AMERICAN SCIENCE AND ENGINEERING, INC. Patent applications |
Patent application number | Title | Published |
20140233707 | Versatile Beam Scanner with Fan Beam - A versatile beam scanner for generating a far-field scanned pencil beam, and, alternatively, a far-field pencil beam. An angle selector limits the angular extent of an inner fan beam emitted by a source of penetrating radiation. The source and angle selector may be translated, along a direction parallel to a central axis of a multi-aperture unit, in such a manner as to generate a scanned far-field pencil beam, when rings of apertures are interposed between the source and an inspected target, or, alternatively, a far-field fan beam, when no ring of apertures is interposed. | 08-21-2014 |
20140192958 | Dynamic Dose Reduction in X-Ray Inspection - Methods and an x-ray system for dynamically regulating x-ray dose. An x-ray beam is generated and collimated at a source collimator and detected after the x-ray beam traverses an inspected object. A filter may be dynamically interposed by translation of the filter between a focal spot of the source and the source collimator in such a manner as to maintain the portion of the x-ray beam that traverses the inspected object below a specified limit. Alternatively, an aperture of the source collimator may be varied in size or position relative to the focal spot. | 07-10-2014 |
20140044238 | Multiple Image Collection and Synthesis for Personnel Screening - An apparatus and method for inspecting personnel or their effects. A first and second carriage each carries a source for producing a beam of penetrating radiation incident on a given subject. A positioner provides for relative motion of each beam vis-à-vis the subject in a motion, the vertical component of which is one-way. A detector receives radiation produced by at least one of the sources after the radiation interacts with the subject. | 02-13-2014 |
20130343520 | X-Ray Backscatter Mobile Inspection Van - Systems and methods for inspecting an object with a scanned beam of penetrating radiation. Scattered radiation from the beam is detected, in either a backward or forward direction, as is radiation transmitted through the inspected object. The source of penetrating radiation is concealed within an enclosure of a road-worthy vehicle, and detected with a large-area uncollimated detector similarly concealed within the enclosure. | 12-26-2013 |
20130287176 | X-Ray Tube with Rotating Anode Aperture - An x-ray tube for generating a sweeping x-ray beam. A cathode is disposed within a vacuum enclosure and emits a beam of electrons attracted toward an anode. The anode is adapted for rotation with respect to the vacuum enclosure about an axis of rotation. At least one collimator opening corotates with the anode within the vacuum enclosure, such that a swept x-ray beam is emitted. | 10-31-2013 |
20130235977 | Electromagnetic Scanning Apparatus for Generating a Scanning X-ray Beam - An apparatus for generating a scanned beam of penetrating electromagnetic radiation. An electron beam is incident on a succession of specific locations on a concave anode which emits electromagnetic waves in response thereto, in such a way that electromagnetic waves exiting from an aperture scan over a range of angles within a scan plane in response to angular scanning of the electron beam. The x-ray beam is extracted from the apparatus via one or more exit apertures in the back hemisphere, on the side of the anode onto which the electron beam impinges. | 09-12-2013 |
20130230140 | Methods for High Energy X-ray Imaging Using Remotely-Aligned Arcuate Detector Array - Methods for inspecting contents of a container. High-energy penetrating radiation collimated into a fan beam illuminates an inspected container from one side, while a plurality of detector plates are disposed on the opposite side of the container. Each detector plate has a plurality of detector modules, each of which, in turn, is disposed on a remotely activated alignment and has multiple detector elements. A controller governs the orientation of each of the plurality of detector plates based at least on the detector signal generated by its detector elements such that each detector element of each detector module of each detector plate may be aligned to within a specified fraction of the transverse dimension of the fan beam as measured at the exit slot. | 09-05-2013 |
20130208857 | X-Ray Inspection using Wavelength-Shifting Fiber-Coupled Scintillation Detectors - A detector and methods for inspecting material on the basis of scintillator coupled by wavelength-shifting optical fiber to one or more photo-detectors, with a temporal integration of the photo-detector signal. An unpixelated volume of scintillation medium converts energy of incident penetrating radiation into scintillation light which is extracted from a scintillation light extraction region by a plurality of optical waveguides. This geometry provides for efficient and compact detectors, enabling hitherto unattainable geometries for backscatter detection and for energy discrimination of incident radiation. Additional energy-resolving transmission configurations are enabled as are skew- and misalignment compensation. | 08-15-2013 |
