We present time-dependent two-dimensional(2D) and three-dimensional(3D) fluid simulations of a gas cell with a variable length of 0-5 cm,designed for laser wakefield acceleration.The cell employs an output nozzle prod...We present time-dependent two-dimensional(2D) and three-dimensional(3D) fluid simulations of a gas cell with a variable length of 0-5 cm,designed for laser wakefield acceleration.The cell employs an output nozzle producing extended density ramps,which can facilitate the production of high-quality electron beams.In both geometries,the simulations demonstrate uniform density inside the cell.In the 3D case,the mean density inside the cell reaches a density nonuniformity below 1% after 100 ms.The density equilibrium time,τ,scales with the ratio of cell volume-tooutlet area,a relationship that is not captured by the 2D simulations showing five times shorter equilibrium time.We present a method to determine τ from fluid simulations,allowing the estimation of the minimum delay required to enable a uniform target density.Such uniformity prevents uncontrolled electron injection from density ripples,which has direct implications for optimizing beam quality and reproducibility in wakefield acceleration.展开更多
基金funding from STFC(ST/J002062/1,ST/P002021/1,ST/V001639/1)support from the Imperial College Research Computing Service
文摘We present time-dependent two-dimensional(2D) and three-dimensional(3D) fluid simulations of a gas cell with a variable length of 0-5 cm,designed for laser wakefield acceleration.The cell employs an output nozzle producing extended density ramps,which can facilitate the production of high-quality electron beams.In both geometries,the simulations demonstrate uniform density inside the cell.In the 3D case,the mean density inside the cell reaches a density nonuniformity below 1% after 100 ms.The density equilibrium time,τ,scales with the ratio of cell volume-tooutlet area,a relationship that is not captured by the 2D simulations showing five times shorter equilibrium time.We present a method to determine τ from fluid simulations,allowing the estimation of the minimum delay required to enable a uniform target density.Such uniformity prevents uncontrolled electron injection from density ripples,which has direct implications for optimizing beam quality and reproducibility in wakefield acceleration.
