减压直流非转移弧等离子体射流速度的静电探针测量

组建了一套利用静电探针诊断技术测量减压直流非转移弧等离子体射流速度的实验系统。对以纯氩为工质的等离子体，在气流量1．25×10^-1kg/s、弧电流80A、真空室压力165Pa的条件下，测量了射流的速度及其分布。结果表明射流在发生器出口处中心最高速度约为1200m／s，在半径20mm处减小到635m／s。沿射流轴线方向的速度梯度约为10（ms^-1）／mm。射流速度随着弧电流增加而缓慢单调增加；当真空室压力从165Pa提高到2kPa时，发生器出口轴线上的射流速度从1200m／s降至570m／s。

Flow Velocity Measurement in a Non-Transferred DC Arc Plasma-Jet by Using Electrostatic Probes

An electrostatic probe diagnostics system was established to measure the flow velocity in a non-transferred DC arc plasma-jet. The velocity distributions in an argon plasma jet at feeding-gas flow rate of 1.25 × 10^-4 kg/s and arc current of 80 A were obtained when the chamber pressure was at 165 Pa. Results show that the central maximum velocity of the plasma jet-flow at the torch exit is about 1 200 m/s, the flow velocity reduces to 635m/s at the radial distance of 20 mm, and the axial velocity gradient of the jet flow is about 10 （ms^-1）/mm; A slow monotonic increasing of the flow velocity was observed with the increasing arc current ; At elevated pressures up to 2 kPa, the central velocity of the plasma jet flow at the torch exit reduces to 570 m/s.