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The path of tokamak fusion and International thermonuclear experimental reactor (ITER) is maintaining high-performance plasma to produce sufficient fusion power. This effort is hindered by the transient energy burst arising from the instabilities at the boundary of plasmas. Conventional 3D magnetic perturbations used to suppress these instabilities often degrade fusion performance and increase the risk of other instabilities. This study presents an innovative 3D field optimization approach that leverages machine learning and real-time adaptability to overcome these challenges. Implemented in the DIII-D and KSTAR tokamaks, this method has consistently achieved reactor-relevant core confinement and the highest fusion performance without triggering damaging bursts. This is enabled by advances in the physics understanding of self-organized transport in the plasma edge and machine learning techniques to optimize the 3D field spectrum. The success of automated, real-time adaptive control of such complex systems paves the way for maximizing fusion efficiency in ITER and beyond while minimizing damage to device components. Damaging energy bursts in a tokamak are a major obstacle to achieving stable high-fusion performance. Here, the authors demonstrate the use of adaptive and machine-learning control to optimize the 3D magnetic field to prevent edge bursts and maximize fusion performance in two different fusion devices, DIII-D and KSTAR.

The authors have demonstrated a stable and tunable dual-wavelength Raman fibre laser, which can be used as a pump source for a hybrid type and gain controlled C- and L-band distributed Raman and lumped erbium-doped fibre amplifier. Intensity and wavelength tuning of the two lasing modes at 1480 nm and 1500 nm are achieved by tuning one and both of the fibre gratings used in the laser cavity, respectively.

A free-boundary Tokamak Equilibrium Solver (TES), developed for advanced study of tokamak equilibra, is described with two distinctive features. One is a generalized method to resolve the intrinsic axisymmetric instability, which is encountered after all in equilibrium calculation with a free-boundary condition. The other is an extension to deal with a new divertor geometry such as snowflake or X divertors. For validations, the uniqueness of a solution is confirmed by the independence on variations of computational domain, the mathematical correctness and accuracy of equilibrium profiles are checked by a direct comparison with an analytic equilibrium known as a generalized Solovev equilibrium, and the governing force balance relation is tested by examining the intrinsic axisymmetric instabilities. As a valuable application, a snowflake equilibrium that requires a second order zero of the poloidal magnetic field is discussed in the circumstance of KSTAR coil system.

By using gain nonlinearity characteristics of a semiconductor optical amplifier, an all-optical NAND gate at 10 Gbit/s is demonstrated. The all-optical NAND gate operates in single mechanism, which is cross-gain modulation. In the NAND gate (AB+A), Boolean AB is obtained by using signal A as a probe beam and signal B as a pump beam in SOA-1. Also, Boolean A is obtained by using the clock signal as a probe beam and signal A as a pump beam in SOA-2. By adding the two outputs from SOA-1 and SOA-2, Boolean A + AB (logic NAND) can be acquired. The extinction ratio is about 6.1 dB.

A novel optical layer performance monitoring method in transparent optical-label switching networks is presented. It is based on the signal quality correlation between the data payload and the label, which allows monitoring of the data payload signal quality by monitoring the label bit error rates. Experimental results indicate effective estimations of payload data bit error rates over an approximately 15 dB dynamic range of signal-to-noise ratio.

The Cretaceous Gyeongsang Basin, SE Korea,developed on a continental arc massif, is filed with 6-9 km thick,nonmarine (aluvial, fluvial, and lacustrine) deposits and subduc-tion-related volcanogenic rocks. The Kusandong Tuff is a thin (2-4 m thick) but lateraly extensive (ca. 200 km long) ignimbrite sheet,rhyodacitic in composition and rich in crystals (40-60 vol.%). Thetuf has been used as an important key bed for stratigraphic clas-sification and correlation of the basin fil. Overall sedimentary andcompositional characteristics of the tuf suggest, however, that thenorthern and southern parts of the tuff represent different ignim-brite units. The northern part of the tuff (NKT), lying above anerosional contact, consists of a massive division and an overlyingstratified division, whereas the southern part (SKT), lying con-formably above the substrate, has a basal layered division beneatha massive division. The NKT has distinctively higher crystal (51-61 vol.%) and lithic (7.0-7.8 vol.%) contents compared with theSKT, which contains 35-48 vol.% crystals and 0.2-2.5 vol.% lithicfragments. Major and trace element compositions are also differ-ent, suggesting that the NKT and the SKT originated from com-positionally different magmas. These results suggest that the use ofthe Kusandong Tuf as an event stratigraphic unit needs to bereconsidered and the formations adjacent to the Kusandong Tuffneed to be redefined, especially in the Milyang subbasin. KCI Citation Count: 12

We derive and study a simple 1D nonlinear model for Edge Localized Mode (ELM) cycles. The nonlinear dynamics of a resistive ballooning mode is modeled via a single nonlinear equation of the Ginzburg-Landau type with a radial frequency gradient due to a prescribed ExB shear layer of finite extent. The nonlinearity is due to the feedback of the mode on the profile. We identify a novel mechanism, whereby the ELM only crosses the linear stability boundary once, and subsequently stays in the nonlinear regime for the full duration of the cycles. This is made possible by the shearing and merging of filaments by the ExB flow, which forces the system to oscillate between a radially-uniform solution and a non-uniform solitary - wave like solution. The model predicts a 'phase-jump' correlated with the ELM bursts.

The experimental demonstration of dual-wavelength lasing from a cascaded Raman fiber laser, which delivers simultaneous lasing at 1480 and 1500 nm under 1313 nm pumping, is reported. The wavelength and intensity tunability of the device make it highly attractive, especially for active gain control of a Raman amplifier. The wavelength division multiplexing (WDM) coupler, which served to form a ring cavity and acted as an output simultaneously, made the laser simple and effective. The two pairs of fiber Bragg gratings that provided the resonant condition at the second Stokes order wavelength, led the laser output spectrum into a stable and tunable mode.