Plasma Generation Apparatus with Dual Electron Density Measurement
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Solution Overview
Problem
Existing plasma generation apparatuses face challenges in quantitatively measuring and controlling plasma conditions due to reliance on light from plasma, making it difficult to achieve stable and proper control of plasma conditions for plasma thrusters.
Innovation Solution
A plasma generation apparatus equipped with a measurement device that includes an emission spectra measurement device, a probe measurement device, and a control device to measure and control electron density by adjusting electric power, magnetic fields, and gas supply based on data from both devices, allowing for comprehensive and stable plasma condition management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If emission spectra measurement device is used to measure electron density, then measurement coverage can be achieved, but measurement precision is insufficient without absolute value calibration
Solution Approach 1:
A probe measurement device is introduced as an intermediary calibration tool to measure absolute electron density at specific positions. This probe serves as a mediator between the emission spectra measurement and true absolute values, enabling calibration of the optical measurement system to achieve both wide coverage and high precision.
Solution Approach 2:
The probe measurement device creates a reference copy of the absolute electron density value at a specific location. This reference value is then used to calibrate and correct the emission spectra measurement data, allowing the entire measurement area to be scaled to absolute values while maintaining the spatial distribution information.
2Measurement precision
If single measurement device is used, then device complexity is low, but measurement precision and control accuracy are insufficient
Solution Approach 1:
Two different measurement devices (emission spectra measurement device and probe measurement device) are merged into a unified measurement system. The emission spectra device provides spatial distribution data while the probe device provides absolute calibration data, and their combined results achieve both precision and comprehensive measurement capability.
Solution Approach 2:
The probe measurement device provides feedback on the absolute electron density values to the control device. This feedback loop enables the control device to adjust plasma generation conditions based on accurate measurements, improving control precision while the system manages the complexity through integrated control.
3Reliability
If plasma conditions are controlled based on relative values only, then control simplicity is maintained, but control accuracy and stability are insufficient
Solution Approach 1:
The control device receives feedback from both measurement devices and uses absolute electron density values to adjust plasma generation conditions. This feedback mechanism with absolute values significantly improves control stability and reliability, while the integrated control architecture manages system complexity.
Solution Approach 2:
The control device adjusts plasma generation parameters (power, gas flow, magnetic field) based on absolute electron density measurements. By controlling based on absolute values rather than relative changes, the system achieves more stable and predictable plasma conditions, improving reliability.
Data Source
AI summary
A plasma generation apparatus, and a plasma thruster configured to use the plasma generation apparatus are disclosed. The plasma generation apparatus includes a discharge vessel, a light-emitting monitor, a probe measuring instrument, a control device, and an optical axis driving unit. The discharge vessel is configured to ionize gas which is introduced to an inside thereof so as to generate plasma. The light-emitting monitor is configured to measure electron density of the plasma by emission spectra of the plasma. The probe measuring instrument is configured to measure the electron density of the plasma by a probe in the discharge vessel.