PDF Publication Title:
Text from PDF Page: 254
Chapter 6 Hollow Cathodes Ion and Hall thrusters that utilize an electron discharge to ionize the propellant gas and create the plasma in the thruster require a cathode to emit the electrons. In addition, thrusters must neutralize the ion beam leaving the thruster by providing electrons emitted from a cathode into the beam. The properties of the cathode material, the physical configuration hollow cathode, and structure of the cathode plasma determine, to a large extent, the performance and life of both ion and Hall thrusters. 6.1 Introduction Early electron-bombardment ion thrusters developed in the 1960s utilized directly heated tungsten filaments as the cathode that produced electrons for the plasma discharge. Smaller tungsten filaments were also inserted into the ion beam to provide neutralizing electrons. Due to the high work function of tungsten, these filaments had to be operated at temperatures of over 2600 K in order to emit electron current densities in excess of 1 A/cm2. Operation at these temperatures requires high heater power, often on the order of the discharge power, which significantly reduces the efficiency of the thruster. In addition, the life of filament cathodes is limited by rapid evaporation of the filament material at the elevated temperatures and by sputtering of the tungsten surface exposed to the discharge plasma or the beam by ion bombardment. Filament cathode life was typically limited to the order of only hundreds of hours or less. While the use of filament cathodes permitted development of ion thruster accelerator grids and discharge chambers, they were inadequate for long-life space applications. These problems were solved by the development of hollow cathodes. A generic hollow cathode is shown in Fig. 6-1, where the cathode consists of a hollow refractory tube with an orifice plate on the downstream end. The tube has an insert in the shape of a cylinder that is placed inside the tube and pushed against 243PDF Image | Fundamentals of Electric Propulsion: Ion and Hall Thrusters
PDF Search Title:
Fundamentals of Electric Propulsion: Ion and Hall ThrustersOriginal File Name Searched:
Goebel__cmprsd_opt.pdfDIY PDF Search: Google It | Yahoo | Bing
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
IT XR Project Redstone NFT Available for Sale: NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Be part of the future with this NFT. Can be bought and sold but only one design NFT exists. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Turbine IT XR Project Redstone Design: NFT for sale... NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Includes all rights to this turbine design, including license for Fluid Handling Block I and II for the turbine assembly and housing. The NFT includes the blueprints (cad/cam), revenue streams, and all future development of the IT XR Project Redstone... More Info
Infinity Turbine ROT Radial Outflow Turbine 24 Design and Worldwide Rights: NFT for sale... NFT for the ROT 24 energy turbine. Be part of the future with this NFT. This design can be bought and sold but only one design NFT exists. You may manufacture the unit, or get the revenues from its sale from Infinity Turbine. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Supercritical CO2 10 Liter Extractor Design and Worldwide Rights: The Infinity Supercritical 10L CO2 extractor is for botanical oil extraction, which is rich in terpenes and can produce shelf ready full spectrum oil. With over 5 years of development, this industry leader mature extractor machine has been sold since 2015 and is part of many profitable businesses. The process can also be used for electrowinning, e-waste recycling, and lithium battery recycling, gold mining electronic wastes, precious metals. CO2 can also be used in a reverse fuel cell with nafion to make a gas-to-liquids fuel, such as methanol, ethanol and butanol or ethylene. Supercritical CO2 has also been used for treating nafion to make it more effective catalyst. This NFT is for the purchase of worldwide rights which includes the design. More Info
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
Infinity Turbine Products: Special for this month, any plans are $10,000 for complete Cad/Cam blueprints. License is for one build. Try before you buy a production license. May pay by Bitcoin or other Crypto. Products Page... More Info
| CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com | RSS | AMP |