U.S. Burning Plasma Organization e-News
September 15, 2008 (Issue 24)

CONTENTS

     -- Director's Corner by Jim Van Dam
    -- Reports
         - 14th IPTA meeting on Diagnostics by Réjean Boivin
     --Feature Article
         - First Round ITER First Wall Qualification Mockup Tests at Sandia National Laboratories by Mike Ulrickson
     -- Upcoming 2008 Burning Plasma-Related Events

Dear Burning Plasma Aficionados:

This newsletter provides a short update on U.S. Burning Plasma Organization activities. Comments on articles in the newsletter may be sent to the editor (R. Nazikian rnazikian@pppl.gov) or assistant editor (Emily Hooks ehooks@mail.utexas.edu).

Thank you for your interest in Burning Plasma research in the U.S.!

Director's Corner by J. Van Dam

Fifty years of fusion
This year marks the fiftieth anniversary of the 2nd United Nations Conference on the Peaceful Uses of Atomic Energy, held in Geneva in 1958. At that conference, research results from previously classified national fusion efforts were openly shared for the first time. In a sense, therefore, 1958 marks the beginning of the modern worldwide fusion program, with its emphasis on international collaboration and its awareness of the potential benefit of fusion energy for all humanity.

Several large meetings this fall will be celebrating this fiftieth anniversary event. In September (8-12), the biennial International Congress on Plasma Physics (http://www.triam.kyushu-u.ac.jp/ICPP/), to be held in Fukuoka, Japan, will feature a keynote talk by Roald Sagdeev on “Plasma Physics: Evolution in 50 Years and the Outlook,” a semi-centennial lecture by Atsuo Iiyoshi on “Development of Fusion Science Studies in Fifty Years,” and a concluding plenary talk by Friedrich Wagner on “The Power of Plasmas.” I will be giving an invited talk on “Progress toward Burning Plasmas.” In October (13-18) there will be the 22nd IAEA Fusion Energy Conference (http://www.fec2008.ch/), whose location had been intentionally chosen as Geneva, Switzerland, in order to commemorate fifty years of fusion and mark the entrance of the world program into the burning plasma era with ITER. Then, in November (17-21), the 50th Annual Meeting of the Division of Plasma Physics of the American Physical Society (http://www.aps.org/meetings/unit/dpp/) will be held in Dallas, Texas. This DPP meeting will be a fiftieth celebration of its own history, as well as that of the world fusion program. As noted in last month’s eNews, the USBPO will organize a special Town Meeting on Tuesday evening of that week, with talks that will describe the current scientific and programmatic status of the ITER Project. Please mark your calendars.

US ITER Project Office
The USIPO Technical Advisory Committee (TAC), chaired by Dr. Charles Baker, held its annual meeting in Oak Ridge on August 13-14. On behalf of the USBPO, I attended and presented a talk on “Most Urgent ITER Physics Needs & the ITER Research Plan.” (You can find it posted on the USBPO web site: click on Reference Files, then look down the page for ITER Presentations.) The TAC, during its debriefing at the end of the meeting, commended the US fusion community for its strong and valuable response to addressing ITER urgent R&D needs. The TAC also had some suggestions for how to further enhance the US involvement in the continued development of the ITER Research Plan by involving broadened community input, which the USBPO will take under consideration.

Upcoming ITPA meetings
Each of the ITPA topical groups typically holds two meetings per year. The schedule for the fall meetings this year is given in the table below, compiled by Michiya Shimada (ITER Organization).

Proposed ITPA Meetings in Fall 2008

Topical Groups	Date	Place	Comments
DivSOL	15-18 Sept. 2008	Nagasaki (Japan)	Following ICPP Conference. Host: Prof. T. Tanabe & Prof. M. Sakamoto (Kyushu Univ.)
Pedestal	20-22 Oct. 2008	Milan (Italy)	Following IAEA Fusion Energy Coference. Jointly hosted by Institute of Plasma Physics of CNR and University of Milano-Bicocca. Host: Dr. Paola Mantica
Confinement & Transport	20-22 Oct. 2008	Milan (Italy)
MHD Stability	20-22 Oct. 2008	CRPP (Lausanne)	Following IAEA Fusion Energy Conference. Host: Dr. Ambroglio Fasoli
Energetic Particles
Integrated Operation
Diagnostics	17-21 Nov. 2008	IPR, Ghandinagar (India)	After one day ITER Diagnostics Mtg.
IEA/ITPA Joint Experiment Planning Mtg	11-13 Dec. 2008 (2.5 days)	MIT (USA)	1.5 days of R&D planning + 1.0 day of joint expt planning

The US members of the ITPA and the USBPO topical groups have been asked to work closely to prepare for these meetings. Such preparations include developing the meeting proposals and agendas as well as recommendations for US participants at these meetings. An important topic of discussion at all of these meetings will be an evaluation of the ITER High Priority Research Tasks.

