V. I. Kuznetsov

Cascaded space solar power system with high temperature Cs-Ba thermionic converter and AMTEC

The paper presents an innovative concept of a cascaded solar bimodal power system with a high temperature Cs-Ba thermionic converter (TEC) and Alkali Metal Thermal to Electric Converter (AMTEC). Cs-Ba thermionic technology appears to be an ideal candidate for a TEC-AMTEC cascade due to high optimum collector temperature of such a TEC. Results show that the cascade conversion efficiency in excess of 45% is feasible. The efficiency of the high temperature a Cs-Ba TEC-AMTEC cascade is also compared with that of a Cs-Ba TEC-thermoelectric cascade. A cascaded solar concentration system which provides both high temperature (Cs-Ba TEC) and low temperature (AMTEC) energy conversion stages with their own concentrator, receiver and heat exchanger, and its advantages for solar bimodal systems are also discussed. The paper shows that the use of the high temperature Cs-Ba TEC-AMTEC cascade would allow the development of a highly efficient, compact and light power as well as bimodal systems to address future civilian a...

Ultra‐High Temperature Thermionic System for Space Solar Power Applications

Theoretical and experimental investigations made to date at the Ioffe Physico‐technical Institute on ultra‐high temperature thermionic energy converter (TEC) have demonstrated the possibility of significantly increasing the efficiency of such a converter when operating in the Knudsen mode. In the arc mode of inevitable scattering losses make up about 50%. The TEC efficiency rises sharply when operating in high and ultra‐high emitter temperature range (2500 – 3000 K). As a result, it is possible, in principle, to fabricate a TEC with emitter temperature of 2500 – 2600 K and having an efficiency of about 25% and long life. If design and engineering problems are solved, such a TEC in combination with a solar concentrator can be used to serve as a spacecraft power system. It can be also used as a high temperature stage of a terrestrial solar power station. This paper presents some of the features of a Cs‐Ba high emitter temperature TEC and a conceptual design of a 5 kWe solar thermionic power system.

The transverse magnetic field effect on steady-state solutions of the Bursian diode

A study of steady-states of a planar vacuum diode driven by a cold electron beam (the Bursian diode) under an external transverse magnetic field is presented. The regime of no electrons turned around by a magnetic field only is under the consideration. The emitter electric field is evaluated as a characteristic function for the existence of solutions depending on the diode length, the applied voltage, and the magnetic field strength. At certain conditions, it is shown that a region of non-unique solutions exists in the Bursian diode when the magnetic field is absent. An expression for the maximum current transmitted through the diode is derived. The external magnetic field is put forth to control fast electronic switches based on the Bursian diode.

Bimodal solar system based on a ultra-high-temperature TEC

The paper considers an ecological, solar, bimodal system with ultra‐high temperature thermionic energy converter (TEC). The solar bimodal Space Electric Propulsion System (SEPS) characteristics are presented.

Stability analysis of steady state solutions of Bursian diode in presence of transverse magnetic field

The stability properties of the steady state solutions [Pramanik et al., Phys. Plasmas 22, 042110 (2015)] of a Bursian diode in presence of constant transverse magnetic field have been studied. Employing first order perturbation theory, a relevant dispersion relation has been derived for the time dependent states. Utilizing the η−e diagram along with the dispersion relation, it is revealed that the steady state solutions which lie on the branch I (C normal branch) of “ e0−δ” curve are stable and the solutions which belong to the branch II (C overlap branch) are unstable with respect to small aperiodic perturbations. The width of the unstable branch gradually decreases as the magnitude of external magnetic field is increased.

A study on the steady-state solutions of a Bursian diode in the presence of transverse magnetic field, when the electrons of the injected beam are turned back partially or totally

The properties of a steady-state planar vacuum diode driven by a cold electron beam have been investigated in the presence of an external transverse magnetic field, employing both the Eulerian and the Lagrangian formalism. With the help of a numerical scheme, the features of the steady-state solutions have been explored in the Eulerian frame, particularly for the case that corresponds to the potential distributions with a virtual cathode. However, exact analytical formulae for the potential and velocity profiles within the inter-electrode region have been derived with the Lagrangian description. In contrast to the previous work [Phys. Plasmas 22, 042110 (2015)], here we have emphasized the situation when electrons are reflected back to the emitter by the magnetic field. Both partial and complete reflection of the electrons due to the magnetic field have been taken into account. Using the emitter electric field as a characteristic parameter, steady-state solutions have been evaluated for specific values of...

Non-neutral plasma diode in the presence of a transverse magnetic field

An analytical study of the plasma states in non-neutral plasma diodes in the presence of an external transverse magnetic field is presented for an arbitrary neutralization parameter γ. Considerations are restricted to the regime where no electrons are turned around by the magnetic field. The emitter electric field strength E0 is used as a characteristic function to investigate the existence of solutions depending on the diode length, the applied voltage, the neutralization parameter, and the magnetic field strength. The potential distribution has a wave form for small magnitudes of the external magnetic field, as well as for the case when magnetic field is absent. A new family of solutions appears along with the Bursian ones. On the other hand, as the Larmor radius becomes comparable with the beam Debye length, oscillations in the potential disappear, and only the Bursian branches remain. Unlike the vacuum diode, there are steady state solutions for the negative values of the emitter field strength. As th...

Nonlinear oscillations in the Knudsen plasma diodes

Under analytical and numerical study are the kinetic phenomena inherent for nonlinear oscillations in 1D diodes in which charged particles are supplied from an emitter and move with no collision in the interelectrode spacing. An original numerical method (E,K code) is used to build up the ion and electron velocity distribution functions as well to study the structures forming in the course of the nonlinear oscillations both in the vacuum diode with monoenergetic electron beam and in the Knudsen diode with surface ionization. The oscillations are shown to occur owing to the Bursian-Pierce instability.

Stability properties of the steady state solutions of a non-neutral plasma diode when there is a uniform magnetic field along transverse direction

The stability properties of a non-neutral plasma diode [Pramanik et al., Phys. Plasmas 23, 103105 (2016)] have been investigated for the stationary states taking arbitrary value of the neutralization parameter. A constant magnetic field is also assumed to be applied externally along the transverse direction. The (η, e)-diagram technique is used to study the stability features of all types of solutions with respect to small aperiodic perturbations. Employing the first order perturbation theory, a relevant dispersion relation has been derived and analyzed for the regimes when electrons are not turned around by the magnetic field. These regimes of solutions belong to the “Normal C branch” and “C-overlap branch” of the “emitter field strength vs. diode gap”-diagrams. With the help of this dispersion relation, both aperiodic and oscillatory stability properties of such solutions have been presented.

Time-independent states of a non-neutral plasma diode when emitted electrons are partially turned around by a transverse magnetic field

An analytical study is presented on the steady states of a plasma diode that is uniformly occupied by infinitely massive ions of constant density and driven by a cold electron beam in the presence of an external transverse magnetic field. In contrast to our previous work [Pramanik et al., Phys. Plasmas 23, 062118 (2016)], here, we investigate the case when electrons are reflected back to the emitter by the magnetic field for arbitrary values of the neutralization parameter. Using the emitter electric field as a characteristic parameter, the steady-state solutions have been evaluated for the specific values of the diode gap, applied voltage, neutralization parameter, and magnetic field strength. It was found that unlike vacuum diodes (e.g., the Bursian diode), steady state solutions also exist for negative values of the emitter field strength. In case of the Bursian diode, only a single type of solutions (Bursian branches) was observed. However, for the Pierce diode, the new family of solutions appeared al...