Development of a Radioisotope Heated Hollow Cathode

2014 ◽  
Vol 598 ◽  
pp. 331-341 ◽  
Author(s):  
Kalomba Mboyi ◽  
Jun Xue Ren ◽  
Yu Liu
Keyword(s):  
Hollow Cathode ◽  
Power Saving ◽  
Thermionic Emission ◽  
Heat Sources ◽  
Ion Thruster ◽  
Hollow Cathodes ◽  
Self Sufficiency ◽  
Strontium 90 ◽  
New Type ◽  
Thermionic Emissions

A new type of hollow cathode using a radioisotope heat source instead of a conventional sheathed heater was introduced and it achieved thermionic emission performances similar to the ones of conventional hollow cathodes. Strontium-90, Plutonium-238 and Curium-244 were chosen as radioisotope heat sources and a thermal reductive layer was also used to obtain precise thermionic emissions. A new system design methodology called the Self-Sufficiency Principle was introduced and was applied by powering the keeper electrode with the radioisotope decay heat using a radioisotope thermoelectric generator (RTG). The heater supply of the hollow cathode power configuration was replaced with a RTG supply and the mode of operation of the device was modified because radioisotope heat sources cannot be switched off. This hollow cathode was then benchmarked against two ion thruster configurations and a maximal overall power saving of 3% was achieved. Its advantages are its power saving capability and scalability but it can however be voluminous, heavy and potentially hazardous. Further research in this field ought to explore the range of applications of this new power-free electron emission technology.

Hollow Cathode With Low Work Function Electride Insert

2011 ◽  
Author(s):  
Lauren P. Rand ◽  
Ryne M. Waggoner ◽  
John D. Williams
Keyword(s):  
Work Function ◽  
Hollow Cathode ◽  
Electric Propulsion ◽  
Thermionic Emission ◽  
Basic Material ◽  
Successful Operation ◽  
Hollow Cathodes ◽  
Start Up ◽  
Attractive Option ◽  
Lower Temperature

Hollow cathodes are critical devices in the successful operation of electric propulsion thrusters. Cathodes featuring C12A7:electride as an ultra-low work function thermionic emitter are hypothesized to have faster start-up times and lower operating temperatures than conventional hollow cathodes. C12A7:electride is a crystalline ceramic in which electrons clathrated in sub-nanometer sized cages act as a conductive medium. Due to its unique atomic structure and large size, C12A7:electride has a predicted work function of 0.6 eV. As a result, C12A7:electride is an attractive option for a thermionic emission material in a hollow cathode. Calculations predict equivalent levels of current emission as LaB6 or CeB6, but at much lower temperature. C12A7:electride is stable at temperatures below its re-crystallization temperature (∼1000 °C) and is not consumed during operation. C12A7:electride has been fabricated at CSU using a simplified, one-step approach that results in a more conductive material than previously reported. The material has been integrated into a novel hollow cathode design that takes advantage of its unique properties to decrease start-up time and power consumption. Our paper will discuss preliminary results obtained with several cathode configurations. In addition, results from the experimental determination of basic material properties such as conductivity and work function will be presented. Strategies to further enhance electron emission through surface modifications will also be discussed.

PLANETARY SELF-ORGANIZATION

2020 ◽  
Vol 42 (3) ◽  
pp. 271-282
Author(s):  
OLEG IVANOV
Keyword(s):  
Dynamical System ◽  
Heat Source ◽  
Mantle Convection ◽  
Plate Tectonics ◽  
Rotation Speed ◽  
Self Organization ◽  
Heat Sources ◽  
Kinematic Parameters ◽  
The Earth ◽  
New Type

The general characteristics of planetary systems are described. Well-known heat sources of evolution are considered. A new type of heat source, variations of kinematic parameters in a dynamical system, is proposed. The inconsistency of the perovskite-post-perovskite heat model is proved. Calculations of inertia moments relative to the D boundary on the Earth are given. The 9 times difference allows us to claim that the sliding of the upper layers at the Earth's rotation speed variations emit heat by viscous friction.This heat is the basis of mantle convection and lithospheric plate tectonics.

Resistive MHD modes in hollow cathodes external plasma

2021 ◽  
Author(s):  
Giulia Becatti ◽  
Francesco Burgalassi ◽  
Fabrizio Paganucci ◽  
Matteo Zuin ◽  
Dan M Goebel
Keyword(s):  
Magnetic Field ◽  
Hollow Cathode ◽  
Electric Propulsion ◽  
Axial Magnetic Field ◽  
Mhd Equations ◽  
Linear Perturbation ◽  
Plasma Parameters ◽  
Hollow Cathodes ◽  
Plume Region ◽  
Helical Mode

