Abstract Magnetic reconnection efficiently converts magnetic energy into plasma kinetic energy. With magnetic free energy stored in the current layer, previous numerical simulation studies, which focused on fixed localized regions surrounding X -lines, have demonstrated that the released magnetic energy is primarily converted into enthalpy flux and redirected Poynting flux. Electron acceleration has been widely observed in the separatrix, current layer, and exhaust. However, a quantitative analysis of how individual physical terms characterize energy transfer across distinct regions and evolutionary stages remains lacking. Using full-particle simulations of single-X-line reconnection, we dynamically partition the reconnection domain into the inflow region, separatrix region (SR), electron current layer (ECL), and exhaust region (ER) based on naturally occurring physical boundaries. Our results show that: 1. During antiparallel reconnection, the magnetic energy in the ECL remains nearly constant, where dissipation is balanced by inflow injection; in guide-field reconnection, the ECL exhibits a net magnetic energy increase. 2. Although the ECL features the highest energy conversion power density, the SR and ER together dominate the integrated energy conversion over the analyzed reconnection process. The introduction of a guide field reduces the fractional contribution of energy conversion within the ECL. 3. Compared with other sub-regions, the ECL channels a larger fraction of converted magnetic energy to electrons. The presence of a guide field elevates the global fraction of electron energy gain across the entire reconnection diffusion region. This work explicitly quantifies the contribution distribution of various conversion and transport terms to the energy budget in each sub-region, establishing a new quantitative framework for understanding energy release during magnetic reconnection.
Abstract The integration of a breeding blanket (BB) in a stellarator reactor poses a major challenge due to the intricate geometry and the reduced free space between plasma and coils and between neighbouring coils, which also makes maintenance by remote handling techniques difficult. Conversely, in comparison with tokamaks, the BB can benefit significantly from the steady-state operation of stellarators. While previous studies have pointed to the feasibility of a dual coolant lithium lead (DCLL) BB in stellarators such as HELIAS-5B, each device introduces a different set of geometrical constraints and integration requirements that must be addressed through a dedicated design approach. This work presents a sequential study on several aspects that have clear impact on the functionality and efficiency of a DCLL BB integrated into a stellarator design based on the CIEMAT-QI4X plasma configuration. The proposal aims to achieve accurate alignment between the magnetic field and the liquid metal flow to avoid electric insulation of the liquid metal circuits as much as possible. Although it has yet to be confirmed through numerical analysis or experimental testing, the specific alignment strategy proves to be highly effective in reducing pressure drop in the liquid metal circuits. Besides, the neutronic results point to an excellent performance in terms of tritium breeding provided there is an optimal use of the available space between the plasma and the coils, although some arrangements must be done to satisfy also the contemplated shielding requirements. Furthermore, the internal design of the blanket segments and the optimisation of the cooling system allows achieving a valuable performance in terms of balance of plant, while meeting the structural integrity criteria that have been studied at a very preliminary stage.
Abstract Current quantum algorithms for plasma physics require linearized systems, and quantum algorithms for nonlinear systems are highly system-specific. Second quantization, which is system-agnostic, has the exceptional capacity to render many systems suitable for quantum computation, i.e. finite-dimensional, linear, and unitary. We show how the Fourier mode-truncated Schrödinger–Poisson representation of the Vlasov–Poisson system can be second quantized into a finite-dimensional Hamiltonian system. With three- and five-mode examples, the second quantized system is shown to reproduce corresponding nonlinear dynamics in the Schrödinger–Poisson system in the simulated time intervals. Parallel integration of wide distributions of initial conditions of the Vlasov–Poisson system has the potential to be efficiently computable using the proposed second quantized model on a quantum computer.
We conduct a parametric study of the electron bunch characteristics in laser wakefield acceleration through the localized plasma density modulations. The plasma density modulation locally reduces the wake phase velocity, triggering a controlled injection of background electrons into the accelerating phase of the plasma wave. By tailoring the shape of the density bump, the injection can be confined to a narrow spatial region, thereby tuning the electron bunch properties. The Gaussian density bump provides efficient injection with moderate emittance, whereas the triangular and half-triangular profiles yield higher electron energies. The half-triangular profile yields the highest average energy and the lowest transverse emittance. The comparative analysis shows that the bump geometry directly governs the interplay between beam spread and charge yield. This all-optical, density-engineered injection method eliminates the need for high-Z dopants and provides a flexible pathway for producing high-quality, application-ready electron beams in compact plasma accelerators.
Abstract In this work, we present a real-time algorithm designed to monitor the 14.1 MeV fusion neutron production rate generated by Deuterium–Tritium (DT) fusion reactions. The study was proposed for fusion–fission hybrid reactors; however, the approach has the potential to be applied to any reversed-field pinch (RFP)-based DT machines currently under consideration within the fusion community. The algorithm, based on experience from TFTR and JET DT operations, continuously tracks the 14.1 MeV fusion neutron emission rate. If this parameter decreases below a predefined threshold, for example due to fuel dilution, the onset of MHD instabilities, or temporary actuator unavailability, the algorithm can trigger an alarm. This enables plasma recovery when actuator capabilities allow it, or ensures safe plasma termination when recovery is not feasible. Alpha-particle confinement in RFP plasmas has been investigated using the ORBIT code for different RFP magnetic field topologies, while the algorithm performance has been assessed through dedicated test cases in preparation for its real-time implementation.
