Magnetic Lens Current Control for Thermal Equilibrium in Charged Particle Beam Apparatus
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Solution Overview
Problem
Conventional magnetic lenses in charged particle beam apparatuses consume unnecessary power and prolong the time needed to reach thermal equilibrium when operated at low acceleration voltages, as they maintain constant thermal power consumption, leading to excessive heat generation and drift standby times.
Innovation Solution
A charged particle beam apparatus with a magnetic lens featuring a setting unit to define a maximum current value based on user operation and a current control unit to regulate the current within a specific range, maintaining constant thermal power consumption, thereby reducing power wastage and shortening thermal equilibrium time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the current supplied to the auxiliary coils is controlled to maintain thermal power consumption corresponding to maximum magnetomotive force, then thermal stability is maintained, but unnecessary power is consumed when operating at low acceleration voltage
Solution Approach 1:
The patent applies dynamics by making the current control strategy adaptive rather than static. The control unit dynamically adjusts the current supplied to auxiliary coils based on the actual acceleration voltage being used. When operating at low acceleration voltage, the current is reduced proportionally, while maintaining constant thermal power consumption only when needed for thermal stability. This dynamic adjustment resolves the contradiction between maintaining thermal stability and reducing unnecessary power consumption.
2Stability of the object's composition
If constant thermal power consumption is maintained in the electromagnetic coil, then temperature stability is achieved, but the time required to reach thermal equilibrium increases
Solution Approach 1:
The patent applies periodic action by implementing a time-based control strategy. During the initial warm-up period, the current control unit supplies reduced current to the auxiliary coils, allowing the system to reach thermal equilibrium faster. Once thermal equilibrium is achieved, the control unit maintains constant thermal power consumption to ensure temperature stability during operation. This periodic switching between different control modes resolves the contradiction between reducing drift standby time and maintaining temperature stability.
3Measurement precision
If the magnetic lens is operated at low acceleration voltage, then surface information detection capability is improved, but the necessary magnetomotive force decreases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the current parameter supplied to the auxiliary coils based on the acceleration voltage parameter. When the acceleration voltage is reduced to improve surface information detection capability, the control unit proportionally reduces the current to the auxiliary coils, thereby reducing the magnetomotive force to match the lower electron beam energy. This parameter coordination resolves the contradiction between improving measurement precision and reducing power requirements.
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 configuration minimizes unnecessary power consumption and reduces the time required to reach thermal equilibrium by controlling current supply to the magnetic lens coils, optimizing thermal stability and reducing drift standby times.
Implementation Method 1
a magnetic lens having an electromagnetic coil composed of a pair of coils
Implementation Method 2
joule heat causes the temperature of the coil to rise
Data Source
AI summary
A charged particle beam apparatus that includes a magnetic lens having an electromagnetic coil composed of a pair of coils includes: a setting unit that sets a maximum current value that defines a maximum magnetomotive force of the magnetic lens based on an operation of a user; and a current control unit that controls a current to be supplied to each of the pair of coils within a current range corresponding to a set maximum current value so that thermal power consumed by the electromagnetic coil is maintained constant at thermal power corresponding to the set maximum current value.