55 research outputs found
Overestimation of thermal emittance in solenoid scans due to coupled transverse motion
The solenoid scan is a widely used method for the in-situ measurement of the
thermal emittance in a photocathode gun. The popularity of this method is due
to its simplicity and convenience since all rf photocathode guns are equipped
with an emittance compensation solenoid. This paper shows that the solenoid
scan measurement overestimates the thermal emittance in the ordinary
measurement configuration due to a weak quadrupole field (present in either the
rf gun or gun solenoid) followed by a rotation in the solenoid. This coupled
transverse dynamics aberration introduces a correlation between the beam's
horizontal and vertical motion leading to an increase in the measured 2D
transverse emittance, thus the overestimation of the thermal emittance. This
effect was systematically studied using both analytic expressions and numerical
simulations. These studies were experimentally verified using an L-band
1.6-cell rf photocathode gun with a cesium telluride cathode, which shows a
thermal emittance overestimation of 35% with a rms laser spot size of 2.7 mm.
The paper concludes by showing that the accuracy of the solenoid scan can be
improved by using a quadrupole magnet corrector, consisting of a pair of normal
and skew quadrupole magnets.Comment: 12 pages, 13 figure
Plasma Dynamics
Contains table of contents for Section 2 and reports on four research projects.Lawrence Livermore National Laboratory Subcontract 6264005National Science Foundation Grant ECS 84-13173National Science Foundation Grant ECS 85-14517U.S. Air Force - Office of Scientific Research Contract AFOSR 84-0026U.S. Army - Harry Diamond Laboratories Contract DAAL02-86-C-0050U.S. Navy - Office of Naval Research Contract N00014-87-K-2001National Science Foundation Grant ECS 85-15032National Science Foundation Grant ECS 88-22475U.S. Department of Energy Contract DE-AC02-ET-5101
Plasma Dynamics
Contains table of contents for Section 2 and reports on four research projects.National Science Foundation Grant ECS-89-02990U.S. Air Force - Office of Scientific Research Grant AFOSR 89-0082-CU.S. Army - Harry Diamond Laboratories Contract DAAL02-89-K-0084U.S. Army - Harry Diamond Laboratories Contract DAAL02-92-K-0037U.S. Department of Energy Contract DE-AC02-90ER-40591U.S. Navy - Office of Naval Research Grant N00014-90-J-4130Lawrence Livermore National Laboratories Subcontract B-160456National Aeronautics and Space Administration Grant NAGW-2048National Science Foundation Grant ECS-88-22475U.S. Department of Energy Grant DE-FG02-91-ER-5410
Plasma Dynamics
Contains table of contents for Section 2 and reports on four research projects.National Science Foundation Grant ECS 89-02990U.S. Air Force - Office of Scientific Research Grant AFOSR 89-0082-BU.S. Army - Harry Diamond Laboratories Contract DAAL02-89-K-0084U.S. Department of Energy Contract DE-AC02-90ER40591U.S. Navy - Office of Naval Research Grant N00014-90-J-4130Lawrence Livermore National Laboratory Subcontract B-160456National Science Foundation Grant ECS 88-22475U.S. Department of Energy Contract DE-FG02-91-ER-54109National Aeronautics and Space Administration Grant NAGW-2048U.S.-Israel Binational Science Foundation Grant 87-0057U.S Department of Energy Contract DE-AC02-78-ET-5101
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