Pierce Type Research Articles

New approach to greedy vector quantization

We extend some rate of convergence results of greedy quantization sequences already investigated in 2015. We show, for a more general class of distributions satisfying a certain control, that the quantization error of these sequences has an optimal rate of convergence and that the distortion mismatch property is satisfied. We will give some non-asymptotic Pierce type estimates. The recursive character of greedy vector quantization allows some improvements to the algorithm of computation of these sequences and the implementation of a recursive formula to quantization-based numerical integration. Furthermore, we establish further properties of sub-optimality of greedy quantization sequences.

Study of the subtyping machine of nominal subtyping with variance

This is a study of the computing power of the subtyping machine behind Kennedy and Pierce's nominal subtyping with variance. We depict the lattice of fragments of Kennedy and Pierce's type system and characterize their computing power in terms of regular, context-free, deterministic, and non-deterministic tree languages. Based on the theory, we present Treetop---a generator of C# implementations of subtyping machines. The software artifact constitutes the first feasible (yet POC) fluent API generator to support context-free API protocols in a decidable type system fragment.

Design of an Electron Gun for an 8 MW Peak, 30kW Average Power S-Band Klystron

High Power S-band pulsed klystrons with peak power greater than 6 MW are widely used as RF sources in particle accelerators. This paper presents an electron gun (pierce type) design for such a klystron with an output power of 8 MW peak and 30 kW average with its intended applications in accelerators for food processing. The targeted device is currently under design at CSIR-CEERI and will be developed later on. The results of electron gun simulation through computational codes like Trak, CST particle studio, and Opera are compared to find an optimum design for the electron gun to be fabricated for the klystron.

Messages of parents affection for children in the movie bulan terbelah di langit amerika

This study aims to explain how the message of peace and what peace messages are featured in the film. This type of research is qualitative. Researchers analyze the signs that appear in the drawings and dialogue using semiotic analysis of Charles Sander Pierce model, as well as classify in Pierce type of icons, indexes, and symbols. The result of this research is that to the filmmakers, researchers hope that every production of films should consider the interests of the wider community, not only about idealism alone should pay attention to the nature of the media itself, namely informative, educative, and also entertaining As modeled after the Bulan terbelah di Langit Amerika

Giant amplification in degenerate band edge slow-wave structures interacting with an electron beam

We propose a new amplification regime based on a synchronous operation of four degenerate electromagnetic (EM) modes in a slow-wave structure and the electron beam, referred to as super synchronization. These four EM modes arise in a Fabry-Pérot cavity when degenerate band edge (DBE) condition is satisfied. The modes interact constructively with the electron beam resulting in superior amplification. In particular, much larger gains are achieved for smaller beam currents compared to conventional structures based on synchronization with only a single EM mode. We demonstrate giant gain scaling with respect to the length of the slow-wave structure compared to conventional Pierce type single mode traveling wave tube amplifiers. We construct a coupled transmission line model for a loaded waveguide slow-wave structure exhibiting a DBE, and investigate the phenomenon of giant gain via super synchronization using the Pierce model generalized to multimode interaction.

Pierce gain analysis for sheet-beam multiple-circuits traveling-wave amplifiers

A pierce type analysis for multiple-circuits sheet-beam traveling wave amplifiers is presented. The introduced analysis effectively reduces the required time for the initial design and optimization procedure of these kinds of tubes. The one-dimensional linearized Pierce theory is extended to multiple circuits coupled to the sheet beam using equivalent circuit of slow-wave structures as well as dividing the sheet beam into many discrete beams, and then, the amplifier gain is calculated. Furthermore, this analysis is used to calculate the gain of two sheet-beam TWTs with single and double slow-wave structures, and the results are compared with those of particle-in-cell simulations. Good agreement between these results verifies the correctness and accuracy of the presented analysis.

Development of a C-Band 2.5-MW Peak Power Broadband Klystron Based on High Efficiency

This paper presents the design considerations, simulation results, and test results of a high-efficiency high-power broadband klystron. In the design of the entire tube, it is the key part to design the high-efficiency beam-wave interaction section, so this part is described in detail, including the frequencies, Q values, arrangement locations of buncher cavities, as well as transit angles of drift tubes, and so on. Meanwhile, the electron gun is designed as a typical Pierce type with a pencil beam, and the perveance and normalized radius of electron beam are set to 2.1 μP and 0.51, respectively, by considering requirements of the efficiency and bandwidth synthetically. What is more, the output window is designed based on high average power by symmetric pillbox window structure. The test results indicate that in the case of saturated drive and 5.1% relative bandwidth, the klystron can get a peak power of more than 2.5 MW, an efficiency of more than 40%, a gain of more than 49 dB, an average power of more than 2.5 kW, and output power flatness of less than 0.63 dB.

