Search NASA⌕ Search

SEARCH · Search NASA

Results for “laser generated ion beams”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Ion beams from laser-generated plasmas

The paper describes the space-charge-limited beams produced by the plasma blowoffs generated by 20-MW bursts of 1.06-micron radiation from an active Q-switched Nd:YAG laser. Laser power densities near 10 to the 11th/sq cm on solid targets generate thermalized plasma plumes which drift to a 15-kV gridded extraction gap where the ions are extracted, accelerated, and electrostatically focused; the spatially defined ion beams are then magnetically analyzed to determine the charge state content in the beams formed from carbon, aluminum, copper, and lead targets. This technique preserves time-of-flight (TOF) information in the plasma drift region, which permits plasma ion temperatures and mass flow velocities to be determined from the Maxwellian ion curve TOF shapes for the individual charge species.

Hughes, R. H.↗
DOE OSTI2021

Study of Ion Generation by a ps-laser for External Injection into Electron Beam Ion Source

We investigated ion generation from Al, Ti, Cu, Nb and Ta target elements by a picosecond-laser in the range of 10 11 – 10 13 W/cm 2 power densities at the target surface. A ps-laser with 1.27 mJ maximum energy within a 8 ps pulse and repetition rate up to 400 Hz has been used to generate a laser-ablated plasma. Dependencies of ion current vs time, total charge of registered ions as well as ion kinetic energy distributions are characterized using a Faraday cup. Significant difference in ion current dynamics between first, second and following shots onto the same target spot was found for all five target elements. The total charge of ions registered by the Faraday cup increase linearly with increasing laser pulse energy and are almost independent on the target element and number of shots onto the same target spot for all five target elements studied. Target craters have been examined using a commercially available microscope (Nikon Eclipse LV150) and crater cross section areas were found to be in the range of 0.0076 – 0.0172 mm 2 within the first five shots onto the same target spot for different target elements. A linear dependence of crater cross section square on laser pulse energy has been observed for the Ta target. Ion energy distributions for all target elements have a plateau or a slight peak in the energy range of 10 - 100 eV and long low-intensity energy tail up to tens of keV.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

Super-strong magnetic field-dominated ion beam dynamics in focusing plasma devices

High energy density physics is the field of physics dedicated to the study of matter and plasmas in extreme conditions of temperature, densities and pressures. It encompasses multiple disciplines such as material science, planetary science, laboratory and astrophysical plasma science. For the latter, high energy density states can be accompanied by extreme radiation environments and super-strong magnetic fields. The creation of high energy density states in the laboratory consists in concentrating/depositing large amounts of energy in a reduced mass, typically solid material sample or dense plasma, over a time shorter than the typical timescales of heat conduction and hydrodynamic expansion. Laser-generated, high current–density ion beams constitute an important tool for the creation of high energy density states in the laboratory. Focusing plasma devices, such as cone-targets are necessary in order to focus and direct these intense beams towards the heating sample or dense plasma, while protecting the proton generation foil from the harsh environments typical of an integrated high-power laser experiment. A full understanding of the ion beam dynamics in focusing devices is therefore necessary in order to properly design and interpret the numerous experiments in the field. In this work, we report a detailed investigation of large-scale, kilojoule-class laser-generated ion beam dynamics in focusing devices and we demonstrate that high-brilliance ion beams compress magnetic fields to amplitudes exceeding tens of kilo-Tesla, which in turn play a dominant role in the focusing process, resulting either in a worsening or enhancement of focusing capabilities depending on the target geometry.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

High-energy ion beams generated with high efficiency using laser-driven 3D microstructures

