Vacuum electrode electrotherapy treatment 1930s

Vacuum electrode electrotherapy treatment of elbow in 1930s. Electrotherapy was a Victorian era medical field, mostly quack medicine, in which high voltage alternating current was applied to the body to treat a variety of ailments. The vacuum electrode applicator consists of a metal electrode sealed inside a partially evacuated glass bulb, which is connected by a wire to the high voltage terminal of a Tesla coil or Oudin coil. The high voltage radio frequency alternating current, 50,000 to 500,000 volts at 100 kHz to 2 MHz, passed from the electrode through the ionized gas into the patient's body. This wasn't painful for the patient because alternating currents over 10 kHz frequency do not cause the sensation of electric shock. The glass wall of the bulb formed a capacitor which served to limit the current. The high voltage ionized the gas, creating a mysterious violet glow in the bulb (not visible here), which impressed patients. Electrotherapy had its heyday after World War 1, around 1920, but declined and had virtually disappeared by the time this book was published, 1945