Laser-Produced Plasma Debris Mitigation via Multi-Pulse Conditioning
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Solution Overview
Problem
Existing laser-produced plasma devices face challenges in debris mitigation, stability, and conversion efficiency due to the limitations of single pre-pulse methods for generating electromagnetic radiation, particularly in producing small debris particles and maintaining long-term operation.
Innovation Solution
A method involving a pulse sequence of three or more conditioning laser pulses with time intervals of 200 ns or less, either before or after the main laser pulse, to shape the target and reduce debris size, while also improving conversion efficiency and protecting source optics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a single pre laser pulse is applied to the target, then debris particle size is reduced, but the repertoire of target shapes is limited and conversion efficiency is sub-optimal
Solution Approach 1:
The single pre-pulse is segmented into multiple conditioning pulses (at least three) within a pulse sequence, where each pulse contributes to progressive shaping of the target. This segmentation allows for more nuanced control over target morphology while maintaining debris mitigation benefits
Solution Approach 2:
A pulse sequence with specific time intervals (200 ns or less between pulses) creates periodic action that builds up the desired target shape through cumulative effects. The periodic application of energy allows for controlled material removal and shaping that a single pulse cannot achieve
2Object-generated harmful factors
If a single pre laser pulse is applied to the target, then some debris mitigation is achieved, but operation stability and conversion efficiency are sub-optimal
Solution Approach 1:
The pulse sequence performs preliminary shaping action before the main laser pulse, creating an optimized target geometry that enhances both debris mitigation and operational stability. The cumulative effect of multiple conditioning pulses prepares the target in advance for optimal interaction with the main pulse
Solution Approach 2:
Multiple parameters of the pulse sequence (number of pulses, time intervals, pulse energies) can be adjusted to optimize both debris mitigation and stability. The ability to vary these parameters provides flexibility in achieving stable operation under different conditions
3Object-generated harmful factors
If a single pre laser pulse is applied to the target, then some debris reduction is achieved, but conversion efficiency is sub-optimal
Solution Approach 1:
The pulse sequence performs preliminary conditioning of the target, optimizing its geometry and material distribution before the main laser pulse. This preliminary action ensures that the main pulse energy is converted more efficiently into desired radiation, reducing energy waste
Solution Approach 2:
The series of conditioning pulses creates a continuous useful action that progressively shapes the target while minimizing energy loss. The cumulative effect of multiple pulses at appropriate time intervals ensures efficient energy utilization compared to a single pulse approach
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 pulse sequence effectively reduces debris particle size, enhances conversion efficiency, and stabilizes the operation of the device by shaping the target and deflecting debris, leading to improved performance and longevity of the radiation source.
Implementation Method 1
at least one pulse sequence comprising at least three conditioning laser pulses is directed to the target... a main laser pulse is directed to the target... such that a radiation-emitting plasma is formed from at least a part of the target material
Implementation Method 2
A as the droplets align with the laser focus a high energy laser pulse irradiates the droplet, evaporating and ionizing a portion of the target material generating a high temperature plasma
Implementation Method 3
evaporating and ionizing a portion of the target material generating a high temperature plasma
Implementation Method 4
at least one pulse sequence comprising at least three conditioning laser pulses... time intervals... between subsequent conditioning laser pulses within the pulse sequence are 200 ns or less... effectively reduces debris particle size
Data Source
AI summary
The invention relates to a method for generating electromagnetic radiation by a laser-produced plasma, wherein a target comprising a target material is provided, at least one pulse sequence is directed to said target, wherein the pulse sequence comprises at least three conditioning laser pulses, wherein time intervals between subsequent conditioning laser pulses are 200 ns or less, and a main laser pulse is directed to said target along a first axis, such that a radiation-emitting plasma is formed from at least a part of said target material. The invention further relates to a device for generating electromagnetic radiation by means of a laser-produced plasma comprising a dispensing device and at least one laser source, wherein the device is configured such that at least one pulse sequence comprising at least three conditioning laser pulses and a main laser pulse can be generated by the at least one laser source.