# Presentation: 942371

## Innovative Confinement ConceptsIn a Burning Plasma Era

**Lawrence Livermore National Laboratory**
** ****Livermore, CA 94526**
**Fusion Power Associates**
**Washington, DC**
**November 19-21, 2003**

- Work performed under the auspices of the U. S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

**E. Bickford Hooper**

## The ICC Program –– endorsed by every recent planning effort and review of Fusion Energy Sciences

**The Fusion Energy Sciences Program has had many planning efforts and reviews in the past 5 years, both internal and external –– all have recognized the importance of a strong ICC Program**
_**NRC Burning Plasma Assessment Committee**_**: “All the elements of the U.S. fusion program –– advancing plasma science; developing fusion energy science; technology, and ****plasma confinement innovations****; and pursuing fusion energy science and technology as a partner in the international effort –– are essential and coupled.**
**My thesis:  ****Excellent science is being done by the ICCs, motivated both for its own sake and as a path to a better fusion energy source**
**Presented here are:**
**•****	****ICC Program overview**
**•****	****Science issues cross-cutting the ICCs**
**•****	****Some thoughts on strengthening the ICCs**

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## ICC Program supports many concepts

|   | Tokamak innovations & physics | Spherical torus | Stellarator | Self-organized | Pulsed high-dens., other |
| --- | --- | --- | --- | --- | --- |
| POP |  | NSTX ($35M) | NCSX ($16.7) | MST ($5.0M) |  |
| Concept Exploration | Electric Tok.
HBT-EP
Resistive-wall stab.
Tokamak trans. phy.
LTX (CDX) | Pegasus
HIT-II | HSX
CTH
QPS | RFP support
Spheromak
   (SSPX,  HIT-SI, CalTech)
FRC
   (TCS, SSX, Ion Ring, Magneto-comp., Misc.)
 | Mag. Target Fusion
   (FRX-L, MTF sup., stand-off driver)
LDX
Flow Pinch (ZAP)
Mary. Centr. Exp.
Magneto-Bern. Exp.
Inert. Elect. Conf.
CTIX |
| CE BUDGET | $4.1M | $1.4M | $3.7M | $6.5M | $4.6M |

**“****Strong external field”**

**“****Exploratory”**

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## ICC experiments and supporting theory/modeling are a focus of talent at many fusion laboratories

| Universities | National Labs and Industries |
| --- | --- |
| Auburn | LANL |
| CalTech | LLNL |
| Columbia | ORNL |
| Cornell | PPPL |
| MIT | AFRL |
| Swarthmore | GA |
| UC Davis |  |
| UCLA |  |
| U. Maryland |  |
| U. Texas |  |
| U. Washington |  |
| U. Wisconsin |  |

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## The ICC program is a vital link in developing the future workforce for the fusion energy sciences program

**The NRC panels on *****Burning Plasma Assessment***** and on the *****Assessment of the DOE OFES Program***** both identified the need for a continuing influx of high-quality students to meet future workforce needs **
**	****ICC experiments at universities are a significant source of students**
**	****Experiments at the national labs support many graduate students through ****	****collaborations with the universities**
**A survey before the March, 2003 budget-planning meeting demonstrated the strength of student training in the ICC-CE experiments:**
**	****Number of undergraduate students (part time) in past 2 years****	****58**
**	****Number of graduate students in past 2 years****	****	****	****61**
**	****Number of recent PhDs awarded****	****	****	****	****12**

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## Peer review is used to determine scientific quality

**PoP programs are reviewed by panels, with each panel member submitting a personal, confidential report**
**•****	****These reviews focus on science and on progress towards the energy goal**
**•****	****The results have been highly positive**
**•****	****The science focus is strengthened with advice for enhancing research on important issues**
**CE programs are reviewed on a 3-4 year cycle by 3 or more anonymous scientists**
**•****	****This year, 12 renewal proposals were submitted**
**	****–****	****8 received excellent or very good ratings and were funded**
**	****–****	****2 received 1-year close out funds**
**	****–****	****2 received 1-year funding and will need to re-compete for future funds**
**•****	****6 (of 26) new proposals were funded**
**The peer review process is working well and helping to ensure the quality of science in the ICC program**

