Ablation cooling

Covering the ablator with CMC, e.g. C/SiC, avoids the ablator erosion process. At the same time the ablator cools the CMC down to a range which is not detrimental to it. The analyses conducted up to now clearly show that even significantly higher heat and dynamic pressure loads can be coped with. 

We use laser photofragment spectroscopy to study the vibrational and electronic spectroscopy of ions. Our photofragment spectrometer is shown schematically in Eig. 2. Ions are formed by laser ablation of a metal rod, followed by ion molecule reactions, cool in a supersonic expansion and are accelerated into a dual TOE mass spectrometer. When they reach the reflectron, the mass-selected ions of interest are irradiated using one or more lasers operating in the infrared (IR), visible, or UV. Ions that absorb light can photodissociate, producing fragment ions that are mass analyzed and detected. Each of these steps will be discussed in more detail below, with particular emphasis on the ions of interest. 

In LIBS analysis, a pulsed laser is focused on the gem surface. The laser energy ablates a small amount of gem material which burns in a short-lived plasma. As the plasma cools, excited electrons decay into lower-energy orbitals, releasing energy in the form of photons in the ultraviolet-visible-infrared range. This light is collected by optic fiber, diffracted, and recorded as a spectrum, generally between 200 and 1000 nm. 

Furthermore, to analyze biological tissues of plants or thin sections of human brain tissues or ice cores, cooled laser ablation chambers have been developed and utilized in different application... 

The experimental arrangement of LA-ICP-MS using a powerful laser ablation system coupled to a double-focusing sector field ICP-MS (Element, Thermo Fisher Scientific, Bremen) is shown in Figure 5.22. A cooled laser ablation chamber using two Peltier elements in serial connection... 

Figure 5.22 Schematic of laser ablation inductively coupled plasma mass spectrometer a laser ablation system (wa velength 213 nm) is coupled to a double-focusing sector field ICP-MS (Element, Thermo Fisher Scientific, Bremen). The cooled laser ablation chamber using two Peltier elements was developed in the author s laboratoryJ26 (M. V. Zoriy, M. Kayser, A. Izmer, C. Pickhardt and J. S. Becker, Int. J. Mass Spectrom., 242, 297 (2005). Reproduced by permission of Elsevier.)...

Figure 6.23 Experimental arrangement of solution based calibration using a micronebulizer (DS-5, CETAC) inserted in a cooled laser ablation chamber for imaging of thin sections of brain tissue. (/. S. Becker et ai, Anal. Chem. 77, 3208 (2005). Reproduced by permission of American Chemical Society.)...

An analytical procedure has been proposed for precise uranium isotope ratio measurements in a thin uranium layer on a biological surface by LA-ICP-MS using a cooled laser ablation chamber.125 One drop of uranium isotope standard reference materials NIST, 350, NIST 930, of our isotopic laboratory standard CCLU 500 (20p.l, U concentration 200 ng 1) and of uranium with natural isotopic pattern were deposited on the leaf surface and analyzed by LA-ICP-MS at well defined laser crater diameters of 10, 15, 25 and 50 p.m. A precision for measurements of isotope ratios in the range of 2.1-1.0% for 235U/238U in selected isotope standards was observed whereby the precision and the accuracy of isotope ratios compared to the non-cooled laser ablation chamber was improved.125... 

Ablation means removal of material from the surface of an object by vaporization, chipping, or other erosive processes. The term occurs in Space Physics [5]. In space vehicle design, ablation is used to both cool and protect mechanical parts and/or payloads that would otherwise be damaged by extremely high temperatures. A low-density EPDM rubber is a fire stopping and fire proofing product that can be ablative in nature. 

A closely related method is that of Boley (B8), who was concerned with aerodynamic ablation of a one-dimensional solid slab. The domain is extended to some fixed boundary, such as X(0), to which an unknown temperature is applied such that the conditions at the moving boundary are satisfied. This leads to two functional equations for the unknown boundary position and the fictitious boundary temperature, and would, therefore, appear to be more complicated for iterative solution than the Kolodner method. Boley considers two problems, the first of which is the ablation of a slab of finite thickness subjected on both faces to mixed boundary conditions (Newton s law of cooling). The one-dimensional heat equation is once again... 

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