Electron Plasma Research Articles

Characterization of the SCR-1 Stellarator Physics: Investigating Plasma Discharge, MHD Equilibrium Calculations, and O-X-B Mode Conversion Feasibility

Abstract The Stellarator de Costa Rica 1 (SCR-1) is a small modular stellarator that serves as a valuable research and training tool for plasma magnetic confinement. This study aimed to analyze the characteristics of SCR-1, including its peripheral systems, technical plasma discharge processes, and advancements in plasma characterization. In addition, this study explored a new heating mechanism and the factors that influence it. The current state of the device and plasma discharge are initially presented. Subsequently, the measurement process was utilized to determine the electronic density and plasma temperature using a single Langmuir probe and the results were compared with theoretical predictions based on the particle and energy balance. Additionally, the VMEC code was employed to calculate magnetic flux surfaces with characteristics such as a low aspect ratio, low beta parameter, negative magnetic shear, and decreasing rotational transform along magnetic flux surfaces. The Mercier criterion was employed to conduct a linear stability analysis, which identified a magnetic well that played a crucial role in the linear stability of the majority of magnetic flux surfaces. Feasibility studies of electron Bernstein waves were conducted using the IPF-FMDC full-wave code. The results obtained from the IPF-FMDC code revealed that the O-X conversion percentage reached a maximum of 63 % when considering radiation reflection in the vacuum vessel. Significant effects of plasma curvature on the O-X wave conversion and normalized electron density scale length were observed, while the change in the SCR-1 heating position did not produce a significant impact. Three damping mechanisms affecting O-X conversion were studied, and one of the principal effects was the SX-FX conversion due to steep electron density gradient. Additionally, stochastic electron heating showed a low electron field amplitude, which is important for limiting the electron Bernstein wave propagation.

Use of tenofovir-based PrEP among pregnant women in South Africa.

We developed Healthy Families-PrEP to support perinatal women to use HIV prevention strategies. Single arm study to evaluate PrEP use among pregnant women exposed to the intervention. We offered safer conception counselling including TDF/FTC as PrEP with adherence support (Healthy Families-PrEP) for women planning for pregnancy in South Africa with a partner with HIV or unknown serostatus. Women completed pregnancy and HIV testing quarterly and were followed for one year or until pregnancy end. For those initiating PrEP, electronic pillcap data and plasma were collected. We described PrEP adherence by proportion of days with pillcap openings and proportion of women with detected (≥10ng/mL) plasma tenofovir. From November 2017 to January 2020, 326 women with median age 24 (IQR: 22-27) years enrolled. Partner HIV-serostatus was unknown by 316 (97%). Over 3,204 person-months of follow-up, 56 women became pregnant. Twenty-six women used PrEP during pregnancy and opened pillcaps on a mean of 53.1% (95% CI 46.9-59.3%) of days. Plasma tenofovir was detected among 25.0%, 15.4%, and 12.5% of women providing samples during months 0-3, 4-6, and 7-9. No HIV seroconversions were observed. We observed low pregnancy incidence. Counselling may have encouraged delayed pregnancy plans; some women may have exaggerated pregnancy plans to enroll. About half of pregnant women used PrEP and took over half of doses by pillcap. Fewer than 25% had tenofovir detected, likely reflecting pregnancy-related pharmacokinetics and adherence challenges. High interest in pregnancy PrEP use highlights the need to optimize adherence support and prevention choice.

Modulation of self-focusing and plasma wave dynamics by ripple on hollow gaussian beams

Abstract This study investigates the propagation of a hollow Gaussian beam (HGB) through a collisionless plasma medium containing superimposed ripples, incorporating relativistic nonlinear effects. The Wentzel-Kramers-Brillouin (WKB) paraxial ray approximation and the eikonal method are employed to derive governing equations for the self-focusing of the main beam, the ripples, and the excitation of plasma waves under these conditions. Our analysis demonstrates that the presence of ripples significantly alters the propagation dynamics of HGBs and influences the excitation of electron plasma waves (EPWs). The order and phase angle of ripples influence the main beam dynamics and EPW propagation. Both the HGB order and ripple order affect the ripple dynamics and EPW power. The various orders of the HGB and the angle between the ripple and the main beam affect the ripple’s focusing behavior. These factors collectively influence the intensity of the excited plasma wave. Our findings contribute to a deeper understanding of laser-plasma interactions involving pre-existing ripples on HGB.

