Topic

# Perveance

About: Perveance is a research topic. Over the lifetime, 751 publications have been published within this topic receiving 6565 citations.

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21 May 2001-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment

TL;DR: In this paper, a hybrid implicit algorithm was developed to treat dense plasmas accurately, and simulations of neutralized ballistic transport showed improved transport efficiency for a 4-GeV, 4-kA Pb ion beam by including a 1013 cm−3 plasma at initialization.

Abstract: Heavy ion-driven inertial confinement fusion requires efficient transport of the ion beam over several meters from the entrance of the accelerator to the target. Currently considered transport modes with high perveance beams require significant charge and current neutralization that will likely require pre-existing dense plasmas. We have developed a hybrid implicit algorithm to treat dense plasmas accurately. Using this algorithm, simulations of neutralized ballistic transport show improved transport efficiency for a 4-GeV, 4-kA Pb ion beam by including a 1013 cm−3 plasma at initialization.

233 citations

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01 Jan 2007

TL;DR: In this paper, the authors present an overview of the main components of a two-dimensional Curvilinear Beams with translation symmetry (Lomax-Kirstein method).

Abstract: PREFACE. Introduction. I.1 Outline of the Book. I.2 List of Symbols. I.3 Electromagnetic Fields and Potentials. I.4 Principle of Least Action. Lagrangian. Generalized Momentum. Lagrangian Equations. I.5 Hamiltonian. Hamiltonian Equations. I.6 Liouville Theorem. I.7 Emittance. Brightness. PART I ELECTRON BEAMS. 1 Motion of Electrons in External Electric and Magnetic Static Fields. 1.1 Introduction. 1.2 Energy of a Charged Particle. 1.3 Potential-Velocity Relation (Static Fields). 1.4 Electrons in a Linear Electric Field e0E kx. 1.5 Motion of Electrons in Homogeneous Static Fields. 1.6 Motion of Electrons in Weakly Inhomogeneous Static Fields. 1.6.1 Small Variations in Electromagnetic Fields Acting on Moving Charged Particles. 1.7 Motion of Electrons in Fields with Axial and Plane Symmetry. Busch's Theorem. 2 Electron Lenses. 2.1 Introduction. 2.2 Maupertuis's Principle. Electron-Optical Refractive Index. Differential Equations of Trajectories. 2.3 Differential Equations of Trajectories in Axially Symmetric Fields. 2.4 Differential Equations of Paraxial Trajectories in Axially Symmetric Fields Without a Space Charge. 2.5 Formation of Images by Paraxial Trajectories. 2.6 Electrostatic Axially Symmetric Lenses. 2.7 Magnetic Axially Symmetric Lenses. 2.8 Aberrations of Axially Symmetric Lenses. 2.9 Comparison of Electrostatic and Magnetic Lenses. Transfer Matrix of Lenses . 2.10 Quadrupole lenses. 3 Electron Beams with Self Fields. 3.1 Introduction. 3.2 Self-Consistent Equations of Steady-State Space-Charge Electron Beams. 3.3 Euler's Form of a Motion Equation. Lagrange and Poincare' Invariants of Laminar Flows. 3.4 Nonvortex Beams. Action Function. Planar Nonrelativistic Diode. Perveance. Child-Langmuir Formula. r- and T-Modes of Electron Beams. 3.5 Solutions of Self-Consistent Equations for Curvilinear Space-Charge Laminar Beams. Meltzer Flow. Planar Magnetron with an Inclined Magnetic Field. Dryden Flow. 4 Electron Guns. 4.1 Introduction. 4.2 Pierce's Synthesis Method for Gun Design. 4.3 Internal Problems of Synthesis. Relativistic Planar Diode. Cylindrical and Spherical Diodes. 4.4 External Problems of Synthesis. Cauchy Problem. 4.5 Synthesis of Electrode Systems for Two-Dimensional Curvilinear Beams with Translation Symmetry (Lomax-Kirstein Method). Magnetron Injection Gun. 4.6 Synthesis of Axially Symmetric Electrode Systems. 