pbpl - authors: show

J. S. Jacob

First Name: J

Middle Name: S

Last Name: Jacob

Full Name: J. S. Jacob

tags:

Potential Duplicate Authors:

3 papers

title: Adjustable, short focal length permanent-magnet quadrupole based electron beam final focus system

format: journal article

year: 2005

9 authors: J. K. Lim | P. Frigola | G. Travish | J. B. Rosenzweig | S. Anderson | W. J. Brown | J.S. Jacob | C.L. Robbins | A.M. Tremaine

abstract: Advanced high-brightness beam applicaitons such as inverse-Compton scattering (ICS) depend on achieving of ultra-small spot sizes in high current beams. Modern injectors and compressors enable the production of high-brightness beams having needed short bunch lengths and small emittances. Along with these beam properties comes the need to produce tighter foci, using stronger, shorter focal length optics. An approach to creating such strong focusing-systems using high field, small-bore permanent-magnet quadrupoles (PMQs) is reported here. A final focus system employing three PMQs, each composed of 16 neodymium iron boride sectors in a Halbach geometry has been installed in the PLEIADES ICS experiment. The field gradient in these PMQs is 560 T/m, the highest ever reported in a magnetic optics system. As the magnets are of a fixed field-strength, the focusing system is tuned by adjusting the position of the three magnets along the beamline axis, in analogy to familiar camera optics. This paper discusses the details of the focusing system, simulation, design, fabrication and experimental procedure in creating ultra-small beams at PLEIADES.

keywords:

Download | View | Details | edit | delete

title: Velocity bunching of high-brightness electron beams

format: journal article

year: 2005

11 authors: S. Anderson | P. Musumeci | J. B. Rosenzweig | W. J. Brown | R. J. England | M. Ferrario | J. S. Jacob | M.C. Thompson | G. Travish | A. M. Tremaine | R. Yoder

abstract: Velocity bunching has been recently proposed as a tool for compressing electron beam pulses in modernhigh brightness photoinjector sources. This tool is familiar from earlier schemes implemented for bunching dc electron sources, but presents peculiar challenges when applied to high current, low emittance beams from photoinjectors. The main difficulty foreseen is control of emittance oscillations in the beam in this scheme, which can be naturally considered as an extension of the emittance compensation process at moderate energies. This paper presents two scenarios in which velocity bunching, combined with emittance control, is to play a role in nascent projects. The first is termed ballistic bunching, where the changing of relative particle velocities and positions occur in distinct regions, a short high gradient linac, and a drift length. This scenario is discussed in the context of the proposed ORION photoinjector. Simulations are used to explore the relationship between the degree of bunching, and the emittance compensation process. Experimental measurements performed at the UCLA Neptune Laboratory of the surprisingly robust bunching process, as well as accompanying deleterious transverse effects, are presented. An unanticipated mechanism for emittance growth in bends for highly momentum chirped beam was identified and studied in these experiments. The second scenario may be designated as phase space rotation, and corresponds closely to the recent proposal of Ferrario and Serafini. Its implementation for the compression of the electron beam pulse length in the PLEIADES inverse Compton scattering (ICS) experiment at LLNL is discussed. It is shown in simulations that optimum compression may be obtained by manipulation of the phases in low gradient traveling wave accelerator sections. Measurements of the bunching and emittance control achieved in such an implementation at PLEIADES, as well as aspects of the use of velocity-bunched beam directly in ICS experiments, are presented.

keywords:

Download | View | Details | edit | delete

title: Ultra-High Density Electron Beams for Beam Radiation and Beam Plasma Interaction

format: conference procceeding

conference: 2005 Particle Accelerator Conference

year:

11 authors: G. Anderson | W.J. Brown | D.J. Gibson | F.V. Hartemann | J.S. Jacob | A.M. Tremaine | J.K. Lim | P. Frigola | P. Musumeci | J.B. Rosenzweig | G. Travish

abstract: Current and future applications of high brightness electron beams, which include advanced accelerators such as the plasma wake-field accelerator (PWFA) and beam radiation interactions such as inverse-Compton scattering (ICS), require both transverse and longitudinal beam sizes on the order of tens of microns. Ultra-high density beams may be produced at moderate energy (50 MeV) by compression and subsequent strong focusing of low emittance, photoinjector sources. We describe the implementation of this method used at the PLEIADES ICS x-ray source in which the photoinjector-generated beam has been compressed to 300 fsec duration using the velocity bunching technique and focused to 20 um rms size using an extremely high gradient, permanent magnet quadrupole (PMQ) focusing system.

