Here is the full list of all 18 Ion Assault achievements.
Survive 3 stages in a row without losing a life.
Complete a regular stage without collecting a single Power-Up.
Finished a stage in less than 90 seconds.
Score exceeds 500,000 points (Campaign).
Destroy seven asteroids at once.
Destroy five asteroids at once.
Destroy 50 big asteroids in a single game.
Completed the single player campaign.
Complete a whole sector without dying once.
Score exceeds 1,500,000 points (Campaign).
Get two extra-lives with a single score upload.
Score exceeds 500,000 points (Survival).
Score exceeds 1,000,000 points (Survival).
Score exceeds 2,500,000 points (Survival).
Score exceeds 5,000,000 points (Survival).
Score exceeds 10,000,000 points (Survival).
Score exceeds 3,000,000 points (Campaign).
Score exceeds 5,000,000 points (Campaign).