Compare Papers

Paper 1

SNG-Based Real-Time Plasma Control System: From Operator Calculus to Hardware Implementation

Durhan Yazir

Year
2026
Journal
Zenodo (CERN European Organization for Nuclear Research)
DOI
10.5281/zenodo.18988234
arXiv
-

Controlling a fusion plasma is like trying to balance a spinning top inside a hurricane—while the top is millions of degrees hot and the hurricane is magnetic. Instabilities can tear the plasma apart in milliseconds, ending the reaction. For decades, we've been flying blind, reacting too slowly. Now, imagine giving the tokamak a brain—a super-fast co-processor that senses what's happening and reacts in microseconds, not milliseconds. This brain doesn't just follow pre-programmed rules; it understands the plasma through four simple mathematical operators derived from Spectral Nod Theory. What are these operators? Think of them as instincts: · One senses turbulence and dampens it before it grows. · One watches the density and gently resets it if it gets too high, preventing a collapse. · One skips the Coulomb barrier—the fundamental obstacle to fusion—by leveraging collective plasma effects to boost reactivity by up to 3.4×. · One detects instabilities like ELMs and reverses them in microseconds. We've designed a complete hardware-software system to bring these instincts to life. On the hardware side, an FPGA-based co-processor (like a specialized graphics card) sits alongside the tokamak's existing control computer, processing sensor data in under microseconds—fast enough to catch instabilities before they destroy the plasma. On the software side, a "digital twin" simulates the entire tokamak, allowing us to optimize the operators offline and even predict future behavior during experiments. The system is designed to plug into existing tokamaks like China's EAST and America's DIII-D, giving them an "upgrade kit" that could dramatically improve performance. We've estimated resource requirements, validated against current technology (FPGA-based machine learning already runs at 4.4 microseconds on DIII-D), and laid out a phased deployment roadmap. This isn't just theory—it's a blueprint for building the world's first quantum-inspired plasma operating system. The operators that dance at the Planck scale may soon dance through silicon, bringing us one step closer to practical fusion energy.

Open paper

Paper 2

A Tunable Optical Frequency Reference Module Based on a Volume Holographic Bragg Grating

Janpeter Hirsch, Simon Kubitza, Max Schiemangk, Marvin Schilling, Andreas Wicht

Year
2026
Journal
IEEE Photonics Journal
DOI
10.1109/JPHOT.2026.3654409
arXiv
-

We present a robust and compact micro-integrated, frequency-tunable, optical frequency reference module developed to improve the long-term frequency stability of lasers in quantum technology and satellite laser communication applications. The module is based on a volume holographic Bragg grating (VHBG) and features a multi-level temperature stabilization concept, packaged into a sealed housing with dimensions of <inline-formula><tex-math notation="LaTeX">$96\,\times \,96\,\times \,35\,\text{mm}^{3}$</tex-math></inline-formula>. The module has a frequency tuning range of more than <inline-formula><tex-math notation="LaTeX">$\text{65}\,\text{GHz}$</tex-math></inline-formula> with a near-linear behavior. We demonstrate short-term frequency stabilities between <inline-formula><tex-math notation="LaTeX">$2 \times 10^{5}\,\text{Hz}^{2}/\text{Hz}$</tex-math></inline-formula> and <inline-formula><tex-math notation="LaTeX">$4 \times 10^{7}\,\text{Hz}^{2}/\text{Hz}$</tex-math></inline-formula> in the Fourier frequency range from <inline-formula><tex-math notation="LaTeX">$\text{20}\,\text{Hz}$</tex-math></inline-formula> to <inline-formula><tex-math notation="LaTeX">$\text{200}\,\text{kHz}$</tex-math></inline-formula>, and a minimum overlapping Allan deviation of <inline-formula><tex-math notation="LaTeX">$\sigma (\tau =1000\,s) = 1.7 \times 10^{-10}$</tex-math></inline-formula>, and <inline-formula><tex-math notation="LaTeX">$1.5 \times 10^{-9}$</tex-math></inline-formula> over 24<inline-formula><tex-math notation="LaTeX">$\,$</tex-math></inline-formula>h. The module can also be operated as a wavemeter and spectrometer, yielding residuals below <inline-formula><tex-math notation="LaTeX">$\text{0.33}\,\text{GHz}$</tex-math></inline-formula> with second-order polynomial regression calibration, and reliably measuring frequency noise PSDs of lasers whose noise exceeds that of the reference module.

Open paper