Constructive quantization: Approximation by empirical measures

Dans cet article, nous etudions l’approximation d’une mesure de probabilite $\mu$ sur $\mathbb{R}^{d}$ par sa mesure empirique $\hat{\mu}_{N}$, interpretee comme quantification aleatoire. Comme critere d’erreur, nous considerons une moyenne de metrique de Wasserstein d’ordre $p$. Dans le cas $2p<d$, nous etablissons des bornes superieures et inferieures ameliorees pour l’erreur, une formule haute resolution. De plus, nous donnons une estimation universelle a base de moments, nommeee estimation du type Pierce. En particulier, nous prouvons que, sous de faibles hypotheses, la quantification par des mesures empiriques est d’ordre optimal.

Recent Developments of Low-emittance Electron Gun for Accelerator

Recent developments of low-emittance electron guns for accelerator are reviewed. In the accelerator field, DC biased triode thermionic gun (Pierce type gun) has been widely used and is still conventional. On the other hand, because of strong demands on the high brightness electron beam by FEL and other advanced accelerator concepts based on linear accelerator, the low emittance beam generation becomes one of the most important issue in the accelerator science. The R&D effort is “accelerated” by two technological innovations, photo-cathode and RF gun. They made a large improvement on the beam emittance. After the explanations on the technical and physical aspects of the low emittance electron beam generation, advanced electron sources for accelerators are reviewed.

Contour-Mode AlN Resonator with High Coupling Factor

A micro electro mechanical systems (MEMS) type contour-mode resonator with a high coupling factor of several percent is proposed. The fabricated 60-MHz-band radial-extensional resonators using MEMS process technology of AlN film exhibited a high coupling factor of 2.8% and high Q values of 3000 at the series resonant frequency and 4000 at the parallel resonant frequency. We demonstrated a Pierce type oscillator using the radial-extensional resonators and achieved low power consumption and stable oscillation. These radial-extensional resonators were suitable for filter and oscillator applications because the figure of merit, defined as the ratio of the Q value and the capacitance ratio, was 71 at the series resonant frequency and 94 at the parallel resonant frequency, which were the highest values of the contour-mode AlN resonators.

Formula omitted]-dependence statistics for mutual and serial independence of categorical variables

The Möbius transformation of probability cells in a multi-way contingency table is used to partition the Pearson chi-square test of mutual independence into A-dependence statistics. A similar partition is proposed for a universal and consistent test of serial independence in a stationary sequence of a categorical variable. The partition proposed can be adapted whether using estimated or theoretical marginal probabilities. With the aim of detecting a dependence of high order in a long sequence, A-dependence terms of the partition measuring increasing lagged dependences can be combined in a Box–Pierce type test of serial independence. A real data analysis of a nucleotides sequence using the Box–Pierce type test is provided.

Thermal analysis of electron gun for travelling wave tubes

Thermal analysis of a pierce type electron gun using the FEM software ANSYS and its experimental validation are presented in this paper. Thermal analysis of the electron gun structure has been carried out to find out the effect of heater power on steady state temperature and warm-up time. The thermal drain of the supporting structure has also been analyzed for different materials. These results were experimentally verified in an electron gun. The experimental results closely match the ANSYS results.

Design and Development of Coaxial Convergent Electron Gun for Gain and Phase Matched Miniature Helix TWT

A Pierce type convergent electron gun with coaxial compact geometry has been designed and developed for a broadband gain and phase matched miniature helix Travelling Wave Tube. For the design of above gun, synthesis approach particularly for the estimation of anode hole aperture has been modified and used, which resulted in closer agreement with experimental value of the same parameter. A theoretical and experimental study regarding the effects of beam forming electrode (BFE) negative bias on beam optics has been discussed. Criticalities Involved in the development of such a compact miniature electron gun meeting the requirement of tube to tube gain and phase matching have been discussed along with the techniques to overcome the same.

A new approach for high power electron beam gun design using scaling rules

A method is presented to extrapolate the design of a currently exploited gun into a new family of similar guns with new preferable technological parameters, for example with higher electron beam power, accelerating voltage, electron brightness and so on. The method is based on the scaling theory of electron-optical devices (EOD). According to the theory only EOD with small space charge, i.e., with perveance G < 0.01 μP, can be size and/or voltage scaled. EOD containing relatively big space charge (G ≥ 0,01 μP), such as high energy Pierce type electron guns applied in thermal technological machines, generally cannot be scaled, because of their nonlinear space charge nature. Nevertheless, also in these cases a special procedure of scaling can be applied. The reason is that the electron charge distribution in the gun is not uniform. Near the anode the density of electron charge is much smaller than in the cathode region. The concept of high perveance electron gun designing using scaling rules is based on the idea to apply the scaling rules only to the anode zone of the gun. The procedure for scaling a low power 25 kV and 150 mA electron extract system with a cylindrical electron beam into a high power 75 kV and 150 mA electron extract system is described in this paper. An experimental investigation confirmed the good technological quality of a high voltage, high power gun constructed according to the above concept.

