Demonstration of Collisionless Interactions Between Interstreaming Ions in a Laser-Produced - Plasma Experiment

Abstract

1(c) to the linear term in the arc tan but one must also take the cubic term in the arc tan.There is a connected term of precisely the same geometry as Fig. 1(c) coming from the cube of the disconnected or two-body parts of the K matrix. Here, however, intermediate states get a 6(E -H Q ) rather than a P[l/(E -H Q )\ It is important to take these two terms together in order to get a finite answer. All other terms are higher order.Putting the C term of Eq. (6) [ Fig. 1(d)] in the linearized arc tan makes a direct evaluation even more difficult, but it is again clear on dimensional grounds that there will be a term in b 3 of the form A" 4 lnX. It has been claimed that b n contains only positive and negative integral powers of A. 10 This does not seem to be the case.It is clear from this analysis that terms beyond A" 4 lnA in b s require a full solution of the threebody problem since they involve terms of 0(1) in E in Eq. (6).Turning to the w-body cluster coefficient b m there will again be terms connected by statistics, which presumably can be summed into statistical corrections to lower-order terms and terms connected by scattering. It is easy to see that the leading low-energy contribution to the n-body K matrix goes as A/E n ' 2 with A proportional to a"" 1 . In Eq. (3) again the linear term in the arc tan will dominate. Thus one finally gets as the lead-A high-density, high-temperature plasma is produced when a Q-switched laser is focused onto a small solid target. Within a few nanoseconds the thermal energy of the plasma is converted into kinetic energy of radial expansion. l If a low-pressure ambient gas is present, then radiation from the laser-produced plasma photoionizes the gas and the laser-produced plasma streams radially outward through the resulting ambient plasma. We report observations of mo-ing low-temperature contribution to b n from nbody scattering a term proportional to (a/A)"" 1 (if there are no w-body bound states). There are terms of higher order in 1/A m and (l/A m )ln*A, but one does not need solutions of the full w-body problem until one gets to terms of order 1/A 3n " 5 .

Experimental Observation of Thin-shell Instability in a Collisionless Plasma

“…The laser-target interaction was enclosed in a gas cell filled with pure nitrogen at a controlled pressure of ∼10 −1 mbar. Hydrodynamic simulations using the code HYADES  (Larsen & Lane 1994) indicate that the gas becomes fully ionized within 100 ps from the start of the laser irradiation by the Xrays emitted from the target (Dean et al 1971), resulting in a stationary plasma with an electron density and temperature of 1 . Moreover, the Coulomb logarithm for electron-electron and ion-ion collisions are of the order of 6 and 11, respectively, indicating a characteristic timescale for collisions of t~36 ns ee and t~600 ns ii , respectively.…”

Search for the Ultimate Energy Source

“…Such shocks had been predicted from theory. My experiment was successful and resulted in two papers published in Physical Review Letters [19,20]. A surprise bonus came to our group when we observed very large signals on a magnetic probe diagnostic designed by John Stamper.…”

“…The Knotec panel was told by DOE to consider only two budget levels for the fusion program: an upper level of $275 million and a lower level of $200 million. The Knotec subcommittee held two meetings in December 1995 (at PPPL and General Atomics) and made its report to the full FEAC (chaired by Robert Conn) at its meeting January [18][19]1996 in Washington, DC [80].…”

Emergence of kinetic behavior in streaming ultracold neutral plasmas

“…Because of the increasing mean free path with particle kinetic energy, the situation can already change for mean free path on the order of or longer than 1% of the length scale of plasma gradients [1]. This gives rise to kinetic effects such as streaming plasmas and non-local transport, which are intensely studied because of their importance in many plasma environments, such as high-density laser-produced plasmas [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] and astrophysical plasmas like the solar wind [19], solar atmosphere [20,21], solar flares [22], and supernovae [23].…”