Jim, For practical purposes, what John says below is true. However, magnetrons are a special case as the emissions are roughly equivalent to those for double the voltage, hence your 8kV will give rise to the same emissions as other types of tube operating at 16kV, which puts you into the region that John suggests. Any vacuum tube operating at >5kV will give rise to some X-ray emissions, but they are unlikely to reach hazardous level until you get to >15kV. The design of the particular tube will have an effect on the level of emissions, so there is no one rule for all. You really need to consult the Ionising Radiation Regulations (S.I. 1999 No. 3232) for both accidental and occupational exposure levels. The level you state reflects these regulations, but in an environment where such emissions are quite likely (vacuum tube manufacture and test) a lower limit would be prudent. As a similar manufacturer, we work to a level of 2.5 micro Sieverts per hour. In any area where there could be a risk of accidental exposure (to persons not aware of the risks) a level of around one tenth of the occupational exposure limit is advised. As far as measuring instruments are concerned, you could start with Berthold, or just put 'radiation survey meter' into a web search engine (www.alltheweb.com gave me 500 hits on this search term).
Best regards Neil R. Barker CEng MIEE FSEE MIEEE Manager Compliance Engineering e2v technologies (uk) ltd 106 Waterhouse Lane Chelmsford Essex CM1 2QU UK Tel: (+44) 1245 453616 Fax: (+44) 1245 453410 Mob: (+44) 7801 723735 From: [email protected] [mailto:[email protected]] Sent: 06 March 2006 12:56 To: Speakman, Jim Cc: '[email protected]' Subject: Re: Ionising Radiation (X-radiation) from High Voltage Sources Jim In my own experience you don't normally get measureaX-ray emissions until the voltage gets to around 15-20kV. Regards John Allen > Am interested in the possibility of adventitious output of X-Radiation > from > high voltage sources, in this particular instance, magnetrons operating at > around 8 kV. > > Two questions: > > 1. Does anybody know whether there is a level of x-radiation produced at > these sorts of power levels that could conceivably generate a health > hazard > (.e.g, in excess of 7.5 micro Sieverts/hour at about 0.5 m from the > source) > ???? > > 2. Can anybody identify an appropriate device with which to survey and > accurately measure the output of x-radiation from such sources ???? > > > Many thanks, in anticipation > > Jim > > Jim Speakman > (Design Safety Representative (Crawley)) > > Thales UK Limited > Aerospace Division > Manor Royal > Crawley > RH10 9PZ > > Tel: 01293 644911 (Direct Dial) > 07817 873496 (Cellular) > > mailto:[email protected] > - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
