2011 Particle Accelerator Conference - List of Authors (Stratakis, D.)

Paper

Title

Page

Standing Wakefield Accelerator Based on Periodic Dielectric Structures

124

X. Wei, G. Andonian, J.B. Rosenzweig, D. Stratakis
UCLA, Los Angeles, California, USA

In recent years dielectric wakefield accelerators (DWA) have attracted significant attention for applications in high energy physics and THz radiation sources. However, one needs sufficiently short driving bunches in order to take advantage of the DWA's scaling characteristics to achieve high gradient and high frequency accelerating fields. Since a single large charge Q driving bunch is difficult to be compressed to the needed rms bunch length, a driving bunch train with smaller Q and small emittance, should be used instead for the DWA. In view of this senario, the group velocity of the excited wakefields needs to be decreased to nearly zero, so the electromagnetic energy does not vacate the structure during the bunch train. In this paper we propose a standing wakefield accelerator based on periodic dielectric structures, and address the difference between the proposed structure and the conventional DWA.

MOP056

A Compact and High Performance Muon Capture Channel for Muon Accelerators

208

D. Stratakis
UCLA, Los Angeles, California, USA
J.C. Gallardo, R. B. Palmer
BNL, Upton, Long Island, New York, USA

Funding: Work is funded by U.S. Dept. of Energy grant numbers DE AC02-98CH10886.
It is widely believed that a neutrino factory would deliver unparallel performance in studying neutrino mixing and would provide tremendous sensitivity to new physics in the neutrino sector. Here we will describe and simulate the front-end of the neutrino factory system, which plays critical role in determining the number of muons that can be accepted by the downstream accelerators. In this system, a proton bunch on a target creates secondaries that drift into a capture transport channel. A sequence of rf cavities forms the resulting muon beams into strings of bunches of differing energies, aligns the bunches to nearly equal central energies, and initiates ionization cooling. For this, the muon beams are transported through sections containing high-gradient cavities and strong focusing solenoids. In this paper we present results of optimization and variation studies toward obtaining the maximum number of muons for a neutrino factory by using a compact transport channel.
Stratakis et al. Phys. Rev. ST Accel. Beams 14, 011001 (2011).

MOP057

A SLAB Dielectric Structure as a Source of Wakefield Acceleration and THz Cherenkov Radiation Generation

211

D. Stratakis, G. Andonian, J.B. Rosenzweig, X. Wei
UCLA, Los Angeles, USA

Funding: Work is funded by US Dept. of Energy grant numbers DE-FG03-92ER40693.
Acceleration of electrons in wakefields set up by a series of drive bunches in a dielectric structure has been proposed as a possible component of next-generation accelerators. Here, we discuss future experimental work with a slab sub-millimeter dielectric loaded accelerator structure that in contrast to conventional dielectric tubes should diminish the effects of transverse wakes and will permit higher total charge to be accelerated. The proposed experiment will allow the generation of unprecedented peak power at THz frequencies. In addition, it can generate ~50-150 MV/m drive fields and thus will allow the testing of acceleration using witness and drive beams. We examine details of the geometry and composition of the structures to be used in the experiment.

THOAS4

Enhancement of RF Breakdown Threshold of Microwave Cavities by Magnetic Insulation

2053

D. Stratakis
UCLA, Los Angeles, California, USA
J.C. Gallardo, R. B. Palmer
BNL, Upton, Long Island, New York, USA

Funding: This work is funded by US Dept. of Energy grant number DE AC02-98CH10886.
Limitations on the maximum achievable accelerating gradient of microwave cavities can influence the performance, length, and cost of particle accelerators. Gradient limitations are widely believed to be initiated by electron emission from the cavity surfaces. Here, we show that field emission is effectively suppressed by applying a tangential magnetic field to the cavity walls, so higher gradients can be achieved. Numerical simulations indicate that the magnetic field prevents electrons leaving these surfaces and subsequently picking up energy from the electric field. Implementation of the proposed concept into prospective particle accelerator applications is studied by two specific examples - a multi TeV lepton-antilepton collider and a linear muon accelerator driver for an intense neutrino source.

