Abstract: A compact device called the split cavity modulator whose self-generated oscillating electromagnetic field converts a steady particle beam into a modulated particle beam. The particle beam experiences both signs of the oscillating electric field during the transit through the split cavity modulator. The modulated particle beam can then be used to generate microwaves at that frequency and through the use of extractors, high efficiency extraction of microwave power is enabled. The modulated beam and the microwave frequency can be varied by the placement of resistive wires at nodes of oscillation within the cavity. The short beam travel length through the cavity permit higher currents because both space charge and pinching limitations are reduced. The need for an applied magnetic field to control the beam has been eliminated.

Abstract: A method and an apparatus for enhancing modulation of a relativistic electron beam are described. A relativistic electron beam having been modulated is produced and passed through a superconducting passage having a periodicity in the passing direction of said beam. The periodicity is coincident with the modulation of the beam so that the modulation of the beam is enhanced by interaction between the beam and the superconducting passage through electromagnetic fields. The modulated electron beam can be used for generating microwaves at low power consumption.

Abstract: A gyrotron having a mode converter located in the path of a wave passing passage, the mode converter comprising a means for mode-converting electromagnetic wave into a radiating electromagnetic wave having an annular-shaped power distribution in a plane perpendicular to the direction in which the electromagnetic wave propagates, a ring-shaped mirror (annular mirror) for reflecting the radiating electromagnetic wave which has been converted by the mode converting means, and a waveguide tube having a kerf (i.e., a cutting portion of the tube) opposed to the annular mirror to receive the electromagnetic wave reflected by the annular mirror.

Abstract: A quasi-optical component for microwave radiation comprises a quasi-optical element (16a) which radiates incident microwave radiation along a major axis (19) and which has a characteristic transverse dimension (D) which is smaller than 50-times one wavelength. It is distinguished by the fact that a cooled absorption device (17) is provided which is arranged closely in front of the quasi-optical element (16a) in such a manner that at least one high-power secondary peak (20) of the diffraction due to the characteristic transverse dimension is destroyed.

Abstract: In a gyrotron having an annular collector for an expanded e-beam and a gyrotron output waveguide with an annular gap for passing the expanded e-beam is provided with a mode converter between the resonator and the gap to shift more energy to the waveguide central axis to decrease EM field leakage coupling through said gap.

Abstract: The invention relates to a device for producing microwave energy from an electron beam. The device includes:an electron gun (1), allowing the production of an electron beam (8) in a so-called injection zone (3);a microwave modulation circuit (7), allowing the superimposition of an alternating voltage at a given frequency on the voltage of the beam in the injection zone; the amplitude of this voltage is sufficient for ensuring, during one of its alternations, the transition between the passing state and the virtual cathode state, thus causing a modulation of the current carried by the electron beam;an output microwave circuit (4) functioning at the frequency of the modulation signal and excited by the previous modulated current.

Abstract: A quasi-optical gyrotron for the production of electromagnetic radiation in the form of mm waves has several high-power resonators. Resonators have two mirrors each lying on a resonator longitudinal axis aligned perpendicular to an electron beam axis. The electron beam axis is thus given by the path of the electrons forced to gyration by a static magnetic field. Resonator longitudinal axes are basically in a common plane perpendicular to the electron beam axis and form an angle greater than zero.

Abstract: In a quasi-optical gyrotron an electron beam (1) passes along an electron beam axis (2) and in so doing is compressed by a static magnetic field and forced into gyration, so that it excites in a quasi-optical resonator a standing alternating electro-magnetic field of given frequency. The resonator exhibits two mirrors (4a, 4b) arranged opposite to one another on a resonator axis (5) aligned perpendicular to the electron beam axis (2). In order to generate radiation in a wide frequency range, each of the two mirrors (4a, 4b) of the resonator is arranged in each case on a movable mount (8a, 8b) together with at least one further mirror (4c, 4d). In order to set a specific frequency of the alternating field, it is possible for two mirrors (4c, 4d), corresponding to one another and tuned to the desired frequency, to be brought onto the resonator axis by actuating the movable mounts (8a, 8b).

