Energy fluence

Wave- length Photon energy Relation between energy fluence and photon fluence ... 

Despite these widespread applicahons, ILM is not equally well suited for all classes of analytes. Due to the need for increased laser energies/fluences for the ionizahon/desorption process, ILMs may only be of restricted suitability for some classes of analytes. For example for proteins, an extensive peak broadening caused potenhally by the combination of extended neutral losses (e.g., of ammonia or water) and alkali-ion-adduct formation can be observed. On the other hand, the increased tendency of the ILM to favor sodium and potassium adduct formation makes it ideally suited for the measurement of carbohydrates [38,40], whereas in proteomics, this tendency of adduct formahon is again an unwanted effect. 

Fig. 27.1 Chronic leg ulcers of a 60 years old male patient before and after laser therapy, three sessions per week at energy fluence of 0.5 J cm , He-Ne laser. Duration of ulcer was 16 months...

Figure 2. Threshold energy fluence for the appearance of the tripeptide mass spectrum with distinct chromophore R+ photoion as a function of the UV laser pulse duration (from Ref. 8).

Figure 1. Diagram of the intensity / (W/cm2) vs. duration of laser pulse tp(s) with various regimes of interaction of the laser pulse with a condensed medium being indicated very qualitatively. At high-intensity and high-energy fluence 4> = rpI optical damage of the medium occurs. Coherent interaction takes place for subpicosecond pulses with tp < Ti, tivr. For low-eneigy fluence (4> < 0.001 J/cm2) the efficiency of laser excitation of molecules is very low (linear interaction range). As a result the experimental window for coherent control occupies the restricted area of this approximate diagram with flexible border lines.

In its usual form the critical energy concept is really a critical energy fluence concept and is expressed as... 

In addition to exptl contradictions the critical energy concept is also subject to fundamental theoretical difficulties. For example, as pointed out by Stresau Kennedy (Ref 54a) Macroscopic models, such as Walker Wasley s concept of critical energy fluence and Pastine, Bemecker Bauer s concept of critical thermal energy, do not explicitly address the point that the concentration of the energy in hot spots is essential to initiation, and its consequence, that the temp of the hot spot plays a significant role in the initiation process. It seems that the distribution, rather than the density, of the thermal energy should be expected to be decisive in the initiation process ... 

Idco, simplified expression Eg = 4 P/Sjg when the radiant power is constant over the solid angle considered). For energy fluence rate the SI unit is W It reduces to irradiance, E, for a parallel and perpendicularly incident beam not scattered or reflected by the target or its surroundings. 

Fluence is sometimes used for amount per area, so radiant energy per unit area is the energy fluence (J m-2). 

The term energy per unit area is referred to as the energy fluence (Ref 8). Recalling the Rankin-Hugoniot jump conditions, specifically the mass and momentum equations for a shock, we had derived that... 

The quantity p U [in Eq. (22.14)] is often called the shock impetknce of a material. It increases very slowly with increasing pressure, but over the pressure ranges of general interest (in shock initiation) it can be considered to be nearly constant. Because of this, many workers in the explosives field combine this value into the critical energy fluence and use the term instead as the critical value for initiation. 

The critical energy fluence is a necessary condition for shock initiation of detonation, but is not, by itself, sufficient to describe the whole process in engi-... 

We have seen now that both critical energy fluence as well as pulse duration and magnitude are necessary conditions for shock initiation of detonation, but this is still not sufficient. One additional parameter must be taken into account, and that is the impact shock diameter. 

This effect is seen quite dramatically in data obtained by both Moulard and Wenograd (Ref. 9). In both sets of tests reported, very long shock pulses were used (the flyers were actually cylinders). Therefore, the data are shown only for pressure, not energy fluence. Each data point represents the 50% pressure for detonation versus nondetonation for different diameter flyers. The explosive targets were Composition B, and the flyers were steel. These results are shown plotted in Figure 22.8. 

As you will recall, there must be sufficiently high-energy fluence or P t) and high enough pressure such that the explosive can be initiated in a reasonably short distance from a shock wave input. Electrical constraints limit the practical size (pressure, temperature, time) of the shock obtainable from the bridgewire, and these are such that we require an explosive with very low critical energy fluence, Ec (or and short run distance. PETN, at low density and small... 

As stated earlier, the critical energy fluence, Eq (or P t rid, must be exceeded to detonate an explosive from a shock wave. The pressure of the shock wave as well as its duration from a bursting bridgewire are functions of the burst current (or of the peak burst power). There is a minimum burst current below which we cannot detonate the initial pressing. This minimum burst current is dependent not only on bridgewire parameters, but also upon the properties of the explosive used for the initial pressing. The critical properties of the explosive that affect minimum burst current are those that affect Ec, namely, the density, particle size, and specific surface area of the particles. 

The quantities a, c, f, F, r, and p are the thermal diffusivity, sound speed, heat capacity ratio, bulk viscosity coefficient, shear viscosity coefficient, and density of the sample, respectively and Eo, a, P and Cp are the energy fluence of the laser beam, the optical absorption coefficient, the volume expansion coefficient, and the isobaric heat capacity, respectively, of the fluid. Tlie first and second terms in Eq. 2 describe the time dependences of the thermal and acoustic modes of wave motion, respectively. Since the decays of the acoustic and thermal mode densities back to their ambient values take place on such different time scales (microsecond time scale for acoustic mode and millisecond time scale for thermal mode), they were recorded on the oscilloscope using different time bases. 

In the present paper, effects of wavenumber and energy fluence of a laser, and gas pressure and flow rate of a reactant gas on the enrichment of Si were examined using isotopic selective decomposition of Si2F6 under irradiation of a pulse CO2 laser. The effect of inert gas addition to the reactant on the concentration of "Si was also studied. 

As mentioned, the first property of an effective sensitizer is chemical purity. This simplifies the interpretation of dose- response relationships in a situation made complex hy extra variables including drug-light interval, total energy, fluence rate and especially pharmacokinetics. With a multicomponent sensitizer (such as Photofrin) the rational interpretation of the causes for the overall effect becomes very difficult. 

S. Tajima, K. Komvopoulos, Effect of ion energy fluence on the topography and wettability of low-density polyethylene exposed to inductively coupled argon plasma. J. Phys. D AppL Phys. 39, 1084-1094 (2006)... 

Figure 7.6 Influence of spot size on critical energy fluence to ignition MTV [14].

---