Try a battery powered water pistol, they can hit a cat at 15 metres/yards. Put a teaspoon of washing up liquid in the water. IF you manage to wet the cat it will try to lick itself dry, discover the washing up liquid is unpleasant and usually avoid whatever caused it to get coated in washing up liquid. It works in our garden.
Your neighbours may think you have finally cracked when they spot you hiding in your car armed like Flash Gordon.
