The Child–Langmuir Law (CL), discovered a century ago, gives the maximum current that can be transported across a planar diode in the steady state. As a quintessential example of the impact of space charge shielding near a charged surface, it is central to the studies of high current diodes, such as high power microwave sources, vacuum microelectronics, electron and ion sources, and high current drivers used in high energy density physics experiments. CL remains a touchstone of fundamental sheath physics, including contemporary studies of nanoscale quantum diodes and nano gap based plasmonic devices. Its solid state analog is the Mott–Gurney law, governing the maximum charge injection in solids, such as organic materials and other dielectrics, which is important to energy devices, such as solar cells and light emitting diodes. This paper reviews the important advances in the physics of diodes since the discovery of CL, including virtual cathode formation and extension of CL to multiple dimensions, to the ...

100 years of the physics of diodes

Recent developments to the MICHELLE electron gun and collector design tool are reported in this paper. The MICHELLE code is a new finite-element (FE) two-dimensional and three-dimensional electrostatic particle-in-cell code that has been designed to address the recent beam optics modeling and simulation requirements for vacuum electron devices, ion sources, and charged-particle transport. Problem classes specifically targeted include depressed collectors, gridded-guns, multibeam guns, sheet-beam guns, and ion thrusters. The focus of the development program is to combine modern FE techniques with improved physics models. The code employs a conformal mesh, including both structured and unstructured mesh architectures for meshing flexibility, along with a new method for accurate, efficient particle tracking. New particle emission models for thermionic beam representation are included that support primary emission, with an advanced secondary emission model. This paper reports on three significant advances to MICHELLE over the past year; hybrid structured/unstructured mesh support, a time-domain electrostatic algorithm, and an ion plasma model with charge exchange.

Recent developments to the MICHELLE 2-D/3-D electron gun and collector modeling code

A technological breakthrough is embodied in the successful demonstration of an extended interaction klystron (EIK) amplifier, which has produced over 7.5 kW of peak output power at W-band (94 GHz). An efficiency of ${\sim}{17\%}$ has been achieved with a depressed collector. The EIK is driven by a 20-kV, 4-A sheet beam in a permanent magnet solenoid, with 99% beam current transmission from gun to collector. Key features that contribute to the success of this device are: 1) tight beam focusing and correspondingly narrow beam tunnel, which are made possible by the solenoidal focusing and which provide high interaction impedance and high gain per unit length and 2) the incorporation of design elements to stabilize the inherently over-moded circuit. Measured performance agrees well with 3-D particle-in-cell simulations.

Demonstration of a Multikilowatt, Solenoidally Focused Sheet Beam Amplifier at 94 GHz

The development of microwave-tube simulator suite (MTSS) is reported. MTSS is an integrated full-featured software package for microwave-tube analysis and design. It includes a friendly user-interface module and three physics simulators. Microwave-tube design environment is the user-interface module, which provides a powerful solid-modeling front end and graphical and computational postprocessing functionality. Electron optics simulator (EOS) is a fully 3-D finite-element design tool for microwave-tube electron guns and collectors. An EOS is used to design gridded guns, multibeam guns, and anisotropic collectors. A high-frequency circuit simulator is an advanced 3-D electromagnetic (EM) simulation tool for RF components, which has two solution methods based on a finite-integration technique and a finite-element method. Beam-wave interaction simulator (BWIS) is a design tool for electron beam and EM-wave interaction in microwave tubes. The 1-D, 2-D, and 3-D multifrequency nonlinear beam-wave interactions for helix traveling-wave tubes have been implemented in BWIS. The architecture, features, theory, and design of MTSS are presented.

