Plasma Response Research Articles

An extended Vlasov–Fokker–Planck approach for kinetic simulations of laser plasmas

Vlasov–Fokker–Planck simulation codes occupy an important niche in modeling laser-produced plasmas, since they are well suited to studying the effect of collisions on electron kinetic phenomena, especially energy transport. One of the most important elements of energy transport is the absorption of laser light by the plasma; however, simulating this in detail requires resolving oscillations of the laser light, whose characteristic timescale is orders of magnitude shorter than the simulation time needed to study transport physics. For this reason, most Vlasov–Fokker–Planck codes used to study electron transport in laser plasmas rely on simplified models of the laser–plasma coupling. Their underlying assumptions nominally preclude their use for modeling laser light having short-scale structure in space or time, such as broadband lasers. In this work, we derive a more general computational framework suitable for arbitrarily structured laser fields. Our approach is based on an extended set of Vlasov–Fokker–Planck equations that separately solve for the low- and high-frequency plasma response. We implement these extended Vlasov–Fokker–Planck equations in the spherical harmonic code K2 and demonstrate the performance of the method on several laser absorption test problems, with particular attention to the judicious selection of time steps, time integrators, and spherical harmonic truncation, according to the intensity and spectrum of the laser light under consideration. Comparison with the widely used Langdon absorption operator shows the Langdon operator performs remarkably well for predicting laser heating in the simple cases considered here, even in situations that would seem to violate its underlying assumptions.

Response of Meteor Plasma Trails Observed by Meteor Radar to Geomagnetic Activity

AbstractFrom meteor radar observations typically measuring neutral winds and temperatures in the upper atmosphere, we showed that under‐dense meteor plasma trails respond to geomagnetic activity. Depending on the geomagnetic activity conditions, the parameters of the under‐dense trail echoes show substantial anomalies, and their responses are immediate. As geomagnetic activity increases, the decay time decreases up to about 10% at Kp = 8, while both the returned signal power and radial velocity error increase. In addition, the types of diffuse evolution vary with geomagnetic activity, resulting in strong geomagnetic activity that immediately affects the trail. The evolution of the trail is affected not only by the ambient mesospheric neutral atmospheric properties but also by electromagnetic effects, such as strong electric fields inside meteor trails. Furthermore, our findings suggest that the geomagnetic effect should be considered when estimating atmospheric parameters from MR during a geomagnetically active period.

Mitigation of the Onset of Hosing in the Linear Regime through Plasma Frequency Detuning.

The hosing instability poses a feasibility risk for plasma-based accelerator concepts. We show that the growth rate for beam hosing in the linear regime (which is relevant for concepts that use a long driver) is a function of the centroid perturbation wavelength. We demonstrate how this property can be used to damp centroid oscillations by detuning the plasma response sufficiently early in the development of the instability. We also develop a new theoretical model for the early evolution of hosing. These findings have implications for the general control of an instability's growth rate.

Liraglutide changes postprandial responses of gut hormones involved in the regulation of gallbladder motility.

Liraglutide treatment is associated with gallbladder-related disorders and has been shown to delay postprandial gallbladder refilling. The gut hormones cholecystokinin (CCK), fibroblast growth factor 19 (FGF19) and glucagon-like peptide 2 (GLP-2), are known to regulate gallbladder motility and may be implicated in gallbladder-related disorders associated with liraglutide treatment. In a double-blind, 12-week trial, 52 participants [50% male, age 47.6 ± 10.0 years, body mass index 32.6 ± 3.4kg/m2 (mean ± standard deviation)] with obesity were randomized 1:1 to once-daily subcutaneous liraglutide (escalated from 0.6mg to 3.0mg once-daily) or placebo. During liquid meal tests performed at baseline, after the first dose and following 12 weeks of treatment, we evaluated postprandial gallbladder dynamics and plasma responses of CCK, FGF19 and GLP-2. Liraglutide reduced postprandial FGF19 after the first dose [area under the curve (AUC)0-240 min 24.8 vs. 48.0min× ng/ml, treatment ratio (TR) (95% confidence interval) 0.52 (0.39; 0.69)] and following 12 weeks of treatment [AUC0-240 min 33.7 vs. 48.5ng/ml × min, TR 0.69 (0.52; 0.93)]. Liraglutide also reduced postprandial GLP-2 responses (AUC0-240 min 3650 vs. 4894 min× pmol/L, TR 0.75 (0.62; 0.90)] following the first dose as well as after 12 weeks [AUC0-240 min 3760 vs. 4882 min× pmol/L, TR 0.77 (0.60; 0.99)]. Liraglutide increased postprandial responses of CCK after the first dose [AUC0-240 min 762 vs. 670 min× pmol/L; TR 1.14 (0.97; 1.33)] and following 12 weeks of treatment [AUC0-240 min 873 vs. 628 min× pmol/L; TR 1.39 (1.12; 1.73)]. Compared with placebo, treatment with liraglutide decreased postprandial FGF19 and GLP-2 concentrations and increased postprandial CCK concentrations, which may explain the delayed postprandial gallbladder refilling observed in individuals with obesity treated with liraglutide.

