FIELD DESORPTION OF INTERCALATED CAESIUM ATOMS FROM GRAPHENE ON THE (100) IRIDIUM FACE

С помощью полевой десорбционной микроскопии исследована десорбция атомов цезия с квазисферической науглероженной поверхности монокристалла иридия. Получены полевые электронные и десорбционные изображения поверхности при образовании графена на грани (100) иридия. Полевые электронные изображения поверхности эмиттера до интеркалирования и после интеркалирования графена атомами цезия не изменяются. Электрическое поле стимулирует десорбцию атомов цезия из интеркалированного состояния, вследствие разрыва связей крайних атомов углерода с поверхностью грани (100) иридия. С помощью покадровой регистрации показана возможность наблюдения локализации дефектов графенового слоя на поверхности полевого эмиттера. Показано, что полевая десорбция атомов цезия из интеркалированного состояния начинается с дефектов графена расположенных по периметру островка графена. Обнаружено, что десорбционные центры могут располагаться не только по периметру графенового островка, но и в центральной его части в случае образования неупорядоченного графена. The desorption of caesium atoms from the quasi-spherical carbonized surface of an iridium single crystal was studied using the field desorption microscopy. Field electron and desorption images of the surface during the formation of graphene on the (100) iridium face are obtained. The field electron images of the emitter surface before intercalation and after intercalation of graphene with caesium atoms do not change. The electric field stimulates the desorption of caesium atoms from the intercalated state, due to the breaking of the bonds of the extreme carbon atoms with the surface of the face (100) of iridium. Using frame-by-frame recording, the possibility is shown of observing the localization of graphene layer defects on the surface of the field emitter. It is also shown that the field desorption of caesium atoms from the intercalated state begins with graphene defects located along the perimeter of the graphene island. It is found that desorption centers can be located not only along the perimeter of the graphene island, but also in its central part in the case of the disordered graphene formation.

Novelty Surface Coatings for Far Infrared Spectrum Black Body Radiators

Black body radiation sources are commonly used devices in areas related to thermal imaging and radiometry. They are the closest physical approximation of theoretical black body emitter derived from the Planck’s law. Majority of such devices are costly with restricted information about their production technology, including their emitter surface. A few relatively easily accessible coatings with potential application in such devices have been chosen and their emissivity measured. The paper presents measurements that provides information necessary to determine whether there are coatings viable for black body emitter or reference surface.

Application of an additional electrode for improving the emission properties of the lossless cathode-neutralizer for EPSPS

The article considers the advantages of application of an additional electrode — anode-collector in the design of a lossless cathode-neutralizer (LCN) for electrically powered spacecraft propulsion systems (EPSPS) (hall-effect thrusters and ion thrusters). The relevance of the work is due to the increased interest in the possibility of using lossless thermionic cathodes as cathodes-neutralizers (CN) of EPSPS. Based on the results of laboratory tests of the lossless cathode-neutralizer model conclusions are drawn about the effectiveness of the anode-collector in the design of the lossless cathode-neutralizer. The presence of the collector-anode allows for additional “stimulation” of the emitter by voltage intensifying the emitter activation process and increasing the emission current from the emitter surface by 2-2.3 times. The saved energy for emitter heating due to using an anode-collector is estimated. The basic concepts and recommendations for the development of the design of lossless cathode-neutralizer design are presented.

Математическое моделирование двумерной диодной системы с полевым эмиттером лезвийной формы

In this paper the calculation of the electrostatic potential distribution for a two-dimensional diode emission system with a blade-shaped field emitter on a plane substrate is presented. The anode is a plane parallel to the substrate. To calculate the potential distribution, the effect of the emitter is simulated as the effect of a charged line, so that the emitter surface is zero equipotential. To solve the boundary problem, the method of separation of variables in Cartesian coordinates is used. All geometrical sizes of the diode system are parameters of the problem.

Полевая десорбция цезия с рения

Desorption of cesium atoms from a rhenium point emitter in an electric field has been studied by method of field-desorption microscopy (FDM). Dependence of the desorbing field on degree of emitter surface coverage with Cs atoms is established. The heat of Cs-atom adsorption, which is dependent on the surface concentration of adsorbate and work function of the surface, is estimated in the framework of the model of mirror-image forces for field-induced desorption. Saturation of the rhenium emitter with carbon leads to changes in the character of desorption and in the distribution of desorption zones on the emitter surface.