Radiation Damping Research Articles

Velocity growth estimate for the Vlasov–Poisson system with radiation damping

Velocity growth estimate for the Vlasov–Poisson system with radiation damping

Green upgrading of SPring-8 to produce stable, ultrabrilliant hard X-ray beams.

SPring-8-II is a major upgrade project of SPring-8 that was inaugurated in October 1997 as a third-generation synchrotron radiation light source. This upgrade project aims to achieve three goals simultaneously: achievement of excellent light source performance, refurbishment of aged systems, and significant reduction in power consumption for the entire facility. A small emittance of 50 pm rad will be achieved by (1) replacing the existing double-bend lattice structure with a five-bend achromat one, (2) lowering the stored beam energy from 8 to 6 GeV, (3) increasing the horizontal damping partition number from 1to 1.3, and (4) enhancing horizontal radiation damping by installing damping wigglers in long straight sections. The use of short-period in-vacuum undulators allows ultrabrilliant X-rays to be provided while keeping a high-energy spectral range even at the reduced electron-beam energy of 6 GeV. To reduce power consumption, the dedicated, aged injector system has been shut down and the high-performance linear accelerator of SACLA, a compact X-ray free-electron laser (XFEL) facility, is used as the injector of the ring in a time-shared manner. This allows the simultaneous operation of XFEL experiments at SACLA and full/top-up injection of the electron beam into the ring. This paper overviews the concept of the SPring-8-II project, the system design of the light source and the details of the accelerator component design.

Classicalization of Quantum Mechanics: Classical Radiation Damping Without the Runaway Solution

In this paper, we review a new treatment of classical radiation damping, which resolves a known contradiction in the Abraham–Lorentz equation that has long been a concern. This radiation damping problem has already been solved in quantum mechanics by the method introduced by Friedrichs. Based on Friedrichs’ treatment, we solved this long-standing problem by classicalizing quantum mechanics by replacing the canonical commutation relation from quantum mechanics with the Poisson bracket relation in classical mechanics.

Multimode Masers of Thermally Polarized Nuclear Spins in Solution NMR.

We present experimental single and multimode sustained ^{1}H NMR masers in solution on thermally polarized spins at room temperature and 9.4T achieved through the electronic control of radiation feedback (radiation damping). Our observations illustrate the breakdown of the usual three-dimensional Maxwell-Bloch equations for radiation feedback and a simple toy model of few coupled classical moments is used to interpret these experiments. This Letter represents a significant step to bring the spontaneous radiation damping based NMR masers in various contexts to the next stage of feedback-controlled and reproducible experiments.

Two-dimensional viscous study of coupled nonlinear fluid resonances in two narrow gaps

The wave-induced hydrodynamics of coupled nonlinear piston-mode fluid resonances within two narrow gaps between three barges are numerically investigated using a two-dimensional viscous wave flume. This study aims to explore the time-dependent nonlinear interactions between fluid oscillations in the two gaps. The coupled synchronous dynamic behaviors of fluid oscillations during the transient evolution stage are first examined in terms of amplitude and frequency modulation. It is shown that phase dynamics, including phase slipping, trapping, and locking, play significant roles in establishing the coupled synchronous dynamic evolutions of fluid oscillations in the two gaps. The quasi-steady state of the amplitude- and phase-frequency responses of fluid oscillations within the gaps, along with the reflection and transmission waves in front of and behind the three-barge system, are further analyzed. This analysis clarifies the significance of viscous damping energy dissipation and radiation damping energy transfer involved in gap resonance problems. This clarification also explains the performance of fully nonlinear potential flow solvers in predicting fluid resonances in the two narrow gaps. Finally, the nonlinear dynamic features of fluid oscillations are examined. The effects of incident wave nonlinearity, i.e., wave steepness, on resonant frequencies, response amplitudes, energy dissipation, and reflection and transmission coefficients are investigated. Harmonic analysis via Fourier transformation reveals the contributions of first-, second-, and third-order harmonics to the overall response amplitudes. The physical insights gained from this study provide a deeper understanding of the coupled nonlinear dynamics of piston-mode fluid resonances in multiple narrow gaps.

