Power Loss Mechanisms Research Articles

Quantitative analyses of power loss mechanisms in semiconductor devices by thermal wave calorimetry

Photothermal and electrothermal measurements are used as a calorimetric method to study power dissipation in semiconductor devices as a function of applied bias. We have developed a model that allows a quantitative determination of the contributions due to the major heat-generating mechanisms which are responsible for conversion losses in different types of illuminated and non-illuminated photovoltaic cells and laser diodes.

Power loss mechanisms in radio frequency dry etching systems

The relation between the total radio frequency (rf) generator output power and the power that is actually dissipated in the plasma in rf dry etching systems was investigated. Power loss processes are described, their relation with the construction of the etch system is demonstrated, and their influence on the discharge is discussed. A method to estimate the power losses occurring in the etch system is described. For three different dry etching systems it is demonstrated that the stray capacitance of the system plays an important role in the power loss processes. In asymmetrical systems the dc self-bias voltage is shown to be a reliable parameter in determining the actual power dissipated in the plasma.

Correlation of acoustically detected thermal waves with injected and photogenerated currents in a photovoltaic cell

Acoustic detection of thermal waves emanating from a photovoltaic cell are employed to quantitatively distinguish between two power dissipation mechanisms, namely, space-charge thermalization of photogenerated carriers and recombination of injected carriers in the base region. The method can aid in quantitative calorimetric investigations of power-loss mechanisms in photovoltaic devices.

Fuel ion and alpha -particle excited impurity radiation in fusion plasmas

The rate of collisional excitation of plasma impurities by fuel ions and alpha -particles has been estimated. It is shown that the line radiation caused by such excitations can be an important power loss mechanism in fusion plasmas. The possibility of relative line intensity measurements of fuel ion temperature is also discussed.

Perspectives in magnetics: Italy

A review is given of fundamental research in magnetics pursued in Italian universities and laboratories of Consiglio Nazionale delle Ricerche. The main topics covered are in the field of soft materials, hard materials and garnets. The electronic structure of metals is investigated by polarized neutron diffraction, while studies of domain wall motion provide the basis for fully understanding power loss processes and mechanisms. Work on amorphous magnetism has focused in particular on the study of short range order in these materials. Most fundamental research on hard materials is directed toward permanent magnet applications, microwave devices and magnetic recording. Magnetization processes are a major subject of investigation in these materials, with applications both to hexagonal ferrites and rare earth-3d metal compounds. The crystal chemistry of garnets is being pursued by carrying out a variety of metal substitutions and studying site occupancies and valence states in both bulk materials and LPE films. The static and dynamic properties of domains are also investigated for display and memory applications in addition to microwave properties and materials.

Thermal Stability of Pure and Catalyzed D-D Fusion Reactor Plasmas

The thermal stabilities of the D-D fusion reactor plasmas operating on the pure- deuterium and the catalyzed-deuterium cycles have been analyzed by the first-order perturbation method in order to make clear the steady-state operating conditions. When the constant or trapped-ion mode scaling of the confinement-time is used, the critical temperature of the self-heated plasma lies in the vicinity of the minimum point for the confinement parameter nτ. Bohm scaling gives the lowest value for the critical temperature, while neo-classical scaling does the highest one. With increasing fuel injection energy, the growth rate of the instability at low temperature decreases, whereas it does not always decreases at high temperature. In the D-D fusion plasma, the subsidiary reaction 3He(d, p)4 He makes dominant contribution to the plasma heating and the instability at low temperature. The cyclotron radiation, the dominant power loss mechanism at high temperature, plays a significant role in determining the critical temperatures. Calculations neglecting the cyclotron radiation yield the inadequate, considerably higher values for them. The validity of the above results has been confirmed by the non-linear dynamic simulations.

Thermal stability of pure and catalyzed D-D fusion reactor plasmas.

The thermal stabilities of the D-D fusion reactor plasmas operating on the pure- deuterium and the catalyzed-deuterium cycles have been analyzed by the first-order perturbation method in order to make clear the steady-state operating conditions. When the constant or trapped-ion mode scaling of the confinement-time is used, the critical temperature of the self-heated plasma lies in the vicinity of the minimum point for the confinement parameter nτ. Bohm scaling gives the lowest value for the critical temperature, while neo-classical scaling does the highest one. With increasing fuel injection energy, the growth rate of the instability at low temperature decreases, whereas it does not always decreases at high temperature. In the D-D fusion plasma, the subsidiary reaction 3He(d, p)4 He makes dominant contribution to the plasma heating and the instability at low temperature. The cyclotron radiation, the dominant power loss mechanism at high temperature, plays a significant role in determining the critical tem...

Measurement of Power Transfer Efficiency from Microwave Field to Plasma under ECR Condition

Microwave power absorption is estimated directly in an ECR helium plasma by measuring the power loss from the plasma by the use of copper calorimeters. More than 70% of microwave power is absorbed by the plasma. Power loss mechanisms of the plasma are also examined.

Anode Phenomena in High-Current Accelerators

Quasi-steady MPD accelerators current conduction and power loss mechanism investigation through local anode fall voltage and current density measurements at different arc current levels

Possible sources of residual power loss in R.F. superconducting cavities

The residual power loss in rf superconducting cavities has not been well understood. Various power loss sources are considered and their dependence on frequency and temperature are compared with experimental results D One power loss mechanism stands out as the most likely source of the residual power loss, It has been observed that a residual power loss exists in rf superconducting resonant cavities at very low temperatures, contrary to theoretical expectations 192 which predict that for angular frequencies, w, below the quantum region, the power loss should vanish as the temperature, T , approaches 0 K. The good agreement between these theories and experiment at higher reduced temperatures suggests that they are valid, and that the discrepancy lies in the presence of a very low, non-superconducting power loss mechanism. The nature of this loss has not been well understood. This is due in part in the past to a lack of agreement between results reported by various investigators on nominally equivalent samples. However, the more recent experimental data in which the residual power loss has been further reduced tend to be more consistent. These results indicate that for very