Axial Magnetic Field Strength Research Articles

Modeling and optimization of a relativistic magnetron with transparent cathode and output mode

Abstract This paper outlines the results of particle-in-cell simulations of a relativistic magnetron with six cavities and a transparent cathode configuration. Excitation of the π mode in the interaction region was attained, which in turn led to $\textrm{TE}_{11}$ mode emission of microwaves to the waveguide. This mode transformation was achieved with a non-symmetric diffraction output, consisting of four large and two small tapered cavities. Simulations were performed with a voltage across the anode-cathode gap varying from 164 to 356 kV, and axial magnetic field strengths between 0.24 and 0.34 T. Maximum efficiency of 37% was obtained with a peak output power of 590 MW, having a voltage of 261 kV and a magnetic field of 0.30 T. Furthermore, a frequency of 2.57 GHz and a rise time of microwaves at the waveguide of 15 ns were demonstrated. The electron leakage current was shown to decrease from ∼10 $\%$ to less than $1\%$ when employing a longer interaction region, while still exhibiting good performance. Additionally, we show that there is an optimal range of voltages given a magnetic field, for which π mode excitation with high efficiency is attained.

Chaotic dynamics in X-ray free-electron lasers with an optical undulator.

In this work, the chaotic motions of relativistic electrons in X-ray free-electron lasers are investigated using an optical undulator in the presence of a magnetized ion-channel background. To miniaturize X-ray light sources, the optical undulator is a promising concept. The optical undulator provides higher optical gain than conventional magnetostatic undulators due to its micrometer wavelength. In addition, it reduces the required electron beam energy from several GeV to the multi-MeV range to produce X-ray pulses. The interaction of an optical undulator with an intense relativistic electron beam is a highly non-linear phenomenon that can lead to chaotic dynamics. At synchrotron radiation sources, the possibility of chaos control for X-ray FELs can be critical for certain classes of experimental studies. The equations of motion for a relativistic electron propagating through the optical undulator in the presence of a magnetized ion-channel can be derived from the Hamiltonian of the interaction region. Simulation results revealed that the intensity of the perturbation route from orderly behavior to chaos depends on the beam density, axial magnetic field strength, ion-channel density parameter, and pump laser undulator. Specific values of parameters were obtained for the transition from regular to chaotic paths. Bifurcation diagrams of the system were plotted to demonstrate the origin of chaos at a critical point, and Poincaré maps were created to distinguish between chaotic and orderly motions of electrons. The proposed new scheme can help to improve X-ray FELs, which have potential usages in basic sciences, medicine, and industry.

Laboratory study of the PFRC-2's initial plasma densification stages

Initial plasma densification by odd-parity rotating magnetic fields (RMFo) applied to the linear magnetized Princeton field-reversed configuration (PFRC-2) device with fill gases at pressures near 1 mTorr proceeds through two phases: a slow one, characterized by a rise time τslow∼100μs, followed by a fast one, characterized by τfast∼10μs. The transition from slow to fast occurs at a line-integral-averaged electron density, tne, near 2×1011 cm−3, independent of magnetic field. Over most of the range of experimental parameters investigated, as the PFRC-2 axial magnetic field strength was increased, RMFo power decreased, gas fill pressure lowered, or lower atomic mass unit (AMU) fill gas used, the duration of the slow phase lengthened from 50 μs to longer than 10 ms after the RMFo power began. The post-fast-phase maximum ne increases with the fill-gas AMU, exceeding 5 × 1013 cm−3 for Ar. The slow phase is consistent with atomic physics processes and field-parallel sound-speed losses. The fast phase may be explained by improved axial confinement, possibly augmented by radial or axial contraction of the plasma. Another possible explanation, a large increase in electron temperature, is inconsistent with x-ray emission. The ne behavior is discussed in relation to the E to H transition.

DC magnetic field-assisted improvement of textile dye degradation efficiency with multi-capillary air bubble discharge plasma jet.

