What's the name of the light bulb in the external flash? Can I only buy it at the photographic equipment store?

There are usually two tubes in a flash. The annular tube is a flash tube, which is slender and has a normally open function. That's a modeling tube, usually a halogen tube. If there are materials on the market, the flash tube is not necessarily. It is best not to disassemble the flash tube by yourself, but to return it to the factory for maintenance.