Plasma Generator Dual-Frequency Coil for Wall Loss Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional high-frequency plasma generators suffer from significant power loss due to ion and electron recombination on the walls of the ionization chamber, limiting the efficiency of ion thrusters and ion sources to only 5% to 20% electrical power conversion for thrust generation, with the remaining power converted into heat and radiation.
Innovation Solution
A plasma generator design that incorporates an additional current source or voltage source to supply a lower-frequency alternating current to the coil arrangement, creating a superimposed magnetic field that confines electrons and ions, reducing their movement towards the walls and enhancing their flow towards the extraction grid, thereby minimizing recombination losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high-frequency alternating current is supplied to the coil arrangement for plasma generation, then plasma is generated in the ionization chamber, but significant power loss occurs due to ion and electron recombination on the walls
Solution Approach 1:
The patent applies periodic action by superimposing a low-frequency alternating current component on the high-frequency alternating current supplied to the coil arrangement. This creates a time-varying magnetic field with dual frequency components that periodically modulates the electron confinement, reducing wall losses and improving power conversion efficiency from 5-20% to significantly higher levels.
Solution Approach 2:
The patent changes the electrical parameters by introducing a dual-frequency current supply system. The low-frequency component (superimposed on the high-frequency current) modifies the magnetic field characteristics, thereby changing the plasma confinement parameters and reducing recombination losses on the chamber walls.
2Quantity of substance
If only high-frequency alternating current is used, then plasma generation is achieved, but electron and ion movement towards the walls causes recombination losses
Solution Approach 1:
By superimposing a low-frequency alternating current component on the high-frequency current, the magnetic field exhibits periodic modulation at two frequencies. This periodic action creates dynamic electron confinement that reduces wall-directed motion, thereby reducing recombination losses and maintaining higher plasma density.
Solution Approach 2:
The dual-frequency current supply ensures continuous plasma generation with reduced interruptions. The low-frequency component continuously modulates the magnetic field to maintain electron confinement, ensuring continuous useful action of plasma generation while minimizing losses.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design reduces wall losses in ionization chambers, optimizes plasma homogeneity, and increases plasma density and electron flow, allowing for more efficient energy utilization and thrust generation without altering the basic design of existing ion sources or engines.
Implementation Method 1
A high-frequency alternating current flows through the coil. The alternating current creates an axial magnetic field inside the ionization chamber. This time-varying magnetic field induces a circular alternating electric field in the ionization chamber.
Implementation Method 2
This alternating electric field accelerates free electrons so that they can finally absorb the energy required for electron impact ionization. Atoms of the fuel are thereby ionized.
Implementation Method 3
The Lorentz force acts on moving charge carriers in the magnetic field with the charge q, the speed v and the magnetic flux density B. The proportion of the low-frequency alternating current superimposed on the high-frequency electromagnetic alternating field causes the charge carriers (electrons and ions) within the coil and thus within the ionization chamber to be forced into circular or spiral paths in the magnetic field.
Data Source
Figure 1
Figure 2~3
Figure 4~6
AI summary
The invention relates to a plasma generator comprising a housing (20) that surrounds an ionisation chamber (5); at least one working fluid supply line (30) leading into the ionisation chamber (5), said ionisation chamber (5) comprising at least one outlet (21); and at least one electric coil arrangement (4) that surrounds at least one area of the ionisation chamber (5); said coil arrangement (4) being electrically connected to a high-frequency alternating current source (AC) that is designed such that a high frequency electric alternating current is applied to at least one coil of the coil arrangement (4). Said plasma generator is characterised in that an additional current source (DC) is designed such that a DC current or an alternating voltage is applied at a lower frequency than the voltage supplied by the high frequency alternating current source (AC) to at least one coil of the coil arrangement (4), is provided.