Abstract: An experimental device for small-sized point discharge with adjustable discharge gap is designed
based on a dual-resonance solid-state Tesla coil．The indirect measurement method was used to measure the
induced voltage on the plate when the distance between the needle tip and the plate changes，and the laws of
point discharge characteristics were systematically studied．The study found that when the distance between the
needle tip and the plate reaches a critical value，there is an obvious abrupt change in the discharge
phenomenon:high-voltage arc discharge occurs when the distance is less than the critical value，while small-
angle spark discharge at the needle tip occurs when the distance is greater than the critical value．The device is
convenient to operate and has intuitive experimental phenomena，making it suitable for university physics
teaching demonstrations and photoelectric characteristic research．
