Free Arc Research Articles

Free arc heating effect in double-layers hybrid arc source

Keyhole welding process is easily achieved with plasma arc heat source, but the welding speed for a stable keyhole is hard to increase because of the low-level heat input. Higher welding current will increase the heat input, but the induced heavy arc pressure acts to damage the keyhole stability. The narrow window of welding current creates limited usable range of heat input. Double-layers hybrid arc heat source is developed by compositing an outer layer of free arc into the center plasma arc jet. Set the plasma arc current level to create enough arc pressure to open a keyhole, the outer layer arc is used to control additional heat power into the weld pool but has little effect to influence the arc pressure. The free arc heating effect in the hybrid arc is figured out: (1) much faster welding speed can be achieved, it increases from 3 mm/s to 4.75 mm/s after additional 80 A/80 A free arcs are used, and (2) the increase of welding speed is highly related to the total heat input in the hybrid arc and is unrelated to the free arc number; (3) the calculated efficiency factor is selected as 0.75 for the added free arc. The developed hybrid arc is proved to be a robust method to increase the manufacturing efficiency.

Carrier-Gas free arc igniter microplasma optical emission spectrometry for the determination of arsenic in soil

Rapid on-site assessment of arsenic contamination in soils is crucial for environmental protection and human health. In order to build an effective and affordable device for the determination of arsenic, the use of carrier gas supplies and high power energy consumption largely limit the miniaturization of microplasma-based optical emission spectrometry (OES). An arc igniter microplasma (AIM) can be powered by a low DC power supply and operated in the atmosphere of air without gas infusion, which is beneficial to construct a carrier-gas free and low power supply setup. Hydride generation (HG) can improve sample transport efficiency and reduce matrix effects, but the generated by-product hydrogen has not been explored as a sole working gas for plasma excitation. In this work, a hydride generation arc igniter microplasma optical emission spectrometer (HG-AIM-OES) was fabricated for detecting arsenic in soils. H2 derived from HG was served as a working gas to transport AsH3 to excite, eliminating the use of a carrier gas unit. Under the optimized operating conditions, the limit of detection (LOD) for arsenic was 164 μg/L (the analytical line at 234.98 nm), and good linearity of the method was achieved in the range of 0.5–20 mg/L with a precision of 3.14 % (the concentration of arsenic at 1 mg/L). In addition, the influence of H2 on AIM physical properties was carefully studied in the air and Ar discharge atmospheres. The accuracy of the proposed device was validated by the analysis of certified reference materials (CRMs) and a real soil sample, resulting in good agreement with the obtained results by air and Ar as working gas. This HG-AIM-OES system provides a miniaturized, carrier gas-free and low power consuming tool for monitoring and assessment of arsenic-contaminated soils.

Keyhole Welding with Hybrid Plasma-Free Arc Source

Improving the keyhole welding process window is challenging work because the force and thermal state in the weld pool are hard to control. A hybrid plasma-free arc source was developed based on a plasma arc torch, sided tungsten was added close to the constraint orifice to form a free arc, and hybrid arcs formed after the free arc was fully absorbed into the constraint arc. In such a one-anode, twocathode hybrid arc system, the added free arc acts in an assistant role to adjust arc heat output without influencing the arc pressure peak, and the constraint arc acts as the guiding arc to control the arc pressure and slightly incline to the free arc side. Bead-on welding experiments were done to test keyhole welding process behavior with the hybrid arc source, including arc column, keyhole state, weld surface performance, and melting state in the weld pool. Results showed that (1) the hybrid arc can enlarge the stable keyhole welding process window in aspects of welding current and welding speed, and a more-obvious improving effect is obtained with the leading-sided tungsten; (2) the hybrid arc with the rear-sided tungsten has a smooth front weld surface; (3) the increased heat will enlarge the weld cross-section area with no obvious influence to the backside weld width; and (4) the leading keyhole wall is related to the outer tungsten position. The research gives a new method for improving keyhole welding stability.

