High-voltage Spark Discharge Research Articles

Experimental simulation of the generation of microwave radiation during the interaction of a lightning discharge with an aircraft

On a specialized testing installation — a high-voltage Marx generator, which allows the formation of a spark discharge up to 20 meters long, the process of the impact of lightning radio emission in the microwave range on an aircraft (AC) is simulated. A metal AC model made on a scale of 1:50 was placed in a 9 m long rod-plane spark gap. A positive voltage pulse was applied to the high-voltage electrode from the generator (front 100 μsec, duration 7500 μsec). The generated spark discharge passed through the AC model. It was found that when the spark channel passes through the body of the model, electromagnetic pulses of the microwave range with a duration of less than 500 psec and a rise time of less than 100 psec arise. The measurement of the resulting microwave pulses was carried out using special radio equipment in the subnanosecond range. High-speed photography of the discharge development, carried out synchronously with electromagnetic measurements, showed that microwave pulses (up to 10 GHz) arise at the stage of development of the spark discharge leader in the part of the “high-voltage electrode – insulated model” gap. Such pulses can be considered as a factor dangerous for various AC microwave radio systems, when the AC is struck by lightning, as well as for other objects, including power facilities, which contain equipment with microelectronics. Such microwave pulses can also occur during nearby lightning discharges (for example, in a lightning rod of a power substation), when a powerful streamer corona occurs on devices and wires of ultra-high voltage lines), and when a high-voltage spark discharge occurs when switching equipment (disconnectors, arresters) is triggered. In this case, disruptions are possible in the operation of control equipment (for example, relay protection devices) that contains microelectronics, as well as various communication means available at electric power facilities operating in the microwave range (above 1 GHz).

A generalized physical principle of development of plasma channel of a high-voltage pulse spark discharge in a dielectric

Goal. Development of the generalized physical principle of development of plasma channel of a high-voltage electrical pulse spark discharge in the homogeneous dielectric of the different aggregate state. Methodology. Basis of physical optics, theoretical electrical engineering, electrophysics bases of technique of high-voltage and large pulse currents, bases of high-voltage pulse technique and measuring technique. Results. Development of physical principle of development of plasma channel of an electric pulse spark discharge is executed in a homogeneous gas dielectric on the applied example of the use in calculations and experiments of the double-electrode discharge system (DEDS) with a long air interval, testing action of standard interconnect аperiodic pulse of high-voltage of temporal shape of Tm/Тd≈200 μs/1990 μs of positive polarity. The generalized formula is got for the calculation of total length of lc of the real way of development of an pulse spark discharge in an air dielectric, which allowed to formulate the offered physical principle in the following kind: «The plasma channel of an pulse spark discharge in a gas dielectric spreads from one of its points to other after a way length of lc, providing the least falling on it of electric voltage of Uc». It is shown that this principle in the first approaching can be applied and to the homogeneous liquid and hard dielectrics. Comparison of the developed physical principle of distribution of plasma channel of an electrical spark discharge is executed in a dielectrical environment with fundamental Fermat physical principle (a law) for distribution of light in an optically transparent environment, which specifies on mathematical likeness and closeness on destiny of these physical principles. Calculation estimations of falling of electric voltage of Uc on total length of lc of the real zigzag way of development in the air dielectric of DEDS a «edge-plane» with the least length of its discharge interval of lmin=1,5 m is presented, that a value Uc does not exceed 9 % from the experimental level of aggressive voltage of Umd≈611,6 кV in this DEDS for the аperiodic pulse of voltage of Tm/Тd≈200 μs/1990 μs. It is set that the estimated time of td advancement of leader channel of electric pulse discharge in air DEDS (lmin=1,5 m) on its real way total length of lc≈1,53 m makes td≈15,3 μs, and experimental duration of cut of Tdc of the indicated аperiodic impulse of voltage utilized in experiments, characterizing time of short circuit by the plasma channel of discharge of air interval in DEDS, appears equal Тdc≈td≈17 μs. Originality. The generalized physical principle of development of plasma channel of a high-voltage electrical pulse spark discharge is first developed in the homogeneous dielectric of the different aggregate state. Practical value. Application in electrical engineering practice and high-voltage pulse technique of the offered principle of distribution in the dielectrics of plasma channel of an pulse spark discharge will allow to develop both new and to perfect the existent methods of computer design of electro-discharge processes in the gas, liquid and hard insulation of different high-voltage electrical power engineering and electrophysics devices, directed on the increase of reliability of their operation.

