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		| Paper: | 
		Structure and Evolution of Magnetic Fields Leading to Solar Flares | 
	 
	
		| Volume: | 
		369, New Solar Physics with Solar-B Mission | 
	 
	
		| Page: | 
		449 | 
	 
	
		| Authors: | 
		Wang, H. | 
	 
	
	
		| Abstract: | 
		In this paper, I review the observations of preflare magnetic conditions. The following topics will be discussed: (1) Static non-potential magnetic topology before flares, such as high magnetic gradient, strong magnetic shear and large twist and electric current. (2) Dynamic pre-flare conditions such as new flux emergence, helicity injection and shear/converging flows. (3) The evolution of these magnetic structures leading to and following flares. Unprecedented vector magnetograms from Solar-B, with high resolution, cadence, stability, will certainly make breakthroughs in this research area. | 
	 
	
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