This work shows for the first time the laser plasma accelerator integrated with a magnet lattice can deliver reliably protons with ideal beam qualities, such as 1% energy spread of different energies and good uniformity. This experiment also demonstrates precise adjustment of the laser accelerated proton beam in terms of energy, charge and diameter with repeatability and availability.
Spread-Out Bragg Peak (SOBP) with three-dimensional radially symmetric dose distribution for cancer therapy, the key technology of proton radiotherapy for malignant tumors, is therefore realized with this laser accelerator for the first time. It raises the “laser acceleration” to “laser accelerator” of ~10 MeV protons through beam control since the invention of laser acceleration in 1979 by Tajima and Dawson.
Bending magnet properly integrated with triplet and doublet quadruple lenses can overcome inherent drawbacks of the laser driven beams. This technology demonstrated in the paper can be also applied to the high energy protons with energy over 250 MeV, resorting to pulsed magnets or superconducting magnets. With the development of high-rep rate PW laser technology, we can now envision a compact beam therapeutic machine of cancer treatment in the near future soon.
The research on ion acceleration driven by high intensity laser pulse has attracted significant interests in recent decades due to the developments of laser technology. The intensive study of energetic ion bunches is particularly stimulated by wide applications in nuclear fusion, medical treatment, warm dense matter production and high energy density physics. However, to implement such compact accelerators, challenges are still existing in terms of beam quality and stability, especially in applications that require higher energy and narrow bandwidth spectra ion beams.
We report on the acceleration of quasi-mono-energetic ion beams via ionization dynamics in the interaction of an intense laser pulse with a solid target. Using ionization dynamics model in 2D particle-in-cell (PIC) simulations, we found that high charge state contamination ions can only be ionized in the central spot area where the intensity of sheath field surpasses their ionization threshold. These ions automatically form a microstructure target with a width of few micron scale, which is conducive to generate mono-energetic beams. In the experiment of ultraintense (< 10^21 W/cm^2) laser pulses irradiating ultrathin targets each attracted with a contamination layer of nm-thickness, high quality < 100 MeV mono-energetic ion bunches are generated. The peak energy of the self-generated micro-structured target ions with respect to different contamination layer thickness is also examined
This is relatively newfound respect, which is confirmed by the consistence between experiment data and the simulation results.