20130202089 | Convertible Scan Panel for X-Ray Inspection - An x-ray inspection system using backscatter of an x-ray beam emitted through a scan panel contiguous with, but of a material distinct from, an enclosure that contains an x-ray source by which the x-ray beam is generated. The scan panel is contoured in such a manner as to be visibly blended with a shape characterizing the enclosure. In some embodiments, the beam traverses multiple scan panels, where one or more of the scan panels may be selected for beam filtration properties. The scan panel may be disposed interior to a sliding door, and may be structured to serve as a scatter shield. | 08-08-2013 |
20130195248 | Hand-Held X-Ray Backscatter Imaging Device - Apparatus for imaging items behind a concealing barrier. A source of penetrating radiation is contained entirely within a housing. A spatial modulator forms the penetrating radiation into a beam and sweeps the beam to irradiate an inspected object. A detector generates a scatter signal based on penetrating radiation scattered by contents of the inspected object, and a sensor senses motion relative to a previous position of the apparatus with respect to the inspected object. A processor receives the scatter signal and generates an image of the contents of the inspected object based at least on the scatter signal. The housing may be adapted for singled-handed retention by an operator | 08-01-2013 |
20130136230 | System and Methods for Multi-Beam Inspection of Cargo in Relative Motion - X-ray inspection of moving cargo based on acquiring multiple image lines at one time or substantially at one time. An X-ray source with multiple-beam electron beam targets creates multiple parallel X-ray fan beams. X-ray inspection systems and methods employ such multiple-beam sources for purposes of inspecting fast moving cargo. | 05-30-2013 |
20130101090 | Methods to Perform Backscatter Inspection of Complex Targets in Confined Spaces - Embodiments of backscatter inspection systems include features to enable inspection of irregular surfaces, tight spacer, and other hard-to-reach places. Some embodiments include arms that maneuver a scan head with at least three degrees of freedom, and some embodiments include arms that maneuver a scan head with at least seven degrees of freedom. Some embodiments include proximity detectors on a scan head or base, detect contact with an object being inspected, and to slow or stop the motion of the system accordingly. Some compact embodiments scan the interior of an object from within, and include a rotating, low-energy source of penetrating radiation, and at least one backscatter detector, which may be stationary, or may rotate with the source. | 04-25-2013 |
20130064353 | Forward- and Variable-offset Hoop for Beam Scanning - An apparatus for forming a beam of energetic particles and for scanning the beam of particles with respect to an inspected object. The apparatus has a source of energetic particles characterized by an effective beam origin and a rotating hoop having at least one aperture, such that the effective beam origin of the source is closer to the inspected object than the axis of rotation of the rotating hoop. A collimating structure disposed interior to the rotating hoop collimates emission by the source into a fan beam prior to impinging on the rotating hoop. In some embodiments, the effective beam origin may be moved with respect to the axis of rotation of the hoop. | 03-14-2013 |
20130039463 | Top-Down X-Ray Inspection Trailer - A system and method for inspecting a vehicle by means of one or more sources and detectors of penetrating radiation. The source(s) and detector(s) are carried on a mobile conveyance and deployed at a point of operation. One source swings away from the conveyance on a deployable member, such as a boom, such that the source can irradiate a vehicle from above or below. A detector deploys outwardly from the mobile conveyance, remaining mechanically coupled to the mobile conveyance in a position in a horizontal plane, such that the detector intercepts penetrating radiation from the source positioned above the inspected vehicle, which penetrating radiation has interacted with the inspected vehicle. A ramp may be provided to allow the inspected vehicle to be driven to a position between the vertically irradiating source and a transmission detector. | 02-14-2013 |
20130039453 | Radiation Threat Detection - Systems and methods for detecting clandestine fissile or radioactive material on the basis of emitted radiation and particles (such as neutrons and alpha particles) arising from within the material. Emission by the fissile or radioactive material is detected in conjunction with a conventional x-ray imaging system that includes an external source of illuminating penetrating radiation, at least one detector configured to detect at least the penetrating radiation and to generate a detector signal, and a processor configured as a detector signal discriminator to generate an output indicating whether the detector signal is triggered by an origin other than illuminating penetrating radiation. Active and passive modes of detection are described by some embodiments. Other embodiments are directed toward neutron detection, gamma ray detection with energy resolution, and designs of detectors to enhance the detection of clandestine nuclear material. | 02-14-2013 |
