摘要: Raising the repetition rate of ultrafast laser pulses that drive the laser wakefield acceleration (LWFA) can straightforwardly increase the average current of accelerated electrons and subsequently generate a high radiation flux desired in advanced X-ray radiography. Instead of using multi-TW laser pulses, the bottleneck of current ultrafast laser technology capable of producing pulses with an energy < 200 mJ at kHz-level frequencies motivates the development of LWFA methods that can be conducted with a moderate laser peak power approaching 1 TW. With the use of thin, high-density gas targets, principles of realizing the LWFA driven by pulses with a few-TW or even a sub-TW peak power will be introduced, including a comprehensive review to the recent simulations and experimental results in this field. Progress about the development of a diode-pumped, ytterbium-based ultrafast laser system expected to drive the sub-TW LWFA will be reported next. Moreover, results of LWFA experiments, when 800-nm pulses of a few-TW peak power are directed into sub-mm nitrogen gas jets and gas cells will be presented. This scheme exhibits a high potential for generating electrons with tens of MeV energies under a satisfactory reproducibility, which is the prerequisite for developing LWFA into a useful source in future radiation applications.