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In this work, an algorithm for coupling external circuit elements to electromagnetic (EM) particle-in-cell (PIC) simulations is developed. The circuit equation including an external voltage or current source, resistance, inductance, capacitance, and a dynamic load is solved simultaneously with the EM PIC updaters through an instant measured voltage across the system to obtain the supplied current...
This work introduces a conformal finite difference time domain (CFDTD) particle-in-cell (PIC) method with an improved field emission algorithm to accurately and efficiently study field emission devices. The CFDTD method is based on the Dey-Mittra algorithm or cut-cell algorithm, as implemented in the Vorpal code. For the field emission algorithm, we employ the elliptic function v(y) found by Forbes...
This work introduces a conformal finite difference time domain (CFDTD) particle-in-cell (PIC) method with an improved field emission algorithm to accurately and efficiently study field emission devices. The CFDTD method is based on the Dey-Mittra algorithm or cut-cell algorithm, as implemented in the Vorpal code. For the field emission algorithm, we employ the elliptic function v(y) found by Forbes...
In this work, an algorithm for coupling external circuit elements to EM PIC simulations is developed. The circuit equation including an external voltage or current source, resistance, inductance, capacitance, and a dynamic load is solved simultaneously with the EM PIC updaters through an instant measured voltage V across the system to obtain the supplied current I for feeding into the system. This...
In this work, a self-consistent general thermal field (GTF) emission model is formulated and the space charge effect on the original GTF equation developed by Jensen at NRL is studied analytically. We have also implemented the GTF algorithm in VORPAL, a conformal finite-difference timedomain (CFDTD) particle-in-cell (PIC) code. This analytic model could serve as a benchmark standard for the GTF CFDTD...
In general, the operating characteristics of RF vacuum electronic or plasma devices are affected by the power supply, e.g., a pushing effect on the oscillating frequency of a magnetron by a supplied anode current. The external impedance connected to the system under study should be included in the electromagnetic (EM) particle-in-cell (PIC) simulations especially when the system is in a transient...
In this work, a self-consistent general thermal field (GTF) emission model is formulated and the space charge effect on the original GTF equation developed by Jensen is studied analytically. We have also implemented the GTF algorithm in VORPAL, a conformal finite-difference time-domain (CFDTD) particle-in-cell (PIC) code. This analytic model could serve as a benchmark standard for the GTF CFDTD PIC...
Influence of ion effects on a space charge limited field emission flow has been studied systematically, by employing both analytical and numerical approaches. The analytic calculations are carried out self-consistently to yield the steady states of the bipolar flow. It is found that the field emission currents in the presence of saturated ion currents can be enhanced to be nearly 1.8, 1.5, and 1.4...
We propose a new fitting model for better characterizing field emitters such as a field emission array (FEA) that may be operated at high current density. In this improved model, we employ both effective work function and effective enhancement factor approximations. The experimental data can be fitted perfectly and therefore the discrepancy between the experimental results of FEA at high current density...
Summary form only given. This work introduces a conformal finite-difference time domain (CFDTD) particle-in-cell (PIC) method with improved field emission algorithms to accurately and efficiently study field emission devices. The CFDTD method is based on the Dey-Mittra algorithm or cut-cell algorithm, as implemented in the VORPAL code. Locally distorted cells with edges tangential to the metallic...
The feasibility of designing a multistage depressed collector using conformal finite-difference time-domain particle-in-cell simulations has been studied. A feedback mechanism is implemented to provide stable time-dependent voltages for each stage of the depressed collector. An arbitrary space-time dependent spent beam distribution can be given in our time-domain simulations. We demonstrate the design...
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