ion propulsion thruster engine

about electrical thruster working, classification, application, advantage, propellent used, disadvantage, conclusion and current mission

1. A Seminar re p ort On ION PROPULSION THRUSTER Submitted for partial fulfillment for award of degree of BACHELOR OF TECHNOLOGY IN Electrical Engineering By piyush Mentor Dr.R.P.PAYASI Seminar Coordinator Prof. Varun Kumar Department of Electrical Engineering KAMLA NEHRU INSTITUTE OF TECHNOLOGY, SULTANPUR (U.P.) (An Autonomous Gov. Engineering Institute) Affiliated to Dr. A P J ABDUL KALAM TECHNICAL UNIVERSITY LUCKNOW, INDIA 1

2. CONTENTS 1) INTRODUCTION 2) PARTS OF IPS 3) CLASSIFICATION 4) WORKING PROCESS 5) APPLICATION 6) PROPELLENT USED 7) ADVANTAGE 8) DISADVANTAGE 9) CURRENT MISSION 10) REFERENCES

3. INTRODUCTION 1) Chemical Propulsion involves the chemical reaction of propellants to move or control a spacecraft 2) Non-chemical Propulsion eliminates the use of chemical reactants 3) The acceleration of gases for the purpose of producing propulsive thrust by electric heating, electric body forces, and/oR electric and magnetic body forces . 4) A propulsion system is a machine that produces thrust to push an object forward. On airplanes, thrust is usually generated through some application of Newton's third law of action and reaction. A gas, or working fluid, is accelerated by the engine, and the reaction to this acceleration produces a force on the engine. HISTORY 1903 -- K. E. Tsiolkovsky derived the “ Tsiolkovsky ” or “Rocket” Equation commonly used to show the benefits of electric propulsion 1906 -- R. Goddard wrote about the possibility of electric rockets 1911 -- K. E. Tsiolkovsky independently wrote about electric rockets 1929 -- World’s first electric thruster demonstrated by V. P. Glushko at the Gas Dynamics Laboratory in Lenningrad 1960 -- First “broad-beam” ion thruster operated in the U.S. at the NASA Lewis (now Glenn) Research Center 1964 -- First successful sub-orbital demonstration of an ion engine (SERT I) by the U.S. 1964 -- First use of an electric thruster on an interplanetary probe ( Zond 2) by the USSR 1970 -- Long duration test of mercury ion thrusters in space (SERT II) by the U.S. 1972 -- First operation of a xenon stationary plasma thruster (SPT-50) in space (Meteor) by the USSR 1993 -- First use of hydrazine arcjets on a commercial communications 3 Electric propulsion is a

4. ELECTRIC PROPULSION 1.Power source : power source can be any source of electrical power, but solar and nuclear are the primary options. A solar electric propulsion system (SEP) uses sunlight and solar cells for power generation.  A nuclear electric propulsion system (NEP) uses a nuclear heat source coupled to an electric generator. 2.Power processing unit (PPU): The PPU converts the electrical power generated by the power source into the power required for each component of the ion thruster . It generates the voltages required by the ion optics and discharge chamber and the high currents required for the hollow cathodes. 3.Propellent management system: The PMS controls the propellant flow from the propellant tank to the thruster and hollow cathodes. Modern PMS units have evolved to a level of sophisticated design that no longer requires moving parts. 4.The computer control : The control computer controls and monitors system performance 5.Ion Thruster: Then processes the propellant and power to perform work. 4 PARTS OF IPS(Ion Propulsion system) Ion propulsion system consists of the following five parts : Power source Power processing unit Propellant management system The control computer Ion thruster

5. CLASSIFICATION They are broadly classified as: 1)Electrostatic Propulsion   2)Electromagnetic Propulsion 5 Ion propulsion process: The fuel used by modern ion engines is xenon gas which is four times heavier than air When the ion engine is running, electrons are emitted from a hollow cathode tube called as discharge cathode. These electrons enter a magnet-ringed chamber, where they strike the xenon atoms. These electrons hits the electrons of xenon atom as it consists of 54 electrons . This results in the formation of ions in discharge chamber High-strength magnets are placed along the discharge chamber walls so that as electrons approach the walls, they are redirected into the discharge chamber by the magnetic field At the rear of the chamber, a pair of metal grids is charged positively and negatively, respectively, with up to 1,280 volts of electricity The force of this electric charge exerts a strong electrostatic pull on the xenon ions The xenon ions shoot out the back of the engine at high speeds which propels the spacecraft in opposite direction and produces thrust force . The force of this electric charge exerts a strong electrostatic pull on the xenon ions The xenon ions shoot out the back of the engine at high speeds which propels the spacecraft in opposite direction and produces thrust force .

