MOOAB1
LANL, Los Alamos, New Mexico, USA
The MaRIE 1.0 X-FEL requires an electron beam at 12 GeV with 100pC bunch charge, 0.2 μm RMS normalized transverse emittance, and 0.15% RMS slice energy spread. These requirements place significant constraints upon the use of techniques, such as laser heaters, which have enabled other X-FELs to reach their design goals. In this paper, we present the current baseline design and performance of the MaRIE 1.0 linac, highlight current and anticipated challenges and describe potential alternate approaches for meeting our design performance goals.
LANL, Los Alamos, New Mexico, USA
We extend the well-known 1D CSR analytic model into higher dimensions and develop a simple numerical algorithm based on the Lienard-Wiechert formula for the CSR field of a stiff beam. The CSR numerical model includes the 2D/3D spatial dependence of the field and is accurate for arbitrary beam energy. It also removes the singularity in space charge field presented in a 1D model. Good agreement is obtained with 1D CSR analytic result for FEL related beam parameters but deviations are also found for low-energy or large spot size beams and off-axis fields. To conduct self-consistent beam dynamics study, we also employ fully electromagnetic Particle-In-Cell (PIC) simulations for CSR modeling. The relatively large numerical phase error and anisotropy in the standard PIC algorithm is improved with a high order Finite Difference Time Domain scheme. We benchmark PIC results with our new numerical model. Detail self-consistent PIC simulations of the CSR fields and beam dynamics will be presented and discussed.
Northern Illinois University, DeKalb, Illinois, USA
LANL, Los Alamos, New Mexico, USA
Fermilab, Batavia, USA
Earlier experiments at Fermilab’s A0 Photoinjector Laboratory demonstrated successful transverse-to-longitudinal emittance exchange (EEX) using a transverse-deflecting cavity (TDC) located between two identical doglegs. Such a design has the disadvantage of transversely displacing the beam. An alternative is an EEX beamline designed out of a variable R56 bunch compressor chicane. In this paper, we present designs and simulation comparisons for several emittance-exchanger beamlines, including the double-dogleg and chicane designs, as well as variations of the chicane design that allow for increasing its dispersion which proportionally decreases the field-strength requirements on the TDC. These comparisons are performed with PIC models of space charge and coherent synchrotron radiation.