We report on the generation and laser acceleration of bunches of energetic deuterons with a small energy spread at about 2 MeV. This quasimonoenergetic peak within the ion energy spectrum was observed when heavy-water microdroplets were irradiated with ultrashort laser pulses of about 40 fs duration and high (10(-8)) temporal contrast, at an intensity of 10(19) W/cm(2). The results can be explained by a simple physical model related to spatial separation of two ion species within a finite-volume target. The production of quasimonoenergetic ions is a long-standing goal in laser-particle acceleration; it could have diverse applications such as in medicine or in the development of future compact ion accelerators.

We have analyzed the coupling of ultraintense lasers (at ∼2×10{19}  W/cm{2}) with solid foils of limited transverse extent (∼10  s of μm) by monitoring the electrons and ions emitted from the target. We observe that reducing the target surface area allows electrons at the target surface to be reflected from the target edges during or shortly after the laser pulse. This transverse refluxing can maintain a hotter, denser and more homogeneous electron sheath around the target for a longer time. Consequently, when transverse refluxing takes places within the acceleration time of associated ions, we observe increased maximum proton energies (up to threefold), increased laser-to-ion conversion efficiency (up to a factor 30), and reduced divergence which bodes well for a number of applications.

We experimentally demonstrate a notably enhanced acceleration of protons to high energy by relatively modest ultrashort laser pulses and structured dynamical plasma targets. Realized by special deposition of snow targets on sapphire substrates and using carefully planned prepulses, high proton yields emitted in a narrow solid angle with energy above 21 MeV were detected from a 5 TW laser. Our simulations predict that using the proposed scheme protons can be accelerated to energies above 150 MeV by 100 TW laser systems.

It's shown that the imposition of sub-laser wavelength relief structures on the surface of mass-limited-targets results into several folds higher short-pulse laser absorption, and consequently the efficient generation of fast ions. The optimum relief parameters for enhanced short-pulse laser absorption and higher ion acceleration are estimated numerically by particle-in-cell simulations and then corroborated by analytical scalings. The stability of the pre-imposed surface modulation during the laser pulse foil interaction is also examined.

An unprecedented increase of kinetic energy of laser accelerated heavy ions is demonstrated. Ultra thin gold foils have been irradiated by an ultra short laser pulse at an intensity of 6 × 10 19 W/cm 2 . Highly charged gold ions with kinetic energies up to > 200 MeV and a bandwidth limited energy distribution have been reached by using 1.3 Joule laser energy on target. 1D and 2D Particle in Cell simulations show how a spatial dependence on the ions ionization leads to an enhancement of the accelerating electrical field. Our theoretical model considers a varying charge density along the target normal and is capable of explaining the energy boost of highly charged ions, leading to a higher efficiency in laser acceleration of heavy ions. PACS numbers:Laser driven ion acceleration has gained a wide scientific interest, as it is a promising ion source for investigation in basic plasma physics and for application in accelerator technology [1,2] related to bio-medical [3,4] and hadron research [5]. While the acceleration of protons and light ions are intensively investigated during the last decade, little is reported on acceleration of heavier ions [6]. Such knowledge is mandatory to achieve the objectives of upcoming new laser facilities [7,8], e.g. the exploration of nuclear, astrophysical questions as well as the potential use as beam lines for heavy ion radio therapy [9].Energies of heavy ions exceeding the mass number A 12 with E kin /u ∼ 1−2 MeV/u (energy per nucleon) have been reported so far [6,10], by using short pulse laser systems with laser pulse energies well above 20 J [11].In the following we report and discuss a considerable energy boost for acceleration of the highly charged heavy ions with only using 1.3 J on an ultra thin heavy material target. We accelerated ions up to E M ax /u > 1 MeV/u, with a bandwidth limited energy distribution. We found a remarkable deviation in the maximum energy to charge Z scaling in comparison to established models of Mora [12] and Schreiber [13,14].Presently used laser ion acceleration schemes like Target Normal Sheath Acceleration (TNSA) [15], or leaky light sail / Radiation Pressure Acceleration (RPA) [16][17][18], Coherent Acceleration of Ions by Laser (CAIL) [4,19], Break Out Afterburner (BOA) [20] make use of an energy transfer from laser to electrons and in a following step electrons accelerate the ions. In the typical physical picture, an ultra intense laser is focused on a thin target, ionizes it and displaces the electrons from the ion background by the laser field. This creates a high electrical field at the rear and front side of the target. The Coulomb attraction field of the ions circumvents the electrons escape and enables the acceleration of the ions. For ultra thin targets and relativistic laser intensities, the acceleration is enhanced by the transparency of the target and the relativistic kinematics of the electrons [18,[21][22][23]. Further optimization for the energies of light ions is proposed by a Coulomb exploding background of heavy ion constituen...