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in creator/contributor: "Laslett, L. J."

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Effect of focusing field nonlinearities in MBE-4 on transverse beam dynamics

A particle simulation code was used to study the effect on transverse beam dynamics of nonlinearities of the focusing field in a linear accelerator transporting a multiple beam array. Nonlinear field strengths for various multiple-beam design geometries were calculated by relaxation codes for use in the simulation calculation. Nonlinearities due to asymmetry of the electrode array with respect to a single beam were found to be negligible. Electrode end effect nonlinearities led to emittance gro… more

Date: May 1, 1985

Creator: Celata, C. M.; Brady, V. O.; Laslett, L. J.; Smith, L. & Haber, I.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Preliminary design of a 10 MV ion accelerator

At the low energy end of an induction linac HIF driver the beam current is limited by our ability to control space charge by a focusing system. As a consequence, HIF induction accelerator designs feature simultaneous acceleration of many beams in parallel within a single accelerator structure. As the speed of the beams increase, the focusing system changes from electrostatic to magnetic quadrupoles with a corresponding increase in the maximum allowable current. At that point the beams are merge… more

Date: June 1, 1986

Creator: Fessenden, T. J.; Celata, C. M.; Faltens, A.; Henderson, T.; Judd, D. L.; Keefe, D. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Coherent Electromagnetic Effects in High-Current Particle Accelerators: [Part] 3. Electromagnetic-Coupling Instabilities in a Coasting Beam

The electromagnetic interaction of an intense relativistic coasting beam with itself, including the effect of a confining nonperfect vacuum tank, or a quiescent rf cavity, is investigated theoretically. It is shown that the resonances that may occur between harmonics of the particle circulation frequencies and the electromagnetic modes of the cavities can lead to a longitudinal instability of the beam. A criterion for stability of the beam against such longitudinal bunching is obtained as a res… more

Date: August 4, 1960

Creator: Laslett, L. J.; Neil, V. Kelvin & Sessler, A. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Experiments on Forming Intense Rings of Electrons Suitable for the Acceleration of Ions

Electrons were injected from a 3.3-MeV 300-A accelerator into a circular orbit in a pulsed magnetic field. Trapped ring currents of 150 A (4 x 10{sup 12} electrons) were magnetically compressed from 19 cm to 3.5 cm radii and simultaneously accelerated from 3.3 MeV to 18 MeV in energy. The rms dimensions of the cross section of the ring after compression were a = 2.3 {+-} 0.2 mm radially and b = 1.6 {+-} 0.2 mm axially. The lifetime of the ring was typically 5.5 msec, and was determined by the d… more

Date: December 16, 1968

Creator: Keefe, D.; Lambertson, G. R.; Laslett, L. J.; Perkins, W. A.; Peterson, J. M.; Sessler, A. M. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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The Electron-Ring Accelerator Program at Berkeley

Early in 1968 a research group was set up at the Lawrence Radiation Laboratory to investigate the exciting new concept of accelerating ions by means of relativistic electron rings, which had been introduced and developed by Veksler, Sarantsev, and other workers at Dubna. The initial work of our group was reported at the first USSR National Conference on Particle Accelerators in 1968. In this report the author review the subsequent progress and the present program.

Date: October 1, 1970

Creator: Peterson, J. M.; Chupp, W. W.; Garren, A. A.; Keefe, D.; Lambertson, G. R.; Laslett, L. J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Experiments on Forming,Compressing and Extracting Electron Rings for the Collective Acceleration of Ions

In experiments related to the development of the electron-ring accelerator, electrons were injected into a pulsed magnetic field to form rings that were then compressed radially to a small size. The injected beam had a current of about 150 A at an energy of 3.3 MeV with an energy spread of {+-} 0.1% and a pulse length duration of 20 nsec. At low intensity, an increase in the minor radius of the ring and a large loss of electrons was observed to occur during the compression cycle. At high intens… more

Date: October 1, 1970

Creator: Keefe, D.; Chupp, W. W.; Garren, A. A.; Lambertson, G. R.; Laslett, L. J.; Luccio, A. U. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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The Electron-Ring Accelerator Program at Lrl

A progress report is presented on the activities at LRL in connection with electron-ring accelerators. A two-stage compressor unit (employing only low-intensity beams) has been built, and operated with a 4-MeV 100-mA linac as an injector. Electron rings have been formed and compressed from 20 cm radius to 7 cm radius. A three-stage compression unit has been constructed and is now under test with the high intensity (200 A) 3.3-MeV beam of the Astron injector. The apparatus is described. Design w… more

Date: October 1, 1968

Creator: Allison Jr., R. W.; Avery, R. T.; Baker, W. R.; Chupp, W. W.; Hartwig, E. C.; Hernandez, H. P. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Transverse Two-Stream Instability in the Presence of Strong Species-Species and Image Forces

The theory of coherent transverse oscillations of two particle species is extended to include strong species-species and image forces. It is shown that in general the species-species force can considerably alter the instability threshold. Conversely, it is shown that the limit on the performance of an electron ring accelerator imposed by the requirement of stable ion electron oscillations, is not significantly improved by the inclusion of images.