Estimation of the drift velocity of Equatorial Plasma Bubbles using GNSS and digisonde data

Equatorial Plasma Bubbles (EPBs) play a crucial role in modulating plasma density and electron content within the equatorial ionosphere. In this work, we present an advanced and more robust version of the method developed by \citet{Blanch2018} for detecting EPBs using data from the Global Navigation Satellite System (GNSS). The enhancements introduced in this version significantly improve the EPB detection process, achieving a notable reduction in the false positive rate compared to the previous approach. These refinements include the application of more rigorous statistical techniques to achieve a more accurate fit for the background Total Electron Content (TEC), leading to better characterization of EPBs through improved estimation of disturbance shapes. Applying the capabilities of this new method in a dense network of GNSS sensors, we have developed an interferometric procedure for estimating EPB drift velocities, including both speed and direction. This procedure provides valuable insights into the dynamic behavior of EPBs in the Caribbean region during 2014. Our analysis reveals a predominant eastward propagation pattern of EPBs, closely aligned with modified dip isolines. Furthermore, by integrating the results from the GNSS-based method with quasi co-located digisondes, we applied a conceptual model to estimate EPB velocities along their drift direction. This model has been tested across different geographical sectors and validated through comparisons with results from other independent studies. This cross-verification confirms the reliability of the methods for capturing EPB characteristics. This approach improves the precision of EPB detection and contributes to a deeper understanding of their spatiotemporal dynamics and behavior, providing a valuable framework for characterizing these phenomena in the equatorial ionosphere.

Small amplitude ion-acoustic waves in electron-ion dusty plasma: Landau damping effects of combined Kappa–Cairns distributed electrons

Small amplitude ion-acoustic waves in electron-ion dusty plasma: Landau damping effects of combined Kappa–Cairns distributed electrons

Impurity study in the dimensionless and dimensional isotope identity experiment between JET Deuterium and Tritium L-mode plasmas

Abstract The behaviour of impurities in fusion plasmas is of crucial importance for achieving sustained fusion reactions, and understanding similarities and differences between Deuterium (D) and Tritium (T) plasmas is needed to assess potential changes from DD to DT in ITER and future reactors. The first dimensionless and dimensional isotope identity experiments between Deuterium (D) and Tritium (T) L-mode plasmas were conducted at the JET W/Be wall. In the first approach, the discharges with matched ρ∗, ν∗, βn, q, and Te/Ti were compared to emphasize direct isotope effects, while in the dimensional approach engineering parameters such as toroidal magnetic field BT, plasma current Ip, plasma electron density and NBI power PNBI were matched. The dimensionless isotope scaling showed an improvement in global confinement and local transport in T plasmas in comparison to the matched D one [1]. Detailed impurity analyses using VUV, visible spectroscopy, SXR cameras, and bolometry revealed that T plasmas exhibited higher radiation and impurity content, particularly Ni and W, compared to D plasmas. Understanding the origin of the increased impurity content is addressed in this paper. The dimensionless experiments showed differences in impurity transport. The Be source behaviour varied: D plasmas had higher Be influx in the dimensionless approach due to lower electron density and enhanced sputtering [2], while T plasmas showed a higher Be source in the dimensional experiments, highlighting isotope mass effects. W in the divertor region was not sputtered by hydrogen isotopes. W in the divertor region was not sputtered by hydrogen isotopes. In the dimensionless experiments, W sputtering was primarily influenced by Ni in T plasmas and by Be in D plasmas. However, in the dimensional approach, Be played a more significant role in W sputtering within T plasmas. MHD instabilities, including sawtooth oscillations, were present in all cases other ones were correlated with NBI power levels; higher NBI power led to elevated levels of Be, Ni, and W impurities. The comprehensive comparison underscores the necessity of accounting for isotope mass effects in predictive modelling and optimization of plasma performance in fusion reactors.

