Abstract: A TEM sample holder enables simultaneous cooling and RF irradiation of a sample. The sample is suspended in a hole that penetrates through a sample stage formed by a dielectric plate having a lower metallic ground layer and an upper metallic lead. The sample stage is supported by an evacuated hollow tube extending from a cryogenic chamber, such as a liquid nitrogen or helium Dewar. A coaxial conductor extends from an ambient connector through the cryogenic chamber and hollow tube to the sample stage, a center conductor and surrounding metallic shield thereof being in thermal and electrical communication with the metallic lead and metallic ground layer respectively of the sample stage, and the metallic shield being is in direct thermal communication with the cryogenic chamber. The coaxial conductor thereby enables simultaneous cooling and RF irradiation of the sample during TEM measurements. Embodiments include a temperature sensor and heater.

Abstract: In embodiments, a linac electron beam excited X-ray source weighing less than 50 pounds, and having a volume less than 1 cubic foot, injects electrons from an RF-excited, diamond tip cathode into a dielectric accelerator tube of diameter less than 10 mm, where the electrons are RF-accelerated to 1-4 MeV. A focusing channel having a plurality of annular permanent magnets can surround the dielectric tube, and a vacuum can be maintained in the tube by a getter pump. The accelerating RF can be 10 GHz or higher. The X-ray source can be powered by a rechargeable battery for more than an hour. Embodiments can be transported within a case having a display attached to an interior surface of its lid. An X-ray head can be removed from the case and extended up to 10 feet while remaining interconnected with the case by a flexible conduit.

Abstract: An electromagnetic mechanical pulser implements a transverse wave metallic comb stripline TWMCS kicker having inwardly opposing teeth that retards a phase velocity of an RF traveling wave to match the kinetic velocity of a continuous electron beam, causing the beam to oscillate before being chopped into pulses by an aperture. The RF phase velocity is substantially independent of RF frequency and amplitude, thereby enabling independent tuning of the electron pulse widths and repetition rate. The TWMCS further comprises an electron pulse picker (EPP) that applies a pulsed transverse electric field across the TWMCS to deflect electrons out of the beam, allowing only selected electrons and/or groups of electrons to pass through. The EPP pulses can be synchronized with the RF traveling wave and/or with a pumping trigger of a transverse electron microscope (TEM), for example to obtain dynamic TEM images in real time.

Abstract: An electromagnetic mechanical pulser implements a transverse wave metallic comb stripline TWMCS kicker having inwardly opposing teeth that retards a phase velocity of an RF traveling wave to match the kinetic velocity of a continuous electron beam, causing the beam to oscillate before being chopped into pulses by an aperture. The RF phase velocity is substantially independent of RF frequency and amplitude, thereby enabling independent tuning of the electron pulse widths and repetition rate. The TWMCS further comprises an electron pulse picker (EPP) that applies a pulsed transverse electric field across the TWMCS to deflect electrons out of the beam, allowing only selected electrons and/or groups of electrons to pass through. The EPP pulses can be synchronized with the RF traveling wave and/or with a pumping trigger of a transverse electron microscope (TEM), for example to obtain dynamic TEM images in real time.

Abstract: In embodiments, a linac electron beam excited X-ray source weighing less than 50 pounds, and having a volume less than 1 cubic foot, injects electrons from an RF-excited, diamond tip cathode into a dielectric accelerator tube of diameter less than 10 mm, where the electrons are RF-accelerated to 1-4 MeV. A focusing channel having a plurality of annular permanent magnets can surround the dielectric tube, and a vacuum can be maintained in the tube by a getter pump. The accelerating RF can be 10 GHz or higher. The X-ray source can be powered by a rechargeable battery for more than an hour. Embodiments can be transported within a case having a display attached to an interior surface of its lid. An X-ray head can be removed from the case and extended up to 10 feet while remaining interconnected with the case by a flexible conduit.

Abstract: An electromagnetic mechanical pulser implements a transverse wave metallic comb stripline TWMCS kicker having inwardly opposing teeth structured to retard a phase velocity of an RF traveling wave propagated therethrough to match the kinetic velocity of a continuous electron beam simultaneously propagated therethrough. The kicker imposes transverse oscillations onto the beam, which is subsequently chopped into pulses by an aperture. The RF phase velocity is substantially independent of RF frequency and amplitude, thereby enabling independent tuning of the electron pulse widths and repetition rate. The exterior surface of the kicker is conductive, thereby avoiding electron charging. In embodiments, various elements of the kicker and/or aperture can be mechanically varied to provide further tuning of the pulsed electron beam. A divergence suppression section can include a mirror TWMCS and/or magnetic quadrupoles.

Abstract: A technique is presented to extract electromagnetic radiation from a dielectric loaded waveguide consisting of a layer or layers of dielectric material enclosed in a metallic conducting jacket. The electromagnetic radiation generated in the dielectric waveguide by a charged particle beam or otherwise generated as input to the waveguide. Dielectric loaded waveguides used for generation (or transport) of electromagnetic radiation at frequencies above 100 GHz have dimensions in the sub-mm range. Due to difficulty in the fabrication of a conventional broadband horn-like antenna to extract electromagnetic radiation from the structure because of the large impedance mismatch between the dielectric loaded waveguide and free space, the designing and fabricating aperture of antennas are formed as part of the dielectric waveguide and utilizes an angle cut or a set of apertures machined into the dielectric loaded waveguide to ensure broadband power extraction with minimal return loss and high directivity.

Abstract: A resonant apparatus such as a resonant waveguide module in an RF particle accelerator includes an unbrazed joint that provides a reliable vacuum seal and RF contact between resonators with precisely controlled internal geometry. The joint can be disassembled and reassembled without degradation. Hard, stainless steel end faces include knife edges pressed into a copper central component, such as a gasket. The knife edges extend the waveguide interiors without gaps or interruptions. The central component serves as a coupling iris or other functional component of the resonant apparatus, thereby allowing the central component to have substantial dimensions that inhibit mechanical distortions thereof. The waveguides and knife edges can be copper plated. Embodiments include embedded passages and/or recesses used for cooling, radiation shielding, magnetic focusing coils, and/or electron optics element formed by permanent magnets.

Abstract: The present invention provides a technique for constructing compact, high gradient magnetic lenses for charged particle beam focusing. Methods for adjusting the focusing strength of the lenses are provided, based on thermal control, mechanical motion of the magnetic chips within the yoke. The present invention is a method for designing and fabricating permanent magnet focusing elements that are compact, simple to construct, and having a large, adjustable focusing strength. Applications include beamlines for THz radiation sources, free electron lasers, wakefield accelerators and any other charged particle devices that require a compact beamline.