FEL2011 - List of Authors (Ruan, J.)

Paper	Title	Page
MOPC12	Coherent Synchrotron Radiation and Bunch Compression Studies in the Emittance Exchange Beamline at the Fermilab A0 Photoinjector	121
	J.C.T. Thangaraj, M.D. Church, H.T. Edwards, A.S. Johnson, A.H. Lumpkin, J. Ruan, J.K. Santucci, Y.-E. Sun, R.M. Thurman-Keup Fermilab, Batavia, USA T.J. Maxwell, P. Piot Northern Illinois University, DeKalb, Illinois, USA
	One of goals of the Fermilab A0 photoinjector is to investigate experimentally the transverse to longitudinal emittance exchange principle. Coherent synchrotron radiation in the emittance exchange line could limit short pulse operation of the emittance exchanger. In this paper, we present experimental and simulation study of the coherent synchroton radiation (CSR) in the emittance exchange line at A0 photoinjector. We also show how EEX can be used to compress a bunch by adding chirp to the incoming beam.

THOA3	Demonstration of Transverse-to-longitudinal Emittance Exchange at A0 Photoinjector	443
	J. Ruan, A.S. Johnson, A.H. Lumpkin, Y.-E. Sun, R.M. Thurman-Keup Fermilab, Batavia, USA
	The 3-D phase-space manipulation of electron beams enhances the performance of next generation accelerators including high energy colliders and accelerator based light sources. In this paper we will report an observation of near ideal transverse to longitudinal emittance exchange at the Fermilab A0 Photoinjector. The emittance exchange (EEX) beamline consists a 3.9 GHz normal conducting deflecting mode cavity positioned between two magnetic doglegs. We will also compare the experiment results to simulations.

THPA21	Commissioning of a Streak Camera for Laser Characterization at NML	515
	J. Ruan, A.H. Lumpkin Fermilab, Batavia, USA T.J. Maxwell Northern Illinois University, DeKalb, Illinois, USA
	A streak camera will be used for longitudinal profile measurement of a drive laser for the superconducting radio frequency photoinjector test facility at Fermilab. We are evaluating both a Photek intensified CCD camera and a Hamamatsu cooled CCD camera as the readout camera option for the Hamamatsu C5680 streak camera unit with a synchroscan sweep unit. Trade on low signal sensitivity and spatial resolution for the two lens-coupled options are being evaluated. In addition, an ultrashort laser pulse from a Ti:sapphire laser is used to measure the temporal resolution for both configurations.

THPB19	Investigations of OTR Polarization Effects in Beam-profile Monitors	594
	A.H. Lumpkin, A.S. Johnson, J. Ruan, R.M. Thurman-Keup Fermilab, Batavia, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. The characterization of transverse beam size using optical transition radiation (OTR) imaging is a well-established technique at many accelerators including the Fermilab A0 photoinjector (A0PI) facility. However, there is growing empirical evidence that the utilization of the polarization component orthogonal to the dimension of interest results in a smaller observed projected image profile. We have continued investigations of this phenomenon with a more controlled experiment where the linear polarizers are selectable in a filter wheel which also included a blank glass position to compensate for the optical path. The aperture for light collection is thus kept fixed compared to our previous tests. We also have balanced the digital camera gain to present similar signal levels to the data analysis program for both the total OTR and the polarized components. At the relatively low Lorentz factor (gamma) of 30, we observed 10-15% projected profile size reductions on a 65-micron beam size case with the perpendicularly polarized components. This anomalous effect in magnitude is compared to results from a standard OTR point-spread-function model.

THPB24	Generation and Acceleration of Uniformly-filled Ellipsoidal Bunches Obtained via Space-charge Expansion from a Semiconductor Photocathode	605
	P. Piot, J. Ruan, Y.-E. Sun, J.C.T. Thangaraj Fermilab, Batavia, USA T.J. Maxwell Northern Illinois University, DeKalb, Illinois, USA
	We report on the experimental generation, acceleration and characterization of a uniformly-filled electron bunch obtained via space-charge-driven expansion (so called "blow-out regime") at the A0 photoinjector at Fermilab. The beam is photoemitted from a CsTe photocathode using a short (<~200 fs) ultraviolet pulse obtained via frequency-tripling of an amplified Ti:Sp infrared pulse. The produced electron bunches are characterized with conventional diagnostics and the measurements are bench-marked against numerical simulations performed with ASTRA and GPT.

