Quantitative evaluation of the densities of active species of N₂ in the afterglow of Ar-embedded N₂ RF plasma

Ricard, A.,Oh, S.,Jang, J.,Kim, Y.K. Elsevier 2015 CURRENT APPLIED PHYSICS Vol.15 No.11

The N<SUB>2</SUB> and Ar-20%N<SUB>2</SUB> RF plasmas and afterglows have been generated in a quartz tube under a flowing condition maintained at 6-8 Torr and a flow rate of 0.5-0.6 slm. The detailed emission characteristics of active species have been analyzed by emission spectroscopy. Under such conditions, the plasma rotational temperature increases from 400 to 800 K with increasing RF powers from 50 to 130 W, while the characteristic vibrational temperature remains at about 10<SUP>4</SUP> K. The densities of active species (N, N<SUB>2</SUB>(A), N<SUB>2</SUB>(X, v > 13) and N<SUB>2</SUB><SUP>+</SUP>) in the afterglow are measured to be in the order of ~10<SUP>15</SUP>, ~10<SUP>11</SUP>, ~10<SUP>14</SUP> and ~10<SUP>10</SUP> cm<SUP>-3</SUP>, respectively. In addition, the following characteristics of the afterglows are noted: First, the same densities of the active species can be obtained at lower RF powers (20-50 W) for Ar-20%N<SUB>2</SUB> than for pure N<SUB>2</SUB> which requires higher RF powers (50-100 W). Second, the ionization degree of N<SUB>2</SUB><SUP>+</SUP>/N<SUB>2</SUB> in the plasma increases readily to a saturation value at a lower RF power of 50 W for Ar-20%N<SUB>2</SUB>, whereas in the afterglow, the absolute density of N<SUB>2</SUB><SUP>+</SUP> is further reduced below 10<SUP>9</SUP> cm<SUP>-3</SUP>.

The Hwarang Segi Manuscripts: An In-Progress Colonial Period Fiction

Ricard D. McBride II 한국학중앙연구원 한국학중앙연구원 2005 Korea Journal Vol.45 No.3

The Hwarang segi manuscripts, made public in 1989 and 1995, were purportedly discovered and copied by Bak Changhwa while working in Japan for the Japanese government between 1933 and 1945. Korean scholars are deeply divided on the issue of authenticity because the manuscripts are fundamentally different than the later Goryeo period sources that are presumed to have used Gim Daemun’s (fl. 704) Hwarang segi as a source. The manuscripts provide genealogies for historical figures that contradict the traditional sources. This study addresses two terms and titles deployed in the text that are anachronistic: pungwolju (lord of hwarang training/customs) and jeongtong (orthodox transmission). Pungwolju is not attested in other documents until the mid-Joseon period, and jeongtong and its associated terms were not used outside of the context of political legitimation until the early ninth century at earliest. Also, since Bak never publicized his putative discovery of the Hwarang segi during his lifetime, the evidence best suggests that the manuscripts represent drafts of an unfinished Sino-Korean fiction written by Bak during the colonial period.

Education as a Mirror of Spanish Society: Challenges and Policies towards Multiple Diversity

Ricard Zapata-Barrero Sookmyung institute for Multicultural Studies 2010 The Journal of Migration & Society Vol.1 No.2

Recent Developments in Health Appraisal and Life Extension of Mechanical Systems

Ricard S. Cowan,Ward O. Winer 한국트라이볼로지학회 1995 한국윤활학회지(윤활학회지) Vol.11 No.5

Education as a Mirror of Spanish Society

Ricard Zapata-Barrero 숙명여자대학교 아시아여성연구원 2010 OMNES: The Journal of Multicultural Society Vol.1 No.2

The ways in which the dominant cultural majority frames the educational system, determines perceptions of its own identity and understandings of the ‘other.’ In this article I take a political approach, by examining the management of cultural diversity within Spanish education policies, treating “education as the mirror of society”. This article analyzes Spanish challenges and policies approaches towards the management of immigration related diversity in education. The main finding is that there is not one approach, but several, due to both the decentralized character of the education system and the multiplicity of diversity that is at stake (i.e. language, religion, culture etc.).