Biomarkers of Oxidative Stress and Persistent Organic Pollutants in Plasma and Eggs of Chelonia mydas Nesting in the Southern Gulf of Mexico

The major nesting sites for the endangered green turtle (Chelonia mydas) are in Campeche, Mexico: Carmen, Isla Aguada, and Sabancuy. Although they are in a natural reserve, these nesting sites are threatened by agricultural activities and oil extraction. This study aimed to determine the presence and concentration of organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs) in plasma and eggs and to assess the antioxidant response in plasma of nesting C. mydas from the southern Gulf of Mexico. Using censored statistics allowed us to do a realistic calculation incorporating the presence of non-detects in the analysis. A few contaminants (α+β+γ-HCH, trans-chlordane, 4,4′-DDE, 4,4′-DDT, methoxychlor, naphthalene, acenaphthylene, 2-Bromo naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, and dibenz[a,h]anthracene) were detected in plasma and their corresponding eggs, but correlations were not-significant. Spatial differences in concentrations of persistent organic pollutants (POPs) among nesting sites may reflect differences in foraging areas. Approximately 30% of the POPs in plasma and 60% of the POPs in eggs correlated with the biomarkers of oxidative stress. Detection of POPs in C. mydas indicated that plasma and eggs are suitable matrices to assess POPs concentrations.

Plasma response impact on RMP divertor footprint modeling for KSTAR

Plasma response impact on RMP divertor footprint modeling for KSTAR

On charged photons in unmagnetized dusty plasma instabilities

Motivated by the expanding interest in complex plasmas, we discuss the equivalent photon charge in dusty electron-ion plasmas. Particularly, we investigate the dusty plasma response in terms of the electron density perturbation driven by electromagnetic waves. The resulting polarization of this plasma medium caused by the photon ponderomotive force of the electromagnetic radiation pressure gives rise to an effective photon electric charge. We determine the acquired photon charge in terms of the involved characteristic parameters. More precisely, here we derive an explicit expression of the photon charge which is found to depend strongly on the free electron density and the photon frequency. Such a photonic charge is relevant for dealing with the photon–plasma couplings in most plasma mediums, namely of the early Universe.

Cell-Free Urine and Plasma DNA Mutational Analysis Predicts Neoadjuvant Chemotherapy Response and Outcome in Patients with Muscle-Invasive Bladder Cancer.

To investigate the use of plasma and urine DNA mutation analysis for predicting neoadjuvant chemotherapy (NAC) response and oncological outcome in patients with muscle-invasive bladder cancer. Whole-exome sequencing of tumor and germline DNA was performed for 92 patients treated with NAC followed by radical cystectomy (RC). A custom NGS-panel capturing approximately 50 mutations per patient was designed and used to track mutated tumor DNA in plasma and urine. A total of 447 plasma samples, 281 urine supernatants, and 123 urine pellets collected before, during, and after treatment were analyzed. Patients were enrolled from 2013 to 2019, with a median follow-up time of 41.3 months after RC. We identified tumor DNA before NAC in 89% of urine supernatants, 85% of urine pellets, and 43% of plasma samples. Tumor DNA levels were higher in urine supernatants and urine pellets compared with plasma samples (P < 0.001). In plasma, detection of circulating tumor DNA (ctDNA) before NAC was associated with a lower NAC response rate (P < 0.001). Detection of tumor DNA after NAC was associated with lower response rates in plasma, urine supernatant, and urine pellet (P < 0.001, P = 0.03, P = 0.002). Tumor DNA dynamics during NAC was predictive of NAC response and outcome in urine supernatant and plasma (P = 0.006 and P = 0.002). A combined measure from plasma and urine supernatant tumor DNA dynamics stratified patients by outcome (P = 0.003). Analysis of tumor DNA in plasma and urine samples both separately and combined has a potential to predict treatment response and outcome.