Paper

Title

Page

Coherent Synchrotron Radiation and Bunch Compression Studies in the Emittance Exchange Beamline at the Fermilab A0 Photoinjector

121

J.C.T. Thangaraj, M.D. Church, H.T. Edwards, A.S. Johnson, A.H. Lumpkin, J. Ruan, J.K. Santucci, Y.-E. Sun, R.M. Thurman-Keup
Fermilab, Batavia, USA
T.J. Maxwell, P. Piot
Northern Illinois University, DeKalb, Illinois, USA

One of goals of the Fermilab A0 photoinjector is to investigate experimentally the transverse to longitudinal emittance exchange principle. Coherent synchrotron radiation in the emittance exchange line could limit short pulse operation of the emittance exchanger. In this paper, we present experimental and simulation study of the coherent synchroton radiation (CSR) in the emittance exchange line at A0 photoinjector. We also show how EEX can be used to compress a bunch by adding chirp to the incoming beam.

THOA3

Demonstration of Transverse-to-longitudinal Emittance Exchange at A0 Photoinjector

443

J. Ruan, A.S. Johnson, A.H. Lumpkin, Y.-E. Sun, R.M. Thurman-Keup
Fermilab, Batavia, USA

The 3-D phase-space manipulation of electron beams enhances the performance of next generation accelerators including high energy colliders and accelerator based light sources. In this paper we will report an observation of near ideal transverse to longitudinal emittance exchange at the Fermilab A0 Photoinjector. The emittance exchange (EEX) beamline consists a 3.9 GHz normal conducting deflecting mode cavity positioned between two magnetic doglegs. We will also compare the experiment results to simulations.

THPA21

Commissioning of a Streak Camera for Laser Characterization at NML

515

J. Ruan, A.H. Lumpkin
Fermilab, Batavia, USA
T.J. Maxwell
Northern Illinois University, DeKalb, Illinois, USA

A streak camera will be used for longitudinal profile measurement of a drive laser for the superconducting radio frequency photoinjector test facility at Fermilab. We are evaluating both a Photek intensified CCD camera and a Hamamatsu cooled CCD camera as the readout camera option for the Hamamatsu C5680 streak camera unit with a synchroscan sweep unit. Trade on low signal sensitivity and spatial resolution for the two lens-coupled options are being evaluated. In addition, an ultrashort laser pulse from a Ti:sapphire laser is used to measure the temporal resolution for both configurations.

THPB19

Investigations of OTR Polarization Effects in Beam-profile Monitors

594

A.H. Lumpkin, A.S. Johnson, J. Ruan, R.M. Thurman-Keup
Fermilab, Batavia, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The characterization of transverse beam size using optical transition radiation (OTR) imaging is a well-established technique at many accelerators including the Fermilab A0 photoinjector (A0PI) facility. However, there is growing empirical evidence that the utilization of the polarization component orthogonal to the dimension of interest results in a smaller observed projected image profile. We have continued investigations of this phenomenon with a more controlled experiment where the linear polarizers are selectable in a filter wheel which also included a blank glass position to compensate for the optical path. The aperture for light collection is thus kept fixed compared to our previous tests. We also have balanced the digital camera gain to present similar signal levels to the data analysis program for both the total OTR and the polarized components. At the relatively low Lorentz factor (gamma) of 30, we observed 10-15% projected profile size reductions on a 65-micron beam size case with the perpendicularly polarized components. This anomalous effect in magnitude is compared to results from a standard OTR point-spread-function model.

THPB24

Generation and Acceleration of Uniformly-filled Ellipsoidal Bunches Obtained via Space-charge Expansion from a Semiconductor Photocathode

605

P. Piot, J. Ruan, Y.-E. Sun, J.C.T. Thangaraj
Fermilab, Batavia, USA
T.J. Maxwell
Northern Illinois University, DeKalb, Illinois, USA

We report on the experimental generation, acceleration and characterization of a uniformly-filled electron bunch obtained via space-charge-driven expansion (so called "blow-out regime") at the A0 photoinjector at Fermilab. The beam is photoemitted from a CsTe photocathode using a short (<~200 fs) ultraviolet pulse obtained via frequency-tripling of an amplified Ti:Sp infrared pulse. The produced electron bunches are characterized with conventional diagnostics and the measurements are bench-marked against numerical simulations performed with ASTRA and GPT.