Optical Plasma Magnetic Field Measurement With Adjustable Sensitivity
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Solution Overview
Problem
Existing magnetic field measurement methods for plasmas face challenges such as probe interference, cooling, and high temperature ablation, while non-contact methods like Faraday rotation require precise electron density knowledge, leading to measurement errors.
Innovation Solution
An optical measuring device and method using a pulsed laser, beam splitters, polarization analyzers, and cameras to measure optical rotation and interference images, allowing adjustable sensitivity through beam splitter ratios and polarization angles, enabling accurate determination of magnetic field distributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a contact magnetic induction coil is used to measure plasma magnetic field, then the measurement principle is simple and cost is low, but the probe cools the plasma and disturbs the movement process while induced current interferes with the plasma magnetic field
Solution Approach 1:
The patent replaces the mechanical contact magnetic induction coil with a non-contact optical measurement system using polarized light and Faraday rotation effect. The light beam passes through the plasma without physical contact, eliminating probe cooling and plasma disturbance while still measuring magnetic field distribution through optical rotation angle changes.
Solution Approach 2:
The patent introduces light as an intermediary medium to measure the plasma magnetic field indirectly. Instead of direct contact between the probe and plasma, the polarized light interacts with the plasma's magnetic field through Faraday rotation, allowing measurement without the harmful effects of direct probe insertion.
2Ease of manufacture
If a contact magnetic induction coil is used to measure plasma magnetic field, then the measurement principle is simple and cost is low, but the coating on the magnetic probe will be ablated at high temperature and measurement signal may exceed measurable threshold
Solution Approach 1:
The patent replaces the vulnerable mechanical probe with an optical measurement system. The light beam can withstand high plasma temperatures without ablation, and the optical components remain outside the high-temperature zone, ensuring reliable measurement signal detection without the limitations of contact probe durability.
3Object-affected harmful factors
If non-contact Faraday rotation method is used to measure plasma magnetic field, then probe interference is eliminated, but the method requires precise electron density knowledge which leads to large measurement errors
Solution Approach 1:
The patent employs feedback mechanisms where the optical rotation angle measurements are used to iteratively refine both electron density and magnetic field calculations. By using the measured rotation angles to update the model parameters and recalculate, the system reduces measurement errors and achieves higher precision in magnetic field determination without requiring prior precise electron density knowledge.
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
The method provides efficient and reliable measurement of plasma magnetic fields with adjustable sensitivity, overcoming probe interference and environmental constraints, and reducing measurement errors.
Implementation Method 1
When a beam of linearly polarized light passes through a plasma, it will deflect, and the rotation angle is related to the electron density and magnetic field distribution on the light propagation path
Implementation Method 2
a first beam splitter, a second beam splitter, a third beam splitter, a fourth beam splitter
Implementation Method 3
a first polarization analyzer, a second polarization analyzer
Implementation Method 4
a first camera, a second camera, a third camera and a fourth camera
Implementation Method 5
constructing an interference measurement system based on the pulsed laser beam, and measuring a phase shift of an interference image
Data Source
AI summary
The present disclosure discloses an optical measurement device and method for a plasma magnetic field with adjustable sensitivity. The method comprises the following steps: constructing an optical rotation measurement system based on a pulsed laser beam for measuring an optical rotation image and a shadow image; processing the optical rotation image and the shadow image, and obtaining a distribution of proportional coefficients based on alight intensity distribution; obtaining a distribution of rotation angles based on a mapping relationship between the proportional coefficients and the rotation angles; constructing an interference measurement system based on the pulsed laser beam, and measuring a phase shift of an interference image; calculating a distribution of electron areal densities based on the phase shift in the interference image; obtaining a two-dimensional distribution of an average magnetic field based on the rotation angles and the electron areal densities.