| Paper |
Title |
Page |
| TUP080 |
Tuning the Magnetic Transport of an Induction Linac Using Emittance
|
444 |
| |
- T. L. Houck, C. G. Brown, M. M. Ong, A. Paul, J. M. Zentler
LLNL, Livermore, California
- P. E. Wargo
Bechtel Nevada, Los Alamos, New Mexico
|
|
| |
The Lawrence Livermore National Laboratory Flash X-Ray (FXR) machine is a linear induction accelerator used to produce a nominal 20-MeV, 3-kA, 60-ns pulse width electron beam for hydrodynamic radiographs. A common figure of merit for this type of radiographic machine is the x-ray dose divided by the spot area on the bremsstrahlung converter. Several characteristics of the beam affect the minimum attainable x-ray spot size. The most significant are emittance, chromatic aberration, and beam motion. FXR is in the midst of a multi-year optimization project to reduce the spot size. This paper describes the effort to reduce beam emittance by adjusting the fields of the transport solenoids. If the magnetic transport is not correct, the beam will be mismatched and undergo envelop oscillations increasing the emittance. We measure the divergence and radius of the beam in a drift section after the accelerator by imaging the optical transition radiation (OTR) and beam envelope on a foil. These measurements are combined with transport simulations to calculate an emittance. Relative changes in the emittance can be quickly estimated allowing for an efficient, real-time study.
|
|