3 ms·

A vacuum tube in an amplifier is more of an electron attenuator than it is an accelerator. The electrons don't actually gain any energy in these vacuum tubes pa

A vacuum tube in an amplifier is more of an electron attenuator than it is an accelerator. The electrons don't actually gain any energy in these vacuum tubes past the energy they have when emitted. They still travel at the same "speed" that they normally would around an atom, the only difference is that they are freed from the atom. Acceleration is not part of what an amplifier tube does.

__MatrixMan__ 3y ago
> They still travel at the same "speed" that they normally would around an atom Can you unpack "speed" there? I figured the speed of an electron in an orbital was the same as the speed of the atom. Certainly there's some energy associated with it being in that particular orbital, and if it takes on more energy then the region in which it might be measured will expand, but it's not like zooming around in there is it?
- leptons 3y ago
  I am by no means an expert in particle acceleration, but I have worked with tube amplifiers extensively, specifically for audio (modifying and building tube guitar amplifiers). https://en.wikipedia.org/wiki/12AX7 https://en.wikipedia.org/wiki/12AX7 https://www.effectrode.com/knowledge-base/the-12ax7-tube/ https://www.effectrode.com/knowledge-base/the-12ax7-tube/ The suggestion of the parent comment to use a nano-sized particle accelerator on a chip could somehow be useful for tube amplifiers just seemed ridiculous.
  - __MatrixMan__ 3y ago
    From your username I thought you might be an expert :). All I have is a small pile of physics classes, so I'm also not an expert. Still, I agree: ridiculous. Just to nit pick your "same speed" comment though... The tube you linked to indicates 250V at the anode. Electrons have a mass of 10^-13 kg. For such a tiny thing, that voltage is positively tremendous. Even in the tiny space of the tube I think that the electrons are accelerating from 0 when at the cathode to relativistic speeds at the anode. The tube is an accelerator, and the control grid opposes that acceleration. Accelerating the electrons to even greater energies would just mean that more voltage is needed at the triodes to have any modulating effect on the signal. Also, the beam would be, well, a beam, rather than a... gust? It would either strike the anode or miss it--that's not modulating anything, that's just an on-off switch.
m3047 3y ago
For simple thermionic electricity generation, sure; this is the effect in play when the first grid gains charge with no bias applied (and a near infinite load resistance). When a positive charge is applied to the anode, the electrons do accelerate although the effect isn't comparable to a magnetron, cyclotron or linac.

__MatrixMan__ 3y ago

> They still travel at the same "speed" that they normally would around an atom Can you unpack "speed" there? I figured the speed of an electron in an orbital was the same as the speed of the atom. Certainly there's some energy associated with it being in that particular orbital, and if it takes on more energy then the region in which it might be measured will expand, but it's not like zooming around in there is it?

leptons 3y ago
I am by no means an expert in particle acceleration, but I have worked with tube amplifiers extensively, specifically for audio (modifying and building tube guitar amplifiers). https://en.wikipedia.org/wiki/12AX7 https://en.wikipedia.org/wiki/12AX7 https://www.effectrode.com/knowledge-base/the-12ax7-tube/ https://www.effectrode.com/knowledge-base/the-12ax7-tube/ The suggestion of the parent comment to use a nano-sized particle accelerator on a chip could somehow be useful for tube amplifiers just seemed ridiculous.
- __MatrixMan__ 3y ago
  From your username I thought you might be an expert :). All I have is a small pile of physics classes, so I'm also not an expert. Still, I agree: ridiculous. Just to nit pick your "same speed" comment though... The tube you linked to indicates 250V at the anode. Electrons have a mass of 10^-13 kg. For such a tiny thing, that voltage is positively tremendous. Even in the tiny space of the tube I think that the electrons are accelerating from 0 when at the cathode to relativistic speeds at the anode. The tube is an accelerator, and the control grid opposes that acceleration. Accelerating the electrons to even greater energies would just mean that more voltage is needed at the triodes to have any modulating effect on the signal. Also, the beam would be, well, a beam, rather than a... gust? It would either strike the anode or miss it--that's not modulating anything, that's just an on-off switch.

m3047 3y ago

For simple thermionic electricity generation, sure; this is the effect in play when the first grid gains charge with no bias applied (and a near infinite load resistance). When a positive charge is applied to the anode, the electrons do accelerate although the effect isn't comparable to a magnetron, cyclotron or linac.