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X-Ray Lasers
Published in Hitendra K. Malik, Laser-Matter Interaction for Radiation and Energy, 2021
Several options such as pump laser pulses or electrical discharges are used for achieving the highly ionized plasma. Variation in features of the generated SXRLs such as the output energy, optical coherence, and duration can be achieved. When electrical discharge is used for obtaining the optical gain in plasma, the laser generated is the fast capillary discharge SXRL whereas the use of long laser pulses results in quasi-steady state (QSS) SXRLs. The generation of an SXRL is also seen by the interaction of circularly polarized pulses of ultrashort duration with plasma. The methods that are commonly used for plasma excitation, which is crucial for the generation of the X-ray laser, are the capillary discharge SXRL and the transient collisional excitation (TCE) SXRL.
Symbols, Terminology, and Nomenclature
Published in W. M. Haynes, David R. Lide, Thomas J. Bruno, CRC Handbook of Chemistry and Physics, 2016
W. M. Haynes, David R. Lide, Thomas J. Bruno
RPH2, R2PH and R3P (R not equal to H) are called primary, secondary and tertiary phosphines, respectively. [5] Phosphonium compounds - Salts (and hydroxides) [R4P]+X- containing tetracoordinate phosphonium ion and the associated anion. [5] Phosphonium ylides - Compounds having the structure R3P+C-R2 R3P=CR2. Also known as Wittig reagents. [5] Phosphorescence - The process by which a molecule is excited by light to a higher electronic state and then undergoes a radiationless transition to a state of different multiplicity from which it decays, after some delay, to the ground state. The emitted light is normally of longer wavelength than the exciting light because vibrational energy has been dissipated. Photoelectric effect - The complete absorption of a photon by a solid with the emission of an electron. Photon - An elementary particle of zero mass and spin 1. The photon is involved in electromagnetic interactions and is the quantum of electromagnetic radiation. Photon stimulated desorption (PSD) - See Techniques for Materials Characterization, page 12-1. Pinacols - Tetra(hydrocarbyl)ethane-1,2-diols, R2C(OH)C(OH)R2, of which the tetramethyl example is the simplest one and is itself commonly known as pinacol. [5] Pion - An elementary particle in the family of mesons. Pions have zero spin and may be neutral or charged. They participate in the strong interaction which holds the nucleus together. pK* - The negative logarithm (base 10) of an equilibrium constant K. For pKa, see Acid dissociation constant. Planck constant (h)* - The elementary quantum of action, which relates energy to frequency through the equation E = h. Planck distribution - See Black body radiation Planck function - A thermodynamic function defined by Y = -G/T, where G is Gibbs energy and T thermodynamic temperature. [2] Plasma - A highly ionized gas in which the charge of the electrons is balanced by the charge of the positive ions, so that the system as a whole is electrically neutral. Plasmon - A quantum associated with a plasma oscillation in the electron gas of a solid. Point group* - A group of symmetry operations (rotations, reflections, etc.) that leave a molecule invariant. Every molecular conformation can be assigned to a specific point group, which plays a major role in determining the spectrum of the molecule. Poise (P) - A non-SI unit of viscosity, equal to 0.1 Pa s. Poiseuille's equation - A formula for the rate of flow of a viscous fluid through a tube:
Laser ablation for material processing
Published in Radiation Effects and Defects in Solids, 2022
M. Cutroneo, V. Havranek, A. Mackova, P. Malinsky, L. Silipigni, P. Slepicka, D. Fajstavr, L. Torrisi
Figure 1 depicts two acceleration schemes used for laser-driven generation of ion beams: backward plasma acceleration (BPA) and forward plasma acceleration (FPA). The BPA employs thick (∼1 mm) targets, light and heavy ions are emitted in the backward direction (i.e. opposite to the laser beam direction) (see Figure 1(a)). The FPA employs thin (∼0.1–100 µm) targets and usually light ions are emitted mostly forward (i.e. same direction as the laser beam) and mostly along the normal to the target surface (see Figure 1(b)). In both cases, a laser beam focused on a solid target produces hot highly ionized plasma. The plasma emits UV and X radiations, neutral particles as well as electrons and ions. A part of the absorbed laser energy is converted into a directed plasma beam, that is, the beam containing ions surrounded with an electrons cloud.
Effects on RCS of a perfect electromagnetic conductor sphere in the presence of anisotropic plasma layer
Published in Waves in Random and Complex Media, 2018
A. Ghaffar, M. M. Hussan, A. Illahi, Majeed A. S. Alkanhal, Sajjad Ur Rehman, M. Y. Naz
In last few decades plasma has been considered as most attracted material due to its dissipative behavior and great optical properties [1]. Study of electromagnetic wave interaction with plasma leads to different applications i.e. field of defense technology, aerospace sciences, communication, optical sensing, and many more [2]. Plasma consists of highly ionized gasses, also mixture of molecules, free ions, and electrons. Plasma has also been considered as a dissipative medium because a violent collisions of particles occur due to thermal agitation. Plasma behaves as a lossy isotropic medium when we remove the external applied magnetic field with complex permittivity. If magnetic field is applied plasma behave as anisotropic medium and its permittivity transmutes into tensor form which depends on plasma density, collision frequency, and applied magnetic field [3,4]. Electromagnetic wave interaction with plasma in unmagnetized state was studied by Vidmar [5]. The absorption, reflection, and propagation of electromagnetic waves through plasma in unmagnetized state investigated theoretically and concluded that unmagnetized plasma has a capability to absorb the most part of incident electromagnetic waves and can be used in several applications of target protection [5].