Axial DC magnetic field-assisted multi-capillary underwater air bubble discharge plasma jet has been used to study the productions of reactive oxygen species. Analyses of optical emission data revealed that the rotational (Tr) and vibrational temperatures (Tv) of plasma species slightly increased with magnetic field strength. The electron temperature (Te) and density (ne) increased almost linearly with magnetic field strength. Te increased from 0.53 to 0.59eV, whereas ne increased from 1.03 × 1015cm-3 to 1.33 × 1015cm-3 for B = 0 to B = 374 mT, respectively. Analytical results from the plasma treated water provided that the electrical conductivity (EC), oxidative reduction potential (ORP), and the concentrations of O3 and H2 O2 enhanced from 155 to 229 µS cm-1, 141 to 17mV, 1.34 to 1.92mg L-1, and 5.61 to 10.92mg L-1 due to the influence of axial DC magnetic field, while [Formula: see text] reduced from 5.10 to 3.93 for 30min treatment of water with B = 0 and B = 374 mT, respectively. The model wastewater prepared with Remazol brilliant blue textile dye and the plasma treated wastewater studied by optical absorption spectrometer, Fourier transform infrared spectrometer, and gas chromatography mass spectrometer. The results show that the decolorization efficiency increased ~ 20% after 5min treatment for the maximum B = 374 mT with respect to zero-magnetic field and, power consumption, and electrical energy cost reduced ~ 6.3% and ~ 4.5%, respectively, due to the maximum assisted axial DC magnetic field strength of 374 mT.

Design and studying the effect of Polepiece shape on the magnetic and optical properties of the unipolar lens

The investigation of a study of each design included the calculation of its axial magnetic field the magnetization of the lens in addition to the magnetic flux density using Finite Element Method (FEM) at three different values of current density (σ = 2,4 and 6 A/mm2). So clearest values and behavior have been obtained at the value current density of (2 A/mm2). It is found that the best magnetizing properties, the highest value of magnetic flux and the lowest value of band width of the axial magnetic field strength have been obtained when the pole head shape length was of (1 mm). The effect of current density on the optical properties has been also studied, and it is found that optical properties have been improved also, and chromatic and spherical aberration values have been decreased significantly. Thus, lens was chosen as the best design among the proposed designs.

Design and Studying the Effect of Inner Bore Diameter of Unipolar Lens

This work investigated the development of magnetic and optical properties and the invention of a previously unused lens. Many new designs have been suggested for a unipolar magnetic lens based on changing the width of the inner bore and fixing the other geometrical parameters of the lens to improve the performance of unipolar magnetic lenses. The investigation of a study of each design included the calculation of its axial magnetic field the magnetization of the lens in addition to the magnetic flux density using Finite Element Method (FEM). it was found that the best magnetizing properties, the highest value of magnetic flux and the lowest value of band width of the axial magnetic field strength have been obtained when the width of the inner cavity was (55 mm). The effect of current density on the optical properties has been also studied, and it was found that the optical properties have been improved also, and the chromatic and spherical aberration values have decreased significantly. Thus, the lens (55 mm) was chosen as the best design among the proposed designs.

In situ multi-spacecraft and remote imaging observations of the first CME detected by Solar Orbiter and BepiColombo

Context.On 2020 April 19 a coronal mass ejection (CME) was detected in situ by Solar Orbiter at a heliocentric distance of about 0.8 AU. The CME was later observed in situ on April 20 by the Wind and BepiColombo spacecraft whilst BepiColombo was located very close to Earth. This CME presents a good opportunity for a triple radial alignment study, as the spacecraft were separated by less than 5° in longitude. The source of the CME, which was launched on April 15, was an almost entirely isolated streamer blowout. The Solar Terrestrial Relations Observatory (STEREO)-A spacecraft observed the event remotely from −75.1° longitude, which is an exceptionally well suited viewpoint for heliospheric imaging of an Earth directed CME.Aims.The configuration of the four spacecraft has provided an exceptionally clean link between remote imaging and in situ observations of the CME. We have used the in situ observations of the CME at Solar Orbiter, Wind, and BepiColombo and the remote observations of the CME at STEREO-A to determine the global shape of the CME and its evolution as it propagated through the inner heliosphere.Methods.We used three magnetic flux rope models that are based on different assumptions about the flux rope morphology to interpret the large-scale structure of the interplanetary CME (ICME). The 3DCORE model assumes an elliptical cross-section with a fixed aspect-ratio calculated by using the STEREO Heliospheric Imager (HI) observations as a constraint. The other two models are variants of the kinematically-distorted flux rope (KFR) technique, where two flux rope cross-sections are considered: one in a uniform solar wind and another in a solar-minimum-like structured solar wind. Analysis of CME evolution has been complemented by the use of (1) the ELEvoHI model to compare predicted CME arrival times and confirm the connection between the imaging and in situ observations, and (2) the PREDSTORM model, which provides an estimate of theDstindex at Earth using Solar Orbiter magnetometer data as if it were a real–time upstream solar wind monitor.Results.A clear flattening of the CME cross-section has been observed by STEREO-A, and further confirmed by comparing profiles of the flux rope models to the in situ data, where the distorted flux rope cross-section qualitatively agrees most with in situ observations of the magnetic field at Solar Orbiter. Comparing in situ observations of the magnetic field between spacecraft, we find that the dependence of the maximum (mean) magnetic field strength decreases with heliocentric distance asr−1.24 ± 0.50(r−1.12 ± 0.14), which is in disagreement with previous studies. Further assessment of the axial and poloidal magnetic field strength dependencies suggests that the expansion of the CME is likely neither self-similar nor cylindrically symmetric.

