Active refrigeration of optoelectronic components through the use of thin film solid state coolers based on III-V materials is proposed and investigated. Enhanced cooling power comparing to the thermoelectric effect of the bulk material is achieved through thermionic emission of hot electrons over a heterostructure barrier layer. It is shown that these heterostructures can be monolithically int...

A theory for the single-channel hollow cathode (SCHC) that includes the relevant physical processes and predicts the operating parameters is presented. A SCHC consists of a cylindrical channel approximately ten diameters in length through which a working gas (taken as lithium vapor here) flows and exits as a plasma. A high current (1-100 A) is conducted into the channel by the plasma and to the...

Abstract A novel two-dimensional particle-in-cell code, named DESPICCO and developed at CNR-ISTP, is capable of simulating the thin plasma layer several millimeters, adjacent to divertor tiles a Tokamak fusion reactor. Here, kinetic effects non-neutral physics in Debye sheath can be self-consistently captured by Particle-in-Cell approach. The code firstly benchmarked against literature one-dime...

Since the discovery of X-rays over a century ago the techniques applied to the engineering of X-ray sources have remained relatively unchanged. From the inception of thermionic electron sources, which, due to simplicity of fabrication, remain central to almost all X-ray applications, there have been few fundamental technological advances. However, with the emergence of ever more demanding medic...

A detailed theory of nonisothermal electron transport perpendicular to multilayer superlattice structures is presented. The current–voltage (I – V) characteristics and the cooling power density are calculated using Fermi–Dirac statistics, density-of-states for a finite quantum well and the quantum mechanical reflection coefficient. The resulting equations are valid in a wide range of temperatur...

An analytical model which matches thermionic-emission-diffusion of holes across the emitter-base heterojunction with drift-diffusion transport across a graded base has been developed and used to examine the performance capabilities of InP-based Pnp heterojunction bipolar transistors ~HBTs!. Hole drift-diffusion across the emitter-base space charge region is shown to be of comparable importance ...

Global climate imperatives require a worldwide shift away from greenhouse gasemitting activities such as fossil fuel combustion. Concentrated solar thermal installations are particularly appealing as they can store a fraction of their power in the form of heat to provide baseload power, yet current conversion efficiencies prevent them from reaching competitive market prices. One extremely promi...