Theory and Design of Microwave-Tube Simulator Suite

This article explores the history and diversity of this remarkable technology, with emphasis on advances in vacuum-electronic amplifiers, including the microwave power module (MPM), that have been enabled by the ongoing development of modeling and simulation tools These physics-based codes, enabled by rapid advances in computational hardware, allow simulation-based design and optimization of complex vacuum-electronic circuits The growth of satellite-based digital communications technology over the past decade has opened lucrative commercial opportunities for vacuum-electronic amplifiers This exciting new area requires the efficient production of high-frequency power and the ability to handle spectrally efficient modulations within stringent packaging constraints at affordable cost

Vacuum electronics for the 21st century

The development of a new three-dimensional electron gun and collector design tool is reported. This new simulation code has been designed to address the shortcomings of current beam optics simulation and modeling tools used for vacuum electron devices, ion sources, and charged-particle transport. The design tool specifically targets problem classes including gridded-guns, sheet-beam guns, multibeam devices, and anisotropic collectors, with a focus on improved physics models. The code includes both structured and unstructured grid systems for meshing flexibility. A new method for accurate particle tracking through the mesh is discussed. In the area of particle emission, new models for thermionic beam representation are included that support primary emission and secondary emission. Also discussed are new methods for temperature-limited and space-charge-limited (Child's law) emission, including the Longo-Vaughn formulation. A new secondary emission model is presented that captures true secondaries and the full range rediffused electrons. A description of the MICHELLE code is presented.

The MICHELLE three-dimensional electron gun and collector modeling tool: theory and design

A new 3D finite-element gun and collector modeling code, MICHELLE, is under development at SAIC in collaboration with industrial partners and national laboratories. This development program has been designed specifically to address the shortcomings of current beam optics simulation and modeling tools for vacuum electron devices. The program specifically targets problem classes including gridded-guns, sheet-beam guns, multi-beam devices, and anisotropic collectors. In particular, although there are 3D gun codes that exist today, their ability to address fine scale features is somewhat limited in 3D due to disparate length scales found in certain classes of devices. Additionally, features like advanced emission models, including thermionic Child's law and comprehensive secondary emission models also need attention for detailed modeling, and are included in the code. As part of this new effort, an algorithmic representation of a comprehensive model of secondary emission is being developed for this computational tool in order to achieve an accurate beam collection design capability. The basic physics model in the code is based on the equilibrium steady state application of the electrostatic PIC approximation employing both hexahedral and tetrahedral grid systems.

The new 3D electron gun and collector modeling tool: MICHELLE

The MICHELLE code is a new Finite-Element (FE) two-dimensional (2D) and three-dimensional (3D) electrostatic particle-in-cell (PIC) code that has been designed to address the recent beam optics modeling and simulation requirements for vacuum electron devices, ion sources, and charged-particle transport. Problem classes specifically targeted include depressed collectors, gridded-guns, multi-beam guns and sheet-beam guns. The focus of the development program is to combine modern finite-element techniques with improved physics models. The code employs a conformal mesh, including both structured and unstructured mesh architectures for meshing flexibility, along with a new method for accurate, efficient particle tracking. New particle emission models for thermionic beam representation are included that support primary emission, and secondary emission is handled with an advanced model. This presentation focuses on two significant advances to MICHELLE over the past year; hybrid structured/unstructured mesh support, and a time-domain electrostatic algorithm.

Recent advances in the MICHELLE 2D/3D electron gun and collector modeling code

The focus of the development program is to combine modern finite element techniques with improved physics models. The code employs a conformal mesh, including both structured and unstructured mesh architectures for meshing flexibility, along with a new method for accurate, efficient particle tracking. New particle emission models for thermionic beam representation are included that support primary emission, and secondary emission is handled with an advanced model.

Application of the 2D/3D MICHELLE code to electron gun and collector modeling

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

N. Dionne

Author Tools

Chat about Author

Papers

The MICHELLE three-dimensional electron gun and collector modeling tool: theory and design

The new 3D electron gun and collector modeling tool: MICHELLE

Recent advances in the MICHELLE 2D/3D electron gun and collector modeling code

Application of the 2D/3D MICHELLE code to electron gun and collector modeling