A Bucks County man who admitted hitting his wife on the head with a hammer has been given 2 ½ to 5 years in state prison, followed by ten years probation. 50-year-old Jim Wang of Churchville pleaded guilty but mentally ill to aggravated assault.  Prosecutors say the couple had been separated for about two weeks last October when Wang asked his wife, Carrie Zhu, to come to his house and talk.  She joined him in a hot tub, and as she got out he hit her from behind with a hammer, which he had hidden in the bathroom, and bit her on the leg, but she fought back, escaped and drove to a hospital for treatment.