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The electron multipliers gain is closely related to the secondary electron emission coefficient (SEE) of the emission layer materials. The SEE is closely related to the thickness of the emission layer. If the emission layer is thin, the low SEE causes the low gain of electron multipliers. If the emission layer is thick, the conductive layer can't timely supplement charge to the emission layer, the electronic amplifier gain is low too. The electron multipliers usually choose Al2O3 and MgO film as the emission layer because of the high SEE level. MgO easy deliquescence into Mg(OH)2 Mg2(OH)2CO3 and MgCO3 resulting in the lower SEE level. The SEE level of Al2O3 is lower than MgO, but Al2O3 is stable. We designed a spherical system for testing the SEE level of materials, and proposed to use low-energy secondary electrons instead of low-energy electron beam for neutralization to measuring the SEE level of Al2O3, MgO, MgO/Al2O3, Al2O3/MgO, and precisely control the film thickness by using atomic layer deposition. We propose to compare the SEE under the adjacent incident electrons energy to partition the SEE value of the material, and obtain four empirical formulas for the relationship between SEE and thickness. Since the main materials that cause the decrease in SEE are Mg2(OH)2CO3 and MgCO3, we use the C element atomic concentration measured by XPS to study the deliquescent depth of the material. We propose to use the concept of transition layer for SEE interpretation of multilayer materials. Through experiments and calculations, we put forward a new emission layer for electron multipliers, including 2–3 nm Al2O3 buffer layer, 5–9 nm MgO main-body layer, 1 nm Al2O3 protective layer or 0.3 nm Al2O3 enhancement layer. We prepared this emission layer to microchannel plate (MCP), which significantly improved the gain of MCP. We can also apply this new emission layer to channel electron multiplier and separate electron multiplier.

Low-temperature (∼eV) plasmas produced with cable guns or flash boards are the indispensable switching media for plasma opening switch (POS) used in pulsed power apparatus.1, 2 The determination of the plasma density is of interest to theoretical evaluation and experimental adjustment of the switch performance. Several diagnostic techniques have been developed to characterize the plasmas, including electrical probes,2, 3, 4 charge collectors,3, 4 microwave measurements,5 interferometry6, 7 and spectroscopy,8, 9 with charge collector being among simple and effective ones.

The specimen can be thought of as an electrical junction into which flows the beam current i B. The phenomena of backscattering of the beam electrons and secondary electron emission represent currents flowing out of the junction, i BSE and i SE, respectively. For a copper target with an incident beam energy of 20 keV, η is approximately 0.3 and δ is approximately 0.1, which accounts for 0.4, or 40%, of the beam current. The remaining beam current must flow from the specimen to ground to avoid the accumulation of charge in the junction (Thevenin’s current theorem). The balance of the currents is then given by $$ \eqalign{ & \sum {{i_{in}}} = \sum {{i_{out}}} \cr & {\rm{ }}{i_B} = {i_{BSE}} + {i_{SE}} + {i_{SC}}, \cr} $$ (15.1) where i SC is the specimen (or absorbed) current. For the example of copper, i SC = 0.6i B. Thus, even with a conducting specimen such as a metal, an electrical connection must be established to conduct this substantial current from the specimen to ground (typically the specimen stage is wellgrounded). Because all materials (except superconductors) have the property of electrical resistivity ρ, the specimen has a resistance R ( R = ρ l / A, where l is the length of the specimen and A is the cross section). The passage of the specimen current i SC through this resistance will cause a potential drop across the specimen, V = i SC R. For a metal, ρ is typically of the order of 10-6 ohm-cm, so that a specimen 1 cm thick with a crosssectional area of 1 cm2 will have a resistance of 10-6 ohm, and a beam current of 1 nA (10-9 A) will cause a negligible potential of about 10-15 V to develop across the specimen.

In this paper, we investigate the magnetic linear dichroism in the core-level photoemission spectra of the binary alloys CoxNi1−x and FexNi1-x /Cu(100).These epitaxial films have fcc structures, but very different magnetic behaviors. We show that the x-ray magnetic linear dichroism in photoemission (XMLD) signal tracks the magnetization in these alloys. Comparison with recent SQUID data provides a quantitative check and endorses the view that XMLD monitors the element-specific magnetometry.

Experimental information useful in improving and testing theoretical models of energy deposition and redistribution in particle-condensed phase media is discussed. An overview of information available from previous, and ongoing, studies of the electron emission from thin foils is presented and the need for doubly differential electron energy and angular distribution data stressed. Existing data are used to demonstrate that precisely known, and controllable, surface and bulk conditions of the condensed-phase media are required for experimental studies of this type. Work in progress and improvements planned for future studies at the Pacific Northwest Laboratory are outlined.

