Hollow-Core Photonic Crystal Fiber Laser Trigger for High-Voltage Gas Switches
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Solution Overview
Problem
Current high-voltage gas switches face challenges in achieving reliable triggering with fast rise times and low jitter, especially in small form-factor, low-inductance designs capable of operating at high pressures and voltages, due to limitations in plasma formation and energy delivery via conventional optical fibers.
Innovation Solution
The use of hollow-core photonic-crystal-fiber (HC PCF) to deliver high-power laser pulses directly to the anode-cathode gap of a high-voltage gas switch, enabling efficient plasma generation with improved beam quality and peak irradiance, thereby facilitating command fire switch closure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional optical fibers are used to deliver laser triggers, then the system structure is simpler, but the peak irradiance and beam quality are insufficient for reliable plasma formation
Solution Approach 1:
The patent changes the physical and optical parameters of the fiber by using photonic crystal fiber structure with hollow core, which fundamentally alters the light propagation characteristics compared to conventional fibers, enabling high peak irradiance delivery while maintaining beam quality
Solution Approach 2:
The patent employs a composite structure combining photonic crystal fiber with hollow core design, integrating the advantages of photonic bandgap materials and hollow waveguide structures to achieve superior optical performance for laser trigger delivery
2Speed
If the AK gap distance is reduced to achieve faster rise times, then the switch speed improves, but the voltage breakdown and plasma formation become more difficult
Solution Approach 1:
The patent applies preliminary action by using the laser trigger to pre-ionize the gas in the AK gap before the main voltage breakdown occurs, creating a conductive plasma channel that facilitates reliable and fast switch closure even at reduced gap distances
Solution Approach 2:
The patent applies local quality by concentrating the laser energy into a focused beam that creates a localized plasma region with high electron density at the electrode surface, enabling reliable breakdown initiation in the specific critical region where it is most needed
3Reliability
If high laser energy is used to ensure plasma formation, then the triggering reliability improves, but the energy consumption and potential damage increase
Solution Approach 1:
The patent uses local quality by focusing laser energy into a concentrated beam that creates a high-intensity plasma channel only in the specific region of the AK gap where breakdown is needed, rather than distributing energy throughout the entire gap, thus achieving reliable triggering with minimal energy consumption
Solution Approach 2:
The patent replaces the conventional mechanical or high-energy electrical triggering methods with optical field-based laser triggering, using the photonic crystal fiber to deliver precisely controlled laser pulses that initiate plasma formation with lower overall energy input
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 solution allows for reliable operation at pressures up to 2200 psi, voltages over 200 kV, and jitter as low as 3 ns, with the ability to generate a plasma using as little as 500 μJ of laser energy, achieving peak irradiances significantly higher than conventional systems, ensuring efficient and precise switching.
Implementation Method 1
hollow-core photonic-crystal-fiber (HC PCF) to deliver high-power laser pulses
Implementation Method 2
high power Nd:YAG pulsed laser (FHWHM ̃5 ns, 1064 nm wavelength, M2 ̃1.25) that is coupled into a HC PCF
Implementation Method 3
peak irradiance of the laser trigger can be greater than 5.1×1011 W/cm2 for a laser having a wavelength of 1064 nm
Data Source
AI summary
A photonic-crystal-fiber-delivered laser-triggered high-voltage gas switch can deliver a peak irradiance of greater than 5.1×1011 W/cm2 to the AK gap for a laser having a wavelength of 1064 nm. The switch is capable of operating at pressures up to 2200 psi; voltages across the gap of greater than 200 kV; operation at less than 70% self-break voltage; shot-to-shot jitter of less than 3 ns; AK gap distances of 3 mm or smaller; and triggering via a fiber-delivered laser pulse energy of as low as 500 μJ.