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Maser and laser, their structure and work.

The first maser on ammonia (NH3) was invented by scientists N. G. Basov, A. M. Prokhorov in our country, and J. Gordon, G. Zeiger, C. Townes abroad in 1954. It looked like this:

Despite its such complexity in metal, its circuit diagram is very simple.

Ammonia is injected into source 1 of the maser. Why ammonia? There are probably many reasons: there is a lot of ammonia, it is cheap, it is safe and there are many other reasons. This I mean that someone was sitting solving the Schrodinger equation and the solution indicated a high probability of the need for ammonia.

Further, at the exit from the source, a more or less narrow beam of ammonia molecules should be obtained so that they do not creep in space, but fly in the same direction, approximately parallel. This work is done by the focusing system. I think that in this case no one attracted any wave function either. Perhaps the curvature and size of the mirrors were calculated there, or some other parameters of the installation, but without the wave function. The focused beam enters the quadrupole capacitor 2. Here I took its design from the network:

It consists of two negative and two positive parallel bars.

The ammonia that is fed into the device contains both excited and non-excited molecules. Molecules spontaneously pass from one state to another, and at thermodynamic equilibrium, the ratio of the number of these molecules is approximately the same. The task of this part of the device is to divide the gas flow into two parts. It is important for us to select excited molecules from the stream and direct them to the resonator. It turns out that the electric field of this capacitor deflects unexcited molecules aside, and the excited molecules fly straight, which is what we need. And in this case, they focused more on Kaufman than on Schrodinger.

These excited molecules enter the resonator 3. The resonator is a hollow device in which photons move from one wall to the opposite wall and back. Of course, although the resonator looks like a simple device, technically its manufacture presents some difficulties: it is necessary to maintain the dimensions, in relation to the radiation wavelength, to maintain the parallelism of the walls, their reflectivity, and more.

What happens when a beam of excited ammonia molecules hits the resonator? In the resonator, the molecules are simply decelerated, the gas expands. A molecule, or rather some atom of it, emits a photon, which flies to the wall of the resonator and can be reflected from it, like from a mirror. And then it will bounce off the opposite wall again. And so several times.

The same thing happens with the rest of the emitted photons. They will all run wildly between the walls of the chamber. But if the walls of the reflecting chambers are moved so that the distance between them is a multiple of the photon radiation wavelength, the number of simultaneously reflected photons may turn out to be large. What happens to these photons?

1. In most cases, these photons, like all the others, run between the walls, transfer energy to the walls of the resonator, and simply heat it up, like a back wall in a refrigerator. But the photon may have a different fate.

2. Running from wall to wall in the resonator, a photon can meet an electron of an excited atom, which will absorb this photon, which will heat up the gas itself. The photon energy will be converted into heat.

3. But a third scenario of photon-atom behavior is also possible. An electron of an excited atom can simply retransmit (re-emit) a photon that hits it. This usually happens, this is how light spreads in any environment.

But in this case, a special, say, non-standard situation may arise. The fact is that the absorbed photon always pulls an electron towards itself, even if they are not a resonant pair. This is the usual gravity. . And an electron moving in an orbit may decelerate and fail to reach the meeting point with its exchange photon, as shown in Figure 3. (see articles ”Atom” and “Induced emission.”

In this case, the exchange photon will be emitted by the atom. And the incident photon will re-emit and return the electron to its rightful place, but it will be too late, the exchange photon will already be emitted.

And now there will be 2 necessary photons: he himself, as relayed according to Huygens, and the knocked out exchange photon. The original photon, it would seem, should be absorbed by an electron, since it is similar to an exchange one, which is always absorbed. But it was not there. An electron is ready to absorb such a photon only if it is absolutely identical to the emitted one. The difference of photons in 1 quantum (negligible part of energy) and these are completely different photons. One of them will be accurately absorbed by the electron, and the other will also be relayed exactly. And no Heisenberg principle works here.

