Plasma photography offers a captivating glimpse into the intricate dynamics of magnetic confinement systems. These images, produced from a single processed imaged of a titanium planar cathode, reveal the underlying processes that shape the plasma's behavior. Original lmage, left: The initial image showcases a vibrant blue-white glow, primarily attributed to the light emission from sputtered titanium. The i intensity off this glow correlates with the rate Of sputtering, With brighter regions indicating higher levels ofr material removal. A subtle pinkish-purple hue, visible in/ areas of lower titanium emission in the turnarounds, is due to argon light emission, suggesting reduced sputtering in those regions. Overall, the plasma appears relatively uniform when highly intense.
Enhanced Contrast: By deepening the image's blacks, the shape of the higher-intensity plasma becomes more pronounced. A clear counterclockwise pattern emerges, indicative of the Hall current electron motion. The reduced plasma intensity in the upper left and lower right portions of the racetrack corresponds to regions of lower Hall current, where electron loss occurs in the turnarounds. This is knows as the Cross-Corner effect. Focused on Shape: Further emphasis on the plasmas shape reveals variations h its width along the straightaways. These fluctuations arise from the additive and subtractive effects of electron current density along the magnetic confinement. Electrons, traveling counterclockwise, ionize argon and sputter target material, releasing secondary electrons into the strongest magnetic fields near the target surface. This process enhances ionization efficiency as electrons progress down the left racetrack. The plasma reaches maximum width near1 the center of the left : straightaway, influenced by factors such as magnetic field strength, operating pressure, and target material's secondary electron emission The resulting plasma intensity closely mirrors the expected erosion profile on the target.
Filtered View: By applying additional filtering, the tapered growth of plasma in each straightaway and its partial exten sion into the turnarounds becomes strikingly clear. he bright section in the lower left straightaway represents a region where electrons are pushed into weaker magnetic fields, reducing ionization efficiency beyond that point. However, this process also carries more electrons into the bottom turnaround, slightly increasing its plasma intensity. Conversely,the right-hand straightaway starts with fewer electrons in the Hall current.
These images offer a fascinating visual representation off the complex interplay between various factors that govern plasma behaviori inr magnetic confinement systems. By analyzing images like this and comparing them to COMSOL Simulations Arizona Thin Film Research can help you gain valuable insights into optimizing you sputtering performance.
