27: Chapter 27 Ignition of the Miniaturized Fusion Device "Candle Dragon"
The shockwave of "bedrock-1" vibrated in both the real world and the theoretical cloud, but within the "Sky Vault" plateau base, time still flowed according to its unique rhythm, related only to the speed of thought. After being greatly encouraged by the "bedrock" results, the "Deep Blue" virtual theory group entered a more focused and aggressive stage of theoretical breakthrough.
The high-throughput screening algorithm adjusted by "Weaver" began to scan the database of material combinations that might form strongly coupled interfaces with unprecedented precision and breadth. The goal was no longer just to find "possible" superconducting materials, but to look for "material pairs" that could theoretically produce stronger coupling effects based on the interface enhancement mechanism clues (strain, charge transfer, specific phonon coupling) provided by "bedrock-1". Some systems previously ignored due to being too complex or unstable, such as combinations of certain layered magnetic materials and strongly polar oxides, or heterojunctions of 2D transition metal sulfides and special dielectric materials, were included in the key inspection scope.
"Tide" and "Stardust" joined forces, attempting to deepen Lin Shen's initially extremely simplified "interface-driven" model into a more self-consistent effective field theory model containing more microscopic degrees of freedom. They introduced dynamic electron-boson coupling operators, trying to describe how two different quantum orders at the interface (such as antiferromagnetic fluctuations and optical phonons) could give birth to a brand new, higher energy scale "synthetic boson" mode through competition and collaboration. The mathematical derivation for this part was exceptionally difficult, progressing slowly but steadily.
The work of Topologist ("Topologist") provided what was perhaps the most direct and surprising periodic result. Based on the expanded theoretical model and using the powerful computing power of the "heart of deep blue," he calculated topological invariants and non-trivial Berry phases for a series of candidate heterojunction interfaces initially screened by "Weaver."
During a routine calculation, a set of topological property calculation results regarding a "tensile strain heterojunction formed by monolayer black phosphorus (BP) and a calcium fluoride (CaF2) substrate" caught Topologist's special attention. The calculations showed that within a specific strain range, the topological Chern number of the electronic states of this interface, originally thought to be mundane, underwent a non-zero jump, accompanied by the appearance of extremely flat topological flat band characteristics near the Fermi surface.
topological flat bands! This was exactly one of the ideal carriers Topologist had previously predicted theoretically that could greatly enhance electron correlation and thus increase the superconducting temperature! Although the calculation did not directly predict superconductivity, this mutation in topological properties strongly suggested that unusual electronic interactions might exist at the interface.
He sent this discovery encrypted to Lin Shen and other members of the "Deep Blue" group, along with a detailed band structure and topological analysis.
"Topologist's discovery is very valuable!" Lin Shen responded immediately. "A flat energy band means the effective mass of electrons is extremely large, kinetic energy is almost frozen, and electron-electron correlation effects will dominate. This could be an excellent breeding ground for inducing unconventional superconductivity. 'Weaver,' please immediately list the BP/CaF2 system, and other interface combinations that might produce similar topological flat bands, as top priority, and perform comprehensive calculations for electron-phonon coupling strength and possible superconducting instabilities!"
Just as the "Deep Blue" group was laboriously carving out a new path through the thickets of theory, several other fronts that Lin Shen had been following in parallel also reported milestone progress one after another.
First was an encrypted briefing from the photonics group of the "Chasing Light" project, jointly signed by He Yun and Chen Fan. After several rounds of tape-out optimization, their silicon-based on-chip tunable laser designed based on a new type of Photonic Crystal resonant cavity achieved room-temperature continuous-wave lasing in the laboratory for the first time! Although key parameters such as output power and linewidth were still some distance from commercialization, its high compatibility with silicon-based CMOS processes and the feasibility of wavelength fine-tuning through electrical tuning had been fully verified. This meant that the most critical and difficult "on-chip light source" bottleneck for photonic chips had been substantially broken through by a major step! This marked a crucial step toward achieving full silicon-based optoelectronic integration. At the end of the briefing, He Yun also cautiously mentioned that while testing the coupling efficiency between the new laser and silicon waveguides, they observed some additional loss phenomena not completely consistent with the theoretical model, possibly caused by interface photon-phonon coupling, which was being analyzed in depth—this again faintly echoed the interface physics that "Deep Blue" was concerned with.