Dual-energy electron storage ring

A dual-energy electron storage ring is a novel concept initially proposed to cool hadron beams at high energies. The design consists of two closed rings operating at significantly different energies: the low-energy ring and the high-energy ring. These two rings are connected by an energy recovery linac (ERL) that provides the necessary energy difference. The ERL features superconducting radio-frequency (SRF) cavities that first accelerate the beam from the low energy EL to the high energy EH and then decelerate the beam from EH to EL in the next pass. The different SRF cavities in the ERL section can be adjusted based on the applications. In this paper, we present a possible layout of a dual-energy electron storage ring. The preliminary optics of the ring is designed to optimize chromaticity correction, dynamic aperture, momentum aperture, beam lifetime, radiation damping, and intrabeam scattering effects. The primary focus of this paper is on the stability conditions and beam dynamics studies associated with this storage ring. Published by the American Physical Society 2024

Viscous effects on the hydrodynamic performance of a two-body wave energy converter with a damping plate

In this study, the hydrodynamic forces and power absorption performance of an autonomous underwater vehicle (AUV)-based two-body wave energy converter (2BWEC) are investigated. A theoretical model is developed within the framework of linear potential flow to solve for added mass, radiation damping, and wave excitation force using the matched eigenfunction expansion method (MEEM). A computational fluid dynamics (CFD) model is employed to account for vortex-shedding effects of the floater and inner cylinder with a damping plate under various excitation conditions. Empirical formulas for supplementary added mass and drag coefficients caused by flow separation are proposed based on curve-fitting the differences between CFD results and MEEM calculations. These formulas are integrated into motion equations to enhance accuracy in evaluating the power absorption of the 2BWEC. It has been found that in the context of viscous flow, both the added mass and damping coefficients are increased, particularly for the inner cylinder with a damping plate. In addition, the viscous hydrodynamic coefficients exhibit strong dependence on the Keulegan–Carpenter number, while showing insensitivity to changes in the frequency parameter β. The supplementary (viscous) added mass provides additional inertia for the AUV with a limited mass itself, which is advantageous for the power absorption of the AUV-based 2BWEC. Conversely, the presence of viscous damping from the damping plate impedes wave energy capture.

Modeling of High-Performance Fiber Optic SPR Sensor for Colorectal Cancer Detection Designed Using Amorphous Silicon and TiO2 Layers Under Optimum Radiation Damping

Modeling of High-Performance Fiber Optic SPR Sensor for Colorectal Cancer Detection Designed Using Amorphous Silicon and TiO₂ Layers Under Optimum Radiation Damping

A novel method for solving the seismic response of non-horizontally layered half-space

In this paper, a novel method is developed to solve the free-field motion of the non-horizontally layered half-space subjected to seismic excitation in the time domain. The total wave motions are decomposed into a known and an unknown wave motion. Making use of the fact that the nodal forces at nodes in half-space resulted from the two motions will be zeros, the scattering problem resulted from the seismic excitation is transformed into a radiation problem. The radiation damping of the unbounded layered foundation in the time domain is expressed by the acceleration unit-impulse response matrix obtained using the scaling surface based Scaled Boundary Finite Element Method (SBFEM). In the numerical examples, firstly, the accuracy of the scaling surfaced based SBFEM in simulating the radiation damping is demonstrated by surface excitations in the layered half-space. Then, a time-domain analysis of the free-field motion of a horizontally layered half-space is studied to verify the accuracy and validity of the proposed method. Finally, a study of the free-field motion of non-horizontally layered half-space is investigated, and the results show that increasing the dimensions of the computational domain can significantly improve the accuracy.

