GV/m. These fields are thousands of times those achievable in conventional radiofrequency (RF) accelerators, spurring interest in laser accelerators as compact next generation sources of energetic electrons and radiation. To date however, acceleration distances have been severely limited by lack of a controllable method for extending the propagation distance of the focused laser pulse. The ensuing short acceleration distance results in low energy beams with 100% electron energy spread, limiting applications. Here we demonstrate that a relativistically intense laser can be guided by a preformed plasma density channel and that the longer propagation distance can result in electron beams of percent energy spread with low emittance and increased energy, containing >10{sup 9} electrons above 80 MeV. The preformed plasma channel technique forms the basis of a new class of accelerators, combining beam quality comparable to RF accelerators with the high gradients of laser accelerators to produce compact tunable high brightness electron and radiation sources.

Geddes, C.G.R.; Toth, Cs.; van Tilborg, J.; Esarey, E.; Schroeder, C.B.; Bruhwiler, D.; Nieter, C.; Cary, J.; Leemans, W.P.

2004-07-08

308

Material shields against neutral atomic particle beams  

Microsoft Academic Search

A material shield designed to protect a spacecraft against an atomic particle beam will, of necessity, be quite massive; consequently, even modest fractional-weight savings would be significant. With this goal in mind, the particle stopping power and range in various materials were investigated. The lightest shield materials are compounds composed of hydrogen and other light elements.

S. W. Kash

1985-01-01

309

Neutral particle beam discrimination and lethality.  

National Technical Information Service (NTIS)

Using, or possibly just developing, neutral particle beams (NPBs) to both discriminate decoys and kill weapons could induce 10-fold reductions in each. The conventional ''factor of two'' increase in the time required to do both does not capture particle b...

G. H. Canavan J. C. Browne

1991-01-01

310

Plasma heating by neutral particle beams  

Microsoft Academic Search

From spring meeting of the Deutsche Physikalische Gesellschaft: pulse ; physics, plasma physics, and gas discharges, quantum optics; Berlin, Germany (9 ; Apr 1973). The heating of a plasma by means of neutral particle beams seems ; feasible, fairly simple, and very effective. The development of the necessary ; particle sources for the present-generation experiments can be taken as concluded.

Junker

1973-01-01

311

Neutral particle beam sensing and steering  

SciTech Connect

The direction of a neutral particle beam (NPB) is determined by detecting Lya radiation emitted during motional quenching of excited H(2S) atoms in the beam during movement of the atoms through a magnetic exit to define an optical axis that intercepts the beam at a viewing angle to include a volume generating a selected number of photons for detection. The detection system includes a lens having an area that is small relative to the NPB area and a pixel array located in the focal plane of the lens. The lens viewing angle and area pixel array are selected to optimize the beam tilt sensitivity. In one embodiment two detectors are placed coplanar with the beam axis to generate a difference signal that is insensitive to beam variations, other than beam tilt.

Maier, W.B.; Cobb, D.D.; Robiscoe, R.T.

1991-08-27

312

Radioactive beams with the HHIRF accelerators  

SciTech Connect

There is an increasing interest in radioactive ion beams for astrophysics and nuclear physics research and applied programs. This interest has led to an International Conference on Radioactive Nuclear Beams and a Workshop on the Science of Intense Radioactive Ion Beams. In addition, a steering committee has been formed to consider the development of a very large and intense RIB facility in North America to produce both proton- and neutron-rich beams. This report discusses development of these beams.

Olsen, D.K.; Alton, G.D.; Baktash, C.; Dowling, D.T.; Garrett, J.D.; Haynes, D.L.; Jones, C.M.; Juras, R.C., Lane, S.N.; Lee, I.Y.; Meigs, M.J.; Mills, G.D.; Mosko, S.W.; Tatum, B.A. Toth, K.S. (Oak Ridge National Lab., TN (USA)); Carter, H.K. (UNISOR, Oak Ridge, TN (USA))

1991-01-01

313

A Magnetorestrictive Tuning System for Particle Accelerators  

SciTech Connect

Energen, Inc. has designed, built, and demonstrated several fast and slow tuners based on its magnetostrictive actuators and stepper motor. These tuners are designed for Superconducting Radio Frequency (SRF) cavities, which are important structures in particle accelerators that support a wide spectrum of disciplines, including nuclear and high-energy physics and free electron lasers (FEL). In the past two years, Energen's work has focused on magnetostrictive fast tuners for microphonics and Lorentz detuning compensation on elliptical-cell and spoke-loaded cavities. These tuners were custom designed to meet specific requirements, which included a few to 100 micron stroke range, hundreds to kilohertz operation frequency, and cryogenic temperature operation in vacuum or liquid helium. These tuners have been tested in house and at different laboratories, such as DESY, Argonne National Lab, and Jefferson Lab. Some recent results are presented in this paper.

Chiu-Ying Tai; Jordan Cormier; William Espinola; Zhixiu Han; Chad Joshi; Anil Mavanur; Livia Racz; Kenneth Shepard; Edward Daly; Kirk Davis

2005-05-16

314

A Novel Method for Rigorously Analyzing Beam Loading Effect Based on the Macro-Particle Model  

NASA Astrophysics Data System (ADS)

The beam loading effect is a considerable issue for a high average current beam. We apply a novel method without utilizing the specious beam current value to rigorously analyze the beam loading effect in S-band linacs. By tracking every macro-particle's state and using the energy conservation law, power dissipated from the beam is calculated in each cell. In the new particle-based algorithm, the concept of equivalent beam current is proposed. Its value is not constant and it has a small variation through the accelerating structure. Also, we introduce the iteration algorithm as comparison and we find that the two algorithms coincide with each other very well.

Chen, Qu-Shan; Pei, Yuan-Ji; Hu, Tong-Ning; Qin, Bin

2014-01-01

315

Observation of Beam Loading in a Laser-Plasma Accelerator  

SciTech Connect

Beam loading is the phenomenon which limits the charge and the beam quality in plasma based accelerators. An experimental study conducted with a laser-plasma accelerator is presented. Beam loading manifests itself through the decrease of the beam energy, the reduction of dark current, and the increase of the energy spread for large beam charge. 3D PIC simulations are compared to the experimental results and confirm the effects of beam loading. It is found that, in our experimental conditions, the trapped electron beams generate decelerating fields on the order of 1 (GV/m)/pC and that beam loading effects are optimized for trapped charges of about 20 pC.

Rechatin, C.; Ismail, A. Ben; Lim, J.; Faure, J.; Malka, V. [Laboratoire d'Optique Appliquee, ENSTA, CNRS, Ecole Polytechnique, UMR 7639, 91761 Palaiseau (France); Davoine, X.; Lefebvre, E. [CEA, DAM, DIF, Bruyeres-le-Chatel, 91297 Arpajon (France); Lifschitz, A. [Laboratoire d'Optique Appliquee, ENSTA, CNRS, Ecole Polytechnique, UMR 7639, 91761 Palaiseau (France); Laboratoire de Physique des Gaz et des Plasmas, CNRS, UMR 8578, Universite Paris XI, Batiment 210, 91405 Orsay cedex (France)

2009-11-06

316

US Particle Accelerators at Age 50.  

ERIC Educational Resources Information Center

Reviews the development of accelerators over the past 50 years. Topics include: types of accelerators, including cyclotrons; sociology of accelerators (motivation, financing, construction, and use); impact of war; national laboratories; funding; applications; future projects; foreign projects; and international collaborations. (JN)

Wilson, R. R.

1981-01-01

317

Self-accelerating self-trapped optical beams.  

PubMed

We present self-accelerating self-trapped beams in nonlinear optical media, exhibiting self-focusing and self-defocusing Kerr and saturable nonlinearities, as well as a quadratic response. In Kerr and saturable media such beams are stable under self-defocusing and weak self-focusing, whereas for strong self-focusing the beams off-shoot solitons while their main lobe continues to accelerate. Self-accelerating self-trapped wave packets are universal, and can also be found in matter waves, plasma, etc. PMID:21699299

Kaminer, Ido; Segev, Mordechai; Christodoulides, Demetrios N

2011-05-27

318

Optical Phase Locking of Modelocked Lasers for Particle Accelerators  

SciTech Connect

Particle accelerators require precise phase control of the electric field through the entire accelerator structure. Thus a future laser driven particle accelerator will require optical synchronism between the high-peak power laser sources that power the accelerator. The precise laser architecture for a laser driven particle accelerator is not determined yet, however it is clear that the ability to phase-lock independent modelocked oscillators will be of crucial importance. We report the present status on our work to demonstrate long term phaselocking between two modelocked lasers to within one degree of optical phase and describe the optical synchronization techniques that we employ.

Plettner, T.; Sinha, S.; Wisdom, J.; /Stanford U., Phys. Dept.; Colby, E.R.; /SLAC

2006-02-17

319

Particle Acceleration in Relativistic Jets Due to Weibel Instability  

Microsoft Academic Search

Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. Using a three-dimensional relativistic electromagnetic particle code, we have investigated particle acceleration associated with a relativistic jet front propagating through an ambient

K.-I. Nishikawa; P. Hardee; G. Richardson; R. Preece; H. Sol; G. J. Fishman

2003-01-01

320

Self-accelerating Airy Beams: Generation, Control, and Applications  

NASA Astrophysics Data System (ADS)

Recently, a specific type of nondiffracting beams named self-accelerating Airy beams has attracted a great deal of interest due to their unique properties and many proposed applications in areas such as optical micromanipulation, plasma guidance, vacuum electron acceleration, and routing surface plasmon polaritons. In contradistinction with Bessel beams, Airy beams do not rely on simple conical superposition of plane waves, and they possess the properties of self-acceleration in addition to nondiffraction and self-healing. For the past few years, tremendous research work has been devoted to the study of Airy beams, from theoretical predictions to experimental observations, from linear control to nonlinear self-trapping, and from fundamental aspects to demonstrations of potential applications. In this chapter, we provide an overview on generation and control of Airy beams and recent developments in the area.

Hu, Yi; Siviloglou, Georgios A.; Zhang, Peng; Efremidis, Nikolaos K.; Christodoulides, Demetrios N.; Chen, Zhigang

321

Merging for Particle-Mesh Complex Particle Kinetic Modeling of the Multiple Plasma Beams  

NASA Technical Reports Server (NTRS)

We suggest a merging procedure for the Particle-Mesh Complex Particle Kinetic (PMCPK) method in case of inter-penetrating flow (multiple plasma beams). We examine the standard particle-in-cell (PIC) and the PMCPK methods in the case of particle acceleration by shock surfing for a wide range of the control numerical parameters. The plasma dynamics is described by a hybrid (particle-ion-fluid-electron) model. Note that one may need a mesh if modeling with the computation of an electromagnetic field. Our calculations use specified, time-independent electromagnetic fields for the shock, rather than self-consistently generated fields. While a particle-mesh method is a well-verified approach, the CPK method seems to be a good approach for multiscale modeling that includes multiple regions with various particle/fluid plasma behavior. However, the CPK method is still in need of a verification for studying the basic plasma phenomena: particle heating and acceleration by collisionless shocks, magnetic field reconnection, beam dynamics, etc.

Lipatov, Alexander S.

2011-01-01

322

Tumour therapy with particle beams  

Microsoft Academic Search

Photons are exponentially attenuated in matter producing high doses close to the surface. Therefore they are not well suited for the treatment of deep seated tumours. Charged particles, in contrast, exhibit a sharp increase of ionization density close to the end of their range, the so-called Bragg-peak. The depth of the Bragg-peak can be adjusted by varying the particle's energy.

Claus Grupen

2000-01-01

323

Current Fragmentation and Particle Acceleration in Solar Flares  

NASA Astrophysics Data System (ADS)

Particle acceleration in solar flares remains an outstanding problem in plasma physics and space science. While the observed particle energies and timescales can perhaps be understood in terms of acceleration at a simple current sheet or turbulence site, the vast number of accelerated particles, and the fraction of flare energy in them, defies any simple explanation. The nature of energy storage and dissipation in the global coronal magnetic field is essential for understanding flare acceleration. Scenarios where the coronal field is stressed by complex photospheric motions lead to the formation of multiple current sheets, rather than the single monolithic current sheet proposed by some. The currents sheets in turn can fragment into multiple, smaller dissipation sites. MHD, kinetic and cellular automata models are used to demonstrate this feature. Particle acceleration in this environment thus involves interaction with many distributed accelerators. A series of examples demonstrate how acceleration works in such an environment. As required, acceleration is fast, and relativistic energies are readily attained. It is also shown that accelerated particles do indeed interact with multiple acceleration sites. Test particle models also demonstrate that a large number of particles can be accelerated, with a significant fraction of the flare energy associated with them. However, in the absence of feedback, and with limited numerical resolution, these results need to be viewed with caution. Particle in cell models can incorporate feedback and in one scenario suggest that acceleration can be limited by the energetic particles reaching the condition for firehose marginal stability. Contemporary issues such as footpoint particle acceleration are also discussed. It is also noted that the idea of a "standard flare model" is ill-conceived when the entire distribution of flare energies is considered.

Cargill, P. J.; Vlahos, L.; Baumann, G.; Drake, J. F.; Nordlund, Å.

2012-11-01

324

Application of the Reduction of Scale Range in a Lorentz Boosted Frame to the Numerical Simulation of Particle Acceleration Devices.  

National Technical Information Service (NTIS)

It has been shown that it may be computationally advantageous to perform computer simulations in a boosted frame for a certain class of systems: particle beams interacting with electron clouds, free electron lasers, and laserplasma accelerators. However, ...

C. G. Geddes D. P. Grote F. Cormier-Michel J. Vay W. M. Fawle

2009-01-01

325

The use of particle accelerators for space projects  

NASA Astrophysics Data System (ADS)

With the introduction of CMOS technology radiation effects in components became an important issue in satellite and space mission projects. At the end of the cold war, the market of radiation hard (RadHard) components crashed and during the 90's their fabrication practically stopped. The use of ''commercial-off-the-shelf'' (COTS) components became more common but required increased evaluation activities at radiation test sites. Component manufacturers and space project engineers were directed towards these test sites, in particular, towards particle accelerators. Many accelerator laboratories developed special beam lines and constructed dedicated test areas for component evaluations. The space environment was simulated at these test sites and components were tested to levels often exceeding mission requirements. In general, space projects environments were predicted in respects to particle mass and energy distributions with the expected fluxes and fluences. In order to validate this information in tests, concepts like stopping power, linear energy transfer, ion penetration ranges etc. have to be understood. The knowledge from the component structure also defines the way of irradiation. For example, the higher ion energies resulting in much deeper ion penetration ranges allow successful reverse side irradiation of thinned Integrated Circuits (ICs). So overall increased demands for radiation testing attracted the European Space Agency (ESA) to the JYFL-accelerator laboratory of the University of Jyväskylä, Finland. A contract was signed between ESA and JYFL for the development of a ''High Penetrating Heavy Ion Test Site'' [1]. Following one year development, this test site was commissioned in May 2005. This paper addresses the various issues around the JYFL laboratory with its accelerator and radiation effects facility as the focal point in service of component evaluations for the space community.

