• 한국입자에어로졸학회지
• /
• 제5권3호
• /
• pp.123-131
• /
• 2009

This paper presents simulation results of particle transport in low-pressure, low-temperature plasma environment. The size dependent transport of particles in the plasma is investigated with a two-dimensional simulation tool developed in-house for plasma chamber analysis and design. The plasma model consists of the first two and three moments of the Boltzmann equation for ion and electron fluids respectively, coupled to Poisson's equation for the self-consistent electric field. The particle transport model takes into account all important factors, such as gravitational, electrostatic, ion drag, neutral drag and Brownian forces, affecting the motion of particles in the plasma environment. The particle transport model coupled with both neutral fluid and plasma models is simulated through a Lagrangian approach tracking the individual trajectory of each particle by taking a force balance on the particle. The size dependant trap locations of particles ranging from a few nm to a few ${\mu}m$ are identified in both electropositive and electronegative plasmas. The simulation results show that particles are trapped at locations where the forces acting on them balance. While fine particles tend to be trapped in the bulk, large particles accumulate near bottom sheath boundaries and around material interfaces, such as wafer and electrode edges where a sudden change in electric field occurs. Overall, small particles form a "dome" shape around the center of the plasma reactor and are also trapped in a "ring" near the radial sheath boundaries, while larger particles accumulate only in the "ring". These simulation results are qualitatively in good agreement with experimental observation.

• 산업기술연구
• /
• 제26권B호
• /
• pp.173-181
• /
• 2006

We analyzed systematically particle growth in the pulsed $SiH_4$ plasmas by a numerical method and investigated the effects of pulse modulations (pulse frequencies, duty ratios) on the particle growth. We considered effects of particle charging on the particle growth by coagulation during plasma-on. During plasma-on ($t_{on}$), the particle size distribution in plasma reactor becomes bimodal (small sized and large sized particles groups). During plasma-off ($t_{off}$), there is a single mode of large sized particles which is widely dispersed in the particle size distribution. During plasma on, the large sized particles grows more quickly by fast coagulation between small and large sized particles than during plasma-off. As the pulse frequency decreases, or as the duty ratio increases, $t_{on}$ increases and the large sized particles grow faster. On the basis of these results, the pulsed plasma process can be a good method to suppress efficiently the generation and growth of particles in $SiH_4$ PCVD process. This systematical analysis can be applied to design a pulsed plasma process for the preparation of high quality thin films.

• 한국세라믹학회지
• /
• 제53권1호
• /
• pp.93-98
• /
• 2016

Cold plasma and heat treatment were selected as technologies to reduce unburned carbon in fly ash to less than 1.0%. Both cold plasma and heat treatment made it possible to eliminate unburned carbon to less than 1.0%. In the case of fly ash, which almost entirely eliminated unburned carbon with an ignition loss of 0.5%, heat treatment caused adhesion among particles and the BET specific surface area rapidly decreased as the mean particle size increased. On the other hand, with cold plasma, unburned carbon elimination caused the BET specific surface area to decrease and, as no adhesion occurred among particles, the mean particle size became small. Also, cold plasma treatment allowed small spherical particles confined within the unburned carbon particles to be released with the elimination of the unburned carbon frame, so that the quantity of fine particles had a tendency to slightly increase.

• 반도체디스플레이기술학회지
• /
• 제2권4호
• /
• pp.9-12
• /
• 2003

This paper describes a newly developed simulation environment for analysis and design of a plasma processing chamber based on first principles including complicated physical and chemical interactions of plasma, fluid dynamics of neutrals, and transport phenomena of particles. Capabilities of our simulator, named VIP-SEPCAD (Virtual Integrated Prototyping Simulation Environment for Plasma Chamber Analysis and Design), are demonstrated through a two dimensional simulation of an oxygen plasma chamber. VIP-SEPCAD can provide plasma properties such as spatiotemporal profiles of plasma density and potential, electron temperature, ion flux and energy, etc. By coupling neutral and particle transport models with a three moment plasma model, VIP-SEPCAD can also predict spatiotemporal profiles of chemically reactive species and particles exist in plasma.

• 한국산업융합학회 논문집
• /
• 제7권1호
• /
• pp.115-120
• /
• 2004

An indoor air cleaner consisting of a dielectric barrier discharge system and an electrostatic precipitator (ESP) was experimentally investigated. The function of the dielectric barrier discharge is to precharge particles by producing nonthermal plasma before indoor air enters ESP, leading to an enhancement in dust collection efficiency. The dependence of particle size distribution on the plasma discharge was examined to understand the mechanism of the particle precharging. The plasma discharge was found to increase the electrical force of the particles, rather than agglomerate them. Coarse particles in the range of 0.5 to $5.0{\mu}m$ were observed to be easily collected by this indoor air cleaner, and the present study laid emphasis on the removal of fine particles of $0.3{\mu}m$. The collection efficiency of the fine particles was largely enhanced by the plasma discharge.

