Relations Between Hermite And Laguerre Gaussian Modes

Relations between Hermite (HG) and Laguerre (LG) Gaussian modes are derived. With these, a LG mode is written as a sum of HG modes, and vice versa. These mode relations are derived from addition identities between a Laguerre polynomial and a pair of Hermite polynomials. The addition relations are derived in two appendices. One figure illustrates the contents of a LG mode in terms of HG modes while a second figure shows the translation in the opposite direction. © 1993 IEE

Computer simulation of mode evolution in long pulse FELs

The longest pulse FEL to date is presently under construction. The bandwidth will critically depend on the optical mode interaction. The set of coupled, nonlinear equations for modes evolution are solved numerically. Due to the strong mode coupling in long pulse FELs, the outcome is single mode operation. © 1994

Analytical Study Of Multimode Competition

A theoretical analysis of the multimode competition problem in a FEL is presented. For the three-mode problem the system is mathematically described by a set of three coupled differential equations. The coupling coefficients in the equations are obtained from a perturbation expansion of the current driving the FEL. The only asymptotically stable solutions are single-mode. Then a system of any number of modes is studied. In this case also only single-mode solutions are asymptotically stable. © 1990

<title>High-power electrostatic-accelerator FELs for power beaming</title>

Electrostatic-accelerator free-electron lasers (EAFELs) are used to generate intense, CW, single-mode, laser radiation for space power beaming applications such as envisioned by the project SELENE. Using present electrostatic accelerator technology (≤ MV), together with the electron gun and electron collector technology developed for the UC Santa Barbara FEL we discuss several laser configurations. The first one entails using a single 25 MV, 2 A, DC electron beam system to produce 100 kW power at 1.54 μm. At the same wavelength and with the same accelerator the power can be increased up to 3.1 MW using a 20 A electron gun. Still, with the same type of accelerator but with higher currents, 0.84 μm can be generated. A third configuration discussed in this paper requires two high voltage accelerators to reach electron energies of up to 50 MV. The major advantage of using EAFELs is that true CW, single-mode operation can be achieved with a minimum expected wall power efficiency of 25%. We also discuss ways to produce 10 MW average power, that would require additional technology developments

High-Power Electrostatic-Accelerator Fel Program For Power Beaming

We discuss details of a technical plan that will lead to the development of a 1 MW, continuous wave (CW), efficient, near infrared electrostatic-accelerator FEL for power beaming applications. Among the advantages of our technical approach are: (a) true cw or pulsed operation is possible; (b) better than 20% wall-power efficiency can be achieved, (c) existing electrostatic accelerator technology will be employed, and (d) only low levels of unwanted ionizing radiation will be produced. We propose to achieve our final objective in three technical steps. The first step is currently under implementation at the University of Central Florida. The main thrust of the present program is to show 1 kW, CW, far-infrared FEL operation with a 1.7 MV electrostatic accelerator. The goal of the second step is to reach 60 kW FEL power in the middle-infrared region using the TANDAR (Argentinian Tandem) accelerator (V = +17 MV). For the third step we propose using a combination of two high voltage tandem accelerators (V = +25, -25 MV) to achieve the final goal of 1 MW, CW operation in the near-infrared region

Hybrid resonators for FELs

For FELs operating at far-infrared and submillimeter wavelengths hybrid resonators are the most convenient. The modes of such resonators are studied in the elliptic-cylinder (EC) system of coordinates. Both scalar and vector solutions of the wave equation are obtained and electric field lines are shown in a figure. © 1994

Coherent Radiation Reaction In Free-Electron Sources

Spontaneous coherent radiation is an important process in existing and proposed experiments. Energy conservation in theoretical simulation of these experiments requires that the corresponding radiation reaction be taken into account. Existing conventional proposals for radiation reaction forces are valid when electrons emit independently, ignoring collective aspects of the radiation. In this paper we present radiation reaction prescriptions in which coherent effects are taken into account. © 1995 The American Physical Society

SASE X-ray radiation via Lienard-Wiechert fields

We present three-dimensional numerical results of self-amplified X-ray wiggler radiation from a relativistic electron beam using Lienard-Wiechert forces to drive self-consistently the motion of electrons. The exact three-dimensional self-consistent motion of a beam of electrons gives rise to exact three-dimensional radiation fields which can be calculated with very few approximations. As an example of this approach, we report here results of three-dimensional X-ray coherent wiggler radiation calculations for a short relativistic electron pulse

Confirmation Of Single-Mode Fel Operation

Experimental results from the UC Santa Barbara FEL are reviewed. At saturation, macroscopic and microscopic time-structure records give clear evidence of discrete time structure and single dominant longitudinal-mode operation. © 1990

Electrostatic-Accelerator Fels For Power Beaming

We propose the use of electrostatic-accelerator free-electron lasers (EAFELs) to generate intense, CW, single-mode, laser radiation for space power beaming applications such as envisioned by the project SELENE. We discuss two basic FEL configurations employing present electrostatic accelerator technology (≤25 MV), together with the electron gun and electron collector beam recovery technology first developed for the UC Santa Barbara FEL. © 1995