Gauss gun

Shooting Principle Illustration

Gauss gun ( English Gauss gun, Coil gun, Gauss cannon ) - one of the varieties of electromagnetic mass accelerator. Named after the German scientist Karl Gauss , who laid the foundations of the mathematical theory of electromagnetism . It should be borne in mind that this method of accelerating the masses is mainly used in amateur installations, as it is not effective enough for practical implementation. By its principle of operation (creating a traveling magnetic field) it is similar to a device known as a linear motor .

Content

1 Principle of operation
2 Application
3 Creation
4 Advantages and disadvantages
5 In the literature
6 See also
7 References
8 Notes

Principle of Operation

A Gaussian gun consists of a solenoid , inside of which is a barrel (usually a dielectric ). A projectile made of a ferromagnet is inserted into one of the ends of the barrel. When an electric current flows in the solenoid, an electromagnetic field appears, which accelerates the projectile, "pulling" it into the solenoid. At the ends of the projectile, poles are formed, oriented according to the poles of the coil, because of which, after the passage of the center of the solenoid, the projectile is attracted in the opposite direction, that is, it is braked. In amateur circuits, a permanent magnet is sometimes used as a projectile, since it is easier to deal with induction EMF resulting from this. The same effect occurs when using ferromagnets , but it is not so pronounced due to the fact that the projectile is easily magnetized ( coercive force ).

For the greatest effect, the current pulse in the solenoid should be short-term and powerful. As a rule, electrolytic capacitors of large capacity and high operating voltage are used to obtain such a pulse.

The parameters of the accelerating coils, projectile and capacitors should be coordinated so that when firing to the moment the projectile approaches the solenoid, the magnetic field induction in the solenoid is maximum, but with a further approach of the projectile it drops sharply. It is worth noting that different algorithms for the operation of accelerating coils are possible.

Kinetic energy of the projectile

E={mv^{2} \over 2}

{\ displaystyle E = {mv ^ {2} \ over 2}}

m

{\ displaystyle m}

- mass of the shell

v

{\ displaystyle v}

- his speed

The energy stored in the capacitor

E={CU^{2} \over 2}

{\ displaystyle E = {CU ^ {2} \ over 2}}

U

{\ displaystyle U}

- capacitor voltage

C

{\ displaystyle C}

- capacitor capacity

Capacitor Discharge Time

This is the time during which the capacitor is completely discharged:

T={\pi {\sqrt {LC}} \over 2}

{\ displaystyle T = {\ pi {\ sqrt {LC}} \ over 2}}

L

{\ displaystyle L}

- inductance

C

{\ displaystyle C}

- capacity

Inductor Run Time

This is the time during which the EMF of the inductor increases to its maximum value (full discharge of the capacitor) and completely drops to 0. It is equal to the upper half-period of the sine wave.

T=2\pi {\sqrt {LC}}

{\ displaystyle T = 2 \ pi {\ sqrt {LC}}}

L

{\ displaystyle L}

- inductance

C

{\ displaystyle C}

- capacity

It is worth noting that in the presented form the last two formulas cannot be used for calculating the Gaussian gun, if only for the reason that as the projectile moves inside the coil, its inductance changes all the time.

Application

It is theoretically possible to use Gauss cannons to launch light satellites into orbit, since with stationary use it is possible to have a large source of energy. The main application is amateur installations, a demonstration of the properties of ferromagnets . It is also quite actively used as a children's toy or developing a home-made installation of technical creativity (simplicity and relative safety)

Creation

The simplest constructions can be assembled from improvised materials even with school knowledge of physics ^[1]

There are many sites that detail how to assemble a Gaussian gun. But it is worth remembering that the creation of weapons in some countries can be prosecuted by law. Therefore, before creating a Gaussian gun, it is worth considering how you will use it.

