Space Charge Limit Research Articles

Observation of Space Charge Limited Current in Schottky Diodes with V2O5 Interfacial Layer Prepared by Radio Frequency Magnetron Sputtering

Electrical properties of V2O5/n-Si Schottky barrier diodes prepared by rf magnetron sputtering of vanadium pentoxide (V2O5) on n-Si wafer have been investigated. The current-voltage (I–V) and capacitance-voltage (C-V) measurements of the diode have been performed in the dark at the room temperature. The saturation current (I0), ideality factor (n), barrier height (ΦB) values of the diode have been determined as 6.68x10-8 A, 1.35, and 0.755 eV, respectively. The series resistance (RS) values from Norde, Cheung and Nicollian & Brews methods have been determined as 199 Ω, 251 Ω, and 144 Ω, respectively. The energy distribution of interface state density (NSS) was determined, and the values of against the energy values of NSS in the vary between EC-0.462 eV and EC-0.713 eV were obtained 4.343x1016 eV-1 cm-2 and 3.282x1015 eV-1 cm-2, respectively. The barrier height and metal oxide thickness (ẟ) values using capacitance-voltage (C-V) measurements in the frequency of 1 MHz has also been calculated as 0.949 eV and 37.4 nm, respectively. The prepared diode showed abnormal diode characteristics, indicating the existence of a space-charge limited (SCL) current. From forward bias I-V characteristics, the ohmic, trapped filled space charge limited current (TFSCLC) and SCLC conduction behaviors were observed at low, middle, and high voltages, respectively. Experimental results indicated that the prepared V2O5 film on n-Si can be utilized in electronic applications.

An extraction system design with a strongly inhomogeneous electric field for a JYFL electron cyclotron resonance ion source

A new ECR ion source extraction system has been designed. The design is based on the extraction conditions of the JYFL 14 GHz ECRIS, and its performance is compared to the existing extractor via numerical modeling. The aim is to improve the formation and quality of high-intensity ion beams. The plasma and the puller electrodes shape were changed. The plasma electrode has a narrow tip extruding toward the puller. It causes the electric field to increase near the plasma meniscus and subsequent higher ion velocity growth rate, which leads to the beam space charge reduction at fixed current and acceleration voltage. The extractor was developed with the ion optical code IBSimu. The initial beam parameters were taken from the experimental data. The calculations showed that the new extraction system allows to increase the total extracted current without compromising the beam quality. The new design allows the beam formation optimization for lower extraction voltages overcoming the present space charge limit.

High-current space-charge-limited pulses using ultrashort laser pulses.

The maximum current that can be delivered by a 1-D vacuum diode is limited due to the space-charge reduction of the accelerating field. For a steady-state operation, this is given by the Child-Langmuir space-charge limit. However, for pulsed diode sources, the instantaneous current can be much higher than this limit, as long as the pulse length is much less than the transit time across the diode gap. This enables the generation of high current pulses with pulse durations of the order of tens of picoseconds using photocathodes driven by ultrashort laser pulses. The generation of such short and powerful electromagnetic pulses is important for numerous applications such as ultrawideband radar or as photocathode sources for accelerators. In this work, the limiting current pulse is investigated in the case of a very short, square-top initial pulse and it is found that these pulses propagate in a self-similar manner, remaining as a square-top charge cloud in space throughout their acceleration and propagation. The resultant current and pulse duration turn out to be dependent on only three parameters, which are the applied voltage, the vacuum transit time, and the fraction of the saturation charge density in the initial charge cloud. The resultant scaling of the resultant peak current and pulse duration are calculated numerically as a function of starting sheet-charge density, allowing the calculation of the resultant pulses for any ultrashort, pulse-driven vacuum photodiode design.

Space-charge affected current flow: an analytical verification solution for kinetic and fluid simulation models

Verification of numerical simulations is an important step in code development as it demonstrates the correctness of the code in solving the underlying physical model. Analytical solutions represent a strong tool in code verification, but due to the complexity of the fundamental equations, such solutions are often not always available. This is particularly true in the case of kinetic models. Here we present a family of fully analytical solutions describing current transmission between two electrodes and which apply to both fluid, and kinetic, descriptions of the system. The solutions account for the finite initial particle injection velocity and are valid for all injection currents between zero and the maximum at the space-charge limit. In addition to determining this space-charge limited current, spatial profiles of all physical quantities (such as the particle density and velocity) are also obtained at all injection currents. This provides a means to not only verify fluid and kinetic simulations, but also to assess the error and accuracy of the numerical simulation methods and parameters used. The analytical solutions extend the classical Child–Langmuir law (which only applies to the maximum transmissible current and an initial injection velocity equal to zero), and provide new insight into space-charge affected current flow.

