Onset corona fields and electrical breakdown criteria
Onset corona fields and electrical breakdown criteria
复制标题
DOI：
10.1088/0022-3727/36/21/013
复制
发表时间：
2003-11
期刊：
影响因子：
--
通讯作者：
J. Lowke;F. D'alessandro
中科院分区：
文献类型：
--
作者：
J. Lowke;F. D'alessandro
从一般击穿判据出发，对球体和圆柱体在空气中产生电晕所需的电场进行了预测，α‘为净电离系数，r为半径，q为常数。结果表明，无论是导线还是点，对于正负电晕，在半径从0.01到20厘米的范围内，Q=104都能很好地符合实验结果。通过假定α‘与电离等于附着的临界场之差的线性变化，可以推导出电晕起始击穿电场作为球体半径的函数的解析式，该解析式类似于但不同于圆柱体或导线的Peek起始电晕公式。这些公式还给出了击穿电场与温度和压力的函数关系。对于汤森和Streamer击穿机制，Q值通常分别为3×104和108。因此，从导线和点的电晕起始场的实验值得出的Q值明显低于汤森击穿准则或Streamer击穿准则的预期。这表明，最有可能解释观察到的低Q值的碰撞过程是间接电离，例如通过激发分子之间的碰撞。
Predictions are made of the electric field necessary for the onset of corona in air for spheres and cylinders from the general breakdown criterion, ; α' is the net ionization coefficient, r is the radius and Q is a constant. It is found that Q = 104 gives a fair fit to experimental results for both wires and points, and for positive and negative corona, for radii varying from 0.01 to 20 cm. By assuming a linear variation of α' with the difference of the electric field from the critical field where ionization equals attachment, an analytic formula can be derived for the breakdown field for the onset of corona as a function of the radius of the sphere, which is similar to, but different from, Peek's formula for the onset of corona for cylinders or wires. The formulae also give the breakdown field as a function of temperature and pressure. For Townsend and Streamer breakdown mechanisms, values of Q are typically 3 × 104 and 108, respectively. Thus the value of Q derived from experimental values of the onset field for corona for both wires and points is significantly lower than would be expected from either the Townsend breakdown criterion or the Streamer breakdown criterion. It is suggested that the most likely collision process to explain the observed low value of Q is indirect ionization, for example by collisions between excited molecules.