Abstract:
An ElectroMagnetic-Mechanical Pulser can generate electron pulses at rates up to 50 GHz, energies up to 1 MeV, duty cycles up to 10%, and pulse widths between 100 fs and 10 ps. A modulating Transverse Deflecting Cavity (“TDC”) imposes a transverse modulation on a continuous electron beam, which is then chopped into pulses by an adjustable Chopping Collimating Aperture. Pulse dispersion due to the modulating TDC is minimized by a suppressing section comprising a plurality of additional TDC's and/or magnetic quadrupoles. In embodiments the suppression section includes a magnetic quadrupole and a TDC followed by four additional magnetic quadrupoles. The TDC's can be single-cell or triple-cell. A fundamental frequency of at least one TDC can be tuned by literally or virtually adjusting its volume. TDC's can be filled with vacuum, air, or a dielectric or ferroelectric material. Embodiments are easily switchable between passive, continuous mode and active pulsed mode.
Abstract:
A technique for producing a coherent beam of hard X-rays is provided. This technique is based on a short wavelength undulator that uses the fields of an electromagnetic wave to deflect a relativistic electron beam along a sinusoidal trajectory in order to cause it to emit X-rays. The undulator consists of a slow-wave structure that is energized by a second counterpropagating electron beam. Cylindrical and planar structure configurations are provided and also a mechanism for electrical and mechanical tuning to allow control over the wavelength of the emitted X-ray beam.
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 (“EMMP”) generates electron pulses at a continuously tunable rate between 100 MHz and 20-50 GHz, with energies up to 0.5 MeV, duty cycles up to 20%, and pulse widths between 100 fs and 10 ps. A dielectric-filled Traveling Wave Transmission Stripline (“TWTS”) that is terminated by an impedance-matching load such as a 50 ohm load imposes a transverse modulation on a continuous electron beam. The dielectric is configured such that the phase velocity of RF propagated through the TWTS matches a desired electron energy, which can be between 100 and 500 keV, thereby transferring electromagnetic energy to the electrons. The beam is then chopped into pulses by an adjustable aperture. Pulse dispersion arising from the modulation is minimized by a suppressing section that includes a mirror demodulating TWTS, so that the spatial and temporal coherence of the pulses is substantially identical to the input beam.
Abstract:
An ElectroMagnetic-Mechanical Pulser can generate electron pulses at rates up to 50 GHz, energies up to 1 MeV, duty cycles up to 10%, and pulse widths between 100 fs and 10 ps. A modulating Transverse Deflecting Cavity (“TDC”) imposes a transverse modulation on a continuous electron beam, which is then chopped into pulses by an adjustable Chopping Collimating Aperture. Pulse dispersion due to the modulating TDC is minimized by a suppressing section comprising a plurality of additional TDC's and/or magnetic quadrupoles. In embodiments the suppression section includes a magnetic quadrupole and a TDC followed by four additional magnetic quadrupoles. The TDC's can be single-cell or triple-cell. A fundamental frequency of at least one TDC can be tuned by literally or virtually adjusting its volume. TDC's can be filled with vacuum, air, or a dielectric or ferroelectric material. Embodiments are easily switchable between passive, continuous mode and active pulsed mode.
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 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. RF can be applied to a down-selecting TWMCS downstream of the aperture to reduce the pulse repetition rate.
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:
An ElectroMagnetic-Mechanical Pulser (“EMMP”) generates electron pulses at a continuously tunable rate between 100 MHz and 20-50 GHz, with energies up to 0.5 MeV, duty cycles up to 20%, and pulse widths between 100 fs and 10 ps. A dielectric-filled Traveling Wave Transmission Stripline (“TWTS”) that is terminated by an impedance-matching load such as a 50 ohm load imposes a transverse modulation on a continuous electron beam. The dielectric is configured such that the phase velocity of RF propagated through the TWTS matches a desired electron energy, which can be between 100 and 500 keV, thereby transferring electromagnetic energy to the electrons. The beam is then chopped into pulses by an adjustable aperture. Pulse dispersion arising from the modulation is minimized by a suppressing section that includes a mirror demodulating TWTS, so that the spatial and temporal coherence of the pulses is substantially identical to the input beam.
Abstract:
A dielectric loaded accelerator for accelerating charged particles, such as electrons, ions and/or protons, is described herein. The dielectric loaded accelerator accelerates charged particles along a longitudinal axis and towards an outlet of the accelerator. The dielectric loaded accelerator accelerates the charged particles using oscillating electromagnetic fields that propagate within the accelerator according to an electromagnetic mode. The dielectric loaded accelerator described herein includes an electromagnetic mode with a phase velocity that increases towards the outlet of the accelerator and matches a velocity of the charged particles being accelerated along the longitudinal axis of the accelerator. By matching the phase velocity of the oscillating electromagnetic fields to the velocity of the charged particles, the accelerator reduces phase slippage between the fields and the charged particles and, therefore, efficiently accelerates charged particle towards the outlet.