Ion Cyclotron Resonance Frequency Research Articles

Self-consistent modelling of radio frequency sheath in 3D with realistic ICRF antennas

Abstract Ion Cyclotron Resonant Frequency (ICRF) induced impurity production has raised many concerns since ITER proposed to change the first wall material from beryllium to tungsten. Enhanced DC plasma potential (VDC) due to RF sheath rectification is well known as one of the most important mechanisms behind the RF induced impurities. Our previous work (L. Lu et.al, Plasma Phys. Control. Fusion 60 (2018) 035003) considered the impact of both the slow wave and the fast wave on the RF sheath rectification in a 2D geometry. It can barely recover the double-hump structure of the VDC poloidal distribution observed in various machines when only the slow wave is modelled using the multi-2D approach which intrinsically assumes the poloidal wavenumber kz is zero. The fast wave on the other hand is found to be more sensitive to a finite kz and may need to be tackled in 3D. This work reports our recent progress on the 3D RF sheath modelling. In this new code, the latest RF sheath boundary conditions (J. R. Myra, J. Plasma Phys. 87 (2021) 905870504) and the realistic 3D ICRF antennas are implemented. Compared to the 2D results, the 3D code could well recover the double-hump poloidal distribution of VDC even with the fast wave included, which confirms our speculation on the necessity of treating the fast wave in 3D. While the double-hump pattern is robust in the simulation, the amplitude of VDC is found to be affected by the magnetic tilt angle and the antenna geometry. This emphasizes the importance of adopting a realistic antenna geometry in the RF sheath modelling. The double-hump VDC poloidal structure breaks as the magnetic tilt angle increases. This is explained by the gyrotropic property of the cold plasma dielectric tensor. The spatial proximity effect we identified in the previous 2D simulations is still valid in 3D. Finally, simulation shows the slow wave dominates the RF sheath excitation in the private SOL, while the fast wave gradually takes over when moving to the far SOL region. This code could be a new tool to provide numerical support for ITER impurity assessment and ICRF antenna design.

Modeling of ion cyclotron resonance frequency heating of proton-boron plasmas in EHL-2 spherical tokamak

Ion cyclotron resonance heating (ICRH) stands out as a widely utilized and cost-effective auxiliary method for plasma heating, bearing significant importance in achieving high-performance discharges in p-11B plasmas. In light of the specific context of p-11B plasma in the EHL-2 device, we conducted a comprehensive scan of the fundamental physical parameters of the antenna using the full-wave simulation program TORIC. Our preliminary result indicated that for p-11B plasma, optimal ion heating parameters include a frequency of 40 MHz, with a high toroidal mode number like to heat the majority H ions. In addition, we discussed the impact of concentration of minority ion species on ion cyclotron resonance heating when 11B serves as the heavy minority species. The significant difference in charge-to-mass ratio between boron and hydrogen ions results in a considerable distance between the hybrid resonance layer and the tow inverted cyclotron resonance layer, necessitating a quite low boron ion concentration to achieve effective minority heating. We also considered another method of direct heating of hydrogen ions in the presence of boron ion minority. It is found that at appropriate boron ion concentrations ( ), the position of the hybrid resonance layer approaches that of the hydrogen ion cyclotron resonance layer, thereby altering the polarization at this position and significantly enhancing hydrogen ion fundamental absorption.

Numerical simulations on loss of ICRF-heated NBI ions in EAST

The loss of ion cyclotron resonance frequencies (ICRF)-heated neutral beam injection ions in experimental advanced superconducting tokamak was numerically investigated by ORBIT code simulations. The effects of collisions and ripples on particle losses were taken into account, and the distributions of fast ions generated by different beams in combination with ICRF heating were calculated using the TRANSP code. Results showed that ICRF waves altered the orbital distributions of beam ions, causing an increase in trapped ions and fast ion losses. Additionally, for co-current injected beams, perpendicular injection resulted in higher fast ion losses in synergistic heating than tangential injection. The study also found that the synergistic effect of collisions and ripples enhanced fast ion losses, which were highly localized and generated a maximum heat load of 0.165 MW m−2 on the first wall. However, conducting synergy heating experiments at high plasma currents and low effective ion charge numbers can significantly reduce the loss of fast ions.

