Spatiotemporal dynamics of ultrarelativistic beam-plasma instabilities

Ion effects on the scaling of magnetic field amplification in plasmas with the system size

“…The scaling of the magnetic field amplification with the system size for the case of movable ions is also confirmed with three-dimensional (3D) PIC simulations, using the code EPOCH [39] directions. Different from the transverse 2D simulations, the system is initially dominated by the oblique two-stream instability [28,36] (i.e. the coupled two-stream and CFI) in the 3D simulations, as the chevron-shaped pattern imprinted on the beam density profile shown in figure 9(a).…”

“…Time evolutions of the transverse magnetic field energy E B ⊥ and beam electron energy E be are shown in figure 2 for the two plasma cases. The growth rate of the instability is [12,28,36,37], where β = v be0 /c, α is the beam-to-plasma density ratio, as indicated in figure 2(a). Good agreement is found between the theory and simulation results.…”

“…Moreover, the spatiotemporal dynamics of the oblique two-stream instability (i.e. the mixed mode between two-stream and CFI) were investigated with theory and PIC simulations, taking into account the effects of finite beam length and radius [20,28]. Experimental investigations of CFI were also performed in the laboratory with accelerator electron beam [29] and the beam from laser-plasma interactions [30][31][32][33].…”

Channeling acceleration in crystals and nanostructures and studies of solid plasmas: new opportunities

“…What is left to the plasma response is the return current that flows through the beam, and leads to an unstable counterstreaming system of beam and plasma electrons, where any perturbation at the scale of 𝜆 𝑝 can grow exponentially as the beam propagates through the solid. For ultrarelativistic beams such as delivered by FACET-II, two modes of instability are prominent: the oblique two-stream instability (OTSI) [23], which is mainly electrostatic and with a wave vector at an oblique angle with respect to the beam propagation, and the current filamentation instability (CFI), which is mainly magnetic and transverse. This is exemplified in figure 3 showing the FACET-II electron beam after 0.7 mm The simulation was run using the 3D PIC code [24], with a peak beam density 𝑛 𝑏 = 1 × 10 20 cm −3 , a normalized transverse emittance of 3 mm mrad, a bunch length of 1 µm and with periodic boundary conditions in the transverse directions.…”

“…propagation through aluminum, as simulated using the 3D PIC code [24]. At the front of the beam (right of figure 3), longitudinal and transverse modulations are clearly observed and correspond to the OTSI instability, which is the fastest mode to grow in the linear phase [23]. In contrast, at the rear of the beam, beam filaments can be identified and attributed to the CFI instability.…”