High-$beta$ capture and mirror confinement of laser-produced plasmas. Semiannual report, August 1, 1973--January 31, 1974

Technical Report · Thu Jan 31 04:00:00 EDT 1974

DOI:https://doi.org/10.2172/4304105· OSTI ID:4304105

Haught, A F; Polk, D H; Woo, J T; Fader, W J; Tomlinson, R G; Jong, R A; Ard, W B

Experimental studies aimed at improving the reproducibility of the dense, laser produced plasmas were performed. Efforts in this area were concerned with the positioning of the target particle more accurately in the laser focal region and with preventing the premature displacement of the particle from the focal region. To address this latter problem, the single beam laser system of the previous experiments was modified to permit the simultaneous irradiation of the lithium hydride pellet by two opposed laser beams. In addition, the diagnostic capabilities of the present experiment were augmented so that more detailed measurements of the plasma lifetime, density, and energy can be made. A 4 mm microwave interferometer was installed to follow the plasma decay from higher densities. The measured density decay histories were analyzed to give estimates of the plasma lifetime and energy. Independent measures of the time dependence of the plasma radius were obtained from both microwave interferometry and optical streak photography. To measure the energy distribution of the ions which escape through the mirror loss cones, an electrostatic ion energy analyzer was developed. The theoretical effort in support of the experimental program dealt with the solution of the rate equations and Fokker-Planck equations which describe the confined plasmas in the Laser Initiated Target Experiment (LITE). The rate equation analysis of the plasma heating and evolution to steady state with neutral injection using the LITE parameters indicates that a 0.5 Ampere current of 10-keV neutrals with intensity 5 mA/cm/sup 2/ at the target will balance the Coulomb decay and charge exchange losses with the neutral background and will susiain a plasma of density)10/sup 12/ cm/sup -3/. In addition, self-consistent Fokker -- Planck calculations (now including the effects of charge exchange with the background neutrals) were performed to give the time evolution of the particle energies, density, and plasma potential. The design of the neutral beam line for the charge exchange heating and neutral injection experiments was completed. To accommodate the energetic neutral flux while maintaining the necessary high vacuum conditions, a self-consistent calculation, including recycling of the neutral flux from the walls, has shown the need for an enlarged experiment chamber to provide more effective pumping. The criteria on which the designs of the experiment chamber and the neutral beam line are based, are discussed. (auth)

• Research Organization: United Aircraft Corp., East Hartford, Conn. (USA). Research Labs.
• NSA Number: NSA-29-028399
• OSTI ID: 4304105
• Report Number(s): COO--2277-3; UARL-N--921514-20
• Country of Publication: United States
• Language: English

Related Subjects

*LASER-PRODUCED PLASMA-- CONFINEMENT
*MAGNETIC MIRRORS-- CONFINEMENT
*PLASMA-- CONFINEMENT
CHARGE EXCHANGE
FOKKER-PLANCK EQUATION
FUEL PELLETS
HIGH-BETA PLASMA
ION TEMPERATURE
LITHIUM HYDRIDES
N70100* --Physics--Controlled Thermonuclear Research-- Confinement & Heating
N70600 --Physics--Controlled Thermonuclear Research--Production
PLASMA DIAGNOSTICS
RESEARCH PROGRAMS LASER-PRODUCED PLASMA