Laser acceleration physics and technology
1. Experimental research and application of laser ion acceleration
The laser acceleration mechanism breaks through the bottleneck of the material ionization breakdown threshold in traditional accelerators and greatly increases the acceleration gradient to MeV/μm. Laser-accelerated ion beam is characterized of extremely small source size, short duration, and large energy spectrum width. It can be applied to inertial confinement fusion fast ignition, ion probe for magnetic confinement fusion, ionography, proton ultrasound, ion implantation to traditional accelerators, and cancer radiotherapy, etc. So far, theories predict a variety of laser acceleration schemes for ion beams such as radiation pressure acceleration, electrostatic shockwave acceleration, high-efficiency cascade acceleration, etc. However, there are many problems remain to be solved urgently such as how to verify these scheme experimentally and use these schemes to produce high-energy and high-quality ion beams. At the same time, novel applications in chemistry, materials science, and biomedicine based on the unique physical properties of laser-driven ion beams are also very promising research directions.
2. Novel light source driven by ultra-intense laser
When the ultra-intense laser interacts with plasma, it can accelerate electrons to almost the speed of light at the femtosecond and micron-meters space-time scale, driving the collective motion of a large number of electrons. In this process, ultra-high-brightness radiation of a band from terahertz to gamma is generated. Compared with traditional large light sources, these novel light sources have the advantages of small source size, high transient brightness, compact equipment, and high flexibility. In recent years, research on this type of novel light source has become a hotspot in the fields of laser plasma physics and novel accelerators. Among them, the use of PW-level high-power lasers to generate high-brightness gamma radiation has recently achieved many important breakthroughs. Theoretical studies have shown that near-critical density plasma can convert laser energy into high-energy photon most efficiently. Research on novel light sources based on near-critical density plasma has a wide space.
3. Laser acceleration and laser nuclear physics research based on nano-targets
New target materials play an important role in enhancing laser acceleration and understanding the physical process of laser acceleration. Among them, the nano-target has a unique scale effect, which has a strong influence on the laser acceleration process. For example, nanowire targets can promote the coupling of laser and plasma, enhance ion acceleration, and produce high-temperature and high-density systems. In the extreme environment formed by the laser and the nano-target, the study of the nuclear reaction cross section in the plasma environment can be carried out. This will provide new research ideas for laser nuclear physics and nuclear astrophysics.
4. Key technologies of laser accelerators for medical application
The use of laser acceleration in the medical field, such as laser proton radiotherapy systems, is expected to reduce the cost and size of cancer treatment devices and benefit a wider range of patients. Difficulties to be overcome include the production of protons above 100 MeV, the development of a repetitive frequency continuous target shooting system, the high-quality and mass preparation of advanced nano-targets, and the comprehensive diagnosis of laser acceleration processes.