High energy implementation of coil-target scheme for guided re-acceleration of laser-driven protons

Hamad Ahmed,Simon Ferguson,Mirela Cerchez,Thomas Hodge,Deepak Kumar,Andrea Macchi,Rajendra Prasad,Kealan Naughton,Deborah Gwynne,Marco Borghesi,Stephanie Brauckmann,Prokopis Hadjisolomou,Aaron Alejo,Satyabrata Kar,Giada Cantono,Oswald Willi,Domenico Doria,James Green

doi:10.1038/s41598-020-77997-w

Abstract

Developing compact ion accelerators using intense lasers is a very active area of research, motivated by a strong applicative potential in science, industry and healthcare. However, proposed applications in medical therapy, as well as in nuclear and particle physics demand a strict control of ion energy, as well as of the angular and spectral distribution of ion beam, beyond the intrinsic limitations of the several acceleration mechanisms explored so far. Here we report on the production of highly collimated (sim 0.2^{circ } half angle divergence), high-charge (10s of pC) and quasi-monoenergetic proton beams up to sim 50 MeV, using a recently developed method based on helical coil targetry. In this concept, ions accelerated from a laser-irradiated foil are post-accelerated and conditioned in a helical structure positioned at the rear of the foil. The pencil beam of protons was produced by guided post-acceleration at a rate of sim 2 GeV/m, without sacrificing the excellent beam emittance of the laser-driven proton beams. 3D particle tracing simulations indicate the possibility of sustaining high acceleration gradients over extended helical coil lengths, thus maximising the gain from such miniature accelerating modules.

Highlights

Developing compact ion accelerators using intense lasers is a very active area of research, motivated by a strong applicative potential in science, industry and healthcare
Application in cancer therapy would require the delivery of high energy protons (60–250 MeV)[2,3,4] with narrow energy spread and sufficient particle flux at significant distances from the interaction targets, so that the extraneous radiation produced during the intense laser interaction can be shielded adequately
The recently developed scheme based on helical coil (HC) targets[14] offers, in this context, a miniature and versatile setup that, in addition to reducing the divergence and energy spread of the beams, has been shown to post-accelerate the guided protons at a rate of the order of GV/m

Summary

Introduction

Developing compact ion accelerators using intense lasers is a very active area of research, motivated by a strong applicative potential in science, industry and healthcare. We report on the production of highly collimated (∼ 0.2◦ half angle divergence), high-charge (10s of pC) and quasi-monoenergetic proton beams up to ∼ 50 MeV, using a recently developed method based on helical coil targetry In this concept, ions accelerated from a laser-irradiated foil are post-accelerated and conditioned in a helical structure positioned at the rear of the foil. The recently developed scheme based on helical coil (HC) targets[14] offers, in this context, a miniature and versatile setup that, in addition to reducing the divergence and energy spread of the beams, has been shown to post-accelerate the guided protons at a rate of the order of GV/m In this scheme, the electromagnetic (EM) pulse generated due to transient charging of an intense-laser irradiated foil[14,15,16,17,18] is directed to travel. A current limitation of the scheme will be discussed, together with a possible scheme to overcome it towards the production of beamlets at energies of therapeutic interest

Methods

Results

Conclusion