• 조명전기설비학회논문지
• /
• 제18권1호
• /
• pp.52-59
• /
• 2004

미립자 플라즈마란 입경이 수[$\mu\textrm{m}$]이하의 거의 일정한 크기를 가진 미립자가 다수로 생성 및 유지되면서, 정 또는 부외 전하를 가지고 기체 플라즈마 중에 부유하는 상태를 말한다. 플라즈마 프로세스에서는 이러한 미립자가 집적회로에 중착되어 막의 열화, 회로 배선의 불량 및 단선 등의 약영향을 끼치는 것으로 인식되고 있으며, 이러한 부분에 대한 억제나 제어에 관한 연구가 진행되고 있다. 본 연구에서는 유체 모델을 이용한 시뮬레이션으로부터 방전 챔버내의 Ar 플라즈마의 현상을 이해하고, Ar 플리즈마 중에 미립자를 투입하여 그 움직임을 분석하여, 플라즈마 중의 미립자 운동의 핵석 결과로서는, 하부 전극 면위에 비교적 규칙성을 갖는 미립자가 배열하는 것을 확인할 수 있었다. 또한, 약 전리 플라즈마에서는 전지의 이동로가 크기 때문에 미립자의 대전량은 평균 전자 에너지에 크게 의존하는 것을 알 수 있었다.

• 전기학회논문지P
• /
• 제65권3호
• /
• pp.216-218
• /
• 2016

In this study, we used not chemical and physical synthesis method but the solution plasma sputtering method in the synthesis of silver nano-particles. Synthesis of all the silver nano-particles was conducted for 1hour in 360 ml of distilled water and characteristics of changing the input voltage and frequency of the synthesised silver nano-particles by using the solution plasma sputtering method were analyzed through FE-SEM(Field Emission-Scanning Electron Microscope). We changed the input voltage from 8 kV to 10 kV in steps of 1 kV, input frequency from 20 kHz to 30 kHz in steps of 5 kHz in the solution plasma reactor with the advanced device which can control the DC voltage and frequency. We confirmed that the size of silver nano-particles were larger according to the change of the input voltage and frequency.

• 한국진공학회지
• /
• 제9권2호
• /
• pp.172-178
• /
• 2000

반도체 제조공정 중 플라즈마 반응기 내에서 입자오염을 유발하는 입자들의 거동과 성장을 모델식을 사용하여 이론적으로 고찰하였다. 플라즈마 반응기 내에서 입자 거동에 영향을 미치는 힘들로 유체 대류, 입자 확산 및 외부힘 (ion drag force, electrostatic force, 중력) 등을 고려하였다. 플라즈마 벌크 영역에서 전하를 가진 입자들간의 충돌에 의한 입자 성장을 고려하기 위해 모델식에 입자 전하 분포를 고려하였다. 대부분의 입자들은 ion drag force와 electrostatic force가 균형을 이루고 있는 두 sheath 경계 영역에 존재하였으며 두 sheath 영역과 벌크 플라즈마에서의 입자 농도는 0에 접근하였다. 시간이 지남에 따라 입자 충돌로 인한 입자들의 크기는 증가하였으며 입자가 성장함에 따라 입자 표면적의 증가와 더불어 입자가 가지는 평균 전하량도 증가하였다.

• 센서학회지
• /
• 제15권4호
• /
• pp.284-290
• /
• 2006

This study uses neon, xenon, and helium gas mixture microdischarge to determine the effects of priming particles on the neon emission characteristics in an alternate current plasma display panel (AC PDP). The infrared (823 nm) and neon emission (585 nm) intensities are measured and compared in the blue cells in the case of new discharge with priming particles or conventional discharge without priming particles, respectively. It is found that the priming particles can produce a plasma discharge effectively even under the weak electric field condition, thereby resulting in reducing the neon emission intensity remarkably without sacrificing the IR emission intensity. As a result, it is found that the Ne emission intensity is reduced by about 46.4 % but the blue visible emission intensity is increased by about 15.2 % when compared with the conventional discharge without priming particles.

• Nuclear Engineering and Technology
• /
• 제51권7호
• /
• pp.1860-1865
• /
• 2019

The confinement degradation of the energetic particles during RMP would be a key issue in success of realizing the successful energy production using fusion plasma, because a 3.5 MeV energetic alpha particle should be able to sustain the burning plasma after the ignition. As KSTAR recent results indicate the generation of high-performance plasma(${\beta}_p{\sim}3$), the confinement of the energetic particles is also an important key aspect in neutral beam driven plasma. In general, the measured absolute value of the neutron intensity is generally used for to estimating the confinement time of energetic particles by comparing it with the theoretical value based on transport calculations. However, the availability of, but for its calculation process, many accurate diagnostic data of plasma parameters such as thermal and incident fast ion density, are essential to the calculation process. In this paper, the time evolution of the neutron signal from an He3 counter during the beam blank has permitted to facilitate the estimation of the slowing down time of energetic particles and the method is applied to investigate the fast ion effect on ELM suppressed KSTAR plasma which is heated by high energy deuterium neutral beams.