Slides THOAS4 [1.441 MB]

Paper	Title	Page
MOP011	Standing Wakefield Accelerator Based on Periodic Dielectric Structures	124
	X. Wei, G. Andonian, J.B. Rosenzweig, D. Stratakis UCLA, Los Angeles, California, USA
	In recent years dielectric wakefield accelerators (DWA) have attracted significant attention for applications in high energy physics and THz radiation sources. However, one needs sufficiently short driving bunches in order to take advantage of the DWA's scaling characteristics to achieve high gradient and high frequency accelerating fields. Since a single large charge Q driving bunch is difficult to be compressed to the needed rms bunch length, a driving bunch train with smaller Q and small emittance, should be used instead for the DWA. In view of this senario, the group velocity of the excited wakefields needs to be decreased to nearly zero, so the electromagnetic energy does not vacate the structure during the bunch train. In this paper we propose a standing wakefield accelerator based on periodic dielectric structures, and address the difference between the proposed structure and the conventional DWA.

MOP056	A Compact and High Performance Muon Capture Channel for Muon Accelerators	208
	D. Stratakis UCLA, Los Angeles, California, USA J.C. Gallardo, R. B. Palmer BNL, Upton, Long Island, New York, USA
	Funding: Work is funded by U.S. Dept. of Energy grant numbers DE AC02-98CH10886. It is widely believed that a neutrino factory would deliver unparallel performance in studying neutrino mixing and would provide tremendous sensitivity to new physics in the neutrino sector. Here we will describe and simulate the front-end of the neutrino factory system, which plays critical role in determining the number of muons that can be accepted by the downstream accelerators. In this system, a proton bunch on a target creates secondaries that drift into a capture transport channel. A sequence of rf cavities forms the resulting muon beams into strings of bunches of differing energies, aligns the bunches to nearly equal central energies, and initiates ionization cooling. For this, the muon beams are transported through sections containing high-gradient cavities and strong focusing solenoids. In this paper we present results of optimization and variation studies toward obtaining the maximum number of muons for a neutrino factory by using a compact transport channel. Stratakis et al. Phys. Rev. ST Accel. Beams 14, 011001 (2011).

MOP057	A SLAB Dielectric Structure as a Source of Wakefield Acceleration and THz Cherenkov Radiation Generation	211
	D. Stratakis, G. Andonian, J.B. Rosenzweig, X. Wei UCLA, Los Angeles, USA
	Funding: Work is funded by US Dept. of Energy grant numbers DE-FG03-92ER40693. Acceleration of electrons in wakefields set up by a series of drive bunches in a dielectric structure has been proposed as a possible component of next-generation accelerators. Here, we discuss future experimental work with a slab sub-millimeter dielectric loaded accelerator structure that in contrast to conventional dielectric tubes should diminish the effects of transverse wakes and will permit higher total charge to be accelerated. The proposed experiment will allow the generation of unprecedented peak power at THz frequencies. In addition, it can generate ~50-150 MV/m drive fields and thus will allow the testing of acceleration using witness and drive beams. We examine details of the geometry and composition of the structures to be used in the experiment.

THOAS4	Enhancement of RF Breakdown Threshold of Microwave Cavities by Magnetic Insulation	2053
	D. Stratakis UCLA, Los Angeles, California, USA J.C. Gallardo, R. B. Palmer BNL, Upton, Long Island, New York, USA
	Funding: This work is funded by US Dept. of Energy grant number DE AC02-98CH10886. Limitations on the maximum achievable accelerating gradient of microwave cavities can influence the performance, length, and cost of particle accelerators. Gradient limitations are widely believed to be initiated by electron emission from the cavity surfaces. Here, we show that field emission is effectively suppressed by applying a tangential magnetic field to the cavity walls, so higher gradients can be achieved. Numerical simulations indicate that the magnetic field prevents electrons leaving these surfaces and subsequently picking up energy from the electric field. Implementation of the proposed concept into prospective particle accelerator applications is studied by two specific examples - a multi TeV lepton-antilepton collider and a linear muon accelerator driver for an intense neutrino source.
	Slides THOAS4 [1.441 MB]