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Cosmic-ray and X-ray ionisations in molecular gas produce a weak far-ultraviolet flux through the radiative decay of H2 molecules that have been excited by collisions with energetic electrons (the Prasad-Tarafdar mechanism). I consider the…

Astrophysics · Physics 2009-10-31 Mark Wardle

This study reports a low-frequency alternating current (AC) power supply as a novel approach for generating low-pressure capacitively coupled Ar-O2 plasma, offering advantages in cost, compactness, and operational simplicity, which are…

Plasma Physics · Physics 2024-05-10 Niaz Wali , W. W. Xiao , Q. U. Din , N. U. Rehman , C. Y. Wang , J. T. Ma , W. J. Zhong , Q. W. Yang

In this paper, electromagnetic emissions produced by a beam-plasma system are investigated using particle-in-cell simulations for the particular case when the typical transverse size of both 100 keV electron beam and produced plasma channel…

Plasma Physics · Physics 2019-07-24 V. V. Annenkov , I. V. Timofeev , E. P. Volchok

We have studied radiofrequency capacitively coupled plasmas in pure O2 using single mode laser cavity ringdown spectroscopy of oxygen atoms at 630 nm. The absolute atom densities and translational temperatures were determined over a range…

Plasma Physics · Physics 2026-03-13 Shu Zhang , Andrey Volynets , Garrett A. Curley , Jean-Paul Booth

The generation of very high quality electron bunches (high brightness and low energy spread) from a plasma-based accelerator in the three-dimensional blowout regime using self-injection in tailored plasma density profiles is analyzed…

Accelerator Physics · Physics 2017-11-29 X. L. Xu , F. Li , W. An , P. Yu , W. Lu , C. Joshi , W. B. Mori

We demonstrate optical guiding of high-intensity laser pulses in long, low density hydrodynamic optical-field-ionized (HOFI) plasma channels. An axicon lens is used to generate HOFI plasma channels with on-axis electron densities as low as…

We present a 5-37 micron infrared spectrum obtained with the Spitzer Space Telescope toward the southeastern lobe of the young protostellar outflow HH211. The spectrum shows an extraordinary sequence of OH emission lines arising in highly…

Astrophysics · Physics 2009-11-13 A. Tappe , C. J. Lada , J. H. Black , A. A. Muench

High-harmonic generation (HHG) normally requires a careful adjustment of the driving laser intensity (typically $10^{14} - 10^{15}$ W/cm$^2$) and gas medium parameters to enable good phase matching conditions. In contrast with conventional…

We report the controlled injection of near-isolated micron-sized liquid droplets into a low temperature He-Ne steady-state rf plasma at atmospheric pressure. The H2O droplet stream is constrained within a 2 mm diameter quartz tube. Imaging…

For production of low temperature plasmas with low collisionality, 2.45GHz microwave power up to 20kW is injected perpendicularly to the toroidal field at very low toroidal field Bt

Hydroxyl (OH) is expected to be abundant in diffuse interstellar molecular gas as it forms along with $H_2$ under similar conditions and within a similar extinction range. We have analyzed absorption measurements of OH at 1665 MHz and 1667…

The generation of intense, femtosecond-scale X-ray pulses is crucial for probing matter under extreme temporal and field conditions. Current chirped-pulse amplification (CPA) techniques in free-electron lasers (FELs), however, face…

Accelerator Physics · Physics 2025-06-02 Mingchang Wang , Li Zeng , Bingbing Zhang , Qinghao Zhu , Xiaozhe Shen , Xiaofan Wang , Qinming Li , Weiqing Zhang

Creating extended, highly homogeneous plasma columns like that required by plasma wakefield accelerators can be a challenge. We study the propagation of ultra-short, TW power ionizing laser pulses in a 10-meter-long rubidium vapor and the…

We demonstrate experimentally that hydrodynamic optical-field-ionized (HOFI) plasma channels can be generated at kHz-scale pulse repetition rates, in a static gas cell and for an extended period. Using a pump-probe arrangement, we show via…

Plasma Physics · Physics 2022-03-04 A. Alejo , J. Cowley , A. Picksley , R. Walczak , S. M. Hooker

An experimental study of laser driven electron acceleration in N2 and N2-He mixed gas-jet target using laser pulses of duration ~60-70 fs is presented. Generation of relativistic electron beam with quasi-thermal spectra was observed at a…

Plasma Physics · Physics 2020-01-08 D. Hazra , A. Moorti , S. Mishra , A. Upadhyay , J. A. Chakera

Atomic physics was revolutionized by the development of forced evaporative cooling: it led directly to the observation of Bose-Einstein condensation, quantum-degenerate Fermi gases, and ultracold optical lattice simulations of condensed…

Atomic Physics · Physics 2015-06-11 Benjamin K. Stuhl , Matthew T. Hummon , Mark Yeo , Goulven Quéméner , John L. Bohn , Jun Ye

This thesis is about the designing and constructing a microwave ion source. The ions are generated in a thermal and dense hydrogen plasma by microwave induction. The plasma is generated by using a microwave source with a frequency of 2.45…

Plasma Physics · Physics 2015-03-19 Kamil Çınar

Radio-frequency discharges are performed in low magnetic fields (0-10 mT) using three types of helicon-wave exciting antennas with the azimuthal mode number of $|m|$ = 1. The most pronounced peak of plasma density is generated in the case…

Plasma Physics · Physics 2007-05-23 Genta Sato , Wataru Oohara , Rikizo Hatakeyama

Studies employing nonlinear interactions of THz pulses are nowadays a promising scientific research field. To capture these phenomena, THz pulses with energy ranging from hundreds of \muJ to the mJ level are necessary. However, techniques…

We derive stringent constraints on the persistent source associated with FRB 121102: Size $10^{17}$ cm $<R<10^{18}$ cm, age $<300$ yr, characteristic electron energy $\varepsilon_e\sim0.3$ GeV, total energy $\sim10^{49}$ erg. The hot…

High Energy Astrophysical Phenomena · Physics 2017-06-28 Eli Waxman