The use of high voltage (HV) electrodes in vacuum is commonplace in physicslaboratories. In such systems, it has long been known that electron emissionfrom an HV cathode can lead to bremsstrahlung X-rays; indeed, this is the basicprinciple behind the operation of standard X-ray sources. However, inlaboratory setups where X-ray production is not the goal and no electron sourceis deliberately introduced, field-emitted electrons accelerated by HV canproduce X-rays as an unintended hazardous byproduct. Both the level of hazardand the safe operating regimes for HV vacuum electrode systems are not widelyappreciated, at least in university laboratories. A reinforced awareness of theradiation hazards associated with vacuum HV setups would be beneficial. Wepresent a case study of a HV vacuum electrode device operated in a universityatomic physics laboratory. We describe the characterisation of the observedX-ray radiation, its relation to the observed leakage current in the device,the steps taken to contain and mitigate the radiation hazard, and suggestsafety guidelines.
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