2003 Fiscal Year Final Research Report Summary
Production and Spectroscopic Measurement of Dust Plasma in Superfluid Liquid Helium
| Project/Area Number |
14580514
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
プラズマ理工学
|
|---|
| Research Institution | NIIGATA UNIVERSITY |
|---|
Principal Investigator |
MINAMI Kazuo NIIGATA UNIVERSITY, Faculty of Engineering, Professor, 工学部, 教授 (00023135)
|
|---|
| Project Period (FY) |
2002 – 2003
|
| Keywords | Liquid Helium / Dusty Plasma / Pulsed Discharge / Stark Broadening / Impurity Injection / Spectroscopy / Magnesium / Needle Electrodes |
|---|
| Research Abstract |
Spectroscopic measurement of dusty plasma produced by high voltage pulsed discharge in superfluid liquid helium(LHe) is carried out. First, we tried to dissolve powder of silver(Ag) fine particle with diameter 0.07μm into LHe. Evaporation of LHe is enhanced by the fine particles, and they have tendency to adhere the wall of Dewar bottle which prevents optical observation. Next, we tried various metal rods as an electrode to initiate high voltage pulsed discharge that is ablated into LHe. So far, we are successful only to ablate magnesium(Mg) particles into LHe from the solid electrode. Tungsten(W) electrode with and Mg rod with 1mm diameter are fixed along a common axis at the bottom of the Dewar bottle filled with superfluid LHe. The light intensity of collimated image of the source is introduced into optical spectrometer and time-resolved spectral line intensities produced dusty plasma are measured by multi-channel image intensifier(Hamamatsu, PMA-50). Spectral intensities of the light between the electrodes in 1 atmosphere helium gas at room temperature are measured. MgI line intensity at 518.2nm shows that the intensities are fifteen times stronger and light lasts for longer time for the case of that Mg rod is cathode rather than the case that the polarity is opposite. Then, the electrodes are immersed in LHe with the former polarity. During the pulsed discharge, intense continuum lights and strong HeI triplet line at 587.6nm are observed that means the presence of high-density plasma. The light from the plasma is extinguished at 20μs after the pulsed discharge because of cooling effect of ambient LHe. On the other hand, MgI lines at 518.2 and 552.8nm can be observed until 35μs, after the helium plasma ends. Plasma of ablated Mg dusty particles is estimated to be produced in the LHe. The sizes of the localized dusty plasma are measured in some detail. The sizes of the dusty particle are remained to be examined in future.
|
Research Products
(4 results)
