International Science Community Association Research Journal of Recent Sciences 2277 - 2502 1 1 2012 January 2 Electron Density Measurement in an Active Region observed By Extreme Ultraviolet Imaging Spectrometer (EIS) on Hinode 40 45 EN Gwal A.K. 1 Space Science Laboratory, Department of Physics Barkatullah University Bhopal-462026, INDIA Jain SantoshKumar 2 Panda Gopal 3 Gujar Y.S. 4 Raghuwanshi S. 5 S.K. Vijay 6 Bora Abhijit 1 Tezpur University, Napaam, Sonitpur district, Assam, INDIA Parikh AnkitaN. 1 Department of Zoology, Faculty of Science, The Maharaja Sayajirao University of Baroda, Varodara.390 002, Gujarat, INDIA Mankodi P.C. 2 SenthilKumar A.P. 1 Department of Mechanical Engineering PSG College of Technology, Coimbatore, INDIA Karthikeyan P. 2 Department of Automobile Engineering PSG College of Technology, Coimbatore, INDIA V. PrabhuRaja 3 M. Ramu 4 Somasundharam S. 5 Vasudevan V. 6 Selvakumar B. 1 Department of Mechanical Engineering PSG College of Technology, Coimbatore, INDIA V. PrabhuRaja 2 Department of Automobile Engineering PSG College of Technology, Coimbatore, INDIA R. NandhaKumar 3 SenthilKumar A.P. 4 M.S. Vignesh 5 G.R. VivekSharma 6 Karthikeyan P. 7 Kumar Pradeep 1 Department of Physics, K G K (P G) College, Moradabad 244 001, Uttar Pradesh, INDIA Singh Bhupendra 2 Department of Physics, Hindu College, Moradabad 244 001, Uttar Pradesh, INDIA Kumar Anil 3 > Research Paper 2011 9 30 2012 January 2 Active regions are the brightest features seen on the Sun’s surface when observing in ultra-violet and X-rays. They are the structures of complex magnetic topology and most of the high energy explosions such as flares and coronal mass ejections (CMEs) originate from active regions. The Extreme-ultraviolet Imaging Spectrometer (EIS) on board Hinode provides an excellent opportunity to study the physical plasma parameters in spatially resolved coronal structures. Using spectral observations performed over an active region on February 07, 2007 with the EIS spectrometer on Hinode, we study the density structure at different temperatures. To analyze the density structure we compare density ratios of a series of iron lines Fe XII 186.88 Å , Fe XII 195.12 Å, Fe XIII 202.04 Å, Fe XIII 203.82 Å, Fe XIV 264.79 Å and Fe XIV 274.20 Å observed by the Hinode/EUV Imaging Spectrometer (EIS). We found that the electron density in the observed active region (AR 10940) varies from 10-1012 cm-3 and is highest in the core of this active region. Copyright@ International Science Community Association