Measurement of plasma characteristic parameters of copper foil explosion using interferometry

The accurate testing of plasma temperature and electron density and shock wave pressure during an electroburst in a copper foil transducer is critical for the characterization of the detonation performance of its elements. In this paper, the sequence of interferograms during the detonation of a copper foil transducer is captured at a frame rate of 3×106fps in conjunction with Mach–Zehnder interferometry and high-speed photography, and the results clearly demonstrate the propagation of the shock wave wavefront and plasma. The phase differences disturbed by plasma are extracted using the Fourier transform method, and the refractive index distributions are reconstructed with the Abel algorithm. Subsequently, based on the refractive index models of the shock wave and plasma, the shock wave pressure and plasma temperature and electron density are partitioned and reconstructed. Results show that the maximum shock wave pressure in the detonation of the copper foil transducer element is 1.297 atm, the maximum plasma temperature is 16,280 K, and the maximum plasma electron density is 2.134×1017cm−3. This study provides a theoretical and technical foundation for the detonation performance testing of pyrotechnic energy-conversion components.

Fabrication of Orientation-Controlled Fluorine-Doped SnO2 Film Grown By Atmospheric Spray Pyrolysis

Wide bandgap oxide semiconductors are attracting attention for applications such as optical devices, liquid crystal displays, and solar cells. In particular, Sn-doped In2O3 (ITO) is the most widely used transparent conductive oxide (TCO) material. Recently, due to the problem of decreasing indium resources, ZnO has been investigated as an alternative TCO material. Similarly, F-doped SnO2 (FTO) has been investigated in gas sensors, photovoltaic solar energy conversion devices, and electrochromic devices. FTO is an n-type semiconductor with a tetragonal structure similar to the rutile structure and a wide energy gap. Although various dopants are possible, films doped with fluorine exhibit high transparency and good conductivity. Many techniques have been used to prepare SnO2 thin films, including radiofrequency magnetron sputtering, chemical vapor deposition, metal-organic chemical vapor deposition, sol-gel methods, and spray pyrolysis. Spray pyrolysis is attractive for thin film growth because plasma damage to the substrate is avoided, high vacuum is not required, and equipment costs are low. However, there are not many papers on the FTO grown by spray pyrolysis. In our previous work [1], FTO films were successfully grown on glass substrates by the spray pyrolysis at 500 °C. The (200) orientation became strong with increasing fluorine concentration. In addition, F-doping caused the resistivity to decrease and the carrier concentration to increase. The lowest resistivity, 1.4 × 10-3 Ω cm, was obtained at a fluorine concentration of 4 mol%. Its carrier concentration and mobility were 6.2 × 1020 cm-3 and 7 cm2 V-1 s-1, respectively. Furthermore, the average optical transmittance in the visible region was nearly constant (at more than 80%) with increasing fluorine concentration. In this study, FTO films with various thicknesses (70 - 1550 nm) were successfully grown on glass substrates by spray pyrolysis method below 500 °C under atmospheric atmosphere. All the peak positions of XRD spectrum of the synthesized FTO film were in good agreement with the peak positions of ICDD. Furthermore, no fluorine related signals were observed in the spectra. The three-dimensional growth was associated with an increase in both grain size and film thickness and a change in orientation from (110) to (101) and (200). The preferred orientation of FTO changed at a film thickness of approximately 600 nm. It was considered to be influenced by the critical film thickness. Additionally, as the film thickness increased, the transmittance in the infrared region decreased. This was due to the absorption of free carriers at the electron plasma frequency within the film. The resistivity showed a tendency to decrease as the film thickness increased. On the other hand, the carrier concentration remained constant, but the mobility increased with increasing film thickness. This meant that the grain boundary scattering due to increasing grain size was dominant. Carrier concentration, surface structure, and film thickness were important factors in solar cells. In this study, the IR absorption increased despite the carrier concentration being constant. This result implied that at a constant high carrier concentration, the absorption was enhanced by increasing the film thickness. [1] M. Oshima and K. Yoshino: J. Electron. Mater. 39 (2010) 819.

Interaction of driven ‘cold’ electron plasma wave with thermal bulk via ion spatial inhomogeneity

Abstract Using high resolution Vlasov - Poisson simulations, evolution of driven ``cold" electron plasma wave (EPW) in the presence of stationary inhomogeneous background of ions is studied. Mode coupling dynamics between ``cold'' EPW with phase velocity $v_{\phi}$ greater than thermal velocity i.e $v_{\phi} \gg v_{thermal}$ and its inhomogeneity induced sidebands is illustrated as an initial value problem. In driven cases, formation of BGK like phase space structures corresponding to sideband modes due to energy exchange from primary mode to bulk particles via wave-wave and wave-particle interactions leading to particle trapping is demonstrated for inhomogeneous plasma. Qualitative comparison studies between initial value perturbation and driven problem is presented, which examines the relative difference in energy transfer time between the interacting modes. Effect of variation in background ion inhomogeneity amplitude as well as ion inhomogeneity scale length on the driven EPWs is reported.

