Call for Community Input

The National Academies Committee for A Strategic Plan for U.S. Burning Plasma Research invites you to submit comments and documents relevant to the Committee's task to provide guidance on the long-term strategy for magnetic confinement-based fusion research.

Comments and documents should be sent using the Community Input Form on the Committee's online location. Input will be accepted in most common formats, e.g. PDF. Please note that all community input received will be posted on the Committee's web site and made available through the Committee’s public access file as required by the Federal Advisory Committee Act

By C.M. Greenfield

ITER news

Following the recent ITER Council’s twentieth meeting on June 21 and 22, ITER released a statement that “rapid onsite construction progress and reports of milestones successfully achieved in delivering components from Members’ manufacturing centers worldwide were two core indicators for the ITER Council to determine that the ITER Project remains on track for success, with full awareness that many challenges remain before completion of construction. Council Members reaffirmed their joint commitment to the mission and vision of the Project.”

The National Academy Burning Plasma study has begun

The National Academies study on “A Strategic Plan for U.S. Burning Plasma Research” is finally underway (http://sites.nationalacademies.org/BPA/BPA_177107), with co-chairs Mike Mauel (Columbia) and Melvyn Shochet (Chicago). The committee held its first meeting in Washington, DC, on June 5, and USBPO Deputy Director Amanda Hubbard and I were privileged to be invited to address the committee. This came as a last minute surprise, and does not supplant our intention to provide input from the US Burning Plasma Organization based on the material you provided in response to calls from topical group leaders.

Amanda and I gave a presentation that responded to three questions from the committee: /resources/ref/USBPO-NAS_20170605.pdf

1. What advancements in fusion science and technology have occurred since the release of the previous Burning Plasma Report (2004)?
2. Have any advancements or developments altered the importance of burning plasma research to the U.S. fusion research program?
3. During the next decade, what are the important scientific and technical problems to be addressed in the U.S. burning plasma research program?

If you want to see our detailed answers to these questions, you’ll have to go look at the presentation. I will say here that the answer to question 2 is “NO.” I don’t think that will surprise any of our readers. I should also mention that due to the rushed nature of this presentation, it was given with the disclaimer that “we have not had time to solicit input from USBPO membership to prepare for this meeting, so this talk should be taken as our personal perspective.”

Moving forward, we will continue to collate the responses we received in recent months toward preparing an undetermined number (my preference is two, but I might be convinced otherwise) of white papers and a presentation for the NAS committee. Chairman Mike Mauel has assured us that the committee will be interested in receiving this input.

There were two other invited presentations made during the public session in the June 5 meeting. Ed Synakowski gave a presentation entitled “Context for an NAS study on burning plasma research and a magnetic fusion strategy” (http://www.firefusionpower.org/NAS_BP-Strategy_synakowski_060517.pdf). During this presentation, Dr. Synakowski urged the committee to “be bold” in its report. I was pleasantly surprised at his rather optimistic comments on the state of ITER and the US role in it. These were echoed by the other presenters, congressional staffers Adam Rosenberg and Emily Domenech.

Rosenberg and Domenech also reminded us of what by now should be a familiar message: Our best chance to maintain a healthy burning plasma field is for the community to speak with one voice. Along those lines, the upcoming U.S. Magnetic Fusion Research Strategic Directions Community Workshop will provide an opportunity for the community to begin trying to reach such a consensus. My understanding is that this will be only the beginning of a longer process aimed at the kind of community unity that has been successful for other scientific fields.

A new FESAC Transformative Enabling Capabilities (TEC) panel is also underway, led by Rajesh Maingi (PPPL) and Arnold Lumsdaine (ORNL), in response to a charge to identify transformational technological developments that could enable future progress. Besides directly advising DOE Fusion Energy Sciences on technology research directions this study will also inform the second phase of the National Academies study. Two public meetings have been held and a third is scheduled for July 19-21.

Plans for APS-DPP conference

Once again, the US Burning Plasma Organization is organizing a contributed oral session on Research in Support of ITER at the 59^th Annual Meeting of the APS Division of Plasma Physics, which will take place in Milwaukee, Wisconsin, October 23-27. As I write this, a subcommittee of the USBPO Research Committee is evaluating the proposals for slot, and the people who have requested those slots should be notified in the next few days.

We are also working to get an exciting speaker for a town meeting on ITER, but do not yet have a firm commitment – so stay tuned.

US Burning Plasma Organization news

With the advent of summer comes the end of terms for four USBPO Council members and five Topical Group leaders. Please watch for an announcement from Susana Reyes, chair of the USBPO Council nominating committee, soliciting your nominations for new Council members. Four Council members are now completing their terms: David Brower (UCLA), Juergen Rapp (ORNL), Jim Terry (MIT), and François Waelbroeck (U Texas). Two of these will be replaced by election (hence the call for nominations) and two by appointment. I should note that our bylaws limit Council membership to no more than two people employed by the same institution. As there are currently two continuing members from Princeton Plasma Physics Laboratory (Chuck Kessel and Stan Kaye) and two from General Atomics (David Pace and Gary Staebler) no further nominations can be accepted for PPPL or GA staff.

