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PKE-Nefedov Symposium - 2004. Measurements of Ion Drag Force acting on a Probe Particle in a DC Discharge. A.Usachev, V.Esenkov, A.Zobnin. Institute for High Energy Densities of RAS. Content: Electron microscopy of the probe microparticles. Experimental method and results.
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PKE-Nefedov Symposium - 2004 Measurements of Ion Drag Force acting on a Probe Particle in a DC Discharge A.Usachev, V.Esenkov, A.Zobnin Institute for High Energy Densities of RAS
Content: • Electron microscopy of the probe microparticles. • Experimental method and results. • Comparison experimental results with the modern theories of ion drag force. Institute for High Energy Densities of RAS
Electron microscopy of the probe microparticles. Hitachi S405A scanning electron microscope MF 4.00 0.08 m Institute for High Energy Densities of RAS
MF 4.00 0.08 m Institute for High Energy Densities of RAS
MF 6.86 0.12 m Institute for High Energy Densities of RAS
MF 6.86 0.12 m Institute for High Energy Densities of RAS
Results on Particle Size Measurements New measurements: Aug.2004 Old measurements: May.2004 Institute for High Energy Densities of RAS
2. Experimental method and results. Injector Probe particles Anode PK-4 tube Vacuum pump IDC= 0.5, 1.0, 1.5 мА p = 20, 40, 60 Pа Phantom-5 Fill gas Laser knife Laser 400 mW Cathode Mirror Cylindrical telescope Spherical telescope Institute for High Energy Densities of RAS
Setup for measurements of Ion drag force Institute for High Energy Densities of RAS
Observation of falling probe particles Particles – MF-F, r= 2,00 m Neon pressurep = 60,2 Pа Discharge currentI = 0,5 мА Institute for High Energy Densities of RAS
Data treatment а – particle radius r - mass density mn – neon atom mass nn– neon atoms density Zd – particle charge p – velocity of falling probe particle n,th– mean thermal velocity of neon atoms Institute for High Energy Densities of RAS
Determination of Delta Measured particle velocities in neutral gas a = 2,00 m,p =60 Pа, p = 7,3 см/s,I =0мА. Institute for High Energy Densities of RAS
Experimental data on δ: a) using passport data on diameter: b) using measured data on diameter: Institute for High Energy Densities of RAS
Measured particle velocities Institute for High Energy Densities of RAS
Electric force Zd fora = 3,43 m Institute for High Energy Densities of RAS
Zd fora = 2,00мкм Institute for High Energy Densities of RAS
Ion drag force vs dc for (P=20 Pа,P=40 Pа,P=60 Pа) а = 2.00 мкм а = 3.43 мкм experiment Theory а = 3.43 мкм Institute for High Energy Densities of RAS
Comparison of different forces acting on a probe particle a= 3,43 мкм a = 2,00мкм Institute for High Energy Densities of RAS
Theoretical models: • “Classic” with r=rDion (M.S.Barnes, J.H.Keller, et al., Phys. Rev. 68, 313 (1992) ). • Enhanced “classic” with r=rD_el(S.A.Khrapak, A.V.Ivlev, G.E.Morfill, and H.M.Thomas, Phys. Rev. 66, 046414 (2002) ). • “Strong interaction”(S.A.Khrapak, A.V.Ivlev, G.E.Morfill, S.K.Zhdanov, and H.M.Thomas, EEE Trans. Plasmas Sci. (2004), to be published). Institute for High Energy Densities of RAS
bp/2 bc “Classic” model [1] а – probe particle radius mi – neon atom mass s – potential of particle surface ui – ion drift velocity qi – ion charge Qd – particle charge Institute for High Energy Densities of RAS
Enhanced “classic” model [2] Applicable atb < 5 We have Institute for High Energy Densities of RAS
Enhanced “classic” model Applicable for b >>1 (strong interactions) Analytic approximation of the cross-section is Institute for High Energy Densities of RAS
Comparison of the experimental results with the theories for and d=6.2m : (P=20 Pа,P=40 Pа,P=60 Pа) а) б) в) Barnes et al: Khrapak1 et al: Khrapak2 et al: Institute for High Energy Densities of RAS
