Demonstration of multi-generational growth of tungsten nanoparticles in hydrogen plasma usingin situlaser extinction method

Abstract

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+// 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.

Design of model tokamak particles for future toxicity studies: Morphology and physical characterization

“…In that case, the dusty plasma laboratory conditions could be at play, leading to the creation by accretion of very small particles: their expected size is much smaller than those currently collected in W tokamaks, with dimensions ranging from 10s to 100s of nm [12]. Similarly, multigenerational formation of 30-70 nm diameter particles was also observed through the sputtering of a tungsten samples by hydrogen plasma [13]. This creation process triggers a complex surface morphology, with particles with high Specific Surface Area (SSA) and therefore high surface reactivity.…”

Thermal balance of tungsten monocrystalline nanoparticles in high pressure magnetron discharges

“…19 The production of W-dust in the context of plasma fusion is also explored since tungsten has been selected as plasma-facing component for the next generation of tokamaks. 20 In this context, the W-dust/NP production was simulated with various plasma sources such as a quasi-stationary plasma accelerator, 21 magnetron discharges using the MS-GAS system, 13 ECR microwave discharges, 22 as well as laser and electron beam interactions with W-targets. 23,24 Basic studies on the formation of W-NPs in arc discharges, 25 sputtering discharges without magnetic field, 26,27 conventional magnetron discharges 28,29 and using the MS-GAS system have also been reported.…”

Forces applied to nanoparticles in magnetron discharges and the resulting size segregation

“…The later extend from electronics, 1 optics, 2 catalysis 3 to biology as nanoscale materials have improved properties compared to those of bulk materials. Studies on the dust nucleation and growth have been made extensively in various sources of low temperature reactive plasmas such as radio-frequency (RF) [4][5][6] and direct-current (DC) sources, [7][8] in presence of magnetic fields in gas-aggregation systems based on magnetron discharges (MS-GAS) 9,10 or in conventional magnetron discharges, 11,12 in microwave plasmas combined with DC plasmas, 13 electron cyclotron resonance (ECR) plasmas 14 and strongly magnetized RF plasmas. 15 The production of dust has also been investigated in tokamaks.…”