Demonstration of multi-generational growth of tungsten nanoparticles in hydrogen plasma using in situ laser extinction method

For the first time, we demonstrate that tungsten (W) nanoparticles (NPs) are created when a tungsten target is exposed to low-pressure, high density hydrogen plasma. The plasma was generated using a novel dual plasma system combining a microwave discharge and a pulsed direct-current (DC) discharge. The tungsten surface originates in the multi-generational formation of a significant population of 30-70 nm diameter particles when the W cathode is biased at ∼ -1 kV and submitted to ∼10²⁰ m² s^-1 H⁺/H₂⁺/H₃⁺ ions flux. The evidenced NPs formation should be taking into account as one of the consequence of the plasma surface interaction outcomes, especially for fusion applications.