Supersonic Gas Jet Target Research Articles

Characteristic diagnosis of supersonic gas jet target for laser wakefield acceleration with high spatial-temporal resolution Nomarski interference system

Gas targets hold distinctive significance and advantages in the field of laser-matter interaction. As a major type of gas targets, supersonic gas target is one of the most commonly used targets for laser wakefield acceleration (LWFA). The temporal-spatial resolution study of it could provide valuable data references for the LWFA experiment. In this work, a Nomarski interference system with high spatial-temporal resolution was set up to diagnose the jet process of supersonic gas jet target. The formation process of supersonic gas jet under different jet durations, different injection positions and different gas back pressures was studied. It is beneficial to determine the more optimized time and position of laser injection into target when conducting LWFA experiments. Therefore, the quality of the obtained electron beam and radiation source can be effectively improved.

Low- Q2 elastic electron-proton scattering using a gas jet target

In this paper, we describe an experiment measuring low-$Q^2$ elastic electron-proton scattering using a newly developed cryogenic supersonic gas jet target in the A1 three-spectrometer facility at the Mainz Microtron. We measured the proton electric form factor within the four-momentum transfer range of $0.01\le Q^2 \le 0.045(\text{GeV/c})^2$. The experiment showed consistent results with the existing measurements. The data we collected demonstrated the feasibility of the gas jet target and the potential of future scattering experiments using high-resolution spectrometers with this gas jet target.

Operation and characterization of a windowless gas jet target in high-intensity electron beams

A cryogenic supersonic gas jet target was developed for the MAGIX experiment at the high-intensity electron accelerator MESA. It will be operated as an internal, windowless target in the energy-recovering recirculation arc of the accelerator with different target gases, e.g., hydrogen, deuterium, helium, oxygen, argon, or xenon. Detailed studies have been carried out at the existing A1 multi-spectrometer facility at the electron accelerator MAMI. This paper focuses on the developed handling procedures and diagnostic tools, and on the performance of the gas jet target under beam conditions. Considering the special features of this type of target, it proves to be well suited for a new generation of high-precision electron scattering experiments at high-intensity electron accelerators.

Application of Nomarski interference system in supersonic gas-jet target diagnosis

Supersonic gas-jet target performs an important role in laser wakefield acceleration, and its density diagnosis is a significant part of target characteristic study. In this paper, a Mach–Zehnder and Nomarski interference system is set up and used for gas-jet target density diagnosis. We have investigated and compared the performance of the Mach–Zehnder part and Nomarski part. The feasibility of the Nomarski interferometer with vertical fringes has been verified. Moreover, it shows better stability and has a more compact structure, beneficial for obtaining more accurate and effective target density characterization in laser wakefield acceleration.

X-ray phase contrast imaging of spherical capsules.

We demonstrate that a laser-based synchrotron X-ray source can be used to image and characterize in a single laser shot spherical capsules similar to ICF targets. Thus, we establish this source potential for real-time ultrafast imaging of the ICF laser driver interaction with the target. To produce the X-ray beam we used a 160 TW high power laser system with 3.2 J and 20 fs incident on a supersonic gas jet target at 2.5 Hz repetition rate. We produced 2.7 × 109 photons/0.1% BW/sr/shot at 10 keV with a critical energy Ec = 15.1 keV. In our experimental conditions the spatial resolution was 4.3 μm in the object plane. We show that it is feasible to image the capsule structure and experimentally retrieve the phase information.

Supersonic gas-jet characterization with interferometry and Thomson scattering on the OMEGA Laser System.

A supersonic gas-jet target platform has been activated on the OMEGA Laser System. An analytic model for gas dynamics in a supersonic nozzle was used to predict gas-plume parameters and to design nozzles for use in laser-plasma experiments. The gas-jet system was analyzed with a Mach-Zehnder interferometer to study neutral density and with Thomson scattering to study plasma parameters on the OMEGA Laser System. These initial measurements demonstrate the capabilities of the OMEGA gas jet as a platform for future laser-plasma interaction science.

