Everybody is missing something here. Not only can you try criminal prosecution -- and you should keep at it -- but you can also sue. Deliver a legal notice for a suit in small claims court, suing for the statutory maximum. Every single attack can be considered a new incident and a valid reason to sue again. And if you bring some friends along, each one can sue the guy separately.
As far as personal self-defense goes, you should read up on your own state's weapon laws. Even if you're not prepared for a fight, I bet you know at least one person who will go along with you; someone who has a hand weapon and knows how to use it (or a cordite-based projectile weapon, depending on your state laws).