Coordinated Clearing Gaps in FEL Radiation Sources
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Solution Overview
Problem
Free electron laser (FEL) radiation sources face ion build-up issues due to collisional ionization, leading to increased emittance and reduced conversion efficiency, particularly in extreme ultra-violet (EUV) radiation production, which existing strategies like clearing gaps only partially mitigate.
Innovation Solution
A timing pattern and path length design for electron bunches in FEL radiation sources, incorporating coordinated clearing gaps to allow ion clearance, ensuring these gaps overlap during acceleration and deceleration phases in multiple LINAC sections, maintaining energy recovery operation and reducing ion concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If clearing gaps are introduced to reduce ion build-up, then ion concentration is reduced, but energy recovery operation of LINACs is distorted
Solution Approach 1:
The patent implements periodic clearing gaps in the electron bunch sequence at strategically designed positions within the LINAC loop. These gaps are introduced at locations where they minimize disruption to the RF cavity fields, allowing ion clearance while preserving the overall periodic structure needed for energy recovery operation.
Solution Approach 2:
The patent pre-calculates and pre-positions clearing gaps at specific locations in the electron beam path where they will have minimal impact on LINAC operation. By placing gaps at predetermined positions before ions become problematic, the system proactively manages ion build-up while maintaining stable energy recovery.
2Object-affected harmful factors
If clearing gaps are placed in electron beam sequence, then ion clearance is enabled, but beam current pattern is disrupted
Solution Approach 1:
Instead of introducing frequent or long-duration clearing gaps that would significantly reduce beam current, the patent uses sparse, short-duration gaps that provide sufficient ion clearance while minimizing impact on overall beam productivity. The gap duration and frequency are optimized to achieve the minimum necessary ion removal.
Solution Approach 2:
The patent applies clearing gaps selectively at specific locations in the beam path where ion accumulation is most problematic, rather than uniformly throughout the entire beam sequence. This localized approach targets ion clearance where needed while preserving beam current continuity in other regions.
3Loss of energy
If multiple LINAC sections are used for acceleration and deceleration, then energy recovery is achieved, but clearing gap coordination becomes complex
Solution Approach 1:
The patent divides the electron beam path into distinct segments corresponding to different LINAC sections, with clearing gaps strategically placed in specific segments. This segmentation allows independent optimization of gap positioning in each section, simplifying the coordination complexity while maintaining energy recovery across all sections.
Solution Approach 2:
The patent introduces a timing coordination mechanism that acts as an intermediary between the multiple LINAC sections and the clearing gap generation. This mediator synchronizes the clearing gaps across different LINAC phases, managing the complexity of coordinating gaps through multiple acceleration and deceleration cycles.
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 coordinated clearing gap strategy effectively reduces ion build-up, maintaining efficient operation of FEL radiation sources by minimizing emittance growth and preserving energy recovery capabilities, thereby enhancing the stability and performance of EUV radiation production.
Implementation Method 1
ions are produced from residual gas in the electron beam through collisional ionization
Implementation Method 2
a plurality of linear accelerators (LINACs) for accelerating and decelerating the bunches of electrons
Implementation Method 3
an undulator configured such that in operation passage of the bunches of electrons through the undulator generates radiation at a desired wavelength
Data Source
AI summary
Passage through LINACs of electron bunches in their acceleration phase is coordinated with passage through the LINACs of electron bunches in their deceleration phase. Each successive pair of electron bunches are spaced in time by a respective bunch spacing, in accordance with a repeating electron bunch sequence. The electron source provides clearing gaps in the electron bunch sequence to allow clearing of ions at the undulator. The electron source provides the clearing gaps in accordance with a clearing gap sequence such that, for each of the plurality of energy recovery LINACS, and for substantially all of the clearing gaps: for each passage of the clearing gap through the LINAC in an acceleration phase or deceleration phase the clearing gap is coordinated with a further one of the clearing gaps passing through the LINAC in a deceleration phase or acceleration phase thereby to maintain energy recovery operation of the LINAC.