Stable electron beams from laser wakefield acceleration with few-terawatt driver using a supersonic air jet

The generation of stable electron beams produced by the laser wakefield acceleration mechanism with a few-terawatt laser system (600 mJ, 50 fs) in a supersonic synthetic air jet is reported and the requirements necessary to build such a stable electron source are experimentally investigated in conditions near the bubble regime threshold. The resulting electron beams have stable energies of (17.4 ± 1.1) MeV and an energy spread of (13.5 ± 1.5) MeV (FWHM), which has been achieved by optimizing the properties of the supersonic gas jet target for the given laser system. Due to the availability of few-terawatt laser systems in many laboratories around the world these stable electron beams open possibilities for applications of this type of particle source.

Reprint of: Reaction measurements with the Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas jet target

Abstract Explosive stellar environments are sometimes driven by nuclear reactions on short-lived, radioactive nuclei. These reactions often drive the stellar explosion, alter the observable light curves produced, and dictate the final abundances of the isotopes created. Unfortunately, many reaction rates at stellar temperatures cannot be directly measured in the laboratory, due to the physical limitations of ultra-low cross sections and high background rates. An additional complication arises because many of the important reactions involve radioactive nuclei which have lifetimes too short to be made into a target. As such, direct reactions require very intense and pure beams of exotic nuclei. Indirect approaches with both stable and radioactive beams can, however, provide crucial information on the nuclei involved in these astrophysical reactions. A major development toward both direct and indirect studies of nuclear reactions rates is the commissioning of the Jet Experiments in Nuclear Structure and Astrophysics (JENSA) supersonic gas jet target. The JENSA system provides a pure, homogeneous, highly localized, dense, and robust gaseous target for radioactive ion beam studies. Charged-particle reactions measurements made with gas jet targets can be cleaner and display better resolution than with traditional targets. With the availability of pure and localized gas jet targets in combination with developments in exotic radioactive ion beams and next-generation detector systems, the range of reaction studies that are experimentally possible is vastly expanded. Various representative cases will be discussed.

Reaction measurements with the Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas jet target

Explosive stellar environments are sometimes driven by nuclear reactions on short-lived, radioactive nuclei. These reactions often drive the stellar explosion, alter the observable light curves produced, and dictate the final abundances of the isotopes created. Unfortunately, many reaction rates at stellar temperatures cannot be directly measured in the laboratory, due to the physical limitations of ultra-low cross sections and high background rates. An additional complication arises because many of the important reactions involve radioactive nuclei which have lifetimes too short to be made into a target. As such, direct reactions require very intense and pure beams of exotic nuclei. Indirect approaches with both stable and radioactive beams can, however, provide crucial information on the nuclei involved in these astrophysical reactions.A major development toward both direct and indirect studies of nuclear reactions rates is the commissioning of the Jet Experiments in Nuclear Structure and Astrophysics (JENSA) supersonic gas jet target. The JENSA system provides a pure, homogeneous, highly localized, dense, and robust gaseous target for radioactive ion beam studies. Charged-particle reactions measurements made with gas jet targets can be cleaner and display better resolution than with traditional targets. With the availability of pure and localized gas jet targets in combination with developments in exotic radioactive ion beams and next-generation detector systems, the range of reaction studies that are experimentally possible is vastly expanded. Various representative cases will be discussed.

New supersonic gas jet target for low energy nuclear reaction studies

New supersonic gas jet target for low energy nuclear reaction studies

The JENSA Gas-Jet Target for Radioactive Beam Experiments at ReA3 and FRIB

A high-density supersonic gas-jet target named JENSA (Jet Experiments in Nuclear Structure and Astrophysics) has been constructed and commissioned at Oak Ridge National Laboratory. The target creates a localized (∼ 4mm wide) thick (∼1019 atoms/cm2) concentration of gaseous atoms (H, He, N, etc...) that are suitable for use in high-resolution experiments with radioactive beams. The interaction point of the beam with the gas-jet target is surrounded by silicon strip detectors from the SuperORRUBA (Oak Ridge Rutgers University Barrel Array) to detect reaction products with good energy (∼30 keV) and angular resolution (∼1 degree). Initial experiments are discussed along with plans for future use at Michigan State University.

