VASIMR

VASIMR , acronym of Variable specific pulse magnetoplasma rocket (Rocket magnetoplasma with variable specific impulse), is a space type of propellent with plasma. It uses fields and electromagnetic radiations variable (without electrode S) to heat, to ionize and accelerate a Propergol vaporized (Hydrogène or Hélium).

VASIMR is a general-purpose, alternative solution with the two specialized systems existing which are the engines with high Poussée and weak specific Impulsion (like the rocket engines with chemical Propulsion) on a side, and engines with weak push and high specific impulse (like the ionic driving ) of the other, because it is able to function in the two modes by adjusting constantly its parameters of operation.

Principle

VASIMR with the characteristic to call upon the three aspects of the electric propulsion: heating by electromagnetic induction and relaxation of the Gas ( thermoelectric propulsion ); ionization and acceleration of the Ion S of plasma in a induced Electric field ( ionic propulsion ); internal containment of plasma, guidance and control of the external jet by magnetic field ( electromagnetic propulsion ).

# the neutral gas (hydrogen or helium) is injected in entry of the device.
# a tube in quartz collects and confines this neutral gas before its ionization.
# a " antenna hélicon" special pre-ionizes the gas (heating with 30  000 Kelvin S) using Radio frequency S emitted in an axial magnetic field (radiation Hélicon exciting the electron S).
# plasma is confined remotely of the wall by Solénoïde S surrounding the cylindrical room, creating an axial magnetic field in the enclosure.
# a " ICRH" antenna; ( Ion Resonant Cyclotron Heating ) completely ionizes plasma while bringing it up to very high temperature (10 megakelvins) and generates an induced electric field which accelerates the ions in a helicoid trajectory towards the exit. It is the principal booster rocket .
# a " conduit magnétique" at exit the jet of plasma controls by modelling the trajectory of the ions axially.

This conduit with " magnetic geometry variable" , makes it possible to vary the impulse specific and the push to constant power , by modulating the intensity of the magnetic field and the geometry of its lines of field. An analogy consists in comparing this magnetic conduit to the Gear box of a Automobile, whose Moteur would be fed in Combustible with constant mode.

Current and future research

The theoretical concept of VASIMR was invented at the end of the years 1970 by the Astronaute and Physicien of the plasmas Franklin Chang-Díaz, which initially studied it with the Charles Stark Draper Laboratory then with the Plasma Fusion Center of MIT (Massachusetts Institute off Technology) and finally with the ASPL ( Advanced Space Propulsion Laboratory ) founded for this purpose in December 1993 with the Johnson Space Center of NASA, which holds an experimental prototype.

Multiple universities and organizations contribute to program VASIMR, in addition to NASA: MIT, the University from Texas in Austin, the National laboratory of Los Alamos, the Marshall Space Flight Center, the University Rice, the University of Houston, the University of Michigan, the National laboratory of Oak Ridge. In order to accelerate the development and the marketing of engines VASIMR, the pr. Chang-Díaz created in 2006, with the support of NASA and of all these organizations, the company AD Astra Rocket , father of the project. based with Houston in the USA and Guanacaste with the Costa Rica.

In 2007, a new prototype will be built to Costa Rica, and of the experimentation on board the International space station are programmed for 2010 and 2011. The first industrial achievements must produce specific impulses of 1  000 with 30  000 seconds (going correspondent at speeds of ejection from 10 to 300 km/s), and of pushed from 10 to 500 newtons. Although very great pushes can potentially be reached with VASIMR, the important weight of the systems of ionization and containment of plasma seems to have to prevent its use where a ratio power/high weight is necessary, for example for takeoff from the planet surface, zone of strong Gravité. Progress in this field is nevertheless fast, with a reduction in the mass of the electromagnet S of a factor 30 since the first experiments, thanks to superconductors at high critical temperature.

The radio waves and the magnetic fields are provided by an electric energy source of a few hundred kilowatts for the prototypes, ideally of several megawatts for an interplanetary vessel. This energy source would be the Nuclear fission today. With the improvement of these compact energy sources, it is planned to replace the light propellents which are hydrogen or helium by a denser plasma of Argon or of Xénon (a vessel of 20 tons, supplying an engine VASIMR with 200 MW, would return Mars at only 39 days of voyage of the Ground). By widening this idea and although that is not realistic short-term, it is also theoretically possible that concept VASIMR can one day be articulated around a plasma of fusion constituting itself the propelling one. The caloric intake of fusion, and thus the push, would be in this case much higher compared to an electric or electromagnetic heating.

See too

Related articles

External bonds

  • Mars: The engines of the voyage by Richard Heidmann on Futura-Sciences.com
  • space science and Mars should off triumph over the sudden starts of the American situation
  • Propulsion Systems the Future over the site of NASA
  • ASPL ( Advanced Space Propulsion Laboratory ) over the Web site of NASA
  • AD Astra Rocket

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