Abstract: For the purpose of generating an electron beam (5), a quasi-optical gyrotron comprises an electron-beam gun (1) with an annular cathode (2). The electron beam (5) passes along an electron beam axis (6) and in so doing is compressed by a static magnetic field and forced into gyration, so that it excites in a quasi-optical resonator a standing alternating electromagnetic field of specific wavelength. The resonator exhibits two mirrors (9a, 9b) arranged opposite to one another on a resonator axis (8) aligned perpendicular to the electron beam axis (6). In order to increase the efficiency of the gyrotron, the annular cathode (2) alternately exhibits segments of high and low emitting power such that the electron beam (5) has an azimuthally varying current density, values of low current density in the resonator coinciding spatially with nodal surfaces of the standing alternating electromagnetic field.

Abstract: In a quasi-optical gyrotron, two coils (3a, 3b) in a Helmholtz arrangement generate a static magnetic field which is axially symmetrical with respect to an electron beam axis (2). As a result, the electrons passing along the electron beam axis (2) parallel to the magnetic field are forced into gyration and excite an alternating electromagnetic field in a quasi-optical resonator. The resonator comprises two mirrors (4a, 4b) which are arranged opposite to one another on a resonator axis (5) and which exhibit a superconducting reflective surface (6a, 6b). The resonator axis (5) is aligned perpendicularly to the electron beam axis (2) between the two coils (3a, 3b). So that the superconduction is not impaired by the strong magnetic field, means for suppressing the magnetic field at the location of the mirros (4a, 4b) are provided. These means preferably comprise a yoke (10) of a material having a high magnetic permeability.

Abstract: In a quasi-optical gyrotron which exhibits a quasi-optical resonator having two mirrors (4a, 4b) which opposite one another on a resonator axis (5), the required electromagnetic radiation is coupled out by means of a hologram. In this arrangement, at least one of the two mirrors (4b) of the resonator exhibits a reflective surface (8b) provided with a hologram. The hologram is constructed in such a manner that the radiation to be coupled out is scattered in the direction of at least exactly one coupling-out axis (10), the at least exactly one coupling-out axis (10) enclosing a predetermined angle .alpha. not equal to zero with the resonator axis (5). The angle .alpha. is preferably as small as possible.

Abstract: The invention discloses a wiggler used in synchrotron radiation sources and free electron lasers, where each pole is surrounded by at least two electromagnetic coils. The electromagnetic coils are energized with different amounts of current to provide a wide tunable range of the on-axis magnetic flux density, while preventing magnetic saturation of the poles.

Abstract: In a quasi-optical gyrotron, two coils (3a, 3b) in a Helmholtz arrangement generrate a static magnetic field aligned parallel to an electron beam axis (2). As a result, the electrons passing along the electron beam axis (2) parallel to the magnetic field are forced into gyration and excite an alternating electromagnetic field in a quasi-optical resonator. The resonator comprises two mirrors (4a, 4b) arranged opposite to one another on a resonator axis (5). The resonator axis (5) is aligned perpendicularly to the electron beam axis (2) between the two coils (3a, 3b). The mirrors exhibit a mutual distance which is much greater than one half wavelength of the electromagnetic radiation. To generate a wideband radiation, at least one mirror, (4b) is moved at a high frequency by at least about one half wavelength of the electromagnetic radiation by a vibrator (10).

Abstract: Dielectric-filled longitudinal slots in the common wall of concentric circular and coaxial dielectric-lined waveguides allow microwave energy to be efficiently coupled therethrough. Such couplers are used with megawatt level gyrotrons for varied applications. One application provides a double seal waveguide vacuum window with low reflections over a wideband of frequencies. Another application provides an output coupler and window for quasi-optical gyrotrons. Still another application provides a waveguide mode converter for converting high order microwave modes, as are commonly found in waveguide cavities of high power gyrotrons, to lower-order modes suitable for low-loss transmission, such as the HE.sub.11 mode.

Abstract: The device according to the invention comprises a photocathode (1) illuminated by a luminous source (11) modulated at a high frequency F by an optical device (15) controlled at the frequency F, the optical device (15) being interposed between the luminous source and the photocathode. According to one aspect of the invention, the optical modulator (15) is controlled by a surrounding electromagnetic field at a high frequency F, in which the modulator is immersed. The electron gun device according to another aspect of the invention can be associated to a microwave circuit to obtain microwave oscillator or amplifier tubes. According to another aspect of the invention, the device supplies a pulsed electron beam for injection into particle accelerators.