Effect of low-energy ion assistance on the properties of sputtered ZrB2 films

Zirconium diboride (ZrB2) films have been deposited by direct current magnetron sputtering (DCMS) from a ZrB2 compound target on Al2O3 (0001) substrates held at 600, 700, 800, and 900 °C, and with two different axial magnetic field strengths, 34 and 104 G, generated using a coil surrounding the substrate. Plasma probe measurements show an increase of the ion fluxes on floating-potential substrates of the two different configurations by a factor of 2.8 for 104 G compared to 34 G, while the ion energy remained relatively constant at ≈12 eV. Time-of-flight elastic recoil detection analysis (ToF-ERDA) show that films deposited with a magnetic field of 34 G are highly overstoichiometric with B/Zr ratios ≈2.4, while films deposited with 104 G exhibit a B/Zr ratios ≈2.1. The levels of oxygen and carbon in the films are below 1 at. % irrespective of growth conditions. X-ray diffraction (XRD) θ/2θ scans, complemented by pole figure measurements, reveal that all deposited films are 0001-oriented. XRD θ/2θ scans of the 000ℓ peak intensities and ω (rocking-curve) widths show increased ZrB2 crystal quality with increasing temperature for both magnetic field strengths. Minimum electrical resistivity of ≈100 μΩcm is achieved for an axial magnetic field of 104 G, independent of temperature.

Modeling Interplanetary Expansion and Deformation of Coronal Mass Ejections With ANTEATR‐PARADE: Sensitivity to Input Parameters

AbstractSpace weather predictions related to coronal mass ejections (CMEs) requires understanding how a CME is initiated and how its properties change as it propagates. Most predictions have been limited to the arrival time of a CME and include little to no information about the CME's internal properties. ANother Type of Ensemble Arrival Time Results‐Physics‐driven Approach to Realistic Axis Deformation and Expansion (ANTEATR‐PARADE) represents the most thorough description of the interplanetary evolution of CMEs in a highly computationally‐efficient model (Kay & Nieves‐Chinchilla, 2020, https://doi.org/10.1029/2020JA028911). presents the derivation of this model, where we have added an elliptical cross section to the original arrival time model ANTEATR and introduced internal magnetic and thermal forces that, combined with the drag, can alter the shape of the central axis and cross section. ANTEATR‐PARADE results include the transit time of CMEs, as well as the shape and size, propagation and expansion velocities, density, and magnetic field properties upon impact. We determine the dependence of each output on each of the ANTEATR‐PARADE input parameters. For a fast CME, we see that the parameterization of our thermal and magnetic models tends to be more important than the actual initial temperature or magnetic field strength. We extend to other CMEs and find that the sensitivities change with CME scale with thermal forces being more important for a weaker CME and magnetic forces being more important for a stronger CME. The most critical parameters for space weather predictions are the CME mass, the initial magnetic field strength, the adiabatic index, and the profile of the axial magnetic field strength.

Design of Symmetric Magnetic Lenses with Optimum Operational Conditions

In the present paper, the geometrical and optical object properties of symmetrical magnetic lens are designed and analyzed using the electron optical design (EOD) program. The effect of the axial aperture diameter (D), the air gap between the poles (s), the thickness of the poles (t), the excitation parameter NI of the lens are all studied for the best optical properties like the object focal length fo, the spherical and chromatic aberrations coefficients (Cs and Cc respectively). It was found that the optical properties of the object significantly improved with a decrease in the axial aperture diameter and width of the air gap of this lens. Upon our study, it was found that the best properties are achieved when the air gap width (S2 mm), and the axial hole diameter (D=6 mm). The effect of the electrode face thickness on the magnetic properties of the proposed magnetic lens is studied, it was found that the best magnetic properties and the highest value of magnetic flux and the lowest value of the axial magnetic field strength bandwidth were at electrode face thickness equal to (3 and 4 mm).Therefore, the best magnetic lens in our design with the best optical properties was S=2mm, D=6mm and t=3mm.