Non-uniform electron density estimation based on electromagnetic wave attenuation in plasma

Abstract The surface of a high-speed vehicle reentering the atmosphere is surrounded by plasma sheath. Due to the influence of the inhomogeneous flow field around the vehicle, understanding the electromagnetic properties of the plasma sheath can be challenging. Obtaining the electron density of the plasma sheath is crucial for understanding and achieving plasma stealth of vehicles. In this work, the relationship between electromagnetic wave attenuation and electron density is deduced theoretically. The attenuation distribution along the propagation path is found to be proportional to the integral of the plasma electron density. This result is used to predict the electron density profile. Furthermore, the average electron density is obtained using a back-propagation neural network algorithm. Finally, the spatial distribution of the electron density can be determined from the average electron density and the normalized derivative of attenuation with respect to the propagation depth. Compared to traditional probe measurement methods, the proposed approach not only improves efficiency but also preserves the integrity of the plasma environment.

Growth of stimulated Raman instability by a density-modulated electron beam in laser-plasma interactions

A way to enhance the growth of stimulated Raman instability in laser-plasma interactions was investigated. This relies on the application of density modulation of a co-propagating electron beam in plasmas. In the stimulated Raman scattering process, an electromagnetic pump wave decays into a low-frequency wave and a scattered electromagnetic sideband wave. In this process, the pump wave produces an oscillatory velocity associated with the plasma electrons and the beam electrons. These oscillatory velocities combine with the existing low-frequency mode, producing ponderomotive force that drives high-frequency sideband waves. The sidebands couple to the pump wave, driving the beam-mode. A modulation of the electron beam density enhances the growth rate of the instability. The theoretical calculations show about 40% enhancements in growth of Raman instability at resonance (where the electron beam density modulation parameter approaches to unity) for the plasma density of the order of 1018 cm−3.

Thermal Conductivity and Thermal Hall Effect in Dense Electron-Ion Plasma

In this study, we examine thermal conductivity and the thermal Hall effect in electron-ion plasmas relevant to hot neutron stars, white dwarfs, and binary neutron star mergers, focusing on densities found in the outer crusts of neutron stars and the interiors of white dwarfs. We consider plasma consisting of single species of ions, which could be either iron [56]Fe or carbon [12]C nuclei. The temperature range explored is from the melting temperature of the solid T∼109 K up to 1011 K. This covers both degenerate and non-degenerate electron regimes. We find that thermal conductivity increases with density and temperature for which we provide analytical scaling relations valid in different regimes. The impact of magnetic fields on thermal conductivity is also analyzed, showing anisotropy in low-density regions and the presence of the thermal Hall effect characterized by the Righi–Leduc coefficient. The transition froma degenerate to non-degenerate regime is characterized by a minimum ratio of thermal conductivity to temperature, which is analogous to the minimum observed already in the case of electrical conductivity. We provide also formulas fit to our numerical results, which can be used in dissipative magneto-hydrodynamics simulations of warm compact stars.

Automatically Detected CSES Ionospheric Precursors Before Part of the Strong Aftershocks of the 23 January 2024 Wushi MS 7.1 Earthquake in Northwest China

Earthquake prediction is still a large challenge worldwide so far. In this paper, an automatic detection method was put into service immediately after the Wushi MS 7.1 earthquake on 23 January 2024 to weekly detect possible CSES (China Seismo-Electromagnetic Satellite) precursory information before impending aftershocks. An electron perturbation with an enhanced magnitude of 38.3% was first detected on 24 January 2024 at night orbit 33175 and the corresponding variations in different plasma parameters measured at this orbit presented a typical feature of electron depletion or plasma bubble with an abrupt decrease and then an increase after one minute. The Kp index was also checked during this period and the values reached 3.7 once on 23 and 24 January, which indicates that these ionospheric variations probably originated from solar activities instead of three strong aftershocks with a magnitude more than five in the following three days. However, uncertainties still exist. Then, an electron perturbation with amplitude of 24.6%, as well as an O+ one of 27.3%, was successfully searched automatically at the same revisiting orbit 33251 on 3 February 2024 in a magnetically quiet period. These two plasma variations, as well as ones of other ionospheric parameters, were characterized by highly synchronous properties, which increase the availability as seismic precursors. However, no obvious variations were observed at other revisiting orbits or other orbits near the aftershock areas during this period. An aftershock with magnitude of MS 5.3 and the strongest one of MS 5.8 took place on 24 and 25 February, respectively, 20 days after and 1000 km away.

