Ion Propulsion

ION PROPULSION( SOLAR ELECTRIC PROPULSION)Presented By:

*Aviation and the Environment- Navigating the FutureMarch 30, 2006

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What is PROPULSION?Types of Rocket Propulsion.ION Propulsion. Ion Thruster Operation.

Power System .

Why solar Electric Propulsion?

Difference Between a ION Engine & CONVENTIONAL Engine.

Applications. Advantages.Draw Backs.Some Concluding Observations CONTENTS AT A GLANCE


* what is propulsion? PROPULSIONPropulsion moves things like spacecraft or jet planes forward by pushing something out of the back. Think of a balloon that you blow up and then release. The air rushing out of the back pushes the balloon forward. This happens because of a phenomenon described by Sir Isaac Newton: "every action has an equal and opposite reaction."


* TYPES OF ROCKET PROPULSION

Type Uses Advantages Disadvantages Solid fuel chemical propulsion main boostersimple, reliable, few moving parts, lots of thrust not restartableLiquid fuel chemical propulsion main booster, small control restartable, controllable, lots of thrust complex Cold-gas chemical propulsion small control restartable, controllable low thrust Ion in space boosterrestart able, controllable, high specific impulsecomplex


* ION PROPULSION An ion is simply an atom or molecule that is electrically charged.Plasma is an electrically neutral gas in which all positive and negative chargesfrom neutral atoms, negatively charged electrons, and positively charged ionsadd up to zero .Plasma is the building block for all types of electric propulsion, where electric and/or magnetic fields are used to push on the electrically charged ions and electrons to provide thrust. Examples of plasmas seen every day are lightning and fluorescent light bulbs.The conventional method for ionizing the propellant atoms in an ion thruster is called electron bombardment .


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When a high-energy electron (negative charge) collides with a propellant atom (neutral charge), a second electron is released, yielding two negative electrons and one positive ion .

The ionization process in a xenon ion thruster is shown here: e- + Xe0 => Xe+ + 2e-

An Ion rocket first strips negative electrons from the xenon atoms, leaving them as "ions", atoms with a net (positive) electric charge.

The ions can now be accelerated by electrical forces, to velocities much higher than those obtained from a hot gas, but without the need for a high temperature.


*Incidentally, the emerging jet of ions must be combined with a stream of negative electrons from a separate electron gun .Without this addition, only positive ions would be emitted, and the satellite would quickly become negatively charged by the stripped electrons left behind. The negative charge would then pull back the ions and undo all the work of the ion gun. Of all the exotic means of propulsion in space, this one is probably closest to practical use. Xenon atoms are injected into the propulsion chamber. They are heated and bombarded with electrons until they form a plasma, with electrons separated from the cores of the atoms, which become xenon ions


*The positively charged xenon ions move towards the back of the chamber. The expelled ions propel the ship forward. Electrons are shot from a cathode towards the ions behind the ship. The ions are neutralized, and the xenon atoms float away.


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*POWER SYSTEM USEDDS1 has solar panels that collect the Sun's light energy and convert it into electricity. The more light they receive, the more electricity they can make. If the panels get turned away from the Sun, even by a small amount, the efficiency of the solar collectors greatly decreases. All efforts are made to keep the solar panels pointed directly at the Sun. When it isn't possible to point the panels straight at the Sun ,DS1 switches to batteries for its power. As a spacecraft gets farther from the Sun, it's solar panels can make less electricity. Usually by the time a spacecraft gets to Mars, there isn't enough light to make electricity. DS1's power will drop off after DS1 gets past Mars .


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* why solar electric propulsion? Any vehicle must carry fuel in order to move. Ion engines are a way of moving a space ship through space without needing to carry and use the huge amounts of fuel that conventional rockets need .This has several advantages. One is that the less fuel a ship carries, the lighter it is and the easier it is to get it into space. Another advantage is that a ship that needs less fuel will not run out of fuel and stop working as quickly. Much of the energy in an ion rocket is provided by electricity, which can be made through solar panels "on the fly" instead of carried into space.


* Difference between a conventional and ion engineBoth kinds of rockets move the ship forward by making thrust. This thrust is made by propelling matter out of the back of the ship. Ion engines are different from chemical engines (engines that work by burning liquid or solid fuel) in where they get their energy and how they produce thrust .Chemical engines work by combining fuel with an oxidizer. That makes a gas that expands and rushes out the back of the engine, making thrust. Chemical engines are mass-limited engines. What this means is that how much power a chemical engine has depends on is how much fuel and oxidizer the rocket can carry. When the propellant runs out then the rocket cannot go any faster. Ion engines take very small amounts of gas and accelerate it to very high speeds. Ion engines are limited by energy, not by mass. Therefore "running out of gas" is not a large problem with ion engines.


* APPLICATIONSIon thrusters have many applications for in-space propulsion. The best applications of the thrusters make use of the long lifetime when significant thrust is not needed. Examples of this include orbit transfers, attitude adjustments, drag compensation for low earth orbits, and ultra fine adjustments for more scientific missions. Ion thrusters can also be used for interplanetary and deep space missions where time is not crucial. Continuous thrust over a very long time can potentially build up a larger velocity than traditional chemical rockets.