Abstract: A device for the injection of electrons into an electron tube, having: a superconductive bar, a first end of which enters the tube, and an electrical supply. The bar acts as a cathode. Two anodes, a main anode and a secondary anode are placed in the tube, respectively in the place where the electrons are collected and in the place where the first end of the bar enters. The electrical supply provides for application of two voltages, a main voltage and a secondary voltage. Electrons are accelerated along the bar through the two voltages and acquire a kinetic energy which is at least equal to the energy of extraction from the superconductor, and are thus ejected outside the bar.

Abstract: In a gyrotron cavity resonator, generated energy is extracted into a symmetric set of fundamental-mode waveguides by ports disposed to couple energy in phase from the operating electromagnetic mode but in anti-phase with respect to an unwanted mode of lower cutoff frequency than the operating mode, thereby neutralizing coupling to the unwanted mode. A second set of interspersed ports may be disposed to load degenerate, orthogonal modes.

Abstract: Apparatus and method are provided for causing different groups of particles from an accelerated electron or positron beam to interact exclusively in different sections of a free electron laser. The sections may be one or several amplifiers and an oscillator. The electron beam of a single accelerator used to excite a free electron laser is directed to traverse first an amplifier section or a sequence of amplifier sections and thereafter is directed into an oscillator section where the electron beam induces lasing. If the beam source is pulsed, this invention produces the proper time synchronization of electron and laser pulses. Specifically, delay times between optical pulses are employed among the oscillator and the amplifier or amplifiers to cause the laser to oscillate on the appropriate subharmonic or subharmonics of the accelerator repetition rate so that the intervening electron pulses are used only in the amplifier or amplifiers.

Abstract: A plasma wave tube and associated operating method are described in which a pair of cold-cathode electron beam generators discharge counterpropagating electron beams into an ionizable gas, preferably hydrogen or a noble gas, within a waveguide housing. A voltage within the approximate range of 4-20 kV relative to the waveguide housing is applied to the cathodes to produce electron beams with current densities of at least about 1 amp/cm.sup.2. The beams form a plasma within the gas and couple with the plasma to produce electron plasma waves, which are non-linearly coupled to radiate electromagnetic energy in the microwave to mm-wave region. A magnetic field is established within the waveguide between the cathodes to confine the plasma, and to control the beam discharge impedance. The gas pressure is held within the approximate range of 1-100 mTorr, preferably about 10-30 mTorr, to damp plasma instabilities and sustain the beam voltages, while the magnetic field is within the approximate range of 100-500 Gauss.

Abstract: In a double disk window assembly for a waveguide, first and second dielectric disks face each other and are coupled to waveguide segments, respectively. The second dielectric disk has a central coupling section which is mechanically coupled to the center region of the first dielectric disk. The first and second dielectric disks are sealed to define a gap through which a coolant passes.

Abstract: A compact high gradient accelerator driven by a relativistic klystron is utilized to inject high energy electrons into an X-ray synchrotron radiation ring. The high gradients provided by the relativistic klystron enables accelerator structure to be much shorter (typically 3 meters) than conventional injectors. This in turn enables manufacturers which utilize high energy, high intensity X-rays to produce various devices, such as computer chips, to do so on a cost effective basis.

Abstract: In a multicavity klystron amplifier, the drift-tube bore is larger (46) in proportion to the beam size (10) in the non-interacting space between gaps (28) than its size (22) at the gaps (28). This decreases the spacecharge wavelength so that the overall physical length of the klystron is shortened.

Abstract: According to the invention, the conducting collector wall (23) on which the electrons are collected is surrounded by a coil winding (36) which is supplied with a periodically varying current, creating a slightly divergent axial magnetic field whose amplitude is periodically variable with time. The electron trajectories strike the collector wall at a grazing, nearly tangential angle, broadening the zone of impact, and the zone of impact is swept back and forth along the length of the collector, further spreading the power to be dissipated on a greater surface of the collector. Application to realization of very high power tubes or moderate power tubes with reduced collector dimensions.