In addition, on December 11-13, 2008, US and international program leaders and ITPA members will meet under the auspices of the various IEA Implementing Agreements for the 7th Annual ITPA/IEA Planning Meeting, to be held at MIT. The main objective of this meeting is to review progress in joint experiments carried out during 2008 and then to present, discuss, and approve proposals for joint experiments in 2009.

Reports

Report on the 14th ITPA meeting on Diagnostics
by Réjean Boivin

The Fourteenth Meeting of the ITPA Topical Group (TG) on Diagnostics was held at CRPP/EPFL, Lausanne, Switzerland, from 14 to 18 April 2008. The meeting was combined with a Progress Meeting on ITER relevant diagnostic developments in Europe, which took place on the 14th of April. Also discussed is the formation in Europe of the domestic agency for ITER, “Fusion for Energy”, charged with project related tasks, versus the EFDA role, now charged with programmatic issues. Diagnostic tasks will be distributed amongst the two entities as appropriate.

Special sessions were devoted to the effect of stray light and wall reflections on optical diagnostics, and on the proposed changes to the requirements for plasma measurements on ITER and the ITER diagnostic system following the design review in 2007.

During the Progress Meeting on ITER relevant diagnostic developments in Europe, European scientists presented work that has been done within the scope of the EFDA Technology Work Programme for diagnostic systems that are expected to be provided by Europe. Additionally, a number of other ITER relevant diagnostic developments in Europe were discussed.

In addition to the special sessions topics, the key topics reviewed and discussed at the TG meeting were:

the progress and plans in meeting the goals of the Physics Voluntary R&D tasks in Diagnostics especially for high priority topics;
developments in the ITER measurement requirements and justifications of those measurements;
review of critical areas of ITER diagnostic design and integration;
the recent progress in ITER relevant diagnostic development and application;
review of the status of key elements of ITER diagnostic design and integration;
review the responses to the action items from the 13th meeting of the ITPA Diagnostic TG and plan future actions;
review progress by the Specialist Working Groups in Diagnostics;
discussion on the date of the 15th meeting of the TG;
planned future activities.

Many discussions took place on high priority (HP) items:

Development of methods of measuring the energy and density distribution of confined and escaping a-particles.
Assessment of the various options for the Vertical Neutron Camera to measure the 2D n/a source profile and asymmetries in this quantity, and assessment of the calibration strategy and calibration source strength needed.
Assessment of the integrated measurement capability of the diagnostic systems relative to the specified measurement requirements.
Determination of life-time of plasma facing mirrors used in optical systems.
Development of requirements for the measurement of dust, and assessment of techniques for measuring dust and erosion.

Item #3 was completed:
An overview was presented of the latest developments in ITER, with a focus on the status of the diagnostics design review and the implications for the ITER diagnostic system. As a result of the changes incorporated by the diagnostic design review, and the follow up activity of the cross party Diagnostic Working Group, the overall technical performance of the ITER diagnostic system has been improved. All former non-credited systems have either been properly included in the diagnostics system and allocated to a Party or dropped. In some cases, only the interfaces or the front end of systems are included due to limitations of the construction credit but the systems concerned, for example the high resolution neutron spectrometer, will not be needed until several years into the operational programme and so can be installed cost effectively later if required. This High Priority item has been successfully concluded and can be taken off the list of HP topics for 2008/2009.

Specific items

A special session was devoted to the effect of straylight and wall reflections on optical diagnostics. One presentation focused on the effects of wall reflections on the operation of the Tore Supra MSE system. The reflections lead to a reduced signal/noise ratio and parasitic lines in the spectrum. The best chords are the ones that look into another port. Various methods are being tested in order to reduce the effect of the reflections including modal decomposition techniques and neutral beam modulation. Although the results are positive more effort is needed. Another presentation argued in favour of using the bidirectional reflectance distribution function (BRDF), widely used in other fields, for standardization of reflection coefficients. The specular reflectance lobe is the most difficult part of the reflectance behaviour to characterise. Using model functions established in the rendering community (i.e. virtual reality models used in computer games), it appears that this lobe is not very important for extended sources like bremsstrahlung, but for edge sources it is. The modelling calculations remain to be confirmed by measurements on at least one set of completely characterised tiles in order to study whether or not in-situ checks of the evolution of the reflectance with exposure to plasma discharges are possible. Since the wavelength dependence of the reflectance is different from that for bremsstrahlung, measuring at several wavelengths should help to assess the impact in the experiment. For edge emission, imaging should be supported by Zeeman spectroscopy to localise the true source of the emission.

