General Fusion is a BC based company with a goal of transforming the world’s energy supply by bringing zero-carbon fusion power to the grid.
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General Fusion is working toward a large-scale fusion demonstration plant (FDP) to showcase their novel Magnetized Target Fusion (MTR) technology. Achieving General Fusion’s goals requires sophisticated development and advancement in several science, engineering, and technology disciplines. In order to support these advancements, it is necessary to record vast amounts of high quality, reliable, and quickly available diagnostic data.
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General Fusion approached Motus in late 2022 to assist with development of a modular sensor data acquisition architecture that could meet their shorter term diagnostic needs and would be scalable to the full FDP.
Background
Motus embarked on an initial phase of collaboration and communication with General Fusion to better understand the application and technical challenges.
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General Fusion runs regular development tests on several plasma injector (PI) machines. Each test consists of a high current “shot” of several megaamps over a short duration injected into a plasma injector machine from a bank of supercapacitors, creating high voltage gradients and harsh electromagnetic interference (EMI)
Understanding the Need
Up to several hundred diagnostic sensors are connected to various parts of the PI machine to collect data during the test. The analog sensors are mounted on the PI machine and wire leads need to be kept short to mitigate signal noise. This results in a tradeoff where the instrumentation electronics are also very close and are subjected to extremely harsh EMI. A shielded enclosure in the plasma machine room mitigates the EMI effects, yet there are still several challenges inherent in the installation.
Defining the Problem
With various types of sensors requiring sample clocks ranging from kHz to GHz, General Fusion had employed a variety of data acquisition equipment living “side by side” within the enclosure. In order to transmit data from the enclosure in the plasma machine room to the data collection system located in a separate low EMI “screen room”, conversion of each sensor channel to an optical analog format was required. Copper wiring would be subjected to too much interference and would provide too little electrical isolation.
The several hundred analog channels resulted in a large amount of optical fibre runs, which could be unreliable and difficult to scale.
The Solution
Motus developed a modular data acquisition system architecture. The solution would allow EMI and voltage “hardening” to be designed into the hardware solution, instead of it being an afterthought. Standardized analog sensor instrumentation electronics were designed to interface with a multi-channel digitizer, based on a SOM (system on module) with a built-in processor and FPGA fabric.
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The approach facilitated a scalable system of these digitizers in the plasma machine room enclosure, with data transmitted to the screen room over a vastly reduced number of digital optical fibres. Included was a digital PLL based, sub-nanosecond accurate clock sync protocol to unlock new opportunities for analysis and sensor fusion across multiple sensors. Sample rates were configurable from 200 kHz to 2 GhHz with a variety of oversampling options and durations.
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A floating power supply solution and electrical system and grounding was architected to facilitate isolation of the diagnostic system during plasma shots, and to provide redundant electrical “means of protection” for operators of the equipment.