Keyhole Welding with Hybrid Plasma-Free Arc Source

Improving the keyhole welding process window is challenging work because the force and thermal state in the weld pool are hard to control. A hybrid plasma-free arc source was developed based on a plasma arc torch, sided tungsten was added close to the constraint orifice to form a free arc, and hybrid arcs formed after the free arc was fully absorbed into the constraint arc. In such a one-anode, twocathode hybrid arc system, the added free arc acts in an assistant role to adjust arc heat output without influencing the arc pressure peak, and the constraint arc acts as the guiding arc to control the arc pressure and slightly incline to the free arc side. Bead-on welding experiments were done to test keyhole welding process behavior with the hybrid arc source, including arc column, keyhole state, weld surface performance, and melting state in the weld pool. Results showed that (1) the hybrid arc can enlarge the stable keyhole welding process window in aspects of welding current and welding speed, and a more-obvious improving effect is obtained with the leading-sided tungsten; (2) the hybrid arc with the rear-sided tungsten has a smooth front weld surface; (3) the increased heat will enlarge the weld cross-section area with no obvious influence to the backside weld width; and (4) the leading keyhole wall is related to the outer tungsten position. The research gives a new method for improving keyhole welding stability.

Numerical analysis of arc physics and energy transfer under circumferential gas constraint effect

Energy dispersion and easy instability associated with arcs, the traditional metal processing heat source, restrict its development and application in the modern high-precision welding and additive manufacturing. This work aims to study the characteristics of a novel arc under circumferential gas constraint effect which can improve the arc stability and processing accuracy. A magnetohydrodynamics model was established to calculate the arc physics and heat transfer, considering the electron emission characteristics of tungsten and the effect of metal vapor. It indicates that the annular flexible constrained gas flow can significantly increase the physical characteristics such as arc temperature, plasma flow velocity and current density compared with traditional free arc which is named GTA. The arc heat generation increasement of the novel arc makes the heat transfer from arc to base metal higher than that of GTA. The additional annular gas flow inhibits the diffusion of metal vapor, stabilizing the arc and protecting the tungsten electrode from contamination. However, as the arc length decreases, eddy of arc plasma flow appears inside the arc, which can cause metal vapor to contaminate the tungsten. It's found that this novel gas flow constrained arc needs to be applied with a small current when welding with small arc length to avoid the eddy. Finally, the accuracy of the calculation model is verified by experimental detection of arc temperature.

Preparation of Pt/CNT catalyst with high dispersion structure via plasma jet

A plasma jet (a high temperature jet formed by blowing a free arc through high pressure air) method based on free arc was carried out to disperse carbon nanotubes (CNTs) in gas phase while generating Pt nanoparticles (Pt-NPs) on them at the same time. The plasma jet is generated through the discharge between the cathode composed of CNTs, PtCl4 and DI water and the anode with a hole. Plasma jet prepares the Pt/CNT catalyst by directly spraying. The CNT carrier in the catalyst have good dispersion by SEM images. The mean size of Pt-NPs estimated by TEM images is 3.41 nm with the plasma jet method and about 4.77 nm with the commercial Pt/C respectively. It was showed that the bulk of Pt-NPs produced by plasma jet is in metal state in the analysis of XPS measurements. Compared with Pt/C, Pt/CNT have roughly equal catalytic activity and higher durability by cyclic voltammetry measurements. Based on these properties, the plasma injection method solves the problems of carrier dispersion and metal particle preparation at the same time, which greatly simplifies the catalyst preparation process.

Relatively pointwise recurrence on local dendrites

Let X be a local dendrite and let f : X → X be a continuous map. Denote by P ( f ) and R ( f ) the sets of periodic and recurrent points of f, respectively. We say that f is relatively pointwise recurrent if R ( f ) ¯ = X . We show that, if X is almost meshed (i.e the union of the interior of all free arcs is dense in X), then f is relatively pointwise recurrent if and only if either f is topologically conjugate to an irrational rotation on the circle or it has a dense set of periodic points.