Next was an emergency communication from Shen Hong of the "Xuance Group." The third batch of bismuth telluride (Bi2Te3)-niobium nitride (NbN) heterojunction samples, optimized by Professor Professor Wu Qingquan's team, finally reached the performance window predicted by the theoretical model! The superconducting transition temperature (Tc) stabilized at 16.5K, very close to the 17K target. More importantly, Shen Hong used the base's small low-temperature high-magnetic-field platform (maximum magnetic field 9T) to conduct preliminary electrical transport measurements on this batch of samples. At ultra-low temperatures (0.3K) and moderate magnetic fields, they observed extremely faint but repeatable signs of quantized conductance plateaus. Although the signal was still weak and background noise was high, this was very likely a sign that topologically protected edge states were beginning to emerge! Shen Hong and Topologist (balancing both sides) were stepping up data analysis and actively preparing for the joint measurement time four months away at the Hefei High Magnetic Field Laboratory with higher fields (expected to reach 30T) and lower temperatures (mK level). The physical verification of Topological Quantum Computing finally saw the first glimmer of real light penetrating the thick theoretical clouds!
Amidst this succession of good news, a briefing from Director Zhao of the Energy Security Committee, marked as "Longyuan Top Secret · Top Priority," was delivered to Lin Shen's independent terminal at the "Sky Vault" base.
The content of the briefing made even Lin Shen, who had experienced many shocks, feel his breath hitch.
The briefing first briefly reviewed the background and urgency of exploring miniaturized paths for controlled nuclear fusion, especially the unprecedentedly urgent demand for alternative paths and disruptive technologies after the blockade of key raw materials for high-temperature superconductivity.
Then, the briefing disclosed a top-secret project codenamed "Zhulong." The project was launched several years ago with the goal of verifying a miniaturized fusion experimental device based on the advanced compact Spheromak concept and partial high-temperature superconducting magnet technology.
The "Zhulong" device's design scale is much smaller than ITER or EAST, with a plasma chamber volume only equivalent to a large truck container. It uses an innovative coaxial plasma gun injection and magnetized target formation technology to start and maintain the Spheromak plasma, and utilizes a miniaturized magnet system wound with domestically developed second-generation high-temperature superconducting (REBCO) tapes based on partial replacement raw materials to provide partial confinement and stabilizing magnetic fields.
Over the past three years, the engineering team has overcome a series of extreme technical challenges such as plasma startup instability, complex magnetic field coupling control, and quench protection of high-temperature superconducting magnets during transient processes. And just seventy-two hours ago, in an extremely secret underground test site in the west, the "Zhulong" device conducted its first integrated ignition experiment at its design power!
The briefing included a summary of key experimental data that had undergone strict de-sensitization and some blurred internal monitoring images (showing only the control room and some non-core equipment).
The data showed:
Successful plasma formation and capture: The coaxial gun successfully injected and magnetized the target material, forming an initial Spheromak configuration plasma, with a continuous confinement time reaching 105 milliseconds! Although this is far shorter than the hundred-second range of a Tokamak, for such a small Spheromak device and its first integrated ignition, it is already a huge success.
Confirmation of fusion neutron production: Neutron detectors arranged around the device recorded a clear 14.1 MeV characteristic neutron signal far above the background noise! This is ironclad evidence of the deuterium-tritium (D-T) fusion reaction occurring! Although the neutron yield was not high and the fusion gain Q value was much less than 1 (energy consumed far greater than energy produced), it proved that the "Zhulong" device indeed achieved controlled fusion ignition on a microscopic scale!
Stable performance of high-temperature superconducting magnets: During this brief discharge process, the HTS magnet system prepared using alternative materials worked normally, withstanding the electromagnetic stress brought by plasma current and magnetic field changes without quenching.
Successful ignition of "Zhulong"!
Although it is still a hundred thousand miles away from "generating energy," and although it is only a "miniature spark" for principle verification, its symbolic significance and scientific value are immeasurable!
It proved that achieving controlled fusion on a miniaturized and compact path is not a fantasy. It verified the engineering feasibility of the Spheromak alternative confinement concept, especially after adopting some advanced high-temperature superconducting technologies, its potential is worth digging deep into.