A study on the influence of dose rate on total ionizing dose effect of anti-fuse field programmable gate array—The irradiation damage is attenuated at low dose rate

The TID (total ionizing dose) in-situ experiments of LC1020B, an anti-fuse FPGA (Field Programmable Gate Array) device, were designed and carried out under different dose rates, and the influence of dose rate on the TID effect of FPGA was studied. The experimental results show that: 1) the TID irradiation failure of the FPGA under different dose rates has nothing to do with the input voltage parameter exceeding the standard. 2) with the decrease of cobalt source irradiation dose rate [171, 26.83, and 2.68 mGy(Si)/s], the TID effect failure dose threshold [168, 229, and 334 Gy(Si), respectively] of the FPGA gradually increased, showing obvious attenuation of low dose rate damage. Theoretical analysis suggests that, compared with the space charge limitation effect, the oxide charge annealing effect plays a dominant role, and longer irradiation time is beneficial to the oxide charge annealing. And based on the experimental data, an FPGA TID analytical model with power consumption current as the damage characterization parameter is established, which lays a foundation for scientific evaluation of radiation effect of anti-fuse FPGAs.

The transition from thermionic to space charge limited emission for needle-like surfaces—A particle-in-cell simulation study

We perform particle-in-cell simulations of thermionic emission from hemi-ellipsoidal shaped needle emitters. The Schottky corrected Richardson–Dushman equation is used to compute the emitted current from the curved emitter surface. It is shown that the transmitted thermionic current increases with cathode temperature before eventually settling to the enhanced space charge limited (SCL) current. It is further shown that the critical temperature at which transition to the saturation region occurs increases with the height of the emitter, leading to a softening in the transition. This may be attributed to the non-uniformity in the cathode work function as in planar diodes. The SCL current is found to increase linearly with the electrostatic apex field enhancement factor as predicted recently [Singh et al., Phys. Plasmas 27, 104501 (2020)].

Operation voltage and illumination intensity dependent space-charge limited current conductions in vertical organic phototransistors based on CuPc/C60 heterojunction and graphene

For a trap-free single layer single carrier (hole-only or electron-only) organic device of thickness d, dielectric constant εr, and mobility μ, the relation of current density j with voltage V is described by the well-known Mott–Gurney equation, j=9ε0εrμV2/8d3, which can be rewritten as j=GV, where G=9ε0εrμ/8d3 can be called space-charge limited (SCL) conductance. We investigated the current–voltage characteristics of vertical organic heterojunction phototransistors based on graphene as the source and C60/copper phthalocyanine (CuPc) heterojunction as the photoactive layer. We found that the drain current vs drain voltage (Id-Vd) characteristic is composed of two distinct SCL conductions with SCL-conductance being strongly dependent on the gate voltage and illumination intensity. At low gate voltages, the Id-Vd curve can be divided into two sections of SCL current conduction with different SCL-conductance: the lower conductance in the lower drain voltage range and the higher conductance in the higher drain voltage range. Both low and high SCL-conductance increase with the gate voltage and illumination intensity. However, as the gate voltage increases to a certain threshold, the two SCL sections unify to only one with the conductance being between them. Our findings implicate that the current conduction of an ideal vertical organic phototransistor (VOPT), whose source/organic interface contact is Ohmic and organic semiconductor is trap free, can be well modeled by the SCL conduction theory with carrier density dependent mobility, which is strongly related to the gate voltage and illumination intensity, and that the mobility of VOPTs at a certain gate voltage can be extracted by the Mott–Gurney equation.

