# Accession Number:

## ADA300212

# Title:

## Picosecond Demodulation and Coherent Electron Beams.

# Descriptive Note:

## Final rept.,

# Corporate Author:

## DUKE UNIV DURHAM NC DEPT OF PHYSICS

# Personal Author(s):

# Report Date:

## 1994-05-01

# Pagination or Media Count:

## 154.0

# Abstract:

Fourier theory states that a time domain signal can be represented in the frequency domain with no loss of information. Because of this equivalence, it is possible to make frequency domain measurements on a signal and, using Fourier theory, determine the time domain parameters of the source. These principles form the basis for using frequency domain measurements to characterize the real time operational characteristics of the relativistic electron beam of a free electron laser FEL. By using a Fourier transform spectrometer FTS to measure the millimetersub-millimeter spectrum emitted by a pulsed relativistic electron beam, the temporal electron beam pulse duration and shape are characterized. This technique is used to measure a 1.3 picosecond relativistic electron bunch. In addition, we are able to resolve changes in electron bunch characteristics between the beginning and end of a train of bunches. Preliminary work has begun correlating electron pulse shape to FEL optical operation. Finally, variations in the controls of the electron beam system are correlated with changes in the electron bunch measured usin the FTS. Unlike other techniques that destructively interact with the electron beam, this technique is totally passive and results in negligible perturbation in the electron bunch hence this technique can be used for direct real-time non-destructive

# Descriptors:

- *ELECTRON BEAMS
- *FREE ELECTRON LASERS
- FOURIER TRANSFORMATION
- OPTIMIZATION
- REAL TIME
- PARAMETERS
- COHERENCE
- AUTOCORRELATION
- PASSIVE SYSTEMS
- WAVEGUIDES
- MILLIMETER WAVES
- POWER SPECTRA
- LASER BEAMS
- OPTICAL INTERFEROMETERS
- CHARGE DENSITY
- SUBMILLIMETER WAVES
- DEMODULATION
- TIME DOMAIN
- FREQUENCY DOMAIN
- TIME SIGNALS
- SHORT PULSES
- FOURIER SPECTROMETERS
- THERMIONIC EMISSION
- RELATIVITY THEORY
- RELATIVISTIC ELECTRONS
- FIELD THEORY
- LINEAR ACCELERATORS

# Subject Categories:

- Lasers and Masers
- Particle Accelerators