| Paper | Title | Page |
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| MPPE068 | Effects on Flat-Beam Generation from Space-Charge Force and Beamline Errors | 3774 |
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| The transformation of a round, angular-momentum-dominated electron beam into a flat beam using a skew-quadrupole channel has been developed theoretically in several papers and demonstrated experimentally at the Fermilab/NICADD Photoinjector Laboratory. In this paper, we address the impacts of space-charge force and beamline errors on the round-to-flat beam transformation. We discuss the physical process of angular momentum cancellation during the beam passage through the skew-quadrupole channel, present analytical and numerical studies of the linear and nonlinear space-charge forces, and evaluate the corresponding limits on the ratio of vertical-to-horizontal emittances. We also investigate the sensitivities of flat-beam emittances on several systematic factors such as errors on quadrupole strengths and alignments. | ||
| TPAE037 | Simulation of the Laser Acceleration Experiment at the Femilab/NICADD Photoinjector Laboratory | 2503 |
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| The possibility of using a laser to accelerate electrons in a waveguide structure with dimension much larger than the laser wavelength was first proposed by Pantell [NIM A 393 pg 1-5 (1997)] and investigated analytically by M. Xie [reports LBNL-40558 (1997) and LBNL-42055 (1998) available from LBNL Berkeley]. In the present paper we present the status of our experimental plan to demonstrate the laser interaction on an electron beam with initial momentum of 40-50 MeV/c. A laser (λ=1.06 micron) operating on the TM*01 mode has been developed. The large wavenumber (k~6x106 m-1) together with the initial low electron momentum poses a serious problem for efficient acceleration. In the present paper, we present start-to-end simulations of the laser acceleration experiment as foreseen to be installed in the upgraded Femilab/NICADD photoinjector laboratory. | ||
| TPAE048 | The UCLA/FNPL Time Resolved Underdense Plasma Lens Experiment | 3013 |
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Funding: Work Supported by U.S. Dept. of Energy grant DE-FG03-92ER40693. An underdense plasma lens experiment is planned as a collaboration between UCLA and the Fermilab NICADD Photoinjector Laboratory (FNPL). The experiment will focus on measuring the variation of the plasma focusing along the longitudinal beam axis and comparing these results with theory and simulation. The experiment will utilize a thin gaussian underdense plasma lens with peak density 6 x 1012 cm-3 and a FWHM length of 1.6 cm. This plasma lens will have a focusing strength equivalent to a quadrupole magnet with a 180 T/m field gradient. A 15 MeV, 8nC electron beam with nominal dimensions sr = 400 μm and sz = 2.1 mm will be focused by this plasma lens onto an OTR screen approximately 2 cm downstream of the lens. The light from the OTR screen will be imaged into a streak camera in order to directly measure the correlation between z and sr within the beam. Status and progress on the experiment are reported. |
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| TPPE044 | Upgrade of the Fermilab/NICADD Photoinjector Laboratory | 2848 |
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Funding: This work was supported by Universities Research Association Inc. under contract DE-AC02-76CH00300 with the U.S. DOE, and by NICADD. The Femilab/NICADD photoinjector laboratory (FNPL) is a 16 MeV electron accelerator dedicated to beam dynamics and advanced accelerator studies. FNPL will soon be capable of operating at 50 MeV, after the installation of a high gradient TESLA cavity. In this paper we present the foreseen design for the upgraded facility along with its performance. We discuss the possible application of 50 MeV beam including the possible use of FNPL as an injector for the superconducting module and test facility (SM&TF). |
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| WPAP032 | Emittances Studies at the Fermilab/NICADD Photoinjector Laboratory | |
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Funding: This work was supported by the Universities Research Association Inc. under contract DE-AC02-76CH00300 with the U.S. DOE, and by NICADD. The Fermilab/NICADD photoinjector incorporates an L-band rf-gun capable of generating 1-10 nC bunches. The bunches are then accelerated to 16 MeV with a TESLA superconducting cavity. In the present paper we present parametric studies of transverse emittances and energy spread for a various operating points of the electron source (RF-gun E-field, laser length and spot size, and solenoid settings). We especially study the impact, on transverse emittance, of Gaussian and Plateau temporal distribution of the photocathode drive-laser. |
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| WPAP043 | Production of Transverse Controllable Laser Density Distribution in Fermilab/NICADD Photoinjector | 2783 |
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| The Fermilab/NICADD photoinjector laboratory consist of a photoemission electron source based on an L band rf-gun. The CsTe photocathode is illuminated by an ultrashort UV laser. The transport line from the laser to the photocathode was recently upgraded to allow imaging of an object plane located ~20 m from the photocathode. This upgrade allows the generation of transverse laser distributions with controlled nonuniformity, yielding the production of an electron beam with various transverse densities patterns. Measuring the evolution of the artificial pattern on the electron bunch provides information that can be used to benchmark numerical simulations and investigate the impact of space charge. Preliminary data on these investigations are presented in the present paper. | ||
| WPAT083 | Steering and Focusing Effects in TESLA Cavity Due to High Order Mode and Input Couplers | 4135 |
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Funding: This work was supported by Universities Research Association Inc. under contract DE-AC02-76CH00300 with the U.S. Department of Energy, and by NICADD. Many state-of-art electron accelerator proposals incorporate TESLA-type superconducting standing wave cavities. These cavities include input coupler (to feed the RF power into the cavity) and a pairs of high order mode couplers (HOM) to absorb the energy associated to HOM field excited as the bunch passes through the cavity. In the present paper we investigate, using numerical simulations, the impact of the input and HOM couplers on the beam dynamics. We show the overall effects are: a dipole kick (zeroth order) and normal and skew quadrupole-type focusing (first order). We present parametric studies of the strength of these effect for various operating gradients and incoming beam energies. We finally study the impact of this non-asymmetric field on the beam dynamics, taking as an example the low energy section of the European X-FEL injector. |
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| RPAT091 | Longitudinal Electron Bunch Diagnostics Using Coherent Transition Radiation | 4254 |
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| The longitudinal charge distribution of electron bunches in the Fermilab A0 photo-injector was determined by using the coherent transition radiation produced by electrons passing through a thin metallic foil. The auto-correlation of the transition radiation signal was measured with a Michelson type interferometer. The response function of the interferometer was determined from measured and simulated power spectra for low electron bunch charge and maximum longitudinal compression. Kramers-Kroning technique was used to determine longitudinal charge distribution. Measurements were performed for electron bunch lengths in the range from 0.3 to 2 ps (rms). |