Influence of species kinetics on discharge characteristics in oxygen helicon plasma

Abstract Oxygen (O2) helicon plasmas in multiple wave modes were excited by a right-helical antenna with an upper metal endplate at low pressure. Mode transitions were observed at increasing input power or magnetic field, characterized by obvious jumps of plasma parameters. Blue Core appears at high magnetic fields (~700 G) and input powers (~1700 W), with a large radial gradient of plasma density, ion line intensity, and electron temperature. Emission spectra demonstrate that the blue lights originate from O II lines. We found that the intensity ratio of O II to O I of Blue Core in O2 is lower by one order than that in N2 or Ar despite their similar ionization rates and plasma densities in Blue Core area. A high-temperature B-dot probe together with a waveform fitting procedure was used to present the measured oscillating waveforms of m =+1 helicon waves, showing distinct wave structures of different eigenmodes. Cavity mode resonance is suggested to be responsible for the formation of standing waves of discrete eigenmodes. A pressure balance model was developed to estimate the species densities around the central area in different modes, showing massive dissociation of O2 molecules and high density of O atoms locally, so that O2 helicon plasma behaves a species feature of monatomic gas discharge. The obviously low intensity of O II lines compared to O I lines of Blue Core in O2 is related to the quite high excitation threshold of O+ ions (~30 eV) although electron density and temperature are relatively high. The combined effects of dispersed reaction energy distribution, massive molecule dissociation and negative ion creation are considered to be the main causes for requirement of much higher RF power and magnetic field for Blue Core formation in O2 helicon plasma than that in Ar. The calculated radial profile of power deposition and the captured plasma morphology confirm that the dominant central electron heating is the essential reason for the large radial gradients of plasma density and electron temperature which contributes to the serious neutral depletion and Blue Core formation.

Analysis of uncertainty in measurement of electron temperature in low-pressure inductively coupled plasmas using microwave cutoff probe

Abstract In this study, we performed electron temperature measurements by using a square cutoff probe. Further, the measurement uncertainty was comprehensively analysed. The square cutoff probe allows for the measurement of the electron temperature based on the measured electron series resonance frequency and that of the electron plasma frequency based on the transmission spectrum of the plasma. The electron temperatures were determined under varying gas pressures and input power conditions, and the results were compared with those obtained using a single Langmuir probe. Also, the impact of electron-neutral collision frequency on electron temperature measurement using square cutoff probe was analyzed based on a plasma equivalent circuit model. The square cutoff probe is expected to serve as a valuable diagnostic tool for the precise characterisation of electron temperature, offering localised, accurate, and easily interpretable features.

CONCERNING EFFECTS OF INERT CARRIER GAS ON DENSITIES OF ACTIVE SPECIES AND ZrO2 ETCHING KINETICS IN CHLORINE PLASMA

In this work, we investigated the influence of inert carrier gas on electro-physical plasma parameters, steady-state densities of active species and kinetics of their interaction with ZrO2 under the condition of “soft” reactive-ion etching in chlorine. This regime assumes the lower-than-usual negative bias voltage in order to reduce both ion bombardment energy and etched surface damage. The combination of plasma diagnostics by Langmuir probes and 0-dimensional plasma modeling allowed one to analyze formation and decay kinetics for neutral and charged species at various gas mixing ratios. It was found that the mixing of Cl2 with Ar or He at constant total gas pressure a) causes an increase in both electron temperature and plasma density; b) increases the Cl2 dissociation degree through the acceleration of electron-impact processes; and c) intensifies the ion bombardment by the change of ion flux. From etching experiments, it was found also that the ZrO2 etching rate is mostly composed by its chemical component, but does not correlate with the change in the Cl atom flux. The latter reveals that a) the dominant ZrO2 etching mechanism is the ion-assisted chemical reaction and b) an increase in the effective reaction probability toward Ar or He rich plasmas reflects the acceleration of ion-induced heterogeneous effects, such as the destruction of Zr-O bonds and/or the desorption of low-volatile ZrClx compounds. The lower neutral/charged ratio obtained in Ar-containing plasma allows one to assume the more anisotropic etching. It was shown that above findings are surely valid in the pressure range of 4–12 mTorr as well at bias powers of 100 – 300 W. For citation: Efremov A.M., Smirnov S.A., Betelin V.B., Kwon K.-H. Concerning effects of inert carrier gas on densities of active species and ZrO2 etching kinetics in chlorine plasma. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 11. P. 40-54. DOI: 10.6060/ivkkt.20246711.7073.

