For long-term work in space, reliable electric rocket engines with a plasma flow velocity of the order of one hundred and five meters per second or more should be used. Plasma engines began to be actively developed in the middle of the last century. And today this work continues.
Start research
Our ancestors have long wanted to fly into space. For a long time, gas has been actively studied using an electric discharge. It was placed in a glass container with electrodes. Then, when the pressure was reduced, rays emanating from the cathode appeared, which in fact, as it was later found out, was a stream of electrons.
And in 1886 it was discovered that, while making holes in the cathode, other rays, ionized atoms of gases, stretched in the opposite direction from them. But then, of course, they had no idea that they would be used to obtain jet thrust.
In the days of the Soviet Union, ion and plasma thrusters were developed in the laboratories of the Physics and Technology SOAN to apply these technologies in vehicles for space flight. Work started in the 1950stwentieth century. Two types of devices have been opened:
- erosive engine (impulse);
- stationary plasma thruster (non-pulsed).
It is these two types that are used to this day.
Erosive and stationary
The plasma engine that is known today operates due to the reactive force of the plasma jet from the nozzle. The plasma itself is formed by means of an electric discharge. For a simpler motor power source, a pulsed mode (erosive plasma engine) is selected. The energy source is a capacitor with a capacitance of 0.5 microfarads and a voltage of 10 kV. It is charged from the transformer with diodes and a resistor.
With the help of such devices, small and precise impulse thrusts are formed, which cannot be obtained with the operation of other types of rocket motors. Pulsed plasma thrusters were successfully tested in 1964 on the Zond-2 space station.
SPD is a variant of an accelerator in an extended zone and with a closed drift of electrons. Such devices can work for a long period of time. Two xenon engines were first launched in 1972 aboard the Soviet Meteor.
Operating principle: prototype
The installation works as follows. The voltage for the capacitor is the gap between the current-conducting collector and the electrodes of the discharge chamber. When the voltage reaches the breakdown value, an electric discharge appears in the engine chamber. The air there is heated toten thousand units and acquires a plasma state. The pressure sharply increases, and the plasma jet flows out of the nozzle with great speed.
The rocket, which is connected to the engine, receives jet power from the jet. To achieve a soft rotation, the rocket is attached with a ball bearing and balanced by a counterweight.
The most complex electrical unit is a collector that supplies current. The gaps between the electrodes should be no more than half a millimeter. Then there will be almost no power loss from the capacitor, and no additional friction will be generated when the rocket starts to spin.
The rocket itself and the entire plasma rocket engine can have different sizes, but the power of the source and the size of the capacitor must be matched. To calculate the basic units and rocket design, it is convenient to use the scheme after calculation by special formulas.
Experimental values on the example
On the example with a given voltage of six thousand watts and a capacitor capacitance of 0.510 (-6) f, as a result of calculations, the energy that is released in the engine chamber is 5.4 J. And if the temperature difference is 10000K, then the volume of the chamber will be equal to half a cubic centimeter.
Then the elements of the electrical circuit will be:
- transformer 2205000V, having a power of 200 watts;
- wire resistor with a power of 100 watts.
This model has an operating voltage of more than a thousand volts, and therefore must bebe very careful when working with it and observe all necessary safety rules.
Safety rules for the experiment
- The launch is carried out by one person. Others may stand at a distance of one meter from the device.
- All operations and touching of the unit by hand can only be done if it is disconnected from the power supply, after waiting at least a minute after that. Then the capacitor will have time to discharge.
- The power supply must be located in a metal case, closed on all sides. During operation, it is grounded by means of a copper wire, the diameter of which must be at least one and a half millimeters.
Plasma thrusters for real rockets must be several thousand times more powerful! Maybe those who conduct experiments with small samples today will discover new possibilities and properties of plasma tomorrow.
