In this paper, we have studied the nonlinear performance and modeled the junction-less microring modulator (JL-MRM) designed on the standard silicon-on-insulator (SOI) platform. The JL-MRM utilizes ...the electrostatic doping effect to achieve the free carrier plasma dispersion effect in a silicon waveguide. A compact voltage-dependent steady-state model is analytically derived for JL-MRM. Using the compact steady-state model, closed-form expressions for the on–off extinction ratio (ER), optical modulation amplitude (OMA), and the quality of resonance (Q-factor) are also presented. We have also analyzed the nonlinear and chirp performance of JL-MRM. A small signal model for the MRM is also analyzed. The proposed device is simulated using commercially available TCAD and mode solver tools. Simulation results show that for a JL-MRM with 8.75 μm radius, the on–off ER and insertion loss (IL) are 20.5 dB and 1.98 dB, respectively. The estimated Q-value for MRM is approximately 11,630. From the proposed small signal model, the estimated 3-dB bandwidth, chirp parameter, and Q-value are found to be 28.29 GHz, -0.19, and 9979, respectively. From the nonlinear analysis, we also found that the proposed MRM for the input power level of 0 dBm offers approximately 82.15 dB.Hz1/2 and 109.87 dB.Hz2/3 of spurious free dynamic range (SFDR) for second harmonic and third harmonic distortions, respectively.
This paper is related to the study of the formation conditions and dynamics of self-sustained plasma-beam discharge at high energy density in the plasma of multiply ionized atoms. The efficiency of ...energy input into the discharge is shown by using a high-current pulsed plasma diode of low pressure. Based on the original calculation method, the dynamics of active voltage and active power inputted into the discharge are given. In such a system, the level of inputted active power can reach the value of 100 MW at the initial stored energy of 140 J. It is pointed out that the main mechanism of energy input into the discharge is a double electric layer of the space charge that is formed in the discharge gap. The intense electron beam accelerates in the double layer and heats the plasma to a high temperature in a short period of time. By controlling the arrangement of double-layer formation, one can input the energy locally into a certain discharge region. The distinctive features of the double-layer formation near the high-voltage electrode with a limited working surface for the even and odd half periods of the discharge current are indicated. The distribution of space potential in the discharge gap confirms that the double-layer formation is the result of not only the current instability but also the discharge transition to a new form of the self-sustained electric discharge in gas environment.
Cast iron is relatively cheap and highly machinable and is thus used for various mechanical parts. However, cast iron (H2 grade) is a high-carbon steel that shows cracks or craters owing to the ...martensitic transformation during conventional surface heat treatments. In this study, we investigated electron-beam (e-beam)-based direct preheating for preventing the formation of craters and cracks during the heat treatment of cast iron using a plasma diode e-beam. Scanning electron microscopy, X-ray diffraction analysis, energy-dispersive X-ray spectroscopy, and hardness measurements were performed to elucidate the crater and crack formation mechanism. Craters were formed within the graphite phase, owing to the low-melting-point elements and compounds. It was also observed that crack and crater formation was correlated to the distortion of the primary gamma phase, based on a significant decrease in the d-spacings. The direct preheating process resulted in a lower degree of distortion of the gamma phase. As a result, we could achieve a hardness as high as 800 HV without cracks or craters in cast iron, which is a cheap material. Moreover, the results of potentiodynamic polarization tests showed that the corrosion resistance increased after the surface treatment, owing to the removal of the low-melting-point impurities and grain refinement.
Electron beam cathodes have been used in various fields such as microscopy, X-ray tubes, welding, and surface modification. Generally, cathodes use metals with lower work function, higher thermal ...resistance, lower poisoning effects of gases, etc. LaB
6
, tungsten, and tantalum have normally been used as cathode materials with special materials coated if required. This study investigated the high-voltage plasma diode cathode for surface modifications of metal products such as polishing, hardening and heat treatment. The most fascinating features of this cathode are the high voltage and current that can be obtained at a low vacuum of a few mTorr. However, it is difficult to control the emission current to attain a steady state and to obtain higher brightness than that achieved using a thermal cathode. We studied the emission characteristics in terms of cathode and anode design parameters such as anode distance and cathode shape. Additionally, changes of emission characteristics are discussed in terms of the type of gas, pressure parameter, etc. using the emission resistance, effective breakdown voltage, and brightness. Finally, by measuring the change in surface roughness using the emitted electron beams, we found that the surface roughness values before the process were Ra=0.8 µm and Rz=5.4 µm, whereas those after the process were Ra=0.25 µm and Rz=2.3 µm. The electron beam polishing technology is eco-friendly and can minimize the emission of many harmful materials that arise when existing mechanical or electrochemical polishing technologies are used.