* SERTThe first was SERT (Space Electric Rocket Test) which tested two mercury ion engines for thousands of running hours in the 1970's.Deep Space 1NASA has developed an ion thruster called NSTAR for use in their interplanetary missions. This thruster was tested in the highly successful space probe Deep Space 1, launched in 1998. Hughes has developed the XIPS (Xenon Ion Propulsion System) for performing stationkeeping on geosynchronous satellites.DS1 ION ENGINE


* ArtemisOn 12 July 2001, the European Space Agency failed to launch their Artemis telecommunication satellite, and left it in a decaying orbit. The satellite's chemical propellant supply was sufficient to transfer it to a semi-stable orbit, and over the next 18 months the experimental onboard ion propulsion system (intended for secondary station keeping and maneuvering) was utilized to transfer it to a geostationary orbit.


* HayabusaThe Japanese space agency's Hayabusa, which was launched in 2003 and successfully rendezvoused with the asteroid 25143 Itokawa and remained in close proximity for many months to collect samples and information, is powered by four xenon Ion Engines. It is using xenon ions generated by microwave ECR, and a Carbon / Carbon-composite material for acceleration grid which is resistant to erosion.


* DawnDawn was launched on 27 September 2007 to explore the dwarf planet Ceres and the asteroid Vesta. To cruise from Earth to its targets it will use three Deep Space 1 heritage Xenon ion thrusters (firing only one at a time) to take it in a long outward spiral. An extended mission in which Dawn explores other asteroids after Ceres is also possible. Dawn's ion drive is capable of accelerating from 0 to 60mph (97km/h) in 4 days.


* FUTURE APPLICATIONS LISA PathfinderLISA Pathfinder is an ESA spacecraft to be launched in 2009. It will not use ion thrusters as its primary propulsion system, but will use both colloid thrusters and FEEP for very precise attitude controlthe low thrusts of these propulsion devices make it possible to move the spacecraft incremental distances very accurately. It is a test for the possible LISA mission.LISA pathfinder structure


* ADVANTAGESThe ion propulsion systems efficient use of fuel and electrical power enable modern spacecraft to travel farther, faster, and cheaper than any other propulsion technology currently available. Ion engines take very small amounts of gas and accelerate it to very high speeds, unlike chemical engines which take large amounts of gas and spew it out at a slow speed. This means that an ion engine uses a lot less fuel. Ion engines are limited by energy, not by mass. Therefore "running out of gas" is not a large problem with ion engines. Ion propulsion is a great technology to move ships once they are in space, and it is especially good for very long journeys.


*DRAWBACKSIon engines are limited by energy .Ion engines are limited by how much energy (electricity) that a rocket can carry or how much energy the solar panels can collect.Could not be used on earth ,it work only in space.Due to the high specific impulse of ion propulsion, it gives low amounts of thrust.


*[email protected] SOME CONCLUDING OBSERVATIONSIon propulsion plays a significant role in the future Aerospace transportation . Solar thermal propulsion systems would be less expensive, much simpler and more efficient than todays rocket engines. Rocket engines that tap the Suns energy could dramatically reduce the cost of putting payloads, such as communications satellites, in orbit .The compact systems require much smaller propellant tanks than conventional chemical rockets, so theres room for larger payloads. Applications of the technology include placing satellites into their final Earth orbit positions and adjusting satellites on orbit


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*Background on my roleStory of JB/Will and ThunderstormFinding the balance

*What Ill Cover

* Over 1.6 billion passengers worldwide use the world's airlines for business and leisure travel. Research indicates that by 2010, this number could exceed 2.3 billion. Air transport is essential for world business creating jobs and opening up new market opportunities by attracting businesses to locations in the developed and developing world. Air transport provides 28 million direct, indirect and induced jobs worldwide and transports over 40% of world trade of goods (by value. It plays a vital role in development. In Africa for example, the role of air transport is especially important given the absence of effective ground transport networks. Air transport generates 470,000 jobs in Africa and contributes US$ 11.3 billion to African GDP. Changi Airport in Singapore generates over 9% of GDP. *Aircraft Noise is not a new issue- in fact it was there from nearly the beginning.Most folks know that in 2003 we celebrated the 100th anniversiary of flight. Most people dont know that 2003 was also the 93rd anniversary of the first editoal aainst aircraft noise.

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The good news- and its important to remember is that today we carry more passengers each year around the world on airraft than the poplation of the world in 2003 (1.6 billion). So clearly weve had some success.

Lets put that in some perspective in the US

****First, the FAA launahced an effort several years ago to develop new and improved models and toolsThe heart of what were trying to do is move away from the stove pipes on noise and emissions- and be able to provide an integrated approach for analysis and policy making.As this chart tries to convey- in decisions about design and operations-there are numbers of trades-offs between noise and emissions.Improved aerodynamic efficiency and reduced weight- Reduces CO2 by improving fuel efficiency and required thrust- Reduces Noise by reducing required thrustReduces NOx by reducing combustion temperatureIncreased Engine Pressure Ratio- Reduced Fuel Burn / CO2 by improving thermal efficiency- Reduces lower power emissions (HC and CO)Increases NOx by increasing combustion temperatureIncreased engine bypass ratio (high bypass turbofan)- Reduced Fuel Burn / CO2 by improving propulsive efficiency- Reduces Noise by reducing fan pressure ratio and exhaust velocity

**The contentiousness of the debate

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*In cooperation with the National Academy of Sciences- we lanuched and effort to develop the tools wed need. Environmental Design Space (EDS) Provide integrated transparent analysis of noise and emissions at the aircraft level Aviation Environmental Design Tool (AEDT) - Provide common, transparent integrated capability of generating interrelationships between noise and emissions and amongst emissions at the local and global levels with the objective of providing technical information to support aviation environmental policyAviation Environmental Portfolio Management Tool (APMT) Combines economics with AEDT output to provide the common, transparent cost/benefit methodology needed to optimize national aviation policy in harmony with environmental policy

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Ion Propulsion