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## Many cross-cutting science issues are addressed by the ICCs

**ICCs contribute to many science issues in plasma and fusion **
**•****	****These experiments also motivate interactions between fusion science and other scientific disciplines**
**The 2003 Budget Meeting survey found that 82 refereed papers were published by the CEs in the past 2 years**
**A few examples illustrate the strength of science in the ICCs**

**•****	****Magnetic reconnection, magnetic turbulence and chaos in self-organized systems**
**•****	****Effects of flow and flow-shear in suppressing instabilities**
**•****	****Stability limits to plasma pressure**
**•****	****Quasi-symmetry in three-dimensional systems**
**•****	****Magnetic thermal insulation in wall-supported plasmas**

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## Magnetic reconnection is a fundamental process in astrophysical plasmas and in several ICC experiments

**ICC experiments observe reconnection in a broad range of plasmas, broadening the basis for understanding the physics **
**•****	****ST**** – a strong external toroidal magnetic field at low aspect ratio  **
**	****–****	****Reconnection processes are similar to larger aspect-ratio tokamaks **
**	****–****	****At the lowest aspect ratios modes are similar to the spheromak **
**	****–****	****Coaxial helicity injection of current requires reconnection as spheromak.**
**•****	****RFP**** – a moderate external magnetic field, a safety ratio less than one.  **
**	****–****	****Study of tearing modes and the resulting transport of current from the ****	****	****ohmically driven core has elucidated dynamo physics **
**	****–****	****Understanding allowes stabilization, increasing energy confinement.**
**•****	****Spheromak**** – no external toroidal magnetic field, reconnection drives current.  **
**	****–****	****Understanding allows tearing mode suppression, increased energy ****	****	****confinement.**
**•****	****FRC**** – no toroidal magnetic field and no tearing in the conventional sense.  **
**	****–****	****Plasmas formed in a regime intermediate to the FRC and spheromak ****	****	****quickly transform to one or the other by reconnection processes.**
**Development of new resistive MHD codes is strengthening our ability to understand the physic of reconnection in these experiments**

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## Improved understanding of magnetic reconnection processes –– used to improve energy confinement in MST and SSPX

**MST**
**(U. WISC.)**

**SSPX**
**(LLNL)**

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## NSF and DOE have established a Physics Frontier Center in plasma physics to advance laboratory and astrophysical studies of reconnection and related processes

**Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas**
**•****	****Key feature: Bring together laboratory plasma-fusion physicists and astrophysicists to attack common problems**
**Focus on six coupled topics**
**	****Dynamo effects, magnetic reconnection, angular momentum transport, anomalous ion heating, chaos and transport, magnetic helicity conservation**
**Six institutions including 4 experiments**
**•****	****U. Wisconsin (MST)**
**•****	****Princeton (MRX)**
**•****	****Swarthmore (SSX)**
**•****	****LLNL (SSPX)**
**•****	****U. Chicago**
**•****	****SAIC**
**Supported by computation using NIMROD (fusion) and FLASH (ASCI) codes**

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## Effects of flow and flow-shear in suppressing instabilities

**Role of flow shear in suppressing instabilities important to tokamak thermal barriers at edge and in core**
**It also is important in many ICC experiments:**
**•****	****NSTX – Tokamak physics applied at low aspect ratio**
**•****	****ZAP – Shear flow stabilization in a linear z-pinch – experiment is motivated by MHD computational modeling**

**•****	****MCX – Strongly rotating plasma with rotational shear stabilization**
**•****	****Magneto-Bernouli experiment – New equilibrium states with a strong sheared velocity**
**•****	****HBT-EP – Plasma stabilization by conducting wall, rotation, and feedback**
**•****	****RWM – Stabilization of resistive wall modes by rotating walls**
**These experiments provide a broad basis for understanding the physics of plasma rotation and rotation shear in plasma stability**

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## Stability limits to plasma pressure