20130028376 | Stowable Arcuate Detector Array - A mobile scanning system and methods for inspecting contents of a container. Multiple detector plates are arrayed along an arcuate member coupled to a conveyance with wheels, capable of road travel. A source generates high-energy penetrating radiation that irradiates each of the detector plates from a single position. The arcuate member is disposed, during the course of operation of the system, in a vertical plane. The system has one actuator for rotating the arcuate member about a horizontal pivot into a horizontal plane, and a second actuator for further rotating the arcuate member, once rotated into the horizontal plane, about a vertical pivot, so that the arcuate member is contained, for purposes of transport, entirely within a volume defined by a rectangular prism that does not extend horizontally outward from the conveyance beyond any of its wheels. | 01-31-2013 |
20130003936 | Adjustable-Jaw Collimator - An adjustable collimator for shaping a beam of particles, such as for purposes of inspecting contents of a container. The adjustable collimator has an obscuring element substantially opaque to passage of the particles in a propagation direction that is radial with respect to the axis of rotation of a ring of apertures. A gap in the obscuring element may be characterized by a length taken along a long dimension and a jaw spacing taken along narrow dimension, and at least one of the length of the gap and the jaw spacing is subject to adjustment, either manual or automatic. The adjustable collimator may be disposed either inside or outside the ring of apertures, and, in some embodiments, the jaw spacing may be a function of distance along the long dimension relative to an edge of the gap. | 01-03-2013 |
20120269319 | Versatile X-Ray Beam Scanner - Apparatus for interrupting and/or scanning a beam of penetrating radiation, such as for purposes of inspecting contents of a container. A source, such as an x-ray tube, generates a fan beam of radiation effectively emanating from a source axis, with the width of the fan beam collimated by a width collimator, such as a clamshell collimator. An angular collimator, stationary during the course of scanning, limits the extent of the scan, and a multi-aperture unit, such as a hoop, or a nested pair of hoops, is rotated about a central axis, and structured in such a manner that the total beam fluence incident on a target is conserved for different fields of view of the beam on the target. The central axis of hoop rotation need not coincide with the source axis. | 10-25-2012 |
20120263276 | Backscatter System with Variable Size of Detector Array - A variable-geometry backscatter inspection system has a radiation detector array including one or more backscatter radiation detectors. The position of a second backscatter radiation detector is variable with respect to the position of a first backscatter radiation detector, so that the size of the detector array may be varied by moving the second radiation detector into or out of a predefined alignment with the first radiation detector. The system may include a movable base, and at least one of the detectors is movable with respect to the base. Methods of inspecting an object include forming a detector array by moving a second radiation detector into a predefined alignment with a first radiation detector, illuminating the object with a pencil beam of penetrating radiation, and detecting backscattered radiation with the detector array. | 10-18-2012 |
20120236990 | X-Ray Inspection Based on Concealed Transmission Detection - Systems and methods for inspecting an object with a scanned beam of penetrating radiation. Scattered radiation from the beam is detected, in either a backward or forward direction, as is radiation transmitted through the inspected object. The source of penetrating radiation is concealed within an enclosure of a road-worthy vehicle, while a transmission detector is concealed within a separate enclosure. | 09-20-2012 |
20120221144 | Disruptor Guidance System and Methods Based on Scatter Imaging - A system and method for guiding a disruptor robot in disruption of an explosive device. The system includes a source of penetrating radiation, having a coordinated position on the robot with respect to a disrupter coupled to robot, and at least one detector for detecting radiation produced by the source and scattered by the explosive device. An analyzer produces an image of the explosive device and facilitates identification of a disruption target of the explosive device. A controller positions the disruptor with respect to the explosive device so that the disruptor is aimed at the disruption target. | 08-30-2012 |
20120201356 | Backscatter Energy Analysis for Classification of Materials based on Positional Non-Commutativity - A system and methods for characterizing regions within, or on, an inspected object, wherein a lower-Z scattering material and a higher-Z material may both lie along a common line of sight. The inspected object is scanned with penetrating radiation characterized by an energy distribution, and penetrating radiation scattered by the inspected object is detected in a manner that generates two detector signals that distinguish between materials of higher and lower effective atomic number under distinct sets of conditions with respect to the energy distribution of the penetrating radiation. An image is generated, based on a function of the two detector signals, as is a differential image, so as to allow distinction of higher-Z and lower-Z materials. | 08-09-2012 |
