Abstract
Acceleration of dense matter to high velocities is of high importance for high energy density physics, inertial confinement fusion, or space research. The acceleration schemes employed so far are capable of accelerating dense microprojectiles to velocities approaching 1000 km/s; however, the energetic efficiency of acceleration is low. Here, we propose and demonstrate a highly efficient scheme of acceleration of dense matter in which a projectile placed in a cavity is irradiated by a laser beam introduced into the cavity through a hole and then accelerated in a guiding channel by the pressure of a hot plasma produced in the cavity by the laser beam or by the photonpressure of the ultraintense laser radiation trapped in the cavity. We show that the acceleration efficiency in this scheme can be much higher than that achieved so far and that subrelativisitic projectile velocities are feasible in the radiation pressure regime.
We acknowledge the expert support of M. Pfeifer, P. Pisarczyk, J. Skala, and the PALS laser team as well as useful discussion with J. Wołowski and YongJoo Rhee. This work was supported in part by the Ministry of Science and Higher Education (MNiSZW), Poland under Grant No N202 207438, the Czech Ministry of Education, projects MSM6840770022, MSM6840770010, LC528, and the Czech Science Fundation, Grant No. P201/10/P086. The experiment was performed within the Access to Research Infrastructure activity in the Seventh Framework Programme of the EU (Contract No 212025, Laserlab EuropeContinuation).
I. INTRODUCTION
II. LASERINDUCED CAVITYPRESSUREACCELERATION
III. THE HYDRODYNAMIC LICPA ACCELERATOR
IV. THE PHOTON PRESSUREDRIVEN LICPA ACCELERATOR
V. CONCLUSIONS
Key Topics
 Laser resonators
 24.0
 Kinematics
 16.0
 Hydrodynamics
 15.0
 Bubble dynamics
 13.0
 Laser beams
 13.0
F03H3/00
Figures
Two geometries of laserdriven accelerators of dense matter using LICPA: (a) the cylindrical accelerator and (b) the conical accelerator.
Two geometries of laserdriven accelerators of dense matter using LICPA: (a) the cylindrical accelerator and (b) the conical accelerator.
Replicas of craters produced in the massive Al targets by plasma projectiles accelerated in the LICPA and AA schemes with cylindrical and conical geometry. For the cylindrical geometry, the target was l_{t} = 20 μm CH foil, and L_{Ch} = 2 mm, d_{c} = 0.3 mm, L_{c} = 0.1 mm, d_{h} = 0.15 mm. For the conical geometry, the target was l_{t} = 25 μm CD_{2} foil, with r_{t} = 2 mm, L_{Ch} = 2 mm, L_{c} = 0.4 mm, d_{1} = d_{c} = 0.45 mm, d_{2} = 0.15 mm, d_{h} = 0.23 mm. All the accelerators were made of Au.
Replicas of craters produced in the massive Al targets by plasma projectiles accelerated in the LICPA and AA schemes with cylindrical and conical geometry. For the cylindrical geometry, the target was l_{t} = 20 μm CH foil, and L_{Ch} = 2 mm, d_{c} = 0.3 mm, L_{c} = 0.1 mm, d_{h} = 0.15 mm. For the conical geometry, the target was l_{t} = 25 μm CD_{2} foil, with r_{t} = 2 mm, L_{Ch} = 2 mm, L_{c} = 0.4 mm, d_{1} = d_{c} = 0.45 mm, d_{2} = 0.15 mm, d_{h} = 0.23 mm. All the accelerators were made of Au.
The volume of craters produced by the plasma projectile in the massive Al target, as a function of laser energy, for the cylindrical LICPA and AA schemes, with the same parameters as in Fig. 2. Circles, squares, and diamonds with error bars represent experimental data, while smaller bullets connected by solid lines represent numerical hydrodynamic simulations. Note that the crater volumes for AA are magnified by the factor 10 in the figure.
The volume of craters produced by the plasma projectile in the massive Al target, as a function of laser energy, for the cylindrical LICPA and AA schemes, with the same parameters as in Fig. 2. Circles, squares, and diamonds with error bars represent experimental data, while smaller bullets connected by solid lines represent numerical hydrodynamic simulations. Note that the crater volumes for AA are magnified by the factor 10 in the figure.
The volume of craters produced by the plasma projectile in the massive Al target, as a function of laser energy, for the conical LICPA and AA schemes with the same parameters as in Fig. 2. Note that the crater volumes for AA are magnified by the factor 10 in the figure.
The volume of craters produced by the plasma projectile in the massive Al target, as a function of laser energy, for the conical LICPA and AA schemes with the same parameters as in Fig. 2. Note that the crater volumes for AA are magnified by the factor 10 in the figure.
Temperature distributions of the Al target in the final stage of crater formation by the impact of the plasma projectile accelerated in the LICPA or in the AA cylindrical schemes with the same parameters as in Fig. 2. The gray boundary between the blue and the darkblue region is the boundary between the melted and the solid part of the target.
Temperature distributions of the Al target in the final stage of crater formation by the impact of the plasma projectile accelerated in the LICPA or in the AA cylindrical schemes with the same parameters as in Fig. 2. The gray boundary between the blue and the darkblue region is the boundary between the melted and the solid part of the target.
