- 學位論文
常壓氬氣及氬氣/氧氣電漿模型與介電層 影響之研究
Modeling Study of Atmospheric Ar , Ar/O2 Glow Discharge and Dielectric Layer Effect
摘要
本研究針對平板式常壓Ar/O2輝光放電建立數學模型及反應機構，探討 不同的製程操作參數對電漿中之主要反應物種濃度之影響，除了明瞭常壓 Ar/O2輝光放電在不同條件下之主要反應機制，並可得知電漿物種之組成。 首先建立零維模型，模擬中頻激發之常壓電漿，發現在常壓下純Ar電漿 之主要離子為Ar2 +，在Ar電漿中添加氧氣後，電子密度會隨之下降，電子溫 度卻有先升後持平之趨勢，O2 +與O2 -則隨之增加且成為Ar/O2電漿中之主要 正、負離子。 第二部份是一維模型，以模擬低頻脈衝電場下激發之常壓電漿，發現電 子溫度在電場on與off時之攀升及下降之變化速率非常迅速(其變化時間約 為10-8秒)。電漿物種組成之變化趨勢與零維模型計算結果相同。當氧氣添 加至電漿中，電子密度在整個循環時間會下降，且同時會提高電漿之陰電 性，在電子溫度方面，發現氧氣添加量增加會使得電場強度與電漿陰電性 增強(因功率固定)，使電子溫度在氧氣添加的越多時，其爬升至穩定的速度 越快。 最後以一維模型為基礎在上電極處添加介電層，使電漿變成介電層放 電系統，發現脈衝式之介電電漿(相對於脈衝式電漿與連續式介電電漿)其 在相同電漿功率(10W)下具有較高之電漿強度，因此時外部電壓也較大。
並列摘要
In this study, two mathematical models for Ar/O2 APGD was developed: A zero-dimensional model for medium-frequency APGD, and one-dimensional model for pulsed-powered APGD. The influence of power and oxygen fraction on the plasma characteristics is investigated by the developed model. The effect of dielectric later plasma characteristic is also studied in the one-dimensional. The main reaction pathway in Ar and Ar/O2 atmospheric plasma was realized by the rate-of-production analysis. The zero-dimensional plasma model shows that the main active species in Ar atmospheric plasma include metastable dimer argon molecules (Ar2*), dimer argon ions (Ar2 +), and electron (e). It was found that O2 + & O2 - become the major ionic species, when 1% O2 is added to Ar plasma. And O2 addition also reduces electron and Ar metastable density, and generates copious amounts of ozone. In one-dimensional plasma model, the addition of oxygen significantly reduces metastable species density. The electron temperature first decreases then increases when oxygen fraction is increased. The dielectric layer plasma model show that the system with dielectric layer can generate more electrons and have a high average electron temperature than that without dielectric layer under the same input power. The discharge voltage significantly reduces when dielectric layer is added into atmospheric plasma system.