A pulsed supersonic gas jet target for precision spectroscopy at the HITRAP facility at GSI

A pulsed supersonic gas jet target for experiments at the HITRAP facility at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt has been designed and built as a multi-purpose installation for key experiments on fundamental atomic physics in strong fields. This setup is currently installed at the Institut für Kernphysik of Goethe-University, Frankfurt am Main (IKF), in order to explore its operation prior to its installation at the HITRAP facility. Design and performance of the target are described. The measured target densities of 5.9×1012atoms/cm3 for helium and 8.1×1012atoms/cm³ for argon at the stagnation pressure of 30bar match the required values. The target-beam diameter of 0.9mm and the pulsed operation mode (jet built-up-time ≤15ms) are well suited for the use at HITRAP.

The Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas jet target

New radioactive ion beam (RIB) facilities will push further away from stability and enable the next generation of nuclear physics experiments. Of great importance to the future of RIB physics are scattering, transfer, and capture reaction measurements of rare, exotic, and unstable nuclei on light targets such as hydrogen and helium. These measurements require targets that are dense, highly localized, and pure. Targets must also accommodate the use of large area silicon detector arrays, high-efficiency gamma arrays, and heavy ion detector systems to efficiently measure the reaction products. To address these issues, the Jet Experiments in Nuclear Structure and Astrophysics (JENSA) Collaboration has designed, built, and characterized a supersonic gas jet target, capable of providing gas areal densities on par with commonly used solid targets within a region of a few millimeters diameter. Densities of over 5×1018atoms/cm2 of helium have been achieved, making the JENSA gas jet target the most dense helium jet achieved so far.

Nuclear physics experiments with a windowless supersonic gas jet target

A new windowless gas target has been developed in Mexico. It is a supersonic gas jet flow produced inside a vacuum chamber which can be coupled to a regular beam line in an accelerator laboratory as a differential pumping system brings the pressure of the gas target system down to a microTorr, or better, at the connecting stage.In this work, we present the system as it was designed and constructed as well as the first results using air, Nitrogen and Argon.

Nonlinear and long-term beam dynamics in low energy storage rings

Electrostatic storage rings operate at very low energies in the keV range and have proven to be invaluable tools for atomic and molecular physics. Because of the mass independence of electric rigidity, these machines are able to store a wide range of different particles, from light ions to heavy singly charged biomolecules, opening up unique research opportunities. However, earlier measurements have shown strong limitations in maximum beam intensity, fast decay of the stored ion current, and reduced beam lifetime. The nature of these effects has not been fully understood and an improved understanding of the physical processes influencing beam motion and stability in such rings is needed. In this paper, a comprehensive study into nonlinear and long-term beam dynamics studies is presented on the examples of a number of existing and planned electrostatic storage rings using the BETACOOL, OPERA-3D, and MAD-X simulation software. A detailed investigation into ion kinetics, under consideration of effects from electron cooling and multiple scattering of the beam on a supersonic gas jet target, is carried out and yields a consistent explanation of the physical effects in a whole class of storage rings. The lifetime, equilibrium momentum spread, and equilibrium lateral spread during collisions with the target are estimated. In addition, the results from experiments at the Test Storage Ring, where a low-intensity beam of ${\mathrm{CF}}^{+}$ ions at $93\text{ }\text{ }\mathrm{keV}/\mathrm{u}$ has been shrunk to extremely small dimensions, are reproduced. Based on these simulations, the conditions for stable ring operation with an extremely low-emittance beam are presented. Finally, results from studies into the interaction of 3--30 keV ions with a gas jet target are summarized.

Recoil-ion momentum spectroscopy applied to study charge changing collisions

We describe a setup for performing recoil-ion momentum spectroscopy using a supersonic gas jet target (COLTRIMS) and a multi-hit detector that has been assembled in our laboratory. The apparatus will be used in the study of momentum distributions of recoil -ions and molecule dissociation fragments produced in collisions that involve charge-changing states in the projectile. We give a description of the different components of the system and the method we use to obtain the momentum distribution. To test the performance of the setup we performed measurements for the single capture collision of 3He 2+ projectiles incident on a He target. The resolution of our spectrometer allowed the identification of capture to ground and excited states. We present state-selective cross sections for capture in the projectile energy range from 40 to 300 keV.

