科研之友
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摘要
A small mixing-type unipolar charger for nanoparticles (SMUC) was developed to increase the charging efficiency and throughput by using a small charging chamber (0.5 cm(3)) to reduce particle loss caused by electrostatic dispersion. The two main components of the SMUC are a high-pressure corona ionizer (HPC Ionizer) in which high concentration unipolar ions are generated, and a charging chamber in which the unipolar ions are mixed with nanoparticles without an external electric field. The charging performance of the SMUC was evaluated experimentally by measuring the charging ratio f(c) and the penetration ratio f(p). For positive charging in the particle size range of 5-40 nm, f(c)(+) = 0.91-0.95 and f(p)(+) = 0.71-0.90, at an ion concentration of N(g)(+=) 5.25 x 10(9) ions/cm(3) and a charging time t(R) = 0.025 s. For negative charging, integral(-)(c) = 0.74-0.93 and f(p)(-) = 0.73-0.85, at N(g)(-) = 6.24 x 10(9) ions/cm(3) and t(R) = 0.025 s. Based on these results, the extrinsic charging efficiency defined as f(e) = f(c) x f(p) /f(d) (where f(d) is the dilution rate) was f(e)(-) = 0.46-0.66 and f(e)(+) = 0.59-0.71 for negative and positive charging. The f(c)(+) and f(c)(-) were estimated theoretically with and without electrostatic dispersion to clarify the effect of electrostatic dispersion on particle losses in the charging chamber. The measured f(e) for d(p) < 10 nm in the 0.5 cm(3) chamber is higher than the theoretical results without electrostatic dispersion, indicating that particle loss caused by electrostatic dispersion is reduced by use of the small volume charging chamber.
- 出版日期2010