keywords: pbpl

Download | View | Details | edit | delete

title:	Adjustable, short focal length permanent-magnet quadrupole based electron beam final focus system
format:	journal article
year:	2005
9 authors:	J. K. Lim \| P. Frigola \| G. Travish \| J. B. Rosenzweig \| S. Anderson \| W. J. Brown \| J.S. Jacob \| C.L. Robbins \| A.M. Tremaine
abstract:	Advanced high-brightness beam applicaitons such as inverse-Compton scattering (ICS) depend on achieving of ultra-small spot sizes in high current beams. Modern injectors and compressors enable the production of high-brightness beams having needed short bunch lengths and small emittances. Along with these beam properties comes the need to produce tighter foci, using stronger, shorter focal length optics. An approach to creating such strong focusing-systems using high field, small-bore permanent-magnet quadrupoles (PMQs) is reported here. A final focus system employing three PMQs, each composed of 16 neodymium iron boride sectors in a Halbach geometry has been installed in the PLEIADES ICS experiment. The field gradient in these PMQs is 560 T/m, the highest ever reported in a magnetic optics system. As the magnets are of a fixed field-strength, the focusing system is tuned by adjusting the position of the three magnets along the beamline axis, in analogy to familiar camera optics. This paper discusses the details of the focusing system, simulation, design, fabrication and experimental procedure in creating ultra-small beams at PLEIADES.
keywords:
Download \| View \| Details \| edit \| delete

title:	Velocity bunching of high-brightness electron beams
format:	journal article
year:	2005
11 authors:	S. Anderson \| P. Musumeci \| J. B. Rosenzweig \| W. J. Brown \| R. J. England \| M. Ferrario \| J. S. Jacob \| M.C. Thompson \| G. Travish \| A. M. Tremaine \| R. Yoder
abstract:	Velocity bunching has been recently proposed as a tool for compressing electron beam pulses in modernhigh brightness photoinjector sources. This tool is familiar from earlier schemes implemented for bunching dc electron sources, but presents peculiar challenges when applied to high current, low emittance beams from photoinjectors. The main difficulty foreseen is control of emittance oscillations in the beam in this scheme, which can be naturally considered as an extension of the emittance compensation process at moderate energies. This paper presents two scenarios in which velocity bunching, combined with emittance control, is to play a role in nascent projects. The first is termed ballistic bunching, where the changing of relative particle velocities and positions occur in distinct regions, a short high gradient linac, and a drift length. This scenario is discussed in the context of the proposed ORION photoinjector. Simulations are used to explore the relationship between the degree of bunching, and the emittance compensation process. Experimental measurements performed at the UCLA Neptune Laboratory of the surprisingly robust bunching process, as well as accompanying deleterious transverse effects, are presented. An unanticipated mechanism for emittance growth in bends for highly momentum chirped beam was identified and studied in these experiments. The second scenario may be designated as phase space rotation, and corresponds closely to the recent proposal of Ferrario and Serafini. Its implementation for the compression of the electron beam pulse length in the PLEIADES inverse Compton scattering (ICS) experiment at LLNL is discussed. It is shown in simulations that optimum compression may be obtained by manipulation of the phases in low gradient traveling wave accelerator sections. Measurements of the bunching and emittance control achieved in such an implementation at PLEIADES, as well as aspects of the use of velocity-bunched beam directly in ICS experiments, are presented.
keywords:
Download \| View \| Details \| edit \| delete

title:	Ultra-High Density Electron Beams for Beam Radiation and Beam Plasma Interaction
format:	conference procceeding
conference:	2005 Particle Accelerator Conference
year:
11 authors:	G. Anderson \| W.J. Brown \| D.J. Gibson \| F.V. Hartemann \| J.S. Jacob \| A.M. Tremaine \| J.K. Lim \| P. Frigola \| P. Musumeci \| J.B. Rosenzweig \| G. Travish
abstract:	Current and future applications of high brightness electron beams, which include advanced accelerators such as the plasma wake-field accelerator (PWFA) and beam radiation interactions such as inverse-Compton scattering (ICS), require both transverse and longitudinal beam sizes on the order of tens of microns. Ultra-high density beams may be produced at moderate energy (50 MeV) by compression and subsequent strong focusing of low emittance, photoinjector sources. We describe the implementation of this method used at the PLEIADES ICS x-ray source in which the photoinjector-generated beam has been compressed to 300 fsec duration using the velocity bunching technique and focused to 20 um rms size using an extremely high gradient, permanent magnet quadrupole (PMQ) focusing system.
keywords:	pbpl
Download \| View \| Details \| edit \| delete

Browse