ORIGINAL ARTICLE AT: http://jlopez2022.wordpress.com/2014/05/15/2014-may-multimegawatt-plasma-thrusters-pulsotron-2-test-report/

Javier Luis López Segura,
Jorge Juan López,
Judy Atkins
Pulsotrón SL

Abstract.-
Cuenca, in the May 2014 test campaign not only ion-heating plasma thrusters were tested but also various new electrodeless magnetic neutral beam plasma thrusters.
The average injected power ranges from 20 to 120 megawatts.
New plasma diagnostics specialized to measure the new devices were also tested.

Table of contents
1. New electrodeless plasma thrusters design.-
2. Equations
3. Test results.-
4. Drawbacks
5. Conclusions.-
6. References.-
7. Some high speed video captures.-

1. New electrodeless plasma thrusters design.-

The new plasma thrusters are electrodeless in order to avoid the great erosion from plasma that was observed in the April test campaign.

Three short plasma thrusters and one long one were built over a thick copper protection material in order to anticipate the high plasma pressure.
2. Equations
In the next figure, the magnetic field at a distance D and an angle θ is:

–see at wordpress —

M=magnetic moment
N=number of turns

BD=B*cos(θ)
Bθ=B*sin(θ)

The magnetic field in the axle of a long coil of length “L” corresponds to θ=0, then if we integrate in the centre of the coil from D= -L/2 to L/2 we obtain:

Where r is the internal radius.
All variables according to International System of Units.
3. Test results.-
The first 4 tests were calibration tests that were performed mainly in order to adjust the diagnostics and oscilloscope scale.
PT2,3 and 8 are old ion heating Plasma thrusters
PTC-1,2,3 are new electrodeless magnetic plasma thrusters
PTB-1 is a modified magnetic plasma thruster that uses a variable magnetic coil that moves the magnetic field accompanying the plasma wave

Device Average current (kA) Average power (MW) Injected energy

–see attached figure —

The following columns represent:
1. Column 1 represents the average current injected
2. Megawatts injected
3. Percentage of the injected energy. The percentage of energy not injected does not signify losses but means a lesser power thrust.
4. Radiation losses due to Bremsstrahlung radiation
5. Energy efficiency: Obtained by substraction of the losses from injected energy.
6. Relation of speed of particles measured with respect to the maximum theoretical speed. The values are low due to the fact that the test was performed at atmospheric pressure. The results obtained are approximate due to the problems we had with the diagnostics as is said in the Drawback chapter.
7. The last column represents the average internal magnetic field during energy injection test. This column does not affect the tests on plasma thrusters without magnetic compression nor the calibration tests.

Some particles reached 1.2 million metres per second as can be seen in the following plan, reaching in the second probe at a distance of 25mm from the first one in only 13 nanoseconds.

4. Drawbacks
Diagnostics failed to measure the particle speed with acceptable accuracy due mainly to wrong grounding of the test probes and the great electromagnetic noise. It is clear that the diagnostics methods used before do not work properly in the new plasma thrusters.

5. Conclusions.-
The new electrodeless magnetic thrusters are much more efficient than the ion heating ones, thanks to the fact that they have less losses due to radiation and can also be used for much longer periods of time as the magnetic field prevents the nozzle erosion by plasma particles.