Second Harmonic Generation of High Power Cosh-Gaussian Beam in Thermal Quantum Plasma: Effect of Relativistic and Ponderomotive Nonlinearity

Second harmonic generation (SHG) of high power Cosh-Gaussian(ChG) beam in thermal quantum plasma (TQP) is explored in current investigation. Relativistic and ponderomotive nonlinearities are taken together in present investigation. Combination of relativistic-ponderomotive nonlinearities causes modification in electron mass, thereby producing density gradients inside plasma. This further produces self-focusing of main beam. The well-known WKB and paraxial approaches are used for solving main beam’s wave equation and to obtain 2nd order ordinary differential equation (ODE). There is generation of electron plasma wave (EPW) due to these density gradients. Excited EPW interacts with main beam to generate 2nd harmonics in plasma. Effects of combined relativistic-ponderomotive nonlinearities and established laser - plasma parameters on beam’s waist and SHG yield are studied in present study.

Impact of High-Power Cosh-Gaussian Beam on Second Harmonic Generation in Collisionless Magnetoplasma

The impact of high power Cosh-Gaussian (ChG) beam on Second harmonic generation (SHG) in Collisionless magnetoplasma is explored in present work. Whenever the input beam propagates along external magnetic magnetic field direction, then there are two propagation modes viz. extraordinary mode and ordinary mode. The modification in magnetic field strength causes redistribution of carriers. The density gradients get established in plasma in a normal direction to input wave due to ponderomotive force. Further, there is production of electron plasma wave (EPW) at input wave frequency due to density gradients. EPW nonlinearly interacts with pump wave causing generation of 2nd harmonics. The 2nd order differential equation (ODE) for beam width of and efficiency of 2nd harmonics are derived through well-known paraxial theory approach. RK4 method is employed for carrying out numerical calculation of nonlinear ODE along with efficiency of 2nd harmonics. Impact of change in selective laserplasma parameters and externally applied magnetic field on beam waist of input wave and efficiency of SHG are also explored.

Characterization of optical depth for laser produced plasma extreme ultraviolet source

This study investigates the emission mechanism of laser-produced plasma extreme ultraviolet source (LPP-EUV). In the experiment, the EUV radiation is generated by a 1064 nm laser interacting with slab Sn target. The EUV emission is characterized by EUV energy monitors and an EUV spectrometer. The dependency of CE on laser intensity and plasma relative optical depth is explored by a plasma emission-absorption layer model. The dependency is confirmed by an optical interferometry measurement of plasma electron density for the first time. Our work provides a method for characterizing and optimizing the optical depth of laser driven EUV source.

Measurement of plasma electron energy distribution functions by Langmuir probe using a modified AC modulation method

Abstract In the diagnosis of vacuum discharge plasma using the Langmuir probe, the electron energy distribution function (EEDF) is closely related to the second derivative of current to voltage (d 2 I/dV 2) on the Langmuir probe. While d 2 I/dV 2 is very sensitive to probe noise, its accuracy directly affects the measurement results of the EEDF. In this paper, a modified AC modulation method is proposed to improve the measurement accuracy of the EEDF. First, two small AC signals of different amplitudes are modulated on the measured DC scanning voltage of the Langmuir probe, and the probe current signal is measured. Then, the fundamental amplitudes of the two AC signals are corrected by spectral analysis and using the all-phase fast Fourier transformation—fast Fourier transformation amplitude correction algorithm. Then the accurate first-order derivative of the probe current to voltage (dI/dV) is obtained using the AC modulation derivative correction algorithm, and finally the EEDF is obtained by numerically differentiating dI/dV to obtain d 2 I/dV 2. The method of this paper is compared with the traditional data processing method through experiments, and the results show the superiority and effectiveness of the method.