Abstract: This invention relates to a high-performance gyrotron for the production of electromagnetic millimeter or submillimeter waves with a quasi-optical resonator. The latter is formed by two concave mirrors (1, 2) placed mutually opposite one another on an optical axis. For increasing the decoupling efficiency as well as for reducing the radiation into the environment the quasi-optical resonator is placed in a housing (4), which at least in sections is electrically conductive.

Abstract: A gyrotron device according to the present invention, having an electron gun for emitting an electron beam having an annular cross seciton, coils for applying a magnetic field to the electron beam emitted from the electron gun, a resonator for resonating the electron beam with microwaves and converting energy of the electron beam into microwaves, a collector for collecting the electron beam, a directional coupler for causing microwaves of a predetermined mode to pass, and a waveguide unit for guiding the microwaves from the directional coupler to an external portion.

Abstract: A coaxial cavity (CC) resonating in accordance with the fundamental mode and the electrons are injected into the median plane perpendicular to the axis. Application to the irradiation of various strip-like substances.

Abstract: A free-electron laser has a wiggler for a linear electron beam comprising two sets of magnetic polepieces 26, 28 periodically spaced along opposite sides of the beam. The polepieces of one set 28 are displaced along the beam from the other set 26 by one-half period. A uniform longitudinal magnetomotive force generates fields between polepieces having transverse components 22 alternating between the sets 26, 28, providing a very short periodicity and hence, high frequency wave radiation.

Abstract: A gyrotron interaction resonator 29 operating in a TE.sub.n1 cavity mode has an array of longitudinal slots 32 in the conductive wall 30. The slots 32 are spaced to couple to the unwanted TE.sub.n1 modes and to other modes of differing n and not to the desired mode. Wave-absorptive material 34 spaced from the inner cavity wall 28 and coupled to slots 32 absorbs the unwanted modes.

Abstract: A gyrotron device including an electron gun for emitting a hollow electron beam, solenoid coils for generating magnetic fields so as to produce a cyclotron movement to the electron beam emitted from the electron gun, a plurality of ring mirrors arranged in the direction of the beam axis of the electron beam, and an optical resonator for resonating the electromagnetic waves produced when the electron beam is injected along the magnetic field lines. The optical resonator includes a slotted reflecting mirror so that a portion of the electromagnetic waves propagating within the resonator is reflected upstream to intersect and interact with the electron beam plural times. In order to maximize energy absorption by the electromagnetic waves, the solenoid coils are separately excited so as to shift the radius of the electron beam .lambda./4 within the resonator, .lambda. being the wavelength of electromagnetic waves.

Abstract: A high electric field gradient electron accelerator utilizing short duration, microwave radiation, and capable of operating at high field gradients for high energy physics applications or at reduced electric field gradients for high average current intermediate energy accelerator applications. Particles are accelerated in a smooth bore, periodic undulating waveguide, wherein the period is so selected that the particles slip an integral number of cycles of the r.f. wave every period of the structure. This phase step of the particles produces substantially continuous acceleration in a traveling wave without transverse magnetic or other guide means for the particle.

Abstract: An orotron for generating near millimeter wavelength radiation at a selectable output frequency within a wide frequency range, in which the orotron output power is automatically tuned electronically at the selected output frequency. A piezoelectric electromechanical positioning device is connected between the two mirrors forming the open resonator of the orotron to determine the mirror separation in accordance with a position control signal. The electron beam acceleration voltage, which determines the orotron output frequency, and the position control signal are adjusted simultaneously so as to tune the output power at a single oscillation mode of the orotron resonator over a wide frequency range. In the preferred embodiment, the actual output frequency is detected and compared with the selected output frequency, and the beam acceleration voltage and mirror separation simultaneously adjusted to continuously tune and maintain the orotron output at the selected frequency.

Abstract: A tunable millimeter wave source in which accelerated electrons are directed into a bending magnet and emit broadband radiation in the millimeter wavelength portion of the spectrum. The electrons are produced by an electron gun using a portion of the microwave energy output from a RF source. The remainder of the microwave energy from the RF source is used to drive an RF linear accelerator which accelerates the electrons and directs them into the bending magnet. An interferometer may be used to select radiation of a particular frequency from the broadband output of the source. In a second embodiment, the source is provided with a plurality of output apertures, and a plurality of respective interferometers are used to select radiation of a number of desired discrete frequencies.