The ITER requirements have been updated as part of the ITER design review and accepted into the ITER baseline. In parallel the measurement requirements have been reviewed by the ITPA Divertor & SOL TG in their meeting in January. This has resulted in a number of proposals for changes to the measurement requirements that now need to be reviewed by the ITPA Diagnostics TG and eventually be incorporated in the level 1-measurement requirements and put forward to the IO for inclusion in the Plant Integration Document. The capabilities of various diagnostics for fast particle measurements have been compared with the requirements and a number of suggestions for further research were made, for Collective Thomson scattering, neutral particle analysis and gamma-ray diagnostic systems. A brief discussion took place on the proposals and recommendations put to the attention of the Diagnostics TG by the ITPA TGs on Transport and Steady State Operation.

An overview of the issues in the field of diagnostic integration into ITER was presented with a focus on the impact of the ELM control coils, the blanket manifolds, in-vessel diagnostics, the upper port structure design, the diagnostic racks in the divertor and the diagnostic test bed.

The ITPA Parties reported steady progress in the development of many ITER relevant diagnostic techniques. Some examples of recent work presented at the meeting are: visible/infrared wide-angle viewing system (EU), impurity influx spectroscopy (JA),neutron activation system (KO), Ha spectroscopy (RF) and divertor interferometry (USA).No reports were presented on the work in India and China. New types of radiation-hard Hall probes compatible for measurements in ITER outside the vacuum vessel have been developed in the Ukraine and tested in various EU devices.

The future of the ITPA under the auspices of ITER was shortly discussed as well as the impact of the new set up for the directions of the work of the ITPA Diagnostics TG in particular.

It is proposed to hold the 15th meeting in Gandhinagar, India from 17 – 21 November 2008. The provisional location of the 16th meeting in the spring of 2009 would be in the Russian Federation.

Feature Article

First Round ITER First Wall Qualification Mockup Tests at Sandia National Laboratories
by Mike Ulrickson, Sandia National Laboratory

The US will provide about 20% of the components for the first wall of the International Thermonuclear Experimental Reactor (ITER). The first wall consists of panels roughly a meter square in size made of individual fingers that have beryllium tiles joined to a water-cooled copper alloy heat sink. For those ITER Parties (US, EU, China, Japan, Korea, and Russia) who will supply ITER first wall component, the ITER Organization requires early testing to qualify their manufacturing processes.

Each party is manufacturing two First Wall Qualification Mockups for independent thermal cycling tests, one in the Plasma Materials Test Facility (PMTF) at Sandia National Laboratories and the other in the Czech Republic. Each mockup is approximately 80 x 240 x 84 mm and has three 80 x 80 x 5 beryllium tiles joined to a copper alloy heat sink. The heat sink has two stainless steel channels for water cooling and is joined to a stainless steel backing beam. Testing the quality and reliability of the joint between the beryllium and copper heat sink is the primary objective.

Fig 1. US (left) and EU mockups installed in
EB1200 with copper dummy targets

Fig 2. On screen IR camera display during half
cycle in which the US mockup is heated.

The first round of testing at Sandia, with mockups from the US and the European Union, began April 15 and finished on July 17, 2008. Fig. 1 (above) shows the US and EU mockups installed in PMTF. At Sandia, each mockup received 12,000 cycles with a heat load of 0.875 MW/m2 for 48 seconds and 48 seconds with no heat load. The second stage had 1,000 cycles with 1.4 MW/m2 for 20 seconds and 20 seconds with no heat load. Extensive measurements with calibrated IR, thermocouples and water calorimetry during the test were used to evaluate the absorbed power and uniformity of the heat load. We observed no failures on either mockup. Both the US and EU mockups have passed the first half of the qualification process. The ITER Project has requested a follow-on test of these mockups for 100 additional cycles in which the surface temperature of the beryllium tiles will reach 600°C.

Sandia was selected because EB1200, the large (1.2 MW) electron beam facility in PMTF can apply the appropriate heat load, has a unique set of diagnostics including infra-red and video cameras to monitor the surface of the mockups, and can test targets with beryllium, which requires special handling. The Czech facility has radiant heaters, fewer diagnostics and no direct view of the surface being tested. Testing at the European facility is nearly finished. A second round of testing at Sandia, with mockups from China, Japan, Korea, and Russia, will start in November 2008 and should be complete by mid-March 2009.