Virtanen, Ari

2006-05-01

326

Stability of diaphragmed electron beams in a linear induction accelerator  

NASA Astrophysics Data System (ADS)

The effects of electromagnetic shielding of an electron beam by a series of metal diaphragms on transverse stability of beam motion are considered. The shielding coefficients are calculated for the quasistationary electric and magnetic fields of a beam displaced from the axis of the accelerator. The axial magnetic field strengths required for coherent beam focusing are calculated, and the growth rate of an unstable unsymmetric hybrid wave in the electron beam is found for a beam in a slow-wave structure formed by a series of diaphragms. It is shown that the destabilizing influence of the diaphragms can be reduced by increasing the period-to-radius ratio of the structure.

Aleksakhin, Iu. I.; Perelshtein, E. A.

1983-11-01

327

Intense microwave and particle beams III; Proceedings of the Meeting, Los Angeles, CA, Jan. 20-24, 1992  

NASA Astrophysics Data System (ADS)

Various papers on intense microwave and particle beams are presented. The general topics addressed include: high-power microwave sources, directed energy concepts, and advanced accelerators and intense particle beams. Individual topics addressed include: experiments using laser-triggered electrical discharges to generate electromagnetic missiles, beam waveguide design for high-power applications, quasi-optical solid state microwave sources.

Brandt, Howard E.

328

Particle-in-cell simulations of intense charged particle beam transport  

NASA Astrophysics Data System (ADS)

In this dissertation, several different problems in charged particle beam transport are examined using large- scale, particle-in-cell (PIC) numerical simulations. Problems considered here are relevant to a number of different applications including high-power microwave generation, collective ion acceleration, plasma heating, and ion-beam-driven inertial-confinement-fusion (ICF). The PIC simulation method is reviewed and the constraints associated with the simulation of intense charged particle beams are given. In Part I, space-charge limiting currents for intense relativistic electron beams propagating along applied magnetic fields are simulated and compared with one-dimensional analytic theory. Good agreement between simulations and recent analytic theory is found. For injected beam currents exceeding the limiting value, a two-dimensional, electrostatic, analytic estimate of the transmitted current is found to be in poor agreement with two-dimensional PIC simulations. In Part II, two-dimensional PIC simulations are used to determine the propagation distance of electron-positron beams in dense background plasmas. The simulation results are in good agreement with a zero- dimensional stability model. This model has been used previously to estimate beam propagation distances in the early stages of astrophysical beam transport. In Part III, the transport of intense relativistic high- ?b electron beams injected across applied magnetic fields is simulated using two and three- dimensional PIC codes in an effort to compare with a recent theoretical analysis. However, the combined physical and numerical constraints are shown to prevent adequate simulation fidelity for a detailed comparison. In Part IV, the transport of intense ion beams, primarily applicable to ion-beam-driven ICF, is studied. The goal is to examine possible deleterious beam-beam interactions in multiple beam configurations envisioned for light-ion ICF reactor scenarios. Numerical simulations are used in combination with analytic methods to explore nearest neighbor beam-beam interactions and multiple-beam overlap conditions. Results obtained here indicate that nearest neighbor beam-beam interactions do not result in significant reduction of delivered ion beam power to the target. Where possible, the results of different PIC codes are compared and contrasted throughout this work.

Rose, David Vincent

1997-11-01

329

Advanced treatment planning methods for efficient radiation therapy with laser accelerated proton and ion beams  

SciTech Connect

Purpose: Laser plasma acceleration can potentially replace large and expensive cyclotrons or synchrotrons for radiotherapy with protons and ions. On the way toward a clinical implementation, various challenges such as the maximum obtainable energy still remain to be solved. In any case, laser accelerated particles exhibit differences compared to particles from conventional accelerators. They typically have a wide energy spread and the beam is extremely pulsed (i.e., quantized) due to the pulsed nature of the employed lasers. The energy spread leads to depth dose curves that do not show a pristine Bragg peak but a wide high dose area, making precise radiotherapy impossible without an additional energy selection system. Problems with the beam quantization include the limited repetition rate and the number of accelerated particles per laser shot. This number might be too low, which requires a high repetition rate, or it might be too high, which requires an additional fluence selection system to reduce the number of particles. Trying to use laser accelerated particles in a conventional way such as spot scanning leads to long treatment times and a high amount of secondary radiation produced when blocking unwanted particles. Methods: The authors present methods of beam delivery and treatment planning that are specifically adapted to laser accelerated particles. In general, it is not necessary to fully utilize the energy selection system to create monoenergetic beams for the whole treatment plan. Instead, within wide parts of the target volume, beams with broader energy spectra can be used to simultaneously cover multiple axially adjacent spots of a conventional dose delivery grid as applied in intensity modulated particle therapy. If one laser shot produces too many particles, they can be distributed over a wider area with the help of a scattering foil and a multileaf collimator to cover multiple lateral spot positions at the same time. These methods are called axial and lateral clustering and reduce the number of particles that have to be blocked in the beam delivery system. Furthermore, the optimization routine can be adjusted to reduce the number of dose spots and laser shots. The authors implemented these methods into a research treatment planning system for laser accelerated particles. Results: The authors' proposed methods can decrease the amount of secondary radiation produced when blocking particles with wrong energies or when reducing the total number of particles from one laser shot. Additionally, caused by the efficient use of the beam, the treatment time is reduced considerably. Both improvements can be achieved without extensively changing the quality of the treatment plan since conventional intensity modulated particle therapy usually includes a certain amount of unused degrees of freedom which can be used to adapt to laser specific properties. Conclusions: The advanced beam delivery and treatment planning methods reduce the need to have a perfect laser-based accelerator reproducing the properties of conventional accelerators that might not be possible without increasing treatment time and secondary radiation to the patient. The authors show how some of the differences to conventional beams can be overcome and efficiently used for radiation treatment.

Schell, Stefan; Wilkens, Jan J. [Department of Radiation Oncology, Technische Universitaet Muenchen, Klinikum Rechts der Isar, Ismaninger Str. 22, 81675 Muenchen (Germany)

2010-10-15

330

Multiple beam induction accelerators for heavy ion fusion  

NASA Astrophysics Data System (ADS)

Induction accelerators are appealing for heavy-ion driven inertial fusion energy (HIF) because of their high efficiency and their demonstrated capability to accelerate high beam current (?10 kA in some applications). For the HIF application, accomplishments and challenges are summarized. HIF research and development has demonstrated the production of single ion beams with the required emittance, current, and energy suitable for injection into an induction linear accelerator. Driver scale beams have been transported in quadrupole channels of the order of 10% of the number of quadrupoles of a driver. We review the design and operation of induction accelerators and the relevant aspects of their use as drivers for HIF. We describe intermediate research steps that would provide the basis for a heavy-ion research facility capable of heating matter to fusion relevant temperatures and densities, and also to test and demonstrate an accelerator architecture that scales well to a fusion power plant.

Seidl, Peter A.; Barnard, John J.; Faltens, Andris; Friedman, Alex; Waldron, William L.

2014-01-01

331

ISABELLE accelerator software, control system, and beam diagnostic philosophy  

SciTech Connect

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

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

1981-01-01

332

Beam dynamics in a long-pulse linear induction accelerator  

SciTech Connect

The second axis of the Dual Axis Radiography of Hydrodynamic Testing (DARHT) facility produces up to four radiographs within an interval of 1.6 microseconds. It accomplishes this by slicing four micro-pulses out of a long 1.8-kA, 16.5-MeV electron beam pulse and focusing them onto a bremsstrahlung converter target. The long beam pulse is created by a dispenser cathode diode and accelerated by the unique DARHT Axis-II linear induction accelerator (LIA). Beam motion in the accelerator would be a problem for radiography. High frequency motion, such as from beam breakup instability, would blur the individual spots. Low frequency motion, such as produced by pulsed power variation, would produce spot to spot differences. In this article, we describe these sources of beam motion, and the measures we have taken to minimize it.

Ekdahl, Carl [Los Alamos National Laboratory; Abeyta, Epifanio O [Los Alamos National Laboratory; Aragon, Paul [Los Alamos National Laboratory; Archuleta, Rita [Los Alamos National Laboratory; Cook, Gerald [Los Alamos National Laboratory; Dalmas, Dale [Los Alamos National Laboratory; Esquibel, Kevin [Los Alamos National Laboratory; Gallegos, Robert A [Los Alamos National Laboratory; Garnett, Robert [Los Alamos National Laboratory; Harrison, James F [Los Alamos National Laboratory; Johnson, Jeffrey B [Los Alamos National Laboratory; Jacquez, Edward B [Los Alamos National Laboratory; Mc Cuistian, Brian T [Los Alamos National Laboratory; Montoya, Nicholas A [Los Alamos National Laboratory; Nath, Subrato [Los Alamos National Laboratory; Nielsen, Kurt [Los Alamos National Laboratory; Oro, David [Los Alamos National Laboratory; Prichard, Benjamin [Los Alamos National Laboratory; Rose, Chris R [Los Alamos National Laboratory; Sanchez, Manolito [Los Alamos National Laboratory; Schauer, Martin M [Los Alamos National Laboratory; Seitz, Gerald [Los Alamos National Laboratory; Schulze, Martin [Los Alamos National Laboratory; Bender, Howard A [Los Alamos National Laboratory; Broste, William B [Los Alamos National Laboratory; Carlson, Carl A [Los Alamos National Laboratory; Frayer, Daniel K [Los Alamos National Laboratory; Johnson, Douglas E [Los Alamos National Laboratory; Tom, C Y [Los Alamos National Laboratory; Trainham, C [Los Alamos National Laboratory; Williams, John [Los Alamos National Laboratory; Scarpetti, Raymond [LLNL; Genoni, Thomas [VOSS; Hughes, Thomas [VOSS; Toma, Carsten [VOSS

2010-01-01

333

Acceleration of ampere class H(-) ion beam by MeV accelerator.  

PubMed

The H(-) ion accelerator R&D to realize the international thermonuclear experimental reactor neutral beam is ongoing at Japan Atomic Energy Agency (JAEA). The required performance for the prototype MeV accelerator developed at JAEA is 1 MeV, 500 mA (current density of 200 A/m(2)) H(-) ion beam at the beamlet divergence angle of less than 7 mrad. Up to 2005, 836 keV, 146 A/m(2) H(-) ion beam was successfully accelerated as the highest record of the current density at MeV class energy beams. In the present work, high current negative ion beam acceleration test was performed by increasing the beam extraction apertures from 3 x 3 (9 apertures) to 3 x 5 (15 apertures). By fixing the air leak at the source chamber due to backstream ions as well as the improvement of voltage holding capability by a new fiber reinforced plastic insulator ring, the performance of the MeV accelerator was improved. So far, H(-) ion beam of 320 mA was successfully accelerated up to 796 keV with the beam divergence angle of 5.5 mrad. The accelerated drain current including the electron reaches close to the power supply limit for the MeV test facility. The heat flux by the backstream ion during the above beam acceleration was estimated to be 360 W/cm(2). The Cs leakage to the accelerator during the test campaign (Cs total input of 5.0 g) was 0.26 mg (7.0 microg/cm(2)). This is considered to be the allowable level from the viewpoint of voltage holding. PMID:18315236

Taniguchi, M; Inoue, T; Umeda, N; Kashiwagi, M; Watanabe, K; Tobari, H; Dairaku, M; Sakamoto, K

2008-02-01

334

Acceleration of ampere class H- ion beam by MeV accelerator  

NASA Astrophysics Data System (ADS)

The H- ion accelerator R&D to realize the international thermonuclear experimental reactor neutral beam is ongoing at Japan Atomic Energy Agency (JAEA). The required performance for the prototype MeV accelerator developed at JAEA is 1 MeV, 500 mA (current density of 200 A/m2) H- ion beam at the beamlet divergence angle of less than 7 mrad. Up to 2005, 836 keV, 146 A/m2 H- ion beam was successfully accelerated as the highest record of the current density at MeV class energy beams. In the present work, high current negative ion beam acceleration test was performed by increasing the beam extraction apertures from 3×3 (9 apertures) to 3×5 (15 apertures). By fixing the air leak at the source chamber due to backstream ions as well as the improvement of voltage holding capability by a new fiber reinforced plastic insulator ring, the performance of the MeV accelerator was improved. So far, H- ion beam of 320 mA was successfully accelerated up to 796 keV with the beam divergence angle of 5.5 mrad. The accelerated drain current including the electron reaches close to the power supply limit for the MeV test facility. The heat flux by the backstream ion during the above beam acceleration was estimated to be 360 W/cm2. The Cs leakage to the accelerator during the test campaign (Cs total input of 5.0 g) was 0.26 mg (7.0 ?g/cm2). This is considered to be the allowable level from the viewpoint of voltage holding.

Taniguchi, M.; Inoue, T.; Umeda, N.; Kashiwagi, M.; Watanabe, K.; Tobari, H.; Dairaku, M.; Sakamoto, K.

2008-02-01

335

Particle beam generator using a radioactive source  

DOEpatents

The apparatus of the present invention selects from particles emitted by a radioactive source those particles having momentum within a desired range and focuses the selected particles in a beam having at least one narrow cross-dimension, and at the same time attenuates potentially disruptive gamma rays and low energy particles. Two major components of the present invention are an achromatic bending and focusing system, which includes sector magnets and quadrupole, and a quadrupole doublet final focus system. Permanent magnets utilized in the apparatus are constructed of a ceramic (ferrite) material which is inexpensive and easily machined.

Underwood, David G. (Naperville, IL)

1993-01-01

336

Particle beam generator using a radioactive source  

DOEpatents

The apparatus of the present invention selects from particles emitted by a radioactive source those particles having momentum within a desired range and focuses the selected particles in a beam having at least one narrow cross-dimension, and at the same time attenuates potentially disruptive gamma rays and low energy particles. Two major components of the present invention are an achromatic bending and focusing system, which includes sector magnets and quadrupole, and a quadrupole doublet final focus system. Permanent magnets utilized in the apparatus are constructed of a ceramic (ferrite) material which is inexpensive and easily machined.

Underwood, D.G.

1993-03-30

337

G4beamline Particle Tracking in Matter Dominated Beam Lines  

SciTech Connect

The G4beamline program is a useful and steadily improving tool to quickly and easily model beam lines and experimental equipment without user programming. It has both graphical and command-line user interfaces. Unlike most accelerator physics codes, it easily handles a wide range of materials and fields, being particularly well suited for the study of muon and neutrino facilities. As it is based on the Geant4 toolkit, G4beamline includes most of what is known about the interactions of particles with matter. We are continuing the development of G4beamline to facilitate its use by a larger set of beam line and accelerator developers. A major new feature is the calculation of space-charge effects. G4beamline is open source and freely available at http://g4beamline.muonsinc.com

T.J. Roberts, K.B. Beard, S. Ahmed, D. Huang, D.M. Kaplan

2011-03-01

338

Secondary particle production from laser accelerated beams  

SciTech Connect

3-MeV protons and fusion neutrons are generated by focused radiation of the 3-TW Prague Asterix Laser System (PALS). 30-mA current of 3-MeV protons is detected behind the target in the forward direction when a hydrogenated silicon foil is used. The co-occurrence of bursts in the emission of ions and fusion neutrons from CD{sub 2} plasma is observed. The energy of produced deuteron bursts is high enough to drive deuterium fusion in CD{sub 2} catcher targets.

