cathode ray in a vacuum

[KlausZahn]

I have learned that a vacuum is a space without matter. In this room, the cathode ray moves forward without distraction. Does the beam really move completely forward, or is the beam still distracted by something else (for example, gravity)?
Thanks for your answers

[studiot]

The link I gave you in your other thread should answer this one as well.

An electron beam can be deflected by electrostatic or electromagnetic fields.

The electrons are travelling too fast for there to be a measurable gravitational effect over the distances of a typical cathode ray.

[tinkerer]

On 12/8/2018 at 11:06 AM, studiot said:

The link I gave you in your other thread should answer this one as well.

An electron beam can be deflected by electrostatic or electromagnetic fields.

The electrons are travelling too fast for there to be a measurable gravitational effect over the distances of a typical cathode ray.

Now, given the great distances of travel possible for, say, a Beta Particle Accelerator, would gravitational effects be ignored? 

Back to the cathode ray tube, Television: for each and every electron which strikes the illumination screen, another must be drawn from it, in order to prevent an excess of them collecting there. This is (was) accomplished by making the CRT a large capacitor, the dielectric being the glass envelope, the walls of which were coated inside and out with a conductive film. High positive voltage applied to the inside coating "drew" those excess electrons away from the screen creating a circuit for current flow separate from that of the electron beam itself.

Studying this in Technical School in 1962, I told myself, "This cannot possibly work!". Yet, it did.

[studiot]

7 hours ago, tinkerer said:

1)Now, given the great distances of travel possible for, say, a Beta Particle Accelerator, would gravitational effects be ignored? 

2)Back to the cathode ray tube, Television: for each and every electron which strikes the illumination screen, another must be drawn from it, in order to prevent an excess of them collecting there. This is (was) accomplished by making the CRT a large capacitor, the dielectric being the glass envelope, the walls of which were coated inside and out with a conductive film. High positive voltage applied to the inside coating "drew" those excess electrons away from the screen creating a circuit for current flow separate from that of the electron beam itself.

Studying this in Technical School in 1962, I told myself, "This cannot possibly work!". Yet, it did.

2) Yes

1) Consider the relative strengths of the four fundamental forces. This table is from Wolfram Science

 

http://scienceworld.wolfram.com/physics/FundamentalForces.html

 

This is why gravity doesn't strip the electrons out of atoms.

I think they try to keep the paths of the accelerated particles horizontal in large scale accelerators.
Also there are regular repeater coils or E/S deflector plates in the installation.

Perhaps someone with direct experience of these things will chip in here, especially if they have a better answer?

 

Edited December 12, 2018 by studiot

[swansont]

1 hour ago, studiot said:

I think they try to keep the paths of the accelerated particles horizontal in large scale accelerators.
Also there are regular repeater coils or E/S deflector plates in the installation.

Perhaps someone with direct experience of these things will chip in here, especially if they have a better answer?

Consider that for circular devices (i.e. not linear accelerators) the particles will make many trips around the ring before attempting to undergo a collision — you have to speed them up, and you may need to accumulate a certain population before trying for an interaction. So keeping the beam (or bunch) in a horizontal path is required. Small deviations can be tolerated because the confining forces are much stronger than gravity.

 

"The SPS injects beams into the LHC, with one beam traveling clockwise and the other going counterclockwise.

Inside the LHC, the beams continue to accelerate. This takes about 20 minutes. At top speed, the beams make 11,245 trips around the LHC every second."

https://science.howstuffworks.com/science-vs-myth/everyday-myths/large-hadron-collider4.htm

[Strange]

!

Moderator Note

Moved to Physics

 

[tinkerer]

My point here regarding electron movement within a highly evacuated space is that when I studied and attempted to assimilate it, much less understanding beyond the very basics existed (1962 or so). We had magnets glued to the necks of CRTs which were "Degaussing" devices, for example. No instructors back then explained their theoretical function. But we did greatly enjoy drawing arcs of high-voltage high-frequency origin off of the Horizontal Output Tubes! 

[swansont]

8 hours ago, tinkerer said:

My point here regarding electron movement within a highly evacuated space is that when I studied and attempted to assimilate it, much less understanding beyond the very basics existed (1962 or so). We had magnets glued to the necks of CRTs which were "Degaussing" devices, for example. No instructors back then explained their theoretical function. But we did greatly enjoy drawing arcs of high-voltage high-frequency origin off of the Horizontal Output Tubes! 

I find the notion that deflection of moving charges was unexplained in physics instruction before 1962 to be highly dubious

[studiot]

2 hours ago, swansont said:

I find the notion that deflection of moving charges was unexplained in physics instruction before 1962 to be highly dubious

Indeed, the subject was called electron ballistics in the UK and was vital to the design and production of all valves. +1

Large sections of repected texts of the era were devoted to the subject eg

Electron Physics and Technology

Thomson (not the JJ)  & Callick

Principles of Electronics

Gavin  & Houldin

Both from English Universities Press

 

And slightly later from America (1967)

Owen and Keaton devote nearly a the wole of volume 2 of a thre volume tome

Fundamentals of Electronics

Harper Row

to it.

 

[tinkerer]

On 12/15/2018 at 6:59 AM, swansont said:

I find the notion that deflection of moving charges was unexplained in physics instruction before 1962 to be highly dubious

Of course they were explained, but not adequately to a bunch of ruffian young men drawn from every imaginable walk of young adulthood, farmers, recent high school grads (like me), recent military dischargees. The Degaussing magnet I would have to search, today easily done. Thanks for your response.

[swansont]

6 hours ago, tinkerer said:

Of course they were explained, but not adequately to a bunch of ruffian young men drawn from every imaginable walk of young adulthood, farmers, recent high school grads (like me), recent military dischargees. The Degaussing magnet I would have to search, today easily done. Thanks for your response.

CRT steering magnets and degaussing magnets are two very different applications. Permanent magnets would not be used for the latter.

[studiot]

25 minutes ago, swansont said:

CRT steering magnets and degaussing magnets are two very different applications. Permanent magnets would not be used for the latter.

Excellents points.

I would add that for CRTs magnetic deflection was generally used for television purposes and electrostatic for scope type displays.

Here are some details and pics of the very first scope I owned - and ex military type 13a, which I bought in 1968.

https://www.thevalvepage.com/testeq/hartley/13a/13a.htm

Edited December 17, 2018 by studiot

[tinkerer]

On 12/17/2018 at 3:34 AM, swansont said:

CRT steering magnets and degaussing magnets are two very different applications. Permanent magnets would not be used for the latter.

So true. Steering magnets are a new term to me; however, I do recall the smaller CRTs, such as used for oscilloscopes used charged deflection plates, vertical and horizontal, mounted within the envelope. Large CRTs such as TV used electromagnetic deflection via coils surrounding the CRT neck. Those were called "sine coils", for reasons I never learned.