Welding process with hybrid arc by compositing two free arcs into constraint arc

Controlling heat output and force in the arc source is important to improve the keyhole stability during welding. In this study, a double-layer hybrid arc torch was developed by adding two outer tungsten electrodes symmetrically to the orifice in the plasma arc torch. Two free arcs forming from the two outer tungsten tips are absorbed into the center constraint arc to form a hybrid arc. The arc pressure of the hybrid arc was measured, and welding experiments were carried out to test the application possibility in the keyhole welding process. It was found that: the arc pressure of the hybrid arc with two free arcs is symmetrical. The additional heat input provided by free arcs can be transferred into the keyhole bottom, and a lower constraint arc current is needed to form a stable fully penetrated keyhole. With the left-right arranged outer tungsten electrodes, arc heat is easier to be deposited into the keyhole bottom, and less sum of arc current is needed to form a fully penetrated keyhole. With the leading-rear arranged outer tungsten electrodes, the reflected arc will bridge the weld pool and the rear tungsten, and the coupling state between the free arc and the constraint arc is disturbed. When the constraint arc current is 115A and the free arc current is 40A, a fully penetrated keyhole can be formed with the left-right arranged outer tungsten electrodes but cannot be formed with the leading-rear arranged outer tungsten electrodes. The proposed hybrid arc system has advantages over the previous model in terms of a wider range of usable arc current and symmetrically distributed arc.

Free Arc Disperses-Sprays Carbon Nanotubes and Silicon Carbide, Preparing Thermal Silicone Grease

Thermal conductivity grease (TSG) is an important interface material for electronic devices’ heat dissipation. A continuous free-arc dispersion-spraying method of carbon nanotubes (CNTs) and nanocrystalline silicon carbide (SiC) for the preparation of TSG is reported. CNTs and SiC are dispersed and mixed by a free arc and are sprayed on the silicone oil surface (carried by the conveyor belt). Then, the silicon oil is separated from the conveyor belt, and the TSG composite (TSG-E) with highly dispersed CNTs@SiC is prepared. In this work, TSG-E has a CNTs@SiC network with CNTs as the frame and SiC as the node. Compared with untreated (TSG-N), grind (TSG-G), and ultrasonic (TSG-U) dispersion methods, TSG-E has better thermal conductivity (λ) and resistivity. CNTs@SiC network of the TSG-E series affects λ, the effect follows the thermal conductivity network theory and has a sudden change (greatly decreased) from TSG-E0.2 to TSG-E0.3. Besides, the sudden change of thermal stability for the TSG-E series is consistent with the change of λ.

Transcatheter Left Ventricular Restoration in Patients With Heart Failure

BackgroundLeft ventricular (LV) volume reshaping reduces myocardial wall stress and may induce reverse remodeling in patients with heart failure with reduced ejection fraction. The AccuCinch Transcatheter Left Ventricular Restoration system consists of a series of anchors connected by a cable implanted along the LV base that is cinched to the basal free wall radius. We evaluated the echocardiographic and clinical outcomes following transcatheter left ventricular restoration. Methods and ResultsWe analyzed 51 heart failure patients with a left ventricular ejection fraction between 20% and 40%, with no more than 2+ mitral regurgitation treated with optimal medical therapy, who subsequently underwent transcatheter left ventricular restoration. Serial echocardiograms, Kansas City Cardiomyopathy Questionnaire scores, and 6-minute walk test distances were measured at baseline through 12 months. Primary analysis end point was change in end-diastolic volume at 12 months compared with baseline. Patients (n = 51) were predominantly male (86%) with a mean age of 56.3 ± 13.1 years. Fluoroscopy showed LV free wall radius decreased by a median of 9.2 mm amounting to a 29.6% decrease in the free wall arc length. At 12 months, the LV end-diastolic volume decreased by 33.6 ± 34.8 mL (P < .01), with comparable decreases in the LV end-systolic volume. These decreases were associated with significant improvements in the overall Kansas City Cardiomyopathy Questionnaire score (16.4 ± 18.7 points; P < .01) and 6-minute hall walk test distance (45.9 ± 83.9 m; P < .01). There were no periprocedural deaths; through the 1-year follow-up, 1 patient died (day 280) and 1 patient received a left ventricular assist device (day 13). ConclusionsIn patients with heart failure with reduced ejection fraction without significant mitral regurgitation receiving optimal medical therapy, the AccuCinch System resulted in decreases of LV volume, as well as improved quality of life and exercise endurance. A randomized trial is ongoing (NCT04331769).

Two-Steps Method to Prepare Multilayer Sandwich Structure Carbon Fiber Composite with Thermal and Electrical Anisotropy and Electromagnetic Interference Shielding.

