Presentation on theme: "Nanoparticle Electric Propulsion for Space Exploration Phys 483 Monday, March 31 2008 Team 1: Perry Young, Kiyoshi Masui, Mark Hoidas, Andrew Harris."— Presentation transcript:
Nanoparticle Electric Propulsion for Space Exploration Phys 483 Monday, March 31 2008 Team 1: Perry Young, Kiyoshi Masui, Mark Hoidas, Andrew Harris
Deep Space 1 Launched in October 1998 Meant to test 12 new technologies that were too risky for previous missions Among those technologies was an ion thruster, a type of electric propulsion Represented a departure from conventional chemical propellants Deep Space 1 completed successfully completed an extended mission and was retired at the start of 2002
The ion thrusters provide a high fuel efficiency, reducing the propellant load, and a low thrust, which is compensated for through long acceleration times. Recently it has been proposed that this system could be improved upon by using conductive nanoparticles in place of the xenon ions, which would increase the level of control that can be gained over the induced charge. This is termed a nanoparticle field extraction thruster or nanoFET
Background Propellant is a major component of mass transported in space travel Solar electrical energy is available in the solar system Mass efficiency can be increased by electrically accelerating propellant to high energy More momentum gained per unit mass of propellant
Theory and Definitions Propulsion systems often quote specific impulse I sp (in s/g), momentum gained per unit mass of propellant I sp describes how effectively an engine consumes mass Another measure of an engine is thrust to power ratio which describes how effectively an engine consumes energy There is a trade off between these two quantities, classically:
Ion Engines Comparable in concept to nanoparticle electric propulsion Ion engines have already been tested in space flight Provide low trust but excellent propellant efficiency
Apparatus Cylindrical nanoparticles transported through a thin layer of liquid, which is either dielectric or conductive Particles charged and field-focusing extracts them from liquid Charges particles accelerated through the a potential and expelled from thruster
Dielectric Liquid Configuration Particles charged by contact with a conducting plate Particles with sufficient charge travel from the plate to liquid surface through the potential V 0 Main loss due to viscous drag and charge loss traveling from the plate to the liquid-vacuum interface
Conductive Liquid Configuration Particles only become charged at liquid surface due to vacuum potential Passive transport to surface through thermal motion or convective mixing No charge losses due to liquid
Apparatus Stacked gate design Ability to provide large acceleration potentials without exceed individual gate breakdown threshold Decoupling of acceleration potential from potential applied to liquid in dielectric configuration
The specific charge on a nanoparticle in a dielectric liquid is a function of the applied field, the fluid properties and especially the particle geometry This geometry can be controlled The relationship between specific charge and specific impulse therefore implies that the Isp can be controlled by the particle geometry By using several sets of nanoparticles a very wide range of Isp conditions can be obtained.
Efficiency Carbon Nanotube particles 1:5 nm diameter|100 nm length 2:1 nm diameter| 10 nm length 3:1 nm diameter | 3.5 nm length Potential: 800 V – 10 kV Simulation with three different sizes of carbon nanotubes in silicone oil Combined, they span the Isp range of all other electrical propulsion technologies.
Summary -reduce propellant load -flexibility (allowing Isp optimization) -engine design and mission planning are decoupled -compact low mass due to MEMS technology -lower maintenance then ion engines (Xenon surface erosion) -avoid complications due to ion optics Nanoness -control of the specific charge with respect to the particle geometry is specific to nanoparticles -replacing microscopic atoms with nanoparticles which can be electrostatically charged