Drift kinetic effects on plasma response to resonant magnetic perturbation for EU DEMO design

A systematic investigation of the plasma response to an externally applied resonant magnetic perturbation (RMP) field, for the purpose of controlling edge localized modes, is carried out for an EU DEMO reference plasma. Particular emphasis is placed on the role of kinetic effects associated with both thermal particles and fusion-born alphas. The single fluid, resistive model predicts a large peak amplification of the n= 1 (n is the toroidal mode number) plasma response to the target equilibrium, which is found to be close to the Troyon no-wall limit. A more advanced response model, including kinetic resonances between the RMP perturbation and drift motions of thermal and energetic particles, on the other hand, finds a strong suppression of the n= 1 field amplification. A major role is played by the precessional drift resonance of fusion-born alphas. A strong parallel sound wave damping model is found to well reproduce the full kinetic response results for the DEMO plasma, in terms of both the resonant field response amplitude and the plasma displacement. Finally, both fluid and kinetic models produce similar responses for the n = 2 and 3 RMP fields for the considered DEMO plasma, whilst kinetic effects again become important for the n = 4 RMP due to proximity of the reference plasma to the no-wall limit for the n = 4 ideal kink instability.

Simulation of ion cyclotron resonance heating by using particle-in-cell method in MPS-LD linear plasma device

The auxiliary heating of electrons and ions in linear plasma devices (LPDs) is necessary to achieve the boundary plasma relevant environment of tokamaks, to investigate the boundary physics and plasma—material interactions. In this work, the simulation of ion cyclotron resonance heating (ICRH) in the LPD multiple plasma simulation linear device (MPS-LD) is carried out by using a 3D particle-in-cell method, and the wave—ion interaction mechanism based on a ‘beach-heating’ technique in the ion heating region is investigated. A left-handed, circularly polarized wave along the magnetic field lines is used to represent the electromagnetic wave in the model, after the analysis of the cold plasma dispersion relation. The mechanism of ion heating by collisionless damping absorption is demonstrated and explained by using the plasma current as the plasma response. The dependencies of the heating efficiency on the plasma density, magnetic field strength and magnetic field configuration are studied. The correlation between plasma density and magnetic field strength, which satisfies the heating efficiency, is found and it is in perfect agreement with the theoretical derivation. Finally, by using the designed parameters of MPS-LD provided by SOLPS-ITER, the prediction of ICRH is performed. The simulation result shows that the ion temperature can be heated higher than 40 eV and it satisfies the requirement for scrape-off layer/divertor simulation experimentally in MPS-LD.

Impact of β n and spectrum of n = 1 applied fields on fast ion losses in DIII-D

The effect of n = 1 magnetic perturbations (MPs) on prompt fast ion losses in DIII-D has been investigated using the light ion beam probe technique. The effect of normalized beta, β n , and the plasma response to the MPs is studied for several MP spectra. Magnetics data show a strong dependence of plasma response to β n that depends on the phase difference in perturbation coils, . For most phases, the response increases with β n , however, the response is suppressed for phases between 180∘ and 240∘. Experimental data from scintillator based fast ion loss detectors shows that relative fluctuation of lost ions (20%–30% of the steady signal) does not diminish across the L- to H-mode transition for , despite the 34% decrease in radial response field and 50% decrease in poloidal response field. Simulations of the DIII-D discharges using M3D-C1 and ASCOT5 find that prompt losses from neutral beam injection in each investigated case hit the first wall at several concentrated locations: the vessel floor, midplane diagnostic ports, vessel ceiling, and inner wall. Simulated losses from co-injection neutral beams are born outside the last closed flux surface, corresponding to radial orbit displacements of 3–6 cm due to the MPs.

Longitudinal monitoring of mRNA-vaccine-induced immunity against SARS-CoV-2.

