Two discharge modes of a repetitive nanosecond pulsed helium glow discharge under sub-atmospheric pressure in the repetition frequency range of 20 to 600 kHz
| Autor: | Akira Otsubo, Mitsuyasu Yatsuzuka, Masayoshi Nagata, Takuya Maegawa, Yoshimi Nishimura, Yusuke Kikuchi |
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| Rok vydání: | 2018 |
| Předmět: |
010302 applied physics
Glow discharge Materials science Atmospheric pressure chemistry.chemical_element Nanosecond Condensed Matter Physics 01 natural sciences Secondary electrons Cathode 010305 fluids & plasmas Afterglow law.invention chemistry law Ionization 0103 physical sciences Atomic physics Helium |
| Zdroj: | Plasma Sources Science and Technology. 27:05LT01 |
| ISSN: | 1361-6595 |
| Popis: | Two discharge modes, α and γ, of a repetitive nanosecond pulsed helium glow discharge at a gas pressure of 10 kPa in the repetition frequency range from 20 to 600 kHz are reported for the first time. The pulsed glow discharge is produced in a pair of parallel plate metal electrodes without insertion of dielectrics. The α mode discharge is volumetrically produced in the electrode gap at a low-repetition frequency, whereas the γ mode discharge is localized at the cathode surface at a high-repetition frequency. At high-repetition frequency, the time interval between voltage pulses is shorter than the lifetime of the afterglow produced by the preceding discharge. Then, the γ mode discharge is maintained by a large number of secondary electrons emitted from the cathode exposed to high-density ions and metastable helium atoms in the afterglow. In the α mode discharge with a low-repetition frequency operation, primary electrons due to gas ionization dominate the ionization process. Thus, a large discharge voltage is needed for the excitation of the α mode discharge. It is established that the bifurcation of α-γ discharge mode, accompanied by a decrease in the discharge voltage, occurs at the high-repetition frequency of ~120 kHz. |
| Databáze: | OpenAIRE |
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