20120106714 | Versatile X-Ray Beam Scanner - Apparatus for interrupting and/or scanning a beam of penetrating radiation, such as for purposes of inspecting contents of a container. A source, such as an x-ray tube, generates a fan beam of radiation effectively emanating from a source axis, with the width of the fan beam collimated by a width collimator, such as a clamshell collimator. An angular collimator, stationary during the course of scanning, limits the extent of the scan, and a multi-aperture unit, such as a hoop, or a nested pair of hoops, is rotated about a central axis, and structured in such a manner that beam flux incident on a target is conserved for different fields of view of the beam on the target. The central axis of hoop rotation need not coincide with the source axis. | 05-03-2012 |
20120093289 | System and Methods for Intrapulse Multi-energy and Adaptive Multi-energy X-ray Cargo Inspection - Methods and systems for x-ray inspection of an object using pulses whose spectral composition varies during the course of each pulse. A temporal sequence of pulses of penetrating radiation is generated, each pulse characterized by an onset and by a spectral content that evolves with time subsequent to the onset. The pulses are formed into a beam that is scanned across the object. The penetrating radiation from the beam that has traversed the object is detected, generating a detector signal. The detector signal is processed to derive at least one material characteristic of the object, such as effective atomic number, on the basis of temporal evolution of the detector signal during the course each pulse of the sequence of pulses. The detector signal is separately acquired for multiple time intervals relative to the pulse onset, and processed to obtain values corresponding to multiple-energy analysis of the transmitted radiation. The time intervals may be predetermined, or else adapted based on features of the detected signal. | 04-19-2012 |
20120093288 | Remotely-Aligned Arcuate Detector Array for High Energy X-ray Imaging - A scanning system and methods for inspecting contents of a container. High-energy penetrating radiation collimated into a fan beam illuminates an inspected container from one side, while a plurality of detector plates are disposed on the opposite side of the container. Each detector plate has a plurality of detector modules, each of which, in turn, is disposed on a remotely activated alignment and has multiple detector elements. A controller governs the orientation of each of the plurality of detector plates based at least on the detector signal generated by its detector elements such that each detector element of each detector module of each detector plate may be aligned to within a specified fraction of the transverse dimension of the fan beam as measured at the exit slot. | 04-19-2012 |
20120033791 | Backscatter X-Ray Inspection Van with Top-Down Imaging - A system and method for inspecting a vehicle or other object by means of two sources and one or more detectors of penetrating radiation. The sources and detector(s) are carried on a mobile conveyance and deployed at a point of operation. One source irradiates an inspected object from within an enclosure, while a second source swings away from the conveyance on a deployable member, such as a boom, such that the second source can irradiate the vehicle from above. A backscatter image of the inspected object is based at least in part on radiation from the second source scattered by the inspected object. | 02-09-2012 |
20110309253 | Detector with Active Collimators - an apparatus and methods for detecting radiation. A plurality of substantially parallel active collimation vanes are sensitive to the incident radiation for generating at least a first detection signal, and a rear detector detects incident radiation that passes between the substantially parallel active collimation vanes and generates a second detection signal. A processor receives and processes both the first and second detection signals. The active collimator vanes may be enclosed within a light-tight enclosure, and a first photodetector may be provided for detecting scintillation arising at the active collimation vanes, while a second photodetector may be provided for detecting scintillation arising at the rear detector. | 12-22-2011 |
20110293066 | Low-Cost Position-Sensitive X-Ray Detector - A detector and methods for producing x-ray images, more particularly based on x-rays transmitted through an inspected object. A scintillating region is translated along a path within a cross section of a beam, the cross section taken in a plane distal to the object with respect to a source of the beam. Light emitted by the scintillator region is detected, thereby generating a detection signal, the detection signal is received by a processor which generates an image signal, and an image depicting transmitted penetrating radiation is formed on the basis of the image signal. | 12-01-2011 |
20110249798 | Scatter Attenuation Tomography using a Monochromatic Radiation Source - A system and methods for characterizing an inspected object on the basis of attenuation between identified regions of scattering and a plurality of detectors. An incident beam of substantially monochromatic penetrating radiation is generated by a source, which may be a radioactive source. The incident beam is characterized by a propagation axis and a source energy. Radiation scattered by the object is detected by means of a plurality of detector elements disposed about the beam of penetrating radiation, each detector element generating a detector signal characterizing a detected energy of scattered radiation. The detector signal provides for determining a displacement for each scattering point of the object relative to a fiducial position on the propagation axis of the incident beam, based upon the detected energy of the scattered radiation. By calculating the attenuation of penetrating radiation between pairs of scattering voxels, a tomographic image is obtained characterizing the three-dimensional distribution of attenuation in the object of one or more energies of penetrating radiation, and thus of material characteristics. | 10-13-2011 |