Laser-driven ion acceleration in plasma is being proposed as a source of ion beams with a high peak current that can be useful in many fields of science and medicine. Using this method, high proton energies have been achieved by increasing the laser power and by using ultrathin (≤ 200 nm) foils. However, this approach is limited by survivability of the nanotargets to laser prepulses and by difficulty in controlling the plasma acceleration properties. Here, we introduce a new target platform using two-photon polymerization, 3D laser-printed “clone” microstructures with average densities lower than solid that are relatively insensitive to the laser prepulse. Two types of microstructured targets consisting of either a multilayered log-pile or a stochastic arrangement of one micron diameter wires are used. Both demonstrate a higher energy and higher yield proton acceleration compared to thin solid-density foil targets by the robust target normal sheath acceleration (TNSA) mechanism. We find that when such 10–20 μm thick structures are irradiated with a petawatt laser, protons with energies up to 110 MeV and a laser-to-proton conversion efficiency of ~ 10% are obtained. Our work suggests that such microstructures optimized for 60–200 MeV compact proton accelerators are promising for future radiotherapy and other applications.

Physics - Plasma physics↗
DOE OSTI2020

Design of target irradiation and diagnostic chamber to study ps-laser generated plasma as a source of singly charged ions for external injection into an electron beam ion source

High repetition-rate (~10 kHz) ps-lasers are becoming available on the market with reasonable cost and may offer several advantages compared to ns-lasers by generating nearly continuous beams of singly charged ions appropriate for the “slow” injection mode into the Electron Beam Ion Source (EBIS). To evaluate these advantages, we will perform studies of a ps-laser generated plasma using a laser with a pulse duration of 8 ps and energy up to 5 mJ per pulse. A vacuum chamber equipped with a 3D target positioner, a focusing lens, and a Faraday Cup has been designed and built for this study. Lens-to-target distance variations have been measured using a laser tracker over the whole range of horizontal and vertical translation for all five targets we will use. The variations were found to be within ±150 µm. This level of “target flatness” should be acceptable for our experimental conditions. Ion currents and ion pulse durations of various elements (from Al to Ta) will be measured for different target irradiation conditions (focal spot size and laser pulse energy). The results obtained will allow us to specify all parameters and geometry of a laser ion source based on a ps-laser to provide external ion injection into the relativistic heavy ion collider EBIS

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

Fast ignition inertial fusion energy using laser-driven ion beams

Ion fast ignition (IFI), or fusion fast ignition initiated by a laser-driven ion beam, is a promising path to high-gain inertial fusion energy (IFE). In IFI, cold, dense deuterium-tritium (DT) fuel is first assembled using lasers or pulsed power drivers. Then, a high-power ion beam is focused onto a small volume within the fuel (the hot spot), heating the fuel rapidly to conditions where fusion ignition takes place. Fusion burn in this hot spot propagates to the fuel surrounding the hot spot, leading to burnup of a significant fraction of this fuel and the possibility of high gain (G~100), as needed for inertial fusion energy. IFI uses separate drivers for the two basic elements, fuel compression and ignition, allowing maximum control and optimization of each. On the other hand, conventional laser fusion uses multiple beams of the same driver to compress the fuel and shock-heat its very center to ignite a burn wave. Despite impressive progress in conventional laser fusion, the precise spatial symmetry, temporal pulse shaping and timing required for high gain and IFE remain a serious unmet challenge.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

The effects of laser pulse length and collisional ionization on the acceleration of titanium ions

