ARIES Documents -- Meetings ArchiveARIES Conference Call, 6 December 2001
Documented by L. Waganer
Les Waganer informed the group that the next ARIES meeting would be held 10-11 January 2002 in San Diego. Les will be assembling the agenda shortly, so please send him your anticipated presentation title, duration, and special scheduling needs. We intend to start the meeting early on the 10th and complete the meeting around 12 noon on Friday, the 11th, to allow sufficient time to make flight connections. We prefer electronic versions of the presentations be provided to Mark Tillack by January 4, early enough for him to assemble a complete electronic presentation file.
Laila El-Guebaly mentioned she just sent out the FED newsletter. The team noted a lot of positive responses to it.
Farrokh Najmabadi mentioned he is trying to schedule the US/Japan Fusion Reactor workshop to be held at San Diego early in 2002. This is difficult due to the need to accomplish the meeting by a certain time while also minimizing the travel by scheduling the workshop close to the time of the ISFNT conference being held in San Diego on April 7-12. Several other meetings may conflict in this time period.
Farrokh said the ARIES-ST chapters have been finalized and transmitted to the publishers.
Ron Miller has incorporated the recommended target scaling laws including those for the conventional targets into the systems code. He is working to quantify the uncertainty parameters into the code to assess the sensitivity of the system performance to key input variables.
Ron mentioned he was investigating the analogy of the manufacture of light bulb shells to IFE targets. He said that the bulbs could be manufactured at the rate of 33/s.
Susana Reyes gave a brief summary of the radioactivity and toxicity of the candidate target materials, namely mercury (Hg) and lead (Pb). Activation results show that both Hg and Pb qualify as acceptable materials when analyzing the contact dose rates and waste disposal ratings. From the accident analysis perspective, one must distinguish between accidents at the target fabrication facility and accidents at the power plant itself. Regarding accidents at the target fabrication facility, Hg is the most hazardous when estimating doses to the public. However, segregation of the inventory in the plant and optimization of plant layout would make the 1-rem limit goal achievable. In case of accidents involving the power plant primary coolant loop, Pb seems to pose a greater threat due to its higher inventory suspended in the FLiBe coolant flow. From the chemical safety point of view, the similar values of limit concentration in air for public protection do not indicate any of these materials to be a superior candidate. However, mercuryís high saturation concentration in air at normal temperatures makes it a more hazardous option. It has been demonstrated that Hg concentrations leading to an acceptable gaseous release radiological dose would exceed the chemical safety requirements by several orders of magnitude.
Lee Cadwallader noted he has been writing a paper for SOFE on the accident initiating events for HYLIFE.
Chamber Wall Engineering
Said Abdel-Khalik reported that the GT group is conducting an experiment to determine the liquid metal film dynamics on wetted walls with typical chamber geometries, including beam openings and inclined surfaces. One investigation topic is to determine the onset and causing factors for flow separation. Said is working with Ahmed Hassanein on this general topic. Ahmed noted he is analyzing the behavior of thin liquid films when bombarded with x-rays and energetic ions.
RenČ Raffray is also analyzing the behavior of the thin liquid films with the code RECON to determine the recondensation of the film to reestablish a complete film before the next target explosion.
RenČ mentioned that he needed data on the latest ID target spectra to complete the Consistent Overlap Parameter Study. The group mentioned that data was presented in a paper at the recent High Average Power Laser Conference. The data should now be available on the ARIES Web. The data is similar to that provided by Bob Peterson except for knock-on ion effects.
RenČ discussed the need to explore the porous wall in more depth as he considered it to be the only viable sacrificial wall option. But the detailed design approaches and parameters have not been proposed nor agreed upon. These are needed to analyze the response of the underlying porous structure. He intends to propose some design guidelines at the January meeting.
Don Haynes said he is evaluating the wetted wall option when irradiated with both lasers and heavy ion beams. He is using the BUCKY code to analyze the wall response. He asked the group to affirm that the most likely thin liquid wall material is lead. The group agreed lead is a leading candidate at present although all other candidates will be evaluated.
Leslie Bromberg told the group that he has been investigating the feasibility of using the plasma charge state to enhance or enable plasma clearing down to the millitorr pressure regime at desired repetition rates. Leslie said the process needed the base pressures to be in the 5-10 millitorr regime for the process to be feasible. Don Haynes said these were reasonable pressures with wall temperatures of 1000C.
Craig Olson mentioned that the ANS newsletter had an article on HI beams and transport. He also said that Sandia and MRC are working on the self-pinch channel formation and beam transport concept. One key issue is to determine the amount of the erosion on the leading edge of the beam.
Simon Yu discussed the assisted channel formation technique for beam transport. In this concept, the challenge is the design of an insulated beam port insulator to inhibit beam breakdown at the port. It must be well protected from the target blast. Simon said the thick liquid walls would offer good protection, but the thin or dry walls would offer less protection for the insulator. Simon is working on a new configuration and materials that may offer more protection. Dai-Kai Sze mentioned that the breakdown of FLiBe should not be a problem. RenČ will check with someone at UCSD on this issue.
Dale Welch of MRC said he is working on the Z-pinch targets and will have something to report in the future.
Leslie Bromberg said he is working on defining some design algorithms to help design both high-temperature and low-temperature magnets. He is working on magnetic configurations and materials selections.
Chamber Nuclear Analysis
Laila El-Guebaly noted she has been working on activation of candidate hohlraum wall materials and liquid wall impurities, specifically lead, lithium-lead, and tin. One open question was the levels of impurities, especially in tin.
T.K. Mau continues to investigate the effect of liquid metal droplets, et. al., on the nearby mirror surfaces. He still lacks the optical properties of lead to properly assess its influence on the mirror system. He did say that carbon and lead degrade the mirror reflectance, whereas lithium and sodium are rather benign regarding mirror reflectance.
Leslie Bromberg informed the group that he is evaluating the use of a plasma window to isolate both laser and heavy ion beams. A plasma is locally formed that isolates the plasma chamber from the lower vacuum regions in the beamlines. The plasma window can be switched off in a very short time to allow the beams to pass and then be turned back on after the beam passes. However, it works better in the higher-pressure regimes.