Worldwide vaccination campaigns significantly reduced mortality caused by SARS-CoV-2 infection and diminished the devastating effects of the pandemic. The first approved vaccines are based on novel mRNA technology and elicit potent immune responses offering high levels of protection from severe disease. Here we longitudinally assessed adaptive immune responses during a 12-month follow-up period after the initial immunization with 2 doses of mRNA vaccines and after the booster dose in blood and saliva. Our findings demonstrate a rapid waning of the anti-spike IgG titers between months 3 and 6 after the initial vaccination (1.7- and 2.5-fold decrease in plasma and saliva, respectively; P<0.0001). Conversely, the frequency of spike-specific memory B cells increased during this period (2.4-fold increase; P<0.0001) while the frequency of spike-specific CD4+ and CD8+ T cells remained stable for all assessed functions: cytotoxicity, IFNγ, IL-2, and TNFα expression. Booster vaccination significantly improved the antibody response in plasma and saliva, with the most profound changes observed in the neutralization capacity against the currently circulating omicron variant (25.6-fold increase; P<0.0001). The positive effect of booster vaccination was also evident for spike-specific IgG+ memory B cell (2.4-fold increase; P<0.0001) and cytotoxic CD4+ and CD8+ T cell responses (1.7- and 1.9-fold increase respectively; P<0.05). Collectively, our findings offer a detailed insight into the kinetics of adaptive immune response following SARS-CoV-2 vaccination and underline the beneficial effects of a booster vaccination.

Effect of Intraperitoneal 224Radium-Labelled Microparticles on Compartmentalized Inflammation After Cytoreductive Surgery and Hypertherm Intraperitoneal Chemotherapy.

Despite extensive treatment with surgery and chemotherapy many patients with peritoneal metastases from colorectal cancer experience intraperitoneal disease relapse. The α-emitting 224radium-labelled microparticle radionuclide therapeutic Radspherin® is being explored as a novel treatment option for these patients. Radspherin® is specially designed to give local radiation to the surface of the peritoneal cavity and potentially kill remaining attached micrometastases as well as free-floating cancer cells, thus preventing future relapse. The effect of Radspherin® on the immune system is not known. Systemic and local inflammatory responses were analyzed in plasma, intraperitoneal fluid and urine collected prospectively as part of a phase 1 dose-escalation study of intraperitoneal instillation of the α-emitting therapeutic radiopharmaceutical Radspherin®, at baseline and the first 7 postoperative days from nine patients undergoing cytoreductive surgery and hyperthermic intraperitoneal chemotherapy. All patients additionally received intraperitoneal instillation of Radspherin® on postoperative day 2. Complement activation products C3bc and the terminal complement complex were analyzed using enzyme-linked immunosorbent assay. Cytokines (n = 27), including interleukins, chemokines, interferons and growth factors, were analyzed using multiplex technique. The time course and magnitude of the postoperative cytokine response after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy displayed a modest systemic response in plasma, in contrast to a substantial local intraperitoneal response. After administration of Radspherin®, a significant increase (P < 0.05) in TNF and MIP-1β was observed in both plasma and peritoneal fluid, whereas IL-9 increased only in plasma and IFNγ and IL1-RA only in peritoneal fluid. Only minor changes were seen for the majority of the inflammatory markers after Radspherin® administration. Our study showed a predominately local rather than systemic inflammatory response to cytoreductive surgery and hyperthermic intraperitoneal chemotherapy. Radspherin® had overall modest impact on the inflammation.

Effect of aspect ratio on plasma response to resonant magnetic perturbations in tokamak devices

A systematic numerical study is carried out, computing and comparing the plasma response to the resonant magnetic perturbation (RMP) field, applied for controlling edge localized modes (ELMs), in a series of tokamak plasmas with varying aspect ratio and utilizing the MARS-F code. The aspect ratio is scanned either by varying the plasma major radius at a fixed minor radius or by varying the latter while fixing the former. Both approaches yield similar results when compared in terms of quantities with proper normalizations. In general, a non-monotonic dependence of the resonant response field (normalized by the vacuum counterpart) near the plasma edge is found with varying aspect ratio, indicating that a given ELM control coil current configuration strongly favors plasmas with a certain aspect ratio. This optimal aspect ratio, on the other hand, depends on the toroidal as well as poloidal (i.e., coil phasing) spectra of the applied RMP field. The equilibrium (edge) safety factor, the plasma shape, and the plasma toroidal flow are all fixed to ensure that the effects identified here are predominantly due to the plasma aspect ratio.

