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ARIES Documents -- Meetings Archive

ARIES Conference Call, 22 August 2000

Documented by L. Waganer


Participants:
(ANL) Hassanein
(Boeing) Waganer
(DOE) -
(FPA) -
(GA) Goodin
(INEEL) Petti
(LANL) -
(LBL) -
(LLNL) -
(MIT) -
(NRL) Sethian
(PPPL) Brown, Dahlgren
(RPI) Steiner
(TSI) -
(UCSD) Mau, Miller, Najmabadi, Raffray, Tillack, Wang
(UW) El-Guebaly, Mogahed, Peterson, Sviatoslavsky

Administrative

The dates for the next ARIES-AT and –IFE meeting will be 18-20 September 2000 at PPPL. The first full day will be devoted to completing the ARIES-AT design. Tuesday and Wednesday will be devoted to early definition and results of the ARIES-IFE study. The meeting will conclude around 2-3 p.m. to make airline connections. Steve Jardin is making the meeting arrangements.

Farrokh noted the ARIES Peer Review held on 17 August went very well, with many positive remarks from the reviewers. They said the presentations transmitted the necessary information to the reviewers. The peer review agenda and links to the presentations can be found at http://aries.ucsd.edu/LIB/MEETINGS/0008-ARIES-PEER-REVIEW.

ARIES-IFE Study

Target and Chamber Physics

Bob Peterson has been working with Andy Schmitt to obtain the target physics data to run the BUCKY code for x-ray and debris output (to include both spectra and magnitude). Bob has been using the output spectra from the Sombrero target results as initial input data to the BUCKY code. His current results indicate an output energy of 110 MJ, assuming a 1.3 MJ laser (inferring a gain of 85). An NRL code predicted an output energy of 125 MJ. John Sethian asked if zooming was included and Bob indicated it was. It was asked if current target designs would be analyzed and Bob assured they would be – the Sombrero target data was available and was used to initiate the analysis. Farrokh Najmabadi requested these results be documented and distributed to the team as soon as possible. Les Waganer indicated John Perkins would also be presenting DD and ID target output spectra at the meeting.

Bob reported that Don Haynes has completed a set of analyses to predict the capability of xenon gas at pressures from 5.0 torr to 0.01 torr using the Sombrero target. The preliminary results indicate a chamber pressure as low as 0.05 torr would adequately protect the wall. This compared to the 0.5 torr of xenon recommended previously by Bob in the Sombrero report. It was confirmed that the analysis assumes the prompt x-rays ionize the gas prior to the arrival of the target debris ions.

Chamber Wall Engineering

Mark Tillack said there was nothing to report in the chamber wall engineering.

Chamber Nuclear Analysis

Laila El-Guebaly provided a list of initial parameters to an engineering group following the peer review last week at UCSD. It was decided that it was too early to narrow the choices and determine specific data, but some parametric work could be prepared for the upcoming meeting. She will discuss the lists of initial parameters for both laser and HIB drivers with the ARIES team at the September meeting.

Chamber Clearing

No action reported.

Final Optics

Mark Tillack has completed a preliminary examination of the requirements on the final optic. He recommended the entire optical path be defined for both KrF and DPSS lasers. This would enable a more detailed understanding of the requirements on the final optic performance.

Target Fabrication, Injection, and Tracking

Dan Goodin reported that Ken Schultz has been in contact with Max Tabak at LLNL to define the HI direct drive (DD) target characteristics and expected performance.

Dan noted that GA is working on the conceptual design of a target injection system to be summarized at the September meeting. A conceptual design review of this system will be held at GA at the end of September. As part of the design verification testing, Ron Petzoldt provided a movie to demonstrate separation of two sabot halves to dispense a 4-mm plastic ball that remained stationary. The movie and the sabot description can be seen at http://aries.ucsd.edu/ARIES/FEATURED/sabot.shtml.

GA is also researching the reflectivity of a gold layer to be applied to the DD target.

Dan said that they have been working on the accuracy of target delivery to a point within the target chamber within ± 20 mm (3 sigma, delta X^2 + delta Y^2 + delta Z^2)^0.5 = +/- 20 microns). With a chamber pressure of 0.5 torr, a correction of 22 cm is required along the line of injection. He noted that the magnitude of the correction was not in itself a critical issue, but the consistency of the correction factor from shot-to-shot was. It was noted that if the target is injected at 400 m/s and the laser pulse is 20 ns (long), the target would move 8 mm during the pulse duration.

John Sethian asked if Dan thought chamber gases would condense on the target, but Dan thought they would not significantly condense under these conditions.

