5.1.1. Impact of the Coil Gun Structure

As presented in the results section, increasing the number of coils allows to transfer more power to the ball as shown in Table 2:

**Table 2.** Optimal ball speed depending on the number of coils in the EML.


Increasing the number of coils from one to two allows to increase the speed by 18%, corresponding to an energy transfer optimization of 40%. However, increasing the number of coils from two to three or four allows to increase the speed by only respectively 0.6% and 1.8%, corresponding to an energy transfer optimization of respectively 1.2% and 3.6%. This result is not intuitive and is important. Consequently, considering the impact of adding a coil to the EML in terms of mechanical and electrical integration, the two-coil EML seems to be the best configuration in our case.

#### 5.1.2. Comparison between the Reference Case and the Chosen Configuration

Comparing the reference situation described in [11], optimization of the number of coils of the EML, the initial position and the extension length leads to increase the ball speed by 42%, from 11.2 m·s−<sup>1</sup> to 16 m·s<sup>−</sup>1. This corresponds to an energy transfer improved by 104% compared to the reference situation, without complicating the coil gun structure too much.

Shooting range, which is defined as the distance of the first rebound in case of a 45◦ kick, without considering air friction, increases from 12.5 m in the reference situation described in [11] to 26 m in the optimal configuration.
