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Figure 7. Influence of OFA on O2 concentration at the furnace outlet of PK39-steam generator
References:
1. Aliarov B. Combustion of Ekibastuz coals at thermal power plants. Almaty, Gylym, 1996.
2. Askarova A., Heierle Y., Leithner R., Mueller H. CFD Code Florean for Industrial Boilers Simulations//Wseas transactions on heat and mass transfer, Issue 4, Volume 4, 2009, ISSN: 1790-5044. P. 98-107.
3. Askarova, A. S., Messerle, V. E., Ustimenko, A. B., Bolegenova, S. A., Maksimov, V. Yu. Numerical simulation of the coal combustion process initiated by a plasma source//Thermophysics and aeromechanics. - 2014. - Vol 21, issue 6. - P. 747-754.
4. Bolegenova, S. A., Maximov, V. Y., Bekmukhamet, A, Beketayeva, M. T. Gabitova, ZK., etc. Computational method for investigation of solid fuel combustion in combustion chambers of a heat power plant//High temperature. -2015. - Vol. 5, issue 5. - P. 751-757.
Vorotyntseva Irina, Candidate of Science, lecturer Moscow State University of Civil Engineering E-mail: tyncher@inbox.ru Martsenyuk Nataliya, Senior lecturer
Moscow State University of Civil Engineering E-mail: yury.kon@mail.ru
Autophase microwave-convertor with multiple energy input
Abstract: The article considers the two-section TWT with an autophase output section model. It presents the results of numerical modelling of the back conversation in autophase TWT at the multiple microwaves energy input. It has been revealed that the efficiency of the back conversation can be considerably increased by the choice of optimal low of the static potential profile change.
Keywords: numerical modeling, autophase section, microwave power, electron bunch, convertor.
The main mechanism of the autophase TWT work in much more, for example ten times more, than in a bunch
the direct operation is described enough in the article section. Given certain conditions electron bunches are
[1]. The interaction mechanism in the autophase de- taken by the running wave in its potential minimum and
vices is the following: a bunch electron beam is gun in drift with speed that equals phase speed of the wave,
the interaction space, where the resistive coupling is saving their stability. Shifting the bunch in the breaking
Section 10. Physics
phase of the field by the static electrical field the high level of the conversion from the energy of static field to the energy of the microwave can be reached. The reverse conversation can be efficiently carried out by changing the pulling field sign or shifting the bunch into the accelerate phase of the microwave field [2; 3].
In the article the reverse conversation operation is studied by the numerical modeling method and the common scheme of such operation is investigated too. According to this scheme the input signal has to be sufficient to form an electron bunch. The bunch section can be realized by several ways. It can be a segment of the TWT, for example. The significant microwave power is given to the autophase section enter. Due to the phasing methods the entering electron bunch stand on the bottom of the running wave potential well, and the shifting static field conditions the bunch pressure on the well wall from the accelerating field side. Such scheme presupposes the presence of the natural restrictions on the transformable microwave power and transformation efficiency.
The conditions of the transport of the extensive beam in the interaction space determine the enter power level. The upper bound of the microwave power, that transforming in a constant one, is determined by the conditions of the saving of the bunch and wave finite movement [4]:
|EJ kkKc
<
y 0 - u0
E ^ — the static field, E -the microwave field, q —
st ' 0 ' 1
the electron charge, ffl — frequency, K0 — the resistive coupling, v0 — drift velocity, u0 — group velocity of the wave.
The presence of the powerful transverse variable fields also promotes a decay of the electron bunch. The electron, leaving the bunch and escaping the potential well, will infinitely shift along the interaction space, taking the energy for an acceleration, and set on the breaking system. Both these phenomena decrease the conversation efficiency.
There is also a lower microwave power bound, where the autophase conversation stops. In case of a single microwave power input in the interaction space and its following conversation in the current power the potential well depth decreases along the interaction space. So the running wave field cannot hold the electron bunch in the given phase relationships. The shoaling of the potential well to the critical level occurs at the significant remnant enter microwave power values. As the
numerical calculation showed this remnant power value can reach 30% at one energy enter. To reduce it the breaking system with increasing resist coupling at the exit is necessary to make. But it is needed to account the changing of the breaking system dispersion which conditions the increasing difficulties in the phasing of the bunch and field.
To resolve this contradiction it was suggested to make several microwave power inputs in the exit part of the autophase TWT [5]. They allow to prolong the interaction space length, on which the condition of the electron bunch containment in the potential well of the running wave saves. The injection of the next microwave power can de technically carried out by using the directing device of communication, for example, like directional coupler. It is of interest to construct such a method of conversion control in which the additional enter microwave power and the bunch are in the optimal phase relationships. But the additional enter of the energy is situated on the mutually fixed distance, while depending on the regime parameter the necessity of additional microwave energy injection can be in the point before enter. These difficulties can be removed by the optimal selection of the electrical breaking field. The properties mentioned above condition the necessary of the model researches of the back conversion at the different parameter values. The researches carried out by the numerical analysis in 3-D model of the TWT, what was described in [6] first.
The plots of dimensionless amplitude of the high-frequency field in the autophase section are shown in Pic.1. At the points % = 2 and | = 3 the additional microwave power was inj ected and the back conversation process was lasted and the conversation efficiency was essentially increased. The generic plots are presented in Pic.2. Using them the static field parameters can be optimally matched in the interaction space between the second and the third additional energy injections at the different values of the breaking field at the autophase section start. The present dependence allows to optimally manage the back energy transformation at the fixed distance between energy injections.
The model studies allow to state that the introduced way of the energy conversation actually allows lasting the back transformation and constructing the effective convertor. The nonfulfillment of the autophase condition cannot prevent the bunch destruction. The analysis of the calculation results allows to make the following conclusions. At the transition from the grouping to the autophase section the resistive coupling jump has to be
0
rather large, according to the transition coefficient equals maintenance. The distance between microwave
100. The additional energy inject has to realize before power inject decreases while the autophase section
the capture breaking at the well grouping condition length increases. F
3
2
1
1 2 3 4 5 6 %
Pic. 1. The dependence of the nondimensional amplitude of the high-frequency field on autophase section length
— 1
4 '2 3
— 7 L 5
12 3$
Pic. 2. The dependence of the nondimensional intensity of the static field on autophase section length
References:
1. Белявский Е. Д. Условия устойчивости захваченных электромагнитной волной электронных сгустков в продольном статическом электрическом поле//Изв. вузов. Сер. Радиофизика. - 1983. - Т. 26, № 10. -С.1312-1314.
2. Режим захвата частиц синхронной волной как метод повышения к. п.д. приборов СВЧ/Н. С. Гинзбург, И. А. Манькин, А. С. Сергеев и др.//Релятивистская высокочастотная электроника. - Горький: ИПФ АН СССР, 1988. - С. 7-19.
3. Folkner A. Y. Novel travelling-wave energy convertor//IEE Proc., 1985. - Vol.132, № 1. - P. 1-4.
4. Bondarenko B. N., Vorotyntseva I. I. The numerical modeling of the autophase TWT in the intensification re-gime//Physics in Ukraine. Kiev, 1993. P. 28-30.
5. Воротынцева И. И. Динамические процессы в автофазной лампе бегущей волны (ЛБВ) в режиме обратного преобразования//Интернет-Вестник ВолгГАСУ 2012. № 3 (23). С. 9-12.
6. Vorotyntseva I., Martsenyuk N. Minimization of the numerical errors in the dynamic models of large particles//Austrian Journal of Technical and Natural Sciences. 2015. № 3-4. P. 55-58.
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