MeV proton acceleration at kHz repetition rate from ultra-intense laser liquid interaction

Abstract

We regret overlooking two important citations relevant to the current work, and wish to add these [1, 2]. We also cite [3], which reports crucial experimental parameters pertaining to [1], e.g. chamber pressure during water target experiment. To correct the oversight of missing references, the 4th paragraph of the introduction follows with modified and additional text underlined:Liquid targets have a number of attractive features for meeting these needs. Liquid targets can be rapidly delivered into the interaction region, and mitigate debris [31,[34][35][36]. This is well illustrated by the pioneering research in [1, 3], who, for the first time combined a kHz, femtosecond laser and liquid jet targets with a long-term vision of developing integrated sources of energetic radiation and particles for future applications. They reported the production of 9.25 keV x-rays from the interaction of a kHz, 50 fs pulsed laser interacting with a liquid Ga jet target. They also reported the use of CR39 film to record the production of 500 keV protons from the interaction of the kHz laser with an intensity of 3×10 16 W cm −2 focused on a 10-30μm diameter water jet, with a background chamber pressure of 0.7-3 mbar. The proton production efficiency of 10 −5 % was reported. Prior to switching to the liquid sheet target described in our current work, we attempted to obtain protons from the interaction of 15-30μm diameter water jets with a 40 fs pulsed laser focused to an intensity of 1×10 18 W cm −2 . We recorded many tracks on the CR39 film but, when a magnetic spectrometer was used, all of the tracks were shown to be due to electrons. As noted in this paper, we later discovered that the chamber background pressure required to produce a significant flux of protons was below the freeze point pressure of water.Skip to the end of the last sentence of the paragraph and add as the last sentence of the paragraph: the ability to generate a well collimated proton beam with proton energies greater than 500 keV has recently been demonstrated [2], using a high repetition rate 0.5 kHz, 3 mJ, 55 fs laser interacting with a solid target. The focus intensity was 2×10 18 W cm −2 . A proton beam was generated at the front surface of a rotating optical quality glass disk at a chamber pressure of 3×10 −3 mbar. AbstractLaser acceleration of ions to MeV energies has been achieved on a variety of Petawatt laser systems, raising the prospect of ion beam applications using compact ultra-intense laser technology. However, translation from proof-of-concept laser experiment into real-world application requires MeV-scale ion energies and an appreciable repetition rate (>Hz). We demonstrate, for the first time, proton acceleration up to 2 MeV energies at a kHz repetition rate using a milli-joule-class short-pulse laser system. In these experiments, 5 mJ of ultrashort-pulse laser energy is delivered at an intensity neaŕ -5 10 W cm 18 2 onto a thin-sheet, liquid-density target. Key to this effort is a flowing liquid ethylene glycol target formed i...

Enhanced laser-driven hadron sources with nanostructured double-layer targets

“…Moreover, for selected applications, the inherently broad energy spectrum of a laser-driven ion source [2] is not detrimental [15,17] and could even be beneficial [18]. Maximum ion energies of ∼1 MeV have been recently demonstrated even with commercial, sub-terawatt laser systems [38]. These lasersystems are truly table-top and can operate at a high repetition rate (kiloHertz).…”

High-repetition-rate ( kHz) targets and optics from liquid microjets for high-intensity laser–plasma interactions

“…e amount of overlap between the two jets, ∆x, ultimately de nes the minimum thickness of the sheet. At normal incidence the thickest sheet is formed, is gure is reprinted with permissions from Morrison et al 2018 [81] . typically resulting in a minimum thickness of a few microns.…”

“…Lastly, the thickness stability of the sheet was found to be stable to be er than 3 nm over a 10 µm patch as evidenced by the etalon-like thin lm interference measurement performed in Section 5. e above described submicron thick, planar liquid sheet target has already been demonstrated for use in high intensity, high repetition rate LPI experiments. Morrison et al 2018 employed this target, in combination with a kHz repetition rate, millijoule-class, relativistically intense laser to generate energetic protons at up to 2 MeV at kHz repetition rate [81] . Previous e orts to accelerate ions at kHz repetition have relied on front surface TNSA from relatively thick targets, providing diminished e ciencies compared to rear surface TNSA [82] .…”

Paving the way for a revolution in high repetition rate laser-driven ion acceleration

“…The challenge in producing these sources lies not only in the development of stable, high energy, high repetition rate laser systems but also of suitable targetry and diagnostics. In the paper of Morrison et al (2018), the authors demonstrate a novel planar target compatible with kHz production of MeV proton beams and kHz-compatible beam diagnostics, which represent important steps in the development of laser-driven ion sources for applications.While energetic ions were measured during laser-plasma interactions in the mid-1980s, the development of chirped pulse amplification, allowing amplification of short laser pulses to higher energy, lead to a dramatic enhancement in acceleration to tens MeV energies. When the high intensity (I L >10 18 W cm −2 ) laser pulse is incident on a target, typically a few microns in thickness, a dense plasma is formed and the newly freed electrons are rapidly accelerated to relativistic energies in the laser fields.…”

“…The challenge in producing these sources lies not only in the development of stable, high energy, high repetition rate laser systems but also of suitable targetry and diagnostics. In the paper of Morrison et al (2018), the authors demonstrate a novel planar target compatible with kHz production of MeV proton beams and kHz-compatible beam diagnostics, which represent important steps in the development of laser-driven ion sources for applications.…”