THE DICHOTOMY OF THE MECHANISMS OF DECAMETER RADIO EMISSION FROM JUPITER: THE INFLUENCE OF STREAMER INHOMOGENEITIES AND MHD PERTURBATIONS IN THE SOURCE

There are analyzed a model of the source of DAM radiation bursts which are activated under the MHD waves excitation in the Jupiter lower magnetosphere in a presence of ionized streamer-like inhomogeneities of limited thickness (1-100 km). There was studied the formation of an anisotropic kinetic distribution of electrons, which leads to the generation of Jupiter DAM radiation bursts under the various scenarios. It was investigated the influence of gas-dust flows in the Io-Jupiter tube, the ionization processes and the diffusion effects in the streamer plasma to the creation the cone-type kinetic distribution of electrons. On the other hand, it has been shown that Alfven waves, due to the fluctuations of electric fields, are to form of both cone-like electron distribution (primarily on the streamer periphery) and beam-like distribution with the beams of accelerated electrons (primarily inside the streamer), which further run along the streamers at speeds of about 0.1c and have been modulated by a "longitudinal" MHD wave with a length of about 1000 km and a period of about 1 second. The streamer oscillations in the direction tangential to the magnetic field lines lead to the excitation the fast magneto-sonic waves (at about the ion cyclotron resonance frequencies). The beams of accelerated electrons of along the magnetic field lines generate the plasma waves in the same direction (at about the electron cyclotron resonance frequency). At the same time, plasma perturbations create a stratification of the steamer-tube structure into ultrafine threads of ionized plasma, and they contribute to the ultrafine modulation of bursts of DAM radiation with millisecond periods. Finally, it is shown in detail how all these processes lead to activate the Jupiter DAM radiation bursts in that source at the frequency of electron cyclotron resonance by different generation mechanisms, such as the Maser Cyclotron or Cherenkov mechanisms of generation, and with different burst’s properties.

Experiments in high-performance JET plasmas in preparation of second harmonic ICRF heating of tritium in ITER

The reference ion cyclotron resonance frequency (ICRF) heating schemes for ITER deuterium–tritium (D-T) plasmas at the full magnetic field of 5.3 T are second harmonic heating of T and 3He minority heating. The wave-particle resonance location for these schemes coincide and are central at a wave frequency of 53 MHz at 5.3 T. Experiments have been carried out in the second major D-T campaign (DTE2) at JET, and in its prior D campaigns, to integrate these ICRF scenarios in JET high-performance plasmas and to compare their performance with the commonly used hydrogen (H) minority heating. In 50:50 D:T plasmas, up to 35% and 5% larger fusion power and diamagnetic energy content, respectively, were obtained with second harmonic heating of T as compared to H minority heating at comparable total input powers and gas injection rates. The core ion temperature was up to 30% and 20% higher with second harmonic T and 3He minority heating, respectively, with respect to H minority heating. These are favourable results for the use of these scenarios in ITER and future fusion reactors. According to modelling, adding ICRF heating to neutral beam injection using D and T beams resulted in a 10%–20% increase of on-axis bulk ion heating in the D-T plasmas due to its localisation in the plasma core. Central power deposition was confirmed with the break-in-slope and fast Fourier transform analysis of ion and electron temperature in response to ICRF modulation. The tail temperature of fast ICRF-accelerated tritons, their enhancement of the fusion yield and time behaviour as measured by an upgraded magnetic proton recoil spectrometer and neutral particle analyser were found in agreement with theoretical predictions. No losses of ICRF-accelerated ions were observed by fast ion detectors, which was as expected given the high plasma density of n e ≈ 7–8 × 1019 m−3 in the main heating phase that limited the formation of ICRF-accelerated fast ion tails. 3He was introduced in the machine by 3He gas injection, and the 3He concentration was measured by a high-resolution optical penning gauge in the sub-divertor region. The DTE2 experiments with 3He minority heating were carried with a low 3He concentration in the range of 2%–4% given the fact that the highest neutron rates with 3He minority heating in D plasmas were obtained at low 3He concentrations of ∼2%, which also coincided with the highest plasma diamagnetic energy content. In addition to 3He introduced by 3He gas injection, an intrinsic concentration of 3He of the order of 0.2%–0.4% was measured in D-T plasmas before 3He was introduced in the device, which is attributed to the radioactive decay of tritium to 3He. According to modelling, even such low intrinsic concentrations of 3He lead to significant changes in ICRF power partitioning during second harmonic heating of T due to absorption of up to 30% of the wave power by 3He.

