近年来激光等离子体加速取得了重要突破，已经可以在厘米的尺度上获得GeV量级准单能电子束。通常离子比电子重几千倍，相比而言加速更为困难。光压加速在理论上可以有效加速离子，我们在前期研究中提出和验实了光压稳相加速机制的存在，加速得到了几十MeV的质子和准单能碳离子。由于存在不稳定性，在激光穿透薄靶之后，大部分激光能量不能继续用来加速离子，从而限制了激光的转化效率。在纳米靶之前增加临界密度等离子体，可以有效提高激光的吸收效率，近期我们也在实验上初步证实能够提高离子加速效率2~3倍以上。本项目拟在前期研究基础之上，着重研究临界密度等离子体靶和相应的复合结构靶（例如碳纳米管和尺度可控的预等离子体），进一步从理论和实验上探索新的加速机制和方法，在激光离子加速中取得重要突破，力争获得40~60MeV的质子，推动激光离子加速器走向应用。

In recent years, the laser plasma accelerator can generate mono-energetic GeV-level electron beam in cm scale, while it is hard to accelerate ion because the it is thousands time heavier than the electron. The radiation pressure acceleration (RPA) can efficiently accelerate the ions theoretically if hitting the foil by an ultraintense laser pulse, which was demonstrated experimentally. However, most of laser energy is wasted when laser breaks through the foil, because the transverse instabilities always destroy the foil quickly. In this project, we are aiming at the new acceleration mechanism based on the critical dense plasmas and related complex target, there will be new breaking results for application of laser plasma accelerator in the near future.