An air ioniser (or negative ion generator or Chizhevsky's chandelier) is a device that uses high voltage to ionise (electrically charge) air molecules.
Vitamin E for hair growth is beneficial because vitamin E has the effect of a scalp massage all the time. It contains valuable antioxidants that help to keep the immune system up and improves circulation to all parts of the body, including the scalp.
Specific vitamin and mineral deficiencies like iron or vitamin B12 may be diagnosed by blood tests and treated. Multiple vitamins, including biotin, have been promoted for hair growth, but solid scientific studies for many of these claims are lacking. While taking biotin and other supplements marketed for hair, skin, and nails probably won't worsen anything, it may also not necessarily help the situation. Therefore, advertised hair-regrowth supplements should be approached with mild caution.