Actively Q-Switched Downhole LIBS for Higher Pulse Energy
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Solution Overview
Problem
Current downhole LIBS systems cannot generate sufficient pulse energy to excite and detect all elemental species, as their output pulse energy is limited by the geometry and pumping power, making it difficult to ensure the long-term retention of CO2 in underground geologic formations.
Innovation Solution
An actively Q-switched downhole LIBS system utilizing an optical fiber, a pump beam, and a coupler with a first lens for collimating the pump beam, along with a Pockels cell and second lens for focusing the output pulse to create high-energy plasma, allowing for remote control and increased pulse energy without significant changes to the system's geometry or input characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an all-solid state monolithic laser system is used in downhole LIBS, then the system can be deployed down hole, but the output pulse energy is limited and cannot reach the required 20 mJ level
Solution Approach 1:
The laser system is divided into separate components: a pump source, optical fiber for power delivery, and a downhole laser cavity with Q-switch. This segmentation allows the pump to be located away from the harsh downhole environment while delivering optical power through the fiber, enabling high pulse energy without increasing overall system complexity
Solution Approach 2:
An optical fiber acts as an intermediary to transmit pump power from the surface to the downhole laser cavity. This mediator enables power delivery to the remote location without requiring the entire laser system to be downhole, solving both the power limitation and deployment requirements
2Measurement precision
If the laser output pulse energy is increased to detect all elemental species, then detection capability improves, but the geometry and input characteristics would have to change by orders of magnitude
Solution Approach 1:
The system changes the temporal parameter of power delivery by using pulsed operation with Q-switching. This allows the same average power input to produce much higher peak pulse energies, enabling detection of all elemental species without changing the physical geometry of the system
Solution Approach 2:
The laser operates in pulsed mode with periodic Q-switching, accumulating energy in the gain medium and releasing it in high-energy pulses. This periodic action enables high peak power for detection while maintaining manageable average power and simple system geometry
3Power
If Q-switching is implemented to increase pulse energy, then output energy increases, but the system requires additional optical components and control mechanisms
Solution Approach 1:
The Q-switch component is extracted and integrated within the downhole laser cavity, separate from the pump source. This allows the Q-switching mechanism to be added without complicating the pump system or fiber delivery, achieving high pulse energy with minimal additional 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
Enables the detection of elemental species at higher energy levels, enhancing the monitoring of CO2 retention in geologic formations and supporting advanced spectroscopic analysis, including Raman spectroscopy, with improved plasma excitation and data return capabilities.
Implementation Method 1
A Pockels cell located within the laser can selectively cause the laser to pulse, resulting in high energy pulses
Implementation Method 2
laser induced breakdown spectroscopy (LIBS)
Implementation Method 3
an optical fiber, a pump beam transmitted through the optical fiber
Implementation Method 4
There is a second lens for focusing the output pulse such that it creates a plasma or spark
Data Source
AI summary
An actively Q-switched laser induced breakdown spectroscopy (LIBS) probe, utilizing an optical fiber, a pump beam transmitted through the optical fiber, a coupler, and a lens for collimating the pump beam. The actively Q-switched laser, coupled to a sensor which provides information to a computer that controls a high voltage pulser providing a pulse to a Pockels cell located within the laser which can selectively cause the laser to pulse, resulting in high energy pulses and a second lens for focusing the output pulse such that it creates a plasma or spark. The light from the spark is captured and directed back through an optical system to remote equipment for elemental and/or molecular analysis.