4.7 Electron Guns with Compressed Beams. Magnetron Injection Gun. 4.8 Explosive Emission Guns. 5 Transport of Space-Charge Beams. 5.1 Introduction. 5.2 Unrippled Axially Symmetric Nonrelativistic Beams in a Uniform Magnetic field. 5.3 Unrippled Relativistic Beams in a Uniform External Magnetic Field. 5.4 Cylindrical Beams in an Infinite Magnetic Field. 5.5 Centrifugal Electrostatic Focusing. 5.6 Paraxial-Ray Equations of Axially Symmetric Laminar Beams. 5.7 Axially Symmetric Paraxial Beams in a Uniform Magnetic Field with Arbitrary Shielding of a Cathode Magnetic Field. 5.8 Transport of Space-Charge Beams in Spatial Periodic Fields. PART II MICROWAVE VACUUM ELECTRONICS. 6 Quasistationary Microwave Devices. 6.1 Introduction. 6.2 Currents in Electron Gaps. Total Current and the Shockley-Ramo Theorem. 6.3 Admittance of a Planar Electron Gap. Electron Gap as an Oscillator. Monotron. 6.4 Equation of Stationary Oscillations of a Resonance Self-Excited Circuit. 6.5 Effects of a Space-Charge Field. Total Current Method. High-Frequency Diode in the r-Mode. Llewellyn-Peterson Equations. 7 Klystrons. 7.1 Introduction. 7.2 Velocity Modulation of an Electron beam. 7.3 Cinematic (Elementary) Theory of Bunching. 7.4 Interaction of a Bunched Current with a Catcher Field. Output Power of A Two-Cavity Klystron. 7.5 Experimental Characteristics of a Two-Resonator Amplifier and Frequency-Multiplier Klystrons. 7.6 Space-Charge Waves in Velocity-Modulated Beams. 7.7 Multicavity and Multibeam Klystron Amplifiers. 7.8 Relativistic Klystrons. 7.9 Reflex Klystrons. 8 Traveling-Wave Tubes and Backward-Wave Oscillators (O-Type Tubes). 8.1 Introduction. 8.2 Qualitative Mechanism of Bunching and Energy Output in a TWTO. 8.3 Slow-Wave Structures. 8.4 Elements of SWS Theory. 8.5 Linear Theory of a Nonrelativistic TWTO. Dispersion Equation, Gain, Effects of Nonsynchronism, Space Charge, and Loss in a Slow-Wave Structure. 8.6 Nonlinear Effects in a Nonrelativistic TWTO. Enhancement of TWTO Efficiency (Velocity Tapering, Depressed Collectors). 8.7 Basic Characteristics and Applications of Nonrelativistic TWTOs. 8.8 Backward-Wave Oscillators. 8.9 Millimeter Nonrelativistic TWTOs, BWOs, and Orotrons. 8.10 Relativistic TWTOs and BWOs. 9 Crossed-Field Amplifiers and Oscillators (M-Type Tubes). 9.1 Introduction. 9.2 Elementary Theory of a Planar MTWT. 9.3 MTWT Amplification. 9.4 M-type Injected Beam Backward-Wave Oscillators (MWO, M-Carcinotron). 9.5 Magnetrons. 9.6 Relativistic Magnetrons. 9.7 Magnetically Insulated Line Oscillators. 9.8 Crossed-Field Amplifiers. 10 Classical Electron Masers and Free Electron Lasers. 10.1 Introduction. 10.2 Spontaneous Radiation of Classical Electron Oscillators. 10.3 Stimulated Radiation of Excited Classical Electron Oscillators. 10.4 Examples of Electron Cyclotron Masers. 10.5 Resonators of Gyromonotrons (Free and Forced Oscillations). 10.6 Theory of a Gyromonotron. 10.7 Subrelativistic Gyrotrons. 10.8 Elements of Gyrotron Electron Optics. 10.9 Mode Interaction and Mode Selection in Gyrotrons. Output Power Systems. 10.10 Gyroklystrons. 10.11 Gyro-Traveling-Wave Tubes. 10.12 Applications of Gyrotrons. 10.13 Cyclotron Autoresonance Masers. 10.14 Free Electron Lasers. Appendixes. 1. Proof of the 3/2 Law for Nonrelativistic Diodes in the r-Mode. 2. Synthesis of Guns for M-Type TWTS and BWOS. 3. Magnetic Field in Axially Symmetric Systems. 4. Dispersion Characteristics of Interdigital and Comb Structures. 5. Electromagnetic Field in Planar Uniform Slow-Wave Structures. 6. Equations of Free Oscillations of Gyrotron Resonators. 7. Derivation of Eqs. (10.66) and (10.67). 8. Calculation of Fourier Coefficients in Gyrotron Equations. 9. Magnetic Systems of Gyrotrons. References. Index.