Theoretical Linkage of Thermionic, Field, and Space-Charge Limited Emission for a Vacuum Crossed-Field Gap

Crossed-field devices, such as magnetrons and crossed-field amplifiers, where an external magnetic field is orthogonal to the electric field across the gap, are used in radars, communications systems, and material processing. Improving the efficiency and power density of crossed-field devices requires a robust understanding of electron emission, particularly when multiple emission mechanisms may contribute, such as for thermionic and field emission. Previous studies of nonmagnetic diodes have theoretically identified the transitions, or nexuses, between multiple electron emission mechanisms by examining the relevant equations defining each individual mechanism and then derived exact theoretical solutions that combined these mechanisms and approached the standard emission equations under appropriate limits. This work extends those studies by incorporating the orthogonal magnetic field and assessing the transitions between the Richardson–Laue–Dushman (RLD) formulation for thermionic emission, the Fowler–Nordheim (FN) equation for field emission, the space–charge limit given by both the general (for nonzero electron injection velocity) and (zero electron injection velocity) Child–Langmuir (CL) (generalized CL (GCL) and CL, respectively) laws for space–charge limited current, and the space–charge limited current for a noninsulated (magnetic field below the Hull cutoff) and insulated (magnetic field above the Hull cutoff) diode. We derive exact solutions for the current density for these mechanisms and demonstrate their asymptotic behavior under relevant conditions. Furthermore, we plot the exact solution of current density <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$J$ </tex-math></inline-formula> as a function of applied voltage <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V$ </tex-math></inline-formula> by incorporating the general thermo-field emission theory for the current source and demonstrate the transition between each emission mechanisms with increasing <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V$ </tex-math></inline-formula> for various temperatures and fixed ratios of magnetic field to the Hull cutoff. We also construct nexus plots to identify transitions between the various regimes for different conditions.

A Tutorial on Calculating Space-Charge-Limited Current Density for General Geometries and Multiple Dimensions

Space-charge-limited current (SCLC) remains a critical issue across material phases (vacuum, gas, liquids, and solids) and timescales. The solution for one-dimensional (1D), planar SCLC density (SCLCD), referred to as the Child–Langmuir (CL) law, remains the common benchmark for these calculations; however, practical devices are neither 1D nor planar. This article reviews recent progress on developing approaches to derive SCLCD for nonplanar and multidimensional diodes. First, we summarize the application of variational calculus (VC) to derive 1D SCLCD based on minimizing the current in the gap. We also describe the nuances of applying Poisson’s equation to 1D nonplanar diodes compared to three-dimensional (3D) geometries. We next discuss the application of conformal mapping (CM) to extend 1D, planar SCLCD to more complicated 1D geometries, including a detailed justification of the application of CM for solving Poisson’s equation. We then discuss the application of vacuum capacitance and a generalized relationship between the electric potential in vacuum and space-charge-limited (SCL) diodes to derive exact analytic solutions for SCLCD in two-dimensional (2D) and 3D diodes with emission from the full cathode. We further relate the SCLCD for 3D planar square and disk electrodes across a wide range of electrode sizes. We conclude by discussing future theoretical and practical extensions of these approaches.

9.14-Mbps 64-PPM UWOC system based on a directly modulated MOPA with pre-pulse shaping and a high-sensitivity PMT with analog demodulation.

A pulsed fiber master oscillator power amplifier (MOPA), which is combined with second harmonic generation (SHG) and modulated by directly changing the current of the low-power seed laser, is designed in this paper to overcome the 'green gap' of semiconductor lasers and the difficulty of obtaining high-power and wide-bandwidth driving circuits. To decrease the guard slot and increase the data rate of a high-order pulse position modulation (PPM) system, pre-pulse shaping (PPS) is utilized to decrease the fluctuation of pulse power, which is caused by the gain dynamics of multi-order amplification of the MOPA, from 55.6% to 27.5% for 25-ns pulses and from 22.4% to 16.7% for 10-ns pulses, respectively. Moreover, an analog PPM demodulation method is proposed to mitigate the nonlinear effect caused by space charge limitations at dynodes of a photomultiplier tube (PMT) and increase the robustness of the system. In an optical darkroom, a 99-m 64-PPM UWOC transmission, of which the measured link loss is around 13.16 attenuation length (AL), is realized in a water tank with a data rate of 9.14 Mbps. The average received optical power ranges from -60.87 to -52.51 dBm, corresponding to a bit error rate (BER) range of 1.93 × 10-4 to 2.3 × 10-3. To further prove the reliability of the proposed system, we implement a 65-m UWOC experiment with the same data rate at a BER of 3.42 × 10-4 in a 50-m standard swimming pool. The maximum link loss is measured to be 15 AL.

