Quantum Electron-Exchange Effects on the Buneman Instability in Quantum Plasmas

Hong, Woo-Pyo,Jamil, Muhammad,Rasheed, Abdur,Jung, Young-Dae De Gruyter 2015 Zeitschrift für Naturforschung. A, A journal Vol.70 No.6

<P><B>Abstract</B></P><P>The quantum-mechanical electron-exchange effects on the Buneman instability are investigated in quantum plasmas. The growth rate and wave frequency of the Buneman instability for the quantum plasma system composed of the moving electron fluid relative to the ion fluid are obtained as functions of the electron-exchange parameter, de Broglie’s wave length, Debye’s length, and wave number. The result shows that the electron-exchange effect suppresses the growth rate of the quantum Buneman instability in quantum plasmas. It is also shown that the influence of electron exchange reduces the instability domain of the wave number in quantum plasmas. However, the instability domain enlarges with an increase in the ratio of the Debye length to the de Broglie wave length. In addition, the electron-exchange effect on the growth rate of the Buneman instability increases with an increase in the ratio of the Debye length to the de Broglie wave length. The variation in the growth rate of the Buneman instability due to the change in the electron-exchange effect and plasma parameters is also discussed.</P>

Quantum Shielding Effects on the Eikonal Collision Cross Section in Strongly Coupled Two-temperature Plasmas

Lee, Myoung-Jae,Jung, Young-Dae De Gruyter 2017 Zeitschrift für Naturforschung. A, A journal Vol.72 No.5

<P><B>Abstract</B></P><P>The influence of nonisothermal and quantum shielding on the electron-ion collision process is investigated in strongly coupled two-temperature plasmas. The eikonal method is employed to obtain the eikonal scattering phase shift and eikonal cross section as functions of the impact parameter, collision energy, electron temperature, ion temperature, Debye length, and de Broglie wavelength. The results show that the quantum effect suppresses the eikonal scattering phase shift for the electron-ion collision in two-temperature dense plasmas. It is also found that the differential eikonal cross section decreases for small impact parameters. However, it increases for large impact parameters with increasing de Broglie wavelength. It is also found that the maximum position of the differential eikonal cross section is receded from the collision center with an increase in the nonisothermal character of the plasma. In addition, it is found that the total eikonal cross sections in isothermal plasmas are always greater than those in two-temperature plasmas. The variations of the eikonal cross section due to the two-temperature and quantum shielding effects are also discussed.</P>

Influence of Electron Exchange and Quantum Shielding on the Elastic Collisions in Quantum Plasmas

Lee, Gyeong Won,Jung, Young-Dae Verlag der Zeitschrift für Naturforschung 2013 Zeitschrift für Naturforschung. A, A journal Vol.68 No.10

<P>The influence of electron exchange and quantum shielding on the elastic electron-ion collision is investigated in degenerate quantum plasmas. The second-order eikonal method and effective screened potential are employed to obtain the scattering phase shift and collision cross section as functions of the impact parameter, collision energy, electron-exchange parameter, Fermi energy, and plasmon energy. It is found that the electron-exchange effect enhances the eikonal scattering phase shift as well as the eikonal collision cross section in quantum plasmas. The maximum position of the differential eikonal collision cross section is found to be receded from the collision center with an increase of the electron-exchange effect. It is interesting to note that the influence of the electron exchange on the eikonal collision cross section decreases with increasing collision energy. It is also found that the eikonal collision cross section decreases with an increase of the plasmon energy and, however, increases with increasing Fermi energy.</P>

Nonlinear excitation of large-amplitude ion acoustic solitary waves in a multispecies warm ion plasma with ultra-relativistic degenerate electrons

Kumar Kishan,Mishra M. K. 한국물리학회 2022 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.80 No.2

