Plasma Flow Measurement along Magnetic Field using Mach Probe

1)我们发现Chung提出的等离子体流量测量的想法存在一些困难，因为在托卡马克等实际等离子体装置中存在所谓的回收问题。在这项研究中，我们开发了一种新方法，成功地简化了这一问题。3)作为一种新的等离子体流估计方法，我们在马赫数探针前放置了一个分离器，利用包含等离子体粘度的MHD理论，我们发现两个饱和电流（即有分离器和没有分离器）的比值给出了等离子体流的马赫速度或马赫数。4)为了检验新方法的可靠性，我们采用了一种独立的方法测量流速，即两个剪切Alfven波的频散关系；一个是从上游发射，另一个是从下游发射。根据两种色散关系的差值，我们可以估计出实际的流速。结果表明，在实验误差和理论近似误差范围内，我们的马赫探头在测量流速方面是有用和可靠的。此外，应该强调的是，它还可以估计等离子体的粘度。

1) We found that there are some difficulties in the idea for plasma flow measurements proposed by Chung because of so-called recycling probrem which occurs in a real plasma device such as tokamak.2) In this study we have developed a new method, by which such a problem successfully reduced.3) As a new plasma flow estimation, we put a separator in front of a Mach probe : using a MHD theory including plasma viscosity, we found that the ratio of the two saturation currents, i.e. with and without the separator gives the Mach velocity or Mach number of the plasma flow.4) In order to check the reliability of our new method, we used an independent method to measure the flow velocity, i.e. the dispersion relation of the two shear Alfven waves ; one is launched from the upper stream side, and the other is from the down stream side. From the difference between two dispersion relations, we can estimate the real flow velocity.5) As a result, our Mach probe is found to be useful and reliable for measuring the flow velocity, within errors of experiment and of theoretical approximations. Moreover, it should be emphasized that it can also estimate the viscosity of the plasma.