Date: September 1972

Creator: Laslett, L. J.; Sessler, A. M. & Mohl, D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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On the Performance Characteristics of Electron Ring Accelerators

On the basis of our present understanding of the physical phenomena involved in an electron ring accelerator (ERA), a theoretical study is made of the performance which might be expected for an ERA. Rigorous upper bounds are obtained on the rate of energy gain, from which it is shown that, in order to prevent azimuthal instability, parameters must be selected such that (for reasonable fields, injector properties, etc., but with no safety factors) the proton energy gain is less than 80 MeV/m. Nu… more

Date: September 1, 1972

Creator: Mohl, D.; Laslett, L. J. & Sessler, A. M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Head-to-tail velocity tilt in an ion induction linac

In the earleir stages of acceleration in a heavy-ion-induction linac, acceleration and bunching rates are constrained by the allowable value of head-to-tail velocity tilt at a given location. If focusing parameters at a given location are fixed, the velocity tilt should be less than a certain upper bound to avoid too much envelope variation and consequent beam losses. For space charge dominated beams, we found some favorable particle distributions in longitudinal phase space for which the maxim… more

Date: June 1, 1986

Creator: Kim, C. H.; Judd, D. L.; Laslett, L. J.; Smith, L. & Warwick, A. I.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Preliminary results from MBE-4: a four beam induction linac for heavy ion fusion research

Preliminary results are presented from a scaled experimental multiple beam induction linac. This experiment is part of a program of accelerator research for heavy ion fusion. It is shown that multiple beams can be accelerated without significant mutual interaction. Measurements of the longitudinal dynamics of a current-amplifying induction linac are presented and compared to calculations. Coupling of transverse and longitudinal dynamics is discussed.

Date: May 1, 1986

Creator: Fessenden, T. J.; Judd, D. L.; Keefe, D.; Kim, C.; Laslett, L. J.; Smith, L. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Effect of induced charge at boundaries on transverse dynamics of a space-charge-dominated beam

A particle simulation code has been used to study the effect of transverse beam dynamics of charge induced on focusing electrodes. A linear transport system was assumed. The initial particle distribution was taken to be that of a uniform elliptical beam with a Gaussian velocity distribution. For misaligned, highly space-charge-dominated beams (betatron phase advance per lattice period less than or equal to 10/sup 0/), a large oscillation of the rms emittance occurred in a beat pattern. Lineariz… more

Date: May 1, 1985

Creator: Celata, C. M.; Haber, I.; Laslett, L. J.; Smith, L. & Tiefenback, M. G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Field quality of the end sections of SSC (Superconducting Super Collider) dipoles

The central or two-dimensional field of a dipole magnet can be calculated with some precision. The fields at the end of the magnet, which are three-dimensional in nature, provide a more complicated problem. Starting with an end design that produced a relatively good end in terms of multipole components, a method of extending parts of the straight section was used to reduce the most important harmonics, the sextupole and decapole, to a negligible level. In addition, the effect of extending an ir… more

Date: September 1, 1986

Creator: Hassenzahl, W. V.; Caspi, S.; Gilbert, W.; Helm, M.; Laslett, L. J. & Morgan, G. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Development of heavy ion induction linear accelerators as drivers for inertial confinement fusion

There is a continuing study in the USA of the feasibility of an induction linac fusion driver, which would accelerate multiple heavy-ion beams through a sequence of pulsed transformers and amplify the beam current during acceleration. The driver cost could be $200/Joule or less and the cost of electricity in the range of .050-.055$/kWhr. As a next stage of development to assess the feasibility of this approach we propose an ''Induction Linac Systems Experiment''. This will test some of the tech… more

Date: June 1, 1988

Creator: Warwick, A. I.; Celata, C.; Faltens, A.; Fessenden, T. J.; Judd, D. L.; Keffe, D. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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The ``inverse problem`` to the evaluation of magnetic fields

In the design of superconducting magnet elements, such as may be required to guide and focus ions in a particle accelerator, one frequently premises some particular current distribution and then proceeds to compute the consequent magnetic field through use of the laws of Biot and Savart or of Ampere. When working in this manner one of course may need to revise frequently the postulated current distribution before arriving at a resulting magnetic field of acceptable field quality. It therefore i… more

Date: December 4, 1992

Creator: Caspi, S.; Helm, M.; Laslett, L. J. & Brady, V.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Evolution of the amplitude distribution function for a beam subjected to stochastic cooling

