PAC2013 - List of Authors (Musumeci, P.)

Paper

Title

Page

Transverse Beam Dynamics in Plasma Guided Laser Driven Acceleration

126

D.B. Cesar, P. Musumeci
UCLA, Los Angeles, California, USA

We describe the upgrade of the UCLA Pegasus advanced photoinjector laboratory with a new terawatt laser amplifier. This will allow the investigation of a photogun as a source for direct and plasma based laser acceleration. External injection promises to take advantage of the precision and high brightness capabilities offered by state-of-the-art RF photogun technology to increase beam quality and shot-to-shot reproducibility.

MOPAC43

Results of Short Pulse Driven LLNL/UCLA IFEL Experiment

156

J.T. Moody, P. Musumeci
UCLA, Los Angeles, California, USA
G.G. Anderson, S.G. Anderson, S.M. Betts, S.E. Fisher, D.J. Gibson, A.M. Tremaine, S.S.Q. Wu
LLNL, Livermore, California, USA

Funding: This work was supported by DOE grant DE-FG02-92ER40693, Defense of Threat Reduction Agency award HDTRA1-10-1-0073 and University of California Office of the President award 09-LR-04-117055-MUSP.
The results of the LLNL/UCLA inverse free electron laser (IFEL) experiment are presented. A 500 mJ 120 fs Ti:Saph laser pulse interacts with a short electron beam in a planar undulator tapered both in magnetic field strength and period to accelerate the electron beam. The tapering of the undulator maintains resonant energy exchange between the laser and electron beam while the electron beam's energy increases. We observe an energy modulation from 77 MeV to 120 MeV. Through use of simulations that are consistent with the observed data, we report a peak acceleration gradient of at least 180 MeV/m.

TUOBB4

Measurement of Ultrasmall Transverse Spot Size

K.G. Roberts, R.K. Li, P. Musumeci
UCLA, Los Angeles, California, USA
B.T. Jacobson
RadiaBeam, Santa Monica, USA

Funding: DARPA
The imaging of extremely small, sub-5 micron, transverse beam spot sizes has been a priority in accelerator physics. Here we propose a scheme to generate and image a beam spot size about 1 micron at PEGASUS laboratory at UCLA. We are preparing a 0.8 mm, 1 pC, 10 MeV electron beam to be sent through a permanent magnet quadrupole (PMQ) triplet of strength 130 T/m, focusing the beam to a waist 1.5 microns and a total focal length of 4.5 mm. We use a YAG screen at the beam waist and a mirror to direct optical (520 nm green) light into a Schwarzschild microscope to collimate the light. We will then image the beam using a CCD camera outside of the beam line.

Slides TUOBB4 [45.484 MB]

TUPAC29

Modeling Space Charge Effects in Optical Bunchers

511

L.V. Ho, J.P. Duris, R.K. Li, P. Musumeci
UCLA, Los Angeles, California, USA

Funding: DOE grant DE-FG02-92ER40693
This paper introduces a 1-D, self-consistent simulation of Inverse Free Electron Laser (IFEL) based optical bunchers. Starting with a review of the conventional (monochromatic) IFEL bunching, we consider slow amplitude variation and multiple harmonics of the fundamental radiation wave. We model two new bunching schemes – the adiabatic and harmonic microbuncher and compare the bunching mechanisms between the optical bunchers as well as space charge effects to the modified IFEL interaction. Here, we present a model approximating the space charge fields and verification of the simulation with the well-known Free Electron Laser (FEL) simulator, Genesis 1.3.

