Abstract: A self-aligning, high-power, free electron laser (FEL) oscillator 10, comprises a self-aligning feedback, element 12 located near the electron beam input end 14 l of the FEL wiggler 16; a partially transmitting stimulated Brillouin scattering (SBS) plasma mirror 18 located near the output end 20 of the laser wiggler 16; and a plurality of laser beam expansion elements 32-32.sup.n located in succession on the path of the resulting output laser beam 34 for magnifying the output laser beam 34 to a desired output diameter. A totally reflecting, removable start-up mirror 30 is located between SBS plasma mirror 18 and laser beam expansion elements 32-32.sup.n. The removable start-up mirror 30 provides feedback until the SBS threshold is reached.

Abstract: An apparatus and method for enhancing the efficiency of a free electron laser, (10). A plurality of electrodes, (28) are imbedded in an electrically insulating vacuum tube, (18) enclosing the electron beam, (14) and its copropagating electromagnetic wave. A variable computer controlled high voltage d.c. power supply, (29) is connected to the electrodes, (28) for energizing the electrodes, (28) at saturation indicated by detectors, (30) thereby converting d.c. electric potential to electromagnetic radiation without gain degradation.

Abstract: A free electron laser in which the electron beam 12 is sent through the field of a quadrupole magnet 16 which may be untapered or tapered. The beam 12 is sent through the magnet 16 spaced from the symmetry axis of the magnet's poles 22 but on the focusing plane 20 of the quadrupole magnet 16.

Abstract: A source of coherent electromagnetic radiation capable of generating or amplifying waves in the centimeter, millimeter, and submillimeter wavelength range. An annular beam of gyrating electrons is produced which is then compressed to its paraxial position by means of a solenoid magnetic field around the wave-guide. This electron beam is also subjected to a transverse motion in an interaction region by a longitudinal rippled (wiggler) magnetic field. Such a field is generated by a periodic assembly of rings magnetized in the axial direction. The electron beam during its accelerated motion generates or amplifies coherent electromagnetic radiation in the centimeter, millimeter, or submillimeter range.

Abstract: A telescopic pole having an elongated tubular handle section, an elongated tubular tool section, and one or more intermediate tubular sections. Each of the tool and intermediate sections is slidably telescoped within the next lowermost section and is provided with a manually releasable locking device which coacts with the next lowermost section for holding the sections in a fully extended position. The locking device includes a cylindrical locking member which is sealingly connected to the tubular section on which it is mounted. The locking device is provided with a small bleed hole which provides communication between the interior of the tubular section and the surrounding atmosphere for limiting the escape of air from one tubular section when the adjacent tubular section is being telescopically collapsed therein.