6. 6 1)Electrostatic ion thruster: This type of thruster commonly use xenon gas which has no charge and it is ionized by bombarding with energetic electrons. These electrons are provided from hot cathode filament and accelerated into electric field of cathode fall to anode. The positive ions are extracted after bombarding of electrons with xenon atoms, and these ions are accelerated by electrostatic forces The electric fields used for acceleration are generated by electrodes positioned at the end of the thruster ,such set of electrodes are called as ion optics or grids. Since the ions are generated in a region of high positive and the accelerator grid's potential is negative, the ions are attracted toward the accelerator grid and are focused out of the discharge chamber through the apertures, creating thousands of ion jets. The electric fields used for acceleration are generated by electrodes positioned at the end of the thruster ,such set of electrodes are called as ion optics or grids. Some ion thrusters use a two-electrode system, where the upstream electrode(screen grid) is charged highly positive, and the downstream electrode(accelerator grid) is charged highly negative. Since the ions are generated in a region of high positive and the accelerator grid's potential is negative, the ions are attracted toward the accelerator grid and are focused out of the discharge chamber through the apertures, creating thousands of ion jets. Because the ion thruster expels a large amount of positive ions, an equal amount of negative charge must be expelled to keep the total charge of the exhaust beam neutral. A second hollow cathode called the neutralizer is located on the downstream of the thruster and expels the needed electrons. thus how an electrostatic thruster produces thrust with the help of ions and propells the spacecraft Amount of thrust       At full throttle, the ion engine will consume 2,500 watts of electrical power, and put out 1/50th of a pound of thrust Ion thrusters are capable of propelling a spacecraft up to 90,000 meters per second (over 200,000mph)   thrusters can deliver up to 0.5 Newtons (0.1 pounds) of thrust

7. 7 Test data of some ion thrusters Engine Propellant Input power (kW) Specific impulse  (s) Thrust (mN) Thruster mass (kg) NSTAR Xenon 2.3 3300–1700 [29] 92 max. [13] PPS-1350  Hall effect Xenon 1.5 1660 90 5.3 NEXT [13] Xenon 6.9 [30] 4190 [30][31][32] 236 max. [13][32] NEXIS [33] Xenon 20.5 RIT 22 [34] Xenon 5 BHT8000 [35] Xenon 8 2210 449 25 Hall effect Xenon 75 [ citation needed ] FEEP Liquid caesium 6×10 −5  – 0.06 6000–10000 [19] 0.001–1 [19] NASA’s Evolutionary Xenon Thruster (NEXT) at NASA’s JPL

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9. 9 NASA’s Deep Space One Ion Engine

10. 10   APPLICATIONS Ion thrusters have many applications for in-space propulsion   The best applications of the ion thrusters make use of the long lifetime when significant thrust is not needed.   This type of propulsive device can also be used for interplanetary and deep space missions where time is not crucial   Used to spiral at lower altitudes on vesta   Helps Spacecraft Cruise Solar System on the Cheap   PROPELLENT   Many current designs use xenon gas due to its low ionization energy, reasonably high atomic number, inert nature, and low erosion   Ion thrusters use inert gas for propellant, eliminating the risk of explosions   The usual propellant is xenon, but other gases such as krypton and argon may be used.   ADVANTAGES   on propulsion could be used for a manned mission to Mars   Ion propulsion makes efficient use of the onboard fuel by accelerating it to a velocity ten times that of chemical rockets   The ion propulsion system, although highly efficient, is very gentle in its thrust Less expensive launch vehicle is required when compared to chemical propulsion . Less amount of propellant carrying tanks which reduces weight of spacecraft   With xenon, it is possible to reduce propellant mass onboard a spacecraft by up to 90 percent The advantages of having less onboard propellant include a lighter spacecraft, and, since launch costs are set based on spacecraft weight, reduced launch cost..   Additional velocity can be obtained   Greater life time when compared to other propulsive devices   Continuous thrust over a very long time can build up a larger velocity than traditional chemical rockets   High specific impulse , high efficiency