TUPMA16

High Capture Low Energy Spread Inverse Free Electron Laser Accelerator

619

J.P. Duris, R.K. Li, P. Musumeci, E.W. Threlkeld
UCLA, Los Angeles, California, USA

Funding: This work was supported by DOE grant DE-FG02-92ER40693, Defense of Threat Reduction Agency award HDTRA1-10-1-0073, and University of California Office of the President award 09-LR-04-117055-MUSP.
We present the design and construction of a strongly period-, field-, and gap-tapered helical undulator for use in a high-gradient, high-efficiency helical IFEL experiment at Brookhaven ATF. The undulator design achieves efficient acceleration without prebunching by matching the ponderomotive and resonant energy gradients along the length of the interaction for the measured laser parameters. Simulations based on the measured undulator fields and experimental parameters suggest that as much as 43 % of a 50 MeV beam will be accelerated to 94 MeV with 2.3 % rms energy spread.

TUPSM03

10s Femtosecond Bunch Length Measurement Based on Coherent Transition Radiation

631

X.H. Lu, W.-H. Huang, C.-X. Tang
TUB, Beijing, People's Republic of China
R.K. Li, P. Musumeci, K.G. Roberts, H.L. To
UCLA, Los Angeles, California, USA

In this paper, we discuss bunch length measurement based on coherent transition radiation for 10s femtosecond electron bunches with of several MeV energy and several pC charge. The ultrashort bunch length is obtained by velocity bunching using a compact dual slot resonantly coupled linac located after an RF photoinjector. Strong focusing with a solenoid is required to enhance the radiation generation. Filters are used to reconstruct coherent transition radiation spectrum. The transverse and longitudinal form factors are also studied with simulation.

TUPSM28

Innovative Low-Energy Ultra-Fast Electron Diffraction (UED) System

697

E.W. Threlkeld, P. Musumeci
UCLA, Los Angeles, USA
S. Boucher, L. Faillace, A.V. Smirnov
RadiaBeam, Santa Monica, USA

Funding: Work supported by US DOE grant # DE-SC0006274
RadiaBeam, in collaboration with UCLA, is developing an innovative, inexpensive, low-energy ultra-fast electron diffraction (UED) system which allows us to reconstruct a single ultrafast event with a single pulse of electrons. Time resolved measurement of atomic motion is one of the frontiers of modern science, and advancements in this area will greatly improve our understanding of the basic processes in materials science, chemistry and biology. The high-frequency (GHz), high voltage, phase-locked RF field in the deflector allows temporal resolution as fine as sub-100 fs. In this paper, we show the complete design of the UED system based on this concept, including initial beam measurements.

THOAA1

Single-Shot Ultrafast Electron Microscopy

R.K. Li, P. Musumeci
UCLA, Los Angeles, California, USA

Electron microscopy is an extremely powerful tool for a variety of studies in physics, biology, material science, and industrial applications. One of the mostly desired capabilities of a future electron microscopy is the improved resolving power in the time domain approaching ps or even fs levels. In this paper we show that the low emittance, low energy spread electron beams from a state-of-the-art photoinjector can be used to take single-shot intensity-contrast snapshots of the sample. The spatial-temporal resolution can achieve 10 nm – 1 ps level. The beam optics is based on permanent quadrupole magnets which are compact and avoid the high charge density cross-over in contrast to solenoids. The proposed single-shot ultrafast electron microscopy will greatly facilitate the studies of irreversible dynamic process in materials.

Slides THOAA1 [4.613 MB]

THPAC37

Surface Plasmon Resonance Enhanced Multiphoton Emission from Metallic Cathode

1220

H.L. To, G. Andonian, R.K. Li, P. Musumeci
UCLA, Los Angeles, USA
G. Andonian
RadiaBeam, Marina del Rey, USA

We investigate the effect of surface plasmonic optical field enhancement on multiphoton emission from a metallic photocathode. In a previous experiment *, two orders of magnitude increase in charge yield was obtained using a slightly off resonance nanohole array plasmonic structure. In a new attempt, a nanohole structure will be fabricated, using focused ion beam milling, such that the resonance wavelength is at 800 nm, the central wavelength of the photoinjector driver laser pulse. The charge yield is expected to increase dramatically compared to the charge yield from previous nanostructure. We will also present optical characterization of the nanostructures as well the beam characteristics (intrinsic emittance and bunch length) from this nanostructured photocathode.
* Li et al., PRL 2013.