Krasa, Josef; Margarone, Daniele [Institute of Physics ASCR, Na Slovance 2, 182 21 Prague 8 (Czech Republic)

2012-07-09

339

Beam collimation and transport of quasineutral laser-accelerated protons by a solenoid field  

NASA Astrophysics Data System (ADS)

This article reports about controlling laser-accelerated proton beams with respect to beam divergence and energy. The particles are captured by a pulsed high field solenoid with a magnetic field strength of 8.6 T directly behind a flat target foil that is irradiated by a high intensity laser pulse. Proton beams with energies around 2.3 MeV and particle numbers of 1012 could be collimated and transported over a distance of more than 300 mm. In contrast to the protons the comoving electrons are strongly deflected by the solenoid field. They propagate at a submillimeter gyroradius around the solenoid's axis which could be experimentally verified. The originated high flux electron beam produces a high space charge resulting in a stronger focusing of the proton beam than expected by tracking results. Leadoff particle-in-cell simulations show qualitatively that this effect is caused by space charge attraction due to the comoving electrons. The collimation and transport of laser-accelerated protons is the first step to provide these unique beams for further applications such as postacceleration by conventional accelerator structures.

Harres, K.; Alber, I.; Tauschwitz, A.; Bagnoud, V.; Daido, H.; Günther, M.; Nürnberg, F.; Otten, A.; Schollmeier, M.; Schütrumpf, J.; Tampo, M.; Roth, M.

2010-02-01

340

Physics of a Repetitively Pulsed 10 KAmp Electron Beam Accelerator.  

National Technical Information Service (NTIS)

Some aspects of physics that contributed to design and operation of the ETA 10 kAmp electron accelerator are discussed. These include: the electron source, the emittance growth in the injector, beam transport through the accelerator, and the influence of ...

T. J. Fessenden W. A. Atchison D. L. Birx R. J. Briggs J. C. Clark

1981-01-01

341

Beam Dynamics Issues of Muon Acceleration in RLA.  

National Technical Information Service (NTIS)

A conceptual design of a muon acceleration based on recirculating superconducting linacs is proposed. In the presented scenario, acceleration starts after ionization cooling at 210 MeV/c and proceeds to 20 GeV, where the beam is injected into a neutrino f...

S. A. Bogacz

2005-01-01

342

Two-Beam Accelerator: structure studies and 35 GHz experiments  

SciTech Connect

The Two-Beam Accelerator (TBA) shows great promise for achieving high accelerating gradients, perhaps >250 MV/m, for such machines as electron linear colliders. This paper presents the results of studies of candidate structures for a TBA. Also, the hardware and program for 35 GHz high-gradient testing are described. 18 refs., 13 figs.

Hopkins, D.B.; Kuenning, R.W.

1985-05-01

343

Cavitation Inception on Microparticles: A Self-Propelled Particle Accelerator  

Microsoft Academic Search

Corrugated, hydrophilic particles with diameters between 30 and 150 mum are found to cause cavitation inception at their surfaces when they are exposed to a short, intensive tensile stress wave. The growing cavity accelerates the particle into translatory motion until the tensile stress decreases, and subsequently the particle separates from the cavity. The cavity growth and particle detachment are modeled

Manish Arora; Claus-Dieter Ohl; Knud Aage Mørch

2004-01-01

344

Accelerators  

NSDL National Science Digital Library

What is the purpose of particle accelerators? On this web page, part of a particle physics tutorial, students read that accelerators solve two problems. The accelerators provide an increase in momentum to produce particles of small wavelength, and the fast-moving particles can create new particles when smashed together. A photograph of the inside of a particle accelerator is provided. Copyright 2005 Eisenhower National Clearinghouse

Group, Lawrence B.

2002-01-01

345

Neutral particle beam alternative concept for ITER  

Microsoft Academic Search

An analysis of an ITER neutral particle beam system is presented. The analysis covers the neutralizer, ion dumps, pumping, and geometric aspects. The US beam concept for ITER consists of three or four clusters of beamlines delivering approximately 80 MW total of 1.6-MeV deuterium to three or four reactor ports. Each cluster has three self-contained beamlines featuring plasma neutralizers and

D. Sedgley; J. Brook; T. Luzzi; L. Deutsch

1989-01-01

346

Neutral-particle-beam production and injection  

SciTech Connect

This paper is divided into two sections: the first is a discussion of the interactions of neutral beams with confined plasmas, the second is concerned with the production and diagnosis of the neutral beams. In general we are dealing with atoms, molecules, and ions of the isotopes of hydrogen, but some heavier elements (for example, oxygen) will be mentioned. The emphasis will be on single-particle collisions; selected atomic processes on surfaces will be included.

Post, D.; Pyle, R.

1982-07-01

347

Fluence and dose measurements for an accelerator neutron beam  

NASA Astrophysics Data System (ADS)

The 3 MV Van de Graaff accelerator at McMaster University accelerator laboratory is extended to a neutron irradiation facility for low-dose bystander effects research. A long counter and an Anderson-Braun type neutron monitor have been used as monitors for the determination of the total fluence. Activation foils were used to determine the thermal neutron fluence rate (around 10 6 neutrons s -1). Meanwhile, the interactions of neutrons with the monitors have been simulated using a Monte Carlo N Particle (MCNP) code. Bystander effects, i.e. damage occurring in cells that were not traversed by radiation but were in the same radiation environment, have been well observed following both alpha and gamma irradiation of many cell lines. Since neutron radiation involves mixed field (including gamma and neutron radiations), we need to differentiate the doses for the bystander effects from the two radiations. A tissue equivalent proportional counter (TEPC) filled with propane based tissue equivalent gas simulating a 2 ?m diameter tissue sphere has been investigated to estimate the neutron and gamma absorbed doses. A photon dose contamination of the neutron beam is less than 3%. The axial dose distribution follows the inverse square law and lateral and vertical dose distributions are relatively uniform over the irradiation area required by the biological study.

Liu, Z.; Byun, S. H.; McNeill, F. E.; Mothersill, C. E.; Seymour, C. B.; Prestwich, W. V.

2007-10-01

348

Education in a rapidly advancing technology: Accelerators and beams  

NASA Astrophysics Data System (ADS)

The field of accelerators and beams (A&B) is one of today's fast changing technologies. Because university faculties have not been able to keep pace with the associated advancing knowledge, universities have not been able to play their traditional role of educating the scientists and engineers needed to sustain this technology for use in science, industry, commerce, and defense. This problem for A&B is described and addressed. The solution proposed, a type of ``distance'' education, is the U.S. Particle Accelerator School (USPAS) created in the early 1980s. USPAS provides the universities with a means of serving the education needs of the institutions using A&B, primarily but not exclusively the national laboratories. The field of A&B is briefly summarized. The need for education outside the university framework, the raison d'être for USPAS, the USPAS method, program structure, and curriculum, and particular USPAS-university connections are explained. The management of USPAS is analyzed, including its unique administrative structure, its institutional ties, and its operations, finance, marketing, and governmental relations. USPAS performance over the years is documented and a business assessment is made. Finally, there is a brief discussion of the future potential for this type of educational program, including possible extrapolation to new areas and/or different environments, in particular, its extra-government potential and its international possibilities.

Month, Mel

2000-06-01

349

How important are dispersive Alfvén waves for auroral particle acceleration?  

Microsoft Academic Search

The means by which charged particles are accelerated in space to form the aurora is still not fully understood. This acceleration produces earthward streaming electrons driving auroral luminosity and outward streaming ionospheric ions which populate space with terrestrial matter. With the advent of high resolution space borne field and particle instruments, dispersive Alfvén waves (DAWs) have been identified as drivers

C. C. Chaston; C. W. Carlson; J. P. McFadden; R. E. Ergun; R. J. Strangeway

2007-01-01

350

Particle acceleration in collisionless shocks - Regulated injection and high efficiency  

Microsoft Academic Search

Particle acceleration in supernova remnants and radio galaxies proceeds with high efficiency, and at the same time puts out most of the cosmic ray power at moderately relativistic energies. This suggests that there is a regulated injection mechanism that selects only a very small fraction of particles out of the thermal pool, but enough that, when accelerated to moderately relativistic

D. Eichler

1979-01-01

351

Plasma wakefield excitation by charge particle beams  

Microsoft Academic Search

Electron plasma waves excited by a charge bunch are studied analytically and via computer simulations in full generality. Analytic results of plasma wakefield excitation are compared with particle-in-cell computer simulations both qualitatively and quantitatively. Doppler shifts and the nonlinear properties of plasma waves are included. One of the major goals is to study plasma applications to high energy physics. Accelerator

Jao-Jang Su; Jaojang

1990-01-01

352

Beam trapping in the NRL modified betatron accelerator. Interim report  

SciTech Connect

The experimental results on the trapping of the beam NRL modified betatron accelerator are in good agreement with a revised model of resistive trapping and thus it may be concluded that the wall resistivity is responsible for the inward spiral motion of the beam after injection.

Kapetanakos, C.A.; Dialetis, D.; Marsh, S.J.; Len, K.L.; Smith, T.

1991-05-15

353

Induction Accelerator Technology Choices for the Integrated Beam Experiment (IBX)  

SciTech Connect

Over the next three years the research program of the Heavy Ion Fusion Virtual National Laboratory (HIF-VNL), a collaboration among LBNL, LLNL, and PPPL, is focused on separate scientific experiments in the injection, transport and focusing of intense heavy ion beams at currents from 100 mA to 1 A. As a next major step in the HIF-VNL program, we aim for a complete 'source-to-target' experiment, the Integrated Beam Experiment (IBX). By combining the experience gained in the current separate beam experiments IBX would allow the integrated scientific study of the evolution of a single heavy ion beam at high current ({approx}1 A) through all sections of a possible heavy ion fusion accelerator: the injection, acceleration, compression, and beam focusing.This paper describes the main parameters and technology choices of the planned IBX experiment. IBX will accelerate singly charged potassium or argon ion beams up to 10 MeV final energy and a longitudinal beam compression ratio of 10, resulting in a beam current at target of more than 10 Amperes. Different accelerator cell design options are described in detail: Induction cores incorporating either room temperature pulsed focusing-magnets or superconducting magnets.

Leitner, M.A. [Ernest Orlando Lawrence Berkeley National Laboratory (United States); Celata, C.M. [Ernest Orlando Lawrence Berkeley National Laboratory (United States); Lee, E.P. [Ernest Orlando Lawrence Berkeley National Laboratory (United States); Logan, B.G. [Ernest Orlando Lawrence Berkeley National Laboratory (United States); Sabbi, G. [Ernest Orlando Lawrence Berkeley National Laboratory (United States); Waldron, W.L. [Ernest Orlando Lawrence Berkeley National Laboratory (United States); Barnard, J.J. [Lawrence Livermore National Laboratory (United States)

2003-09-15

354

Production of accelerating quad Airy beams and their optical characteristics.  

PubMed

Based on a geometric caustic argument and diffraction catastrophe theory, we generate a novel form of accelerating beams using a symmetric 3/2 phase-only pattern. Such beams can be called accelerating quad Airy beams (AQABs) because they look very much like four face-to-face combined Airy beams. Optical characteristics of AQABs are subsequently investigated. The research results show that the beams have axial-symmetrical and centrosymmetrical transverse intensity patterns and quasi-diffraction-free propagation features for their four main lobes while undergoing transverse shift along parabolic trajectories. Moreover, we also demonstrate that AQABs possess self-construction ability when local areas are blocked. The unique optical properties of these beams will make them useful tools for future scientific applications. PMID:24977608

Ren, Zhijun; Wu, Qiong; Shi, Yile; Chen, Chen; Wu, Jiangmiao; Wang, Hui

2014-06-16

355

Wave-particle interaction and peculiarities of propagation and emission of accelerated particles in solar flares  

NASA Astrophysics Data System (ADS)

Consequences of wave-particle interaction in the propagation and emission of accelerated particles in solar flares are considered. i. Strong diffusion energetic particles on small-scale waves (Trakhtengerts 1984) gives time delays of gamma ray line emission vs hard X-ray emission when electron and protons are accelerated simultaneously. ii. Anomalous propagation of relativistic electrons along the flare loop with velocity of 30 times less compared with light velocity (Yokoyama et al 2002) is explained in terms of the collective effects of interaction of electrons with plasma turbulence. A cloud of high-energetic electrons responsible for microwave emission generates whistler waves and a turbulent "wall" in the loop is formed. The electrons undergo strong resonant scattering and the emission front propagates with the wave phase velocity, which is much lower than particle velocity. iii. Absence of linear polarization (? 0.07%) in H? emission of some flares (Bianda et al 2005) is interpreted in terms of pitch-angle scattering of proton beams on small-scale Alfven waves. References Bianda M., Benz F.O., Stenflo J.O. et al 2005, A&A, 434, 1183 Trakhtengerts V.Yu. 1984, Relaxation of Plasma with Anisotropic Velocity Distribution, in A.A.Galeev and R.N.Sudan (eds.) Basic Plasma Physics II, North-Holland Physics Publishing Yokoyama T., Nakajima H., Shibasaki K, et al. 2002, ApJ, 576, L87

Stepanov, A. V.; Tsap, Yu. T.

2006-08-01

356

High transformer ratio drive beams for wakefield accelerator studies  

NASA Astrophysics Data System (ADS)

For wakefield based acceleration schemes, use of an asymmetric (or linearly ramped) drive bunch current profile has been predicted to enhance the transformer ratio and generate large accelerating wakes. We discuss plans and initial results for producing such bunches using the 20 to 23 GeV electron beam at the FACET facility at SLAC National Accelerator Laboratory and sending them through plasmas and dielectric tubes to generate transformer ratios greater than 2 (the limit for symmetric bunches). The scheme proposed utilizes the final FACET chicane compressor and transverse collimation to shape the longitudinal phase space of the beam.

England, R. J.; Ng, C.-K.; Frederico, J.; Hogan, M. J.; Litos, M.; Muggli, P.; Joshi, C.; An, W.; Andonian, G.; Mori, W.; Lu, W.

