All said and done, the research team is not resting yet; they have studied certain mechanics by testing the PPS-Flex version of the hall thruster, and now getting set to design a more functional and promising hall thruster that is based on wall-less architecture.
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French scientist working with Hall thrusters – an advanced type of engine that harnesses a stream of plasma to generate forward momentum – have recently figured out a way to optimize these drives, allowing them to run on a staggering (wait for it) 100 million times less fuel than conventional chemical rockets.
Now researchers have adapted these electric rocket thrusters so they have the potential to power an entire voyage. Now, though, researchers are taking a closer look at these engines for deep space missions. The only problem for now is that while most space exploration missions require a minimum of 50,000 operation hours, hall thrusters for now has only 10,000.
In an experiment described in the latest issue of the journal Applied Physics Letters, researchers from the French National Centre for Scientific Research modified an existing wall-less thruster to improve its performance.
The engine, known as a “hall thruster”, is now being used by Nasa to keep satellites and space probes in the right orbit. Their operating principle relies on the creation of a low-pressure quasi-neutral plasma discharge in a crossed magnetic and electric field configuration.
This is because, unlike traditional ion drives, Hall thrusters do not have a physical cathode: they utilize a magnetic field and a trapped electron cloud that serve as a hollow, “virtual” cathode.
In the conventional Hall thruster configuration, the magnetized discharge is confined to an annular dielectric cavity with the anode at one end, where the gas is injected, and an external cathode injecting electrons. Ionisation of the propellant gas occurs inside the cavity, with ions accelerated by the electric field that stretches from the interior to the exterior of the cavity.
In a study issued in the journal Applied Physics Letters, experts from the French National Center for Scientific Research explained that they had enhanced the features of a wall-less Hall thruster prototype which the team created in 2014. This container, called the discharge channel wall, is being constantly bombarded with high-energy ions, and this wears it down so much, the whole engine will eventually need to be recalled to have the wall repaired or replaced.
“The major drawback of Hall thrusters is that the discharge channel wall materials largely determine the discharge properties, and consequently, the performance level and the operational time”, said Julien Vaudolon, one of the researchers, in a news release.
“The red anode should be lined up on the wall emitting xenon”.
In this case, though, the researchers have based a small-scale, wall-less thruster prototype based on a classical Hall thruster.
All of this is fine and works great, but the part of the Hall thruster that contains the anode, virtual cathode, and electron cloud is what’s holding it back. “Basically an electron travels along the magnetic field line”. The magnetic field lines intercept the anode. This creates a low-pressure plasma discharge, which produces thrust in the opposite direction from that of the ion flow.
In their first attempt, however, the performance of the small-scale thruster was low. However, Vaudolon said, a few further optimization is still needed for the thruster’s efficient operation at high power.
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‘The wall-less thruster allows scientists to observe regions of the plasma previously hidden behind the channel walls, ‘ Vaudolon said.