Paper	Title	Page
MOPAC27	Transverse Beam Dynamics in Plasma Guided Laser Driven Acceleration	126
	D.B. Cesar, P. Musumeci UCLA, Los Angeles, California, USA
	We describe the upgrade of the UCLA Pegasus advanced photoinjector laboratory with a new terawatt laser amplifier. This will allow the investigation of a photogun as a source for direct and plasma based laser acceleration. External injection promises to take advantage of the precision and high brightness capabilities offered by state-of-the-art RF photogun technology to increase beam quality and shot-to-shot reproducibility.

MOPAC43	Results of Short Pulse Driven LLNL/UCLA IFEL Experiment	156
	J.T. Moody, P. Musumeci UCLA, Los Angeles, California, USA G.G. Anderson, S.G. Anderson, S.M. Betts, S.E. Fisher, D.J. Gibson, A.M. Tremaine, S.S.Q. Wu LLNL, Livermore, California, USA
	Funding: This work was supported by DOE grant DE-FG02-92ER40693, Defense of Threat Reduction Agency award HDTRA1-10-1-0073 and University of California Office of the President award 09-LR-04-117055-MUSP. The results of the LLNL/UCLA inverse free electron laser (IFEL) experiment are presented. A 500 mJ 120 fs Ti:Saph laser pulse interacts with a short electron beam in a planar undulator tapered both in magnetic field strength and period to accelerate the electron beam. The tapering of the undulator maintains resonant energy exchange between the laser and electron beam while the electron beam's energy increases. We observe an energy modulation from 77 MeV to 120 MeV. Through use of simulations that are consistent with the observed data, we report a peak acceleration gradient of at least 180 MeV/m.

TUOBB4	Measurement of Ultrasmall Transverse Spot Size
	K.G. Roberts, R.K. Li, P. Musumeci UCLA, Los Angeles, California, USA B.T. Jacobson RadiaBeam, Santa Monica, USA
	Funding: DARPA The imaging of extremely small, sub-5 micron, transverse beam spot sizes has been a priority in accelerator physics. Here we propose a scheme to generate and image a beam spot size about 1 micron at PEGASUS laboratory at UCLA. We are preparing a 0.8 mm, 1 pC, 10 MeV electron beam to be sent through a permanent magnet quadrupole (PMQ) triplet of strength 130 T/m, focusing the beam to a waist 1.5 microns and a total focal length of 4.5 mm. We use a YAG screen at the beam waist and a mirror to direct optical (520 nm green) light into a Schwarzschild microscope to collimate the light. We will then image the beam using a CCD camera outside of the beam line.
	Slides TUOBB4 [45.484 MB]

TUPAC29	Modeling Space Charge Effects in Optical Bunchers	511
	L.V. Ho, J.P. Duris, R.K. Li, P. Musumeci UCLA, Los Angeles, California, USA
	Funding: DOE grant DE-FG02-92ER40693 This paper introduces a 1-D, self-consistent simulation of Inverse Free Electron Laser (IFEL) based optical bunchers. Starting with a review of the conventional (monochromatic) IFEL bunching, we consider slow amplitude variation and multiple harmonics of the fundamental radiation wave. We model two new bunching schemes – the adiabatic and harmonic microbuncher and compare the bunching mechanisms between the optical bunchers as well as space charge effects to the modified IFEL interaction. Here, we present a model approximating the space charge fields and verification of the simulation with the well-known Free Electron Laser (FEL) simulator, Genesis 1.3.

TUPMA16	High Capture Low Energy Spread Inverse Free Electron Laser Accelerator	619
	J.P. Duris, R.K. Li, P. Musumeci, E.W. Threlkeld UCLA, Los Angeles, California, USA
	Funding: This work was supported by DOE grant DE-FG02-92ER40693, Defense of Threat Reduction Agency award HDTRA1-10-1-0073, and University of California Office of the President award 09-LR-04-117055-MUSP. We present the design and construction of a strongly period-, field-, and gap-tapered helical undulator for use in a high-gradient, high-efficiency helical IFEL experiment at Brookhaven ATF. The undulator design achieves efficient acceleration without prebunching by matching the ponderomotive and resonant energy gradients along the length of the interaction for the measured laser parameters. Simulations based on the measured undulator fields and experimental parameters suggest that as much as 43 % of a 50 MeV beam will be accelerated to 94 MeV with 2.3 % rms energy spread.

