XP earnings are based on % damage caused x targets level multiplier.
Each level is twice the amount of the previous level soooooo
Level 0 multiplier - 1 (100% = 100xp)
Level 1 multiplier - 2 (100% = 200xp)
Level 2 multiplier - 4 (100% = 400xp)
....
Level 10 multiplier - 1024 (100% = 102,400xp)
Level 11 multiplier - 2048 (100% = 204,800xp)
Of course if you want a break down ...
00:24 AvRad transforms into a Jet and strafes Aviana. Aviana is slightly damaged (84% power remaining).
Damaged caused - 16% Level multiplier - 64 = 1024
Easy.
This is why a lot of guys head for the 1-11 missions in the hopes of catching a level 10 or 11. Just 1% of damage against a level 11 will net 2,048xp.