Large-amplitude ion acoustic solitons (IASs) in an ultra-relativistic degenerate quantum plasma consisting of non-degenerate warm light nuclei, stationary heavy nuclei and relativistically degenerate electrons are investigated. The Sagdeev’s pseudopotential approach is adopted to obtain the energy integral equation for the study large-amplitude IASs. The Mach number domain (M l ≤ M ≤ M h) is determined numerically in term of various parameters. Our numerical investigation shows that only compressive solitary waves can propagate in present plasma systems. The effect of different plasma parameters, such as the number density ( μe ), degenerate electron density ( k ), relativistic factor ( γ ), temperature ratio ( σ ) and Mach number ( M ), on the characteristic properties of solitary waves are reported. The corresponding phase trajectory is also drawn for the existing domain. The present theoretical study recovers the results from a previously published article (Sultana and Schlickeiser, Phys. Plasmas 25: 022110, 2018) for a cold multi-ion quantum plasma. Our result may be helpful to understand the basic characteristic of nonlinear solitary waves propagating in a quantum plasma, in which the non-degenerate warm light nuclei, stationary heavy ions and relativistic degenerate electrons are present. Plasmas with the given composition are found in astrophysical object such as white dwarfs, neutrons stars, etc.

양자 플라스마 내의 전자-이온 제동복사 현상에 대한 전자-교환 효과

심재원,정영대 한국물리학회 2014 새물리 Vol.64 No.2

본 논문에서는, 양자 플라스마 내에서 제동복사 현상에 작용하는 전자-교환 효과를 연구하였다. 진동 Shukla-Eliasson 유효 퍼텐셜과 충돌변수 방법을 이용하여 강한 양자 되튐 현상에서의 전자-이온간 제동복사 산란 단면적을 충돌 변수, 광 에너지, 입사 에너지, 전자 교환 변수, 페르미 에너지, 그리고 플라스몬 에너지의 함수로 구하였다. 본 연구를 통하여 전자 교환 효과는 GaAs 반도체 양자 플라스마 내에서의 제동복사 산란 단면적을 증가시킴을 밝혀내었다. 그리고 전자-교환 효과가 충돌 변수의 증가에 따라 제동복사 스펙트럼이 증가하는 것을 규명하였다. 그리고 제동복사 스펙트럼에 작용하는 전자-교환 효과는 페르미 에너지가 증가함에 따라 증가하나 플라스몬 에너지가 증가함에 따라서는 감소하는 것을 밝혀내었다. The electron-exchange effects on the bremsstrahlung process are investigated in quantum plasmas. The oscillatory Shukla-Eliasson effective potential and the impact-parameter method are employed to obtain the electron-ion bremsstrahlung radiation cross section for strong quantum recoil cases as a function of the impact parameter, photon energy, projectile energy, electron-exchange parameter, Fermi energy, and plasmon energy. The result shows that the electron-exchange effect enhances the bremsstrahlung cross section in GaAs semiconductor quantum plasmas. The effect of electron exchange on the bremsstrahlung spectrum is found to increase with increase impact parameter. In addition, that effect is found to increase with increasing Fermi energy and to decrease with increasing plasmon energy.

A facile synthesis of bimetallic AuPt nanoparticles as a new transparent counter electrode for quantum-dot-sensitized solar cells

Dao, Van-Duong,Choi, Youngwoo,Yong, Kijung,Larina, Liudmila L.,Shevaleevskiy, Oleg,Choi, Ho-Suk Elsevier 2015 Journal of Power Sources Vol.274 No.-

<P><B>Abstract</B></P> <P>This study first reports the synthesis of AuPt bimetallic nanoparticles (AuPt-BNPs) on an FTO glass substrate using dry plasma reduction (DPR) and its application as an alternative transparent counter electrode (CE) for quantum-dot-sensitized solar cells (QDSCs) operated under bi-side illumination. DPR is an economically feasible and ecologically sustainable method. The formation of ultrafine crystalline AuPt-BNPs on an FTO substrate is confirmed through TEM, HRTEM with HAADF-STEM and HAADF-STEM-EDS analyses. The mechanism for controlling the size, mono-dispersity, and areal number density of nanoparticles on the substrate surface is suggested. The CE fabricated with AuPt-BNPs exhibits a high electro-catalytic activity without losing the optical transmittance of the FTO substrate. The QDSC employing the AuPt-BNP electrode reaches efficiencies of 2.4% under front-side illumination and 2.2% under back-side illumination. Bi-side illumination yields an efficiency of 3.4%, which is comparable to an efficiency of 3.7% obtained for the QDSC with the state-of-the-art CE.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An ultrafine crystalline AuPt-BNP electrode was successfully fabricated using DPR. </LI> <LI> The formation mechanism of BNPs provides a way for tuning catalyst morphology. </LI> <LI> The BNPs show high catalytic activity without reducing the optical transmittance. </LI> <LI> Bi-side illumination yields 3.4% efficiency comparable to 3.7% of Au-sputtered CE. </LI> <LI> The proposed method can be a key technique for efficient and transparent QDSCs. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Influence of the Dynamic Quantum Shielding on the Transition Bremsstrahlung Spectrum and the Gaunt Factor in Strongly Coupled Semiclassical Plasmas