The suggestion of S. van der Meer for stochastic cooling or feedback damping of a circulating charged particle beam offers promise of increasing the luminosity of a storage ring and may be a particularly attractive technique if antiprotons are to be employed as one of the beams in such a device. The original report of van der Meer considered the repeated use of a kicker to suppress the transverse phase-space displacement of the centroid of a group of particles detected at a pick-up station situ… more

Date: May 1, 1977

Creator: Laslett, L. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Development of a 40 mm bore magnet cross section with high field uniformity for the 6. 6T SSC dipole

The SSC requires a very uniform dipole field. A 40 mm bore diameter winding cross section has been developed which has computed multipole coefficients less than 1 x 10/sup -6/ of the dipole field at 10 mm radius for an operating field of 6.6T at 4.35 K. This cross section has 4 conductor blocks (3 wedges, 16 turns) per quadrant in the inner layer, and two blocks (1 wedge, 20 turns) in the outer layer. ''Partially keystoned'' cable is used; the inner cable has 23 strands of .0318 inch diameter w… more

Date: September 1, 1986

Creator: Caspi, S.; Gilbert, W.; Helm, M.; Laslett, L. J. & Taylor, C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Transport of intense ion beams

The possibility of using intense bursts of heavy ions to initiate an inertially confined fusion reaction has stimulated interest in the transport of intense unneutralized heavy ion beams by quadrupole or solenoid systems. This problem was examined in some detail, using numerical integration of the coupled envelope equations for the quadrupole case. The general relations which emerge are used to develop examples of high energy transport systems and as a basis for discussing the limitations impos… more

Date: March 16, 1977

Creator: Lambertson, G.; Laslett, L. J. & Smith, L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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An approach to 3D magnetic field calculation using numerical and differential algebra methods

Motivated by the need for new means for specification and determination of 3D fields that are produced by electromagnetic lens elements in the region interior to coil windings and seeking to obtain techniques that will be convenient for accurate conductor placement and dynamical study of particle motion, we have conveniently gene the representation of a 2D magnetic field to 3D. We have shown that the 3 dimensioal magnetic field components of a multipole magnet in the curl-fire divergence-fire r… more

Date: July 17, 1992

Creator: Caspi, S.; Helm, M.; Laslett, L. J. & Brady, V. O.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Progress Report in Physics for the Period July 1, 1950, to December 31, 1950

No Description Available.

Date: March 15, 1951

Creator: Fox, G. W.; Caldwell, W. C.; Carlson, J. F.; Danielson, G. C.; Jensen, E. N.; Knipp, J. K. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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The effects of filament magnetization in superconducting magnets as calculated by POISSON

Magnetization of superconducting material can be introduced into POISSON through a field dependent permeability table (in the same way that iron characteristics are introduced). This can be done by representing measured magnetization data of the increasing and decreasing field by two independent B-..gamma.. curves (..gamma.. = 1/..mu..). Magnetization curves of this type were incorporated into the current regions of the program POISSON and their effect on the field coefficients observed. We hav… more

Date: September 1, 1986

Creator: Caspi, S.; Gilbert, W. S.; Helm, M. & Laslett, L. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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The use of harmonics in 3-D magnetic fields

Motivated by the need for new means for specification and determination of 3-D fields that are produced by electromagnetic lens elements in the region interior to coil windings and seeking to obtain techniques that will be convenient for accurate conductor placement and dynamical study of particle motion, the authors have generalized the representation of a 2-D magnetic field to 3-D. They have shown that the 3-D magnetic field components of a multipole magnet in the curl-free divergence-free re… more

Date: September 1, 1993

Creator: Caspi, S.; Helm, M. & Laslett, L. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Simulation studies of space-charge-dominated beam transport in large aperture ratio quadrupoles

For many cases of interest in the design of heavy-ion fusion accelerators, the maximum transportable current in a magnetic quadrupole lattice scales as ({alpha}/L){sup 2} where {alpha} is the useful dynamic aperture and L is the half-lattice period. There are many cost benefits to maximizing the usable aperture which must be balanced against unwanted effects such as possible emittance growth and particle loss from anharmonic fringe fields. We have used two independent simulation codes to model … more

Date: May 1, 1993

Creator: Fawley, W. M.; Laslett, L. J.; Celata, C. M.; Faltens, A. & Haber, I.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Synthesis of MBE-4 accelerating waveforms

An ion induction linac for HIF must operate near the space charge current limit along most of its length. Small errors in the voltages applied to the accelerating gaps can readily produce local unwanted beam bunching and consequent beam loss. Uncompensated space charge forces will generate current loss from longitudinal beam spreading. In the design of the MBE-4 ideal acceleration voltages were developed that assure self-similar amplifying current waveforms at each position along the accelerato… more

Date: May 1, 1985

Creator: Kim, C. H.; Brady, V. O.; Fessenden, T. J.; Judd, D. L. & Laslett, L. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department