Figure 1

Schematic of positron acceleration in the wake driven by an electron or laser beam driver.Reuse & Permissions

Figure 2

Schematic positron generation and loading scheme. The two incoming electron bunches (1, 2) generate two positron bunches ($1^{\prime }$, $2^{\prime }$) in a thin foil target. Only the drive electron bunch (1) and positron beam load ($2^{\prime }$) remain in the plasma after a short distance.Reuse & Permissions

Figure 3

EGS5 simulation results after a 0.5 mm Tantalum target: energy spectra of (a) the electron bunch and of (b) the produced positron bunch. Insets are the angular distributions in the $y$ direction.Reuse & Permissions

Figure 4

3D OSIRIS simulation results of plasma wakefields for case 1 at a distance 9.5 cm into the plasma: (a) longitudinal wakefield (${\mathrm{E}}_z$) lineout along the $z$ axis, and (b) along $x$ at $z=107\mu \mathrm{m}$ where the positron beam load is located; (c) transverse wakefield (${\mathrm{E}}_x\mathrm{\text{−}}{\mathrm{B}}_y$) lineout in the $x\mathrm{\text{−}}z$ plane along $z$ at $x=4.6\mu \mathrm{m}$; and (d) along $x$ at $z=107\mu \mathrm{m}$. In (a), the leading electron and the trailing positron bunch current profiles along $z$ are indicated by the blue lines. The rectangle indicates the location where the wakefields are both accelerating and focusing for positrons and where the positron beam load is placed. In (c), the trailing positron bunch current profile along $x$ is indicated by the blue line. Those bunches propagate to the right.Reuse & Permissions

Figure 5

3D simulation results for case 1 after a propagation distance in the plasma of 0.02 cm (left-hand panels) and 9.5 cm (right-hand panels). $x\mathrm{\text{−}}z$ slices of the plasma density (a) and (a’), and electron beam density (b) and (b’) and positron beam density (c) and (c’). [Note that maximum density is $1\times {10}^{18}$ in (b) and $5\times {10}^{17}$ in (b’)].Reuse & Permissions

Figure 6

(a) Evolution of the energy at the peak of distribution of the positron beam load for case 1 (blue solid circle) and case 2 (red solid circle), and the corresponding relative energy spread (blue and red hollow diamonds, respectively). (b) Energy spectra of the positron beam load after $s=0.02\mathrm{cm}$ (red line) and $s=1\mathrm{m}$ of plasma (blue line) for case 1.Reuse & Permissions