Synchrotron x-ray radiation from laser wakefield accelerated electron beams in a plasma channel

Synchrotron x-ray radiation from laser wakefield accelerated electron beams was characterized at the HERCULES facility of the University of Michigan. A mono-energetic electron beam with energy up to 400 MeV was observed in the interaction of an ultra-short laser pulse with a super-sonic gas jet target. The experiments were performed at a peak intensity of 5×1019 W/cm2 by using an adaptive optic. The accelerated electron beam undergoes a so called "betatron" oscillation in an ion channel, where plasma electrons have been expelled by the laser ponderomotive force, and, therefore, emits synchrotron radiation. We observe broad synchrotron x-ray radiation extending up to 30 keV. We find that this radiation is emitted in a beam with a divergence angle as small as 12×4 mrad2 and can have a source size smaller than 3 microns and a peak brightness of 1022 photons/mm2/mrad2/second/0.1% bandwidth, which is comparable to currently existing 3rd generation conventional light sources. This opens up the possibility of using laser-produced "betatron" sources for many applications that currently require conventional synchrotron sources.

Radiative Electron Capture to Continuum (RECC) in 90AMeV U88+(1s22s2) + N2: the Short Wavelength Limit of Electron Nucleus Bremsstrahlung

We have investigated the relation of forward emission cusp electron spectra and bremsstrahlung for 90AMeV U88+ + N2at the internal supersonic gas jet target of the ESR storage ring of GSI. We find that x ray photons measured in coincidence with cusp electrons originate from the short wavelength limit of the electron nucleus bremsstrahlung.

Proton-He3elastic scattering at low energies

We present new accurate measurements of the differential cross section $\ensuremath{\sigma}(\ensuremath{\theta})$ and the proton analyzing power ${A}_{y}$ for proton-$^{3}\mathrm{He}$ elastic scattering at various energies. A supersonic gas-jet target has been employed to obtain these low-energy cross-section measurements. The $\ensuremath{\sigma}(\ensuremath{\theta})$ distributions have been measured at ${E}_{p}=0.99$, 1.59, 2.24, 3.11, and 4.02 MeV. Full angular distributions of ${A}_{y}$ have been measured at ${E}_{p}=1.60$, 2.25, 3.13, and 4.05 MeV. This set of high-precision data is compared to four-body variational calculations employing realistic nucleon-nucleon ($\mathit{NN}$) and three-nucleon ($3N$) interactions. For the unpolarized cross section, the agreement between the theoretical calculation and data is good when a $3N$ potential is used. The comparison between the calculated and measured proton analyzing powers reveals discrepancies of approximately 50% at the maximum of each distribution. This is analogous to the existing ``${A}_{y}$ puzzle'' known for the past 20 years in nucleon-deuteron elastic scattering.

Two-center interference in fast proton–H2-electron transfer and excitation processes

The subject of this thesis is experimental studies of electron-transfer processes in ion-atom collisions at velocities significantly higher than typical orbital velocities of electrons in bound states of atoms or molecules. The experimental technique applied combines the high beam intensity of heavy-ion storage rings with a supersonic gas-jet target equipped with a recoil-ion-momentum spectrometer. In singleelectron capture to fast protons from helium atoms, we have for the first time achieved a complete separation of the kinematic and Thomas transfer mechanisms and are able to perform a quantitative comparison with the many theoretical results on a much more detailed level than what was previously possible. For the process of transfer ionization in proton-helium collisions we have determined the velocity dependence of the Thomas transfer ionization cross section to be the expected vp-11 when the projectile velocity, vp, is sufficiently high. Further, we have determined the velocity-dependent probability for shake-off of the second electron from helium provided that the first one is transferred in a kinematic capture process. Finally, we have considered collisions between protons and hydrogen molecules. Here we have found a strong variation in the cross section for transfer and excitation processes when the angle between the direction of the incoming projectile and the internuclear axis of the target molecule is varied. The variation can be explained as a result of quantum mechanical interference related to the two indistinguishable atomic centers of the molecule.