Spark Gap Ignition Using Time-Stretched Laser Pulses

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Solution Overview

Problem

Existing overvoltage protection systems using high-energy laser pulses to ignite a spark gap damage the optical waveguide due to high local intensity, necessitating the use of expensive, energy-resistant waveguides.

Innovation Solution

The system employs an optical stretching element to time-stretch laser pulses before transmission through an optical fiber, which are then temporally compressed by an optical compressor element to ignite the spark gap, reducing the maximum local energy density in the fiber and allowing the use of less expensive waveguides.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high-energy laser pulses are transmitted directly through the optical waveguide to ignite the spark gap, then the spark gap can be reliably ignited, but the optical waveguide is damaged due to high local intensity

Engineering Contradiction:
Improvespark gap ignition reliabilityVSAvoidoptical waveguide damage
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The laser pulse is stretched in time before entering the optical waveguide, reducing the peak power and energy density that would otherwise damage the waveguide. This preliminary action prepares the laser pulse in a safe state for transmission, and the compression back to high intensity occurs only at the spark gap location where it is needed for ignition.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The optical waveguide serves as an intermediary medium that transports laser energy from the laser source to the spark gap. By stretching the pulse before transmission through this intermediary, the system protects the intermediary from damage while still delivering the required energy to the target.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Strength

If expensive, energy-resistant optical waveguides are used to transmit high-energy laser pulses, then the optical waveguide can withstand the energy load, but the system cost increases significantly

Engineering Contradiction:
Improveoptical waveguide energy resistanceVSAvoidsystem cost
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The temporal parameters of the laser pulse are changed by stretching it in time before transmission through the optical waveguide. This parameter change reduces the peak power and energy density to levels that standard, inexpensive optical waveguides can handle, eliminating the need for expensive, specialized waveguides while maintaining system functionality.

Inventive Principle:
Principle #35Parameter changes

3Object-affected harmful factors

If the laser pulses are stretched in time before transmission, then the maximum local energy density in the optical fiber is reduced, but the pulse duration increases

Engineering Contradiction:
Improveoptical fiber energy densityVSAvoidlaser pulse duration
Core Design Contradiction:
Object-affected harmful factorsVSDuration of action of moving object

Solution Approach 1:

The system dynamically adjusts the temporal characteristics of the laser pulse at different stages: stretching the pulse during transmission through the optical fiber to reduce energy density, then compressing it back to the original short duration at the spark gap to ensure reliable ignition. This dynamic transformation resolves the contradiction between low energy density during transmission and short duration for effective ignition.

Inventive Principle:
Principle #15Dynamics

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 approach extends the service life of the optical waveguide and reduces costs by minimizing damage from high-energy laser pulses while ensuring reliable ignition of the spark gap.

Implementation Method 1

an optical stretching element which is used to stretch the laser pulses generated by the laser in time

Methodology Applied
Scientific EffectOptical stretching: Dispersion (of waves)

Implementation Method 2

an optical compressor element, which serves to compress the laser pulses in terms of time

Methodology Applied
Scientific EffectOptical compression: Dispersion (of waves)

Implementation Method 3

a laser for igniting the spark gap

Methodology Applied
Scientific EffectLaser-induced breakdown: Laser Ablation

Data Source

PatentEP3075041B1Overvoltage protection comprising a spark gap
Publication Date: 2018.06.27 SIEMENS AG
  • EP3075041B1 patent drawingFigure 1~2
  • EP3075041B1 patent drawingFigure 3~5

AI summary

The invention relates to an overvoltage protection comprising a spark gap (9) and a laser (210) to ignite the spark gap. The laser (210) is connected to an input (226) of an optical elongation element (218) which serves to temporally elongate the laser pulses (310) generated by the laser. The output(230) of the elongation element (218) is connected to one end of an optical transmission fiber (15'), in particular to one end of an optical waveguide (15'). A second end of the transmission fiber (15') is connected to an input (234) of an optical compression element (238) which serves to temporally compress the laser pulses (410). An output (242) of the compressor element (238) is connected to the spark gap (9).