Numerical simulation of a relativistic magnetron using a fluid electron model

An approach to numerically modeling relativistic magnetrons, in which the electrons are represented with a relativistic fluid, is described. A principal effect in the operation of a magnetron is space-charge-limited (SCL) emission of electrons from the cathode. We have developed an approximate SCL emission boundary condition for the fluid electron model. This boundary condition prescribes the flux of electrons as a function of the normal component of the electric field on the boundary. We show the results of a benchmarking activity that applies the fluid SCL boundary condition to the one-dimensional Child–Langmuir diode problem and a canonical two-dimensional diode problem. Simulation results for a two-dimensional A6 magnetron are then presented. Computed bunching of the electron cloud occurs and coincides with significant microwave power generation. Numerical convergence of the solution is considered. Sharp gradients in the solution quantities at the diocotron resonance, spanning an interval of three to four grid cells in the most well-resolved case, are present and likely affect convergence.

Characterization and minimization of the half-integer stop band with space charge in a hadron synchrotron

In any hadron synchrotron, the half-integer resonance is among the strongest effects limiting the achievable maximum beam intensity. The heavy-ion superconducting synchrotron SIS100, currently under construction at GSI, should provide intense beams for the future FAIR experiments. Using SIS100 as an example, this paper develops a quantitative framework for characterizing the half-integer stop band for realistic, Gaussian-like distributed bunched beams. This study identifies the tune areas affected by the gradient-error-induced half-integer resonance for varying space charge strengths. A key insight of our analysis is that, for bunched beams a relatively small gradient error can result in a large half-integer stop band width. The achievable maximum bunch intensity, often referred to as space charge limit, is thus reduced significantly. This contrasts the findings in existing studies in literature based on more simplified beam distributions. The reason for discrepancy is identified in the increasing stop band width for Gaussian distributions when space charge becomes stronger, which appears on longer time scales as relevant for synchrotrons. The role of synchrotron motion in providing continuous emittance growth across the bunch is scrutinized. To minimize the half-integer stop band for a bunched beam, and hence increase the space charge limit, lattice corrections are applied: Including space charge in the optimization procedure recovers results equivalent to conventional lattice correction. Therefore, we find that conventional correction tools are well suited to increase the gradient-error-induced space charge limit of synchrotrons.

Investigation of Charge Accumulation and Decay Processes in Epoxy-Based Composites Using Quantum Chemical Calculations Under the Effect of Electric Field

This work investigates the influence of aluminum nitride (AlN) fillers on the charge dynamics of epoxy resin (EP) and its hybrid composites through space charge measurements and quantum chemical calculations (QCCs). QCCs analyze the energy-level orbitals and trap parameters of the molecules under the electric field. The pure EP exhibits a homo-charge accumulation, whereas fewer charges are accumulated in the EP hybrid composites. The AlN filler addition significantly suppresses the space charge accumulation during polarization and facilitates the charge dissipation during the depolarization due to the lower trap density than the pure EP. It is found that the orbital energy level of the combined reaction of all monomers together is not a simple superposition of individual orbital energy levels of different monomers. The increased charge injection barrier height suppresses space charge injection and accumulation. The electric field significantly influences the hole traps more than the electron traps. The positive charges with low mobility are easily trapped inside hole traps compared with the negative charges with high mobility inside the electron traps. This results in positive charge accumulation during the polarization and slow decay during the depolarization. The increase of the electrostatic potential is more uniform in hybrid composites than in the pure EP, and no visible electron migration is observed. It indicates that hybrid composites remain stable under electric fields. Moreover, it is not easy for the hole to transport due to the deep trap after the charge injection, leading to limited visible space charge accumulation near the anode.

Analysis of electrical parameters of p-i-n perovskites solar cells during passivation via N-doped graphene quantum dots

