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| 20 | | Laser-driven ion sources offer potential advantages in a range of disciplines, including radiotherapy, but the beams created have a large divergence, creating significant challenges for conventional technologies that often rely on asymmetric focusing and require strong magnetic fields. The Laser-hybrid Accelerator for Radiobiological Applications (LhARA) proposes the use of a Gabor lens as a symmetric focusing system to capture the laser-driven beam. A Gabor lens uses the electrostatic field of a confined electron plasma to focus positively charged particles. The focusing strength is determined by the electron density and length. |
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| 22 | | This contribution reports results from a Gabor lens testbench at Swansea University. A Penning-Malmberg trap, comprising a radially confining solenoid and axially confining electrodes, is used to confine an electron plasma produced through seeding background CO2 gas ionisation with an electron gun. Experimental results have explored rotating-wall techniques, oscillating electric fields and the introduction of a dimple potential. The combination of the dimple potential and oscillating fields has improved plasma stability. Peak densities of approximately 8 × 10¹⁴ m⁻³ have been achieved, approaching the design target for the proposed LhARA lens (4 x 10^15 m-3). |
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| 24 | | Complementary three-dimensional particle-in-cell simulations using WarpX are being developed to support the interpretation and optimisation of experimental measurements. In parallel, preliminary particle-tracking studies indicate that the experimentally achieved plasma density could provide sufficient focusing for positrons, motivating further simulation and experimental validation. |
| 25 | | Together, these results represent progress towards a stable, sufficiently dense plasma, marking crucial steps in the development of a Gabor lens for the capture and transport of laser-driven ion beams. |
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