The interaction physics between energetic particle and plasma are introduced. The energy loss, range and pass-through time of energetic electron, proton, D, T or He in pure D plasma of 500 g/cm3 in density and 50 m in diameter at room temperature or 10 keV were calculated by Monte-Carlo method. The results show that, for electron, proton, D, T or He beam, the lowest beam intensity needed for edge(center) igniting is 363(458), 187(355), 13.1(24.8), 10.9(20.9) or 9.34(17.0) MA, respectively; the longest time for single particle to pass through plasma is 0.036(0.078), 0.219(0.569), 0.241(0.651), 0.320(0.854) or 0.228(0.592) ps, respectively. All the time above is below the fuel confinement time. Because of the Bragg peak of energy loss curve or higher energy loss, the end of particle range should be located in the heating zone to improve the heating efficiency and lower the bunch intensity needed for ignition. The lowest energy for ignition should be realized by increasing bunch intensity.