TUPSM03	10s Femtosecond Bunch Length Measurement Based on Coherent Transition Radiation	631
	X.H. Lu, W.-H. Huang, C.-X. Tang TUB, Beijing, People's Republic of China R.K. Li, P. Musumeci, K.G. Roberts, H.L. To UCLA, Los Angeles, California, USA
	In this paper, we discuss bunch length measurement based on coherent transition radiation for 10s femtosecond electron bunches with of several MeV energy and several pC charge. The ultrashort bunch length is obtained by velocity bunching using a compact dual slot resonantly coupled linac located after an RF photoinjector. Strong focusing with a solenoid is required to enhance the radiation generation. Filters are used to reconstruct coherent transition radiation spectrum. The transverse and longitudinal form factors are also studied with simulation.

TUPSM28	Innovative Low-Energy Ultra-Fast Electron Diffraction (UED) System	697
	E.W. Threlkeld, P. Musumeci UCLA, Los Angeles, USA S. Boucher, L. Faillace, A.V. Smirnov RadiaBeam, Santa Monica, USA
	Funding: Work supported by US DOE grant # DE-SC0006274 RadiaBeam, in collaboration with UCLA, is developing an innovative, inexpensive, low-energy ultra-fast electron diffraction (UED) system which allows us to reconstruct a single ultrafast event with a single pulse of electrons. Time resolved measurement of atomic motion is one of the frontiers of modern science, and advancements in this area will greatly improve our understanding of the basic processes in materials science, chemistry and biology. The high-frequency (GHz), high voltage, phase-locked RF field in the deflector allows temporal resolution as fine as sub-100 fs. In this paper, we show the complete design of the UED system based on this concept, including initial beam measurements.

THOAA1	Single-Shot Ultrafast Electron Microscopy
	R.K. Li, P. Musumeci UCLA, Los Angeles, California, USA
	Electron microscopy is an extremely powerful tool for a variety of studies in physics, biology, material science, and industrial applications. One of the mostly desired capabilities of a future electron microscopy is the improved resolving power in the time domain approaching ps or even fs levels. In this paper we show that the low emittance, low energy spread electron beams from a state-of-the-art photoinjector can be used to take single-shot intensity-contrast snapshots of the sample. The spatial-temporal resolution can achieve 10 nm – 1 ps level. The beam optics is based on permanent quadrupole magnets which are compact and avoid the high charge density cross-over in contrast to solenoids. The proposed single-shot ultrafast electron microscopy will greatly facilitate the studies of irreversible dynamic process in materials.
	Slides THOAA1 [4.613 MB]

THPAC37	Surface Plasmon Resonance Enhanced Multiphoton Emission from Metallic Cathode	1220
	H.L. To, G. Andonian, R.K. Li, P. Musumeci UCLA, Los Angeles, USA G. Andonian RadiaBeam, Marina del Rey, USA
	We investigate the effect of surface plasmonic optical field enhancement on multiphoton emission from a metallic photocathode. In a previous experiment , two orders of magnitude increase in charge yield was obtained using a slightly off resonance nanohole array plasmonic structure. In a new attempt, a nanohole structure will be fabricated, using focused ion beam milling, such that the resonance wavelength is at 800 nm, the central wavelength of the photoinjector driver laser pulse. The charge yield is expected to increase dramatically compared to the charge yield from previous nanostructure. We will also present optical characterization of the nanostructures as well the beam characteristics (intrinsic emittance and bunch length) from this nanostructured photocathode. Li et al., PRL 2013.