Metal halide perovskite (PVSK) solar cells (PSCs) have arisen as emerging photovoltaics (PV) technology. Nevertheless, due to defects in the organic-inorganic metal-halide PVSK layer, the conversion efficiency (η) and the stability are hampered. Thus, the passivation of the perovskites layer is vital to obtain stable PSCs against temperature and humidity. Due to the introduction of the N-doped graphene quantum dots (NGQDs) interlayer at the PVSK/electron transport layer (ETL) interface, recombination in the PSCs is greatly suppressed. The NGQDs layer promotes charge transportation in the PVSK layer as well as at the PVSK/ETL interface, which enhances the performance of the PSCs. The performance of the PSCs is governed by the cell's electrical parameters.Thus, the electrical parameters are analyzed during PSC passivation. PVSK passivation with NGQDs consequences in the upsurge of the recombination lifetime (from 31.7 to 59.9 ns), improves the interfacial charge transfer and suppresses the trap density from 5.53×1016 cm−3 to 4.68×1016 cm−3, which are confirmed through photoluminescence, electrochemical impedance spectroscopy (EIS) and space charge limited (SCL) measurement, respectively. The conversion efficiency of the NGQDs passivated PSC is boosted to 17.10%, which is ∼13.8% higher than the control cell (η ∼15.03%, un-passivated PSC). Furthermore, the PV cell parameters are determined analytically, which revealed that both the ideality factor (n) and leakage current (J0) reduced to 1.2409 and 1.37 × 10−16 A/cm2, respectively (n = 1.6114 and J0 = 4.24 × 10−13 A/cm2 of the control cell). The present work synergically improves the charge transport and suppresses the non-radiative recombination losses in PSCs via defect passivation through NGQDs which are essential for further advancement of the device performance and operational stability.

Simulation study of the space charge limit in heavy-ion synchrotrons

The SIS100 synchrotron as a part of the new Facility for Antiproton and Ion Research (FAIR) accelerator facility at GSI should be operated at the ``space charge limit'' for light- and heavy-ion beams. Beam losses due to space-charge-induced resonance crossing should not exceed a few percent during a full cycle. The recent advances in the performance of particle tracking tools with self-consistent solvers for the 3D space charge forces now allow us to reliably identify low-loss areas in tune space, considering the full SIS100 accumulation plateau of one second (160 000 turns) duration. A realistic magnet error model, extracted from precise bench measurements of the SIS100 main dipole and quadrupole magnets, is included in the simulations. Previously, such beam dynamics simulations required non-self-consistent space charge models. By comparing to the self-consistent simulations results, we are now able to demonstrate that the predictions from such faster space charge models can be used to identify low-loss regions with sufficient accuracy. The findings are applied by identifying a low-loss working point region in SIS100 for the design FAIR beam parameters. The bunch intensity at the space charge limit is determined. Several countermeasures to space charge are proposed to enlarge the low-loss area and to further increase the space charge limit.

Experimental investigation of the mobility in the ITIC single crystal based field-effect transistor

The A-π-A electron acceptors, e.g. ITIC and its derivatives have attracted tremendous attention for optoelectronic applications since they can catch up with or even surpass the high performances based on the fulleren-based devices. The charge transport in the A-π-A electron acceptor depends heavily on the molecular packing structure. Tremendous theoretical works have been performed to investigate the correlation between the intermolecular arrangement and the mobility of A-π-A electron acceptors. The studies have simulated the mobility comparison between ITIC crystal and thin film. Although some researchers have measured the mobility of the ITIC thin films using space charge limit current (SCLC) technique and field-effect transistor (FET) measurement, the direct mobility measurements of ITIC crystals remain scarce. In this work, the ITIC single crystal nanosheets were grown by the solvent-non-solvent interfacial precipitation method, providing an effective way to investigate the mobility difference between the ITIC amorphous films and the ITIC single crystals. The measurements unravel that the resulting ITIC cystal has an edge-to-face stacking structure and it is anisotropic. The corresponding OFETs have been fabricated to investigate their mobilities: the single crystal devices exhibit mobility up to 5.4 × 10−2 cm2V−1s−1 while the amorphous ITIC film has a mobility of 2.1 × 10−3 cm2V−1s−1. This experimental result is consistent with the previous theoretical prediction and demonstrates that the crystalline ITIC has a more effective charge transport path along the b crystallographic axis than the amorphous film. This work provides a method to investigate the intrinsic charge transport property of the ITIC crystal.

Properties of Halide Perovskite Photodetectors with Little Rubidium Incorporation.

