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.