# Fluorescent lamp X-ray emissions



## yuandrew (Sep 9, 2006)

I received an E-mail regarding an experiment I did with a compact fluorescent lamp and it stated that fluorescent lamps emit X-ray radiation.

Anyone know if it's true or not ? I'm thinking extreamly low levels if any. I tried searching on google but didn't come up with any answers.


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## Orbit (Sep 9, 2006)

*Re: Fluorescent lamp X-ray emission !?*

um....i'd be saying none..... keepin mind that even a specifically designed xray tube with huge tube voltages and comparativley huge currents convert only 1% of the energy to x-rays.

whilst there is stastically a possibility of x-ray production in and annode/cathode "spark" arrangement i'd be more worried about your mobile phone....


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## winny (Sep 9, 2006)

*Re: Fluorescent lamp X-ray emission !?*

+1 on what Orbit said.

Your average CRT monitor will probably output 100 times more X-ray radiation so you can always reply your mailer and ask what kind of monitor he/she is using, if they are worried about X-rays.


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## Orbit (Sep 9, 2006)

*Re: Fluorescent lamp X-ray emission !?*

even with CRT's most of the "x-rays" produced (which is less then sweet stuff all...you are more likely to die from radiation sickness induced from walking around too much out side in the sun... or taking too many intercontinental flights) are attenuated by the glass, mica, phoshpor envolope


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## mattheww50 (Sep 9, 2006)

*Re: Fluorescent lamp X-ray emission !?*

X-rays require energies of tens of thousands to hundreds of thousands of volts to generate them with any efficiency. When Photons get about a half million electron volts they are called gama rays. An X-ray used for dental X-ray runs at about 60-70,000 volts. Diagnostic X-ray and CT-Scan run on the order of 115,000 volts. Realistically until the X-ray energy gets to about 20,000 volts, they won't even get out of a simple glass envelope. The voltages in a fluorescent just aren't anywhere near high enough to generate measurable x-ray output. Even the ignition voltages is at most only a few thousand volts, so at startup it is possible for a fluorescent to generate very low energy X-rays at very low efficiency. The efficiency of the process at a few thousand volts is very very low. You really don't see appreciable X-ray output until you get to tens of thousands of volts, and even then most energy appears as heat until you get to hundreds of thousands of volts. There is reason X-ray tubes have a rotating anode (the anode is spun by a motor to prevent it from vaporizing. 115,000 volts at 25ma is about 2500 watts and it hits a target a few mm in diameter, and if you look at the anode at end of life, you can see that the the anode looks like a racetrack has been worn into it, the tungsen has been melted by the beam energy.

So the start voltage in Fluoroescent tube is high enough to produce a tiny amount of X-ray energy at very low energies at the Anode end. the energy is so low , they never escape the glass tube.

CRT's routinely have voltages on the order of 20,000 volts, are significant potential X-ray sources, in fact tubes have an X-ray warning. Generally the face plate on the CRT is either heavy glass, or glass with lead oxide. The face plate is sufficiently dense to absorb any X-rays produced out the front. The magnetic shield for the tube provides the X-ray shielding on the top,bottom, and sides.


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## Orbit (Sep 9, 2006)

*Re: Fluorescent lamp X-ray emission !?*

Correct!


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