Maximum Electron Density Research Articles

Ripple period adjustment on SiC surface based on electron dynamics control and its polarization anisotropy

In this paper, the Mach Zehnder interferometer is utilized to generate a collinear dual optical path with 800-nm center wavelength, 1 kHz repetition rate, 120-fs pulse duration and an energy ratio of 1:1 to scan 6H-SiC crystal at a scanning speed of 500 μm/s, resulting in laser-induced periodic surface structure (LIPSS). From the perspective of instantaneous electron density level, variation of the period of low spatial frequency LIPSS (LSFL) with interpulse delay time and polarization angle is studied. The scanning electron microscope (SEM) characterization of the line-scanned ablation zone combined with fast Fourier transformation (FFT) spectrum analysis shows that the period of LSFL decreases with the increase of delay time, and remains stable when the delay exceeds 240 fs. Meanwhile, the period of LSFL increases with the increase of polarization angle under the same delay time, showing an anisotropy that dependent on the polarization angle. The variation trend of the maximum electron density level with delay time calculated by electron rate equation is roughly consistent with the periodic variation trend. Interaction between incident light and transient metal-like SiC surface is simulated based on finite-difference time-domain method (FDTD). The simulation results show that the surface of the sample has a periodic light field enhancement structure controlled by the transient electron density, which explains the phenomenon that the period decreases with increasing delay time. It is further confirmed that the formation of LSFL is due to the interference of incident light and surface plasmon, and the period of LSFL can be controlled by adjusting the electron density level by delay time. The periodic polarization dependence of LSFL may be related to the relative orientation change of the laser pulse front tilt (PFT) and laser polarization.

염류용액 방전의 구동 특성에 관한 연구

In this study, the change in the characteristics of the saline solution discharge were investigated with the variation of driving condition. Regardless of the pulse polarity to the pin electrode, the amplitude of circuit current decreased but flew continuously with the insertion of series resistor to the power source when 5% duty ratio pulse was applied to a saline solution of 0.9% mass per unit volume in a pin to plate structure. The temperature of the discharge medium was measured from the spectrum of the hydroxy group molecular lines near 308 [nm] obtained during discharge, and the electron density using the Stark broadening of the Hβ line at 486 [nm], which is one of Balmer series hydrogen atomic line. The maximum temperature and electron density in the discharge medium decresed with the increase of series resistor inserted when the negative pulse was applied to the pin electrode. On the other hand, the positive pulse application to the pin electrode hardly led a temperature change while the change in the electron density was observed. It is estimated that the negative pulse application to a pin electrode and series resistor insertion in the driving circuit will helpful to widening the operation window in a liquid discharge.

On the Altitude Patterns of Photo‐Chemical‐Equilibrium in the Martian Ionosphere: A Special Role for Electron Temperature

AbstractThe ionosphere at Mars is governed by photo‐chemical‐equilibrium (PCE) at and below the height of maximum electron density (∼130 km), while the topside ionosphere blends PCE with other processes (e.g., plasma dynamics). We studied the altitude profile from 135 to 260 km where PCE conditions transition to the non‐PCE domain. Using MAVEN observations of electron density (Ne) and temperature (Te), CO2 densities, and integrated energy flux Fsun(5–93 nm), we tested the PCE relationship (Mendillo et al., 2017, https://doi.org/10.1002/2017ja024366). We found high correlations coefficients (CC = 80–90%) for heights 25–40 km above hmax, and then decreases to CC = 50% (defining partial PCE control). Surprisingly, CCs returned to > 50% in the 160–175 height range. We found the re‐establishment of PCE control occurs where the Te values rise sharply and thereby reduce the plasma recombination rate due to its inverse dependence on electron temperature. Enhancements in the topside ionosphere due to that process were first postulated by Fox and Yeager (2006, https://doi.org/10.1029/2006JA011697) to explain the “shoulder” seen Ne(h) profiles from radio occultation experiments. MAVEN data now provide the first comprehensive set of in situ observations to relate this enigmatic “bulge” to observed PCE parameters. Moreover, MAVEN observations reveal that additional sources are present to account for the Ne enhancements larger than possible from the thermal process alone.

