# FULL ELECTROMAGNETIC FEL SIMULATION VIA THE LORENTZ-BOOSTED FRAME TRANSFORMATION

## Abstract

Numerical electromagnetic simulation of some systems containing charged particles with highly relativistic directed motion can by speeded up by orders of magnitude by choice of the proper Lorentz-boosted frame. A particularly good application for calculation in a boosted frame isthat of short wavelength free-electron lasers (FELs) where a high energy electron beam with small fractional energy spread interacts with a static magnetic undulator. In the optimal boost frame (i.e., the ponderomotive rest frame), the red-shifted FEL radiation and blue-shifted undulator field have identical wavelengths and the number of required longitudinal grid cells and time-steps for fully electromagnetic simulation (relative to the laboratory frame) decrease by factors of gamma^2 each. In theory, boosted frame EM codes permit direct study of FEL problems for which the eikonal approximation for propagation of the radiation field and wiggler-period-averaging for the particle-field interaction may be suspect. We have adapted the WARP code to apply this method to several electromagnetic FEL problems including spontaneous emission, strong exponential gain in a seeded, single pass amplifier configuration, and emission from e-beams in undulators with multiple harmonic components. WARP has a standard relativistic macroparticle mover and a fully 3-D electromagnetic field solver. We discuss our boosted frame results andmore »

- Authors:

- Publication Date:

- Research Org.:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

- Sponsoring Org.:
- Accelerator& Fusion Research Division

- OSTI Identifier:
- 991033

- Report Number(s):
- LBNL-3961E

TRN: US1007430

- DOE Contract Number:
- DE-AC02-05CH11231

- Resource Type:
- Conference

- Resource Relation:
- Conference: 32nd International Free Electron Laser Conference FEL 2010, Malmo, Sweden, 23-27 August 2010

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 43; AMPLIFIERS; CHARGED PARTICLES; CONFIGURATION; EIKONAL APPROXIMATION; ELECTROMAGNETIC FIELDS; ELECTRON BEAMS; FREE ELECTRON LASERS; HARMONICS; LASERS; RADIATIONS; SIMULATION; TRANSFORMATIONS; WAVELENGTHS; WIGGLER MAGNETS; Free-electron laser; Lorentz boosted-frame simulation

### Citation Formats

```
Fawley, William, and Vay, Jean-Luc.
```*FULL ELECTROMAGNETIC FEL SIMULATION VIA THE LORENTZ-BOOSTED FRAME TRANSFORMATION*. United States: N. p., 2010.
Web.

```
Fawley, William, & Vay, Jean-Luc.
```*FULL ELECTROMAGNETIC FEL SIMULATION VIA THE LORENTZ-BOOSTED FRAME TRANSFORMATION*. United States.

```
Fawley, William, and Vay, Jean-Luc. Mon .
"FULL ELECTROMAGNETIC FEL SIMULATION VIA THE LORENTZ-BOOSTED FRAME TRANSFORMATION". United States. https://www.osti.gov/servlets/purl/991033.
```

```
@article{osti_991033,
```

title = {FULL ELECTROMAGNETIC FEL SIMULATION VIA THE LORENTZ-BOOSTED FRAME TRANSFORMATION},

author = {Fawley, William and Vay, Jean-Luc},

abstractNote = {Numerical electromagnetic simulation of some systems containing charged particles with highly relativistic directed motion can by speeded up by orders of magnitude by choice of the proper Lorentz-boosted frame. A particularly good application for calculation in a boosted frame isthat of short wavelength free-electron lasers (FELs) where a high energy electron beam with small fractional energy spread interacts with a static magnetic undulator. In the optimal boost frame (i.e., the ponderomotive rest frame), the red-shifted FEL radiation and blue-shifted undulator field have identical wavelengths and the number of required longitudinal grid cells and time-steps for fully electromagnetic simulation (relative to the laboratory frame) decrease by factors of gamma^2 each. In theory, boosted frame EM codes permit direct study of FEL problems for which the eikonal approximation for propagation of the radiation field and wiggler-period-averaging for the particle-field interaction may be suspect. We have adapted the WARP code to apply this method to several electromagnetic FEL problems including spontaneous emission, strong exponential gain in a seeded, single pass amplifier configuration, and emission from e-beams in undulators with multiple harmonic components. WARP has a standard relativistic macroparticle mover and a fully 3-D electromagnetic field solver. We discuss our boosted frame results and compare with those obtained using the ?standard? eikonal FEL simulation approach.},

doi = {},

journal = {},

number = ,

volume = ,

place = {United States},

year = {Mon Aug 16 00:00:00 EDT 2010},

month = {Mon Aug 16 00:00:00 EDT 2010}

}