Cathodic ray Emmisions. i need a plain expanation to a plain question.

[baroutologos]

Thank you Turbo for getting into trouble to enlighten me.


Actually i yesterday read about it, and this answered my initial question of how the electrons are escaping in a CRT the anode and hit the phosphor. Actually as you said, and CRT has its  phospor end tube connected to HV source so electrons are easily travel till there.


Thanks
***


One small explanation needed on Crookes tube. Why it works like that?


The metal cross image and the like.


In the beggining i can understand electrons hitting the cross and tube walls, but after a while since metal cross and tube walls reach a negative potential equal at least that of cathode, electrons should be deflected from cross (giving a blurry wall image?) and tube collisions should be minimum.


Unless the glass of the Crookes tube behaves as a feeble conductor and keeps a constant more positive than cathode's potential to all its distant from cathode places, cross included.


Thank you,
Barou

[Turbo]

There exists a certain threshold which is different or depends on the evacuation strength of the glass bulb.
In the Crookes tube, they deliberately use a residue gas in the bulb for collision/emission purposes.
But not important for now, what is important is that this threshold, for normal radio/tv tubes exists at 25.000 or 25 Kilovolt.
If the voltage on the tube exceeds this threshold the tube will start to radiate X-Rays.
You can find some videos of this on youtube.
Unlike your previous example with the CRT tube, where the electrons are pulled forward, in this X-Ray example the electrons DO have gained enough kinetic energy to travel freely.
They behave more like light or photons in this respect.
So you can see the shadow of the cross just as you would shine a light on it.
These high energetic particles have the ability to cause the phenomenon of secondary emission upon impact.
The Multipactor is most famous in utilizing this effect.
I believe this effect is also at work in a Fusor, and in the PAGD.
Maybe you will find some new leads there.
 

[baroutologos]

There exists a certain threshold which is different or depends on the evacuation strength of the glass bulb....
Unlike your previous example with the CRT tube, where the electrons are pulled forward, in this X-Ray example the electrons DO have gained enough kinetic energy to travel freely.
They behave more like light or photons in this respect.
So you can see the shadow of the cross just as you would shine a light on it....

Interesting! In other words, after a point of accelaration, electrons are losing their particle attraction/repulsion behaviour from electric fields and go straight no matterwhat like light?
Even if they go straight to a cathodic plate?


barou

[Turbo]

Interesting! In other words, after a point of accelaration, electrons are losing their particle attraction/repulsion behaviour from electric fields and go straight no matterwhat like light?
Even if they go straight to a cathodic plate?


barou

Not only do they go straight their kinetic energy is so high that they can go straight through and penetrate their target, which is why we are able to take X-Rays.
If you ever decide to experiment in this area make sure to shield yourself from these rays.
In the past i have done experiments and the day after my eyes would hurt, exactly the same as what they call 'welders eyes'  when you stare in the spark of welding for too long.
It simply burns the retina.
And its not without danger, these high energetic particles can knock electrons out of their orbit upon collision.
As you know the human body is also made up of atoms and molecules and so when this happens, cell communication is disrupted, and the cells do not know how to behave anymore, and they start to grow in an uncontrolled manner, resulting in tumors, cancer.
You can also see this in the Chernobyl aftermath, the body deformations, birth defects and etc. the radiation overdose caused all of this.
So it's not to be taken lightly.
There is a difference between ingesting a radioactive substance and exposing yourself to external radiation, but these words are just to illustrate the dangers involved.
I still believe that there are secrets to be found in this area.
When you radiate for example a solar panel or even an array of diodes they put out a DC voltage, which can be loaded.
But more interesting seems to be the photo electric effect these rays have directly on metals, by causing secondary emission you can change the charge on the metal, and nature will re-balance this charge which could mean that this mechanism may be used to interact with the wheelwork of nature or the earth's electric field, and there is also many times a radioactive element in many setups you come across be it the Hubbard transformer that was said to be coated with radium paint, or the Moray valve that seemed to have some radioactive salt or crystal in one of it's tubes.
Moray used to hang large cables over a lake, what if you would rise or sink the charge on this cable way above or below the earth's natural electric potential?
Would energy flow? and from where from and to?
There is many information missing or lost so we can only look at it and try to figure out what was going on.

Anyway if you want a real good visualization of these ray's you can see it in a so called cloud chamber: https://www.youtube.com/watch?v=ZiscokCGOhs
And most people know the sound of the geiger counter clicks, but this is not what radiation sounds like this is only the click of the ionizing moment, in reality these rays slow down in speed over distance so it should sound more like this:

[citfta]

As Turbo has said the electron beam can reach very high velocity and energy when in a vacuum.  This is the principle behind the electron beam welder.  If you are not familiar with this device here is a link to some information about them.  I used to work on them before I retired.  They make an absolutely clean weld.

https://en.wikipedia.org/wiki/Electron-beam_welding

This article also explains that the beam can be focused to a very sharp point for precise welding.  This focusing is also necessary to project the moving images onto the front of the CRT.

Carroll