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A blog to study the future you have never seen before
There, ” 0.0085 N thrust was measured without plasma injection, plasmamass injection ..”
Hayabusa generated plasma by irradiating xenon with microwaves, but I was wondering how the plasma was generated in this experiment.
I tried loading. There are strings of characters that I have never heard of, such as “magnetosphere expansion method using plasma flow” and “MPD arc jet”.
Here, let’s look at a schematic diagram of the device. If you look closely, there is something called “H2 Gas Tank”.
By the way, Wikipedia’s “MPD arc jet” page states that “The main propellant is Argon, Hydrogen, Hydrazine etc.”
I was talking about magnetic sails, but MPD arcjets about ion engines came up.
Plasma generation in magnetic sails
Imagine a satellite with magnetic propulsion.
I know how to create a magnetic field using an electromagnet and expand it with plasma.
But how do you create and blast the plasma?
I also looked into this. I couldn’t find anything in Japanese, so I googled “magnetic sailing mechanics” and found the figure below.
Among them, there was a string called “Electrodeless Plasma Electromagnetic Acceleration Method”.
Electrothermal acceleration, electrostatic acceleration, and electromagnetic acceleration are conceivable as methods for accelerating plasma. The most efficient method is to use an isentropic process with a single acceleration process static. Electrostatic acceleration (acceleration of charged particles without collision due to potential difference).
(Omitted)
In “Lissajous” acceleration, the plasma is rotated by an RF orthogonal electric field with an angular frequency ˙ that is 90° out of phase, similar to the two-dimensional motion of the electron beam spot by the deflection plate of a CRT (Cathode Ray Tube). Consider slowing down.
(Omitted)
If the angular frequency ˙ of the rotating electric field is chosen appropriately, the inertial mass is too large to follow the ions (pseudo-Larmor radius R is very small), but the electrons can follow (pseudo-Larmor radius R ≅ 1 cm order). can create
At this time, since only the circumferential electron current remains, the plasma is accelerated by the principle of Hall acceleration.
That’s right.
I will also quote from the paper “Electrodeless Acceleration and Characterization of High Density Helicon Plasma”.
A rotating magnetic field 𝐵ω is generated by applying currents with a phase difference of 90 degrees to a pair of opposing coils.
By setting the rotation angular frequency 𝜔 of the magnetic field as 𝜔ci < 𝜔 <
where 𝜔ci is the ion cyclotron angular frequency [rad/s], 𝜔ce is the electron cyclotron angular frequency [rad/s]. An axial Lorentz force 𝐹Z = 𝑗θ 𝐵𝑟 is generated in the cross product direction of the circumferential current 𝑗θ and the radial component 𝐵r of the externally applied divergent magnetic field, and the plasma can be accelerated . >
Since I could only find these two when I searched, I will try to clarify as it is.
First, we pay attention to the description that “a rotating magnetic field 𝐵ω is generated by applying currents with a phase difference of 90 degrees to a pair of opposing coils.”
What comes out here is the knowledge of AC circuits.
For some reason, it seems that When AC current is passed through the coil, the phase shifts by 90 degrees .
There is also a rotating magnetic field or rotating magnetic field.
At least, it is true that “uses the magnetic field generated when current is applied to the coil to generate the Lorentz force in the direction of the nozzle”.
After hours and dozens of sites, I couldn’t figure it out…
For now, let’s stop talking about “shooting plasma” here. Let’s get back to the topic.
Think about why the expanded magnetic field receives the solar wind and advances.
The reason why the solar wind can be accelerated by receiving it in a magnetic field
When an object is placed in a uniform flow, the flow is slowed down by resistance. At this time, according to the law of action and reaction, a corresponding force acts on the object, and in the case of a sailing ship, this force is used as thrust. The magnetic field created in outer space acts as a wall, and the lost momentum is transmitted to the spacecraft as the solar wind slows down (Fig.①). This theory is the basic concept of magnetic sails.
In the case of a magnetic sail, the pressure distribution acts on the interface called the magnetospheric boundary, which exists between the magnetic field and the solar wind plasma flow, and a corresponding interface current flows. The magnetic field induced by this induced current generates a Lorentzian force of j X B with the coil current, but the direction of the coil current is opposite in front (day side) and behind (night side) when viewed from the center of the coil. Therefore, it can be seen that the Lorentz force is generated in opposite directions (Fig.②). However, considering that the front coil current is closer to the magnetospheric boundary current, the magnetic field induced at the front coil position is larger than the rear coil position, and the magnitude relationship of Lorentzka can be written as follows. .
Thus, the magnetic sail is always forced away from the sun, in the same direction as the solar wind. And this becomes the thrust.
Positively charged interplanetary space to explain the principle of electrostatic sails
(Omitted)
The emission of negative charges (electrons) causes the spacecraft to This is because when the spacecraft is positively charged, an electric field (E) directed outward from the spacecraft is generated. Positive ions (charge q) approaching the spacecraft are bounced back by the Coulombqua (F = qE).
As a result, the reaction force of the repulsive force received by the positive ions acts on the spacecraft, and the thrust for accelerating the spacecraft is obtained. ．
From what I’ve researched, it seems that charged particles have the property of being able to change course when they pass through a magnetic field.
Positive ions of the plasma contained in the solar wind are bounced off the deployed magnetic field.
The reaction force is used.
Summary
Because I got too deep into it, I got stuck in a hole.
I’ll come back when I have a better understanding of the laws of physics.