Effect of high-voltage spark discharges on reduction of the concentration of total bacterial count in wastewater

The limited supply of fresh water on the planet stimulates the reuse of wastewater in various areas. It is proposed to use disinfected wastewater for irrigation in agriculture. The possibility of reducing the total bacterial count in wastewater by high-voltage spark discharges using a developed experimental setup has been investigated. The total bacterial count was measured by the rapid method using a luminometric mini-laboratory EnSURE Touch and a standard method for counting bacteria, capable of forming colony-forming units on nutrient agar. Wastewater from the Zhulebinsky storm collector with an initial concentration of 1012 CFU ml−1 with a volume of 103 ml is disinfected up to the norm 6 log in 120 s with capacitance 0.1 μF and in 180 s with capacitance 0.05 μF. Wastewater from the Kuryanovsky storm channel with an initial concentration of 109 CFU ml−1 with a volume of 103 ml is disinfected up to the norm 6 log in 100 s with capacitance 0.1 μF and in 160 s with capacitance 0.05 μF. To reduce the concentration of total bacterial count by 1 log, the minimum duration of disinfection of 103 ml of wastewater it took about 30 s at a discharge energy of 5 J ml−1. The advantages of bacterial inactivation in wastewater by high-voltage spark discharges were revealed, such as low operating voltage of 10 kV, high energy efficiency of 600 J l−1 and capacity 30 l h−1, increased service life and operational reliability, portability and environmental friendliness.

Studies of electric and spectral characteristics of surface spark discharge in atmosphere of carbon dioxide. Conversion of CO2 and CO2:H2 to CO

The results are presented from studies of the high-voltage pulse-periodic surface spark discharge propagating along the water-gas interface. In the case of CO2 or CO2:H2 mixture used as gaseous medium, the plasma-chemical conversion of CO2 to carbon monoxide CO was also studied. In the experiments, we used the generator with reservoir capacitor energy of 1.6 J, a voltage of 20 kV, and pulse duration of 2–3 μs. The average velocity was determined of the discharge propagation along the water surface in the CO2, CH4 and Ar atmospheres. It was shown that the leader velocities in the CO2 and CH4 atmospheres coincide, and they turned out to be 3–4 times lower than that in the Ar atmosphere. The integrated emission spectra are presented of the discharge in the CO2 atmosphere, in which the lines corresponding to CO2, CO, Hα, Hβ, and OI are distinguished. The electron concentration in the discharge channel was Ne = 1017 cm-1. The dynamics of conversion of CO2 to CO was traced at different energies inputted into the discharge. For the discharges in the atmospheres of CO2 and CO2:3H2 mixture, the degrees of conversion were 24 and 61%, respectively. And in the quasi-linear stage, the energy efficiencies of conversion were ∽13 and ∽6 eV per molecule for the CO2 and CO2:3H2 atmospheres, respectively.

Synthesis and Surface Engineering of Carbon Quantum Dots by Electrical Discharges Generated Inside and in Contact with Liquid

