An automated, 0.5 Hz nano-foil target positioning system for intense laser plasma experiments

Abstract

We report on a target system supporting automated positioning of nano-targets with a precision resolution of 4 µm in three dimensions. It relies on a confocal distance sensor and a microscope. The system has been commissioned to position nanometer targets with 1 Hz repetition rate. Integrating our prototype into the table-top ATLAS 300 TW-laser system at the Laboratory for Extreme Photonics in Garching, we demonstrate the operation of a 0.5 Hz laser-driven proton source with a shot-to-shot variation of the maximum energy about 27% for a level of confidence of 0.95. The reason of laser shooting experiments operated at 0.5 Hz rather than 1 Hz is because the synchronization between the nano-foil target positioning system and the laser trigger needs to improve.

Relativistically Intense Laser–Microplasma Interactions

“…Besides trapped particles (cf. chapter 5), suitable target concepts could be cryogenic jets [186], droplets [9], or even modified versions of target wheels [272] and tape-drive targets [273]. Promising detectors for such application need faster evaluation than those used here.…”

“…Targets are commercially available in large quantities, and come in monodisperse, chemically grown and well characterized samples. This reduces both cost and effort for on-site target-characterization (usually required for modern foil-targets [272]) to essentially zero. A single target can be as cheap as 10 −10 USD.…”

Review of HPLSE special issue on target fabrication

“…An investigation progress toward Be-based ablator materials for the inertial confinement fusion [4] 7. Review on high repetition rate and mass production of the cryogenic targets for laser IFE [5] 8. An automated, 0.5 Hz nano-foil target positioning system for intense laser plasma experiments [11] 9. Laser-induced microstructures on silicon for laserdriven acceleration experiments [14] 10.…”

“…Submissions for the special issue covered the invited topics and also branched out into broader areas and capabilities. Papers described research on: techniques for the production of targets for inertial confinement fusion (ICF) [1][2][3][4][5][6][7][8] , micro-assembly [3,8,9] , liquid targets [10] , systems for delivery of targets at high repetition rates [5,11,12] , fundamental target fabrication processes [2,4,[13][14][15][16] , low density materials [15,17,18] and metrology methods [7,18,19] . In addition, there were three important review papers [1,5,12] that give an excellent snapshot of the current capabilities across the world.…”

Real-time target alignment system for high-power high-repetition rate laser operations using a five degree-of-freedom hybrid mechanism

“…For example, clinically relevant experiments require several thousands of laser shots, which demand for an automated target positioning system. One method of automated positioning of nano-scale targets was reported by Gao et al (2017). With the use of a six-axis hexapod, a specially designed target wheel, a microscope and a confocal chromatic displacement sensor, they achieved a target positioning accuracy of around 5 μm in all spatial dimensions at 0.5 Hz repetition rate; but this method represents a pre-calibrated compensation for target's positional deviations.…”