Abstract The interaction of a relativistic laser pulse ( > 10 18 W cm −2 µ m 2 ) with foil targets can accelerate ions to energies of tens of MeV u −1 with optimized laser and target parameters. We report the results on simulations of the interaction of a 6.0 × 10 20 W cm −2 laser pulse incident on ultrathin (10–500 nm) titanium foils to investigate the roles of laser pulse duration and ionization mechanisms in the acceleration of titanium ions. While holding peak intensity constant, two laser pulse durations were investigated, 140 and 650 fs. The optimum thickness is dependent on pulse duration, as it requires the concurrence of target transparency with the incidence of the peak laser intensity. The collisional processes do not play a significant role in Ti ion beam generation from the 140 fs laser pulse duration at the optimum thickness (30 nm). However, for the 650 fs laser optimum, collisions improve the conversion efficiency of highly energetic ( > 10 MeV u −1 ), high charge titanium (Ti 21 − 22 + ) by a factor of 20, and the titanium ion cutoff energy by ∼15%. This improvement is due to the fact that collisional ionization increases the electron density of the plasma, which delays the time of relativistic transparency, causing collisions to decrease the optimum foil thickness from 150 to 100 nm. Additionally, collisional ionization increases the charge-to-mass ratio of the titanium, and injects more electrons into the accelerating sheath field. At the optimum thickness, target normal sheath acceleration is the dominant mechanism of acceleration, with additional contributions from radiation pressure and shock wave acceleration.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

On the role of self-generated magnetic fields in focused ion beams driven by intense picosecond laser pulses

We investigate the physics of ion beam focusing in the interaction of intense picosecond laser pulses with concave foils, using two-dimensional particle-in-cell simulations. Curved targets have been observed to deliver brighter multi-MeV ion beams than flat targets, and they could be used to ignite pre-compressed ICF fusion capsules in a scheme called ion fast ignition. Focusing is achieved by shaping the target and relying on an ion acceleration mechanism in which the ions are accelerated normal to the target surface; subsequently, the plasma expansion grows magnetic fields that advect with the plasma and deflect ions away from the target symmetry axis, causing the focal spot to shift downstream from its geometric location. The drop in both electric and magnetic field strengths in the expanding plasma makes the ion beam envelope asymmetric with respect to the focusing plane.

Focused ion beam↗
NASA NTRS1975

Ionizing mechanisms in a cesium plasma irradiated with a ruby laser

A cesium filled diode--laser plasmadynamic converter was built to investigate the feasibility of converting laser energy to electrical energy at large power levels. Experiments were performed with a pulsed ruby laser to determine the quantity of electrons and cesium ions generated per pulse of laser beam and to determine the output voltage. A current density as high as 200 amp/sq cm from a spot of approximately 1 sq mm area and an open circuit voltage as high as 1.5 volts were recorded. A qualitative theory was developed to explain these results. In the operation of the device, the laser beam evaporates some of the cesium and ionizes the cesium gas. A dense cesium plasma is formed to absorb further the laser energy. Results suggest that the simultaneous absorption of two ruby laser photons by the cesium atoms plays an important role in the initial ionization of cesium. Inverse bremsstrahlung absorption appears to be the dominant mechanism in subsequent processes. Recombinations of electrons and cesium ions appear to compete favorably with the simultaneous absorption of two photons.

Shimada, K.↗
DOE OSTI2020

Neutron generator based on intense lithium beam driver

We are proposing a compact neutron generator based on a Li beam driver. The proposed neutron generator comprises a laser ion source, a radio-frequency quadrupole linear accelerator (RFQ linac), a drift tube linac, and a target containing protons. In the generator, the lithium ion is used as a projectile instead of protons to utilize the kinematic focusing technique. The technique enables us to enhance the neutron flux without increasing the beam energy, which is important to develop a clean compact neutron generator. Moreover, the combination of a laser ion source and a RFQ linac with the direct plasma injection scheme will provide several tens of mA of a fully ionized lithium beam, which is much higher than that of conventional heavy ion sources comparable with proton drivers. Neutrons are generated by the nuclear reaction of the lithium ions and protons in the beam target. In this paper, we reported the current status of the development. For RFQ, we designed the RFQ rods to accelerate 40 mA of 7Li3+. We fabricated and installed the rods into a cavity, and, as a first test, accelerated 10 mA of C6+ successfully.