In this paper electrical discharge plasma in liquid was used for synthesis of carbon NPs. In addition, targeted changes of the NPs surface properties could be selectively achieved via treatment of as-prepared NPs by a gas-liquid interfacial discharge produced in contact with the colloidal solution. For synthesis a high-voltage spark discharge was ignited in the solution between two graphite electrodes immersed in water. The discharge in contact with liquid was generated between a stainless-steel capillary electrode served as cathode and the surface of the liquid. The discharge was ignited by applying the high voltage of 3.6 kV using a dc power supply with argon flowing through the capillary tube. The discharge current was kept constant in the range of 1 - 5 mA [1, 2].The composition, morphology and optical properties of the synthesized and plasma treated NPs were studied by TEM, EDX, PL, FTIR, Raman and ultraviolet–visible spectroscopy The NPs obtained by the spark discharge in water looked like isolated spherical NPs with the average diameter about 3 nm as it followed from the TEM analysis. The HRTEM images of separate particles revealed that particles are crystalline and the measured interplanar distances were found to be 2.06 Å that correspond to the reflections between (111) planes in carbon having diamond-like structure. The SAED analysis further proved the formation of diamond-like structures with admixture of orthorhombic carbon phases, while the rings corresponding to graphitic structure were absent in the SAED patterns.For the further studies of the prepared C NPs Raman and XRD techniques were used. The Raman spectrum contained two distinct peaks: narrow G-band near 1578 cm-1 attributable to the ordered graphite and the broadened D-band at 1349 cm-1 which is associated with disodered carbon and the presence of a carbon sp3 defects in the prepared C-NPs. It should be noted that the D-band is rather broad thus covering the range 1310-1320 cm-1, typical to the diamond and orthorhombic carbon structures.Analogically, the results of the X-ray diffraction studies exhibited the broad peak in the region 20-40˚, so-called halo, indicated a presence of small particles with various carbon phases in the sample. Nevertheless, the diamond-like phases, observed in TEM measurements most probably are presented in the sample but only as very small particles that are produced through the condensation mechanism. It is known that NPs in electrical discharge are formed through two competing mechanisms namely via the condensation of the evaporated electrode material that are atoms, ions and small clusters with their subsequent growth into the NPs; and in result the destroying of the electrodes with the formation of the particles of much larger sizes. For the Raman studies, the colloid was deposited onto the substrate, and thus larger and better crystallized particles with graphite structure formed by the second route were dominant that can explain the contradiction of Raman and TEM results.To modify the properties of NPs, the colloidal solution of C NPs synthesized by spark discharge was treated by reactive non-equilibrium gas-liquid discharge plasma contacting with the solution. The results of these studies showed that different surface chemistry activated in different solutions could be due to different reactions induced by plasma electrons at the plasma–solution interface compared to plasma–water one. Changing the surface groups is believed to be effective in improvement of photoluminescence properties of the synthesized C-dots.Thus, the EDL technique has been demonstrated to be suitable for the preparation of carbon quantum dots with sizes 2-5 nm and narrow size distribution that are the part of the requirements for practical applications. In addition, a treatment of NPs by reactive non-equilibrium gas-liquid discharge plasma contacting with a colloidal solution can offer great opportunities for the NPs surface engineering and an improvement of the photoluminescent properties. Carbon NPs with size less than 10 nm – so called quantum dots due to their excellent biocompatibility, chemical inertness, and size-selective photoluminescence properties may find increasing applications in modern biotechnology as more suitable alternatives to the traditional semiconductor quantum dots.The work was supported by the National Academy of Sciences of Belarus under project Convergence 2.4.06.[1] A. Nevar, N. Tarasenka, M. Nedelko, N. Tarasenko Carbon Lett. – 2020 https://doi.org/10.1007/s42823-020-00147-9.[2] V.S. Burakov, V.V Kiris, M.I. Nedelko, N.N. Tarasenka, A.A. Nevar, N. V. Tarasenko, Eur. Phys. J. Appl. Phys., 79 10801 (2017)

Physicomathematical models of seeds and errors in calculating the volume of an electro terminator filled with seeds

The article provides data on the impact of high-voltage current of electric spark discharges on the culture of gummosis located on the surface of cotton seed, and the article presents data on the impact of high-voltage electric spark discharges on the gummose culture located on the surface of the cotton seed. In this case, cotton seeds were taken as the basis for the physical model, consisting of three component parts, respectively, having a chalazal part, a lateral part, and a micropile. In the initial period of seed treatment, moisture penetrates the inside of the seed from the outside. Studied three-dimensional volumetric figures (hemisphere, cylinder, cone, etc.), carried out a literature review and mathematical calculations determined the calculation errors. The vessels of various shapes were compared. The prerequisites for determining the calculation errors have been made.

Experimental Investigation and Mechanism Analysis on Rock Damage by High Voltage Spark Discharge in Water: Effect of Electrical Conductivity