20110164726 | Multiple Image Collection and Synthesis for Personnel Screening - An apparatus and method for inspecting personnel or their effects. A first and second carriage each carries a source for producing a beam of penetrating radiation incident on a given subject. A positioner provides for relative motion of each beam vis-à-vis the subject in a motion, the vertical component of which is one-way. A detector receives radiation produced by at least one of the sources after the radiation interacts with the subject. | 07-07-2011 |
20110163236 | Scintillation-Cherenkov Detector and Method for High Energy X-Ray Cargo Container Imaging and Industrial Radiography - An inspection system, and corresponding methods, employing a detector for characterizing high energy penetrating radiation transmitted through an inspected object. The detector produces a detector signal that is due to both scintillation and Cherenkov processes. The scintillation and Cherenkov components of the detector signal are discriminated and processed to obtain separate measures of relative attenuation of higher and lower energy penetrating radiation in a target intervening between a source of penetrating radiation and the detector. In certain embodiments of the invention, scintillation and Cherenkov components of a detector signal are discriminated on the basis of distinct spectral features, or, alternatively, by processing temporal characteristics of the signal of a single photodetector. | 07-07-2011 |
20110075808 | X-Ray Inspection Based on Scatter Detection - Systems and methods for inspecting an object with a scanned beam of penetrating radiation. Scattered radiation from the beam is detected, in either a backward or forward direction. Characteristic values of the scattered radiation are compared to expected reference values to characterize the object. Additionally, penetrating radiation transmitted through the inspected object may be combined with scatter information. In certain embodiments, the inspected field of view is less than 0.1 steradians, and the detector is separate from the source of penetrating radiation and is disposed, with respect to the object, such as to subtend greater than 0.5 steradians in the field of view of the object. | 03-31-2011 |
20110026674 | Walk-Through Shoe Inspection System - An apparatus and method for x-ray inspection of footwear while the footwear is worn on the feet of walking persons. A source of penetrating radiation, such as an x-ray tube, mounted on one side of a system, provides a fan beam of penetrating radiation contained in a substantially vertical plane, while a detector, disposed on the opposing side of the system, detects penetrating radiation that has traversed the footwear. A controller creates an image of the footwear. | 02-03-2011 |
20110026673 | Top-Down X-Ray Inspection Trailer - A system and method for inspecting a vehicle by means of one or more sources and detectors of penetrating radiation. The source(s) and detector(s) are carried on a mobile conveyance and deployed at a point of operation. One source swings away from the conveyance on a deployable member, such as a boom, such that the source can irradiate a vehicle from above or below. A detector deploys outwardly from the mobile conveyance, remaining mechanically coupled to the mobile conveyance in a position in a horizontal plane, such that the detector intercepts penetrating radiation from the source positioned above the inspected vehicle, which penetrating radiation has interacted with the inspected vehicle. A ramp may be provided to allow the inspected vehicle to be driven to a position between the vertically irradiating source and a transmission detector. | 02-03-2011 |
20110017917 | Multiple Image Collection and Synthesis for Personnel Screening - An apparatus and method for inspecting personnel or their effects. A first and second carriage each carries a source for producing a beam of penetrating radiation incident on a given subject. A positioner provides for relative motion of each beam vis-à-vis the subject in a motion, the vertical component of which is one-way. A detector receives radiation produced by at least one of the sources after the radiation interacts with the subject. | 01-27-2011 |
20100104069 | Multiple Image Collection and Synthesis for Personnel Screening - An apparatus and method for inspecting personnel or their effects. A first and second carriage each carries a source for producing a beam of penetrating radiation incident on a subject. A positioner provides for synchronized relative motion of each carriage vis-á-vis the subject in a direction having a vertical component. A detector receives radiation produced by at least one of the sources after the radiation interacts with the subject. | 04-29-2010 |