System Analysis

Ron Miller has been gathering coding from previous systems code and collecting data to be input into a new or modified systems code. He also has been investigating a software code to evaluate input parameter uncertainty.

Safety and Environmental Analysis

Dave Petti reported no new results in IFE.

ARIES-AT Study

Plasma Physics

TK Mau received the latest modified equilibrium case data from Kessel and was able to obtain a CD scenario using only 2 RF systems over a limited range of parameters around the design point: fast waves for on-axis drive and lower hybrid (LH) waves for off-axis. Since the location of the seed current is sensitive to the plasma profiles, a back-up RF system, such as HHFW, may be needed to cover a wider plasma region to inside the reverse shear layer.

The ARIES physicists had a meeting at GA last Friday to discuss and finalize the plasma analysis findings and conclusions for the report.

  • Steve Jardin has agreed to work with G. Schmidt (PPPL) to do a (computer) run of pellet fueling from the top for ARIES-AT to determine the requirements for the fueling system.
  • There appeared to be some uncertainty as to whether we should have core radiation or SOL radiation to lower (or, more accurately, spread) the heat flux on the divertor plates. GA maintained that the radiative divertor concept might not work, depending sensitively on the up-down magnetic balance, according to Tom Petrie. Mark Tillack said core (or mantle) radiation would not work for ARIES-AT because the first wall has not been designed to take the resulting wall load. Farrokh said that he would arrange a meeting with GA people to resolve this issue.
  • The issue of stabilization of the neo-classical tearing mode (NTM) was discussed. Kessel proposed that LHCD as used in ARIES-AT could be used for this purpose since the CD region is the location of the relevant island. GA maintains that it is not clear if experimental results were for resistive or neoclassical tearing modes and they suggest that ECCD be the driver for stabilization. It was agreed to include both viewpoints in the report.

Engineering

Rene Raffray reported that Xueren Wang has posted new figures on the ARIES web indicating more details of the blanket fabrication process. He is most concerned with the fabrication of the outer blanket segments, comprised of both arcs and straight sections.

Les Waganer mentioned that he is defining the power core maintenance options and comparing the benefits and disadvantages of the different approaches. He will send a draft to Rene to critique.

Laila El-Guebaly said that Paul Wilson was nearly finished with the activation analysis for the LiPb coolant. She will distribute the results shortly. Early results indicate that approximately 40,000 Ci will be generated from the Po210 after 4 FPY with no purification system in place. The release limit goal is 25 Ci. Thus, an on-line purification system for bismuth is required from start of operation.

Tom Brown said that he is almost ready to send the ProEngineer drawings of the coil systems that are compatible with the latest radial build information and other current design changes.

Fred Dahlgren is refining outer TF coil cases to reduce deflections below limits. The latest results still show deflections somewhat larger than desired, but he has potential solutions that are expected to reduce the deflections within desired ranges. PPPL has completed a higher resolution field mapping around the PF coils that indicates the peak radial and vertical fields within the perimeter of the coils vary from 6 to 9.3 Tesla in the outer coils (PF10 - PF14). Coils PF12 and PF13 are the most critical with peak vertical fields of 9.3T near the inner radial edge of the conductor. Since the radial fields are a more benign for these two coils (7-8T), they are considering orienting the conductor plane horizontally and enlarging the coil cross-sections (or increasing the conductor fraction) to reduce the current density in this region. A reduction in current density to 20 kA/cm2 may be required for PF13 and 30 kA/ cm2 for PF12. If the same 15% conductor fraction is maintained, PF13 must be enlarged by about 15 cm in both the radial width and vertical height. This is being evaluated. Since these high fields occur relatively close to the coil surfaces (2-3cm), Leslie Bromberg may have to resolve the current redistribution.

Elsayed Mogahed affirmed that his LOFA and LOCA results from the last meeting are still current and valid.

Safety and Environmental Impact

Dave Petti has been analyzing the ex-vessel LOCA scenario that assumes a free flow of LiPb from the ring header into the surrounding room. The LiPb cools from conduction and radiation to the surroundings. The ventilation system for the rooms is assumed to be isolated by the operator after 1 hour to stop the egress of Pb aerosol containing the Po. His analysis indicates that less than 5 Ci of Po would be released in this accident scenario.

Systems Assessment

Ron Miller has incorporated the latest radial build into the code and completed a new strawman dated 8/8/00. A range of plant factors up to 85% is included. No changes for the new plasma physics, RF design basis, or the radiating mantle have been included at this point.

Ron mentioned that he documented the incremental impacts of significant COE improvements from the ARIES-RS design to the current ARIES-AT design. These data were presented at the recent ARIES peer review and will be presented again at the upcoming ARIES meeting.

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