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12. ELECTROMAGNETIC:PPT PPTs use solid Teflon propellant to deliver specific impulses in the 900 - 1,200 s range and very low, precise impulse "bits" (10-1,000 μNs ) at low average power (< 1 to 100 W) PPTs inherently inefficient (η ~5%) Simplicity and low impulse bits provide highly useful Precision-flying of a spacecraft constellation PPT consists of a coiled spring that feeds Teflon propellant bar, an igniter plug to initiate a small-trigger electrical discharge, a capacitor, and electrodes through which current flows Plasma is created by ablating Teflon from discharge of capacitor across electrodes Plasma is then accelerated to generate thrust by Lorenz force that is established by current and its induced magnetic field

13. 14 DISADVANTAGES Unlike a chemical propulsion system ion propulsion produces gentle amount of thrust but for a long duration Ion propulsion system is mostly applicable only for deep space missions Cost of propellant used is very expensive Complex power coditioning ,high voltages Single propellant Low thrust per unit area Electric Propulsion Applications ISS INTERPLANETARY MISSION COMMERCIAL/DEFENSE

14. Conclusion 1 ) Electric thrusters in general are about 1.5 times as efficient as a good chemical propulsion system 2) A parameter called an specific impulse comes into play here. (~20,000 s) 3) So why use an electric thruster ? If the mission is not time sensitive an electric propulsion system will use less fuel, and therefore cost less to launch into space. On average it currently costs about $10,000 for every kilogram launched into low Earth orbit. Therefore if time is not a crucial issue the delay can be worth the money saved at launch . . 4) the propellant chose should not cause erosion of the thruster to any great degree to permit long life; and should not contaminate the vehicle 5) In 1998, Deep Space 1 became the first spacecraft to use ion propulsion to reach destinations in the solar system CURRENT MISSION

15. REFERENCES 1 . Rocket and space craft propulsion book by Martin J . L . Turner Third Edition. 2. Rocket propulsion element by George p. Sutton Seventh Edition. 3. Electric Propulsion: Which One For My Spacecraft? Ian J. E. Jordan JHU, Whiting School of Engineering. 4. A Critical History of Electric Propulsion: The First Fifty Years (1906-1956) Edgar Y . Choueiri 5. Fundamentals of Electric Propulsion: Ion and Hall Thrusters Dan M. Goebel and Ira Katz 6. M.S. El-Genk. Energy conversion options for advanced radioisotope power systems. In Space Technology and Applications International Forum (STAIF 2003), volume 654(1), pages 368–375. American Institute of Physics, New York, 2003. 7. S. Oleson and I. Katz. Electric propulsion for Project Prometheus. In 39th Joint Propulsion Conference, Huntsville, AL, 2003. AIAA-2003- 5279 8. N.A. Rynin . Tsiolkovsky : His Life, Writings and Rockets. Academy of Sciences of the USSR, Leningrad, 1931. 9. R. G. Jahn . Physics of Electric Propulsion. McGraw-Hill, New York, 1968. 10. R.H. Goddard. The green notebooks, vol. # 1. The Dr. Robert H. Goddard Collection at Clark University Archives, Clark University, Worceseter , MA 01610. 11. Stuhlinger , E., Electric Propulsion Development, Progress in Astronautics and Aeronautics , v. 9, AIAA, Academic Press, 1963. Electric Propulsion Websites: 1.Frisbee, R. http://sec353.jpl.nasa.gov/apc/index.html . 2.Advanced Space Propulsion Research Workshop May 31 / June 2, 2000 - JPL. Proceedings papers may be found at http://apc2000.jpl.nasa.gov/ . 3.A somewhat out of date compilation of electric propulsion sites may be found at http://www.irs.unistuttgart.de/SURF/ep_sites.html