200 citations

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TL;DR: The results of a comprehensive diode study conducted using a pulsed high-current electron accelerator are reported in this article, where time-dependent analysis of right-cylindrical graphite cathodes has shown evidence of the field emission character of the cold-cathode diode.

Abstract: The results of a comprehensive diode study conducted using a pulsed high‐current electron accelerator are reported Time‐dependent analysis of right‐cylindrical graphite cathodes has shown evidence of the field emission character of the cold‐cathode diode The effects of cathode whiskers or microprojections on the diode response have been observed Within a few nanoseconds after the voltage is applied to the diode, the whiskers explode to form cathode flares The observed diode perveance throughout the remainder of the pulse can be explained in terms of the expansion of the plasma cathode formed by the merger of many cathode flares Cathode plasma velocities ranged from approximately 2 to 3 cm/μsec The observed diode behavior was consistent with that predicted by previous studies of high‐voltage vacuum breakdown

191 citations

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TL;DR: In this article, the beam divergence and perveance of a single aperture three electrode extraction system using helium ions at energies between 10 and 30 keV were investigated. But the most critical parameter was the ratio of the radius of the first aperture to the distance between the first and second electrodes, the highest current density being obtained at values of this ratio less than 0.5.

Abstract: Experimental results are given for the perveance and beam divergence of a single aperture three electrode extraction system using helium ions at energies between 10 and 30 keV. The aperture radii, the electrode thicknesses, and the spacings were varied and from the results a preferred design was obtained for use in a multiaperture array. The most critical parameter was the ratio (S) of the radius of the first aperture to the distance between the first and second electrodes, the highest current density being obtained at values of this ratio less than 0.5. The optimum beam divergence observed corresponded to a Gaussian beam profile with a width (ω) of ± 1.2° at 2 m from the source. The measured perveance at small values of S and at minimum ω lay between 75% and 90% of the value predicted on the basis of a simple model using the Langmuir‐Blodgett formula for the spherical diode.

163 citations

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General Electric

^{1}TL;DR: In this article, a planar-anode cathode was designed for use in a line-focus, planar anode tube with a slot in which the emitter is situated, an adjacent face region which is planar and angled so as to properly form the initial electron beam, a recess to allow the initial beam to be accelerated without significant shaping, and an overhanging portion which completes the electron beam forming.

Abstract: An x-ray tube has at least one approximately planar electron emitter and an emitter-cup cathode configured to provide an electron beam of substantially greater perveance and beam compression ratio than otherwise obtainable with conventional cathode designs. The cup is optimized for use in a line-focus, planar-anode tube and has a slot in which the emitter is situated, an adjacent face region which is planar and angled so as to properly form the initial electron beam, a recess to allow the initial electron beam to be accelerated without significant shaping, and an overhanging portion which completes the electron beam forming.

116 citations