Implosion dynamics of triple-nozzle gas-puff z pinches on COBRA

Experiments on the 1-MA, 220-ns COBRA generator at Cornell University [J. B. Greenly et al., Rev. Sci. Instrum. 79, 073501 (2008)] were conducted to provide detailed measurements of structured cylindrical gas-puff z pinches. In the experiments, a 7 cm diameter triple-nozzle gas valve assembly with concentric outer and inner annular nozzles and a central gas jet initialize the z-pinch load with various working gases, radial density profiles, and externally applied axial magnetic fields. Planar laser-induced fluorescence provides a measure of the initial neutral gas density of the load, while three-frame laser shearing interferometry and multi-frame extreme ultraviolet (XUV) cameras reveal the formation and propagation of a magneto-Rayleigh–Taylor (MRT) unstable shock layer. Implosion trajectories are compared to simple, experimentally informed models and found to be in good agreement. Differences in the structure of the accelerating plasma sheath and evolution of the MRT instability are observed for different gas species and axial magnetic field strengths, correlating with differences in pinch uniformity and x-ray emission. The average instability growth is compared to linear MRT theory predictions using the instantaneous acceleration of the best-fit implosion models and characteristic instability wavelength, with the effective Atwood number and seed perturbation size as fit parameters. For high density argon center jets, ionization prior to the arrival of the imploding plasma sheath suggests a heating mechanism consistent with photoionization by XUV self-emission.

VLA Measurements of Faraday Rotation Through a Coronal Mass Ejection Using Multiple Lines of Sight

Coronal mass ejections (CMEs) are large eruptions of magnetized plasma from the Sun that play an important role in space weather. The key to understanding the fundamental physics of a CME is measurement of the plasma properties within heliocentric distances of $< 20~\mathrm{R}_{\odot }$ . Faraday rotation, a radioastronomical propagation measurement, is an extremely valuable diagnostic for studying CMEs. Faraday rotation measurements [RM] contain information on the magnetic field in the medium causing the Faraday rotation. Recent observations of CME-induced Faraday rotation (e.g., Howard et al. in Astrophys. J. 831, 208, 2016; Kooi et al. in Solar Phys. 292, 56, 2017; Bisi et al. in EGU General Assembly Conference Abstracts, 13243, 2017) have all been restricted to a single line of sight (LOS) and, therefore, limited to providing estimates of the magnetic field strength. Modeling by Liu et al. (Astrophys. J. 665, 1439, 2007) and Jensen and Russell (Geophys. Res. Lett. 35, L02103, 2008) demonstrated that multiple LOS are necessary to recover the magnetic field strength and structure of the observed CME. We report the first successful observations of Faraday rotation through a CME using multiple lines of sight: 13 LOS across seven target radio fields. We made these radio observations using the Karl G. Jansky Very Large Array (VLA) at $1-2$ GHz frequencies in the triggered operation mode on 31 July 2015, using a constellation of cosmic radio sources through the solar corona at heliocentric distances of $8.2-19.5~\mathrm{R}_{\odot }$ . For LOS within $10~\mathrm{R}_{\odot }$ , the CME’s contribution to the measured RM was $\approx 0$ to −20 rad m−2, a significant enhancement over the coronal contribution. We assumed a force-free flux-rope structure for the CME’s magnetic field and explored three separate models for the CME’s plasma density: constant density, thin shell, and thick shell. The plasma densities and axial magnetic field strengths for the three models ranged over $5.4-6.4\times 10^{3}$ cm−3 and $26-35$ mG, respectively. Further, using all 13 LOS, we successfully determined the CME’s orientation and helicity.

On the Radial and Longitudinal Variation of a Magnetic Cloud: ACE, Wind, ARTEMIS and Juno Observations