Ikeda, Shunsuke (ORCID:0000000339800577)↗
DOE OSTI2024

Multi-Probe 24A: Post shot Data and Analysis

The Multi-Probe 24A experiments took place on the Omega EP laser in November 2023. The experiments consisted of shots alternating between Omega EP’s two short-pulse laser beams to generate proton and deuteron ion beams from a range of film thicknesses, and x-ray sources from the established CPC+Ta wire targets. The backlighter was used for ion acceleration in the pitcher series, in which deuteron and proton beams characterized as a function of CD film thickness to develop a pitcher for a pitcher-catcher neutron radiographic source, while also characterizing electrons and x-rays emitted perpendicular to the target (i.e. Crosstalk for sidelighter-driven x-ray beams). The sidelighter was used for electron acceleration in the x-ray series, in which the electron acceleration and subsequent x-rays was characterized from the CPC+Ta wire targets and radiography was conducted with and without electro-magnetic electron defection. For the pitcher series, we found that at 500 J and 0.7 ps the 700-800 nm CD films yielded the greatest number and highest energy for both protons and deuterons. For the x-ray series, results demonstrated: a significant number of <100 keV x-rays are produced within the glue that fills the CPC cone, on-axis electron signal from the x-ray targets produce electrons resolvable up to ~10 MeV, and electron deflection (using MIFEDS) has a notable effect radiograph on noise reduction.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Versatile tape-drive target for high-repetition-rate laser-driven proton acceleration

We present the development and characterization of a high-stability, multi-material, multi-thickness tape-drive target for laser-driven acceleration at repetition rates of up to 100 Hz. The tape surface position was measured to be stable on the sub-micrometre scale, compatible with the high-numerical aperture focusing geometries required to achieve relativistic intensity interactions with the pulse energy available in current multi-Hz and near-future higher repetition-rate lasers ( > kHz). Long-term drift was characterized at 100 Hz demonstrating suitability for operation over extended periods. The target was continuously operated at up to 5 Hz in a recent experiment for 70,000 shots without intervention by the experimental team, with the exception of tape replacement, producing the largest data-set of relativistically intense laser–solid foil measurements to date. This tape drive provides robust targetry for the generation and study of high-repetition-rate ion beams using next-generation high-power laser systems, also enabling wider applications of laser-driven proton sources.

47 OTHER INSTRUMENTATION↗
NASA NTRS1976

Laser plasmadynamic energy conversion

The generation of electrons ions by interacting an intense laser beam with cesium vapor is considered. Theoretical calculation shows that the conversion efficiency is as high as 40 percent if the entire photon energy is utilized in ionizing the cesium vapor that is generated initially by the incoming laser beam. An output voltage is expected to be generated across two electrodes, one of which is the liquid cesium, by keeping the other electrode at a different work function. Evaluation of the laser plasmadynamic (LPD) converter was performed using pulsed ruby and Nd-glass lasers. Although the results obtained to date indicate an efficiency smaller than that of theoretical predictions, an unoptimized LPD converter did demonstrate the capability of converting laser energy at large power levels. The limitations in the performance may by due to converter geometry, the types of lasers used, and other limitations inherent to the cesium plasma.

Shimada, K.↗
DOE OSTI2025

Replenishing liquid sheet targets to enable high-intensity high-repetition-rate laser–plasma interactions for ion-beam technology

We report on the development of a robust microfluidic nozzle capable of generating replenishing liquid sheet targets with sub-micron thickness at up to kHz repetition rates, a λ/20 surface flatness over areas of at least 100 μm 2 , and in-vacuum dimensions of 6 × 1.5 mm 2 . The platform was evaluated for stability under hundreds of 4.3 J laser shots at 0.5 Hz and 6 × 10 20 W/cm 2 peak intensity, delivered in burst mode, totaling 2.9 kJ on the target. The key metrics of the platform, including sheet characteristics, nozzle aperture morphology, and proton spectra, showed no measurable degradation in the performance of the liquid sheet platform following this experiment. Beyond its application to ion beam technology, we outline a pathway to further develop the capabilities of the platform into a high-repetition-rate plasma mirror.

