Accelerating gradient improvement from hole-boring to light-sail stage using shape-tailored laser front

Abstract

The accelerating gradient of a proton beam is a crucial factor for the stable radiation pressure acceleration, because quickly accelerating protons into the relativistic region may reduce the multidimensional instability grow to a certain extent. In this letter, a shape-tailored laser is designed to accelerate the protons in a controllable high accelerating gradient in theory. Finally, a proton beam in the gigaelectronvolt range with an energy spread of ∼2.4% is obtained in one-dimensional particle-in-cell simulations. With the future development of the high-intense laser, the ability to accelerate a high energy proton beam using a shape-tailored laser will be important for realistic proton applications, such as fast ignition for inertial confinement fusion, medical therapy, and proton imaging.

Direct Acceleration of an Annular Attosecond Electron Slice Driven by Near-Infrared Laguerre–Gaussian Laser

“…It should be noted that the longitudinal electric field (E x ) of the LG laser plays an important role in accelerating the electron slice to a high energy in the 'bubble' mechanism in this paper, where the charge-separation field between the electron and ion slice is not considered. It is reasonable because the normalized amplitude of the charge-separation field a cs = π n e l 0 ∼ 0.08 for the initial foil thickness l 0 = 0.05λ and density n e = 0.5n c [56][57][58][59] is much lower than the longitudinal amplitude a x = 1.03 (corresponding to 1.67 ×10 12 V/m) for the LG laser used in our case. In this way, the dynamics of the electrons only driven by the LG laser field can be considered in Equation (2).…”

“…The laser beam arrives at the front surface of the target at t = 11T. The electrons are quickly pushed away from the target area because the ponderomotive force is much greater than the charge-separated field force between the electrons and protons in this case [58][59][60][61]. The electrons are then continuously accelerated through the DLA mechanism, as shown in Fig.…”

“…Such high quality of the annular electron slice may have various applications, such as antiprotons in conventional linear accelerators[49] , edge-enhancement electron imaging[50] , structured X-ray generation[51] , and analysis and manipulation of nanomaterials[52] .It should be noted that the longitudinal electric field (E x ) of the LG laser plays an important role in accelerating the electron slice to a high energy in the 'bubble' mechanism in this paper, where the charge-separation field between the electron and ion slice is not considered. It is reasonable because the normalized amplitude of the charge-separation field a cs = π n e l 0 ∼ 0.08 for the initial foil thickness l 0 = 0.05λ and density n e = 0.5n c[56][57][58][59] is much lower than the longitudinal…”

Monoenergetic proton beam accelerated by single reflection mechanism only during hole-boring stage

“…It should be noted that the efficiency of proton acceleration only in the HB stage seems lower, compared to the previous PRA process including the LS stage [18, 20, 21, 32] . In previous works, the laser interacts with the proton beam for a longer time, so that a higher beam energy (GeV, even 10 GeV) and higher accelerating efficiency can be obtained.…”

“…Radiation pressure acceleration (RPA) [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] is usually considered as an efficient mechanism to accelerate the whole target to gigaelectronvolts through the 'holeboring' (HB) [16,31] and 'light-sail' (LS) [18,20,21,32] stages. However, the beam spectra in RPA experiments [22,26,29] are much worse than what the theoretical results indicate [16-21, 23-25, 27, 28] .…”