2012-12-01

357

High transformer ratio drive beams for wakefield accelerator studies  

SciTech Connect

For wakefield based acceleration schemes, use of an asymmetric (or linearly ramped) drive bunch current profile has been predicted to enhance the transformer ratio and generate large accelerating wakes. We discuss plans and initial results for producing such bunches using the 20 to 23 GeV electron beam at the FACET facility at SLAC National Accelerator Laboratory and sending them through plasmas and dielectric tubes to generate transformer ratios greater than 2 (the limit for symmetric bunches). The scheme proposed utilizes the final FACET chicane compressor and transverse collimation to shape the longitudinal phase space of the beam.

England, R. J.; Ng, C.-K.; Frederico, J.; Hogan, M. J.; Litos, M.; Muggli, P.; Joshi, C.; An, W.; Andonian, G.; Mori, W.; Lu, W. [SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Max Planck Institute for Physics, 80805 Munich (Germany); University of California Los Angeles, Los Angeles, CA 90095 (United States); Tsinghua University, Beijing (China)

2012-12-21

358

Beam profile effects on NPB (neutral particle beam) performance  

SciTech Connect

A comparison of neutral particle beam brightness for various neutral beam profiles indicates that the widely used assumption of a Gaussian profile may be misleading for collisional neutralizers. An analysis of available experimental evidence shows that lower peaks and higher tails, compared to a Gaussian beam profile, are observed out of collisional neutralizers, which implies that peak brightness is over estimated, and for a given NPB platform-to-target range, the beam current (power), dwell time or some combination of such engagement parameters would have to be altered to maintain a fixed dose on target. Based on the present analysis, this factor is nominally about 2.4 but may actually be as low as 1.8 or as high as 8. This is an important consideration in estimating NPB constellation performance in SDI engagement contexts. 2 refs., 6 figs.

LeClaire, R.J. Jr.

1988-03-01

359

Extraction of high-energy particle beams through the yoke of the synchrocyclotron magnet  

Microsoft Academic Search

A method of obtaining collimated beams of high-energy particles (in particular, pions) is described; this method makes use of the yoke of the synchrocyclotron magnet as the main shield against the direct radiation of the accelerator. The collimators, which are set into channels drilled in the yoke of the magnet, make it possible to obtain beams of pions with energies

A. E. Ignatenko; V. V. Krivitsky; A. I. Mukhin; B. Pontecorvo; A. A. Reut; K. I. Tarakanov

1956-01-01

360

Sources and acceleration of energetic particles in planetary magnetospheres  

NASA Technical Reports Server (NTRS)

Energetic particles in the magnetospheres of the solar system originate from various different sources, such as the solar wind, the planetary ionospheres as well as the moons and rings of the planetary systems. Important acceleration sites are the auroral regions, the magnetotail, and the equatorial regions of the magnetospheres where electric fields, wave-particle interactions, and magnetic pumping are among the major acceleration mechanisms proposed. Over the last decade mass- and charge-sensitive particle spectrometers on satellites and space probes have collected a wealth of information about the relative contribution of the various particle sources and the major acceleration processes to the energetic particle populations. Emphasis will be put on recent studies of the source populations and the acceleration processes in the Earth's auroral zones and magnetotail. Furthermore, the Jovian system with the largest magnetosphere and its unique mixture of particle sources with strong contributions from moons will be highlighted in some results from Ulysses.

Moebius, Eberhard

1994-01-01

361

Transformer ratio improvement for beam based plasma accelerators  

SciTech Connect

Increasing the transformer ratio of wakefield accelerating systems improves the viability of present novel accelerating schemes. The use of asymmetric bunches to improve the transformer ratio of beam based plasma systems has been proposed for some time[1, 2] but suffered from lack appropriate beam creation systems. Recently these impediments have been overcome [3, 4] and the ability now exists to create bunches with current profiles shaped to overcome the symmetric beam limit of R {<=} 2. We present here work towards experiments designed to measure the transformer ratio of such beams, including theoretical models and simulations using VORPAL (a 3D capable PIC code) [5]. Specifically we discuss projects to be carried out in the quasi-nonlinear regime [6] at the UCLA Neptune Laboratory and the Accelerator Test Facility at Brookhaven National Lab.

O'Shea, Brendan; Rosenzweig, James; Barber, Samuel; Fukasawa, Atsushi; Williams, Oliver; Muggli, Patric; Yakimenko, Vitaly; Kusche, Karl [University of California, Los Angeles, Department of Physics and Astronomy, Los Angeles, CA 90095 (United States); University of Southern California, Department of Electrical Engineering, Los Angeles, CA 90089 U.S.A. and Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Muenchen (Germany); Accelerator Test Facility, Brookhaven National Lab, Upton, NY, 11973 (United States)

2012-12-21

362

Transformer ratio improvement for beam based plasma accelerators  

NASA Astrophysics Data System (ADS)

Increasing the transformer ratio of wakefield accelerating systems improves the viability of present novel accelerating schemes. The use of asymmetric bunches to improve the transformer ratio of beam based plasma systems has been proposed for some time[1, 2] but suffered from lack appropriate beam creation systems. Recently these impediments have been overcome [3, 4] and the ability now exists to create bunches with current profiles shaped to overcome the symmetric beam limit of R <= 2. We present here work towards experiments designed to measure the transformer ratio of such beams, including theoretical models and simulations using VORPAL (a 3D capable PIC code) [5]. Specifically we discuss projects to be carried out in the quasi-nonlinear regime [6] at the UCLA Neptune Laboratory and the Accelerator Test Facility at Brookhaven National Lab.

O'Shea, Brendan; Rosenzweig, James; Barber, Samuel; Fukasawa, Atsushi; Williams, Oliver; Muggli, Patric; Yakimenko, Vitaly; Kusche, Karl

2012-12-01

363

Earth's Most Powerful Natural Particle Accelerator  

NASA Technical Reports Server (NTRS)

Thunderstorms launch antimatter, gamma rays, and highly energetic electrons and neutrons to the edge of space. This witches' brew of radiation is generated at the edge of the stratopause, by the strong electric fields associated with lightning discharges. In less than a quarter millisecond, an explosive feedback process takes an initial seed population of electrons, perhaps produced by cosmic rays from dying stars, and amplifies them a billion billion-fold in the rarefied air over high altitude thunderheads. The electrons generate gamma radiation as they travel through the stratosphere and lower mesosphere, momentarily brighter and of harder spectrum than cosmic gamma ray bursts. These electrons ultimately are absorbed by the atmosphere, but the gamma rays continue on, into the upper reaches of the atmosphere, where they in turn generate a new population of electrons, positrons, and energetic neutrons. These secondary electrons and positrons move along the magnetic field, and can reach near-earth space, streaming through the inner radiation belts, and possibly contributing to the trapped populations there. First postulated by Wilson in 1925, and serendipitously discovered by the Compton Gamma Ray Observatory in 1994 [Fishman et al.], these events, known as "Terrestrial Gamma ray Flashes" (TGFs), represent the most intense episodes of particle acceleration on or near the Earth, resulting in electrons with energies up to 100 MeV. Recent observations by the RHESSI [Smith et al., 2004], Fermi [Briggs et al., 2010], and AGILE [Tavani et al., 2011] satellites, and theoretical and computational modeling, have suggested that the relativistic runaway electron avalanche (RREA) mechanism [Gurevich, 1992], and important modifications, such as the relativistic feedback discharge (RFD) model [Dwyer 2012] can best explain the observations at present. In these models, strong thunderstorm electric fields drive seed electrons, generated from cosmic ray interactions, into a runaway discharge, in which the seed electrons continually gain energy from the electric field, creating a host of secondaries as they interact with the background atmospheric gas. The feedback mechanisms include backwards-propagating positrons and gamma rays, which then can generate new "seed" electrons at the base of the acceleration region, and themselves generate further avalanche chain reactions, greatly amplifying the initial seed population. All these processes happen in the stratosphere, in the altitude range near 15-20 km, where the electric fields and mean free paths are appropriate to allow the discharge to develop.

Rowland, Doug

2012-01-01

364

Extensions of MAD Version 8 to Include Beam Acceleration  

SciTech Connect

In this paper, the authors describe modifications to MAD version 8.23 to include linear accelerator cavities and beam acceleration. An additional energy variable has been added which is modified as the beam passes through LCAV elements (linear accelerator cavities) and can be used as a constraint in matching commands. The calculation of the beta functions and phase advance is consistent with that in other codes that treat acceleration such as TRANSPORT or DIMAD. These modifications allow this version of MAD to be used for the design and modeling of linacs and the authors present examples from the Next Linear Collider design as well as a muon acceleration complex. The code is available from CERN or SLAC.

Raubenheimer, Tor O

2000-07-20

365

Shock tube spherical particle accelerating study for drag coefficient determination  

Microsoft Academic Search

.   An original particle accelerating technique has been developed for a shock tube. The trajectories of calibrated spherical\\u000a particles and in diameter have been measured by the multiple exposure shadowgraph technique coupled with a high speed drum camera. Both\\u000a particle velocity and acceleration, deduced from the experimental trajectories, allow the determination of the drag coefficients\\u000a for different, subsonic and supersonic,

C. Devals; G. Jourdan; J.-L. Estivalezes; E. E. Meshkov; L. Houas

2003-01-01

366

Soviet exoatmospheric neutral particle beam research  

Microsoft Academic Search

This technical assessment was performed by a panel of eight U.S. scientists and engineers who are familiar with Soviet research through their own research experience, their knowledge of the published scientific literature and conference proceedings, and personal contacts with Soviet scientists and other foreign colleagues. Most of the technical components of a neutral particle beam generating system including the ion

J. E. Leiss; R. H. Abrams; K. W. Ehlers; J. A. Farrell; G. H. Gillespie; R. A. Jameson; D. Keefe; R. K. Parker

1988-01-01

367

Secondary gamma radiation from neutral particle beams  

Microsoft Academic Search

The results of a proton?induced gamma?ray emission experiment are presented. Such data can be used to simulate the effects of a neutral particle beam within the context of proposed midcourse?phase target discrimination schemes. A summary of the calculations is presented in order to support the general conclusion that the physical limitations on such a system are prohibitive.

Guy A. Letteer; John A. Jungerman; Carlos M. Castaneda

1991-01-01

368

Single event upset from neutral particle beams  

SciTech Connect

Are single event upsets an important vulnerability or lethality issue for strategic systems Neutron-induced single events have become a part of the vulnerability analysis for nuclear weapon environments, but there has been no serious consideration of proton-induced single events from neutron particle beam environments. Is this appropriate This paper examines this concept.

Browning, J.S. (Sandia National Labs., Albuquerque, NM (USA))

1989-01-01

369

Controlling the Betatron Oscillations of Accelerated Electron Beams by Temporally-Asymmetric Laser Pulses in LWFA  

NASA Astrophysics Data System (ADS)

We investigated the betatron oscillations of accelerated electron beams in laser wakefield acceleration by temporally-asymmetric laser pulses via two-dimensional particle-in-cell simulations. By using an asymmetric laser pulse having sharp rising and slow falling time scales, the accelerated electron beam can interact directly with the falling part of the laser field and the electrons will have transverse oscillations due to the phase-slip with the laser field. This oscillation can be matched with the betatron oscillation by the focusing force of the ions, which results in large transverse oscillation amplitude due to the resonance between two frequencies. Furthermore, the electron beam can be micro-bunched at the laser wavelength, which may provide the possibility for generation of a coherent synchrotron radiation. In this presentation, details of the phenomena are shown.

Nam, Inhyuk; Hur, Min Sup; Uhm, Han Sup; Hafz, Nasr A. M.; Suk, Hyyong

2011-11-01

370

Neutral particle beam alternative concept for ITER  

SciTech Connect

An analysis of an ITER neutral particle beam system is presented. The analysis covers the neutralizer, ion dumps, pumping, and geometric aspects. The US beam concept for ITER consists of three or four clusters of beamlines delivering approximately 80 MW total of 1.6-MeV deuterium to three or four reactor ports. Each cluster has three self-contained beamlines featuring plasma neutralizers and electrostatic ion dumps. In this study, each of the beamlines has two source assemblies with separate gas neutralizers and magnetic ion dumps. Deuterium is injected into the gas neutralizers by a separate system. Saddle-shaped copper coils augment the tokamak poloidal field to turn the charged particles into the ion dumps. The gas flow from the source, neutralizer, and ion dump is pumped by regenerable cryopanels. The effect of the port between the TF coils and the beam injection angle on the plasma footprint was studied.

Sedgley, D.; Brook, J.; Luzzi, T.; Deutsch, L.

1989-03-01

371

Particle Acceleration in Dissipative Pulsar Magnetospheres  

NASA Technical Reports Server (NTRS)

Pulsar magnetospheres represent unipolar inductor-type electrical circuits at which an EM potential across the polar cap (due to the rotation of their magnetic field) drives currents that run in and out of the polar cap and close at infinity. An estimate ofthe magnitude of this current can be obtained by dividing the potential induced across the polar cap V approx = B(sub O) R(sub O)(Omega R(sub O)/c)(exp 2) by the impedance of free space Z approx eq 4 pi/c; the resulting polar cap current density is close to $n {GJ} c$ where $n_{GJ}$ is the Goldreich-Julian (GJ) charge density. This argument suggests that even at current densities close to the GJ one, pulsar magnetospheres have a significant component of electric field $E_{parallel}$, parallel to the magnetic field, a condition necessary for particle acceleration and the production of radiation. We present the magnetic and electric field structures as well as the currents, charge densities, spin down rates and potential drops along the magnetic field lines of pulsar magnetospheres which do not obey the ideal MHD condition $E cdot B = 0$. By relating the current density along the poloidal field lines to the parallel electric field via a kind of Ohm's law $J = sigma E_{parallel}$ we study the structure of these magnetospheres as a function of the conductivity $sigma$. We find that for $sigma gg OmegaS the solution tends to the (ideal) Force-Free one and to the Vacuum one for $sigma 11 OmegaS. Finally, we present dissipative magnetospheric solutions with spatially variable $sigma$ that supports various microphysical properties and are compatible with the observations.

Kazanas, Z.; Kalapotharakos, C.; Harding, A.; Contopoulos, I.

2012-01-01

372

Possibility for ultra-bright electron beam acceleration in dielectric wakefield accelerators  

NASA Astrophysics Data System (ADS)

We describe a conceptual proposal to combine the Dielectric Wakefield Accelerator (DWA) with the Emittance Exchanger (EEX) to demonstrate a high-brightness DWA with a gradient of above 100 MV/m and less than 0.1% induced energy spread in the accelerated beam. We currently evaluate the DWA concept as a performance upgrade for the future LANL signature facility MaRIE with the goal of significantly reducing the electron beam energy spread. The preconceptual design for MaRIE is underway at LANL, with the design of the electron linear accelerator being one of the main research goals. Although generally the baseline design needs to be conservative and rely on existing technology, any future upgrade would immediately call for looking into the advanced accelerator concepts capable of boosting the electron beam energy up by a few GeV in a very short distance without degrading the beam's quality. Scoping studies have identified large induced energy spreads as the major cause of beam quality degradation in high-gradient advanced accelerators for free-electron lasers. We describe simulations demonstrating that trapezoidal bunch shapes can be used in a DWA to greatly reduce the induced beam energy spread, and, in doing so, also preserve the beam brightness at levels never previously achieved. This concept has the potential to advance DWA technology to a level that would make it suitable for the upgrades of the proposed Los Alamos MaRIE signature facility.

