There are many strikes in self defense and martial arts that will assist you with getting away from an assalent quickly. In an attack you have seconds and each one counts to your survival so use them wisely.
Here I will describe some powerful strikes that will give you some extra time.
For these strikes to be successful, you will need to practice them often. When practicing use fast motion because in a real situation you will want to be fast, due to your time factor.
Knee to the Groin
Lift your left or right leg so that it may be parallel to the ground, bending the knee so that it creats a 90 degree angle, into your attacker
The elbow strike can be used in a number of positions and for a number of reasons
a) When someone is attacking from behind---Arm close to body, palm up (facing forward), elbow pointing toward the ground, move your elbow straight back into your attacker
b) When someone is attacking your front----Arm close to your body, palm up (facing forward), elbow pointing toward the ground, move your elbow up into your attacker
c) When someone is attacking from your side--Arm close to your body, forearm touching your mid stomach, palm down (facing towards the ground), move elbow sideways into your attacker ribs or move your elbow up into your attackers face.
d) When someone is attacking you from your side--Wrist in front of your face, palm down (facing toward the ground), move your arm straight or slightly upward into your attacker