**Spherical torus (NSTX, Pegasus, HIT-II) – Obtaining high beta by stabilization of MHD modes at low aspect ratio**
**Tokamak (HBT-EP) – Stabilization of MHD modes by conducting walls, rotation and feedback to obtain high beta**
**ET – Finding a path to high beta in a large tokamak**
**Levitated dipole (LDX) – Innate stability in an axisymmetric dipole field – exploring fundmental pressure limits in magnetized plasmas**

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## Quasi-symmetry in 3 dimensional systems

**Stellarator experiments are exploring the effects of “quasi-symmetry” in three dimensional geometries.  (In quasi-symmetry, particle motion can be described in terms of two generalized spatial dimensions.)**
** •****	****NCSX (under construction) – Quasi-axisymmetry**
**•****	****HSX – Quasi-helical symmetry**
**•****	****QPS (conceptual design) – Quasi-poloidal symmetry (related to linked mirror concepts)**
**•****	****CTH – Stability and disruptions due to current in the stellarator configuration**

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## Magnetic thermal insulation in wall supported plasmas

**Magnetized target fusion**
**•****	****A target plasma – FRC, spheromak, . . .  – compressed to fusion conditions with a magnetic field providing thermal insulation – separating heat flow from magnetic support of the pressure**
**Experiments have been conducted on a FRC target and on imploding liners**

**Planned compression experiments will be in a new, high-density parameter space – expanding our understanding of heat-flow suppression by magnetic fields, MHD stability, drift waves, etc.**
**•****	****This work provides a bridge to high-energy density science**

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## Opportunities to strengthen the ICCs (1)

**(A) Budget issues**
**1996**** Report of the *****FESAC-SciCom Review Panel on Alternate Concepts***
**•****	****Defined the program and levels of experimentation –– Concept Exploration, Proof-of-Principle, Proof of Performance & Optimization, Fusion Energy Development, Fusion Power Demonstration Plant****	**
**•****	****CEs –– experiments costing less than $5M/year and/or theory that**
**	****–****	****Strive at establishing the basic feasibility of a concept**
**	****–****	****Explore phenomena of interest and benefit to other concepts**
**Today, the largest CE experiment is funded at $2.5M**
**PoPs were envisioned to cost $5M-$30M**
**–****	****MST is funded only at $5M**
**Given inflation, these levels are low and make it difficult to achieve scientific progress to the depth needed to move to the next step.**
**Recommendation: Close the “funding gap” – Improve the funding of lead CEs and MST**

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## Opportunities to strengthen the ICCs (2)

**(B) Cross-cutting diagnostics for the Ces – to strengthen the science**
**•****	****The CEs are limited in diagnostic capability**
**Recommendation: Establish a diagnostic program focused on the ICCs**
**•****	****Goal:  Improve the scientific output of the CEs –– Perhaps key diagnostics could be portable and moved among several experiments to generate cross-cutting results**
**(C) Theory and Modeling initiative for the ICCs **
**•****	****Theory and modeling needs strengthening for the ICCs**
** ****	****–****	****T&M is key to understanding and interpreting experimental results**
**	****–****	****T&M can also provide guidance in conducting experiments**
**Recommendation: Provide funding opportunities explicitly supporting the CEs, both to interpret specific experiments and to apply the understanding across the portfolio**
**Both efforts would strengthen scientific coupling to the PoPs, tokamaks, and burning plasmas**

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## Summary –– The Innovative Confinement Concepts are significant contributors to plasma and fusion science 

**The ICCs are addressing fundamental science which is also important to the tokamaks and to burning plasmas**
**The science is strong and guided  by peer-review**
**	****As we move forward, we need to encourage the best science we can**
**	**** –– ****We should further strengthen scientific accountability, including ****	****	****developing measures of progress towards our goals and of ensuring ****	****	****the quality of the research.**
**The experiments and supporting theory/modeling contribute to allied areas of science and technology, as called for by the NRC**
**The ICCs attract students to the Fusion Science Program, helping address the need for future scientists and engineers**

**The ICC program should be strengthened in the Burning Plasma era  **
**	****It provides breadth, scientific insight and knowledge, and opportunities for innovation –– helping to build a strong base for future Fusion-Energy Sciences**

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