Comparison of the Active Species in the RF and Microwave Flowing Discharges of N2 and Ar–20 %N2

Ricard, A.,Sarrette, J. P.,Oh, S. G.,Kim, Y. K. Springer Science + Business Media 2016 Plasma chemistry and plasma processing Vol.36 No.6

<P>We report a detailed comparison between RF and microwave (HF) plasmas of N-2 and Ar-20 %N-2 as well as in the corresponding afterglows by comparing densities of active species at nearly the same discharge conditions of tube diameter (5-6 mm), gas pressure (6-8 Torr), flow rate (0.6-1.0 slm) and applied power (50-150 W). The analysis reveals an interesting difference between the two cases; the length of the RF plasma (similar to 25 cm) is measured to be much longer than that of HF (6 cm). This ensures a much longer residence time (10(-2) s) of the active species in the N-2 RF plasma [compared to that (10(-3) s) of HF], providing a condition for an efficient vibrational excitation of N-2(X, v) by (V-V) climbing-up processes, making the RF plasma more vibrationally excited than the HF one. As a result of high V-V plasma excitation in RF, the densities of the vibrationally excited N-2(X, v > 13) molecules are higher in the RF afterglow than in the HF afterglow. Destruction of N-2(X, v) due to the tube wall is estimated to be very similar between the two system as can be inferred from the gamma(v) destruction probability of N-2(X, v > 3-13) on the tube wall (2-3 x 10(-3) for both cases) obtained from a comparison between the density of N-2(X, v > 3-9) in the plasmas to that of the N-2(X, v > 13) in the long afterglows. Interestingly enough, densities of N-atoms and N-2(A) metastable molecules in the afterglow regions, however, are measured to be very similar with each other. The measured lower density of N-2 (+) ions than expected in the HF afterglow is rationalized from a high oxygen impurity in our HF setup since N-2 (+) ions are very sensitive to oxygen impurity .</P>

Discharge source-dependent variation in the densities of active species in the flowing afterglows of N2 RF and UHF plasmas

Andre Ricard,Jean-Philippe Sarrette,전병욱,김유권 한국물리학회 2017 Current Applied Physics Vol.17 No.7

With a potential application to surface modification of oxide materials in mind, active species in RF and microwave (UHF) N2 afterglows were analyzed in our newly designed flowing reactors. For both plasma systems, discharge of N2 was generated in a long quartz tube with a small diameter (dia. 5e6 mm) and then was directly injected into a chamber with a large diameter of 15e20 cm. The discharge condition was set to be similar between the two systems; the gas pressure, flow rate and the applied power were 6 Torr, 0.6 slm and 100W, respectively. Under this condition, the residence time at the chamber inlet was (1e3) x 10『3 s. The RF and UHF afterglows were formed in the chamber with luminous jets from the end of the discharge tube. However, we found that the densities of active species were quite sourcedependent; N and N2(A) densities were higher in UHF than in RF in spite of more O-atoms impurity. The origin of such difference is also attributed to the inherent difference in the nature of excitation between the two plasma sources; RF is more vibrational and is longer than UHF.

Quantitative evaluation of the densities of active species of N2 in the afterglow of Ar-embedded N2 RF plasma

Andre Ricard,오수기,장중희,김유권 한국물리학회 2015 Current Applied Physics Vol.15 No.11

The N2 and Ar-20%N2 RF plasmas and afterglows have been generated in a quartz tube under a flowing condition maintained at 6e8 Torr and a flow rate of 0.5e0.6 slm. The detailed emission characteristics of active species have been analyzed by emission spectroscopy. Under such conditions, the plasma rotational temperature increases from 400 to 800 K with increasing RF powers from 50 to 130 W, while the characteristic vibrational temperature remains at about 104 K. The densities of active species (N, N2(A), N2(X, v > 13) and Nþ 2 ) in the afterglow are measured to be in the order of ~1015, ~1011, ~1014 and ~1010 cm3, respectively. In addition, the following characteristics of the afterglows are noted: First, the same densities of the active species can be obtained at lower RF powers (20-50 W) for Ar-20%N2 than for pure N2 which requires higher RF powers (50-100 W). Second, the ionization degree of N+ 2 =N2 in the plasma increases readily to a saturation value at a lower RF power of 50 W for Ar-20%N2, whereas in the afterglow, the absolute density of Nþ 2 is further reduced below 109 cm-3.

