Sciencemadness Discussion Board

X-Ray Generation

Gooferking Science - 15-1-2014 at 15:07

I just created a cathode ray tube! I am running it off of 10,000 volts half wave rectified. The vacuum source is a mini fridge compressor. Is there a chance of x-rays? I really don't want cancer....

you are ok

quantumchromodynamics - 15-1-2014 at 15:09

3-10kv keeps you out of x-ray land

Metacelsus - 15-1-2014 at 19:24

Cool! Are you running a cold cathode, Crookes style tube? I tried making a cathode ray tube a while ago, but my vacuum wasn't strong enough (it was from a single stage rotary vane pump). What pressure is the tube at?

QCD is right; you are not at risk from radiation.

Gooferking Science - 15-1-2014 at 20:12

Yes, it is a cold cathode ray tube. I have a piece of steel wire inside a glass tube that has been melted around it. The end of the tube is covered in aluminum foil with a small hole in it. The tube is inside a flask which is where I pull the vacuum. The two electrodes are charged and the ray starts up. The purple-blue ray coming from the hole in the foil is beautiful and is easily influenced by magnetic field. I am unsure on the pressure... I do know that dual stage rotary vane vacuum pumps capable of pulling 15 microns are available on eBay right now for a little over $100, which is a good deal.

vmelkon - 16-1-2014 at 15:23

Are you sure you didn't make a "neon" tube. You are probably just ionizing air.

Gooferking Science - 16-1-2014 at 15:44

The ray is influenced by magnetic fields so I am pretty sure it is a beam of electrons. Although part of the glow inside the electron gun is probably due to air ionization.

Cathode Ray Tube Experiments

Gooferking Science - 16-1-2014 at 16:19

What are some interesting experiments that can be performed with a cathode ray other than simple deflection with a magnet?

vmelkon - 16-1-2014 at 16:25

Quote: Originally posted by Gooferking Science  
The ray is influenced by magnetic fields so I am pretty sure it is a beam of electrons. Although part of the glow inside the electron gun is probably due to air ionization.


ionized gases are also effected by magnetic fields. Ions in a plasma tube move and thus, have their own magnetic fields.

neptunium - 16-1-2014 at 19:18

as long as you running a fridge compressor you will not pull anything else but pretty lights and oxygen and nitrogen ions.
10kv is also not enough to generate significant x ray capable of passing through the glass .

you will need to go deeper in vacuum to starts seing the blue green glow of electron beam (below about 5mm hg) further below the tube will become "hard" and no electric charge will pass through it especially with only 10Kv.

you definitely need a more powerful vacuum pump capable of reaching 10-3 mm Hg but 10Kv should be safe enough ...

some pictures would be nice!