The electron isodensitograms and the space profiles of electron distributions for the plasma flowing out of the channel in the LICPA and AA cylindrical schemes recorded 23 ns after the target irradiation. CD_{2} target of l_{t} = 25 μm, L_{Ch} = 2 mm, d_{c} = 0.3 mm, L_{c} = 0.2 mm, d_{h} = 0.15 mm. 3ω laser beam of E_{L} = 177 J for LICPA and 180 J for AA. Note that the plasma driven by LICPA is faster and carriers much more electrons and ions than that driven by AA.
The electron isodensitograms and the space profiles of electron distributions for the plasma flowing out of the channel in the LICPA and AA cylindrical schemes recorded 23 ns after the target irradiation. CD_{2} target of l_{t} = 25 μm, L_{Ch} = 2 mm, d_{c} = 0.3 mm, L_{c} = 0.2 mm, d_{h} = 0.15 mm. 3ω laser beam of E_{L} = 177 J for LICPA and 180 J for AA. Note that the plasma driven by LICPA is faster and carriers much more electrons and ions than that driven by AA.
Plasma outflow velocity as a function of time for the plasma flowing out of the channel in the LICPA and AA cylindrical schemes with the same parameters as in Fig. 6. Note that the outflow velocity for AA scheme is magnified by the factor 10 in the figure.
Plasma outflow velocity as a function of time for the plasma flowing out of the channel in the LICPA and AA cylindrical schemes with the same parameters as in Fig. 6. Note that the outflow velocity for AA scheme is magnified by the factor 10 in the figure.
The ion current density of plasma driven by the 3ω laser beam in the LICPA and AA cylindrical schemes (of parameters as in Fig. 6) as well as of the plasma produced at the direct interaction of the beam with 25μm CD_{2} planar target. Note that the ion current densities for the AA scheme and the planar foil (the LT scheme) are magnified by the factor 5 in the figure. The ion current density is by more than a factor 10 higher and the mean ion energy is by more than a factor 4 higher for LICPA than those for AA and LT.
The ion current density of plasma driven by the 3ω laser beam in the LICPA and AA cylindrical schemes (of parameters as in Fig. 6) as well as of the plasma produced at the direct interaction of the beam with 25μm CD_{2} planar target. Note that the ion current densities for the AA scheme and the planar foil (the LT scheme) are magnified by the factor 5 in the figure. The ion current density is by more than a factor 10 higher and the mean ion energy is by more than a factor 4 higher for LICPA than those for AA and LT.
The acceleration efficiency of plasma projectiles driven in the LICPA and AA cylindrical schemes (with parameters as in Fig. 3), as a function of laser energy. Note that the acceleration efficiency for the AA scheme is magnified by the factor 5 in the figure.
The acceleration efficiency of plasma projectiles driven in the LICPA and AA cylindrical schemes (with parameters as in Fig. 3), as a function of laser energy. Note that the acceleration efficiency for the AA scheme is magnified by the factor 5 in the figure.
Snapshots of the space distributions of the ion charge ρ_{i} and the electron charge ρ_{e} for the carbon plasma projectile accelerated in the photon pressuredriven LICPA accelerator of L_{c} = 120 μm and R_{c} = 0.64. I_{L} = 2.5 × 10^{21} W/cm^{2}, τ_{L} = 2 ps, λ = 1.06 μm, L_{T} = 2 μm, n_{e} = 6n_{i} = 6 × 10^{23} cm^{−3}.
Snapshots of the space distributions of the ion charge ρ_{i} and the electron charge ρ_{e} for the carbon plasma projectile accelerated in the photon pressuredriven LICPA accelerator of L_{c} = 120 μm and R_{c} = 0.64. I_{L} = 2.5 × 10^{21} W/cm^{2}, τ_{L} = 2 ps, λ = 1.06 μm, L_{T} = 2 μm, n_{e} = 6n_{i} = 6 × 10^{23} cm^{−3}.
The ion energy spectra of plasma projectiles of various kinds of ions accelerated in the photon pressuredriven LICPA accelerator. For all kinds of ions, σ_{h} = ρL_{T} = 4 × 10^{−4} g/cm^{2} and L_{T}(Al^{+13}) = 1.48 μm, L_{T}(C^{6+}) = 2 μm, L_{T}(B^{4+}) = 2.16 μm, L_{T}(H^{+}) = 28.6 μm. Parameters of the LICPA accelerator and the laser driver are the same as in Fig. 10.
The ion energy spectra of plasma projectiles of various kinds of ions accelerated in the photon pressuredriven LICPA accelerator. For all kinds of ions, σ_{h} = ρL_{T} = 4 × 10^{−4} g/cm^{2} and L_{T}(Al^{+13}) = 1.48 μm, L_{T}(C^{6+}) = 2 μm, L_{T}(B^{4+}) = 2.16 μm, L_{T}(H^{+}) = 28.6 μm. Parameters of the LICPA accelerator and the laser driver are the same as in Fig. 10.
The acceleration efficiency and the mean ion energy per amu of plasma projectiles of various kinds of ions driven in the LICPA accelerator or in the conventional RPA scheme (no cavity) as predicted by PIC simulations and the generalized LS model. Parameters of the LICPA accelerator, the laser driver, and the target are the same as in Figs. 10 and 11. The acceleration length is l_{acc} = 200 μm.
The acceleration efficiency and the mean ion energy per amu of plasma projectiles of various kinds of ions driven in the LICPA accelerator or in the conventional RPA scheme (no cavity) as predicted by PIC simulations and the generalized LS model. Parameters of the LICPA accelerator, the laser driver, and the target are the same as in Figs. 10 and 11. The acceleration length is l_{acc} = 200 μm.
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