Li Qingsong has mastered the electromagnetic cannon technology at this moment. But the electromagnetic cannon used for interception and the electromagnetic cannon used for attack are two different things. Offensive electromagnetic guns pursue lethality, the projectiles must be as large as possible, and the speed must be as fast as possible. As for the firing rate, of course, the higher the better, but the requirements are not that high. The requirement for defending against electromagnetic cannons is that the projectile must be as small as possible - it only needs to cause the orbit of the incoming electromagnetic cannon projectile to deviate by even just one centimeter. After a long journey, it will deviate greatly from the original orbit and will not be able to hit the spacecraft. This does not require too much kinetic energy, so why make the projectile so large? On the contrary, the smaller it is, the more it can carry. The requirement for muzzle velocity is actually not high, and there is no need to reach a speed of more than ten kilometers per second. Several kilometers per second, or even less than one kilometer per second, is not unacceptable. After all, we are intercepting, so we only need to calculate the trajectory of the projectile in advance, and a lower speed can just hit the high-speed projectile. The defensive electromagnetic gun does not have high requirements for the projectile mass and muzzle velocity, but instead has extremely high requirements for the firing rate. In extreme cases, the defensive electromagnetic gun must be able to fire hundreds or thousands of projectiles within one second. Because in the space battlefield, who can be sure how many projectiles will fly towards them in the next moment? Following this design idea, Li Qingsong took a lot of improvement measures on the original electromagnetic gun, and finally created a small electromagnetic gun with a barrel of only two meters, a diameter of only 10 centimeters, and a maximum muzzle velocity of only two kilometers per second - even some gunpowder gun bullets with high muzzle velocities cannot compare with it.
The projectiles fired by this electromagnetic gun are extremely small. The lightest projectile weighs only about 2 milligrams, which is roughly equivalent to the weight of a small steel ball in a ballpoint pen. Even if its muzzle velocity is as high as 2000 meters per second, its kinetic energy is only a few joules, but it doesn't matter, as long as it can cause the target projectile to deviate from its trajectory by even just one centimeter, it is enough. The extremely light mass allows a warship to carry a large number of these projectiles. After all, even if there are 500,000 of these projectiles, the total mass is only one kilogram. After completing the development of various types of defensive electromagnetic guns, Li Qingsong turned his attention to laser cannons. Lasers have an incomparable advantage over physical projectiles, which is their faster speed. The fastest electromagnetic cannon projectile has a speed of only a dozen kilometers per second, while the transmission speed of laser is the speed of light, a difference of more than 20,000 times. Defensive laser cannons are more suitable for dealing with projectiles that have entered a closer range and will soon hit the enemy if not intercepted. At the same time, Li Qingsong also plans to develop both offensive and defensive models of laser cannons. It would be a waste if such a good offensive means was not used to attack enemy spacecraft. Laser beams with extremely high energy can not only rely on traditional heat burning methods to destroy the target's armor and shells, but after quickly heating the target, they can also trigger a certain shock wave effect, causing greater damage. In addition, the extremely rapid heating effect can also destroy the structure of the material, causing it to expand rapidly at high temperatures and contract at low temperatures, directly leading to the peeling of the material and thus destroying the overall structure. Lasers have a very long history of application and have been used on a large scale in the early days of the human world, but they are rarely used in the field of weapons. The most important thing is that its technical difficulty is too high. Weapons-grade laser cannons not only require extremely high-power laser generators, but also extremely high instantaneous power, which places a huge strain on the energy supply system, even greater than that of electromagnetic guns. In addition, it has extremely high requirements for the cooling system, which is fundamentally different from the electromagnetic gun. Without a strong enough cooling system, the laser generator could melt itself in less than a second. And another most important factor is the divergence angle of the laser. Li Qingsong must create a laser with an extremely low divergence angle so that it will have practical significance. Only when the divergence angle is low enough can the laser beam be sufficiently convergent.
Suppose that when a laser beam is first emitted, its cross-sectional area is 1, and then after being transmitted for one kilometer, its cross-sectional area becomes 2. It is obvious that the energy received per unit area is reduced to half of the original value, and the lethality is greatly reduced. Similarly, decades ago, Li Qingsong had already adopted a clumsy method without any skills, accumulating brainpower and resources, developing at all costs, iterating and optimizing day after day, and finally now, decades later, he has developed a laser cannon with certain practical significance. According to previous plans, the laser cannon developed by Li Qingsong has two major series, one series is defense and the other series is offense. Under each major series, there are many models based on the laser power, wavelength, etc. At this moment, Li Qingsong started an experiment on high-energy offensive laser cannon. One thousand kilometers above Ganymede, a retired Mercury-class battleship is sailing quietly. Although it has been retired and its technology is outdated, its armor material is still relatively advanced and extremely thick. It could not be penetrated even by sustained bombardment from high-rate machine guns. But at this moment, a thousand kilometers away, a laser beam from the surface of Ganymede shone on its armor. The initial cross-section of this laser beam was only about 3 square centimeters. After being transmitted over a distance of 1,000 kilometers, the cross-section has only doubled to 6 square centimeters. Although the area has doubled and the energy received per unit area has been reduced by half, because the initial energy is high enough, it still has extremely high lethality at this moment. Under the laser irradiation, the metal material on the spacecraft's armor began to boil and explode in just a few seconds. After more than ten seconds, the surrounding armor materials were also seriously affected by the changes here, resulting in a significant decline in performance and extremely reduced protection capabilities. After half a minute, the thick armor was burned through. A large amount of gas leaked out, and the entire spacecraft lost power due to the penetration damage. After a comprehensive assessment, Li Qingsong came to a conclusion. "The power of a ship-borne combat laser cannon cannot be that high. Overall, the largest ship-borne laser cannon can maintain a certain lethality within a range of about 3,000 kilometers, and it will be useless beyond 3,000 kilometers. Very good, not bad, three thousand kilometers is enough. " Even if it's not enough, there's nothing we can do. This is the limit of Li Qingsong's skills, and he can't go any higher. After completing the inspection of the offensive laser cannon, Li Qingsong turned his attention to the defensive laser cannon.