Isotope effects and Alfvén eigenmode stability in JET H, D, T, DT, and He plasmas

While much about Alfvén eigenmode (AE) stability has been explored in previous and current tokamaks, open questions remain for future burning plasma experiments, especially regarding exact stability threshold conditions and related isotope effects; the latter, of course, requiring good knowledge of the plasma ion composition. In the JET tokamak, eight in-vessel antennas actively excite stable AEs, from which their frequencies, toroidal mode numbers, and net damping rates are assessed. The effective ion mass can also be inferred using measurements of the plasma density and magnetic geometry. Thousands of AE stability measurements have been collected by the Alfvén Eigenmode Active Diagnostic in hundreds of JET plasmas during the recent Hydrogen, Deuterium, Tritium, DT, and Helium-4 campaigns. In this novel AE stability database, spanning all four main ion species, damping is observed to decrease with increasing Hydrogenic mass, but increase for Helium, a trend consistent with radiative damping as the dominant damping mechanism. These data are important for confident predictions of AE stability in both non-nuclear (H/He) and nuclear (D/T) operations in future devices. In particular, if radiative damping plays a significant role in overall stability, some AEs could be more easily destabilized in D/T plasmas than their H/He reference pulses, even before considering fast ion and alpha particle drive. Active MHD spectroscopy is also employed on select HD, HT, and DT plasmas to infer the effective ion mass, thereby closing the loop on isotope analysis and demonstrating a complementary method to typical diagnosis of the isotope ratio.

Shock Response of Water-Protected Spherical Explosion Containment Vessels

Abstract Explosion containment vessels (ECVs) are important equipment used for underwater explosion experiment research. In this paper, a method is proposed to improve the blast resistance of the ECV by placing it in the water medium. The shock response caused by the underwater explosion in a spherical ECV is studied. The single-layer thin-walled spherical vessel shell submerged in an infinite domain water medium is deduced and simplified as a single-degree-of-freedom elastic vibration system with viscous damping. The underwater explosion shock wave is simplified to an exponential shock loading, and the analytical solutions of the radial shock vibration of the spherical shell are obtained using Duhamel's integrals. Compared with the numerical simulation results, the accuracy of the theoretical model is verified. The study results show that the water medium radiates out vibration energy and plays an important role in eliminating vibration through damping. It is found that the vibration damping ratio can be controlled by adjusting the vessel radius and thickness, so that the vibration of the shell can be controlled within three periods and the impact fatigue can be reduced. In addition, the radiation damping of the water medium greatly reduces the maximum radial displacement of the spherical shell, which significantly improves the blast resistance of the spherical shell.

Numerical Estimation of Hydrostatic and Hydrodynamic Forces of Spar Type Offshore Wind Turbines

Abstract The focal point revolves around Floating Offshore Wind Turbines (FOWT) due to fossil fuel leakage. Numerical simulation tools have been developed to simulate the operational dynamics of FOWT under different wave conditions.In this study,a numerical approach is proposed to investigate FOWT using ANSYS-AQWA a commercial soft wares uses potential theory that employs the boundary element method to obtain the added mass, radiation damping and diffraction in three translational degrees of freedom (surge,sway,heave).in this study considers. This paper compares two numerical approaches for studying offshore structures. The first approach was conducted using WAMIT, and in this work, a verification of the with the well known Spar offshore wind turbine OC3 will be introduced. The heave response of FOWT will be considered in regular waves. Response Amplitude Operator (RAO) is considered in Heave Motion. The simulation achieves high accuracy with minimal errors, and its processing time is significantly shorter compared to CFD simulations.

A novel hybrid framework based on modified continued-fraction for pile-soil dynamic interaction of large-scale nuclear power structures

Accurate unbounded domain radiation damping and ground motion input in the near field are important for analyzing the dynamic safety of large-scale nuclear power structures (NPSs). The scaled boundary finite element method (SBFEM) can automatically satisfy the abovementioned radiation condition. However, owing to the coupling of time and space, conventional SBFEM is not competent to the analysis of large-scale structures. In this investigation, a novel coupled method is developed to improve the computational efficiency of unbounded domain dynamic stiffness using a modified continued-fraction technique. Furthermore, a set of systematic and efficient computational procedures for soil-structure interaction (SSI) are implemented based on parallel programming using a special preprocess. The proposed method is verified using three numerical examples, and another numerical application is analyzed for large-scale NPSs with a pile-raft foundation (PRF). The results show that the innovative method has wide engineering applicability with high numerical accuracy and stability, indicating that this method can be applied to the SSI dynamic seismic analysis of large-scale NPSs.