Abstract: In gyrotron devices, pitch factor and efficiency are directly proportional. When the pitch factor is increased, however, a larger starting current is needed. The available power supply thus limits the pitch factor and subsequently, the efficiency of the device. The present invention is a gyrotron device in which the pitch factor is adjustable. When starting the gyrotron the pitch factor is set to a low level and only a small starting current is required. After the device has been started, the pitch factor can be increased to increase the oscillation efficiency.

Abstract: A system for providing a compact, high power particle accelerator powered by a modulated intense relativistic electron beam. In a preferred embodiment a first source develops a high power intense relativistic electron beam (IREB). A modulating apparatus modulates the IREB with a low power level RF signal to produce a high power MIREB. All of the kinetic energy from the high power MIREB is then stored as a high level of electromagnetic or RF energy in an accelerating apparatus. A particle beam from a source is modulated with the RF signal to establish a phase coherency between the modulated particle beam and the stored RF energy before it is passed through the accelerating apparatus. This phase coherent particle beam is accelerated by the stored RF energy as it drains this energy from the accelerating apparatus during its passage through the accelerating apparatus.

Abstract: This invention discloses an improved undulator comprising a plurality of electromagnet poles located along opposite sides of a particle beam axis with alternate north and south poles on each side of the beam to cause the beam to wiggle or undulate as it travels generally along the beam axis and permanent magnets spaced adjacent the electromagnetic poles on each side of the axis of said particle beam in an orientation sufficient to reduce the saturation of the electromagnet poles whereby the field strength of the electromagnet poles can be increased beyond the normal saturation levels of the electromagnetic poles.

Abstract: A sub-nanosecond rise time megavolt pulse generator is disclosed. The generator utilizes an induction energy store together with electron beams for generating a sub-nanosecond high voltage pulse wave-front. The electron beams are deflected to establish the wave-front. In a preferred form multiple electron beams together with a waveguide of particular shape provide simultaneous converging wave-fronts that are directed to a local area.

Abstract: An apparatus and method for generating high power electro magnetic radiation in the millimeter or submillimeter range axial injection and adiabatic compression of an electron beam using large electric fields in an evacuated AXIOM (Axial Injection Orbitron Maser).

Abstract: A device (10) for producing high-powered and coherent microwaves is described. The device comprises an evacuated, cylindrical, and hollow real cathode (20) that is driven to inwardly field emit relativistic electrons. The electrons pass through an internally disposed cylindrical and substantially electron-transparent cylindrical anode (24), proceed toward a cylindrical electron collector electrode (26), and form a cylindrical virtual cathode (32). Microwaves are produced by spatial and temporal oscillations of the cylindrical virtual cathode (32), and by electrons that reflex back and forth between the cylindrical virtual cathode (32) and the cylindrical real cathode (20).

Abstract: The invention relates to multiple beam lasertrons. The n (n: integer greater than 1) electron beams of the lasertron are obtained from the same laser beam from which n secondary laser beams are extracted, by occultation, which are deflected respectively towards the n photocathodes of the lasertron.

Abstract: An electron gun for a vacuum tube employs a mounting element having an inner annular section with a defined thickness made to predetermined dimensional tolerances. The cathode subassembly is positioned on one surface of the annular section and a grid electrode is located on the opposing surface. When the mounting element is set within the vacuum tube facing the anode electrode, the location of the cathode subassembly and grid electrode in the mounting element establishes a precise cathode-to-anode spacing and the electrodes are properly aligned and concentric to a central axis along which the electron beam travels.

Abstract: A foilless intense relativistic electron beam generator uses an ionized cnel to guide electrons from a cathode passed an anode to a remote location.

Abstract: The present invention provides a vircator with improved efficiency. An elongated anode is aligned with an elongated cathode so as to produce an elongated virtual cathode when a direct current voltage source is electrically connected to the elongated cathode. A surface wave having a velocity near the velocity of light will be produced on the virtual cathode. Waveguide means enclosing the virtual cathode is disposed so as to propagate microwave radiation in a direction parallel to the direction of elongation of the cathode, anode and virtual cathode. The waveguide is designed to match the phase velocity of the microwave to the velocity of the virtual cathode surface wave.

