1984 secondary electron emission characteristics of ion-textured

Fore

Moreover, the positive feedback between the ion current and the electron emission current can lead to instability of the plasma emission boundary and subsequent breakdown of the acceleration gap. In the case of large-cross-section electron beams generated in the fore-vacuum pressure range, the back-streaming ion flow greatly increases the non-uniformity of the beam current density distribution.

Comparative study of depth and lateral distributions of

Secondary Electron Emission from Rough-Textured Beryllium Surface under Oblique Incidence of Low-Energy Electrons Contrast-to-gradient method for the evaluation of image resolution taking account of random noise in scanning electron microscopy

NASA Technical Reports Server (NTRS)

Secondary electron emission characteristics of untreated and ion-textured titanium Experimentally determined values of true secondary electron emission and relative values of reflected primary electron yield are presented for untreated (simply machined) and ion-textured, high-purity titanium over ranges of primary electron beam energies and beam impingement angles.

Charging phenomena on insulating materials: Mechanisms and

206 Scanning Vol. 12,4 (1 990) Anode Cathode FIG 4 Electron cascade model for the explanation of surface flashover: a current, I,,, emitted at the cathode, is multiplied by the electron cascade effect to reach a value, Is:, which causes flashover. Is: should be dependent on I,,, on the secondary yield,

High

A NASA-sponsored research and development contract has been established with the Watkins-Johnson Company to fabricate high-efficiency 20-watt helical traveling wave tubes (TWTs) operating at 8.4 to 8.43 GHz. The TWTs employ dynamic velocity tapers (DVTs) and advanced multistage depressed collectors (MDCs) having electrodes with low secondary electron emission characteristics. The TWT designs

Characterization of Laser

the laser-plasma characteristics in addition to their applica-tions in ion implantation,1 ion surface cleaning and pattern-ing,1 secondary ion mass-spectrometry,2 extreme ultraviolet lithography,3 and for injection in electron cyclotron resonance ion sources and ion

NASA Technical Reports Server (NTRS)

Secondary electron emission characteristics of molybdenum-masked, ion-textured OFHC copper A method for producing a uniform, highly textured surface on oxygen-free, high conductivity (OFHC) copper by ion bombardment using sputtered molybdenum as a texture-inducing masking film was developed and used to provide samples for study.

Ion kinetics in Ar/H2 cold plasmas: the relevance of ArH+

2014/11/3The recent discovery of ArH + in the interstellar medium has awakened the interest in the chemistry of this ion. In this work, the ion-molecule kinetics of cold plasmas of Ar/H 2 is investigated in glow discharges spanning the whole range of [H 2]/([H 2]+[Ar]) proportions for two pressures, 1.5 and 8 Pa. Ion concentrations are determined by mass spectrometry, and electron temperatures and

Ion kinetics in Ar/H2 cold plasmas: the relevance of ArH+

2014/11/3The recent discovery of ArH + in the interstellar medium has awakened the interest in the chemistry of this ion. In this work, the ion-molecule kinetics of cold plasmas of Ar/H 2 is investigated in glow discharges spanning the whole range of [H 2]/([H 2]+[Ar]) proportions for two pressures, 1.5 and 8 Pa. Ion concentrations are determined by mass spectrometry, and electron temperatures and

Corpuscular diagnostics and processing methods applied

Special attention was focused on the ion-induced secondary electron emission problem and its influence on the accuracy of the measurements. Send article to Kindle To send this article to your Kindle, first ensure no-replycambridge is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon

Improvements in MDC and TWT overall efficiency

Ion-textured graphite was found to be particularly effective in minimizing the secondary electron emission losses. Experimental and analytical results, however, indicate that it is at least as important to provide a maximum amount of electrostatic suppression of secondary electrons by proper MDC design.

Glow discharge

A glow discharge is a plasma formed by the passage of electric current through a gas. It is often created by applying a voltage between two electrodes in a glass tube containing a low-pressure gas. When the voltage exceeds a value called the striking voltage, the gas ionization becomes self-sustaining, and the tube glows with a colored light.

MICROSCOPY SOCIETY OF AMERICA 2012 Ionoluminescence in the Helium Ion

Ionoluminescence in the Helium Ion Microscope Stuart A. Boden,1,* Thomas M.W. Franklin,2 Larry Scipioni,3 Darren M. Bagnall,1 and Harvey N. Rutt1 1Electronics and Computer Science, University of Southampton, Highfield, Southampton SO17 1BJ, UK 2Optoelectronics Research Centre, University of Southampton, Highfield, Southampton SO17 1BJ, UK

Modeling of the effect of field electron emission from the

2018/3/1It follows from this formula that an influence of the field electron emission from the substrate on the cathode effective secondary electron emission yield and consequently on the discharge characteristics is determined completely by parameter δ f, which is called].

Wide

The paper describes the operation and design specifics of wide-aperture accelerators based on non-self-maintained high-voltage glow discharge. Shown are the advantages of these accelerators over the conventional accelerators based on a number of longitudinal thermal emitters. The paper presents the main characteristics and parameters of accelerators developed at the Efremov Institute of

NASA Technical Reports Server (NTRS)

Beam impingement angle effects on secondary electron emission characteristics of textured pyrolytic graphite Experimentally determined values of true secondary electron emission and relative values of reflected primary electron yield for untreated and ion-textured pyrolytic graphite over a range of primary electron energy levels and electron beam impingement angles are presented.

Tokamak plasma diagnosis by electrical probes

Tokamak pJasma diagnosis by electrical probes 1597 60 40- 2 - +* 20 0 Reciprocating probe oTe (SOL) Target AT^ (wter div.) probes I oT, (inner div.) A - I I I I 0 0.5 1.0 1.5 2.0 2.5 3.0 -20,..-IJlp5.5 Figure 2. Langmuir probe characteristic recorded i in T10 showing low electron to ion saturation

Recommended Practice for Use of Emissive Probes in

2016/11/3[44] Schwager L. A., " Effects of Secondary and Thermionic Electron Emission on the Collector and Source Sheaths of a Finite Ion Temperature Plasma Using Kinetic Theory and Numerical Simulation," Physics of Fluids B, Vol. 5, No. 2, 1993, pp. 631–645. doi:

Secondary electron emission from reticulated cellular

An experimental and computational study of the secondary electron yield (SEY) of copper foam is presented. Ray-tracing Monte Carlo (MC) simulations, based on primary electron transport and interactions with the electron system in solid and foam-type copper, are

Origin and nature of the emissive sheath surrounding hot

2020/12/1With the knowledge of q surf and T e, the electron density at the sheath entrance can be calculated from (16) n e s.e. = q surf γ T e C s sin α.In the above; γ = 7 is used for the sheath heat transmission coefficient, C s = (T e + T i) ∕ m i is employed for the sound speed with T i = T e and m i = 2. 5 m H for the average ion mass in DT mixtures, α = 3. 2 and 3.7 is utilized for the

The Manchester (e,2e) Experimental Hardware page

The Manchester (e,2e) Experimental Hardware page prepared by Andrew Murray The Vacuum System. The (e,2e) spectrometer vacuum chamber (figure 1) is manufactured from 304 grade stainless steel, the construction being carried out by Vacuum Generators using a design of Jones, Read and Cvejanovic, full details of which may be found in T. Jones' Ph.D. thesis (University of Manchester (1984)).

US4910435A

A wide area electron gun in which an electron beam originates from secondary emission electrons emitted by a target bombarded by ions. A cylindrical main housing has a central region where the secondary emission target is located and auxiliary housings on opposed sides of the target, outside of the main housing, contain low temperature ion plasmas.

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