Simakov, Evgenya I.; Carlsten, Bruce E.; Shchegolkov, Dmitry Yu.

2012-12-01

373

Long pulse H{sup -} ion beam acceleration in MeV accelerator  

SciTech Connect

A multiaperture multigrid accelerator called ''MeV accelerator'' has been developed for neutral beam injection system of international thermonuclear experimental reactor. In the present work, long pulse H{sup -} ion beam acceleration was performed by the MeV accelerator equipped with new water-cooled grids. At present, the pulse length was extended to 5 s for the beams of 750 keV, 221 mA, and 10 s for the beams of 600 keV, 158 mA. Energy density, defined as products of beam energy (keV), current (mA), and pulse (s) divided by aperture area (m{sup 2}), increased more than one order of magnitude higher compared with original MeV accelerator without water cooling in its grids. At higher energy and current, the grid was melted by beam deflection. Due to this grid melting, breakdowns occurred between the grids, and hence, the pulse length was limited. Beam deflection will be compensated by aperture displacement in next experiment.

Taniguchi, M.; Mizuno, T.; Umeda, N.; Kashiwagi, M.; Watanabe, K.; Tobari, H.; Kojima, A.; Tanaka, Y.; Dairaku, M.; Hanada, M.; Sakamoto, K.; Inoue, T. [Fusion Research and Development Directorate, Japan Atomic Energy Agency, 801-1 Mukoyama, Naka, Ibaraki 311-0193 (Japan)

2010-02-15

374

Possibility for ultra-bright electron beam acceleration in dielectric wakefield accelerators  

SciTech Connect

We describe a conceptual proposal to combine the Dielectric Wakefield Accelerator (DWA) with the Emittance Exchanger (EEX) to demonstrate a high-brightness DWA with a gradient of above 100 MV/m and less than 0.1% induced energy spread in the accelerated beam. We currently evaluate the DWA concept as a performance upgrade for the future LANL signature facility MaRIE with the goal of significantly reducing the electron beam energy spread. The preconceptual design for MaRIE is underway at LANL, with the design of the electron linear accelerator being one of the main research goals. Although generally the baseline design needs to be conservative and rely on existing technology, any future upgrade would immediately call for looking into the advanced accelerator concepts capable of boosting the electron beam energy up by a few GeV in a very short distance without degrading the beam's quality. Scoping studies have identified large induced energy spreads as the major cause of beam quality degradation in high-gradient advanced accelerators for free-electron lasers. We describe simulations demonstrating that trapezoidal bunch shapes can be used in a DWA to greatly reduce the induced beam energy spread, and, in doing so, also preserve the beam brightness at levels never previously achieved. This concept has the potential to advance DWA technology to a level that would make it suitable for the upgrades of the proposed Los Alamos MaRIE signature facility.

Simakov, Evgenya I.; Carlsten, Bruce E.; Shchegolkov, Dmitry Yu. [Los Alamos National Laboratory, PO Box 1663, Los Alamos, NM 87545 (United States)

2012-12-21

375

Numerical modeling of relativistic particle shock acceleration  

NASA Astrophysics Data System (ADS)

The shock acceleration mechanism is invoked to explain non-thermal cosmic rays in Supernova Remnants, Active Galactic Nuclei and Gamma Ray Bursts jets. Especially, the importance of relativistic shock acceleration in extragalactic sources is a recurring theme raising a significant interest in the research community. We will briefly overview the shock acceleration mechanism and we will address the properties of non-relativistic and relativistic shocks, particularly focusing on relativistic simulation studies.

Meli, A.

2011-08-01

376

Long-pulse beam acceleration of MeV-class H(-) ion beams for ITER NB accelerator.  

PubMed

In order to realize neutral beam systems in International Thermonuclear Experimental Reactor whose target is to produce a 1 MeV, 200 A/m(2) during 3600 s D(-) ion beam, the electrostatic five-stages negative ion accelerator so-called "MeV accelerator" has been developed at Japan Atomic Energy Agency. To extend pulse length, heat load of the acceleration grids was reduced by controlling the ion beam trajectory. Namely, the beam deflection due to the residual magnetic field of filter magnet was suppressed with the newly developed extractor with a 0.5 mm off-set aperture displacement. The new extractor improved the deflection angle from 6 mrad to 1 mrad, resulting in the reduction of direct interception of negative ions from 23% to 15% of the total acceleration power, respectively. As a result, the pulse length of 130 A/m(2), 881 keV H(-) ion beam has been successfully extended from a previous value of 0.4 s to 8.7 s. This is the first long pulse negative ion beam acceleration over 100 MW/m(2). PMID:24593581

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

2014-02-01

377

Problems Connected with Particle Extraction from Superhigh-Energy Accelerators.  

National Technical Information Service (NTIS)

With the purpose of increasing the operating efficiency of an accelerator with an energy of the order of thousands of GeV, main problems are considered which arise when extracting a proton beam from such an accelerator. Estimates of radiation heating of w...

V. N. Lebedev N. V. Mokhov K. P. Myznikov Y. S. Fedotov

1980-01-01

378

Acceleration of energetic particles which accompany coronal mass ejections  

NASA Technical Reports Server (NTRS)

The causal association of major solar particle events seen at earth with coronal mass ejections (CME's), and not with solar flares, is discussed. Evidence that led to the demise of the flare dominated paradigm for major solar energetic particle events are described. The possibility of distinguishing particles from impulsive and gradual events using only observations is described. Particle acceleration at the CME level is discussed. Multi-spacecraft observations of CME events are described. Concerning the interplanetary CME, bidirectional proton events are discussed. Conclusions from progress in understanding the characteristics of solar energetic particles and their relation to the physical mechanisms of acceleration are given.

Reames, Donald V.

1994-01-01

379

Induction accelerators and free-electron lasers at LLNL: Beam Research Program  

SciTech Connect

Linear induction accelerators have been developed to produce pulses of charged particles at voltages exceeding the capabilities of single-stage, diode-type accelerators and at currents too high rf accelerators. In principle, one can accelerate charged particles to arbitrarily high voltages using a multistage induction machine. The advent of magnetic pulse power systems makes sustained operation at high repetition rates practical, and high-average-power capability is very likely to open up many new applications of induction machines. In Part A of this paper, we survey the US induction linac technology, emphasizing electron machines. We also give a simplified description of how induction machines couple energy to the electron beam to illustrate many general issues that designers of high-brightness and high-average-power induction linacs must consider. We give an example of the application of induction accelerator technology to the relativistic klystron, a power source for high-gradient accelerators. In Part B we address the application of LIAs to free-electron lasers. The multikiloampere peak currents available from linear induction accelerators make high-gain, free-electron laser amplifier configurations feasible. High extraction efficiencies in a single mass of the electron beam are possible if the wiggler parameters are appropriately ''tapered'', as recently demonstrated at millimeter wavelengths on the 4-MeV ELF facility. Key issues involved in extending the technology to shorter wavelengths and higher average powers are described. Current FEL experiments at LLNL are discussed. 5 refs., 16 figs.

Briggs, R.J.

1989-02-15

380

Shock acceleration of energetic particles in the heliosphere  

NASA Technical Reports Server (NTRS)

The apparent distinction between 'V x B' and 'Fermi' mechanisms is clarified in a discussion of the theory of the shock acceleration of energetic particles which restricts attention to those cases where the energetic particles do not themselves influence the given shock structure. The theory is applied to the acceleration of energetic particles in corotating interaction regions (CIR) in the solar wind, where particles are accelerated at either the forward and reverse shocks which bound the CIR by being compressed between the shock fronts and magnetic irregularities upstream of the shocks, or by being compressed between upstream irregularities and those downstream from the shocks. The model is shown to account for the observed exponential spectra at the earth, observed spectra behavior with radial distance and radial intensity gradients, and differences in spectra intensity at the forward and reverse shocks. Energy spectra are also calculated for the shock acceleration of energetic particles in large solar flare events.

Lee, M. A.; Fisk, L. A.

1982-01-01

381

Shock acceleration of energetic particles in the heliosphere  

NASA Astrophysics Data System (ADS)

The apparent distinction between 'V x B' and 'Fermi' mechanisms is clarified in a discussion of the theory of the shock acceleration of energetic particles which restricts attention to those cases where the energetic particles do not themselves influence the given shock structure. The theory is applied to the acceleration of energetic particles in corotating interaction regions (CIR) in the solar wind, where particles are accelerated at either the forward and reverse shocks which bound the CIR by being compressed between the shock fronts and magnetic irregularities upstream of the shocks, or by being compressed between upstream irregularities and those downstream from the shocks. The model is shown to account for the observed exponential spectra at the earth, observed spectra behavior with radial distance and radial intensity gradients, and differences in spectra intensity at the forward and reverse shocks. Energy spectra are also calculated for the shock acceleration of energetic particles in large solar flare events.

Lee, M. A.; Fisk, L. A.

1982-03-01

382

Shocks and particle acceleration in SNRs: theoretical aspects  

Microsoft Academic Search

Nonthermal particle injection and acceleration in supernova shocks are expected to be efficient processes at different evolutional stages of SNRs. Nonlinear wave-particle interactions being the governing process of the SNR collisionless shock formation are responsible for both shock heating and compression of the thermal gas as well as for the creation of a high energy nonthermal particle population. We discuss

A. Bykov

2002-01-01

383

High energy particle accelerators that can fit on a (large) tabletop by using lasers  

NASA Astrophysics Data System (ADS)

Accelerators are essential tools of discovery and have many practical uses. At the forefront of accelerator technology are the machines that deliver beams for particle physics, for synchrotron and free electron based radiation sources. The technology that drives these accelerators is extremely sophisticated but is limited by the maximum sustainable accelerating field. This impacts the size and cost of the device. More than two decades ago, lasers were proposed as power source for driving novel accelerators based on plasmas as the accelerating medium. An overview will be presented of what these devices can produce to date, including the 2004 demonstration of high quality electron beams [1] and the 2006 demonstration of GeV class beams from a 3 cm long accelerating structure [2]. We then discuss the key challenges for broad applicability of the technology and our goal of making a laser accelerator driven a VUV/soft x-ray free electron laser. [1] C.G.R. Geddes et al., Nature 431, 538-541 (2004); S.P.D. Mangles et al., ibid 535-538; J. Faure et al., ibid. 541-544. [2] W.P. Leemans et al., Nature Physics 2, 696-699 (2006).

Leemans, Wim

2008-04-01

384

Particle acceleration using the Vulcan Petawatt laser  

Microsoft Academic Search

Using the upgraded Vulcan Petawatt laser at 3×1020 Wcm-2 intensities, target interactions and acceleration in a gas jet were studied. Electron spectra with energies up to 240 MeV were detected. Indications of a new acceleration regime, which results in a nonMaxwellian distribution were observed.

D. Neely; K. Krushelnick; S. Mangles; R. Clarke; J. Collier; A. E. Dangor; C. N. Danson; R. D. Edwards; S. Fritzler; A. Gopal; P. Hatton; R. Heathcote; C. Hernandez-Gomez; K. W. D. Ledingham; P. McKenna; Z. Najmudin; B. Walton; M. Wei

2003-01-01

385

Relativistic particle acceleration using lasers and plasmas  

NASA Astrophysics Data System (ADS)

Since the pioneering work of Tajima and Dawson on the laser electron accelerator, experiments on the excitation of high-amplitude plasma waves by beat-wave, photon wakefield and self-resonant wakefield have been performed in plasmas and give evidence of electron acceleration in the range 1 - 100 MeV for distances of less than one centimetre. Electrons, either from the plasma itself, or injected from outside, are accelerated to these relativistic energies by the longitudinal electric field of the laser-excited plasma wave whose phase velocity is close to the speed of light. After a short survey of the excitation mechanism of this relativistic plasma wave, the scaling laws which link the electric field of the plasma wave, the energy gain of accelerated electrons and the acceleration length to the parameters of the laser will be recalled. Then, limits for the energy of accelerated electrons will be given in the case of passing and trapped electrons as well as in the case of wavebreaking. These classical results will be compared with recent experimental results of electron acceleration in CO2 and Nd, beat-wave, as well as for self-resonant wakefield. Future experiments on photon wakefield will be discussed. Relevant work performed to improve the energy gain of acceleration schemes such as light channelling by preformed plasmas or by relativistic effects will be discussed.

Matthieussent, G.

1997-05-01

386

Shock Surface Undulation and Particle Acceleration at Oblique Shocks  

NASA Astrophysics Data System (ADS)

Considering the average Parker spiral magnetic field configuration, CME-driven interplanetary (IP) shocks within 1 AU should have oblique portions over much of their domain. Indeed, CME-driven shocks observed close to Earth are often oblique. However, it is well known that the standard diffusive shock acceleration mechanism, which relies on self-consistent wave generation via upstream propagating ions and their scattering, becomes increasingly inefficient with greater shock normal angle. Not only is a higher threshold energy required for the ions to leave the shock upstream, but also, approximately-parallel propagating waves are more quickly convected back into the shock, and the growth rate for waves propagating normal to the shock (the ones with the largest convective growth) decreases. As a result, typical, small-scale hybrid simulations of oblique shocks only show a dilute upstream beam, similar to what is often observed at the oblique Earth's bow shock - and no scattered, highly-energized ions. On the other hand, there are many "energetic storm particle" (ESP) events associated with oblique shocks that have significant fluxes of energetic ions. Recently, we have found that when run for a long time, our hybrid simulations (kinetic ions, electron fluid) show that the initial, weak beam is sufficient to generate compressive, steepening upstream waves. These waves are capable of disturbing the shock surface, resulting in an undulation that is propagating along the surface and growing in amplitude over time. The process is akin to that of the well-known reformation occurring at sufficiently strong quasi-parallel shocks. However, here the perturbations require at least two dimensions, show a strong spatial correlation, and travel along the shock surface. This process not only leads to enhanced ion acceleration, but also means that the shock characteristics are difficult to pinpoint, observationally: both the local jumps and the shock normal angle are highly variable. Shock undulation is also of interest to electron acceleration, since the undulated surface gives locally much larger shock normal angles and provides multiple mirroring and escape opportunities to accelerated electrons. We compare our simulations with a set of oblique shocks that we compiled from ACE observations, and discuss the results in the context of developing quantitative models of the flux and spectrum of energetic ions at IP shocks.

Krauss-Varban, D.; Li, Y.; Luhmann, J. G.

2006-12-01

387

Accelerator summary  

NASA Astrophysics Data System (ADS)

A summary of the accelerator topics (CW electron accelerators, heavy ion colliders, kaon factories, polarized proton beams, and cooling rings) discussed in the 1984 conference on ``Intersections Between Particle and Nuclear Physics'' (Steamboat Springs) is presented. (AIP)

Mills, F. E.

