Transmission Line Corona and X-Rays

Recently the issue has resurfaced that corona on transmission lines may create x-rays. A letter to IEEE Spectrum and legal pleadings filed in a transmission line routing application have raised this subject. There is little published information and limited measurements have not detected x-rays from transmission lines. This paper presents an analysis using well-established physical principles. A practical lower bound of x-rays is at least 2,000 electron-volts (2 keV) due to almost immediate absorption by air of lower energy x-rays. However, the electrical discharges of coronal activity on transmission lines can produce electron energies on the order of about 1–10 eV. This is sufficient for production of visible light but is orders of magnitude below electron energies necessary for production of x-rays above 2 keV. All potential mechanisms for production of x-rays by transmission line corona were evaluated and none could produce any detectable amounts of x-rays of the required energy.