We present observations of the same magnetic cloud made near Earth by the Advance Composition Explorer (ACE), Wind, and the Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon’s Interaction with the Sun (ARTEMIS) mission comprising the Time History of Events and Macroscale Interactions during Substorms (THEMIS) B and THEMIS C spacecraft, and later by Juno at a distance of 1.2 AU. The spacecraft were close to radial alignment throughout the event, with a longitudinal separation of 3.6^{circ} between Juno and the spacecraft near Earth. The magnetic cloud likely originated from a filament eruption on 22 October 2011 at 00:05 UT, and caused a strong geomagnetic storm at Earth commencing on 24 October. Observations of the magnetic cloud at each spacecraft have been analysed using minimum variance analysis and two flux rope fitting models, Lundquist and Gold–Hoyle, to give the orientation of the flux rope axis. We explore the effect different trailing edge boundaries have on the results of each analysis method, and find a clear difference between the orientations of the flux rope axis at the near-Earth spacecraft and Juno, independent of the analysis method. The axial magnetic field strength and the radial width of the flux rope are calculated using both observations and fitting parameters and their relationship with heliocentric distance is investigated. Differences in results between the near-Earth spacecraft and Juno are attributed not only to the radial separation, but to the small longitudinal separation which resulted in a surprisingly large difference in the in situ observations between the spacecraft. This case study demonstrates the utility of Juno cruise data as a new opportunity to study magnetic clouds beyond 1 AU, and the need for caution in future radial alignment studies.

Resolving transient discharge cycle behaviour in modulated inductive plasmas

The further development of inductive plasma generators (IPGs) for space propulsion applications has driven the need for the development of non-intrusive experimental techniques that can resolve transient discharge cycle behaviour and accommodate a variety of propellant gases and gas-mixtures. In this work, a new approach is presented that simultaneously measures the antenna current, radially-resolved axial magnetic field strength and the radially-resolved emission in the visible range, at a sampling frequency sufficient to capture the driving and discharge cycle frequencies. Experiments were conducted using IPG7: a helical antenna IPG, driven nominally at 586 kHz, with 300 Hz discharge cycles. Nitrogen, argon-nitrogen, and argon-oxygen propellants were tested at capacitive and inductive conditions with input powers ranging from 4 kW to 36 kW. The propellants could be sourced from the space environment under in-situ resource utilisation. Analysis of the mean discharge cycle has made it possible to identify different coupling modes occurring within the cycle. These findings underscore the need to model such plasmas at the timescale of individual discharge cycles and demonstrate the value of the measured data for developing such models.

Investigation on explosive emission and attenuation processes of an intense current electron beam diode with annular graphite cathode via 24 framing camera

An experimental study of an intense current electron beam diode with a foil-free annular graphite cathode is carried out. The explosive emission images of a graphite cathode at discharging voltages of 240 kV and 780 kV and the attenuation images of cathode carbon ions at different magnetic fields are recorded using a 24-framing camera for the first time. The experimental results show that when the discharging voltage is 240 kV, the light spots of the plasma generated by the explosive emission process are randomly distributed over the annular cathode and the size and brightness of the light spots of the plasma are also randomly distributed; when the discharging voltage is 780 kV, if the background light generated by Čerenkov radiation is not taken into account, the light spots of the plasma generated by the explosion emission is more uniform than that when the discharging voltage is 280 kV and the brightness of the light spots of the plasma is higher, too. Meanwhile, when the axial magnetic field strength is less than 0.77 T, the plasma spots appear in the gap between the cathode and the anode. The smaller the axial magnetic field strength is, the higher the brightness of the plasma spots will be. In addition, when the discharging voltage is 780 kV/200 ns and the axial magnetic field strength is 0.77 T, a rough calculation indicates that the axial diffusion velocity of the cathode carbon ions ranges from 1.77 cm/μs to 2.1 cm/μs.

Model Fitting of Wind Magnetic Clouds for the Period 2004 – 2006

We give the results of parameter fitting of the magnetic clouds (MCs) observed by the Wind spacecraft for the three year period – 2004 to the end of 2006 (the “Present period”) using the force-free MC model of Lepping, Jones, and Burlaga (J. Geophys. Res.95, 11957, 1990). There were 19 MCs identified in the Present period, which was mainly in the declining phase of the solar cycle. The long-term occurrence rate of MCs is 10.3/year (1995-2015), whereas the occurrence rate for the Present period is only 6.3/year, similar to that for the period 2007-2009. Hence, the MC occurrence rate has had an appreciable decrease for the six years 2004-2009. The MC modeling gives such basic MC quantities as size, axial orientation, field handedness, axial magnetic field strength, center time, and closest approach vector. A statistically based modification of the modeled field intensity is tested. Also calculated are derived quantities, such as axial magnetic flux, axial current density, and axial current. Quality ( $Q_{0}$ ) estimates are assigned representing excellent (1), good/fair (2), and poor (3). We provide error estimates on the specific fit parameters for the individual MCs for the $Q_{0} =1,2$ cases, and give a distribution of MC types (i.e. N ⇒ S, S ⇒ N, All N, All S, etc., ten categories in all). There is an inordinately large percentage of the N ⇒ S type in the Present period (32%). The Present period basic model fitting results are compared to the results of the full Wind mission and other 3-year periods. First, we notice that during the Present period the MCs are, on average, significantly faster (by 21%), distinctly stronger in axial magnetic field (by 37%), and smaller in diameter (by 5.5%), than those in the Long-term period. The quality of the MCs in the Present period is significantly better than that of the Long-term period, where the ratio $N(Q_{0} =1,2)/N(Q_{0} =1,2,3)$ for each is 0.79 and 0.58, respectively. The Present period is quite different from the Long-term period (1995-2015), it is from the other three 3-year periods between 2006 and the end of 2015. In the Present period upstream shocks occur for the first 12 MCs of the 19 cases (63%); for comparison the Long-term rate is 56%.