Drift kinetic theory of the NTM magnetic islands in a finite beta general geometry tokamak plasma

In (Imada et al 2019 Nucl. Fusion 59 046016 and references therein) a new 4D drift kinetic nonlinear theory, valid in the limit of a low beta, small inverse aspect ratio, circular cross section, toroidal geometry, to describe the plasma response to the neoclassical tearing mode (NTM) magnetic perturbation is derived. In (Dudkovskaia et al 2021 Plasma Phys. Control. Fusion 63 054001) this theory is reduced in a low collisionality limit, which allows a dimensionality reduction to a 3D problem to efficiently resolve the collisional dissipation layer in the vicinity of the trapped-passing boundary. (Dudkovskaia et al 2021 Plasma Phys. Control. Fusion 63 054001) adopts an improved model for the magnetic drift frequency, which reduces the threshold magnetic island half-width from , where is the trapped ion banana orbit width, to , making it in closer agreement with experimental observations for the large aspect ratio tokamak equilibrium. In the present paper, the theory is extended to a high beta, arbitrary tokamak geometry to capture the plasma shaping effects on the NTM threshold physics with the focus on the non-zero triangularity discharges that are known to have a strong impact on the plasma MHD stability. First, it is found that the higher triangularity plasma is more prone to NTMs which is in agreement with the tearing mode onset relative frequency measurements in DIII-D. Second, the NTM threshold dependence on the tokamak inverse aspect ratio obtained in (Dudkovskaia et al 2021 Plasma Phys. Control. Fusion 63 054001) is refined and extended to a finite aspect ratio limit. Third, the NTM threshold dependence on poloidal beta is obtained and benchmarked against the EAST threshold island width measurements.

Stochastic fluctuation and transport of tokamak edge plasmas with the resonant magnetic perturbation field

We present that a statistical method known as the complexity–entropy analysis is useful to characterize a state of plasma turbulence and flux in the resonant magnetic perturbation (RMP) edge localized mode (ELM) control experiment. The stochastic pedestal top temperature fluctuation in the RMP ELM suppression phase is distinguished from the chaotic fluctuation in the natural ELM-free phase. It is discussed that the stochastic temperature fluctuation can be originated from the narrow layer of the field penetration on the pedestal top. The forced magnetic island can emit the resonant drift wave of comparable sizes (relatively low-k) in the RMP ELM suppression phase, and it can result in the generation of stochastic higher wavenumber fluctuations coupled to tangled fields around the island. The analysis of the ion saturation current measurement around the major outer striking point on the divertor shows that it also becomes more stochastic as the stronger plasma response to the RMP field is expected.

Non-linear free boundary simulations of the plasma response to resonant magnetic perturbations in ASDEX Upgrade plasmas

A promising method for the control of Edge Localized Modes (ELMs) in H-Mode tokamak plasmas is the application of Resonant Magnetic Perturbations (RMPs), where small helical field perturbations are introduced into the plasma via a set of external coils. While RMPs are used for suppression of ELMs in many present-day tokamaks, the mechanisms that lead to RMP-ELM control are still subject of debate.Here, we use the non-linear MHD code JOREK to investigate the penetration of the magnetic perturbation fields into ASDEX Upgrade (AUG) plasmas. We present an extension of the coupled JOREK-STARWALL code, that replaces the commonly used fixed boundary treatment with a free boundary treatment. Instead of prescribing the magnetic field at the boundary according to the vacuum field using Dirichlet boundary conditions, natural boundary conditions are applied, so that the magnetic field and plasma current density are evolving freely at the boundary. This allows a fully self-consistent development of the plasma response and the magnetic perturbation in the whole computational domain. The direct comparison of both approaches demonstrates that the artificial suppression of the plasma response with the fixed boundary treatment reduces the excitation of marginally stable modes. An overall larger perturbation is observed using the free boundary approach.The presented simulations are performed in realistic geometry with fully realistic plasma parameters and plasma flows based on reconstructions of experimental AUG equilibria. While the use of realistic plasma parameters makes the simulations particularly challenging, it also allows for quantitative comparisons to the experiment. When the RMP induced corrugation of the boundary is compared to electron density measurements from the lithium beam emission spectroscopy, only the free boundary approach shows excellent agreement with the experiment.

