Reduction of the fast electrons preheating by changing the spike launch time in shock ignition approach Mohammad Jafar Jafari, Amir Hossein Farahbod and Somayeh Rezaei Eur. Phys. J. D, 70 1 (2016) 15 Published online: 21 January 2016 DOI: 10.1140/epjd/e2015-60477-8