Advantages and disadvantages

The Gauss gun as a weapon has advantages that other types of small arms do not have. This is the absence of shells and the unlimited choice of the initial velocity and energy of the ammunition , the possibility of a silent shot (if the speed of a sufficiently streamlined projectile does not exceed the speed of sound ), including without changing the barrel and ammunition, relatively small recoil (equal to the momentum of the projectile that has fired, there is no additional impulse from the powder gases or moving parts), theoretically, greater reliability and, in theory, wear resistance , as well as the ability to work in any conditions, including in outer space .

However, despite the apparent simplicity of the Gauss gun, using it as a weapon is fraught with serious difficulties, the main of which is the large expenditure of energy.

The first and main difficulty is the low efficiency of the installation. Only 1-7% of the capacitor charge goes into the kinetic energy of the projectile. In part, this drawback can be compensated for by using a multi-stage projectile dispersal system, but in any case, the efficiency rarely reaches 27%. Basically, in amateur installations, the energy stored in the form of a magnetic field is not used in any way, but is the reason for using powerful keys ( IGBT modules are often used) to open the coil ( Lenz rule ).

The second difficulty is high energy consumption (due to low efficiency).

The third difficulty (follows from the first two) is the large weight and dimensions of the installation with its low efficiency.

The fourth difficulty is the rather long accumulative recharge time of the capacitors , which makes it necessary to carry a power source (usually a powerful battery ) along with a Gaussian gun, as well as their high cost. It is theoretically possible to increase the efficiency if superconducting solenoids are used, but this will require a powerful cooling system , which brings additional problems and seriously affects the scope of the installation. Or use replaceable battery capacitors.

The fifth difficulty is that with an increase in the velocity of the projectile, the duration of the magnetic field, during the passage of the solenoid by the projectile, is significantly reduced, which leads to the need not only to turn on each subsequent coil of the multi-stage system in advance, but also to increase the power of its field in proportion to the reduction of this time. Usually this drawback is immediately overlooked, since most home-made systems have either a small number of coils or insufficient bullet speed.

In an aqueous environment, the use of a gun without a protective casing is also seriously limited - remote induction of current is sufficient for the salt solution to dissociate on the casing with the formation of aggressive (dissolving) media, which requires additional magnetic shielding.

Thus, today the Gauss gun has no prospects as a weapon, since it is significantly inferior to other types of small arms that work on other principles. Theoretically, prospects, of course, are possible if compact and powerful sources of electric current and high-temperature superconductors (200-300K) are created. However, an installation similar to a Gaussian cannon can be used in outer space, since under the conditions of vacuum and weightlessness, many of the shortcomings of such installations are leveled. In particular, the military programs of the USSR and the USA considered the possibility of using installations similar to a Gaussian cannon on orbiting satellites to hit other spacecraft (with shells with a large number of small striking parts), or objects on the earth's surface.

In the literature

Quite often in the literature of the science fiction genre , the Gauss gun is mentioned. She acts there as a high-precision deadly weapon.

An example of such a literary work is books from the STALKER series, written from the STALKER series of games, where the Gauss gun was one of the most powerful weapons, not counting RPG-7.

But the first in science fiction, the Gauss cannon was realized by Harry Harrison in his book Revenge of the Steel Rat . A quote from the book: “Everyone had a Gaussian with them - multi-purpose and especially deadly weapons. Its powerful batteries accumulated an impressive charge. When the trigger was pulled, a strong magnetic field was generated in the barrel, accelerating the projectile to a speed not inferior to the velocity of the projectile of any other weapon with reactive cartridges. But the Gaussian had the superiority that it had a higher rate of fire, was absolutely silent and shot with any shells, from poisoned needles to explosive bullets. "

Links

Notes

↑ Braga N. Creating robots at home. - M.: NT Press, 2007 .-- S. 141 - ISBN 5-477-00749-4 .

[1] Braga N. Creating robots at home. - M.: NT Press, 2007 .-- S. 141 - ISBN 5-477-00749-4 .