Abstract: An IREB is guided through a curved path by ionizing a channel in a gas with electrons from a filament, and confining the electrons to the center of the path with a magnetic field extending along the path. The magnetic field is preferably generated by a solenoid extending along the path.

Abstract: The invention envisages control devices acting on the laser to vary in time the electron/photon interaction, means proceeding to a State I in which they alter the optimal conditions for laser amplification; and a State II in which that reestablish said optimal conditions, which control devices permit the improvement of the peak amplitude and stability of the laser pulses and the rate and stability of the pulse period. According to another aspect of this invention, the two states are alternated, preferably periodically or almost periodically. The duration of State I should be selected by comparison with the characteristics of the electron packet and, in particular of the relaxation time observed for said packet. If the duration of State II is set to a value to be comparable to or longer than the electron relaxation time, the peak amplitude of the laser pulses is increased. The duration of State II should be selected by comparison with the natural macropulse width.

Abstract: An external cavity klystron vacuum tube has a ceramic cylindrical wall surrounded by an external cavity within which is an output probe. The cylindrical wall section is sealed at its ends to other components of the tube--to enable the interior to be evacuated--by sealing means such as to avoid a sharp edge projecting inwardly towards the interior of the cavity.

Abstract: An improved radiation source is disclosed, exploiting the spontaneous radiation generated from the interaction of an electron beam and a conductive grating. Conditions are defined for generating coherent or noncoherent radiation, and for extending the tunability of the radiation source from millimeter, IR, visible and UV wavelengths to x-ray wavelengths, and for generating multiple wavelengths simultaneously. Conditions are disclosed for enhancing the intensity of the spontaneous radiation, anf for modulating the radiation.

Abstract: A variable frequency RFQ linear accelerator has a sequence of variable inductance coils connected at intervals along the electrode vanes, such that each coil together with the corresponding section of the vanes forms an LC resonant circuit having a resonant frequency equal to the operating frequency of the accelerator. The variable inductance coils are each comprised of a helical bifilar coil, with each filament of a given coil being connected to one pair of vane electrodes on opposite sides of the beam axis, and a movable shorting bar is provided for each bifilar coil to vary the inductance. The helical bifilar coils in adjacent sections are disposed on opposite sides of the beam axis, the axes of the coils on either side being parallel to the beam axis and mutually coincident.

Abstract: A device for guiding an electron beam from an electron gun to a microwave resonator in a microwave source operating according to the gyrotron principle, including a beam duct for guiding the electron beam, wherein the beam duct encloses the electron beam and has an electrically highly conductive surface area. For damping unwanted wave modes inside the beam duct, a plurality of damping openings are provided in the surface area of the beam duct. The characteristic aperture size (a) of the damping openings is larger than the wavelength of the modes to be damped. A particularly simple implementation employs wire mesh with an appropriate mesh size used as the material for the surface area of the beam duct.

Abstract: An ion or electron beam is steered or focussed by a circular magnetic field produced by passing a large electrical current through a straight conducting wire, the magnetic field being co-axial with the wire. Annular beams of charged particles coaxial with the straight wire can be focussed onto a circular spot or, depending upon the entry radius of the annular beam and the magnetic field strength, can be induced to follow a looping trajectory. The effect of the steering or focussing system can be enhanced by the provision of a cylindrical conductor which is co-axial with the straight conducting wire and maintained at a voltage sufficient to produce the desired particle trajectory such that the particle beam passes between the wire and the cylindrical conductor. The beam steering or focussing systems is applicable to the fields of beam current density intensification, ion implantation, ion separation and free electron lasers.

Abstract: A helix type traveling wave tube comprises an evacuated envelope containing an electron gun assembly at one end thereof for forming and projecting a beam of electrons over an elongated beam path to an electron collector electrode at the opposite end of the envelope. A helix slow-wave circuit is arranged along the beam path intermediate the electron gun and the beam collector for electromagnetic interaction with the beam. In order to extract an amplified signal from the downstream end of the slow wave circuit, there is provided an coaxial line including an outer conductor air-tightly fixed at one end thereof to the evacuated envelope and an inner conductor having one end connected to an output end of the slow wave circuit. An output waveguide is air-tightly fixed to the other end of the coaxial line outer conductor in such a manner the other end of the coaxial line inner conductor extending into the output waveguide.