20100034347 | Scatter Attenuation Tomography - A system and methods for characterizing an inspected object on the basis of attenuation determined from pair-wise illuminated voxels. A beam of penetrating radiation characterized by a propagation direction and an energy distribution is scanned relative to an object, while scatter detectors with collimated fields-of-view detect radiation scattered by each voxel of the inspected object that is intercepted by the incident beam of penetrating radiation. By calculating the attenuation of penetrating radiation between pairs of voxels illuminated sequentially by the incident beam, a tomographic image is obtained characterizing the three-dimensional distribution of attenuation in the object of one or more energies of penetrating radiation, and thus of various material characteristics. | 02-11-2010 |
20090268871 | X-Ray Inspection with Contemporaneous and Proximal Transmission and Backscatter Imaging - An X-ray imaging inspection system for bags and packages. Transmission imaging is performed using a fan beam and a segmented detector, while scatter imaging is performed with a scanned pencil beam, with both beams active simultaneously. Cross-talk between the beams is mitigated by a combination of shielding, scatter detector design, positioning and orientation, and image processing. Image processing subtracts the measured radiation scattered from the transmission beam into the scatter detectors, reducing cross-talk | 10-29-2009 |
20090257555 | X-Ray Inspection Trailer - An inspection system, and inspection methods, based upon an imaging enclosure characterized by an enclosing body. A source of penetrating radiation and a detector module are concealed entirely within the body of a conveyance such as a trailer. A characterizing value or an image is formed with respect to an inspected object that is disposed entirely outside the conveyance and the characterizing value or image is made available to a remotely disposed operator. Additional detectors may be disposed distally to the inspected object and may detect transmitted, or forward-scattered, penetrating radiation. | 10-15-2009 |
20090175412 | Radiation Threat Detection - Systems and methods for detecting clandestine fissile or radioactive material on the basis of emitted radiation and particles (such as neutrons and alpha particles) arising from within the material. Emission by the fissile or radioactive material is detected in conjunction with a conventional x-ray imaging system that includes an external source of illuminating penetrating radiation, at least one detector configured to detect at least the penetrating radiation and to generate a detector signal, and a processor configured as a detector signal discriminator to generate an output indicating whether the detector signal is triggered by an origin other than illuminating penetrating radiation. Active and passive modes of detection are described by some embodiments. Other embodiments are directed toward neutron detection, gamma ray detection with energy resolution, and designs of detectors to enhance the detection of clandestine nuclear material. | 07-09-2009 |
20090116617 | Multiple Image Collection and Synthesis for Personnel Screening - An apparatus and method for inspecting personnel or their effects. A first and second carriage each carries a source for producing a beam of penetrating radiation incident on a subject. A positioner provides for synchronized relative motion of each carriage vis-à-vis the subject in a direction having a vertical component. A detector receives radiation produced by at least one of the sources after the radiation interacts with the subject. | 05-07-2009 |
20090103686 | X-Ray Imaging with Continuously Variable Zoom and Lateral Relative Displacement of the Source - An inspection system based on penetrating radiation in which the field of view of a scan may be varied. First and second primary limiting apertures are provided for interposition between a source of penetrating radiation and an inspected object. This allows for significantly increasing the flux of penetrating radiation on this narrowed region of interest, thereby advantageously improving detectability. The relative position of the source with respect to either the first or the second aperture may be varied, in a direction either along, or transverse to, a normal to the aperture. | 04-23-2009 |
20080310591 | Backscatter Inspection Portal - A system and method for inspecting an object with multiple sources of substantially coplanar penetrating radiation. Irradiation of the inspected object by the sources is temporally sequenced such that the source of detected scattered radiation is unambiguous. Thus, multiple views of the inspected object may be obtained and image quality may be enhanced. | 12-18-2008 |
20080211431 | Pulse-to-Pulse-Switchable Multiple-Energy Linear Accelerators Based on Fast RF Power Switching - A method and apparatus for modulating at least one of energy and current of an electron beam in a linac for fast switching of particle beam energy on a time scale comparable with, and shorter than, the interval between linac pulses. Such modulation may be achieved by dividing, in a coupler, a radio-frequency (RF) field into field components and coherently adding these components in a phase shifting section to selectively direct the RF field to a chosen section of the linac. The phase shifting section may include at least one arm containing at least one fast switch and at least one phase changer. In specific embodiments, the phase shifting section may include an electronically controlled plasma switch and a plasma short. | 09-04-2008 |