1984-11-01

388

Accelerator summary  

SciTech Connect

A summary of the accelerator topics (CW electron accelerators, heavy ion colliders, kaon factories, polarized proton beams, and cooling rings) discussed in the 1984 conference on ''Intersections Between Particle and Nuclear Physics'' (Steamboat Springs) is presented. (AIP)

Mills, F.E.

1984-11-15

389

On Particle Acceleration Rate in Gamma-Ray Burst Afterglows  

NASA Astrophysics Data System (ADS)

It is well known that collisionless shocks are major sites of particle acceleration in the universe, but the details of the acceleration process are still not well understood. The particle acceleration rate, which can shed light on the acceleration process, is rarely measured in astrophysical environments. Here, we use observations of gamma-ray burst (GRB) afterglows, which are weakly magnetized relativistic collisionless shocks in ion-electron plasma, to constrain the rate of particle acceleration in such shocks. We find, based on X-ray and GeV afterglows, an acceleration rate that is most likely very fast, approaching the Bohm limit, when the shock Lorentz factor is in the range of ? ~ 10-100. In that case X-ray observations may be consistent with no amplification of the magnetic field in the shock upstream region. We examine the X-ray afterglow of GRB 060729, which is observed for 642 days showing a sharp decay in the flux starting about 400 days after the burst, when the shock Lorentz factor is ~5. We find that inability to accelerate X-ray-emitting electrons at late time provides a natural explanation for the sharp decay, and that also in that case acceleration must be rather fast, and cannot be more than a 100 times slower than the Bohm limit. We conclude that particle acceleration is most likely fast in GRB afterglows, at least as long as the blast wave is ultrarelativistic.

Sagi, Eran; Nakar, Ehud

2012-04-01

390

Accelerator systems and instrumentation for the NuMI neutrino beam  

NASA Astrophysics Data System (ADS)

The Neutrinos at the Main Injector (NuMI) neutrino beam facility began operating at the Fermi National Accelerator Laboratory in 2005. NuMI produces an intense, muon-neutrino beam to a number of experiments. Fore most of these experiments is MINOS---the Main Injector Neutrino Oscillation Search---that uses two neutrino detectors in the beam, one at Fermilab and one in northern Minnesota, to investigate the phenomenon of neutrino oscillations. NuMI is a conventional, horn-focused neutrino beam. It is designed to accept a 400 kW, 120 GeV proton beam from the Fermilab Main Injector accelerator. The proton beam is steered onto a target, producing a secondary beam of mesons which are focused into a long evacuated volume where they decay to muons and neutrinos. Pulsed toroidal magnets (horns) focus an adjustable meson momentum range. Design of the beamline and its components is challenged by the 400 kW average proton beam power. To achieve such high proton power, the Fermilab Main Injector (MI) must store and accelerate ˜ 4x1013 protons per acceleration cycle. This requires the MI to be loaded with 6 or more batches of protons from the 8 GeV Booster accelerator. Such multiple-batch injection involves a synchronization of the two machines not previously required by the Fermilab accelerators. In this dissertation, we investigate timing errors that can arise between the two accelerators, and a feedback system which enables multiple Booster transfers into the Main Injector without significant loss of beam. Using this method of synchronous transfer, the Main Injector has delivered as many as 3x1013 protons per pulse to the NuMI beam. The instrumentation to assess the quality of the neutrino beam includes arrays of radiation-tolerant ionization chambers downstream of the decay volume. These arrays detect the remnant hadrons and tertiary muons produced with the neutrinos. This thesis discusses measurements using the arrays, including diagnostics of potential beam errors and initial alignment of the beamline elements. In addition, we describe theoretical calculations and experimental tests which demonstrate that the ionization chambers can withstand the intense particle fluxes in the beamline without signal loss due to space-charge build up in the detectors.

Zwaska, Robert Miles

391

Plasma flow and fast particles in a hypervelocity accelerator - A color presentation. [micrometeoroid simulation  

NASA Technical Reports Server (NTRS)

A new concept for particle acceleration for micrometeoroid simulation was developed at NASA Marshall Space Flight Center, using a high-density self-luminescent fast plasma flow to accelerate glass beads (with a diameter up to 1.0 mm) to velocities between 15-20 km/sec. After a short introduction to the operation of the hypervelocity range, the eight-converter-camera unit used for the photographs of the plasma flow and the accelerated particles is described. These photographs are obtained with an eight-segment reflecting pyramidal beam splitter. Wratten filters were mounted between the beam splitter and the converter tubes of the cameras. The photographs, which were recorded on black and white film, were used to make the matrices for the dye-color process, which produced the prints shown.

Igenbergs, E. B.; Cour-Palais, B.; Fisher, E.; Stehle, O.

1975-01-01

392

Beam acceleration in plasma focus device  

Microsoft Academic Search

The proton beam emission from the small 8kJ plasma focus device operated with the H2 filling was analyzed. Maximum energy and yield were obtained using NTD. The fast protons were registered with the energy up to 500keV using the polycarbonate absorbers with the different thickness.

R. Antanasijevi?; R. Banjanac; A. Dragi?; Z. Mari?; J. Stanojevi?; V. Udovi?i?; J. Vukovi?

2001-01-01

393

Particle Simulations of a Linear Dielectric Wall Proton Accelerator  

SciTech Connect

The dielectric wall accelerator (DWA) is a compact induction accelerator structure that incorporates the accelerating mechanism, pulse forming structure, and switch structure into an integrated module. The DWA consists of stacked stripline Blumlein assemblies, which can provide accelerating gradients in excess of 100 MeV/meter. Blumleins are switched sequentially according to a prescribed acceleration schedule to maintain synchronism with the proton bunch as it accelerates. A finite difference time domain code (FDTD) is used to determine the applied acceleration field to the proton bunch. Particle simulations are used to model the injector as well as the accelerator stack to determine the proton bunch energy distribution, both longitudinal and transverse dynamic focusing, and emittance growth associated with various DWA configurations.

Poole, B R; Blackfield, D T; Nelson, S D

2007-06-12

394

Driven response of a trapped particle beam  

SciTech Connect

The dynamics of a metastable beam of particles injected'' into artificially excited resonance islands in the Fermilab Tevatron is studied. Evolution of the captured beam distribution is measured by an externally detectable coherent signal. Dynamical partitions observed in the control space of amplitude and tune of a focusing modulation are consistent with an equivalent mode of an ensemble of driven gravity pendula. The model's single parameter, the island tune {ital Q}{sub {ital I}} of small oscillations, is inferred as the central frequency of resonant detrapping under this weak drive.

Satogata, T.; Chen, T.; Cole, B.; Finley, D.; Gerasimov, A.; Goderre, G.; Harrison, M.; Johnson, R.; Kourbanis, I.; Manz, C.; Merminga, N.; Michelotti, L.; Peggs, S.; Pilat, F.; Pruss, S.; Saltmarsh, C.; Saritepe, S.; Talman, R.; Trahern, C.G.; Tsironis, G. (Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States) Newman Laboratory of Nuclear Studies, Cornell University, Ithaca, New York 14853 (United States) SCC Laboratory, Dallas, Texas 75237 (United States) Brookhaven National Laboratory, Upton, New York 11973 (United States) Stanford Linear Accelerator Center, Stanford, California 94305 (United States) Physics Department, University of North Texas, Denton, Texas 76203 (United States))

1992-03-23

395

GeV electron beams from a cm-scale accelerator  

SciTech Connect

GeV electron accelerators are essential to synchrotron radiation facilities and free electron lasers, and as modules for high-energy particle physics. Radio frequency based accelerators are limited to relatively low accelerating fields (10-50 MV/m) and hence require tens to hundreds of meters to reach the multi-GeV beam energies needed to drive radiation sources, and many kilometers to generate particle energies of interest to the frontiers of high-energy physics.Laser wakefield accelerators (LWFA) in which particles are accelerated by the field of a plasma wave driven by an intense laser pulse produce electric fields several orders of magnitude stronger (10-100 GV/m) and so offer the potential of very compact devices. However, until now it has not been possible to maintain the required laser intensity, and hence acceleration, over the several centimeters needed to reach GeV energies.For this reason laser-driven accelerators have to date been limited to the 100 MeV scale. Contrary to predictions that PW-class lasers would be needed to reach GeV energies, here we demonstrate production of a high-quality electron beam with 1 GeV energy by channeling a 40 TW peak power laser pulse in a 3.3 cm long gas-filled capillary discharge waveguide. We anticipate that laser-plasma accelerators based on capillary discharge waveguides will have a major impact on the development of future femtosecond radiation sources such as x-ray free electron lasers and become a standard building block for next generation high-energy accelerators.

Leemans, W.P.; Nagler, B.; Gonsalves, A.J.; Toth, C.; Nakamura,K.; Geddes, C.G.R.; Esarey, E.B.; Schroeder, C.; Hooker, S.M.

2006-05-04

396

Charged-particle acceleration in braking plasma jets  

NASA Astrophysics Data System (ADS)

In this paper we describe the mechanism of the charged particle acceleration in space plasma systems. We consider the interaction of nonrelativistic particles with a sub-Alfvenic plasma jet originated from the magnetic reconnection. The sharp front with increased magnetic field amplitude forms in the jet leading edge. Propagation of the jet in the inhomogeneous background plasma results in front braking. We show that particles can interact with this front in a resonance manner. Synchronization of particle reflections from the front and the front braking provides the stable trapping of particles in the vicinity of the front. This trapping supports the effective particle acceleration along the front. The mechanism of acceleration is potentially important due to the prevalence of the magnetic reconnection in space and astrophysical plasmas.

Artemyev, A. V.

2014-03-01

397

H-mode Accelerating Structures with PMQ Focusing for Low-Beta Beams  

SciTech Connect

We report on results of the project developing high-efficiency normal-conducting RF accelerating structures based on inter-digital H-mode (IH) cavities and the transverse beam focusing with permanent-magnet quadrupoles (PMQ), for beam velocities in the range of a few percent of the speed of light. The shunt impedance of IH-PMQ structures is 10-20 times higher than that of a conventional drift-tube linac, while the transverse size is 4-5 times smaller. The H-PMQ accelerating structures following a short RFQ can be used both in the front end of ion linacs or in stand-alone applications. Results of the combined 3-D modeling -- electromagnetic computations, beam-dynamics simulations with high currents, and thermal-stress analysis -- for a full IH-PMQ accelerator tank are presented. The accelerating field profile in the tank is tuned to provide the best propagation of a 50-mA deuteron beam using coupled iterations of EM and beamdynamics modeling. Multi-particle simulations withParmela and CST Particle Studio have been used to confirm the design. Measurement results of a cold model of the IH-PMQ tank are presented.

Kurennoy, Sergey S. [Los Alamos National Laboratory; O'Hara, James F. [Los Alamos National Laboratory; Olivas, Eric R. [Los Alamos National Laboratory; Rybarcyk, Lawrence J. [Los Alamos National Laboratory

2011-01-01

398

A microsecond-pulsewidth, intense, light-ion beam accelerator  

SciTech Connect

A relatively long-pulsewidth (0.1-1 {mu}s) intense ion beam accelerator has been built for materials processing applications. An applied-B{sub r}, magnetically-insulated extraction ion diode with dielectric flashover ion source is installed directly onto the output of a 1.2-MV, 300-kJ Marx generator. Initial operation of the accelerator at 0.4 MV indicates satisfactory performance without the need for additional pulse-shaping.

Rej, D.J.; Bartsch, R.R.; Davis, H.A.; Greenly, J.B.; Waganaar, W.J.

1993-07-01

399

Beam dynamics simulation of the Spallation Neutron Source linear accelerator  

Microsoft Academic Search

The accelerating structure for Spallation Neutron Source (SNS) consists of a radio-frequency-quadrupole-linac (RFQ), a drift-tube-linac (DTL), a coupled-cavity-drift-tube-linac (CCDTL), and a coupled-cavity-linac (CCL). The linac is operated at room temperature. The authors discuss the detailed design of linac which accelerates an H⁻ pulsed beam coming out from RFQ at 2.5 MeV to 1000 MeV. They show a detailed transition from

H. Takeda; J. H. Billen; T. S. Bhatia

1998-01-01

400

Particle-in-cell simulations of plasma accelerators and electron-neutral collisions  

SciTech Connect

We present 2-D simulations of both beam-driven and laser-driven plasma wakefield accelerators, using the object-oriented particle-in-cell code XOOPIC, which is time explicit, fully electromagnetic, and capable of running on massively parallel supercomputers. Simulations of laser-driven wakefields with low ({approx}10{sup 16} W/cm{sup 2}) and high ({approx}10{sup 18} W/cm{sup 2}) peak intensity laser pulses are conducted in slab geometry, showing agreement with theory and fluid simulations. Simulations of the E-157 beam wakefield experiment at the Stanford Linear Accelerator Center, in which a 30 GeV electron beam passes through 1 m of preionized lithium plasma, are conducted in cylindrical geometry, obtaining good agreement with previous work. We briefly describe some of the more significant modifications of XOOPIC required by this work, and summarize the issues relevant to modeling relativistic electron-neutral collisions in a particle-in-cell code.

Bruhwiler, David L.; Giacone, Rodolfo E.; Cary, John R.; Verboncoeur, John P.; Mardahl, Peter; Esarey, Eric; Leemans, W.P.; Shadwick, B.A.

2001-10-01

401

A 2D Particle in Cell model for ion extraction and focusing in electrostatic accelerators.  

PubMed

Negative ions are fundamental to produce intense and high energy neutral beams used to heat the plasma in fusion devices. The processes regulating the ion extraction involve the formation of a sheath on a scale comparable to the Debye length of the plasma. On the other hand, the ion acceleration as a beam is obtained on distances greater than ?D. The paper presents a model for both the phases of ion extraction and acceleration of the ions and its implementation in a numerical code. The space charge of particles is deposited following usual Particle in Cell codes technique, while the field is solved with finite element methods. Some hypotheses on the beam plasma transition are described, allowing to model both regions at the same time. The code was tested with the geometry of the NIO1 negative ions source, and the results are compared with existing ray tracing codes and discussed. PMID:24593445

Veltri, P; Cavenago, M; Serianni, G

2014-02-01

402

Using Nonlinear RF Acceleration for FEL Beam Conditioning  

SciTech Connect

We consider a new approach to condition an electron beam using nonlinear effects in the RF field. We demonstrate that such effects can generate a desirable--for the FEL interaction--radial variation of the particle's energy in the beam, and calculate the induced energy spread in the limit of weak field.