This study investigates the effects of Rb doping on the Rb-formamidinium-methylammonium-PbI3 based perovskite photodetectors. Rb was incorporated in the perovskite films with different contents, and the corresponding photo-response properties were studied. Doping of few Rb (~2.5%) was found to greatly increase the grain size and the absorbance of the perovskite. However, when the Rb content was greater than 2.5%, clustering of the Rb-rich phases emerged, the band gap decreased, and additional absorption band edge was found. The excess Rb-rich phases were the main cause that degraded the performance of the photodetectors. By space charge limit current analyses, the Rb was found to passivate the defects in the perovskite, lowering the leakage current and reducing the trap densities of carriers. This fact was used to explain the increase in the detectivity. To clarify the effect of Rb, the photovoltaic properties were measured. Similarly, h perovskite with 2.5% Rb doping increased the short-circuit current, revealing the decline of the internal defects. The 2.5% Rb doped photodetector showed the best performance with responsivity of 0.28 AW−1 and ~50% quantum efficiency. Detectivity as high as 4.6 × 1011 Jones was obtained, owing to the improved crystallinity and reduced defects.

Kinetic analysis of the plasma sheath around an electron-emitting object with elliptic cross section.

The structure of the sheath and the current exchange of two-dimensional electron-emitting objects with elliptic cross section immersed at rest in Maxwellian plasmas are investigated with an energy-conserving stationary Vlasov-Poisson solver free of statistical noise. The parameter domains for current collection within the orbital-motion-limited (OML) regime and current emission in space-charge-limited (SCL) conditions were studied by varying the characteristic dimension of the ellipse, its eccentricity, and the emission level. The analysis reveals the correlations between the onset of the non-OML and SCL regimes and the local curvature of the ellipse. As compared to nonemitting ellipses, electron emission broadens the parameter domain for OML current collection for ions and reduces considerably the current drop for non-OML conditions. Under identical plasma environments, elliptic bodies are more prone to operate under non-OML and SCL conditions than cylinders. Their emitted current in SCL conditions can be computed accurately from well-known results for cylinders if appropriate dimensionless variables and an equivalent radius are used. The role of the eccentricity, which acts as an integrability-breaking parameter, on the filamentation of the distribution function of the attracted species is studied.

Parametrization of current–voltage characteristics and operation domains of cylindrical emissive probes in collisionless Maxwellian plasmas at rest

Important progress has recently been made on the Orbital Motion Theory for cylindrical emissive probes immersed at rest in collisionless and Maxwellian plasmas. However, due to the computational cost of its numerical algorithm, only solutions for specific values of the physical parameters were found, thus preventing its direct application to the interpretation of experimental current–voltage characteristics ( curves). In this work, and thanks to an analytical analysis of a Jacobian matrix appearing in the algorithm, the computational cost was reduced by a factor in the order of , where is the number of grid points. This achievement, together with the implementation of parallel programming, allowed to construct a database with more than 18 000 curves for a broad range of physical parameters, including the emission level, the probe radius-to-Debye length, and the ion-to-electron temperature ratios. The boundaries in parameter space of the operational regimes of emissive probes, covering both orbital motion limited (OML) and space charge limited (SCL) transitions were computed. A novel OML/non-OML transition for emissive probes operating at low bias was found. The numerical results were used to propose useful analytical laws for the SCL boundary happening at negative bias, the reduction of the emitted electron current due to SCL effects, and the floating potential of emissive probes. The applications of the results to the modeling of low work function tethers and three experimental methods for measuring the plasma potential, i.e. the separation point, the inflection point, and the floating potential techniques, were discussed. The formation of an inverse sheath for strong emission was investigated.

Evaluation of Computational Models for Electron Transpiration Cooling

Recent developments in the world of hypersonic flight have brought increased attention to the thermal response of materials exposed to high-enthalpy gases. One promising concept is electron transpiration cooling (ETC) that provides the prospect of a passive heat removal mechanism, rivaling and possibly outperforming that of radiative cooling. In this work, non-equilibrium CFD simulations are performed to evaluate the possible roles of this cooling mode under high-enthalpy conditions obtainable in plasma torch ground-test facilities capable of long flow times. The work focuses on the test case of argon gas being heated to achieve enthalpies equivalent to post-shock conditions experienced by a vehicle flying through the atmosphere at hypersonic speed. Simulations are performed at a range of conditions and are used to calibrate direct comparisons between torch operating conditions and resulting flow properties. These comparisons highlight important modeling considerations for simulating long-duration, hot chamber tests. Simulation results correspond well with the experimental measurements of gas temperature, material surface temperature as well as measured current generated in the test article. Theoretical methods taking into consideration space charge limitations are presented and applied to provide design suggestions to boost the ETC effect in future experiments.