Isotopic analysis and plasma diagnostics for lithium detection using combined laser ablation–tuneable diode laser absorption spectroscopy and laser-induced breakdown spectroscopy

Laser-Induced Breakdown Spectroscopy (LIBS) enables rapid stand-off measurements of potentially hazardous material which is particularly favourable for applications in the nuclear industry. Isotopic characterisation with LIBS remains challenging because of the narrow separation of isotopic emission lines, which demands large, high resolution spectrometers. To address this, laser ablation (LA)-Tuneable Diode Laser Absorption Spectroscopy (TDLAS) has been combined with LIBS to analyse laser-produced plasma of lithium. Isotope ratio calculations were performed by fitting multiple peaks to the Li absorption spectra, achieving a relative error of 13% at later delay times after line broadening had reduced. Double-pulsed laser ablation resulted in narrower absorption peaks but more noise in the absorption spectra. LIBS and LA-TDLAS spectra were used simultaneously to calculate plasma temperature and electron density for both single- and double-pulsed laser ablation. The Doppler broadening of absorption peaks from LA-TDLAS was used to calculate the plasma temperature after long time delays of 200 μs and the temperature followed an exponential decay which was extrapolated back to early delay times in order to predict the temperature throughout the plasma lifecycle. The electron density was calculated using the Stark broadening of emission peaks from the LIBS spectra, which were temperature-corrected by accounting for the Doppler broadening. Both single- and double-pulsed-laser ablation plasmas exhibited maximum electron densities of around 1016 to 1017 cm−3, although the decay rate was reduced by around a factor of 2 using DP-laser ablation. We have shown that the combination of emission and absorption spectroscopy with LIBS and LA-TDLAS is useful for isotopic analysis and calculating laser ablation plasma properties. We have demonstrated that double pulsed laser ablation has the potential to enable more isotopic pairs to be analysed due to the narrower absorption linewidth.

Attenuation properties of EM wave by magnetized nonuniform plasma slab coated on perfect conductor plane

AbstractThe total amplitude reflection coefficient of EM wave in a nonuniform plasma slab coated on perfect conductor plane is newly derived by using the scattering matrix method (SMM), and the attenuation is calculated. Three types of plasma electron density profile, that is the hyperbolic, sinusoidal, and linear profiles, are used. The external magnetic field and plasma parameters such as the maximum electron density and collision frequencies are discussed to calculate the attenuation of EM wave. The calculation results show that the plasma electron density profile and maximum electron density exert a large effect to the attenuation of EM wave and the attenuation under the uniform external magnetic field is taken place by the electron cyclotron resonance absorption, the up hybrid resonance absorption and geometric resonances absorption.

Observations of precipitation energies during different types of pulsating aurora

Abstract. Pulsating aurora (PsA) is a diffuse type of aurora with different structures switching on and off with a period of a few seconds. It is often associated with energetic electron precipitation (>10 keV) resulting in the interaction between magnetospheric electrons and electromagnetic waves in the magnetosphere. Recent studies categorize pulsating aurora into three different types – amorphous pulsating aurora (APA), patchy pulsating aurora (PPA), and patchy aurora (PA) – based on the spatial extent of pulsations and structural stability. Differences in precipitation energies of electrons associated with these types of pulsating aurora have been suggested. In this study, we further examine these three types of pulsating aurora using electron density measurements from the European Incoherent Scatter (EISCAT) VHF/UHF radar experiments and Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA) cosmic noise absorption (CNA) measurements. Based on ground-based all-sky camera images over the Fennoscandian region, we identified a total of 92 PsA events in the years between 2010 and 2020 with simultaneous EISCAT experiments. Among these events, 39, 35, and 18 were APA, PPA, and PA types with a collective duration of 58, 43, and 21 h, respectively. We found that, below 100 km, electron density enhancements during PPAs and PAs are significantly higher than during APA. However, there are no appreciable electron density differences between PPA and APA above 100 km, while PA showed weaker ionization. The altitude of the maximum electron density also showed considerable differences among the three types, centered around 110, 105, and 105 km for APA, PPA, and PA, respectively. The KAIRA CNA values also showed higher values on average during PPA (0.33 dB) compared to PA (0.23 dB) and especially APA (0.17 dB). In general, this suggests that the precipitating electrons responsible for APA have a lower energy range compared to PPA and PA types. Among the three categories, the magnitude of the maximum electron density shows higher values at lower altitudes and in the late magnetic local time (MLT) sector (after 5 MLT) during PPA than during PA or APA. We also found significant ionization down to 70 km during PPA and PA, which corresponds to ∼200 keV of precipitating electrons.