Confinement and Transport Topical Group
Saskia Mordijck, Leader, USBPO Confinement and Transport Topical Group

The ITPA Spring 2017 Transport and Confinement Topical Group meeting was held in Princeton, US, on May 1-3 2017, hosted by Princeton Plasma Physics Laboratory. The topics addressed were: ITER H-mode database revision, dependence of momentum/particle pinch on collisionality, Impurity transport, Particle transport during transient H-mode phases by pellets, Developments on neural network simulations, Quasi- linear model validation, Understanding of the LOC-SOC transition and connected phenomenology, Updated ITER Research Plan and T&C related issues, Discussion on organization of ITER physics update work.

The Fall 2017 meeting will be held at VTT, Helsinki, Finland, 3.5 days on September 18-21, 2017. The topics foreseen are:

•     Revision of the ITER confinement database

•     Progress on the intrinsic rotation database

•     L-H transition (joint meeting with the Pedestal and Edge Physics Group)

•     3D effects (joint meeting with the Pedestal and Edge Physics Group)

•     Inward pinch in opaque edge plasmas (joint meeting with the Pedestal and Edge Physics Group)

•     r* scaling of intrinsic torque

•     Threshold and stiffness

•     Edge shortfall

•     Updates from each joint experiment and joint activity

The 18^th meeting of the Integrated Operation Scenarios was held at the ITER headquarters in April 3-6 2017.

An overview of the status of the ITER heating and current drive systems was given by the ITER Organization:

Neutral Beam Injection: The critical parameters for the system have been achieved in separate experiments: full voltage acceleration (Japan) and required current density (Germany). The beams are specified to have 2-7 Hz modulation capability and ±25% beam power variation (the latter to be confirmed by MITICA, Padua). The ITER Council is considering the proposal to install the captive components of a third (but not the actual source) during the construction phase to avoid interruptions after operation.

Ion Cyclotron RF: The second IC antenna is back in the baseline and the first antenna is being considered for the first Pre-Fusion Power Operation (PFPO-1) phase. Modifications of the port to reduce neutron streaming require a redesign of the matching network, which introduces gaps in the frequency range. This should be a problem only for sawtooth control application, but would not impact standard operation at full and near half-field.

Electron Cyclotron Heating and Current Drive: Operation at one-third field (1.8T/5MA) would require gyrotrons at lower frequency. Options under consideration are either dedicating 8 of the 24 gyrotrons to dual frequency, or purchasing gyrotrons at 110GHz to allow breakdown at the second harmonics. Also, thicker windows would be needed.

One-third field (1.8T) operation is now officially included in the research plan as an opportunity to demonstrate H-mode access with 20MW of EC. These plasmas have large ripple and it is not clear what the effect would be on the plasma performance.

Issues with operation at half-field include (1) parasitic absorption of EC at the third harmonic (2) absence of a good heating scheme in hydrogen plasmas (3) hydrogen dilution by pellets in helium plasma should be maintained below 20% for H-mode access and below 10% to avoid IC mode conversion.

A solution to the improvement of the IC absorption would be to increase the magnetic field to 3.3T, but this might limit the radial accessibility of the EC.

Simulations of the synergy between RF waves and fast-ions are being carried on both in Europe and in the US to address some of these issues.

ASDEX-U and DIII-D showed projection of a q_min~1 scenario that may be suitable for steady-state operation. In the former case, inclusion of electromagnetic effects and fast ions in GENE would reproduce the phase with b_N~2.7, which could not be reproduced with TGLF (it could reproduce well the b_N~2 phase).

In the latter case, FASTRAN was used to project to fully non-inductive operation at 8 MA and Q=3.7, but with density above the Greenwald density with the baseline heating system. Achieving Q=5 would require 106 MW of power at 10.8 MA.

Combined control is being tested both in models and experiments. Applications for ITER presented at this meeting include: burn control in stationary conditions (but not entry to burn), simultaneous kinetic and current profile control using models. Density control for ITER is being simulated, including processing of sensors and models for gas puffing, pellets, and pumping.

RAPTOR is now using the QuaLiKiz neural network and is moving towards including impurity transport. The control-based model is being extensively tested in the MST1.

USBPO Public Calendar: 2017

This newsletter provides a monthly update on U.S. Burning Plasma Organization activities. The USBPO operates under the auspices of the U.S. Department of Energy, Fusion Energy Sciences (FES) division. All comments, including suggestions for content, may be sent to the Editor. Correspondence may also be submitted through the USBPO Website Feedback Form.

Become a member of the U.S. Burning Plasma Organization by signing up for a topical group.

Editor: Charles Greenfield (greenfield@fusion.gat.com)