High voltage spark discharge (HVSD) could generate strong pressure waves that can be combined with a rotary drill bit to improve the penetration rate in unconventional oil and gas drilling. However, there has been little investigation of the effect of electrical conductivity on rock damage and the fragmentation mechanism caused by HVSD. Therefore, we conducted experiments to destroy cement mortar, a rock-like material, in water with five conductivity levels, from 0.5 mS/cm to 20 mS/cm. We measured the discharge parameters, such as breakdown voltage, breakdown delay time, and electrical energy loss, and investigated the damage mechanism from stress waves propagation using X-ray computed tomography. Our study then analyzed the influence of conductivity on the surface damage of the sample by the pore size distribution and the cumulative pore area, as well as studied the dependence of internal damage on conductivity by through-transmission ultrasonic inspection technique. The results indicated that the increase in electrical conductivity decreased the breakdown voltage and breakdown delay time and increased the energy loss, which led to a reduction in the magnitude of the pressure wave and, ultimately, reduced the sample damage. It is worth mentioning that the relationship between the sample damage and electrical conductivity is non-linear, showing a two-stage pattern. The findings suggest that stress waves induced by the pressure waves play a significant role in sample damage where pores and two types of tensile cracks are the main failure features. Compressive stresses close horizontal cracks inside the sample and propagate vertical cracks, forming the tensile cracks-I. Tensile stresses generated at the sample–water interface due to the reflection of stress waves produce the tensile cracks-II. Our study is the first to investigate the relationship between rock damage and electrical conductivity, providing insights to guide the design of drilling tools based on HVSD.

Effect of CO2 dilution on forced ignition and development of CH4/air ignition kernels

Reliable ignition of reactant mixtures containing combustion products is important to the function of many practical combustion devices. Prior work has considered the influence of CO2 on ignition delay times and laminar flame speeds. This work examines the effects of dilution with CO2 on forced ignition and development of ignition kernels in CH4/air mixtures. Ignition kernels were initiated by a high voltage spark discharge in CH4/air/diluent mixtures with a bulk velocity of 5 m/s and with 0.7 ≤ Φ ≤ 0.8. Ignition probabilities and kernel growth rates were determined from radiation intensity measurements collected using a Telops MS-IR FAST infrared camera. Nitrogen was used as an inert in a subset of conditions to facilitate identifying changes in chemistry associated with dilution by CO2. Chemistry effects of diluents on ignition were isolated by examining undiluted, N2 diluted, and CO2 diluted flows with equivalent adiabatic flame temperatures. Dilution with CO2 reduced the probability of ignition relative to undiluted and N2 diluted conditions with the same adiabatic flame temperature. Ignition kernels diluted with CO2 also tended to be smaller than those initiated in both undiluted and N2 diluted mixtures, with reduced growth rates.

Preparation of nanosized nickel powder by direct-current electrolysis combined with high-voltage spark discharge

The possibility of obtaining nanosized nickel powder by simultaneous dc electrolysis and high-voltage spark discharge has been explored. The powder has been prepared from a nickel sulfate-containing electrolyte using soluble nickel anodes at a cathodic current density in the range of 11000–19000 A/m2, a voltage on the spark gap of 12–16 kV, and a pulse repetition frequency of 0.5 Hz. The effect of various factors on the synthesis of the powder has been studied and the optimum conditions for its preparation have been found using mathematical experiment design. The size distribution of particles has been determined with a particle size analyzer. The BET specific surface area of the powder has been measured to be 11.7 ± 2.1 m2/g.

The current–voltage characteristics of high-voltage spark discharge over a dielectric surface in vacuum

Investigation of temporal dependences of the voltage and current of high-voltage spark discharge over a dielectric surface in vacuum has shown that, in the presence of a longitudinal magnetic field, delay of the leading edge of the pulse-breakdown voltage takes place and the current, in turn, is converted from a well-defined impulse into alternating oscillations. Deceleration of the breakdown process in the presence of a low-current discharge that precedes the spark has been observed.

Effects of plate electrode materials on hydrogen production by pulsed discharge in ethanol solution

Hydrogen production from an ethanol solution by pulsed high voltage spark discharge was optimized by varying the material of plate electrode. It is the first time that metal work function has been used in hydrogen production by plasma reforming. With low work function metal plate electrode, both energy efficiency and hydrogen yield can be increased. The flow rate and the percentage concentration of hydrogen were achieved 1.3L/min and 75% respectively while discharging with zinc plate electrode for hydrogen production, which is much better than traditional stainless steel electrodes at the same conditions. The analysis of emission spectra was also accomplished in this work. All the intensity of existing spectral lines showed a decline with higher work function metal as plate electrode, and H may be the key to the process of hydrogen production. Additionally, electron temperature and density were also estimated. Both of which were increased with lower work function metal plate electrodes. The electron temperature and density can reach 24,000K, 7.5×1018cm−3 respectively.

