Optical-Energy Absorption and High-Density Plasma Production

Multiphoton Ionization of Atomic Hydrogen in the Ground State

“…Following perturbation theory and using the nonrelativistic dipole approximation, the differential cross section per atom for multiphoton ionization may be derived and written in the form lm-2l\Tj iK fg u oV' (1) where dv n i/dQ is the differential cross section in cm 2 /sr, for each subshell described by quantum numbers (n, I), The quantity / is the light intensity in W/cm 2 , / 0 = 14.038x 10 16 W/cm 2 , a is the finestructure constant, and a 0 is the Bohr radius. The photon energy Ep 9 the wave number of the emitted electron, k, and the Nth -order matrix element, K fg > are ai * dimensionless multiples of the atomic units.…”

Characteristics of laser induced gas breakdown

“…[1][2][3] However, laser produced plasma from gas breakdown has not been well studied in a view of industrial application. Table 1 shows typical laser parameters for laser ablation and laser induced gas breakdown.…”

Laser-Induced Prebreakdown and Breakdown Phenomena Observed in Cloud Chamber

“…A where sufficient number of iterations were run so that E 0 was B(R) = 4:6(T-2 l22Cu(a/R) u -5C 8 Direct observation of initiating electrons below the threshold for visible breakdown discharge is reported. With the cloud-chamber techniques used, minimum detectable ionization is estimated at 5000 ion pairs/cm 3 .…”

“…Above the visible breakdown threshold, thermal-gradient effects overcome all other sources of droplet formation in the cloud chamber. I N this article the observation of laser-induced prebreakdown ionization 1 -2 and breakdown phenomena [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] in a continuously sensitive cloud chamber [20][21][22] is reported. The nature of the cloud chamber is such that two separate and easily distinguishable effects are produced when the laser power is above and just below the breakdown threshold.…”

“…8 Following laser breakdown, about half of the laser energy is absorbed into a focal volume of about one cubic millimeter. Heat diffuses outward from the focus and upsets the normal equilibrium conditions in the chamber.…”