Interplay of space charge, intrabeam scattering, and synchrotron radiation in the Compact Linear Collider damping rings

Future ultralow emittance rings for e−/e+ colliders require extremely high beam brightness and can thus be limited by collective effects. In this paper, the interplay of effects such as synchrotron radiation, intrabeam scattering (IBS), and space charge in the vicinity of excited betatron resonances is assessed. In this respect, two algorithms were developed to simulate IBS and synchrotron radiation effects and integrated in the y tracking code, to be combined with its widely used space charge module. The impact of these effects on the achievable beam parameters of the Compact Linear Collider (CLIC) damping rings was studied, showing that synchrotron radiation damping mitigates the adverse effects of IBS and space charge induced resonance crossing. The studies include also a full dynamic simulation of the CLIC damping ring cycle starting from the injection beam parameters. It is demonstrated that a careful working point choice is necessary, in order to accommodate the transition from detuning induced by lattice nonlinearities to space-charge dominated detuning and thereby avoid excessive losses and emittance growth generated in the vicinity of strong resonances. Published by the American Physical Society 2024

Analytic formulas for the D -mode Robinson instability

The passive superconducting harmonic cavity (PSHC) scheme is adopted by several existing and future synchrotron light source storage rings, as it has a relatively smaller R/Q and a relatively larger quality factor (Q), which can effectively reduce the beam-loading effect and suppress the mode-one instability. By using a minimum search algorithm to solve the mode-zero Robinson instability equation of uniformly filled rigid bunches, we have revealed that the fundamental mode of PSHC with a large loaded Q possibly triggers the D-mode Robinson instability [T. He , Mode-zero Robinson instability in the presence of passive superconducting harmonic cavities, ]. This instability is a mode-zero coupled bunch instability, with an oscillation frequency close to the PSHC detuning (D-mode). Uniquely, it is anti-damped by the radiation damping effect. In this paper, we derive analytical formulas for the frequency and growth rate of the D-mode Robinson instability by taking several appropriate approximations. These formulas provide crucial insights for analyzing and understanding the D-mode Robinson instability. Published by the American Physical Society 2024

Quake-DFN: A Software for Simulating Sequences of Induced Earthquakes in a Discrete Fault Network

ABSTRACT We present an earthquake simulator, Quake-DFN, which allows simulating sequences of earthquakes in a 3D discrete fault network governed by rate and state friction. The simulator is quasi-dynamic, with inertial effects being approximated by radiation damping and a lumped mass. The lumped mass term allows for accounting for inertial overshoot and, in addition, makes the computation more effective. Quake-DFN is compared against three publicly available simulation results: (1) the rupture of a planar fault with uniform prestress (SEAS BP5-QD), (2) the propagation of a rupture across a stepover separating two parallel planar faults (RSQSim and FaultMod), and (3) a branch fault system with a secondary fault splaying from a main fault (FaultMod). Examples of injection-induced earthquake simulations are shown for three different fault geometries: (1) a planar fault with a wide range of initial stresses, (2) a branching fault system with varying fault angles and principal stress orientations, and (3) a fault network similar to the one that was activated during the 2011 Prague, Oklahoma, earthquake sequence. The simulations produce realistic earthquake sequences. The time and magnitude of the induced earthquakes observed in these simulations depend on the difference between the initial friction and the residual friction μi−μf, the value of which quantifies the potential for runaway ruptures (ruptures that can extend beyond the zone of stress perturbation due to the injection). The discrete fault simulations show that our simulator correctly accounts for the effect of fault geometry and regional stress tensor orientation and shape. These examples show that Quake-DFN can be used to simulate earthquake sequences and, most importantly, magnitudes, possibly induced or triggered by a fluid injection near a known fault system.

