section_path: New York laboratories/X-ray experimentation
section_name: X-ray experimentation
paragraph_text: X-ray experimentation
  
  Starting in 1894, Tesla began investigating what he referred to as radiant energy of "invisible" kinds after he had noticed damaged film in his laboratory in previous experiments (later identified as "Roentgen rays" or " X-rays "). His early experiments were with Crookes tubes, a cold cathode electrical discharge tube. Tesla may have inadvertently captured an X-ray image—predating, by a few weeks, Wilhelm Röntgen 's December 1895 announcement of the discovery of X-rays—when he tried to photograph Mark Twain illuminated by a Geissler tube, an earlier type of gas discharge tube. The only thing captured in the image was the metal locking screw on the camera lens.
  
  In March 1896, after hearing of Röntgen's discovery of X-ray and X-ray imaging (radiography), Tesla proceeded to do his own experiments in X-ray imaging, developing a high-energy single-terminal vacuum tube of his own design that had no target electrode and that worked from the output of the Tesla coil (the modern term for the phenomenon produced by this device is bremsstrahlung or braking radiation). In his research, Tesla devised several experimental setups to produce X-rays. Tesla held that, with his circuits, the "instrument will... enable one to generate Roentgen rays of much greater power than obtainable with ordinary apparatus".
  
  Tesla noted the hazards of working with his circuit and single-node X-ray-producing devices. In his many notes on the early investigation of this phenomenon, he attributed the skin damage to various causes. He believed early on that damage to the skin was not caused by the Roentgen rays, but by the ozone generated in contact with the skin, and to a lesser extent, by nitrous acid. Tesla incorrectly believed that X-rays were longitudinal waves, such as those produced in waves in plasmas. These plasma waves can occur in force-free magnetic fields.
  
  On 11 July 1934, the New York Herald Tribune published an article on Tesla, in which he recalled an event that occasionally took place while experimenting with his single-electrode vacuum tubes. A minute particle would break off the cathode, pass out of the tube, and physically strike him:
  
  Tesla said he could feel a sharp stinging pain where it entered his body, and again at the place where it passed out. In comparing these particles with the bits of metal projected by his "electric gun", Tesla said, "The particles in the beam of force... will travel much faster than such particles... and they will travel in concentrations".