Characteristics of hydrogen produced by pulsed discharge in ethanol solution

Hydrogen production from ethanol solution by pulsed high voltage spark discharge was investigated in this work. It is the first time that pulsed high voltage spark discharge in ethanol solution has been used for hydrogen production in the existing documents. A needle–plate reactor for on-board hydrogen production was also designed, which is small-scale and portable for automobiles. By optimizing the reaction conditions, the flow rate of hydrogen can reach 422mL/min at peak voltage=30kV, discharge frequency=30Hz, electrode distance=15mm, initial ethanol concentration=50%. It was also found that energy consumption of this method is about 1.69kWh/m3, which is better than most existing methods.

Real-time monitoring system for improving corona electrostatic separation in the process of recovering waste printed circuit boards.

Although corona electrostatic separation is successfully used in recycling waste printed circuit boards in industrial applications, there are problems that cannot be resolved completely, such as nonmetal particle aggregation and spark discharge. Both of these problems damage the process of separation and are not easy to identify during the process of separation in industrial applications. This paper provides a systematic study on a real-time monitoring system. Weight monitoring systems were established to continuously monitor the separation process. A Virtual Instrumentation program written by LabVIEW was utilized to sample and analyse the mass increment of the middling product. It includes four modules: historical data storage, steady-state analysis, data computing and alarm. Three kinds of operating conditions were used to verify the applicability of the monitoring system. It was found that the system achieved the goal of monitoring during the separation process and realized the function of real-time analysis of the received data. The system also gave comprehensible feedback on the accidents of material blockages in the feed inlet and high-voltage spark discharge. With the warning function of the alarm system, the whole monitoring system could save the human cost and help the new technology to be more easily applied in industry.

Measurement of effective blast energy for direct initiation of spherical gaseous detonations from high-voltage spark discharge

In this study, effective energy from spark discharge for direct blast initiation of spherical gaseous detonations is investigated. In the experiment, direct initiation of detonation is achieved via a spark discharge from a high-voltage and low-inductance capacitor bank and the spark energy is estimated from the analysis of the current output. To determine the blast wave energy from the powerful spark, the time-of-arrival of the blast wave in air is measured at different radii using a piezoelectric pressure transducer. Good agreement is found in the scaled blast trajectories, i.e., scaled time c o·t/R o where c o is the ambient sound speed, as a function of blast radius R s/R o between the numerical simulation of a spherical blast wave from a point energy source and the experimental results where the explosion length scale R o is computed using the equivalent spark energy from the first 1/4 current discharge cycle. Alternatively, by fitting the experimental trajectories data, the blast energy estimated from the numerical simulation appears also in good agreement with that obtained experimentally using the 1/4 cycle criterion. Using the 1/4 cycle of spark discharge for the effective energy, direct initiation experiments of spherical gaseous detonations are carried out to determine the critical initiation energy in C2H2–2.5O2 mixtures with 70 and 0% argon dilution. The experimental results obtained from the 1/4 cycle of spark discharge agree well with the prediction from two initiation models, namely, the Lee’s surface energy model and a simplified work done model. The main source of discrepancy in the comparison can be explained by the uncertainty of cell size measurement which is needed for both the semi-empirical models.

An investigation of spark discharge parameters for material processing with high power ultrasound

High power ultrasound (HPU) generated using pulsed-power techniques provides an alternative method for treating ores and minerals prior to extraction processes and for the comminution of waste materials as part of a recycling process. In an earlier publication [Wilson, M.P., Balmer, L., Given, M.J., MacGregor, S.J., Mackersie, J.W., Timoshkin, I.V., 2006. Application of electric spark generated high power ultrasound to recover ferrous and non-ferrous metals from slag waste. Minerals Engineering 19, 491–499], preliminary results using the HPU technique to treat stainless steel slag and waste bottle glass were reported. This paper describes further work performed on stainless steel slag to determine the likely energy costs associated with HPU processing. In industrial applications of HPU it is important to optimise the parameters of the high-voltage (HV) spark discharge causing the shock wave in the working liquid to maximise the efficiency of the treatment. However, because of the high intensity of the shock wave it is difficult to measure its output close to the HPU source. Experiments have therefore been performed using Pinducer sensors to measure the pressure waves produced by the source at distances relatively far from the spark discharge. These measurements made in the far field have been correlated with the electrical energy provided to the discharge and treatment rates for stainless steel slag and bottle glass obtained under identical conditions.

