How Quickly and Accurately Can the Bubble’s Position Be Determined?
The BSF system determines the bubble’s position with millimeter-scale precision and can update that position thousands of times per second. Here’s how it achieves this without using conventional optics.
Why It’s Accurate
- Direct binary detection The system doesn’t use lenses or images like a camera. Instead, it uses hundreds of optical emitters and detectors that operate via yes/no logic: did the light pulse arrive or not? This binary simplicity reduces ambiguity and allows for ultra-precise spatial mapping.
- Occultation-based triangulation When the fuel bubble blocks a light path between an emitter and a detector—what’s called an occultation—the system detects this absence and uses it as a geometric constraint. With enough blocked lines from many angles, it can triangulate the bubble’s position to high resolution.
- Optimal sensor placement Sensor fibers are distributed along an Archimedean spiral, which ensures a uniform spread across the sensor’s spherical surface. This avoids oversampling in some areas and undersampling in others, keeping the data both dense and efficient.
Why It’s Fast
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Laser speed & time multiplexing Each laser emitter can pulse in under 3 nanoseconds, while light takes more than 10x that long to cross the sphere and reflect back. This, window of time, enables the system to send out a rapid series of non-overlapping pulses from multiple emitters.
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Pulse bursts Because of the short pulse duration and predictable light travel times, several light pulses can be sent in a rapid burst without interference. A brief delay (damping period) should follow each burst to let reflections fade, so a true signal can be distinguished from a false echo.
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Focused follow-up scans After the bubble is initially located, the system no longer needs to scan the entire sphere. It narrows its attention to just the bubble’s perimeter, where new occultations will occur if the bubble moves or changes. This drastically reduces scan volume, allowing thousands of full perimeter scans per second—enabling real-time tracking of bubble dynamics.
Final Answer with Context
- Position resolution: ~1 millimeter
- Initial scan time: ~tens of microseconds
- Real-time tracking: ~thousands of updates per second
This performance is possible because the system sidesteps slow image reconstruction and avoids optical distortion by using direct detection and geometric computation. The clever arrangement of fibers and smart time-based signaling make it both highly accurate and exceptionally fast—which is exactly what fusion diagnostics demand.