Azimuthal surface waves in cylindrical metal waveguides partially filled by magnetoactive plasma: Analysis of energy transfer

Azimuthal surface waves are well known to be eigenwaves of cylindrical waveguide structures—plasma–dielectric–metal—placed into an external axial static magnetic field. The angular velocity of energy transfer along with the angular group velocity is applied to analyze electromagnetic energy rotation in these structures. Optimal magnitudes of effective azimuthal wavenumbers are determined for which the angular velocity reaches its maximum. The angular velocity is shown to decrease with the increasing absolute value of the azimuthal wavenumber and with the decreasing strength of the external axial static magnetic field.

An Observationally Constrained Analytical Model for Predicting the Magnetic Field Vectors of Interplanetary Coronal Mass Ejections at 1 au

Abstract We report on an observationally constrained analytical model, the INterplanetary Flux ROpe Simulator (INFROS), for predicting the magnetic field vectors of coronal mass ejections (CMEs) in the interplanetary medium. The main architecture of INFROS involves using the near-Sun flux rope properties obtained from the observational parameters that are evolved through the model in order to estimate the magnetic field vectors of interplanetary CMEs (ICMEs) at any heliocentric distance. We have formulated a new approach in INFROS to incorporate the expanding nature and the time-varying axial magnetic field strength of the flux rope during its passage over the spacecraft. As a proof of concept, we present the case study of an Earth-impacting CME which occurred on 2013 April 11. Using the near-Sun properties of the CME flux rope, we have estimated the magnetic vectors of the ICME as intersected by the spacecraft at 1 au. The predicted magnetic field profiles of the ICME show good agreement with those observed by the in situ spacecraft. Importantly, the maximum strength (10.5 ± 2.5 nT) of the southward component of the magnetic field (Bz) obtained from the model prediction is in agreement with the observed value (11 nT). Although our model does not include the prediction of the ICME plasma parameters, as a first-order approximation, it shows promising results in forecasting of Bz in near real time, which is critical for predicting the severity of the associated geomagnetic storms. This could prove to be a simple space-weather forecasting tool compared to the time-consuming and computationally expensive MHD models.

Development of an all permanent magnet ECR ion source for low and medium charge state ions production

An all permanent magnet Electron Cyclotron Resonance ion source-LAPECR1U (Lanzhou All Permanent magnet ECR ion source no.1 Upgraded), has been built at IMP in 2017 to satisfy the requirements of LEAF (Low Energy intense-highly-charged ion Accelerator Facility) for first two years commissioning. LAPECR1U was designed to be operated at 14.5 GHz to produce intense low and medium charge state ion beams. LAPECR1U features a compact structure, small size, and low cost. A cone-shape iron yoke in injection side and an iron plasma electrode in extraction side were used to enhance the axial magnetic field strength. The typical parameters and the preliminary beam results of the source are given in this paper.

Effect of Magnetization on Impedance Characteristics of a Capacitive Discharge Using Push-Pull Driven Cylindrical Electrodes

The impedance characteristics of a 13.56-MHz capacitively driven, symmetric magnetized discharge, created in argon and helium using an array of cylindrical electrodes, are presented. It is found that the discharge produced in argon is largely capacitive, while it tends to becoming inductive as the axial magnetic field strength increases. However, an opposing trend is seen in the case of helium discharge. On the other hand, the effective resistance is seen to continuously decrease for both helium as well as argon. The effect of increasing the radio frequency (RF) power levels is seen to have a marginal effect in the plasma density formed between the discharge electrodes, whereas the density rise is quite significant with the increase in the magnetic field. This behavior has been attributed to power mode transition from ion to electron heating inside the discharge.