Plasma jet engines that could take you from the ground to space

FORGET fuel-powered jet engines. We’re on the verge of having aircraft that can fly from the ground up to the edge of space using air and electricity alone.

Traditional jet engines create thrust by mixing compressed air with fuel and igniting it. The burning mixture expands rapidly and is blasted out of the back of the engine, pushing it forwards.

more…

Tau.Neutrino said:

Plasma jet engines that could take you from the ground to space

FORGET fuel-powered jet engines. We’re on the verge of having aircraft that can fly from the ground up to the edge of space using air and electricity alone.

Traditional jet engines create thrust by mixing compressed air with fuel and igniting it. The burning mixture expands rapidly and is blasted out of the back of the engine, pushing it forwards.

more…

Just like Grant’s design on Mythbusters. I’d be interested in seeing engineering calculations for this. Power vs lift.

Slight change of topic, but still plasma propulsion.

https://www.sciencedaily.com/releases/2017/05/170523124203.htm

Neptune: Neutralizer-free plasma propulsion.

Plasma propulsion systems use electric power to ionize propellant gas and transform it into the fourth state of matter, known as plasma. Electrically charged ions and electrons are accelerated in an exhaust beam to generate thrust and propel the spacecraft.

The most established electric propulsion concepts, for example gridded-ion thrusters, accelerate and emit a larger number of positively charged particles than those with negative charge. To enable the spacecraft to remain charge-neutral, a “neutralizer” is used to inject electrons to exactly balance the positive ion charge in the exhaust beam. However, the neutralizer requires additional power from the spacecraft and increases the size and weight of the propulsion system.

A team from the University of York and École Polytechnique is investigating how the neutralizer can be removed altogether.

Looks promising. Making plasma drives that use significantly less overall power. I don’t see how they can do it, though.

The first proof-of-concept of a neutralizer-free gridded thruster called NEPTUNE which emits simultaneously ions and electrons producing thrust and high Isp is presented. The NEPTUNE prototype is built and tested in a 1m long beam propagation chamber. A broad quasi-neutral ion-electron beam with the ion energy up to 400 eV is successfully generated without the use of a neutralizer. This is achieved by the possibility of an efficient DC self-bias generation within the RF-powered multi-grid extraction system, which is in contact with plasma. A single RF power source is used for the gas ionization, ion acceleration and electron extraction; the NEPTUNE thruster prototype is therefore free of any additional DC power supplies. The beam extraction is investigated by measuring the ion and electron energies, fluxes and densities using a retarding field energy analyzer (RFEA) and different electrostatic probes. Comparison of the main beam parameters and efficiencies of the NEPTUNE source with a traditional gridded source equipped with a neutralizer is presented. It is concluded that the NEPTUNE concept allows generating a well-localized self-compensated broad ion-electron beam with same thrust efficiency as traditional gridded ion thrusters.

Neutralizer-free gridded ion thruster. Available from: https://www.researchgate.net/publication/269207885_Neutralizer-free_gridded_ion_thruster .

Finally, a paper that’s more easy to understand about the plasma drive without a neutralizer.

http://iopscience.iop.org/article/10.1088/0963-0252/25/4/043001

Electric propulsion systems have usually two common features: propellant ionization and ion acceleration. Most of the space-proven technologies use a plasma discharges for the propellant ionization and electrostatic field for the ion acceleration. Some new concepts apply a direct plasma-free ion emission from liquid metals and have been successfully tested. These devices have small dimensions and mass, do not require neutralizer and external fuel tank, and already reached high technology readiness level. Nevertheless, in this work we constrain ourselves to consider only plasma-based electric propulsion systems, and we refer to them below as ‘plasma propulsion’ systems.

Figure 2 shows an illustration of the different techniques that can be used to achieve a neutralizer-free acceleration. We separate the systems into three subgroups via the acceleration method: (i) neutral beam generation, (ii) plasma acceleration and (iii) bipolar beam acceleration. Below we consider these groups separately.

A Neutral beam thruster prototype called CXT (‘charge exchange thruster’) has recently been developed and tested at the University of Sydney.
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In general, quasi-neutral plasmas can be accelerated as a whole from a source using various physical mechanisms such as high intensity laser radiation, constant and pulsed electrical fields, electrodynamics effects, magnetic nozzles. Two common principles of plasma acceleration that can be used in space applications: J  ×  B acceleration (a) and acceleration by ambipolar field (b).
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pulsed plasma thruster (PPT). The PPT was the first electric propulsion system ever sent to space onboard the soviet spacecraft Zond 2 in 1964. The PPTs are commercialized and currently operated on a few spacecrafts. A vacuum arc thruster (VAT) is a concept similar to PPT but promises higher efficiency while keeping the main advantages. In a VAT system, the vacuum arc is ignited between two metal electrodes.
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quasi-neutral plasma. The propellant ionization and plasma heating can be achieved by using microwave electron cyclotron resonant discharge (coaxial electron cyclotron resonance (ECR) thruster.

Etc.