Experimental and simulation analysis of dielectric barrier discharge based pulsed cold atmospheric pressure plasma jet

In this paper, experimental and simulation investigations have been carried out for the characterization of the dielectric barrier discharge based cold atmospheric pressure plasma jet (C-APPJ) for a unique geometry in which argon gas is used at different flow rates along with pulsed DC supply at different frequencies. A tapered structure has been fabricated for acquiring sufficient velocity of the gas at a low flow rate. The typical V–I characteristic of the C-APPJ has been presented for a wide range of flow rates (1–5 SLM) and frequencies (10–25 kHz). On increasing the gas flow rate and frequency, discharge sustains for the lower potential of 5 kV and requires low power. It has been observed that the power dissipation for the formation of the plasma jet increases on increasing frequency at a constant flow rate. Also, the analysis of discharge current is presented for each combination of the flow rate and operating frequencies. Furthermore, the investigation has been carried out for the analysis of electron density, velocity distribution of gas, and distribution of the electric field in the C-APPJ for the same experimental geometry through the simulation tool COMSOL Multiphysics. The maximum electric field of 3.22×106 V/m and the maximum electron density of 3.38×1019 1/m3 have been observed during the propagation of the plasma jet at 1 SLM flow rate. Such qualitative analysis of jet formation along the electric field distribution in a wide range of operating parameters would certainly be helpful in the development of dielectric barrier discharge based C-APPJ sources suitable for the biomedical and food related applications.

Spectroscopic plasma diagnosis of V2O5 at a Variable of Operating Power and Pressure With Radio Frequency Magnetron Sputtering

In this paper, we investigate the basic characteristics of “magnetron sputtering plasma” using the target V2O5. The “magnetron sputtering plasma” is produced using “radio frequency (RF)” power supply and Argon gas. The intensity of the light emission from atoms and radicals in the plasma measured by using “optical emission spectrophotometer”, and the appeared peaks in all patterns match the standard lines from NIST database and employed are to estimate the plasma parameters, of computes electron temperature and the electron density. The characteristics of V2O5 sputtering plasma at multiple discharge provisos are studied at the “radio frequency” (RF) power ranging from 75 - 150 Watt and gas pressure (0.1, 0.08) mbar. One can observe that the intensity of the emission lines increases with increasing the sputtering power. We find that the electron temperature excess drastically from 0.95 eV to 1.11eV when the emptying gas pressure excess of 0.1 to 0.08 mbar. On the other hand the excess electron temperature from 0.9 to 1.01 eV with increasing sputtering power from 100 to 125 Watt, while the electron density decrease from 5.9×1014 to 4.5×1014 cm−3 with increasing sputtering power. and electron density decrease with increasing of pressure from 4.25×1014 to 2.80×1014 cm−3, But the electron density maximum values 5.9×1014 at pressure 0.08 mbar.

Ionospheric Response at Conjugate Locations During the 7–8 September 2017 Geomagnetic Storm Over the Europe‐African Longitude Sector

AbstractThis paper focuses on unique aspects of the ionospheric response at conjugate locations over Europe and South Africa during the 7–8 September 2017 geomagnetic storm including the role of the bottomside and topside ionosphere and plasmasphere in influencing electron density changes. Analysis of total electron content (TEC) on 7 September 2017 shows that for a pair of geomagnetically conjugate locations, positive storm effect was observed reaching about 65% when benchmarked on the monthly median TEC variability in the Northern Hemisphere, while the Southern Hemisphere remained within the quiet time variability threshold of ±40%. Over the investigated locations, the Southern Hemisphere midlatitudes showed positive TEC deviations that were in most cases twice the comparative response level in the Northern Hemisphere on the 8 September 2017. During the storm main phase on 8 September 2017, we have obtained an interesting result of ionosonde maximum electron density of the F2 layer and TEC derived from Global Navigation Satellite System (GNSS) observations showing different ionospheric responses over the same midlatitude location in the Northern Hemisphere. In situ electron density measurements from SWARM satellite aided by bottomside ionosonde‐derived TEC up to the maximum height of the F2 layer (hmF2) revealed that the bottomside and topside ionosphere as well as plasmasphere electron content contributions to overall GNSS‐derived TEC were different in both hemispheres especially for 8 September 2017 during the storm main phase. The differences in hemispheric response at conjugate locations and on a regional scale have been explained in terms of seasonal influence on the background electron density coupled with the presence of large‐scale traveling ionospheric disturbances and low‐latitude‐associated processes. The major highlight of this study is the simultaneous confirmation of most of the previously observed features and their underlying physical mechanisms during geomagnetic storms through a multi–data set examination of hemispheric differences.