Realistic issues must be considered when solid electrical insulation is used in a low pressure environment. An important one from a reliability viewpoint is the physical basis for the electrical breakdown mechanisms in the gaseous medium, which inevitably accompanies the solid insulation. Whether the volume of the breakdown is macroscopic or microscopic, the Townsend mechanism can be dominant if the geometry and surface conditions are appropriate. In other cases, surface quenching or enhancements can modify the ionization growth.

Dust is an ubiquitous component of the cosmic plasma environment. It exists in the interstellar, circumstellar, interplanetary, circumplanetary and cometary environments. In each case it is immersed in a magnetized plasma and ultraviolet radiation environment. This leads the dust to be electrically charged and consequently coupled to the plasma by means of electrical and magnetic forces. Since this coupling becomes stronger as the grain size decreases, other things being equal, the recent in-situ detection of very small grains (VSGs with dimensions ≤ 100 A) in the environment of Halley’s comet and the inference of their existence in the interstellar medium2 provide further impetus to the study of dustplasma interactions in space.

A power grid tube is a device using the flow of free electrons in a vacuum to produce useful work.1 It has an emitting surface (the cathode), one or more grids that control the flow of electrons, and an element that collects the electrons (the anode). Power tubes can be separated into groups according to the number of electrodes (grids) they contain. The physical shape and location of the grids relative to the plate and cathode are the main factors that determine the amplifiication factor (µ) and other parameters of the device (see Section 3.2.5). The physical size and types of material used to construct the individual elements determine the power capability of the tube. A wide variety of tube designs are available to commercial and industrial users. By far the most common are triodes and tetrodes.

Charge phenomena occur in a wide variety of insulator materials when they are subject to various types of radiation. The goal of the present paper is to analyze these effects in order to try to elucidate them. For this goal, first the physical properties that insulators have in common are indicated. Next, based on the electrostatic, electrokinetic and secondary emission properties of insulators under irradiation, some explanations of the macroscopic effects of charging are given. The full description of these effects, using the electrostatic approach, requires the knowledge of the microscopic trapping mechanisms of charges; some of these mechanisms are suggested. This approach invalidates the former one based on the total electron yield curve. At last, various practical consequences are indicated or suggested.

The multiple electron emission from a thin (∼ 50 A) carbon foil has been measured for impacting primary H(H +), He, O, S — atoms with energies in the range of 10–200 keV. The absolute probabilities P k, P k′, P kk′ of the emission of k, k′(= 0, 1…) numbers ot electrons in forward (k), and/or backward (k′) direction from the foil have been derived. Using the Monte Carlo approach the processes of internal secondary electron production and transport were simulated. The observed SEE features were successfully reproduced in computations. Thus, the key values of the main processes which determine the peculiarities of heavy particle-induced electron emission from solids can be extracted from their simulations.

This subject covers a wide scientific field and has a long history—a number of investigations have been reported, and excellent textbooks and review papers have been published. This Chapter restricts the field of coverage to topics that are directly related to EBT, considering both fundamental physical and experimental aspects.

Ion-induced electron emission (IIEE) is a common phenomena which has been studied for many years. IIEE occurs when an energetic (about 10 keV/amu or greater) incident ion strikes a target material. This process is often called kinetic emission because kinetic energy is transferred from the incident ion to the constituents of the target via primary and secondary ionizing collisions. Experimental reviews of IIEE have been written by several authors in recent years (Baragiola, 1979a; Benazeth, 1982; Krebs, 1983; Hasselkamp, 1988; Brusilovsky, 1990; Hofer, 1990) and comprehensive theoretical articles also serve as good reviews (Sigmund and Tougaard, 1981; Bindi et al, 1987; Schou, 1988).

A swift projectile ion travelling in solid targets loses its energy through the excitation of electrons and plasmons. The charge distribution of the projectile ion itself comes close to the state of equilibrium through the charge exchange process with target atoms. Primary electrons produced in the direct ionization of target atoms by the projectile ion give birth to “secondary” electrons through a cascade process. Plasmons also decay into electrons [1]. A part of these electrons diffuse to the surface, overcome the surface potential, and escape from the surface. They are generally called “secondary electrons”, whose energy is mostly below ∼10 eV. The investigation of secondary electrons has a very long history and many review articles have been reported [2] [3]. The parameters observed in the secondary electron emission have been usually an average number, the energy distribution the angular distribution, etc.