Tritium removal from JET-ILW after T and D–T experimental campaigns

After the second Deuterium–Tritium Campaign (DTE2) in the JET tokamak with the ITER-Like Wall (ILW) and full tritium campaigns that preceded and followed after the DTE2, a sequence of fuel recovery methods was applied to promote tritium removal from wall components. The sequence started with several days of baking of the main chamber walls at 240 °C and at 320 °C. Subsequently, baking was superimposed with Ion-Cyclotron Wall Conditioning (ICWC) and Glow Discharge Conditioning (GDC) cleaning cycles in deuterium. Diverted plasma operation in deuterium with different strike point configurations, including a Raised Inner Strike Point (RISP) configuration, and with different plasma heating—Ion Cyclotron Resonance Frequency (ICRF) and Neutral Beam Injection (NBI)—concluded the cleaning sequence. Tritium content in plasma and in the pumped gas was monitored throughout the experiment. The applied fuel recovery methods allowed reducing the residual tritium content in deuterium NBI-heated plasmas to about 0.1% as deduced from neutron rate measurements. This value is well below the requirement of 1% set by the maximum 14 MeV fusion neutron budget allocated in the ensuing deuterium plasma campaign. The quantified tritium removal over the course of the experiment was 13.4±0.7×1022 atoms or 0.67±0.03 g with ∼58% attributed to baking, ∼12.5% to ICWC, ∼26% to GDC, and ∼3.5% to first low power RISP plasmas. The experimentally estimated amount of removed tritium is in good agreement with long-term tritium accounting by the JET tritium reprocessing plant, in which the unaccounted amount was reduced by 0.71 g after the cleaning experiment.

Use of intrinsic hysteresis for the active control of internal transport barriers in magnetically confined fusion plasmas

In magnetically confined fusion devices, control of internal transport barriers (ITBs) is important both to enhance and suppress the turbulent transport to improve confinement control. Barrier control should allow for the improvement of confinement to aid in achieving the needed fusion criteria while also permitting the degradation of confinement to control profiles and clean the device by moving out the impurities accumulated near the core. In this work, we present a novel control scenario that takes advantage of the hysteresis intrinsic to transport barriers to easily cycle through enhanced and degraded confinement regimes. The control scenario is illustrated using a five-field simplified transport model for an ITB using typical parameters of a neutral beam injection-heated DIII-D tokamak discharge. Pellets and ion cyclotron resonance frequency power are used as control knobs for this active control scenario. These knobs adequately modify at will the local gradients and, therefore, the growth rates and shearing rates, allowing for easy and efficient control of the barrier by taking advantage of the barrier hysteresis. The result is a control cycle that could be operated with a relatively small amount of power in high performance regimes which, nowadays, typically require large power to control. It may also have advantages to avoid, or at least ameliorate, the appearance of magnetohydrodynamic instabilities in the barrier region.

Large Volume and Fast Response Gamma Ray Diagnostic in the Large Helical Device

A large volume and fast response gamma ray diagnostic based on the LaBr3(Ce) scintillator was installed to obtain the gamma ray spectrum in the Large Helical Device (LHD) for understanding energetic ion confinement. The advantages of the LaBr3(Ce) scintillator are relatively sensitive to gamma rays due to its relatively heavy weight density of 5.3 g/cc, high counting operation because of a relatively short pulse width of ∼100 ns, and relatively better energy resolution of ∼3%. The gamma ray diagnostic was installed at the outboard side of LHD. The radiation shielding for the LaBr3(Ce) detector was designed to avoid unwanted signals due to stray neutrons and gamma rays using the three-dimensional radiation transport calculation MCNP6. In-situ energy calibration of the LaBr3(Ce) detector was performed using 60Co and 137Cs gamma ray sources. We surveyed a neutron effect on the LaBr3(Ce) detector in an electron-cyclotron-heated deuterium plasma discharge. The pulse counting rate of LaBr3(Ce) detector under the total neutron emission rate of 2×1011 n/s was 110 kcps. Therefore, the LaBr3(Ce) detector is expected to be utilized in most of ion cyclotron resonance frequency (ICRF) discharges, where the total neutron emission rate of ∼1011 n/s. We plan to measure the gamma ray spectrum in deuterium ICRF discharges.

