Might I
preface this by saying i know little to
nil regarding
cathodes,
anodes, and
CRTs. Reading the
cathode and
anode nodes only confused me further, so I'm just going to jump in with an explanation of cathode poisoning and not touch the cathode/anode/
negative/
postive debacle with a
ten foot clown pole.
What is often called cathode poisoning happens when residual gasses in a cathode-ray tube get ionized and attracted to the electrically negative cathode. This can cause the cathode to stop emitting electrons by chemically reacting with the barium and strontium oxides which coat the cathodes of most tubes. These oxides emit electrons at a much lower temperature than most cathode materials. As the cathode becomes more oxidized it becomes 'poisoned', and the electron emission goes down until there is too little to support proper operation; e.g. your TV stops working. Blame it on those damn oxides.
Why the oxidated cathode emitting electrons at lower temperatures correlates with emitting less electrons, I'm not sure. Strangely enough, I never took a high school physics class.
From what I have read on the 'net regarding this subject, it seems that the term 'cathode poisoning' is used almost exclusively as slang among electronics hobbyists, so if there is a more scientifically accurate term for this phenomenon, please /msg me.
This writeup is released under the GFDL, version 1.2 or any later version.