Moreover, at the darkest moment when the country's key high-temperature superconducting materials were being "strangled," it used some alternative materials and some independent technology to ignite a stubborn "artificial sun" spark belonging to the Chinese people! This is not just a technical breakthrough, but a manifestation of strategic will and engineering wisdom!
The briefing finally pointed out that the success of "Zhulong" greatly boosted confidence in the field of fusion research and provided a precious, deeply iterable technical platform for the country's long-term layout of compact fusion energy. Director Zhao requested Lin Shen to immediately organize forces to conduct an in-depth analysis of the experimental data of the "Zhulong" device (more de-sensitized data will be provided later) while continuing the theoretical exploration of the "Deep Blue" project, and from its technical path, combined with the cutting-edge theoretical insights that "Deep Blue" might obtain, evaluate potential technical breakthroughs and possible limit challenges for its future performance improvement (such as extending confinement time, increasing plasma parameters, and achieving higher fusion gain).
This meant that Lin Shen's theoretical exploration finally had a real physical system to interface with and potentially influence! "Zhulong" was no longer just a concept in literature, but a real existence that was breathing and trying to burn.
Putting down the briefing, Lin Shen stood for a long time in his quiet suite at the "Sky Vault" base. The simulated exterior scene on the screen showed the plateau at sunset, with huge, burning clouds filling the sky, dyeing the distant snow peaks golden-red.
The "light" of the photonic chip had been lit; the "state" of the topological quantum was showing its first signs; and the "fire" of fusion energy had also stubbornly ignited the first spark in this most difficult moment.
Three fronts, three dimensions, were all trudging steadily toward the bright direction.
His gaze fell back to the workbench again, where there were the latest topological flat band calculation results from the "Deep Blue" group, the shocking data from the "Zhulong" ignition, and He Yun's records of doubts about interface photon-phonon coupling...
In the dark, these clues and information from different fields and scales seemed to be played with by an invisible hand, beginning to reveal some vague but definitely existing network of connections.
Interface... coupling... topology... flat band... plasma confinement... energy scale...
The outline of a grander and crazier concept loomed in his mind, which was being bombarded by multiple streams of information. But that outline was too vague and too advanced; he needed more data, deeper thinking, and... perhaps guidance from a deeper level of the technology tree.
He sat back at the workbench, categorizing, labeling, and inputting the "Zhulong" briefing, the latest progress of "Deep Blue," and key information from other projects into a highly private auxiliary database he had built for himself for cross-domain association and theoretical deduction.
Then, he connected to the top-secret communication line with Director Zhao and Academician Qin.
"Director Zhao, Academician Qin, the ignition of 'Zhulong' is of extraordinary significance! I have received the briefing and immediately started organizing the analysis." Lin Shen's voice was steady with a hint of irrepressible excitement, "The 'Deep Blue' project also has new discoveries involving mechanisms such as interface topological flat bands that could greatly enhance electron correlation. I request that, under the premise of top secrecy, a directional and limited information exchange channel be established between the 'Deep Blue' theory group and the 'Zhulong' engineering team. We might be able to provide some unconventional ideas for 'Zhulong's' future plasma heating, confinement optimization, and even fusion product energy extraction from the theoretical perspective of microscopic electronic state regulation. At the same time, the real experimental data of 'Zhulong' will also be a precious 'touchstone' for testing and correcting our frontier theoretical models."
There was a moment of silence on the other end of the communication, obviously evaluating this bold proposal that spanned theoretical exploration and large-scale engineering practice.
"Agreed." Director Zhao's voice finally came through, decisive. "Theory guides practice, and practice feeds back into theory. 'Zhulong' needs new ideas, and 'Deep Blue' needs real data. We will arrange the most reliable contacts and information filtering mechanisms. Lin Shen, go ahead and do it, but remember, safety and secrecy are above all else."
"Understood!"
The communication ended. Night had completely fallen on the plateau, and the simulated exterior scene switched to a real, brilliant starry sky.
Lin Shen felt as if he were standing at an unprecedented crossroads. Ahead was an unknown territory where microscopic particles and macroscopic stars intertwined; in his hand were road signs from different dimensions of the technology tree gradually lighting up; behind him were the earnest expectations and heavy entrustments of the country and the nation.
"Zhulong" had ignited, illuminating a corner of the darkness.
And their journey had perhaps only just begun, sailing toward that place where energy and matter, information and existence transform into each other, where the true abyss and dawn coexist.