Investigation of the synergistic effects of ICRF + NBI heating in EAST plasma discharges

Following an upgrade of the neutral beam injection (NBI) system, obvious synergy between combined NBI and ion cyclotron resonance frequency (ICRF) heating was observed in recent experiments conducted at EAST. To investigate the effects of beam-ions accelerated by radiofrequency (RF) wave, analyses are performed by using TRANSP code based on the experimental results. The calculated results argue that only a small fraction of the ICRF power is absorbed by the beam ions in the ICRF + NBI synergistic heating of the (H)D plasma. To enhance the beam–RF interactions in synergistic heating and achieve high plasma performance of EAST, different experimental conditions, including multiple injection powers and diverse beam injection options, were explored. Beam injected fast ions are passing particles, trapped particles observed when synergy heating between ICRF and NBI. In particular, by varying the injection direction of the beam ions it was observed that more tangential beam yields better synergy in comparison with more perpendicular beam. The neutron emission rate of D–D fusion in tokamaks is improved and less fast ion loss is produced with tangential NBI + ICRF heating. Also, the effect of the ratio P ICRF/P NBI on ICRF + NBI combined heating is demonstrated, the higher power boosts the fusion enhancement. The study of the performed synergistic heating provides an important reference for the subsequent combined NBI + ICRF heating experiments on EAST.

Ku-band multichannel frequency comb Doppler reflectometer on the GAMMA 10/potential control and divertor simulating experiment (PDX) tandem mirror.

A Ku-band (12-18GHz) multichannel Doppler reflectometer (DR) has been developed in the GAMMA 10/potential control and divertor simulating experiment (PDX) tandem mirror device to improve the applicability of DR measurement for simultaneous monitoring of velocity of electron density turbulence at different locations. Our previous single-channel DR circuit has been replaced by the multichannel microwave system using a nonlinear transmission line based comb generator with heterodyne technique. The multichannel DR system has been installed in the central cell of GAMMA 10/PDX. Initial results of application to GAMMA 10/PDX plasma are presented, showing Doppler frequency shifts during an additional ion cyclotron resonance frequency heating and gas-puffing experiment.

Recent EAST Experimental Results and Systems Upgrade in Support of Long-Pulse Steady-State Plasma Operation

In recent years, EAST has achieved a 60-s scale steady-state plasma operation (SSO), which is electron dominant heated by the electron cyclotron wave and low hybrid wave. Substantial progresses have been made in the development of long-pulse operation, such as active control of radiative divertor, edge localized mode (ELM) suppression, and He plasma experiment. To further develop the steady-state operation scenario and study the related critical physical issues, the upgrade of EAST has been completed in 2020. The auxiliary heating systems were rearranged and upgraded with a total heating power capability of 33 MW. The 2.45-GHz lower hybrid current drive (LHCD) launcher has been updated from full active multijunction (FAM) to passive active multijunction (PAM) to avoid damage caused by plasma–material interaction. The injection power capability of electron cyclotron resonance heating (ECRH) system is upgraded to 1.4 MW. The upgraded ion cyclotron resonance frequency (ICRF) antenna injects low parallel wavenumber ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$k_{\vert \vert }$ </tex-math></inline-formula> ) spectra with good single pass absorption. The neutral beam injection (NBI) system is moved from F-port to D-port and is reoriented from counterclockwise to clockwise injection. The armor material of lower divertor has been upgraded from graphite to tungsten improving the steady-state heat handling capability from 2 to 10 MW/m2. Based on the upgraded pumping system and improved conductance, the effective pumping speed for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$D_{2}$ </tex-math></inline-formula> of the EAST lower divertor increased twice. With all these upgrades, 100-s scale steady-state operation ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{e0} &gt;10$ </tex-math></inline-formula> keV) and 1056-s high-performance operation with 1.73-GJ injection energy were achieved in 2021 campaigns. The experience in high-performance long-pulse operation obtained on EAST will lay a foundation for the ITER and Chinese Fusion Engineering Testing Reactor (CFETR) operation.

Development of high power 20 dB directional coupler for Ion Cyclotron Resonance frequency system of Tokamak

This article presents the design and fabrication of 20± 0.3dB directional coupler having 2kW power handling capability in the frequency range of 140-200MHz. The developed coupler has an important application in the prototype of the Ion Cyclotron Resonance Frequency (ICRF) system of Tokamak. The directional coupler used to couple the forward and reflected power for measurement and provide the feedback to the existing matching network responsible for protecting the high power RF source. The prototype ICRF system has been developed to test the matching speed of the ICRF system for load resilient operation. The developed coupler is compact in size, robust, and capable of handling 2kW, continuous wave (cw) RF power. This paper also analyses the dielectric breakdown strength using electric field distribution inside the coupler and the average power handling capability is determined using numerical analysis. The test and simulation results of developed coupler are found in good agreement. The test results using Vector Network Analyzer (VNA) are obtained as, the coupling flatness of 20 ± 0.3 in 140-200 MHz frequency range, return loss and isolation are -30dB and -35dB respectively. The work presented in this paper is helpful for the design and development of high power coupler in radio frequency (RF) range and may be applied in various applications such as RF Plasma, Radar, navigation, satellite and research etc.