Stupakov, G.; Huang, Z.; /SLAC

2005-12-14

403

Iron beam acceleration using direct plasma injection schemea)  

NASA Astrophysics Data System (ADS)

A new set of vanes of radio frequency quadrupole (RFQ) accelerator was commissioned using highly charged iron beam. To supply high intensity heavy ion beams to the RFQ, direct plasma injection scheme (DPIS) with a confinement solenoid was adopted. One of the difficulties to utilize the combination of DPIS and a solenoid field is a complexity of electro magnetic field at the beam extraction region, since biasing high static electric field for ion extraction, RFQ focusing field, and the solenoid magnetic field fill the same space simultaneously. To mitigate the complexity, a newly designed magnetic field clamps were used. The intense iron beam was observed with bunched structure and the total accelerated current reached 2.5 nC.

Okamura, M.; Kanesue, T.; Yamamoto, T.; Fuwa, Y.

2014-02-01

404

Polymeric flocculants processing by accelerated electron beams and microwave heating  

NASA Astrophysics Data System (ADS)

Results obtained by accelerated electron beam, microwave and simultaneous microwave and electron beam application in the chemistry of acrylamide and acrylic acid copolymers (polymeric flocculants used for wastewater treatment) are presented. Comparative results concerning the molecular weight and Huggins' constant for the acrylamide and acrylic acid copolymers obtained by classical heating, microwave heating, electron beam irradiation and simultaneous microwave and electron beam treatment are reported. Microwave heating produces high water solubility of the polymeric flocculants but median molecular weight values. Electron beam irradiation gives high molecular weight values but associated with a cross-linked structure (poor water solubility) while microwave energy addition to electron beam energy gives simultaneously high molecular weight values and high water solubility.

Martin, Diana I.; Mateescu, Elena; Craciun, Gabriela; Ighigeanu, Daniel; Ighigeanu, Adelina

2002-08-01

405

Particle Injection and Cosmic Ray Acceleration at Collisionless Parallel Shocks.  

National Technical Information Service (NTIS)

The structure of collisionless parallel shocks is studied using one-dimensional hybrid simulations, with emphasis on particle injection into the first-order Fermi acceleration process. It is argued that for sufficiently high Mach number shocks, and in the...

K. B. Quest

1987-01-01

406

Seventy Five Years of Particle Accelerators (LBNL Summer Lecture Series)  

ScienceCinema

Summer Lecture Series 2006: Andy Sessler, Berkeley Lab director from 1973 to 1980, sheds light on the Lab's nearly eight-decade history of inventing and refining particle accelerators, which continue to illuminate the nature of the universe.

Sessler, Andy

2011-04-28

407

Polarization of fast particle beams by collisional pumping  

DOEpatents

The invention relates to method and apparatus for polarizing a fast beam of particles by collisional pumping, including generating a fast beam of particles, and generating a thick electron-spin-polarized medium positioned as a target for said beam, said medium being sufficiently thick to allow said beam to interact with said medium to produce collisional pumping whereby said particle beam becomes highly polarized.

Stearns, J.W.; Kaplan, S.N.; Pyle, R.V.; Anderson, L.W.; Schlachter, A.S.; Ruby, L.

1984-10-19

408

A gas cluster ion beam accelerator  

Microsoft Academic Search

An assembled CO2 gas cluster ion beam system was assessed using a retarding field analyzer and a time-of-flight mass spectrometer. The CO2 gas was expanded to form gas clusters at the input pressure of 1–5 bar through a quartz Laval nozzle. At 4 bar, it is confirmed that the clusters consisted of about 500 molecules. Also the dependence of the

Jae-Hoon Song; Duck-Kyun Choi; Won-Kook Choi

2001-01-01

409

Acceleration of energetic charged particles: Shocks, reconnection or turbulence?  

NASA Astrophysics Data System (ADS)

Acceleration of energetic charged charged particles, most-often with power-law energy spectra occurs everywhere is space where particle-particle collision mean free paths are significantly larger than their gyro-radii. Shocks, reconnection events and turbulence have variously been proposed as acceleration mechanisms, and each must currently be considered a viable mechanism. Shocks have the advantage that they produce naturally power-law spectra in the observed range which are not very sensitive to the parameters. They are usually also fast accelerators. I first discuss the constraints which observations place on the acceleration mechanisms and show that there are both temporal and spatial constraints. Stochastic acceleration tends to be slow, so the rate of acceleration is important. In the inner heliosphere, this rate must exceed the rate of adiabatic cooling ~ 2Vw/r, where Vw is the radial solar-wind velocity. Acceleration of anomalous cosmic rays (ACR) in the heliosheath must occur on a time scale of on year to avoid producing too many multiply charged ACR. It is shown that here, stochastic acceleration has difficulties in the inner heliosheath. Reconnection events are essentially incompressible, so the divergence of the flow velocity is nearly zero, and the Parker equation would give little acceleration. Acceleration at reconnection therefore must go beyond the Parker equation - either by invoking large pitch-angle anisotropies or by extending the equation to higher order in the flow speed relative to the particle speed. An approach to using an extension of Parker's equation is discussed. Diffusive shock acceleration at the heliospheric termination shock is also discussed. It is suggested that inclusion of upstream turbulence and shock geometry provides reasonable solutions to the perceived problems with this mechanism. Finally, observation evidence is presented which suggests, strongly, that the acceleration of the ACR occurs in the inner heliosphere, not far from the heliospheric termination shock.

Jokipii, J. R.

2012-05-01

410

An MCNP-based model of a linear accelerator x-ray beam  

NASA Astrophysics Data System (ADS)

The Monte Carlo N-Particle radiation transport computer code (MCNP) has been employed on a personal computer to develop a simple model simulating the major components within the beam path of a linear accelerator radiation head, namely the electron target, primary conical collimator, beam flattening filter, wedge filter and the secondary collimators. The model was initially used to calculate the energy spectra and angular distributions of the x-ray beam for the Philips SL 75/5 linear accelerator, in a plane immediately beneath the flattening filter. These data were subsequently used as a `source' of x-rays at the target position, to assess the emergent beam from the secondary collimators. The depth dose distributions and dose profiles at constant depth for various field sizes have been calculated for a nominal operating potential of 4 MV and found to be within acceptable limits. It is concluded that the technique may be used to calculate the energy spectra of any linear accelerator upon specification of the component dimensions, materials and nominal accelerating potential. It is anticipated that this work will serve as the basis of a quality control tool for linear accelerators and treatment planning systems.

Lewis, R. D.; Ryde, S. J. S.; Hancock, D. A.; Evans, C. J.

1999-05-01

411

Heavy ion beam acceleration in the KEK digital accelerator: Induction acceleration from 200 keV to a few tens of MeV  

NASA Astrophysics Data System (ADS)

The procedure for induction acceleration of a heavy ion beam of A/Q=4 in the KEK digital accelerator is reported. This paper discusses essential issues associated with induction acceleration of ion beams from low energies, including injection error, relatively large closed orbit distortion, and a fully predictive control method for the acceleration.

Yoshimoto, T.; Barata, M.; Iwashita, T.; Harada, S.; Arakawa, D.; Arai, T.; Liu, X.; Adachi, T.; Asao, H.; Kadokura, E.; Kawakubo, T.; Kubo, T.; Leo, K. W.; Nakanishi, H.; Okada, Y.; Okamura, K.; Okazaki, K.; Someya, H.; Takayama, K.; Wake, M.

2014-01-01

412

Particle acceleration at shock fronts in AGNs and jets  

Microsoft Academic Search

Several aspects of the theory of first order Fermi acceleration at shock fronts are discussed which may be relevant for active galactic nuclei (AGNs) and jets. In the test particle picture, recent work on acceleration at oblique shocks is reviewed which indicates that such shocks produce a harder spectrum than parallel shocks. They also tend to accumulate a substantial excess

John G. Kirk

413

Planetary spin period acceleration of particles in the Jovian magnetosphere  

Microsoft Academic Search

We describe a model for the acceleration of energetic protons and relativistic electrons in the Jovian magnetosphere, employing a four-step process in which ionospheric particles are (1) accelerated outward along field lines by the centrifugal force of corotation, (2) energized by magnetic field annihilation in the Jovian magnetospheric tail, (3) convected inward from the tail, thus experiencing adiabatic compression, and

J. F. Carbary; T. W. Hill; A. J. Dessler

1976-01-01

414

The phase of particle acceleration in the flare development  

Microsoft Academic Search

Evidence is given that the particle acceleration in flares is confined to the initial phase of the flare development preceding the Ha flare maximum and lasting for less than 10 min. The impulsive acceleration process is confined to a relatively small limited volume of about 5 × 1027 cm3 in the region of highest magnetic gradient in the flare, and

Z. Švestka

1970-01-01

415

Acceleration and Trapping of Particles by Radiation Pressure  

Microsoft Academic Search

Micron-sized particles have been accelerated and trapped in stable optical potential wells using only the force of radiation pressure from a continuous laser. It is hypothesized that similar accelerations and trapping are possible with atoms and molecules using laser light tuned to specific optical transitions. The implications for isotope separation and other applications of physical interest are discussed.

A. Ashkin

1970-01-01

416

Fully vectorial accelerating diffraction-free Helmholtz beams.  

PubMed

We show that new families of diffraction-free nonparaxial accelerating optical beams can be generated by considering the symmetries of the underlying vectorial Helmholtz equation. Both two-dimensional transverse electric and magnetic accelerating wave fronts are possible, capable of moving along elliptic trajectories. Experimental results corroborate these predictions when these waves are launched from either the major or minor axis of the ellipse. In addition, three-dimensional spherical nondiffracting field configurations are presented along with their evolution dynamics. Finally, fully vectorial self-similar accelerating optical wave solutions are obtained via oblate-prolate spheroidal wave functions. In all occasions, these effects are illustrated via pertinent examples. PMID:23215489

Aleahmad, Parinaz; Miri, Mohammad-Ali; Mills, Matthew S; Kaminer, Ido; Segev, Mordechai; Christodoulides, Demetrios N

2012-11-16

417

Beam centroid and envelope model for the SLIA accelerator  

NASA Astrophysics Data System (ADS)

The RAM computer code has been developed to model the Spiral Line Induction Accelerator (SLIA), which is under development at Pulse Sciences Inc. (PSI). The code advances the beam centroid and envelope equations for a complete current pulse in this high-current recirculating accelerator. Since the beam cross-section is elliptical, in general, and the transverse x-y motions are coupled via an axial magnetic field, the beam envelope is modeled using a 4 × 4 covariance matrix. The envelope equation includes a correction for beam diamagnetism. Toroidal self-field contributions to the bending field and the transverse frequencies have been calculated; the results retain terms which were inconsistently omitted in previous derivations, leading to incorrect frequencies. The code uses a circuit model to compute the beam-loading effect on the accelerating voltage at each gap. The transverse gap forces, which drive the beam breakup (BBU) instability are also computed. Realistic field maps for all beamline elements (solenoids, stellarator coils, bending fields, and matching quadrupoles) are incorporated.

Hughes, Thomas P.; Genoni, Thomas C.

1996-05-01

418

Optical trapping and rotation of airborne absorbing particles with a single focused laser beam  

NASA Astrophysics Data System (ADS)

We measure the periodic circular motion of single absorbing aerosol particles that are optically trapped with a single focused Gaussian beam and rotate around the laser propagation direction. The scattered light from the trapped particle is observed to be directional and change periodically at 0.4-20 kHz. The instantaneous positions of the moving particle within a rotation period are measured by a high-speed imaging technique using a charge coupled device camera and a repetitively pulsed light-emitting diode illumination. The centripetal acceleration of the trapped particle as high as ˜20 times the gravitational acceleration is observed and is attributed to the photophoretic forces.

Lin, Jinda; Li, Yong-qing

2014-03-01

419

1 ms Pulse Beam Generation and Acceleration by Photocathode Radio Frequency Gun and Superconducting Accelerator  

NASA Astrophysics Data System (ADS)

We report the successful generation and acceleration of a 1-ms-long pulse and multibunch electron beam by a normal conducting photocathode RF gun and a super conducting accelerator at the KEK Superconducting Test Facility (STF). A 1.3 GHz normal conducting RF gun generates a 1 ms and 10 mA macropulse that fully satisfies the designed parameters. This is the longest macropulse generated by a normal conducting RF gun with a frequency of more than 1 GHz. A beam acceleration of up to 40 MeV was demonstrated with more than 60% of the designed average current. The accelerated beam properties were evaluated: the intensity and energy fluctuations were 3.8% and less than 0.08%, respectively. These beam properties are sufficient for the requirement of the STF operation including that in the quantum beam project, which is high-brightness-X-ray generation by inverse laser Compton scattering. The intensity fluctuation should be improved toward the International Linear Collider (ILC) for uniform acceleration.

Kuriki, Masao; Iijima, Hokuto; Hosoda, Seiichi; Watanabe, Ken; Hayano, Hitoshi; Urakawa, Junji; Isoyama, Goro; Kato, Ryukou; Kawase, Keigo; Kuramoto, Ayaka; Kashiwagi, Shigeru; Sakaue, Kazuyuki

2013-05-01

420

Optimization and beam control in large-emittance accelerators: Neutrino factories;  

SciTech Connect

Schemes for intense sources of high-energy muons require collection, rf capture, and transport of particle beams with unprecedented emittances, both longitudinally and transversely. These large emittances must be reduced or ''cooled'' both in size and in energy spread before the muons can be efficiently accelerated. Therefore, formation of muon beams sufficiently intense to drive a Neutrino Factory or Muon Collider requires multi-stage preparation. Further, because of the large beam phase space which must be successfully controlled, accelerated, and transported, the major stages that comprise such a facility: proton driver, production, capture, phase rotation, cooling, acceleration, and storage are complex and strongly interlinked. Each of the stages must be consecutively matched and simultaneously optimized with upstream and downstream systems, meeting challenges not only technically in the optics and component design, but also in the modeling of both new and extended components. One design for transverse cooling, for example, employs meter-diameter solenoids to maintain strong focusing--300-500 mr beam divergences--across ultra-large momentum ranges, {ge} {+-}20% {delta}p/p, defying conventional approximations to the dynamics and field representation. To now, the interplay of the different systems and staging strategies has not been formally addressed. This work discusses two basic, but different approaches to a Neutrino Factory and how the staging strategy depends on beam parameters and method of acceleration.

Carol Johnstone

2004-08-23

421

Accelerators for the PS neutrino beam  

NASA Astrophysics Data System (ADS)

A recent memorandum for an experimental proposal [1] was discussed during the CERN PS and SPS experimental committee (SPSC) of April 2011 and at the Research Board of June 2011. The proposed experiment, with objective to investigate the anomalous ?? ? ?e oscillations, aims at re-using the discontinued CERN PS Neutrino Facility (PSNF) and experimental zones to install a 150 ton liquid argon time projection chamber (LArTPC) as near detector and a 600 ton LArTPC as far detector. This article will summarize the experimental needs, the proposed facility layout, a primary beam production scheme and the requirements for the reconstruction of the PSNF.

Steerenberg, R.; Calviani, M.; Gschwendtner, E.; Pardons, A.; Vincke, H.

