From kusano@hiroshima-u.ac.jp Tue May 27 17:53:26 2003 Date: Sat, 17 May 2003 12:57:31 +0900 From: Kanya Kusano To: 'Kanya Kusano' , 'Jongchul Chae' Cc: 'Pascal Demoulin' , 'mitch Berger' , 'Pablo Mininni' , 'Richard Canfield' , 'Alexander Nindos' , 'BC Low' , 'Jim Klimchuk' , 'Marcelo Lopez-Fuentes' , 'Sarah Gibson' , sakurai@solar.mtk.nao.ac.jp, 'Terry Forbes' , "'Brian T. Welsch'" , dana@mithra.physics.montana.edu, magara@mithra.physics.montana.edu, apevtsov@nso.edu, haimin@sundog.caltech.edu, yjmoon@bbso.njit.edu, "[iso-2022-jp] '?^[$B;3^[(B ^[$B1{L@^[(B'" Subject: RE: 2 new papers on magnetic helicity [The following text is in the "iso-2022-jp" character set] [Your display is set for the "US-ASCII" character set] [Some characters may be displayed incorrectly] Sorry !! replace my last mail with this, Thanks! ---------------------------------------------------------------------------- ----------------- Hello Chae-san! Thanks for your note. It was well written, and very helpful for me. I like to confirm with you about that I concerned not only a very rare case such that a very long-length flux emerges. Let’s suppose that the simplest potential field, Bx=0, By = B_0 cos (ky) exp(-kz) Bz = -B_0 sin(ky) exp(-kz), emerges by a rigid body motion V=(0,0,Vz), where z denotes the altitude from the photosphere. Then, the LCT velocity diverges to infinity Uy = (By/Bz) Vz = cot(ky) Vz. It indicates that the infinite velocity arises always when the magnetic flux (integrated over each polarity) changes, and we have to detect that in order to measure the helicity and energy fluxes due to the flux emerging. I know that it is a "quantitative" issue rather than a theoretical problem. However, therefore, we should check that quantitatively. As I wrote at the last mail, it is a necessary condition for Demoulin & Berger’s method to work well that the residual R = dBn/dt + nabla.(B_n Ut) is negligibly small everywhere. I guess that you also can measure that, and I recommend you to do it. Anyway, it is my pleasure to talk with you, and I hope to keep contact with you. The distance between us is very close not only in science but also geographically! Best regards, Kanya -------------------------------------------------------- Kanya KUSANO, Graduate School of Advanced Sciences of Matter, Hiroshima University Higashi-Hiroshima, Hiroshima 739-8530, Japan Phone:[81] (824) 24-7016 fax: [81] (824) 24-7014 e-mail: kusano@hiroshima-u.ac.jp home page: http://plasma.sci.hiroshima-u.ac.jp/~kusano/ --------------------------------------------------------