Reliable cross sections are essential for reactor design, transmutation performance, and nuclear data evaluation, yet significant discrepancies persist among experimental datasets, evaluated libraries, and theoretical models. This work provides a systematic assessment of the fission cross section in the fast-energy range by integrating EXFOR measurements, TALYS-2.0 calculations using five fission barrier formulations, evaluated libraries (ENDF/B-VIII.0 and TENDL-2019), and machine-learning-based predictions. A physically informed feature set including separation energies, deformation parameters, and fission barrier characteristics was used to train six regression models: CatBoost, Gradient Boosting Machine, Random Forest, Support Vector Regression, k-Nearest Neighbours, and XGBoost. GBM delivered the highest predictive accuracy and generalization, closely reproducing the experimental excitation function up to 20 MeV. TALYS results showed strong sensitivity to the barrier model. Comparative analysis demonstrates that advanced machine learning approaches can reduce high energy uncertainties and complement reaction model calculations. The findings highlight the value of data driven methodologies for improving nuclear data related to long-lived minor actinides and for supporting next generation fuel cycle and transmutation applications.
A multi-ray tracing code LHDGauss has been developed to analyze and predict the electron cyclotron resonance (ECRH) deposition profile in the LHD. The original LHDGauss had been developed so that the injected ECRH elliptical Gaussian beam is modeled by multi-ray for O or X mode, and the ray behavior and power deposition profile are calculated for a given density and temperature profile on a given fixed flux surface structure. As the LHD experiment progressed toward higher density, higher injection power, mode conversion/mixing caused by the peripheral density and strong magnetic shear became important. LHDGauss is upgraded to implement this mode conversion/mixing effect precisely. Another upgrade is automating the execution of LHDGauss using plasma parameters and configurations provided by AutoAna system to meet the large and frequent demand of ECRH power deposition profile for the confinement and transport analysis.
Tritium self-sufficiency is one of the central requirements for deuterium-tritium fusion energy. In conventional magnetic-confinement fusion systems, tritium breeding is mainly determined by the composition and geometry of the external breeding blanket, because fusion neutrons traverse the low-density plasma with negligible spectral modification. In laser-driven inertial confinement fusion, however, neutrons are born inside a highly compressed deuterium-tritium fuel assembly and may undergo significant scattering in the dense residual fuel before escaping. Here we establish a quantitative physical link between the fuel areal density, the emergent neutron spectrum, and the effective tritium-production cross section of the ⁶Li(n,α)T reaction. Using high-fidelity Monte Carlo neutron transport calculations, we show that increasing the fuel areal density from 0.3 to 5.0 g/cm² causes pronounced neutron spectral softening through elastic scattering in the compressed deuterium-tritium fuel. The average emergent neutron energy decreases from 13.74 to 8.67 MeV, while the spectrum-averaged ⁶Li(n,α)T cross section increases from 0.030 to 2.071 barn, corresponding to an approximately 69-fold enhancement. These results reveal a strong nonlinear link between microscopic fuel compression and the tritium-breeding potential. The compressed inertial-fusion target therefore acts not only as a fusion-energy source but also as an intrinsic neutron spectral shaper, which may provide a favorable spectral effect for tritium breeding and potentially benefit tritium self-sufficiency in inertial fusion energy systems.
Li4SiO4 (Lithium orthosilicate) is considered one of the most promising tritium breeder materials for next-generation fusion reactors. In reactor system, Li4SiO4 is planned to use in form of ceramic pebbles packed into the breeding blanket. The successful fabrication of these pebbles begins with material synthesis, which necessitates a comprehensive understanding of the reaction kinetics. In the present study, Li4SiO4 was synthesized using Li2CO3 and SiO2 precursor material in a 2:1 molar ratio. The synthesis of Li4SiO4 was carried out at four different temperatures of 773 K, 943 K, 1073 K, and 1173 K using a muffle furnace. The X-ray diffraction patterns confirmed the Li4SiO4 with monoclinic crystal structure at 1173 K. To further investigate the reaction mechanism, thermogravimetric studies were conducted on the mixed raw materials by five different heating rates ranging from 300 to 1173 K. The activation energies for different reaction steps were determined by using FWO, KAS, Friedman, and Vyazovkin method. The reaction model’s evaluation by Malek method indicated the reactions followed D3-diffusion controlled mechanism. Additionally, pre-exponential factors were calculated for multiple step reactions, providing deeper insight into the reaction kinetic behavior.
This paper presents an analysis of 2.45 GHz Lower Hybrid (LH) antenna design for four fundamental phasing configurations in the Alborz tokamak, focusing on optimal antenna-plasma coupling using the Advanced LOwer Hybrid Antenna (ALOHA) coupling code. Four scenarios, corresponding to these phasing configurations were investigated against a two-layer edge density profile characterized by a density step at the antenna face ( n_e0 ) and two density gradient scale lengths: one for the low-density private plasma in front of the antenna ( λ_1=2 mm ) and one for the Scrape-Off Layer (SOL— λ_2=2 cm ). Key coupling metrics—weighted directivity ( D_CD ), reflection coefficient (RC), and parallel refractive index power spectrum ( P(N_∥ ) )—were examined simultaneously across a range of edge densities, including the slow-wave cutoff value ( 7.44× 10^16 m^-3 ). According to this analysis, two scenarios were excluded. Scenario 1 was rejected due to performance degradation, with an increase in RC of up to 16% as density rose, and because of a risk of restricted Lower Hybrid Waves (LHWs) accessibility ( N_∥ >N_∥ crit ). Scenario 4 was discarded owing to poor coupling (RC= 18% at low densities) and a symmetric P(N_∥ ) that launched comparable power into both the main and back lobes, resulting in simultaneous co- and counter-Current Drive (CD) and hence unacceptably low directivity ( D_CD≅ 22% ). The final comparison between Scenario 2 ( N_∥ =2.66 ) and Scenario 3 ( N_∥ =3.54 )—both of which satisfy LHW accessibility and exhibit an asymmetric P(N_∥ ) with efficient power concentration in the main spectral lobe, which is favorable for CD—revealed a critical trade-off. Although Scenario 3 achieved a modestly lower RC range ( 5-8% vs. 4-10% ), this improvement came at the cost of a reduction in D_CD by a factor of 1.14 from ≈ 80% to ≈ 70% . Taking this trade-off into account, Scenario 2—with φ =π /2 , a waveguide width of 1 cm , and a septum thickness of 1 mm —was identified as the optimal configuration. This configuration, maintained impedance matching across a broad range of operational densities and demonstrated superior coupling performance near the critical cutoff density compared with all other configurations, specifically, it achieved a directivity of 80% and a reflectivity of 6% as the density in front of the antenna sufficiently exceeds the cut-off value and approaches 2× 10^17m^-3 .