Carbon fiber (CF) composites performance enhancement is a research hotspot at present. In this work, first, a sandwich structure composite, CF@(carbon nanotube/Fe3O4)/epoxy (CF@(CNT/Fe3O4)/EP), is prepared by the free arc dispersion-CFs surface spraying-rolling process method, herein, CFs in the middle layer and (CNT/Fe3O4)/EP as top and substrate layer. Then, CF@(CNT/Fe3O4)/EP (on both sides) and CFs (in the middle) are overlapped by structure design, forming a multilayer CF@(CNT/Fe3O4)/EP-CFs composite with a CFs core sheath. A small amount of CNT/Fe3O4 is consumed, (CNT/Fe3O4)/EP and CFs core sheath realize thermal and electrical anisotropy and directional enhancement, and multilayer sandwich structure makes the electromagnetic interference (EMI) shielding performance better strengthened by multiple absorption-reflection/penetration-reabsorption. From CF-0 to CF-8, CNT/Fe3O4 content only increases by 0.045 wt%, axial thermal conductivity (λ‖) increases from 0.59 W/(m·K) to 1.1 W/(m·K), growth rate is 86%, radial thermal conductivity (λ⟂) only increases by 0.05 W/(m·K), the maximum λ‖/λ⟂ is 2.9, axial electrical conductivity (σ‖) increases from 6.2 S/cm to 7.7 S/cm, growth rate is 24%, radial electrical conductivity (σ⟂) only increases by 0.7 × 10-4 S/cm, the total EMI shielding effectiveness (EMI SET) increases by 196%, from 10.3 dB to 30.5 dB. This provides a new idea for enhancing CFs composite properties.

Low temperature characteristics of FBG with free arc shape for low temperature monitoring

It is important to monitor the iced condition for operating wind turbine blades. However, most sensors are difficult to be used in this quite cold and lightweight environment. Although the fiber bragg grating (FBG) is a good candidate for the case. With the change of the temperature, the thermal expansion coefficient and thermo-optical coeffecient of FBG material will affect the accuracy of characteristics of FBG sensor. Aiming at the application of fiber optic sensor in low temperature environment and ultrathin requirement, the low temperature characteristics of FBG sensor with free arc shape package has been studied. The low temperature calibration experiments of two packaged FBG samples are tested from -35°C ~20°C in a constant temperature freezer with alcohol tank. The effects of low temperature characteristics of two FBGs packaged with free straight and arc shape tubes are compared. The results show that arc shape can effectively reduce the repeatability error and improve its accuracy due to providing possible low temperature contracting of the optical fibers. Flat arc shape makes it possible to package ultrathin FBG temperature sensor.

Mechanical Characterization of Ultra-Thin, Flexible Glass Substrates for RF Applications

Glass has been shown to be a capable core substrate material for high-frequency applications. In this article, we examine the capabilities of ultra-thin glass as a material that can be used for high-frequency flexible applications. The two stack-ups discussed in the work presented are 60 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> in total thickness with a core glass substrate (Schott AF32) of 30 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> thickness. One stack-up uses 15 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> JSR GT-N01 as a buildup dielectric on each side of the glass and the other uses 15 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> Taiyo Ink photo imageable dielectric (PID). Both stack-ups have been characterized to 110 GHz and have shown to have comparable performance to materials used in this frequency range. This work then focuses on the mechanical characterization of these stack-ups using free arc bending. The free arc bending tests show that both ultra-thin glass stack-ups are suitable for bending applications as the tested samples can bend to a panel separation below 33% of the sample’s total length. This article concludes that the ultra-thin glass stack-ups are suitable for high-frequency flexible applications because the electrical performance is comparable to other high-frequency rigid materials while exhibiting their flexible capabilities.

A patient-specific image-based approach to estimate pulmonary artery stiffness based on vessel constitutive model.

