TY - JOUR T1 - Spectroscopic imaging of self-organization in high power impulse magnetron sputtering plasmas JF - Applied Physics Letters Y1 - 2013/07// SP - 054104 A1 - Joakim Andersson A1 - Pavel A Ni A1 - André Anders KW - Aluminium KW - ionization KW - Ionizing radiation KW - plasma ionization KW - visible spectra AB - Excitation and ionization conditions in traveling ionization zones of high power impulse magnetron sputtering plasmas were investigated using fast camera imaging through interference filters. The images, taken in end-on and side-on views using light of selected gas and target atom and ion spectral lines, suggest that ionization zones are regions of enhanced densities of electrons, and excited atoms and ions. Excited atoms and ions of the target material (Al) are strongly concentrated near the target surface. Images from the highest excitation energies exhibit the most localized regions, suggesting localized Ohmic heating consistent with double layer formation. VL - 103 IS - 5 JO - Appl. Phys. Lett. DO - 10.1063/1.4817257 ER -