Laser Accelerated Plasma For Space Propulsion
Laser Accelerated Plasma For Space Propulsion

Terry Kammash
Nuclear Engineering and Radiological Sciences
The University of Michigan
Ann Arbor, MI 48109

Recently conducted experiments at the University of Michigan and elsewhere have shown that ultra short pulse [ultra fast] lasers could accelerate charged particles to relativistic speeds. For example a picosecond laser pulse with only one joule of energy can accelerate an electron to MeV energy in just a few microns distance. This takes place through the high gradient potential that manifests itself in an electric field of a gigavolt per cm which in turn accelerates the electron to a megavolt energy over a distance of 10 microns. Current achievable laser peak power of about 10e15 Watts has been utilized in the study of relativistic non-linear optics in plasmas, and it is expected that laser power values will be reached in the near future that will accelerate protons to energies equal to their rest mass energy. That readily means that when such particles are ejected from a system at 0.866 the speed of light they will produce a specific impulse of 26 million seconds. Current experiments have also demonstrated that a beam of MeV protons containing more than 10e10 particles has been accelerated by an electric field of 10 GeV/cm corresponding to a laser power of about 100 TW. On the basis of these accomplishments it is reasonable to project with little risk that with modest modifications of present day systems including rep rates of 10-1000, accelerating 10e18 protons to 100 MeV energy will be quite achievable. If utilized as a propulsion device such a system will produce about 0.22 Kilonewtons of thrust at a specific impulse of about 13 million seconds. This will require a 15 KJ laser at a femtosecond pulse length which when incorporated in a propulsion system such a vehicle will have a dry mass of about 3.6 mT based on previous laser-fusion propulsion system design. When utilized in a constant thrust,acceleration/deceleration type of mission trajectory it is shown that a round trip to Mars will take about 53 days, and a fly-by mission to the Oort cloud at 10,000 AU about 7.5 years.

Terry Kammash
Nuclear Engineering and Radiological Sciences
The University of Michigan
Ann Arbor, MI 48109

Recently conducted experiments at the University of Michigan and elsewhere have shown that ultra short pulse [ultra fast] lasers could accelerate charged particles to relativistic speeds. For example a picosecond laser pulse with only one joule of energy can accelerate an electron to MeV energy in just a few microns distance. This takes place through the high gradient potential that manifests itself in an electric field of a gigavolt per cm which in turn accelerates the electron to a megavolt energy over a distance of 10 microns. Current achievable laser peak power of about 10e15 Watts has been utilized in the study of relativistic non-linear optics in plasmas, and it is expected that laser power values will be reached in the near future that will accelerate protons to energies equal to their rest mass energy. That readily means that when such particles are ejected from a system at 0.866 the speed of light they will produce a specific impulse of 26 million seconds. Current experiments have also demonstrated that a beam of MeV protons containing more than 10e10 particles has been accelerated by an electric field of 10 GeV/cm corresponding to a laser power of about 100 TW. On the basis of these accomplishments it is reasonable to project with little risk that with modest modifications of present day systems including rep rates of 10-1000, accelerating 10e18 protons to 100 MeV energy will be quite achievable. If utilized as a propulsion device such a system will produce about 0.22 Kilonewtons of thrust at a specific impulse of about 13 million seconds. This will require a 15 KJ laser at a femtosecond pulse length which when incorporated in a propulsion system such a vehicle will have a dry mass of about 3.6 mT based on previous laser-fusion propulsion system design. When utilized in a constant thrust,acceleration/deceleration type of mission trajectory it is shown that a round trip to Mars will take about 53 days, and a fly-by mission to the Oort cloud at 10,000 AU about 7.5 years.