Ultrafast pump-probe microscopic imaging of femtosecond laser-induced melting and ablation in single-crystalline silicon carbide

The temporal and spatial evolution of femtosecond laser-induced phase transitions and ablation on single-crystalline silicon carbide (SiC) were investigated via pump-probe microscopy in air on a time scale from approximately 100 fs to 1 ns. The largest reflectivity change was observed between 300 fs and 1 ps after excitation, which is due to free carrier generation, and the Drude model calculations indicated that the maximum free electron density was greater than 3.3 × 1021 cm−3. After a few picoseconds, there was direct evidence of the production of a rarefaction wave propagating towards the bulk, whose propagation velocity was estimated to be 3286 m/s. At delay times between a few hundreds of picoseconds and 1 ns, characteristic transient ring patterns were clearly observed and were related to the optical interference of the probe laser pulse reflected at the front surface of the ablating layer and at the interface of the non-ablating substrate. The estimated expansion velocity of the ablation front in 6H–SiC was found to be comparable to or slower than those reported for other semiconductors and dielectrics.

Dual-Wavelength Interferometric Measurement of Electrically Exploded Aluminum and Copper Wires in Low-Pressure Air for Electron and Ion Density Calculation

Electron and atomic densities of Cu and Al plasmas in low-pressure air are studied using the recently reported dual-wavelength (1064 and 532 nm) interferometric diagnostic. The electrical explosion of a 99.999% pure, straight wire forms cylindrical plasma volumes within a low-pressure air chamber, and the probing lasers' interferometry patterns are simultaneously recorded at prescribed times after wire explosion. The measurements are performed repeatedly from 50 to 1200 ns in 50-ns increments allowing the calculation of electron and ion densities and the observation of the plasma's expansion and dissipation. The densities are calculated from fringe line analysis using a signal-processing-based algorithm that automatically extracts the fringe ratio. Finally, the maximum average volumetric electron and ion densities are calculated. The results of atomic density agree with past reports but are two orders greater than electron density, which suggests that full ionization is unattained.

Observations and Electron Density Retrievals of Jupiter's Discrete Auroral Arcs Using the Juno Microwave Radiometer

AbstractJupiter's aurorae reflect microwave radiation emitted upward from Jupiter's atmosphere and downward from the cold sky above due to regions in the auroral plasma with increased electron densities. The lack of thermal radiation from the atmosphere was observed by Juno's Microwave Radiometer (MWR) on overflights of the aurorae during seven different orbits. Out of Juno's first 21 orbits, seven orbits inferred enhanced electron densities in Jupiter's auroral arcs. The most profound disruption in microwave emission was observed during Perijove 5. This perijove demonstrated the most significant cold spot for Channel 1 (0.6 GHz), with cold spots also present in Channels 2 (1.25 GHz) and 3 (2.6 GHz) in a location where the influence of Jupiter's moon, Io, likely increased the electron density in Jupiter's aurora. The maximum electron densities retrieved from Channel 1 are on the order of 3 × 109 cm−3, and in the presence of the Io flux tube, electron densities could reach 1010 cm−3 affecting Channels 2 and 3.

Plasma characteristics of a tapered coaxial gun and its damage effect on tungsten target

• A tapered coaxial plasma gun with negative pulse was used to obtain more suitable plasma parameters for simulation of the Type- I ELM in tokamak. • The plasma parameters of the tapered coaxial gun were measured. The characteristics of plasma are analyzed. • Fusion plasma surface interactions relevant results were provided. Damage effect on target was analyzed. Due to the property of high energy density, temperature and density, the plasma prodced by the coaxial gun is usually untilized to simulate the Type- I ELM in tokamak. In this work, the plasma characteristics of a tapered coaxial gun was studied and its effect on the tungsten target was investigated. By using current probe, photodetector, spectrometer and calorimeter, it is found that the plasma energy density, density and velocity increase obviously with the discharge voltage. The maximum energy density could reach 1.4 MJ/m 2 , the maximum electron density could reach 3 × 10 15 /cm 3 , and the maximum ion kinetic energy could reach 113 eV at the voltage of 16 kV, which is suitable for simulating the type I Elms in Tokamak. After one shot, there are many cracks and ablative spots on the surface of W target. Whose size could reach ∼ μm by scanning electron microscope(SEM), this is because W material will become brittle after the frequent heating and cooling alternations under thermal shock and the melt motion driven by high plasma pressure gradient. With the Energy Dispersive Spectrometer(EDS), it can be seen that no matter from the cracks and other area of the surface after one shot, the impurity can be ignored. These results help us to better understand the damage effect of tungsten target for further research.