Theoretical modeling of a bottom-raised oscillating surge wave energy converter structural loadings and power performances

This study presents theoretical formulations to evaluate the fundamental parameters and performance characteristics of a bottom-raised oscillating surge wave energy converter (OSWEC) device. Employing a flat plate assumption and potential flow formulation in elliptical coordinates, closed-form equations for the added mass, radiation damping, and excitation forces/torques in the relevant pitch-pitch and surge-pitch directions of motion are developed and used to calculate the system's response amplitude operator and the forces and moments acting on the foundation. The model is benchmarked against numerical simulations using WAMIT and WEC-Sim, showcasing excellent agreement. The sensitivity of plate thickness on the analytical hydrodynamic solutions is investigated over several thickness-to-width ratios ranging from 1:80 to 1:10. The results show that as the thickness of the benchmark OSWEC increases, the deviation of the analytical hydrodynamic coefficients from the numerical solutions grows from 3 % to 25 %. Differences in the excitation forces and torques, however, are contained within 12 %. While the flat plate assumption is a limitation of the proposed analytical model, the error is within a reasonable margin for use in the design space exploration phase before a higher-fidelity (and thus more computationally expensive) model is employed. A parametric study demonstrates the ability of the analytical model to quickly sweep over a domain of OSWEC dimensions, illustrating the analytical model's utility in the early phases of design.

Multiple hybrid Spp-Tamm modes in Ag grating/DBR microcavity

High confinement of surface plasmon polariton (SPP) have important applications in many aspects. However, access to high-Q resonant modes in metal cavity have many difficulties because of high Ohmic losses, large radiative losses and limited cavity designs. The Tamm mode is another surface plasmonic mode which has a high Q value but poor confinement. Here, we present a grating Tamm structure in which both nonradiative and radiative damping are suppressed, enabling excitation of high-Q and high confinement of hybrid SPP-Tamm mode. Theoretical analysis and simulations show that the proposed structure supports six resonance modes. By manipulating the geometric parameters of the metal grating, the multiple hybrid SPP-Tamm resonances could be well-defined and tuned with wavelength tuning sensitivity up to 1 nm. These results are promising for potential applications such as multiplexing, multi-frequency sensing and imaging.

Dual-Interface Solar Evaporator with Highly-Efficient Thermal Regulation via Suspended Multilayer Design.

Facing the increasing global shortage of freshwater resources, this study presents a suspended multilayer evaporator (SMLE), designed to tackle the principal issues plaguing current solar-driven interfacial evaporation technologies, specifically, substantial thermal losses and limited water production. This approach, through the implementation of a multilayer structural design, enables superior thermal regulation throughout the evaporation process. This evaporator consists of a radiation damping layer, a photothermal conversion layer, and a bottom layer that leverages radiation, wherein the bottom layer exhibits a notable infrared emissivity. The distinctive feature of the design effectively reduces radiative heat loss and facilitates dual-interface evaporation by heating the water surface through mid-infrared radiation. The refined design leads to a notable evaporation rate of 2.83kg m-2 h-1. Numerical simulations and practical performance evaluations validate the effectiveness of the multilayer evaporator in actual use scenarios. This energy-recycling and dual-interface evaporation multilayered approach propels the design of high-efficiency solar-driven interfacial evaporators forward, presenting new insights into developing effective water-energy transformation systems.

The storage ring of the Compton source of the NCPM

In this paper, the magnetic structure of the storage ring of an X-ray source based on the effect of Compton backscattering and designed for use in the electron beam energy range from 35 MeV to 120 MeV is investigated. For this storage ring, the results of calculating the dynamics of the electron beam are presented and the effects of radiation damping, quantum excitation, laser damping and intrabeam scattering are considered. The dynamic aperture and energy acceptance of this ring are discussed. The results of calculating the magnitude of the spectral brightness of X-ray radiation and its change over time are presented.