IGNITION CRITERION FOR DENSE, ISOBARIC D-T PLASMAS AND CONSEQUENCES ON ICF DESIGN
The design of high gain ICF targets is strongly influenced by the efficient attainment of thermonuclear ignition. In this connection we have applied the results of a study of D-T ignition in plasmas relevant to ICF, to envisage a set of suitable driver and target parameters. We have then investigated the potentiality of a class of double shell targets, requiring unshaped, moderate intensity laser pulses. To study D-T ignition in conditions close to those achieved in hollow shell implosions, we have analyzed the evolution of a system initially at uniform pressure P-o, and consisting of a cold, dense D-T plasma at density rho-c, containing a hot spot of radius R-o at temperature T-o >= 3 keV and density rho-o < rho-c. In the analysis that follows we will use the equation of state of a perfect gas for the hot spot, and that of a partially degenerate electron gas for the cold fuel, namely, epsilon-o = C-vT-o; epsilon-c = alpha-epsilon; epsilon-d = 3.1 times 10**12 rho-c**2/3(erg/g), and P = (2/3) rho-epsilon everywhere; here alpha is the isentrope parameter; other symbols are of standard use; subscript o indicates quantities at time t = 0. Preliminary results show that medium gain (G +- 100) targets with fuel mass M = 2 / 6 mg, outer shell radius R 1 = 0.4 / 0.6 cm, inner-shell radius +- R-1/3, aspect ratio 40 <= A <= 80, require 2 / 2.5 MJ in a 25 / 50 ns triangular pulse, with 0.53 / lambda <= 2mu (we have taken 0.04 <= f <= 0.4; lower mass and higher aspect ratio correspond to longer wavelength and/or lower f).
Bibliographic Reference: 11TH EUROPEAN CONFERENCE ON CONTROLLED FUSION AND PLASMA PHYSICS, AACHEN (GERMANY), SEPT. 5-9, 1983 IN ENEA REPORT 83.23/CC, PP. 39-42, 1983 WRITE TO ENEA + CENTRO RICERCHE ENERGIA FRASCATI, SERVIZIO STUDI E DOCUMENTAZIONE, C.P. 65 00044 FRASCATI, ROMA (I
Record Number: 1989122052500 / Last updated on: 1987-01-01
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