Controlling of surface ablation threshold of fused silica by double-pulsed femtosecond laser

Femtosecond laser (fs) ablation is an effective method to processing waveguide, microfluidic channel and other functional devices in fused silica glass. The accuracy of ablation is critical for high-performance devices. In this paper, a double-pulse femtosecond laser was used to control the surface ablation threshold of fused silica. It was found that, when the delay time of the double pulses ranged from 0 to 100 ps, with the increasing of delay time, the ablation threshold first rapidly increased to the maximum value, then fell to a stable value. And the overall threshold was higher than the threshold at 0 ps, which means the processing accuracy could be significantly improved. By simulating the relationship between the maximum electron density of conduction band and the time delay, it can conclude that the modification of threshold was caused by the difference of maximum electron density. In addition, to find the more optimized processing parameters, we also studied the weights of the two sub-pulses at 10 ps. These results provide an important reference for ultra-precision machining.

Submicrosecond Spectroscopy of Lightning-Like Discharges: Exploring New Time Regimes.

Submicrosecond (0.476 s per frame with an exposure time of 160 ns) high‐resolution (0.38 nm) time‐resolved spectra of laboratory‐produced lightning‐like electrical discharges have been recorded for the first time within the visible spectral range (645–665 nm). The spectra were recorded with the GrAnada LIghtning Ultrafast Spectrograph (GALIUS), a high‐speed imaging spectrograph recently developed for lightning research in the IAA‐CSIC. Unprecedented spectral time dynamics are explored for meter long laboratory electrical discharges produced with a 2.0 MV Marx generator. The maximum electron density and gas temperature measured in a timescale of 0.50 s (160 ns) were, respectively, 10 cm and 32,000 K. Overpressure in the lightning‐like plasma channel, black‐body dynamics, and self‐absorption in spectral lines were investigated.

Ionospheric and Magnetic Signatures of a Space Weather Event on 25–29 August 2018: CME and HSSWs

AbstractWe present a study concerning a space weather event on 25–29 August 2018, accounting for its ionospheric and magnetic signatures at low latitudes and midlatitudes. The effects of a storm in several longitudinal sectors (Asia, Africa, America, and the Pacific) have been analyzed using various parameters such as total electron content (TEC), geomagnetic field, and column [O/N2] ratio. Positive ionospheric storms are found in all the longitudinal sectors having its maximum effects in the Asian sector, whereas the negative ionospheric storms have been observed in the summer hemisphere (Northern Hemisphere). A large decrease in [O/N2] ratio in the Northern Hemisphere is a possible cause of the observed negative storm effects. Ionospheric F2 region maximum electron density (NmF2) and TEC have shown a positive correlation during this storm. The study suggests that storm time‐generated wind does not have a uniform planetary extension and mainly affects dayside (America and Pacific) and duskside (Africa) sectors. During the space weather event, we observe an asymmetric variation of the magnetic field as a function of the longitude. On the other hand, the magnetic variations at midlatitudes are found to be symmetric in both hemispheres. A signature of the disturbance dynamo (anti‐Sq circulation) has been observed, mainly at low latitudes. We emphasize that the partial ring current (PRC), estimated by the ASYM‐H magnetic index, must also be taken into account along with the SYM‐H index for a better approximation of ionospheric currents. The study further suggests existence of several electric current cells in the ionosphere, which is consistent with the Blanc‐Richmond model.

A simulation study of argon discharge in PIG ion source with axial magnetic field

In this study, we used a two-dimensional fluid model to investigate the argon discharge in Penning ion gauge (PIG) ion source influenced by magnetic field and the structure of ion source. Under fixed anode voltage U and pressure P, the relationships between the axial magnetic field, the structure parameter K, which is the ratio of the distance of two cathodes and the diameter of the anode tube, and the electron density are obtained. For fixed magnetic field B=0.01 T and pressure P=0.5 Torr, the electron density along the central axis has the maximal value when K=0.8. With fixed K=0.8 and P=1 Torr, the maximal electron density was found when B=0.1 T. Our results imply that there are optimal values for magnetic field and K which induce the maximal plasma density.

