Electron heating and particle fluxes in dual frequency atmospheric-pressure helium capacitive discharge.

In this letter, a 1D fluid model has been used to study the electron heating and particle transport in dual frequency atmospheric-pressure helium capacitive discharge with a high-frequency (HF) voltage of 10 MHz and a low-frequency (LF) voltage of 1 MHz. The electric field is decoupled to three components: the HF, the LF and the direct current (DC) ones, and they have much different effects on the plasmas. The eletrons in plasma bulk are mainly heated by the HF electric field, while in plasma sheath they are heated and cooled by the LF and DC electric fields, respectively. With a fixed total input power, the increase of LF power leads to great enhancement of the electrode fluxes of electrons and ions, especially for the energetic electrons of Te  >  2 eV, because more power is dissipated in the vicinity of electrodes and the inelastic collision is more pronounced. Therefore, the particle transport on the treated sample can be greatly enhanced without additional gas heating in dual frequency plasmas, which meets the application requirements more compared to the single frequency plasmas. [ABSTRACT FROM AUTHOR]