Now we can get an avalanche process. Each photon produces 2 photons. In theory, everything is correct, but in practice it turned out to be more complicated. A noticeable radiation flux was not always obtained. Gas flows in, molecules are separated, the parameters of the resonator change, but there is still no radiation.

And what to do? And either the gas flow was increased for some reason, or it happened by accident, but with a certain gas flow through the device, the radiation intensity curve crept up sharply. And again I will have the audacity to assert that here, too, the calculations of the wave function were dispensed with.

What happened? They began to think about this phenomenon and realized that although the photons are doubling, they are still not enough so that they could interact with a sufficiently large number of molecules entering the resonator. Some of the photons were lost without finding a partner. Then they just decided to inject more molecules into the resonator. The likelihood of collisions of photons with electrons of excited atoms has increased and pulled with it an increase in the number of photons. An avalanche-like process has formed.

This is the same phenomenon as in the case of uranium 235 - it is necessary to gain critical mass. Then they calculated and it turned out that for a given maser, the critical mass is gained when the flux is 10 to 13 molecules per second. As soon as the critical mass has accumulated, then almost every photon will meet its electron and an avalanche-like process of forced radiation will occur. And although both photons and molecules will be eliminated from the process, due to multiple reflections of photons, it is possible that all molecules will react. If we could slow down time, we would see a flash in the resonator. The original material is burnt out. All molecules have entered a stationary state.

Since the flow of molecules into the resonator is continuous, it would seem that there must be a continuous process in the resonator. This is not true. The flow is very slow in relation to the avalanche process. While the process of radiation is going on into the resonator, perhaps a few molecules will fly in. As elsewhere, all this must be calculated, but not by probabilistic functions.

As soon as the photon is emitted, the critical mass continues to gain and the process repeats. Photons in the form of packages, which are described in the video “Photon.” are sent through a waveguide or cable into space. Of course, this photon is a slightly blurred structure, but not as strong as the photon from the fire. An elementary photon of the first atom can fly in front, next to or, lagging behind, still elementary photons, then again a certain amount of elementary photons, all thickening and thickening, the photon reaches a peak and then decreases. But in comparison with the duration of the photon, these fronts make up a small part of the length of the entire packet due to the avalanches of the imagery of the process.

This is how the maser works and works.

Laser, its structure and principle of operation.

We have considered a gas-powered maser, but there are also crystal-based, dye-based masers. And a lot more will be invented. Their principle of operation is the same as that of a gas maser. They differ only in the method of obtaining excited atoms. For the considered gas maser, we selected excited molecules from a mixture of ammonia and sent them to the resonator. In crystal masers, excited atoms are produced by exposing unexcited atoms to a certain amount of electromagnetic radiation.

This is done this way, a crystal of a certain size is cut. Typically, the end walls of the crystal are a resonator. An electromagnetic field is applied to this crystal, obtained in some way. The electromagnetic field transforms unexcited atoms into an excited state. Scientists call this "overpopulation." And the process of formation of "overpopulation" is called pumping. As soon as the “overpopulation” reaches a certain critical value, an avalanche-like process will immediately begin.

All excited atoms return to their original state, and the pumping process starts a new cycle.

The laser works absolutely the same way, only the wavelengths in it are shorter than that of the maser. For example, an ammonia maser has a wavelength of about 1.25 cm, while a hydrogen maser has a wavelength of 21 cm. And for lasers, the wavelengths of the optical spectrum are nanometers.

Currently, there are many types of masers and lasers: gas, liquid, and all kinds of solids. Just have time to select the pumping modes and cavity sizes. It is only important to remember that all these devices are amplified not by photons from the pump, but by exchange photons of the atom. Therefore, if you come across a picture like this:

Don't believe her. There can be no transitions without radiation. Without some loss or gain, nothing will happen. If you give something free of charge, then many others will immediately appear to receive it for free, and you will quickly end. If you get something for free, then soon you will take everything and become the Universe or God.

Basov and Prokhorov drew this picture out of despair. They did not have an atomic model, and they could not understand how green turns into red. This happens with scientists quite often. It is impossible to know everything.

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