The onset of

see formula (1) in TD69.pdf

where

see formula (2) in TD69.pdf

By varying T

Laserâ€“cluster interactions fall into two broad categories. One involves the interaction with a very low density cluster medium and the other with a dense cluster medium. The former provides an approximation to the interaction of intense laser pulses with single clusters, which is important for understanding the physics without the complications introduced by macroscopic effects. The latter is required for applications where a high density of clusters is needed to produce a high energy-density plasma, or where macroscopic effects are essential to the process. The study of these two density regimes demands quite different experimental approaches. To allow the laser pulses to interact with a very low density of clusters, the laser is focused many hundreds of nozzle diameters below the nozzle into a cluster beam of density of order 10

See Also

**clustering**and the size of clusters produced can be described by an empirical scaling parameter,*Î“*^{*}, known as the Hagena parameter [16-TD69.pdf]:see formula (1) in TD69.pdf

where

*d*is the nozzle diameter (in mm),*a*the expansion half-angle (x = 45Â° for sonic nozzles, a < 45Â° for supersonic),*p*the backing pressure (in mbar), T_{o}_{o}the pre-expansion temperature (in Kelvin) and*k*, the condensation parameter, is a constant related to bond formation (k_{He}= 3:85 while k_{He}= 5500 17-TD69.pdf). Gas-jets with the same I* tend to form clusters of the same average size.**Cluster formation**is a statistical process and therefore there is usually a relatively broad distribution of cluster sizes [17â€“19-TD69.pdf]. In the massive condensation regime, where nearly all the atoms have condensed into clusters of greater than ~100 atoms, the average number of atoms per cluster hNci scales approximately as [17,20-TD69.pdf]see formula (2) in TD69.pdf

By varying T

_{o}and p_{o}, it is possible to control the value of I* to engineer a cluster medium of arbitrary average density and cluster size. Optical Rayleigh scattering provides a convenient technique for the in situ measurement of average cluster sizes [21â€“23,78-TD69.pdf page 311]. [TD69.pdf, page 311] (This is the same process Keely used and is employed in diesel injectors.)**Dense versus diffuse cluster targets**Laserâ€“cluster interactions fall into two broad categories. One involves the interaction with a very low density cluster medium and the other with a dense cluster medium. The former provides an approximation to the interaction of intense laser pulses with single clusters, which is important for understanding the physics without the complications introduced by macroscopic effects. The latter is required for applications where a high density of clusters is needed to produce a high energy-density plasma, or where macroscopic effects are essential to the process. The study of these two density regimes demands quite different experimental approaches. To allow the laser pulses to interact with a very low density of clusters, the laser is focused many hundreds of nozzle diameters below the nozzle into a cluster beam of density of order 10

^{10}cm^{-3}that is produced with a skimmer and differential pumping arrangement. Interactions with dense cluster media are more straightforward. The laser is focused a few nozzle diameters beneath the nozzle of the gas jet, where the density of clusters can be as high as 5 x 10^{16}cm^{-3}.See Also

**3.14 - Vortex Theory of Atomic Motions****13.04 - Atomic Subdivision****atomic****Atomic Cluster X-Ray Emission****Atomic Clusters****Atomic Force****atomic mass****atomic number****atomic theory****atomic triplet****atomic weight****Debye length****Debye length in a plasma****Debye length in an electrolyte****diatomic****Etheric Orbital Rotations****Figure 13.06 - Atomic Subdivision****Force-Atomic****Formation of Atomic Clusters****Inert Gas****Interaction of Intense Laser Pulses with Atomic Clusters - Measurements of Ion Emission Simulations and Applications**TD69.pdf**InterAtomic****Laser Cluster Interactions****Law of Atomic Dissociation****Law of Atomic Pitch****Law of Oscillating Atomic Substances****Law of Pitch of Atomic Oscillation****Law of Variation of Atomic Oscillation by Electricity****Law of Variation of Atomic Oscillation by Sono-thermism****Law of Variation of Atomic Oscillation by Temperature****Law of Variation of Atomic Pitch by Electricity and Magnetism****Law of Variation of Atomic Pitch by Rad-energy****Law of Variation of Atomic Pitch by Temperature****Law of Variation of Pitch of Atomic Oscillation by Pressure****Models of Laser Cluster Interactions****monatomic****Nanoplasma****Plasma****Plasma holes****Quasi-neutrality****Quasi-neutrality and Debye length****Violation of quasi-neutrality**