An accurate non-invasive evaluation of the mechanical properties of the vessel wall is important for a variety of screening protocols and surgical treatments. In this work, we focused on a sectionof the Pulmonary Artery (PA), and developed a patient-specific approach to estimate its stiffness in terms of the Young's modulus along the circumferential direction (E). First, we developed a patient-specific semi-automatic approach to estimate its expected value and standard deviation. To this end, pressure-length curves were derived from magnetic resonance images acquired during the cardiac cycle and information on vessel pressure obtained by catheterization. Then, the estimates of E were derived through a maximum likelihood estimation approach based on a vessel constitutive law. In particular, we analyzed the entire PA boundary and an arc free from surrounding organs. Second, we applied the approach to the study of pulmonary endarterectomy (PEA) for the treatment of chronic thromboembolic pulmonary hypertension (CTEPH). We observed a decrease in the circumferential E after PEA for the whole boundary, while no clear trend was observed for the free arc. The low standard deviations associated with the estimates showed high accuracy when considering the entire boundary, while greater variability was observed for the free arc, which was however limited. Finally, reliable hysteretic behavior was obtained from the reconstructed pressure-length curves.

A novel arc plasma generating method by coaxial hybrid a ring arc to constraint arc: Principle and progress

Controlling of arc pressure in an arcing system is a critical and basic issue for welding application. A novel arcing torch is proposed to improve the controllability, a ring tungsten cathode is coaxial embedded into the water-cooling copper plasma arc nozzle. In the arcing process, the arc current flows into a single arc after it heats the anode and breaks into two branches to earth into the two separated cathodes: the center path works as the ordinary plasma arc and flows into the inner tungsten, the outer bypass free arc surrounds the center arc and flows into the ring tungsten. In this way, a coaxial hybrid arc forms based on a high-density plasma arc and a less-density ring free arc. Serial experiments were done to observe and measure the arc properties, including the arc column shape, arc pressure and anode state. It is observed that the outer arc can be fully absorbed into the inner arc to form a stable single hybrid arc. The hybrid arc properties are related to the two paths of arc current; the outer ring arc current has smaller pressure/current ratio than the central constraint plasma arc current. With such a version torch model, the employing current level of the ring arc is limited and lower than 40A to obtain stable hybrid arc. The results show the proposed arcing torch model is promising to control the output arc pressure with increased accuracy.

Oxide Free Wire Arc Sprayed Coatings—An Avenue to Enhanced Adhesive Tensile Strength

Conventionally, thermal spraying processes are almost exclusively carried out in an air atmosphere. This results in oxidation of the particles upon thermal spraying, and thus, the interfaces of the splats within the coating are oxidized as well. Hence, a full material bond strength cannot be established. To overcome this issue, a mixture of monosilane and nitrogen was employed in the present study as the atomising and environment gas. With this approach, an oxygen partial pressure corresponding to an extreme-high vacuum was established in the environment and oxide-free coatings could be realized. It is shown that the oxide-free particles have an improved substrate wetting behaviour, which drastically increases the adhesive tensile strength of the wire arc sprayed copper coatings. Moreover, the altered deposition conditions also led to a significant reduction of the coating porosity.

Computer Intelligent Numerical Simulation of TIG Welding Using Platy Tungsten Electrode

In order to reveal the law of arc plasma flow and heat transfer in the process of flat tungsten electrode TIG welding as auxiliary heat source for hardfacing of cast iron surface. According to the free burning TIG arc using platy tungsten electrode, A three dimensional (3D) model for tungsten inert gas welding using platy tungsten electrode has been developed. The whole region of platy tungsten TIG arc, namely, platy tungsten cathode, arc plasma and anode surface is treated in a unified numerical model. By using fluent software to do the second development of equations source and solve these equations, the distribution of temperature, velocity and current density are obtained. The simulation results show that the current of flat tungsten electrode is more dispersed, and the heat generation of arc is more dispersed, which leads to the decrease of arc temperature; The current density on the cathode is much higher than that on the anode.