Experimental design of high energy electron gun by means of scaling rules

The possibility of the design of a new family of electron guns by means of scaling theory of electron-optical devices (EOD) is presented. According to the theory, EOD with a relatively big space charge, as in high energy Pierce type electron guns used in technological equipment, generally cannot be scaled, because of their nonlinear space charge nature. Therefore, the scaling rules are applied here only to the anode zone of the gun, where the electron beam perveance is small, and the cathode lens of gun with considerable space charge remains unchanged. The procedure for scaling a 25 kV and 150 mA gun with cylindrical electron beam into a high voltage 75 kV and 150 mA electron system is given. An experimental investigation proved the high technological quality of a high voltage gun constructed according to the above conception.

Amplification in Gyro-Travelling-Wave Tubes—Dispersion Relation and Gain-Bandwidth Characteristics

The interaction in a cylindrical waveguide, loaded with a thin hollow beam of electrons gyrating in helical paths to give a gyro-TWT configuration, is investigated. The beam perturbation is estimated by solving the relativistic Vlasov's equation and a dispersion relation describing the beam-wave interaction is obtained for an electron beam of zero guiding centre spread. The dispersion relation is interpreted following the Pierce type approach to a conventional TWT to obtain a gain equation of the well known form G = A+BCN. The influence of the basic parameters such as beam voltage, beam current, velocity pitch factor and DC magnetic flux density on the gain-frequency response is extensively investigated to find a trade-off between the gain and bandwidth. The results show that an increase in beam current improves the gain whereas at higher beam voltages one gets a flat gain-frequency response though at the cost of the gain. A high value of the velocity pitch factor gives a higher gain however at frequencie...

SPLEEM of Magnetic Surfaces and Layered Structures

Spin-polarized low-energy electron microscopy (SPLEEM) is a new approach to magnetic-surface imaging. Historically, it is an outgrowth of LEEM (low-energy electron microscopy), which has been successfully applied to the high-speed in situ imaging of microscopic surface structures under clean ultrahigh-vacuum (UHV) conditions. In terms of basic instrument design, in SPLEEM a spin-polarized electron source of the Pierce type replaces the LaB6 field-emission electron source used in all dedicated LEEM systems. A new, fully electrostatic version of LEEM has recently been developed, resulting in a more compact, flange-on-type instrument component, which can be integrated with standard UHV surface analytical systems. The main advantage of the new SPLEEM technique is an advanced electron-source design that allows the spin direction to be arbitrarily adjusted with respect to the sample surface (see the following).

XEBIST: simplified EBIS/EBIT without magnetic field

EBIS and EBIT usually need a longitudinal magnetic field to focus a high density electron beam along the ionisation region. An alternative to EBIT, which has a short trap length, is a device in which the electron beam is focused by convergent launching from the gun and inertia only. A carefully designed Pierce type electron gun produces a high current density region at the beam crossover, forming the ion trap. As obtained in welding guns, values of more than 10 3 A/cm 2 are possible at electron energies of 150 keV. As in any EBIS, the energy spread and the emittance can be given extremely small values by lengthening the extraction time, which is usually as short as 30 to 100 μs. This source therefore will have a special advantage for experiments with highly charged ions at low velocities. The device can be useful as an ion source (EBIS) as well as an ion trap (EBIT), therefore the new generic name EBIST (Electron Beam Ions Source and Trap) is being proposed. A prototype of an XEBIST (X for crossover) has been designed, constructed and tested. With a 20 mA electron beam at 3.5 keV and confinement times of about 50 ms ions like Ne 6+, Ar 10+, Kr 12+, and Xe 14+ have been obtained already (H. Thomae, dissertation, Fachbereich Physik der Universität Frankfurt am Main (1994) [1]). An upgrade program is underway to improve the residual gas pressure as well as the breakdown limitations in order to produce much higher charge states (at the time of writing 100 mA have been obtained at 10 keV).

Numerical solution of laplace equation in three dimensions for a pierce type electron gun

In this paper, as part of a three-dimensional ribbon beam gun design, Laplace equation is solved in 3D for the case of boundaries which can be represented as simple surfaces which are subjected to specified voltages. Curve fitting by the least squares method is used to characterize the accelerator electrode shape as an extension of the 1D laminar electron flow in a Pierce type electron gun. The method involves solution of governing equations by an iterative finite difference technique. Modification of the standard Leibmann procedure is used to greatly increase the rapidity of convergence. The technique of handling irregular boundary points is considered in detail.

A unified theory of the diocotron, cyclotron maser, and negative-mass instabilities

A small-signal theory is developed which simultaneously includes the diocotron, negative mass, and cyclotron maser effects. The simple analysis is performed using a Pierce type approach for an axis encircling electron beam inside a circular waveguide. Relativistic, nonrelativistic, synchronous, and nonsynchronous limits are considered to recover the individual instabilities. It is found that the diocotron and the negative mass/cyclotron maser effect strengthen each other. At voltages higher than a few kiloelectron volt the relativistic negative mass/ cyclotron maser effects become dominant. However, the threshold beam voltage, which appears in gyrotron literature, for the onset of the cyclotron maser instability is found absent when the diocotron effect is taken into account. The feasibility of building a low-voltage tube is explored.