Beam Plasma Characteristics of a Helicon Plasma Source Measured by a Spatially Resolved Optical Emission Spectroscope

Beam plasma directly forms the thrust of single-stage helicon plasma thrusters and its properties are the input parameters of the two-stage helicon thruster. Therefore, the spatial distribution of the beam plasma is vital for both single-stage and two-stage helicon thrusters. Using an optical emission spectroscope with a radial resolution of 5 mm, the spatial distribution of the beam plasma parameters and its variation with different input radio frequency (RF) powers (100–1000 W) and diameters of the discharge tube (20–60 mm) was investigated. Results show that the electron density decreases with both axial and radial distances, but the electron temperature remains nearly constant. The electron density increases with increasing input RF powers because of an increase of power deposition when the electron temperature remains constant. The radial profiles of electron density are flat, and the maximum electron densities located in the center line decrease with increasing diameters of the discharge tube, which is due to the decrease in the power density.

Investigation of laser-induced plasma in SF6 at different pressures using Thomson scattering

Thomson scattering was applied to measure the electron density and temperature in laser-induced SF6 plasmas at various pressures (0.2–2 atm). The plasma was induced by the Nd:YAG laser (1064 nm, 200 mJ, and 7 ns) focused into a chamber filled with SF6. A second harmonic Nd:YAG laser (532 nm, 50 mJ, and 6 ns) was used to probe the distributions of electron density and temperature. The images after breakdown indicate that higher pressure accelerates the plasma evolution and enhances the asymmetry of the plasma structure. Additionally, different from toroidal structures in other gases, a special vortex structure appeared in SF6. The electron density around the axis at 0.2 atm decreases from 1.66×1023 m−3 at 2 μs to 4.50×1022 m−3 at 6 μs, and meanwhile, the electron temperature drops from 22 050 K to 15 600 K. At 2 atm, from 2 μs to 6 μs, the electron density decreases from 3.00×1023 m−3 to 5.23×1022 m−3 and the temperature drops from 44 000 K to 14 800 K. The time exponent obtained by fitting the maximum electron density using the power law decreases from −1.206 to −1.669 in the pressure range from 0.2 atm to 2 atm, indicating that the pressure increases the decaying rate of electron density. From 0.4 atm to 2 atm, the time exponent of the decay of electron temperature decreases from −0.499 to −0.926. The comparisons among laser-induced plasmas in various gases show that the decaying rates of both electron density and temperature in SF6 are superior to air and argon.

Investigation of global ionospheric response of the severe geomagnetic storm on June 22-23, 2015 by GNSS-based TEC observations

The magnetosphere and ionosphere have a crucial interaction during severe geomagnetic storms. The Global Navigation Satellite System (GNSS) provides high-quality ionospheric observations with high temporal and spatial resolution, is generally preferred to investigate the ionospheric variation. In this study, the storm-time ionospheric response of the June 2015 severe storm (Dstmin = −208 nT) was investigated by the Total Electron Content (TEC) data of the Global Ionosphere Maps (GIMs), COSMIC radio occultation (RO) and a chain of International GNSS Service (IGS) stations. GIMs were used to show the global TEC variation during the storm. COSMIC RO data were also utilized to investigate the TEC variation and electron density profiles in an anomaly area with a limited time interval. GNSS TEC data of the 16 IGS stations were utilized to investigate the ionospheric variability on different latitudes of hemispheres. The results showed that intense positive phases formed in high latitudes of the Southern Hemisphere (SH) and the western longitudes of the Northern Hemisphere (NH), especially over the North Atlantic Ocean until the main phase of the storm. Besides, negative phases were observed in high latitudes and eastern longitudes of the NH. During the recovery phase of the storm, positive phases were seen in the low latitudes of the SH and the ionospheric conditions calmed down in the entire SH after the depletion of these phases. Negative phases were also observed almost wholly covered in the NH, which denser in the European-African sector. As a particular result, the electron density profiles of COSMIC RO showed that the ionospheric phases of the June 2015 storm not only related to TEC values but also the altitude of maximum electron density.