The role of active species in the N₂ and N₂-H₂ RF afterglows on selective surface nitriding of ALD-grown TiO₂ films

Wang, Yunfei,Ricard, Andre,Sarrette, Jean-Philippe,Kim, Ansoon,Kim, Yu Kwon Elsevier Sequoia 2017 Surface & coatings technology Vol.324 No.-

<P><B>Abstract</B></P> <P>We find that surface modification characteristics of TiO<SUB>2</SUB> using N<SUB>2</SUB> RF plasma are strongly dependent on the detailed composition of active species in the plasma and the afterglows. The surface nitriding of ALD-grown TiO<SUB>2</SUB> films in pure N<SUB>2</SUB> RF afterglows at room temperature (RT) is found to be more effective in the late afterglows than in the early afterglows. Adding a small fraction of H<SUB>2</SUB> in N<SUB>2</SUB> results in suppression of surface nitriding, suggesting that the change in the composition of the active species in the afterglows by H<SUB>2</SUB> is the origin to the suppressed nitriding performance. Here, we present our analysis on the surface chemical composition after the plasma modification as well as the densities of excited species such as N atoms, N<SUB>2</SUB>(A) and N<SUB>2</SUB>(X, <I>v</I>) metastable molecules and N<SUB>2</SUB> <SUP>+</SUP> ions in the afterglows of RF N<SUB>2</SUB> and N<SUB>2</SUB>–H<SUB>2</SUB> (<5%) at different positions along the downstream by emission spectroscopy. The early afterglow of N<SUB>2</SUB> changes from a pink to a late afterglow where the N+N recombination is the dominant process with the introduction of H<SUB>2</SUB>. The roles of active species such as N–atoms and N<SUB>2</SUB> <SUP>+</SUP> ions on TiO<SUB>2</SUB> surface nitriding are found to oppose to each other. We find that N atoms enhance the surface nitriding, while N<SUB>2</SUB> <SUP>+</SUP> ions are likely to deplete the surface-bound N species.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Surface nitriding of TiO<SUB>2</SUB> in the N<SUB>2</SUB> RF afterglow at RT is strongly dependent on the active species densities. </LI> <LI> High density of neutral N atoms plays a beneficial role in the surface nitriding of TiO<SUB>2</SUB>. </LI> <LI> The vibrationally excited N<SUB>2</SUB> and N<SUB>2</SUB> <SUP>+</SUP> species play a negative role in the surface nitriding performance. </LI> </UL> </P>

Determination of the vibrational, rotational and electron temperatures in N₂ and Ar–N₂ rf discharge

Britun, N,Gaillard, M,Ricard, A,Kim, Y M,Kim, K S,Han, J G Institute of Physics [etc.] 2007 Journal of Physics. D, Applied Physics Vol.40 No.4

<P>In order to characterize a nonequilibrium molecular plasma from the point of view of translational, vibrational and rotational degrees of freedom and their interaction, the characteristic temperatures of such a plasma were measured in an ICP rf reactor. Both pure nitrogen and argon–nitrogen mixture plasmas were examined for this purpose.</P><P>The experimental results of rotational (<I>T</I><SUB>r</SUB>), vibrational (<I>T</I><SUB>v</SUB>) and electron (<I>T</I><SUB>e</SUB>) temperatures are presented. Vibrational and rotational temperatures were measured as a function of nitrogen content for both E and H modes of ICP discharge using a power range of 45–200 W and pressure range of 2.6–13.3 Pa. Additionally, the pressure dependence of electron temperature in a pure nitrogen discharge was studied. Results show that rotational temperature is ≈370 K for E mode and ≈470 K for H mode and almost does not depend on either the applied rf power or the nitrogen content in the discharge. Vibrational temperature groups in the range 5000–12 000 K increase with applied rf power and constantly decay with an increase of nitrogen content. The measured values and behaviour of electron temperature are comparable with those for the positive column of the dc glow discharge. The results also prove that these three temperatures obey the classical inequality <I>T</I><SUB>e</SUB> > <I>T</I><SUB>v</SUB> > <I>T</I><SUB>r</SUB>, as well as clarifying the differences in both vibrational and rotational temperature for different modes of the ICP discharge.</P>