Deceleration of fast ion rarefied beam due to Cherenkov interaction with ion-acoustic waves

The deceleration of a low-density beam of ions in plasma with developed ion-acoustic turbulence arising in strong electric field is described. The time and length of beam deceleration along and across the anisotropy axis of the wave number distribution of ion-acoustic waves are found. It is shown to what extent an increase in the strength of the electric field that generates turbulence is accompanied by a decrease in the time and length of braking. As the beam propagates along the anisotropy axis, its velocity decreases to approximately the velocity of ion sound, and the direction of propagation does not change. When the beam is decelerated with an initial velocity across the anisotropy axis, a velocity component appears along the anisotropy axis during deceleration, which results in the beam deflection from the initial direction. In this case, the modulus of the beam velocity at the end of deceleration is close to the ion sound velocity.

Figure 1

Change in beam velocity $u_z$ in time at $u_z\left(0\right)=5v_s$.

Figure 2

Change in beam velocity $u_z$ in space at $u_z\left(0\right)=5v_s$.

Figure 3

Change in beam velocity $u_{\perp }$ in time in the case of $u_{\perp }\left(0\right)=5v_s$.

Figure 4

Change in beam velocity $u_z$ in time in the case of $u_{\perp }\left(0\right)=5v_s$.

Figure 5

Change in beam velocity $u_{\perp }$ in space in the case of $u_{\perp }\left(0\right)=5v_s$.

Figure 6

Change in beam velocity $u_z$ in space in the case of $u_{\perp }\left(0\right)=5v_s$.