Performance degradation mechanism of a helicon plasma thruster

May 13, 2015, Tohoku University
(a) Photograph of the helicon plasma thruster at Tohoku University. (b) The measured plasma pressure profile and the particle dynamics relating to the loss of axial momentum loss. Credit: Kazunori Takahashi

A part of the performance degradation mechanism of the advanced, electrodeless, helicon plasma thruster with a magnetic nozzle, has been revealed by the research group of Dr. Kazunori Takahashi and Prof. Akira Ando at Tohoku University's Department of Electrical Engineering.

An device is a main engine, and a key piece of technology for space development and exploration. Charged particles are produced by electric discharge and accelerated, i.e. is transferred to them via electromagnetic fields. The thrust force is equivalent to the momentum exhausted by the device, and the spacecraft can thus be propelled into space.

Mature electric propulsion devices such as ion engines, hall thrusters and magnetoplasmadynamic thrusters have electrodes exposed to the plasmas. Ion sputtering and erosion damage these exposed electrodes over time. For propulsion systems that are used over a long period, electrodeless propulsion devices have been suggested and rigorously researched as an alternative option. These are represented by the Variable Specific Impulse Magneto- Rocket (VASIMR) and the helicon .

In the helicon plasma thruster concept, the charged particles in a high density helicon plasma source is guided to the open source exit and accelerated by the magnetic nozzle via a magnetic expansion process. Various gain and loss processes of the particle momentum occur in the thruster, significantly affecting the propulsive performance, where the thrust force is equivalent to the momentum exhausted from the system.

It has been considered that the major momentum loss occurs at the source lateral wall, where the "radial" momentum is transferred to the wall via an electrostatic ion acceleration in the plasma sheath. This might be true. Although the loss of the axial momentum there has been treated as negligible, data from experiments clearly show the presence of the "axial" momentum lost to the lateral wall, which is transferred by the radially lost ions.

This significant axial momentum loss seems to have originated from the internal axial electric field in the plasma core, which appears to be more enhanced by the highly ionized plasmas for the future high power operation of the helicon plasma thruster. More detailed understanding of the plasma dynamics will hopefully lead to further development of the advanced high power and electrodeless electric propulsion device.

The detailed observations of the momentum loss will be published by the American Physical Society in their journal Physical Review Letters on May 8.

Explore further: Image: Solar Electric Propulsion engine's ionizing Hall thruster

Related Stories

Magnetic shielding of ion beam thruster walls

February 13, 2013

Electric rocket engines known as Hall thrusters, which use a super high-velocity stream of ions to propel a spacecraft in space, have been used successfully onboard many missions for half a century. Erosion of the discharge ...

The revolutionary ion engine that took spacecraft to Ceres

March 9, 2015

The NASA spacecraft Dawn has spent more than seven years travelling across the Solar System to intercept the asteroid Vesta and the dwarf planet Ceres. Now in orbit around Ceres, the probe has returned the first images and ...

Recommended for you

A new experiment to understand dark matter

June 15, 2018

Is dark matter a source of a yet unknown force in addition to gravity? The mysterious dark matter is little understood and trying to understand its properties is an important challenge in modern physics and astrophysics. ...

Quantum transfer at the push of a button

June 15, 2018

In new quantum information technologies, fragile quantum states have to be transferred between distant quantum bits. Researchers at ETH have now realized such a quantum transmission between two solid-state qubits at the push ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.