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Title: A Phase Matching, Adiabatic Accelerator

Abstract

Tabletop accelerators are a thing of the future. Reducing their size will require scaling down electromagnetic wavelengths; however, without correspondingly high field gradients, particles will be more susceptible to phase-slippage – especially at low energy. We investigate how an adiabatically-tapered dielectric-lined waveguide could maintain phase-matching between the accelerating mode and electron bunch. We benchmark our simple model with CST and implement it into ASTRA; finally we provide a first glimpse into the beam dynamics in a phase-matching accelerator.

Authors:
 [1];  [2];  [3]; ORCiD logo [4]
  1. Hamburg U.
  2. DESY
  3. CFEL, Hamburg
  4. Northern Illinois U.
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1423253
Report Number(s):
FERMILAB-CONF-17-584-APC
1627155
DOE Contract Number:
AC02-07CH11359
Resource Type:
Conference
Resource Relation:
Conference: 8th International Particle Accelerator Conference, Copenhagen, Denmark, 05/14-05/19/2017
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS

Citation Formats

Lemery, Francois, Flöttmann, Klaus, Kärtner, Franz, and Piot, Philippe. A Phase Matching, Adiabatic Accelerator. United States: N. p., 2017. Web. doi:10.18429/JACoW-IPAC2017-WEPAB123.
Lemery, Francois, Flöttmann, Klaus, Kärtner, Franz, & Piot, Philippe. A Phase Matching, Adiabatic Accelerator. United States. doi:10.18429/JACoW-IPAC2017-WEPAB123.
Lemery, Francois, Flöttmann, Klaus, Kärtner, Franz, and Piot, Philippe. Mon . "A Phase Matching, Adiabatic Accelerator". United States. doi:10.18429/JACoW-IPAC2017-WEPAB123. https://www.osti.gov/servlets/purl/1423253.
@article{osti_1423253,
title = {A Phase Matching, Adiabatic Accelerator},
author = {Lemery, Francois and Flöttmann, Klaus and Kärtner, Franz and Piot, Philippe},
abstractNote = {Tabletop accelerators are a thing of the future. Reducing their size will require scaling down electromagnetic wavelengths; however, without correspondingly high field gradients, particles will be more susceptible to phase-slippage – especially at low energy. We investigate how an adiabatically-tapered dielectric-lined waveguide could maintain phase-matching between the accelerating mode and electron bunch. We benchmark our simple model with CST and implement it into ASTRA; finally we provide a first glimpse into the beam dynamics in a phase-matching accelerator.},
doi = {10.18429/JACoW-IPAC2017-WEPAB123},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon May 01 00:00:00 EDT 2017},
month = {Mon May 01 00:00:00 EDT 2017}
}

Conference:
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  • An adiabatically tapered solenoidal magnetic field is used to match positron beam source emittance to accelerating section acceptance. Such a matching system improves the accepted energy band which has been accurately computed and compared with analytical determination. The tapered field is provided by stacked pancakes and solenoids of various radii; total lens length is about 0.75m. The adiabatic matching system took the place of a quarter wave transformer system and has been in operation for two years. Positron conversion ratio is 3.3% for a 1 GeV incident electron beam and presents a factor of nearly two of improvement for themore » positron yield. Energy bandwidth of positron beam has also been increased by a factor of nearly 2.5; the output positron beam energy is of 1.2 GeV.« less
  • We present a general concept to accelerate non-relativistic charged particles. Our concept employs an adiabatically-tapered dielectric-lined waveguide which supports accelerating phase velocities for synchronous acceleration. We propose an ansatz for the transient field equations, show it satisfies Maxwell's equations under an adiabatic approximation and find excellent agreement with a finite-difference time-domain computer simulation. The fields were implemented into the particle-tracking program {\sc astra} and we present beam dynamics results for an accelerating field with a 1-mm-wavelength and peak electric field of 100~MV/m. The numerical simulations indicate that amore » $$\sim 200$$-keV electron beam can be accelerated to an energy of $$\sim10$$~MeV over $$\sim 10$$~cm. The novel scheme is also found to form electron beams with parameters of interest to a wide range of applications including, e.g., future advanced accelerators, and ultra-fast electron diffraction.« less
  • Typical designs for a Heavy Ion Fusion Power Plant require the source injector to deliver 100 beams, packed into an array with a spacing of 7 cm. When designing source injectors using a single large aperture source for each beam, the emitter surfaces are packed into an array with a spacing of 30 cm. Thus, the matching section of the source injector must not only prepare the beam for transport in a FODO lattice, but also funnel the beams together. This can be accomplished by an ESQ matching section in which each beam travels on average at a slight anglemore » to the axis of the quadrupoles and uses the focusing effect of the FODO lattice to maintain the angle. At the end of the matching section, doublet steering is used to bring the beams parallel to each other for injection into the main accelerator. A specific solution of this type for an 84-beam source injector is presented. PACS: 41.75.Ak,41.85.Ar, 41.85.Ja« less
  • Typical designs for a Heavy Ion Fusion Power Plant require the source injector to deliver 100 beams, packed into an array with a spacing of 7 cm. When designing source injectors using a single large aperture source for each beam, the emitter surfaces are packed into an array with a spacing of 30 cm. Thus, the matching section of the source injector must not only prepare the beam for transport in a FODO lattice, but also funnel the beams together. This can be accomplished by an ESQ matching section in which each beam travels on average at a slight anglemore » to the axis of the quadrupoles and uses the focusing effect of the FODO lattice to maintain the angle. At the end of the matching section, doublet steering is used to bring the beams parallel to each other for injection into the main accelerator. A specific solution of this type for an 84-beam source injector is presented.« less