An analytical study of the plasma states in nonneutral plasma diodes and of their stability is presented for an arbitrary neutralization parameter
γ, including the Pierce (
γ=1) and the Bursian (
...γ=0) diode as special cases. Physically such a study is of interest, e.g. in the transport problem of an electron beam in spatially bounded electronic devices. Similarity transformations are obtained which connect equilibrium solutions of different
γ's. This implies that by simple transformations one can infer from equilibria of the generalized Pierce diode to equilibria of nonneutral diodes. The regimes with partial and total reflection of electrons are studied in detail for the first time. A classification of nonuniform solutions for these regions as well as for the regime without reflection is presented. The equivalence between the Eulerian and the Lagrangian formulation of the diode dynamics is proved, and both, the aperiodical and oscillatory eigenmodes of the generalized Pierce diode are examined. New bifurcation points in the branches of dispersion relations are discovered.
Linear Stability of a Plasma Diode Dobrowolny, M; Engelmann, F; Sestero, A
Zeitschrift für Naturforschung. A, A journal of physical sciences,
8/1969, Letnik:
24, Številka:
8
Journal Article
Recenzirano
Odprti dostop
The stability of a plasma diode with respect to longitudinal oscillations is investigated. If there are free particles emitted by the electrodes, the perturbations do not have the same dynamics as ...they would in an infinite plasma, contrary to the case where only particles trapped in the diode are present. This can be interpreted as due to a coupling of plane waves of different wave lengths, introduced by the boundary conditions at the electrodes. The occurrence of resonant-particle effects, on the other hand, is subjected to precisely the same conditions as in an infinite plasma.
In this paper, we report a CMOS compatible novel penta-electrode charge-plasma diode-based optical electroabsorption modulator (EAM). The proposed integrated EAM is junctionless and employs ...electrostatic doping in the semiconductor to change its absorption coefficient. The proposed EAM has a vertical metal-insulator-semiconductor (MIS) and lateral metal-semiconductor (MS) junctions. Using this novel MIS-MS-based charge plasma diode, EAM with various lengths are designed on the standard 220-nm silicon-on-insulator (SOI) platform. The numerical simulations, using commercially available TCAD tools and mode solvers, are performed to estimate the performances of the proposed modulators. A couple of combinations of materials having different work functions are used as electrodes to realize this MIS-MS charge plasma diode and their performances are extensively studied. The results predict that 550 <inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula>-long EAM with electrodes made of palladium and aluminum offers ~ 3.4 dB of dynamic extinction ratio (ER). Approximately 8.1 dB of insertion loss (IL) will be introduced by the proposed EAM with a length of <inline-formula> <tex-math notation="LaTeX">550~\mu \text{m} </tex-math></inline-formula>. The proposed modulator is expected to provide a maximum of 30.3 GHz operating speed with 26.2 GHz of 3-dB electrooptic bandwidth. Also, the simulation result indicates that the maximum dynamic energy consumption for the proposed EAM is approximately 39.1 fJ/bit at 12.5-Gb/s data rate.
This study delves into the radiation properties of a reconfigurable antenna that integrates both traditional single-channel SPiN diodes and dual-channel compensating SPiN diodes as core elements. The ...dual-channel SPiN diode compensates for the attenuation of carrier concentration at the midpoint of the intrinsic region, resulting in a carrier concentration exceeding 10
18
cm
–3
. The aim is to explore novel configurations of solid-state plasma antennas that have the potential to significantly improve radiation performance. The reconfigurable antenna is capable of operating in two distinct modes, specifically a low-frequency mode and a high-frequency mode, depending on the conducting state of the diode array. Through graphical analysis, it was observed that two reconfigured modes were successfully achieved, with relative bandwidths exceeding 13%. The incorporation of dual-channel compensating SPiN diodes led to notable performance improvements, as evident from a substantial reduction in the S11 parameter. These enhancements can be attributed to the intensified concentration and more uniform distribution of the solid-state plasma achieved by the dual-channel compensating devices.
This study was undertaken for improving the corrosion resistance, hardness, and toughness of SKD11, using the developed plasma diode electron beam equipment (PD-Ebeam). The SKD11 in this study is 1.5 ...w.t.% high-carbon steel; however, X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) analysis results after the PD-Ebeam treatment reveal that almost the entire iron matrix underwent an austenite phase transformation (F.C.C. crystal structure). Thus, an attempt is made to improve the hardness, toughness, and corrosion resistance using a characteristic of the austenite steel. A hardness enhancement of up to 680 (H.V.) could be achieved through PD-Ebeam heat and ultrasonic impact treatments. Further, the gamma structure sustainability and non-carbide formation were confirmed through the XRD and TEM analysis results. In addition, the friction coefficient in a wear test, was found to be lesser than that of vacuum heat-treated material, owing to the ductility of the gamma phase. As a result, it achieved 18% friction reduction, 47% reduction of wear, and corrosion resistance of level of the stainless steel (SUS304) compared to general vacuum heat treatment.