Theoretical Study of the Impedance Matching of the Ferrite Tuner System for ICRF Heating

A theoretical study on a ferrite stub tuner antenna system for ion cyclotron resonance frequency (ICRF) heating is discussed in this paper. High amounts of radio frequency power can be reflected at the antenna as a result of impedance mismatches arising from large changes in the plasma resistance during L- to H-mode transitions or edge localized modes. A fast-response ferrite stub tuner network has been proposed to mitigate these reflections by rapidly varying the impedance to match the rapid load changes on the ICRF antenna. This study numerically shows the influence relationship of the normalized mechanical length and the ratio of the ferrite part of two ferrite stubs on the regulating range of a biasing magnetic field of two stubs. A prematching stub can be used to reduce the standing-wave voltage on the ferrite tuners. The analysis of the ideal position and length of the prestub as well as the distance between the ferrite network and prestub are presented. Numerical simulations demonstrate that selecting ideal values for mechanical length and the ratio of the ferrite part of two ferrite stubs plays an important role in the impedance matching performance of the triple ferrite system during a large variation in plasma resistance.

Simultaneous H/D/T and 3He/4He absolute concentration measurements with an optical Penning gauge on JET

The Optical Penning (or Species-Selective Penning) Gauge technique is used for the measurement of the H2/D2/T2 fuel isotopic composition and He/D2 concentration in the neutralized particle exhaust of fusion devices. An Optical Penning detection system has already been used in JET during its first deuterium-tritium campaigns (DTE1) and has been chosen by ITER. Recent improvements to the sub-divertor diagnostic suite as well as the optical instrumentation, in preparation for the next DT campaign, have improved the optical throughput of the measurement and enabled 3He/D2 detection down to 0.1 %. For the first time, the 3He/4He isotopic ratio can be measured simultaneously with the H/D/T ratio. This technique is of particular interest for ion cyclotron resonance frequency (ICRF) heating scenarios.

Estimation of Power Transmission of Fast Wave in ICRF Range Through Tokamak Plasma Edge with the Help of Reflection Coefficient

The capability of measurement of the power transfer of a fast wave in the ion cyclotron resonance frequency range through the tokamak plasma edge has been shown with the help of measurement of the complex reflection coefficient. Optimization of the antenna position and the feasibility of calculating the antenna structure have also been discussed.

Generation and observation of fast deuterium ions and fusion-born alpha particles in JET plasmas with the 3-ion radio-frequency heating scenario

Dedicated experiments to generate energetic D ions and fusion-born alpha particles were performed at the Joint European Torus (JET) with the ITER-like wall (ILW). Using the 3-ion radio frequency (RF) heating scenario, deuterium ions from neutral beam injection (NBI) were accelerated in the core of mixed plasmas to higher energies with ion cyclotron resonance frequency (ICRF) waves, in turn leading to a core-localized source of alpha particles. The fast-ion distribution of RF-accelerated D-NBI ions was controlled by varying the ICRF and NBI power ( 4–6 MW, 3–20 MW), resulting in rather high D-D neutron (≈ 1 × 1016 s−1) and alpha rates (≈ 2 × 1016 s−1) at moderate input heating power. Theory and TRANSP analysis shows that large populations of co-passing MeV-range D ions were generated using the 3-ion ICRF scenario. This important result is corroborated by several experimental observations, in particular gamma-ray measurements. The developed experimental scenario at JET provides unique conditions for probing several aspects of future burning plasmas, such as the contribution from MeV range ions to global confinement, but without introducing tritium. Dominant fast-ion core electron heating with and a rich variety of fast-ion driven Alfvén eigenmodes (AEs) were observed in these plasmas. The observed AE activities do not have a detrimental effect on the thermal confinement and, in some cases, may be driven by the fusion born alpha particles. A strong continuous increase in neutron rate was observed during long-period sawteeth (1 s), accompanied by the observation of reversed shear AEs, which implies that a non monotonic q profile was systematically developed in these plasmas, sustained by the large fast-ion populations generated by the 3-ion ICRF scenario.