Secondary electron emission (SEE) from solids, induced by X-rays and charged particles (electrons, ions), is a rather complex process. In a simplified description it can be divided into three independent stages: 1) production of secondary electrons by the primary radiation; 2) transport of secondary electrons in the solid towards the exit surface; 3) escape through the surface. All three stages involve processes which occur inside the solid and thus require, for their exact mathematical representation, the solution of a many-body quantum mechanical problem. Consequently semi-empirical theories and models were developed, which in general explain the main features of the SEE. During the last few years several reviews of SEE have been published1,2,3. It was shown that simple models1 may be used to reproduce the secondary electron yields and other integral characteristics of the process, for nearlyfree-electron metals. For noble and transition metals, semiconductors and insulators the simple semi-empirical models are not as successful. It was also shown2,3 that by using microscopic approaches for the basic interaction processes in the models of SEE they can be improved and may be used to calculate, for example, the energy spectra of the secondary electrons.

The Linear Energy Transfer (LET) concept is widely used in the context of Single Event Phenomena (SEP) in electronic devices induced by energetic heavy particles and protons in space missions. Very recently several experimental results have shown that the LET concept may not be adequate for a quantitative evaluation of a variety of SEP. Stapor et al.1 showed that different charge collection values in specially designed electronic devices were obtained for ions having the same LET but different energies. In two recent conferences E. Stassinopoulos2 gave a critical analysis for the validity of the LET concept in SEP while P. Sigmund discussed the relevance of the LET concept for secondary electron emission. There are also some indications of the failure of using LET as a measure in radiobiological investigations.

Rare gas solids (RGS) are good model systems to study ionization effects in insulators. Their electronic states are relatively well known[l]; they are monoatomic and bound by weak Van der Waals forces which allow them to be treated as dense gases with generally negligible chemical changes. The interaction of ionizing radiation with RGS produces lattice damage and desorption by the conversion of energy deposited as electronic excitation into kinetic energy. This conversion occurs by transitions involving repulsive potential energy curves and is generally known as desorption induced by electronic transition (DIET). We are studying the DIET mechanism in solid argon as described by Johnson and Inokuti[2], which also accounts for the bright luminescence observed during bombardment with ionizing particles. Previous studies have correlated sputter yields with luminescence yields in solid argon excited by MeV ions [3], low energy electrons[4], and photons[5, 6]. In order to determine the importance of this DIET mechanism in the decay pathways of electronic excitation, however, absolute correlation must be made. Furthermore, because this mechanism begins with an ionization event, the secondary electron emission processes during bombardment must also be understood and accounted for by any model for desorption and luminescence. In this paper we look at the beginning of this DIET mechanism by focusing on the secondary electron emission from bombarded solid argon.

We explain the de-excitation processes of the optically excited states of the F centers in alkali halides through the observation of the resonant secondary emission (RSE). Here, the RSE occurs successively as resonant Raman scattering, hot luminescence, and ordinary luminescence. By studying carefully the RSE and the transient effects of ultra-fast emission in de-excitation, we explain the dynamical processes of lattice relaxation within a strong interaction scheme of lattice and electron excited optically. We also show specific evidences of de-excitation caused by two-photon absorption of F centers in KC1 with a Nd:YAG laser excitation. Finally, magneto-optical processes in the optical pumping process of the F center are discussed.

Within the last two years matrix assisted laser desorption mass spectrometry of high mass organic molecules has rapidly evolved. The range of useful matrices has been widely enlarged [1] and the demonstrated detectability now covers proteins (up to several hundred kDa), polynucleotides including large DNA fragments (see paper of P. Williams, this volume), glycoproteins and polysaccharides. The notion that this technique is restricted to UV-lasers has recently become historical after Hillenkamp et al. [2] have demonstrated infrared lasers (Er:YAG, CO2) to be as effective in high mass ion production as UV-lasers.

Secondary electrons (SE) from ion bombardment of solids are messengers of the physical processes occurring during the interaction of swift ions (vP > vB) with condensed matter [1], In particular, experimental studies of doubly differential SE spectra d2n/dEdΩ in forward direction (observation angle ϴ=0°) induced by ion penetration of thin foils yield information on such important phenomena as low energy “true” SE (E < 10 eV), electrons from the decay of plasmons (E < 30 eV), convoy electrons (CE, ve = VP) and high-energy binary encounter electrons (ve= 2 vP) [2]. Moreover, characteristic target Auger electrons can be observed in SE spectra.