Abstract A significant number of plasma instabilities occur in the region just outside of hollow cathodes, depending on the injected gas flow, the current level and the application of an external magnetic field. In particular, the presence of an axial magnetic field induces a helical mode, affecting all the plasma parameters and the total current transported by the plasma. To explore the onset and behavior of this helical mode, the fluctuations in the plasma parameters in the current-carrying plume outside of a hollow cathode discharge have been investigated. The hollow cathode was operated at a current of 25 A, and at variable levels of propellant flow rate and applied magnetic fields. Electromagnetic probes were used to measure the electromagnetic fluctuations, and correlation analysis between each of the probe signals provided spatial-temporal characterization of the generated waves. Time-averaged plasma parameters, such as plasma potential and ion energy distribution function, were also collected in the near-cathode plume region by means of scanning emissive probe and retarding potential analyzer. The results show that the helical mode exists in the cathode plume at sufficiently high applied magnetic field, and is characterized by the presence of a finite electromagnetic component in the axial direction, detectable at discharge currents $\geq$ 25 A. A theoretical analysis of this mode reveals that one possible explanation is consistent with the hypotheses of resistive magnetohydrodynamics, which predicts the presence of helical modes in the forms of resistive kink. The analysis has been carried out by linear perturbation of the resistive MHD equations, from which it is possible to obtain the dispersion relation of the mode and find the $k-\omega$ unstable branch associated with the instability. These findings provided the basis for more detailed investigation of resistive MHD modes and their effect in the plume of hollow cathodes developed for electric propulsion application.

Thermal Analysis of Ion Thruster Hollow Cathodes

2010 ◽  
Vol 22 (5) ◽  
pp. 1149-1152 ◽  
Author(s):  
孙明明 Sun Mingming ◽  
顾佐 Gu Zuo ◽  
郭宁 Guo Ning ◽  
李娟 Li Juan
Keyword(s):  
Thermal Analysis ◽  
Ion Thruster ◽  
Hollow Cathodes

scholarly journals Methods for optimal loading of the prosumer’s heat source during the heating period

2019 ◽  
Vol 102 ◽  
pp. 02006
Author(s):  
Ivan Postnikov ◽  
Andrey Penkovskii
Keyword(s):  
District Heating ◽  
Time Interval ◽  
Test Scheme ◽  
Heat Sources ◽  
Heating Period ◽  
Heating Systems ◽  
Optimal Loading ◽  
Heat Loading ◽  
New Type ◽  
The One

The paper the one of current problem of transition of district heating systems (DHS) to the new type of intelligent and integrated systems. This problem is related to the implementation the technology of prosumer, which allows regulating its own heat loading ensuring the most efficiency heating modes by using its own heat sources (HS) and/or heat storages. The statement of considered problem is formulated as the search of the optimal loading relation between the own distributed HS of prosumer and the district HS of DHS, based on the criterion of minimal cost on heating to prosumer for each calculated time interval during the heating period. The practical researches based on calculating experiment using the test scheme of DHS is provided. The results of calculations are presented as diagram of prosumer’s and district HS loading for the considered DHS scheme, as well as the economic benefit when using distributed generation of prosumers.

Production of High Energy Ions Near an Ion Thruster Discharge Hollow Cathode

2006 ◽  
Author(s):  
Ira Katz ◽  
Ioannis Mikellides ◽  
Dan Goebel ◽  
Kristina Jameson ◽  
Richard Wirz ◽  
...  
Keyword(s):  
Hollow Cathode ◽  
High Energy ◽  
Ion Thruster ◽  
High Energy Ions

Operation of a lightweight power conditioner with a hollow-cathode ion thruster

1971 ◽  
Vol 8 (3) ◽  
pp. 245-250 ◽  
Author(s):  
E. V. PAWLIK ◽  
E. N. COSTOGUE ◽  
W. C. SCHAEFER
Keyword(s):  
Hollow Cathode ◽  
Ion Thruster ◽  
Power Conditioner

scholarly journals Foculi (fire pots) discovered at the legionary fortress of Potaissa. Case study: centuriae from praetentura sinistra

2018 ◽  
Vol 55 ◽  
pp. 117-139
Author(s):  
Luciana Nedelea ◽  
Keyword(s):  
Ceramic Material ◽  
Careful Analysis ◽  
Living Conditions ◽  
Heat Sources ◽  
Initial Number ◽  
Heating Systems ◽  
New Type ◽  
First Time ◽  
Ceramic Studies

Faced with a tumultuous end of the 2nd century and the harsh realities of the 3rd century AD, the Roman legionaries of Potaissa were forced to adapt to new living conditions and to overcome their daily needs by replacing and using the materials that were at hand or most convenient and easy to acquire at that time. One of the noteworthy observations here is the fact that almost no traces of heating systems have been identified. This situation raised different questions, as it is very hard to imagine how soldiers survived the harsh winters of Roman Dacia without heat sources. The answer came after a careful analysis of the ceramic material unearthed here. As a result, a new type of pottery has been identified, having bronze braziers as their precursor. It is for the first time that this type of pottery has been identified in Romania, as far as ceramic studies are concerned. In the praetentura sinistra, which will be the focus of this article, a total of 1621 wares were identified and analyzed, out of which 22% (218) are represented by this new type which we will call foculus/foculi. A number of approximately 1000 such earthen pots have been discovered in the entire Roman fortress, bearing in mind the fact that mostly rims and bases were kept during the archaeological campaigns throughout the years. We can estimate that their initial number was considerably higher.

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