Demonstration of particle bending in a curved plasma channel at SPARC_LAB

The active bending plasma device compared with a conventional bending magnet.

In a recently published paper in Physical Review Letters, the SPARC_LAB group presented a novel method for deflecting and guiding relativistic electron beams along curved paths using magnetic fields generated within plasma-discharge capillaries.
This pioneering approach promises to significantly mitigate the chromatic dispersion effects commonly encountered with conventional bending magnets, marking a substantial leap forward in the field.

The experimental results demonstrate that the guiding of electron beams through plasma-discharge capillaries is notably less influenced by chromatic dispersion, a phenomenon where particles of different energies follow slightly different paths, compared to traditional bending magnets. Enhanced numerical simulations support these findings, indicating that by increasing the discharge currents, the technique can be rendered nearly dispersionless.

According to Riccardo Pompili, head of the SPARC_LAB accelerator activities and Principal Investigator of the experiment, “the results obtained at SPARC_LAB follow previous studies on (straight) active-plasma lenses and show that the same working principle can be applied to curved geometries with the goal to guide and bend relativistic particle beams by means of a plasma-based device. For this purpose, a high-current discharge flowing within a curved capillary simultaneously with the beam was used. Significant R&D was needed to develop the high-current discharge pulser that can reach 2.2 kA peak currents. The results show that the guiding was correctly obtained and, unlike conventional bending magnets, it can be made achromatic (i.e., not affected by the beam energy spread) by tuning the discharge current.”

The study highlights the potential for this innovative method to pave the way for next-generation tabletop particle accelerator facilities. If compared to state-of-the-art bending magnets technology, its practical implementation would be very affordable in terms of size and costs.

Active-bending plasma represents therefore an innovative solution to develop ultracompact beam lines for existing or next-generation accelerator facilities. This development marks a promising step towards more compact, versatile, and economically feasible particle acceleration technologies.

Further reading:

Pompili et al. Phys. Rev. Lett. 132, 215001