Jung, Young-Dae,Hong, Woo-Pyo Verlag der Zeitschrift für Naturforschung 2013 Zeitschrift für Naturforschung. A, A journal Vol.68 No.1

<P>The influence of the dynamic quantum shielding on the transition bremsstrahlung spectrum is investigated in strongly coupled semiclassical plasmas. The effective pseudopotential and the impact parameter analysis are employed to obtain the bremsstrahlung radiation cross section as a function of the de Broglie wavelength, Debye length, impact parameter, radiation photon energy, projectile energy, and thermal energy. The result shows that the dynamic screening effect enhances the transition bremsstrahlung radiation cross section. It is found that the maximum position of the transition bremsstrahlung process approaches to the center of the shielding cloud with increasing thermal energy. It is also found that the dynamic screening effect on the bremsstrahlung radiation cross section decreases with an increase of the quantum character of the semiclassical plasma. In addition, it is found that the peak radiation energy increases with an increase of the thermal energy. It is also found that the dynamic quantum screening effect enhances the bremsstrahlung Gaunt factor, especially for the soft-photon case.</P>

Two strategies to enhance efficiency of PbS quantum dot solar cells: Removing surface organic ligands and configuring a bilayer heterojunction with a new conjugated polymer

Nam, M.,Lee, T.,Kim, S.,Kim, S.,Kim, S.W.,Lee, K.K. Elsevier Science 2014 ORGANIC ELECTRONICS Vol.15 No.2

We present two novel techniques for improving the efficiency of PbS quantum dot (QD) solar cells. First, plasma was applied to QD film with the aim of removing surface organic ligands, and then the chemical and optical properties of the QDs were investigated. Second, a thin layer of conjugated polymer was then deposited on top of the plasma-treated PbS QD film as a transportation layer for holes. The charge separation and subsequent transfer dynamics were examined, as were the resultant photovoltaic characteristics, according to the kind of polymer used. The developed device, which comprises a bilayer heterojunction of plasma-treated PbS QDs and poly[2,6-(4,4'-bis(2-ethylhexyl)dithieno[3,2-b:2',3'-d]silole)-alt-4,7(2,1,3-benzothiadiazole)] (PSBTBT), showed not only broad-range absorption of the solar spectrum, but also high charge transfer efficiency prior to recombination. This results in a largely increased power conversion efficiency (PCE) of 1.76%, compared to the 0.7% value of a PbS QD-only device not subjected to plasma treatment. This indicates that the proposed techniques are very useful for improving the efficiency of inorganic QD-based solar cells.

Karpman–Washimi Ponderomotive Magnetization and Radiated Power: Streaming and Resonant Effects

Ki, Dae-Han,Jung, Young-Dae Verlag der Zeitschrift für Naturforschung 2013 Zeitschrift für Naturforschung. A, A journal Vol.68 No.6

<P>The electron streaming and resonance effects on the non-stationary Karpman-Washimi nonlinear ponderomotive magnetization and radiated power are investigated in a quantum plasma. The ponderomotive Karpman-Washimi magnetization and radiation power due to the ponderomotive force are obtained as functions of the electron streaming velocity, Fermi velocity, wave frequency, and wave number. In small wave numbers, it is found that the electron streaming effect enhances the Karpman-Washimi ponderomotive magnetization. It is found that the electron streaming effect shifts the resonant wave number to the smaller wave number domain. It is also found that the quantum effect reduces the electron streaming velocity for the ponderomotive magnetization near the resonant wave number. In addition, the wave frequency for the resonant Karpman-Washimi radiated power is found to be increased with increasing wave number.</P>

The Effects of Oxygen Plasma and Cross-link Process on Quantum-dot Light Emitting Diodes

Nam-Kwang Cho,Seong Jun Kang 한국진공학회 2014 한국진공학회 학술발표회초록집 Vol.2014 No.2