Turbulence Suppression by Energetic Particle Effects in Modern Optimized Stellarators.

Turbulent transport is known to limit the plasma confinement of present-day optimized stellarators. To address this issue, a novel method to strongly suppress turbulence in such devices is proposed, namely the resonant wave-particle interaction of suprathermal particles-e.g., from ion-cyclotron-resonance-frequency heating-with turbulence-driving microinstabilities like ion-temperature-gradient modes. The effectiveness of this mechanism is demonstrated via large-scale gyrokinetic simulations, revealing an overall turbulence reduction by up to 65% in the case under consideration. Comparisons with a tokamak configuration highlight the critical role played by the magnetic geometry and the first steps into the optimization of fast particle effects in stellarator devices are discussed. These results hold the promise of new and still unexplored stellarator scenarios with reduced turbulent transport, essential for achieving burning plasmas in future devices.

Stimulation and inhibition of respiratory burst in neutrophils as a result of action of weak combined magnetic fields adjusted to ICR of protonated water forms

ABSTRACT Weak combined collinear magnetic fields (CMFs) composed of constant component, 60 μT and low-frequency alternating field, 100 nT, used in 40 min pretreatment, were shown to have diverse effects (alleviation/stimulation) depending on the frequency of the alternating component on respiratory burst intensity in neutrophil suspension after activation by N-formyl-Met-Leu-Phe recorded by luminol-dependent chemiluminescence. About 12.6 Hz frequency formally corresponding to ion cyclotron resonance (ICR) frequency of hydrated hydronium ion (Н9О4 +) had notable stimulating effect. On the contrary, treatment with 48.5 Hz frequency corresponding to hydronium ion (Н3О+) was accompanied by significant alleviation of respiratory burst intensity. CMFs-pretreated water conducted only stimulating effect of CMFs when the field was adjusted to ICR of hydrated hydronium ion form, which is direct proof of participation of water in the mechanism of this effect of CMFs.

Design of a multi-voltage probe system for ICRF antenna coupling resistance measurement on EAST

A multi-voltage probe array system is designed to measure the coupling resistance of an ion cyclotron resonance frequency antenna. In the process of the antenna coupling resistance data extraction, the minimization algorithm, the original Levenberg–Marquardt algorithm, is replaced by the Broyden–Fletcher–Goldfarb–Shanno algorithm to achieve more stable and accurate results. Moreover, a simple model of the multi-voltage probe array was applied to simulate the performance of the Kalman filter, and to optimize the distance and position of the probes and probe number to mitigate the influence of the system noise on the rebuilt results. During the EAST experiment in 2019, a four-voltage probe array was applied to measure the coupling resistance of line 6 during high confined mode discharge. The measurement results by the multi-voltage probe array system and the voltage/current probe pair show a good agreement.

The Role of Water in the Effect of Weak Combined Magnetic Fields on Production of Reactive Oxygen Species (ROS) by Neutrophils

Various models have been used to demonstrate the pronounced effects of the microwave frequency range electromagnetic fields, as well as weak and very weak combined collinear magnetic fields (CMF) with static and variable components in the order of micro- and nano-tesla. One of such models, previously shown to be sensitive to variations in the parameters of applied magnetic fields, is the neutrophil respiratory burst. Using luminol-enhanced cell chemiluminescence assay, we studied the effects of the CMF exerted directly on neutrophil suspensions and, indirectly, through aqueous solutions. To experimentally create a uniform standard weak CMF with 60 µT static and 100 nT alternating magnetic field components, we engineered a shielded magnetic field induction device. CMF applied directly to neutrophils enhanced reactive oxygen species (ROS) production by more than 36%. The pronounced stimulating effect was observed only when using the signals that included the frequency of 12.6 Hz that corresponds to the ion cyclotron resonance (ICR) frequency of the hydrated hydronium ion. Similarly, to direct exposure, CMF pre-treatment of a water sample subsequently added to the neutrophil suspension increased ROS production by 66%. The effect of CMF pre-treatment was retained after a series of dilutions and mechanical treatment but disappeared in “magnetic vacuum” or without mechanical influence. Therefore, weak and super weak magnetic fields may indirectly, via water, activate ROS production by neutrophils, provided that modulation of super weak component of collinear field corresponds to the ICR frequency of the hydrated hydronium ion.