2013-02-01

422

Removing 20 nm Particles Using a Supersonic Argon Particle Beam Generated with a Contoured Laval Nozzle  

Microsoft Academic Search

A cryogenic particle beam is an effective means of removing nano-sized contaminant particles, but the particle beam generated with a simple-hole nozzle has not been successful in removing particles smaller than 30 nm. Based on molecular dynamics (MD) simulation results that smaller cryogenic particles moving at a higher velocity are more effective in removing contaminant particles in the 10 nm

Jin Won Lee; Kwang-Seok Hwang; Ki-Hyun Lee; Min-Young Yi; Mi-Jeong Lee

2009-01-01

423

Physics design of linear accelerators for intense ion beams  

SciTech Connect

Advances in the physics and technology of linear accelerators for intense ion beams are leading to new methods for the design of such machines. The physical effects that limit beam current and brightness are better understood and provide the criteria for choosing the rf frequency and for determining optimum focusing configurations to control longitudinal and transverse emittances. During the past decade, the use of developments such as the radio-frequency quadrupole, multiple beams, funneling, ramped-field linac tanks, and self-matching linac tanks is leading to greater design flexibility and improved performance capabilities. 39 refs., 3 tabs., 1 fig.

Wangler, T.P.

1988-01-01

424

Recent progress of laser driven particle acceleration at Peking University  

NASA Astrophysics Data System (ADS)

Recently, radiation pressure acceleration (RPA) has been proposed and extensively studied, which shows that circularly polarized (CP) laser pulses can accelerate mono-energetic ion bunches in a phase-stable-acceleration (PSA) way from ultrathin foils. It is found that self-organizing proton beam can be stably accelerated to GeV in the interaction of a CP laser with a planar target at 1022 W/cm2. A project called Compact LAser Plasma proton Accelerator (CLAPA) is approved by MOST in China recently. A prototype of laser driven proton accelerator (1 to 15 MeV/1 Hz) based on the PSA mechanism and plasma lens is going to be built at Peking University in the next five years. It will be upgraded to 200 MeV later for applications such as cancer therapy, plasma imaging and fast ignition for inertial confine fusion.

Yan, Xue-Qing; Lin, Chen; Lu, Hai-Yang; Zhu, Kun; Zou, Yu-Bin; Wang, Hong-Yong; Liu, Bing; Zhao, Shuan; Zhu, Jiao; Geng, Yi-Xing; Fu, He-Zheng; Shang, Yong; Cao, Chao; Shou, Yin-Ren; Song, Wei; Lu, Yuan-Rong; Yuan, Zhong-Xi; Guo, Zhi-Yu; He, Xian-Tu; Chen, Jia-Er

2013-10-01

425

Laser-Driven Proton Beams: Acceleration Mechanism, Beam Optimization, and Radiographic Applications  

Microsoft Academic Search

This paper reviews recent experimental activity in the area of optimization, control, and application of laser-accelerated proton beams, carried out at the Rutherford Appleton Laboratory and the Laboratoire pour lpsilaUtilisation des Lasers Intenses 100 TW facility in France. In particular, experiments have investigated the role of the scale length at the rear of the plasma in reducing target-normal-sheath-acceleration acceleration efficiency.

Marco Borghesi; Carlo Alberto Cecchetti; Toma Toncian; Julien Fuchs; Lorenzo Romagnani; Satyabrata Kar; P. A. Wilson; Patrizio Antici; Patrick Audebert; Erik Brambrink; Ariane Pipahl; Munib Amin; Ralph Jung; Jens Osterholz; Oswald Willi; Wigen Nazarov; Robert J. Clarke; Margaret Notley; David Neely; Patrick Mora; Thomas Grismayer; Guy Schurtz; Angelo Schiavi; Yasuhiko Sentoku

2008-01-01

426

Electron acceleration to energies beyond GeV by a relativistic ion beam instability.  

PubMed

Synchrotron emission suggests the presence of TeV electrons at various astrophysical objects. We propose a mechanism for the acceleration of electrons to ultrahigh energies (UHE) by intense electrostatic waves (ESWs). The latter are driven by dense proton beams that move at relativistic speeds relative to a background plasma and the electrons are accelerated by their nonlinear interaction with the ESWs. We follow the evolution of the wave instability by means of particle-in-cell (PIC) simulations. After the instability has saturated, we obtain spatially confined electron voids in which secondary instabilities develop due to resonant interactions between the beams and the background protons, generating intense ESWs which accelerate electrons to ultrarelativistic speeds within times of a few hundred inverse plasma frequencies. PMID:15524640

Dieckmann, M E; Eliasson, B; Shukla, P K

2004-09-01

427

Stable laser-driven proton beam acceleration from a two-ion-species ultrathin foil.  

PubMed

By using multidimensional particle-in-cell simulations, we present a new regime of stable proton beam acceleration which takes place when a two-ion-species shaped foil is illuminated by a circularly polarized laser pulse. In the simulations, the lighter protons are nearly instantaneously separated from the heavier carbon ions due to the charge-to-mass ratio difference. The heavy ion layer expands in space and acts to buffer the proton layer from the Rayleigh-Taylor-like (RT) instability that would have otherwise degraded the proton beam acceleration. A simple three-interface model is formulated to explain qualitatively the stable acceleration of the light ions. In the absence of the RT instability, the high quality monoenergetic proton bunch persists even after the laser-foil interaction ends. PMID:20867984

Yu, Tong-Pu; Pukhov, Alexander; Shvets, Gennady; Chen, Min

2010-08-01

428

Advanced methods for the computation of particle beam transport and the computation of electromagnetic fields and beam-cavity interactions  

SciTech Connect

The University of Maryland Dynamical Systems and Accelerator Theory Group carries out research in two broad areas: the computation of charged particle beam transport using Lie algebraic methods and advanced methods for the computation of electromagnetic fields and beam-cavity interactions. Important improvements in the state of the art are believed to be possible in both of these areas. In addition, applications of these methods are made to problems of current interest in accelerator physics including the theoretical performance of present and proposed high energy machines. The Lie algebraic method of computing and analyzing beam transport handles both linear and nonlinear beam elements. Tests show this method to be superior to the earlier matrix or numerical integration methods. It has wide application to many areas including accelerator physics, intense particle beams, ion microprobes, high resolution electron microscopy, and light optics. With regard to the area of electromagnetic fields and beam cavity interactions, work is carried out on the theory of beam breakup in single pulses. Work is also done on the analysis of the high behavior of longitudinal and transverse coupling impendances, including the examination of methods which may be used to measure these impedances. Finally, work is performed on the electromagnetic analysis of coupled cavities and on the coupling of cavities to waveguides.

Dragt, A.J.; Gluckstern, R.L.

1990-11-01

429

Injector and beam transport simulation study of proton dielectric wall accelerator  

NASA Astrophysics Data System (ADS)

A simulation study of a short-pulsed proton injector for, and beam transport in, a dielectric wall accelerator (DWA) has been carried out using the particle-in-cell (PIC) code Warp. It was shown that applying "tilt pulse" voltage waveforms on three electrodes enables the production of a shorter bunch by the injector. The fields in the DWA beam tube were simulated using Computer Simulation Technology's Microwave Studio (CST MWS) package, with various choices for the boundary conditions. For acceleration in the DWA, the beam transport was simulated with Warp, using applied fields obtained by running CST MWS. Our simulations showed that the electric field at the entrance to the DWA represents a challenging issue for the beam transport. We thus simulated a configuration with a mesh at the entrance of the DWA, intended to improve the entrance field. In these latter simulations, a proton bunch was successfully accelerated from 130 keV to about 36 MeV in a DWA with a length of 36.75 cm. As the beam bunch progresses, its transverse dimensions diminish from (roughly) 0.5×0.5 cm to 0.2×0.4 cm. The beam pulse lengthens from 1 cm to 2 cm due to lack of longitudinal compression fields.

Zhao, Quantang; Yuan, P.; Zhang, Z. M.; Cao, S. C.; Shen, X. K.; Jing, Y.; Ma, Y. Y.; Yu, C. S.; Li, Z. P.; Liu, M.; Xiao, R. Q.; Zhao, H. W.

2012-12-01

430

Coronal shock energetic particle acceleration in self-generated turbulence: Expectations for Solar Orbiter  

NASA Astrophysics Data System (ADS)

Understanding the acceleration processes of solar energetic particles (SEPs) in large solar eruptions is complicated by observational difficulties. The large distance of the observing spacecraft from the eruption site allows the particles to scatter off the interplanetary magnetic field turbulence, hence causing severe uncertainties to the temporal profile of the acceleration. The spacecraft's relative motion to the solar surface results in difficulties in making a distinction between temporal and local spatial effects in the observed particle event evolution. With the forthcoming Solar Orbiter mission, these uncertainties are diminished, as the spacecraft will observe the Sun much closer, and during one phase of the orbit will co-rotate with the Sun. In this work, we study how shock-accelerated SEPs would be observed by Solar Orbiter. We will study the effect of self-generated waves to the acceleration process and the subsequently observed SEP intensities at 0.225 Rs, using a self-consistent Monte Carlo simulation code, in which the particle-scattering plasma waves are generated by the particle beams time-dependently. We will report how the observed particle fluxes and their energies depend on the initial injection efficiency and the shock velocity, and how these parameters influence the temporal evolution of the observed particle event.

Laitinen, Timo

431

Acceleration of beam ions during major radius compression in TFTR  

SciTech Connect

Tangentially co-injected deuterium beam ions were accelerated from 82 keV up to 150 keV during a major radius compression experiment in TFTR. The ion energy spectra and the variation in fusion yield were in good agreement with Fokker-Planck code simulations. In addition, the plasma rotation velocity was observed to rise during compression.

Wong, K.L.; Bitter, M.; Hammett, G.W.; Heidbrink, W.; Hendel, H.; Kaita, R.; Scott, S.; Strachan, J.D.; Tait, G.; Bell, M.G.

1985-09-01

432

Calculations of beam dynamics in Sandia linear electron accelerators, 1984  

Microsoft Academic Search

A number of code and analytic studies were made during 1984 which pertain to the Sandia linear accelerators MABE and RADLAC. The important results of the calculations are summarized. New results include a better understanding of gap induced radial oscillations, leakage currents in a typical MABE gas, emittance growth in a beam passing through a series of gaps, some new

J. W. Poukey; P. D. Coleman

1985-01-01

433

Accelerator Rings with Polarized Beams and Spin Manipulation  

Microsoft Academic Search

The basic formulas of describing polarization dynamics in accelerators will be presented. These include the equation of spin motion in a comoving coordinate frame for spin vectors, spin transport matrices, spin transport quaternions, and spinors. It will also be shown how spin flelds evolve in these four ways of descibing spin motion. Furthermore, some basic concepts of polarized beams in

Georg H. Hofistaetter

434

Reactive accelerated cluster erosion (RACE) by ionized cluster beams  

NASA Astrophysics Data System (ADS)

Beams of ionized clusters accelerated up to about 120 keV kinetic energy per cluster are used for cluster impact lithography. Chemical reactions of clusters of CO 2, or of SF 6, respectively, are found to assist the physical erosion by hypervelocity cluster impacts in yielding volatile products. Natural diamond, silicon and Pyrex glass have been microstructured showing very smooth eroded surfaces.

Gspann, Jürgen

1996-05-01

435

Laser acceleration and nonlinear beam dynamics. Final technical report.  

National Technical Information Service (NTIS)

This research contract covers the period April 1990, September 1991. The work to be done under the contract was theoretical research in the areas of nonlinear beam dynamics and laser acceleration. In this final report we will discuss the motivation for th...

C. Pellegrini

1991-01-01

436

Observation of laser multiple filamentation process and multiple electron beams acceleration in a laser wakefield accelerator  

SciTech Connect

The multiple filaments formation process in the laser wakefield accelerator (LWFA) was observed by imaging the transmitted laser beam after propagating in the plasma of different density. During propagation, the laser first self-focused into a single filament. After that, it began to defocus with energy spreading in the transverse direction. Two filaments then formed from it and began to propagate independently, moving away from each other. We have also demonstrated that the laser multiple filamentation would lead to the multiple electron beams acceleration in the LWFA via ionization-induced injection scheme. Besides, its influences on the accelerated electron beams were also analyzed both in the single-stage LWFA and cascaded LWFA.

Li, Wentao; Liu, Jiansheng; Wang, Wentao; Chen, Qiang; Zhang, Hui; Tian, Ye; Zhang, Zhijun; Qi, Rong; Wang, Cheng; Leng, Yuxin; Li, Ruxin; Xu, Zhizhan [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai 201800 (China)] [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai 201800 (China)

2013-11-15

437

An improved 8 GeV beam transport system for the Fermi National Accelerator Laboratory  

SciTech Connect

A new 8 GeV beam transport system between the Booster and Main Ring synchrotrons at the Fermi National Accelerator Laboratory is presented. The system was developed in an effort to improve the transverse phase space area occupied by the proton beam upon injection into the Main Ring accelerator. Problems with the original system are described and general methods of beamline design are formulated. Errors in the transverse properties of a beamline at the injection point of the second synchrotron and their effects on the region in transverse phase space occupied by a beam of particles are discussed. Results from the commissioning phase of the project are presented as well as measurements of the degree of phase space dilution generated by the transfer of 8 GeV protons from the Booster synchrotron to the Main Ring synchrotron.

Syphers, M.J.

1987-06-01

438

Controlling the betatron oscillations of a wakefield-accelerated electron beam by temporally asymmetric laser pulses  

NASA Astrophysics Data System (ADS)

Based on two-dimensional particle-in-cell simulations, we investigated the electron beam's transverse oscillations by temporally asymmetric laser pulses in laser wakefield acceleration. Of particular interest in this article are the effects of ultrashort laser pulses having sharp rising and slow falling time scales. In this situation, the accelerated electron beam interacts directly with the laser field and undergoes transverse oscillations due to a phase-slip with the laser field. This oscillation can be matched with the betatron oscillation due to the focusing force of the ions, which can lead to a large transverse oscillation amplitude due to the resonance between them. Furthermore, in this case, the electron beam can be microbunched at the laser wavelength, which may provide the possibility for generation of a coherent synchrotron radiation.

Nam, Inhyuk; Hur, Min Sup; Uhm, Han Sup; Hafz, Nasr A. M.; Suk, Hyyong

2011-04-01

439

Controlling the betatron oscillations of a wakefield-accelerated electron beam by temporally asymmetric laser pulses  

SciTech Connect

Based on two-dimensional particle-in-cell simulations, we investigated the electron beam's transverse oscillations by temporally asymmetric laser pulses in laser wakefield acceleration. Of particular interest in this article are the effects of ultrashort laser pulses having sharp rising and slow falling time scales. In this situation, the accelerated electron beam interacts directly with the laser field and undergoes transverse oscillations due to a phase-slip with the laser field. This oscillation can be matched with the betatron oscillation due to the focusing force of the ions, which can lead to a large transverse oscillation amplitude due to the resonance between them. Furthermore, in this case, the electron beam can be microbunched at the laser wavelength,