Is it advantageous to use deep inspiration breath hold (DIBH) over free breathing for FAST-Forward dose fractionation scheme in treating carcinoma of left-sided breast? A dosimetric study

Abstract Aim: To study the effect of deep inspiration breath hold (DIBH) on Fast-Forward trial for left-sided breast radiotherapy dosimetrically using tangential field-in-field (FiF), flattening filtered volumetric-modulated arc therapy (FF-VMAT) and flattening filter free volumetric-modulated arc therapy (FFF-VMAT) in comparison with free breathing (FB). Methods: Computed tomography images were acquired on 15 patients with carcinoma of left breast in FB and DIBH. Planning target volume (PTV) and organs at risk were contoured on both image sets. Dose of 26 Gy in five daily fractions was prescribed to PTV. FiF, FF-VMAT and FFF-VMAT plans were created in treatment planning system on both FB and DIBH. PTV V95%, V107%, D0·1 cc, CI and HI, heart V1·5 Gy, V7 Gy, lung left V8 Gy, monitor units (MU) and beam ON time were used for evaluation. Different technique analysis in same breathing condition and FB versus DIBH for same planning technique were performed. Results: Mean of all 15 patients was reported as mean ± 1 standard deviation. PTV V95% was 97·55 ± 0·10 (FiF), 95·75 ± 0·66 (FF-VMAT) and 96·15 ± 0·46 (FFF-VMAT) in FB while 97·34 ± 0·50 (FiF), 96·03 ± 0·71 (FF-VMAT) and 95·86 ± 0·63 (FFF-VMAT) in DIBH. Heart V7 Gy was 8·53 ± 4·26 (FiF), 8·86 ± 2·20 (FF-VMAT) and 9·27 ± 2·46 (FFF-VMAT) in FB while 6·30 ± 2·98 (FiF), 5·23 ± 2·20 (FF-VMAT) and 4·68 ± 2·01 (FFF-VMAT) in DIBH. p-value of heart V7 Gy between FB and DIBH was 0·278 (FiF), 0·009 (FF-VMAT) and 0·003 (FFF-VMAT). Beam ON time for FFF-VMAT was reduced by 65% (FF-VMAT) and 11% (FiF). Conclusion: Conformal dose to PTV was achieved better with VMAT plans. FFF-VMAT was delivered in less time compared to FF-VMAT and FiF for 26 Gy in five fractions. Heart dose can be significantly minimised with DIBH for VMAT plans.

Free breathing VMAT versus deep inspiration breath-hold 3D conformal radiation therapy for early stage left-sided breast cancer.

The purpose of the in silico study was to compare free breathing volumetric modulated arc therapy (VMAT) to standard deep inspiration breath‐hold (DIBH) three‐dimensional conformal radiotherapy (3DCRT) and determine whether the former is a viable option for elderly patients with left‐sided early stage breast cancer. Data from 22 patients with early‐stage left breast carcinoma requiring breast‐only radiation therapy were used for this planning study. The robustness of VMAT plans when using the free breathing method was compared to that of standard 3DCRT plans using the DIBH method. The endpoints for evaluation were the target dose coverage as well as doses to the organs‐at‐risk. The free breathing VMAT plans produced a significantly higher mean dose to the heart and right breast than the DIBH‐3DCRT plans. Free breathing VMAT plans resulted in significantly better target coverage than did 3DCRT using DIBH. The external volume that received more than 40 Gy was significantly smaller in the VMAT plans. Free breathing VMAT is a viable alternative to DIBH 3DCRT in elderly patients with a limited life expectancy and in subjects who are unable to perform DIBH. The choice of treatment should be individualized, and all relevant risks ought to be considered.

Hybrid a free arc into constraint-arc to improve arc pressure control behavior

Decoupling the arc pressure and heat output improves the controllability of the arc. In this study, an innovative torch was successfully developed for this purpose by adding an outer electrode under the orifice to a conventional plasma arc welding (PAW) torch. The arc rooting from the added electrode merges with the main/PAW arc forming a hybrid arc system with two cathodes and one anode. While the major arc is constrained, the added arc is allowing to change the anode heat while the pressure is still primarily controlled by the main arc. The coupling behavior was experimentally studied through analysis arc column image and arc pressure measurement. The results show that the added free arc formed by the outer electrode is fully absorbed and coupled into the constraint arc to form a single hybrid arc. The arc pressure peak value in the hybrid arc is little sensitive to outer free arc current compared with that by adjusting the center constraint arc current. Because the sided outer tungsten electrode is isolated to the center inner tungsten electrode and the cooper nozzle in the arcing torch system, the range of arc current applied by the outer tungsten electrode is large. The torch system provides a novel arc plasma generation method to improve the control precision in manufacturing process.