Liquid-Confinement Laser Shocking to Avoid Surface Breakdown
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Solution Overview
Problem
Existing laser shock systems are limited by a breakdown mechanism at the surface of the confinement medium, restricting the maximum pressure that can be generated, which is insufficient for treating strong or thick assemblies and materials.
Innovation Solution
A laser shock system design that shifts the breakdown from the surface to the volume of the confinement medium by increasing the thickness of the confinement liquid, allowing higher laser intensity and pressure to be achieved without modifying existing lasers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the thickness of the confinement liquid is increased to shift breakdown from surface to volume, then the maximum pressure generated by laser shock is improved, but the device complexity and setup requirements worsen
Solution Approach 1:
The invention transitions from a two-dimensional surface breakdown problem to a three-dimensional volume breakdown solution by increasing the confinement liquid thickness. This dimensional change allows the laser beam to deposit energy throughout the volume of the confinement medium rather than only at the surface, thereby generating higher pressures without surface breakdown limitations.
Solution Approach 2:
The invention changes the critical parameter of confinement liquid thickness from a thin layer (conventional) to a thicker layer (at least 10 cm). This parameter change fundamentally alters the laser-matter interaction regime, enabling volume breakdown and significantly increasing the maximum pressure that can be generated while avoiding surface breakdown.
2Stress or pressure
If the laser intensity is increased to generate higher pressure, then the treatment capability for strong or thick materials is improved, but surface breakdown in the confinement medium worsens
Solution Approach 1:
The invention uses a thick confinement liquid layer as an intermediary medium between the laser beam and the target. This intermediary allows the laser energy to be deposited in the volume of the liquid rather than at the surface, enabling high pressure generation without the harmful surface breakdown effect that plagues conventional thin-layer configurations.
Solution Approach 2:
The invention converts the potential harm of surface breakdown into a benefit by using volume breakdown instead. By increasing the confinement liquid thickness, the breakdown phenomenon that would normally occur at the surface is transformed into a volume-based energy deposition mechanism, which is beneficial for generating higher pressures without damaging the surface interface.
3Stress or pressure
If the beam diameter on the target surface is reduced to increase intensity, then the pressure generation is improved, but the beam focusing requirements and optical system complexity worsen
Solution Approach 1:
The invention changes the beam diameter parameter from a small focused spot (conventional) to a larger beam diameter (at least 1.5 mm) that is focused within the volume of the confinement liquid. This parameter change allows sufficient intensity to be achieved through volume energy deposition rather than surface concentration, reducing optical system complexity.
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 system significantly increases the maximum pressure generated by laser shock, achieving pressures up to 50% higher than conventional systems, while maintaining compatibility with existing equipment and avoiding surface breakdown.
Implementation Method 1
The laser creates a very high pressure PLconf plasma by laser ablation
Implementation Method 2
The confined regime makes it possible to considerably increase the plasma pressure and its application time on the target
Implementation Method 3
This process generates a very intense shock wave (pressures in the order of GPa)
Implementation Method 4
an optical COD concentration device of focal length f configured to concentrate the beam B on the surface of the Tar target
Implementation Method 5
a tank filled with said liquid having a refractive index n
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
The invention relates to a system (10) for treating a target (Tar) by laser shock under confinement in a liquid (Liq), the system comprising a pulsed laser generating a beam (B) having a pulse duration of between 1 ns and 30 ns and a wavelength, a concentrating optical device (COD) having a focal length and configured to concentrate the beam (B) on the surface (St) of the target (Tar), the laser beam (B) incident on the concentrating device having a diameter (D), a tank (TK) filled with said liquid (Liq) having a refractive index n, a desired value of the diameter (D) of the beam on a surface (St) of the target being predetermined and noted Dst, a thickness (e) of liquid (Liq) through which the beam (B) passes before reaching the surface (St) of the target (Tar) being chosen so that a laser intensity on the surface of the liquid (Liq) is less than or equal to a laser intensity on the surface of the target (Tar) divided by 2.