Extraction Electrode Pulsing for Higher Charged Particle Beam Pulses
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Solution Overview
Problem
Existing charged particle guns, such as those used in electron microscopes, face limitations in the number of charged particles emitted per pulse due to the method of pulsing the electron beam using a blanker.
Innovation Solution
A charged particle gun design that includes an emitter, an extraction electrode, a capacitor, and power supplies to vary the voltage applied to the extraction electrode in a pulsed manner, increasing the number of charged particles per pulse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a blanker is used to pulse the electron beam, then the electron beam can be emitted in pulses, but the number of charged particles in each pulse is limited
Solution Approach 1:
The invention changes the voltage parameter applied to the extraction electrode in a pulsed manner. By varying the extraction voltage dynamically using a capacitor charged by power supplies and controlled by a switch circuit, the emission current is increased during pulse periods, thereby increasing the number of charged particles per pulse without requiring a fundamentally different device architecture
Solution Approach 2:
The invention introduces dynamic control of the extraction electrode voltage through a switch circuit that alternates between charging the capacitor and discharging it to ground. This dynamic voltage modulation allows the emission current to be varied in response to pulse signals, enabling higher particle counts per pulse while maintaining device simplicity
2Quantity of substance
If the emission current is increased to emit more charged particles per pulse, then the number of charged particles increases, but the electrodes are irradiated for longer periods and gas production increases
Solution Approach 1:
The invention employs periodic pulsed operation where the extraction voltage is applied in discrete pulses rather than continuously. The switch circuit charges the capacitor during off-periods and discharges it during pulse-periods, creating a periodic emission pattern that delivers high particle counts in short bursts, thereby reducing total irradiation time and gas production
Solution Approach 2:
The capacitor maintains the elevated extraction voltage throughout the pulse duration, ensuring continuous emission of charged particles at high current during the pulse period. This eliminates gaps in the emission that would occur with blanking methods, maximizing particle delivery efficiency within the pulse window
3Quantity of substance
If the emission current is increased to emit more charged particles per pulse, then the number of charged particles increases, but the emitter temperature rises
Solution Approach 1:
The periodic pulsed operation allows the emitter to experience high emission current only during brief pulse intervals, followed by cooling periods when the voltage is reduced or zero. This duty-cycle-based approach enables high particle counts per pulse while providing thermal management through intermittent operation, preventing excessive temperature accumulation
Solution Approach 2:
The capacitor is charged in advance during the off-period before each pulse, preparing the extraction voltage in advance. This preliminary charging action allows the full extraction voltage to be applied instantaneously at pulse onset, maximizing emission current without requiring sustained high power that would overheat the emitter
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 allows for an increased number of charged particles in each pulse, reducing the time electrodes are irradiated and minimizing gas production and emitter temperature rises.
Implementation Method 1
a capacitor having one end connected to the extraction electrode; a first power supply for supplying a first voltage to the one end of the capacitor via a resistor
Implementation Method 2
an emitter; an extraction electrode for extracting the charged particle beam from the emitter
Implementation Method 3
an emitter; an extraction electrode for extracting the charged particle beam from the emitter
Data Source
AI summary
There is provided a charged particle gun capable of increasing the number of charged particles contained in each pulse. The charged particle gun operates to emit a charged particle beam and includes: an emitter, an extraction electrode for extracting the charged particle beam from the emitter, a capacitor having one end connected to the extraction electrode, an offset power supply for supplying a first voltage to the one end of the capacitor via a resistor, a pulsed power supply providing an output of a second voltage, and a switch circuit that switches between whether the second voltage or a reference potential is supplied to the other end of the capacitor, based on a reference pulsed signal.