Iterative approach to linear ideal MHD modeling of plasma response to 3D magnetic perturbations in tokamaks

The class of plasma instabilities known as edge-localized modes (ELMs) is of special concern in tokamaks operating in high-confinement mode, such as ASDEX Upgrade and ITER. One strategy for ELM mitigation is the application of resonant magnetic perturbations (RMPs) via external coils. Kinetic modeling accurately describes the plasma response to these RMPs ab initio, particularly the parallel shielding currents at resonant surfaces. Away from resonant surfaces, ideal magnetohydrodynamics (iMHD) is expected to yield sufficiently accurate results, providing a computationally less expensive option that could complement kinetic modeling.The code MEPHIT has been developed to solve the linearized iMHD equations in a way that is compatible with iterative kinetic modeling approaches. We consider an axisymmetric iMHD equilibrium in realistic tokamak geometry under the influence of a quasi-static non-axisymmetric external perturbation from ELM mitigation coils. The plasma responds to this external magnetic perturbation with a current perturbation, which in turn produces a magnetic field perturbation. The resulting fixed-point equation can be solved in a self-consistent manner by preconditioned iterations in which Ampère’s equation and the magnetic differential equations for pressure and current are solved in alternation until convergence is reached. After expansion in toroidal Fourier harmonics, these equations are solved on a triangular mesh in the poloidal plane using finite elements. These results are then benchmarked against established codes.

In Situ Space Plasma Diagnostics With Finite Amplitude Active Electric Experiments: Non‐Linear Plasma Effects and Instrumental Performance of Mutual Impedance Experiments

AbstractMutual impedance (MI) experiments are a kind of plasma diagnostic techniques for the identification of the in situ plasma density and electron temperature. These plasma parameters are retrieved from MI spectra, obtained by perturbing the plasma using a set of electric emitting antennas and, simultaneously, retrieving using a set of electric receiving antennas the electric fluctuations generated in the plasma. Typical MI experiments suppose a linear plasma response to the electric excitation of the instrument. In the case of practical space applications, this assumption is often broken: low temperature plasmas, which are usually encountered in ionized planetary environments (e.g., RPC‐MIP instrument onboard the Rosetta mission, RPWI/MIME experiment onboard the JUICE mission), force toward significant perturbations of the plasma dielectric. In this context, we investigate MI experiments relaxing, for the first time, the assumption of linear plasma perturbations: we quantify the impact of large antenna emission amplitudes on the (a) plasma density and (b) electron temperature diagnostic performance of MI instruments. We use electrostatic 1D‐1 V full kinetic Vlasov‐Poisson numerical simulations. First, we simulate the electric oscillations generated in the plasma by MI experiments. Second, we use typical MI data analysis techniques to compute the MI diagnostic performance in function of the emission amplitude and of the emitting‐receiving antennas distance. We find the plasma density and electron temperature identification processes robust (i.e., relative errors below 5% and 20%, respectively) to large amplitude emissions for antenna emission amplitudes corresponding to electric‐to‐thermal energy ratios up to .

Toroidal modeling of 3D perturbations generated by current filaments in scrape-off layer in tokamak with biased divertor targets

The divertor biasing technique offers a promising alternative to control the edge localized mode (ELM) as well as the divertor heat load in tokamaks, as compared to the resonant magnetic perturbation (RMP) generated by magnetic coils. The linear resistive MHD code MARS-F (Liu et al 2000 Phys. Plasmas 7 3681) is employed to study the plasma response to the n = 2 (n is the toroidal mode number) field perturbation in HL-2A, produced by the divertor biasing current filaments flowing in the scrape-off layer region. The response field due to biasing currents is compared with the RMP field utilized for ELM control in HL-2A. The strength of the radial resonant field perturbation, produced by the biasing currents of 100 A level, is found to be comparable with RMP generated by several kA of ELM control coil currents for the reference plasma. The plasma normal displacement near the X-point and the associated neoclassical toroidal viscosity torque are also computed to be similar between these two techniques. The modeling results thus strongly suggest that the biasing technique can be applied to control ELMs. Moreover, the biasing currents produce field perturbations, including the plasma response, that are localized more near the plasma edge (compared to the RMP counterpart), thus reducing the chance of mode locking associated with core perturbations. Particle orbit tracing also reveals that the biasing current produced magnetic perturbation tends to widen the heat deposition region and induce the strike point splitting of the ion saturation flow on the outer divertor surface, consistent with experimental observations in HL-2A. These toroidal modeling results confirm the possibility of ELM control and plasma exhaust solution by the divertor biasing technique.