Jianhui Bin

A laser-driven nanosecond proton source for radiobiological studies

Ion beams are relevant for radiobiological studies and for tumor therapy. In contrast to conventional accelerators, laser-driven ion acceleration offers a potentially more compact and cost-effective means of delivering ions for radiotherapy. Here, we show that by combining advanced acceleration using nanometer thin targets and beam transport, truly nanosecond quasi-monoenergetic proton bunches can be generated with a table-top laser system, delivering single shot doses up to 7 Gy to living cells. Although in their infancy, laser-ion accelerators allow studying fast radiobiological processes as demonstrated here by measurements of the relative biological effectiveness of nanosecond proton bunches in human tumor cells.

Enhanced Laser-Driven Ion Acceleration by Superponderomotive Electrons Generated from Near-Critical-Density Plasma

We report on the experimental studies of laser driven ion acceleration from a double-layer target where a near-critical density target with a few-micron thickness is coated in front of a nanometer-thin diamondlike carbon foil. A significant enhancement of proton maximum energies from 12 to ∼30  MeV is observed when a relativistic laser pulse impinges on the double-layer target under linear polarization. We attributed the enhanced acceleration to superponderomotive electrons that were simultaneously measured in the experiments with energies far beyond the free-electron ponderomotive limit. Our interpretation is supported by two-dimensional simulation results.

Integrated double-plasma-mirror targets for contrast enhancement in laser ion acceleration

We introduce a target concept for laser-driven ion acceleration with ultrashort, highly intense laser pulses that includes an integrated double plasma mirror for contrast enhancement. It comprises three nanometer thin plastic foils, embedded in a small metal structure, which ensures precise mounting. The geometry allows to apply a double plasma mirror directly in front of a target foil within the converging beam, enabling moderate-energy (~1 J) laser systems to reach the required fluence of several hundred J/cm2 on the plasma mirrors. During an experimental campaign, performed at the Laboratory for Extreme Photonics in Munich, we observed proton energies increased by a factor of three using this new target, which is attributed to an enhanced laser contrast after the integrated double plasma mirrors.

Considerations on employing a PMQ-doublet for narrow and broad proton energy distributions

Abstract We simulated a doublet of permanent magnet quadrupoles (PMQs) to estimate the sensitivity on positioning precision and its impact on the spectral properties of transported protons. The study guided the construction and testing of a focusing setup for laser-accelerated proton bunches with energies between 6 and 10 MeV. Our results shed light on possible applications that may arise from broad input particle spectra.

Generation of sub-cycle attosecond pulses from a single laser-driven relativistic electron sheet

Techniques that produce bright isolated attosecond pulses are very attractive for attosecond science. Here we report recent experimental results on generation of sub-cycle attosecond pulses from a signle laser-driven relativistic electron sheet.