depth profiling techniques↗
DOE OSTI2024

Dephasing of ion beams as magnetic vortex acceleration regime transitions into a bubble-like field structure

The interaction of an ultra-intense laser pulse with a near critical density target results in the formation of a plasma channel, a strong azimuthal magnetic field and moving vortices. An application of this is the generation of energetic and collimated ion beams via magnetic vortex acceleration. The optimized regime of magnetic vortex acceleration is becoming experimentally accessible with new high intensity laser beamlines coming online and advances made in near critical density target fabrication. The robustness of the acceleration mechanism with realistic experimental conditions is examined with three-dimensional simulations. Of particular interest is the acceleration performance with different laser temporal contrast conditions, in some cases leading to pre-expanded target profiles prior to the arrival of the main pulse. Preplasma effects on the structure of the accelerating fields are explored, including a detailed analysis of the ion beam properties and the efficiency of the process. Improved scaling laws for the magnetic vortex acceleration mechanism, including the laser focal spot size effects, are presented.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Ion Generation Using Frozen Xenon Target for Laser Ion Source

A frozen laser target that is in the gaseous phase at room temperature is advantageous for a laser ion source because it can avoid the accumulation of damage from laser irradiation by regeneration of the target surface by additional gas freezing. In this study, the possibility of forming a xenon ion beam with a current sufficient for heavy-ion inertial fusion (HIF) was investigated. The relationship between the frozen target growth and resulting ion current was analyzed to determine the optimal condition of laser irradiation that ensures stable supply of ion beams for a long time. A frozen target of xenon was formed on a mount cooled to 20 K using a Gifford McMahon cryocooler, and plasma was generated using a Nd:YAG laser. Here, the results showed that it is possible to supply a sufficient ion current for application of singly charged ions as a driver for HIF. Additionally, it was indicated that the xenon responsible for forming the plasma existed only at a certain depth from the target surface. The results imply that it is possible to obtain a stable ion supply for a long time by irradiating the target with a laser after the frozen xenon grows to a sufficient thickness.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Picosecond laser generated plasma as a source of singly charged ions for external injection into an EBIS

The focus of this paper is on practical aspects of ion generation by picosecond lasers as a source of low charge state ions for external injection of ions into an electron beam ion source (EBIS). For a ps-laser, compared to a ns-laser currently used at Relativistic Heavy Ion Collier Electron Beam Ion Source (RHIC EBIS), the influence of heat conductivity in the solid target is almost negligible, which results in a lower target consumption rate and less vacuum pressure rise. By using a laser with high repetition rate, it is possible to produce quasi continuous 1+ ion beams for periods of tens of milliseconds, making it possible to take advantage of the ability of the EBIS to accumulate ions in the “slow” injection capture mode. Producing such an ion pulse train is now feasible since ps-lasers with pulse energy up to 10 mJ and rep-rate up to 10 kHz have recently become commercially available. The advantages of this lower current accumulation scheme include: (1) easier beam transport due to lower space charge of lower beam currents required compared to the present single pulse fast injection scheme, (2) better EBIS pulse to pulse ion output stability since pulse to pulse ion variations of the laser source are averaged over a long train of laser pulses, and (3) the possible addition of an isotope separator in which rare beams could be produced and selected at run time from less expensive (unenriched) targets. We studied the properties of plasmas generated by a ps-laser with 1.27 mJ energy within an 8 ps pulse and a repetition rate up to 400 Hz at Argonne National Laboratory to investigate feasibility and specify parameters for a laser ion source for RHIC EBIS using a “slow” injection mode. Al, Ti, Cu, Nb, and Ta targets were tested with various target translation speeds. Here, we demonstrated that a both “slow” and “fast” injection modes are accessible with a single ion source geometry and single injection line, providing the most attractive option for an ion source for external injection into RHIC EBIS trap based on a ps-laser.

43 PARTICLE ACCELERATORS↗