Hydrodynamic modelling of transient cavities in fluids generated by high voltage spark discharges

Application of a voltage pulse having a rise time of tens of nanoseconds to electrodes immersed in water results in streamer development and the formation of a highly conductive plasma channel between the electrodes. The electrical resistance of such channels decreases rapidly from a few ohms to a few tens of milliohms due to Joule heating resulting from the high current which flows through the plasma. The dynamics of the plasma resistance depend on the parameters of the discharge circuit and the medium in which the discharge takes place. The resistance of the channel reaches a minimum value approximately at the moment of the peak current for under-damped current oscillations. During the resistance collapse, the pressure inside the channel rises to several GPa, causing a rapid expansion of the channel which forms a cavity in the liquid resulting in a high power ultrasound pulse. The cavity expands to a maximum size which is dependent on the circuit driving the discharge and the properties of the plasma discharge channel. The cavity then collapses producing a second acoustic pulse. In this paper the dynamic resistance of the spark channel is described using a phenomenological model based on the plasma channel energy balance equation used by Braginskii. The model which links the hydrodynamic characteristics of the channel and the resulting cavity with the parameters of the electric driving circuit allows the development of the plasma channel and cavity to be predicted. The peak high-power ultrasound (HPU) pressures calculated using this approach are compared with the pressure values estimated by an analytical model which uses a constant value of the spark channel resistance derived from experimental data. Comparisons are also made with direct measurements of HPU output made using a Pinducer sensor. Although the model is based on a phenomenological description of the plasma channel dynamics and its resistance and requires the value of the spark constant, the results obtained using this approach provide a reasonable agreement with experimental measurements and could therefore be used for the estimation of HPU pulse characteristics in practical applications of spark discharges in water.

Electric fields in compact clusters of parallel current channels

The electric field in compact clusters of parallel current channels is calculated in the model of a bundle of long parallel cylindrical conductors. It is shown that, because of the mutual neutralization of the fields of individual microchannels, the maximal radial electric field in a compact cluster of microchannels can be lower than the critical field needed for ionization multiplication and channel expansion. This explains the existence of groups of microchannels (less than 10 μm in radius) in high-voltage nanosecond diffuse and spark discharges.

The lithotriptor and its potential use in the revision of total hip arthroplasty.

The lithotriptor and its potential use in the revision of total hip arthroplasty.

Raman scattering study of photoluminescent spark-processed porous InP

Raman scattering has been used to study porous InP (001) samples prepared by the application of high voltage spark discharges in air and argon atmospheres. For photoluminescent material, Raman scattering as well as Normaski microscopy of a transversally cut sample, (011) face, show the existence of two very distinct zones, that lie at different depths: a superficial luminescent region constituted mostly by In 2O 3 and InPO 4 oxides, and a second adjacent deeper zone formed by damaged InP. These results highlight the role that the oxidation plays in this material as source of the visible luminescence that the material emits when excited with UV radiation. The deepest region shows InP-like vibrational behavior with broad longitudinal optical (LO) and transversal optical (TO) phonon bands. A fit of the observed lineshapes of the TO and LO modes using the spatial correlation model provides an estimate of the size of the crystalline regions ( L∼30 Å).

Dependence on the atmosphere of preparation of the luminescence of spark processed porous GaAs

We report on the preparation of photoluminescent porous GaAs by the application of high voltage spark discharges in atmospheres of pure oxygen, pure nitrogen, and in mixed N2:O2 ratios of 4:1 and 1:4. The spark-processed porous (spp) samples were characterized by the observation of their visible photoluminescence (PL) when illuminated with UV monochromatic radiation. Some differences are observed in the initial PL spectra of the spp-GaAs according to the atmosphere of preparation under similar sparking and time conditions. The PL consists of two dominant bands, a yellow-green band between ∼2.2 and 2.6 eV and a blue-violet band, centered at 3.1 eV. Comparison with Raman and PL results from As2O3 and As2O5 indicates that the PL in the spp-GaAs is produced by the formation of these compounds by exposure to oxygen during the preparation. This is reinforced by energy dispersive x-ray spectroscopy measurements that indicate that the spp-GaAs is always oxidized, even when prepared under a nitrogen flow. The blue-UV emission at 3.1 eV suggests that we cannot rule out confinement as a contributing mechanism for this PL. Raman spectra indicate that for samples prepared in pure nitrogen, the resulting material consists of amorphous As and GaAs, and the cubic form of As2O3, arsenolite. PL and Raman indicate that there exists an increasing degree of amorphization of the resultant material with the introduction of nitrogen in the preparation atmosphere.