RESUMO
This paper gives a brief resume of the numerical work carried out over the past decade at the Electricity Utilisation Group usingfinite elements for the characterization of RF and microwave heating systems. Maxwell's equations are solved in 3D while for coronas the Poisson's and particle continuity equations are solved in 2D. In addition work on modeling thin films and the use of parallel computing describes the latest work to emanate from the group.
Assuntos
Desenho de Equipamento/métodos , Análise de Falha de Equipamento/métodos , Análise de Elementos Finitos , Calefação/métodos , Micro-Ondas , Modelos Teóricos , Análise Numérica Assistida por Computador , Ondas de Rádio , Simulação por Computador , Desenho Assistido por Computador , InglaterraRESUMO
The precursor of arcs in radio frequency heating systems, namely corona discharges, are examined numerically in this paper, using the finite element-flux corrected transport technique. A point-plane configuration is used as a first approximation for a radio frequency applicator and the effects of the operating frequency and pressure on the current output, charge densities, corona onset voltage and light output are investigated. It was found that an increase in the operating frequency around the radio frequency part of the spectrum, resulted in an increase in the corona onset voltage, which accounts for the less arc-prone behavior of microwave systems. Also, a decrease in the pressure resulted in a reduction of the corona onset voltage, and thus the increased possibility of arc formation in radio frequency systems operating under vacuum conditions.
Assuntos
Temperatura Alta , Modelos Teóricos , Ondas de Rádio , LuzRESUMO
This paper describes a new self-resonating switch-mode power-supply for driving CW magnetrons, based on the Boucherot effect. A detailed circuit analysis is given and its performance is evaluated for an 800 W/2450 MHz magnetron, whilst work at high power driving a magnetron up to 40 kW is reported. A comparison of the supply with the conventional power-supply used in microwave ovens is made and the principal features of the new design are found to be: low energy dissipation under short-circuit conditions, low ripple current and voltage waveforms that result in more precise control in the range 20-100% of rated power, high efficiencies and small size and weight.
