The Burning Plasma Experiment in Magnetic Fusion: What it is and how to do it S. C. Prager University of Wisconsin February, 2004

What is a burning plasma? A self-sustaining, self-heated plasma; High temperature maintained by heat from fusion; Analogous to a burning star

Magnetic confinement Two approaches to fusion energy inertial confinement, magnetic confinement international effort since 1958, development of plasma physics as a new field, now ready for frontier of burning plasmas, new challenge for international collaboration

Burning Plasmas Fusion power density in sun ~ 300 Watt/m 3, in burning plasmas experiment ~10 MWatt/m 3 plasma physics challenge to Understand a burning plasma Create a burning plasma

A burning plasma requires a large experiment Large, but “domestic-scale” (~$1B) FIRE or Larger, “international-scale” (~$5B) ITER either Choices: domestic vs international, large vs larger

International agreement to build ITER is almost complete ITER partners:China European Union Japan Russian Federation South Korea United States

Outline Burning plasmas - physics challenges Experimental options - ITER, FIRE US perspective

The fusion reaction D + T n +  10 keV 14 MeV3.5 MeV The Fusion Challenge Confine plasma that is hot (100 million Kelvin) dense (~10 14 cm -3 ) well-insulated (~1 sec energy loss time) several atmospheres

Status of Fusion Research More than half way there, judging from Plasma parameters Physics understanding Timetable

Huge advance in plasma parameters year fusion power

The burning plasma regime is a reasonable extrapolation from current experiments

Establishing the physics basis Fusion plasma physics developed for example, control of turbulence and energy loss understanding of pressure limits We are ready for a burning plasma experiment

A burning plasma is self-heated by alpha particles D + T n +   particles trapped in plasma,  particles heat plasma Generates large amount of fusion power

prior plasma experiments Mostly operated without fusion fuel - no tritium Plasmas heated by external means Exceptions - JET (EU) and TFTR (Princeton) generated 16 MW for 1 sec alpha particle heating, but weak ITER will produce 500 MW for 300 sec 350 MW for 3000 sec

Why burning plasmas? New physics New technology Demonstration of fusion power

Burning Plasma Physics New physics from alpha particles Effects on stability and turbulence Alpha heating and burn control

Effect of alpha particles on plasma stability Kinetic energy of alpha particles Plasma waves Loss of alpha particles Plasma cools

The Alfven Wave in an infinite, uniform plasma v phase = v Alfven where v Alfven ~ v phase B Phase velocity spectrum

in a torus v phase waves driven by wave-particle resonance Alpha particles excite wave, Wave scatters alpha particles out of plasma

Alpha Heating and Burn Control temperaturereaction rate thermal stability

add a little alpha physics, temperaturereaction rate Alfven waves loss of alphas heating by alphas

temperaturereaction rate Alfven waves loss of alphas heating by alphas turbulence transport etc add some more physics A burning plasma is a strongly coupled system Alpha ash accumulation resonance

Burning Plasma Technology Plasma technology Materials for high heat fluxes High field magnets Plasma control tools Nuclear technology Blankets for breeding tritium Materials for high neutron fluxes

Experimental Approaches to Burning Plasmas FIRE Fusion Ignition Research Experiment Burning, but integration later US based (~ $1B) ITER International Thermonuclear Experimental Reactor Integrates burning and steady state International partnership (~ $5B)

ITER Characteristics strongly burning: 500 MegaWatts fusion power gain ~ 10, ~ 70 % heating by alphas Near steady state: 300 to > 3000 seconds, many characteristic physics time scales. technology testing, power plant scale Strongly burning plasmas in near steady-state conditions

plasma current ~15 Meg Amps, magnetic field ~5 Tesla/SC, temperature ~ 100 million Kelvin, density ~ m -3

The History of ITER 85discussions begin (Reagan/Gorbachev summit) Conceptual Design Activities (European Union, Japan, Soviet Union, US) Engineering Design Activities 99US withdraws Design of reduced cost ITER (50%) 02Four sites proposed (Canada, France, Japan, Spain) 03US, China, S. Korea join negotiations 03Sites in Canada, Spain eliminated

Current Status Stalemate on site EU, Russia, China favor French site Japan, S. Korea, U.S. favor Japanese site Hopefully resolved in upcoming months Ready to build, negotiations underway on the site

Proposed ITER Sites Cadarache, France Rokkasho, Japan

Approximate ITER schedule Select site2004 Authorize construction Construction to first plasma~ 8 years Begin operation~2015 End operation~2035

FIRE Characteristics strongly burning: 150 MegaWatts fusion power gain ~ 10, ~ 70 % heating by alphas quasi-stationary : ~ seconds, several characteristic physics time scales Strongly burning plasmas in quasi-stationary conditions FIRE is comparable in size to existing tokamaks

FIRE plasma current ~8 Meg Amps, magnetic field ~10 Tesla (Cu), temperature ~ 100 million Kelvin, density ~ 5 x m -3

FIRE and the International Program Envisioned as part of multi-machine strategy Burning plasmas in FIRE Steady state in non-burning plasma (e.g., KSTAR in S. Korea, JT-60 SC in Japan) Integrate at later stage, employing new knowledge and innovation from full fusion research

FIRE Status Design scoping studies underway National effort > 15 participating institutions Preparing to start design in 2005 Can be sited at one of the existing US labls

The US strategy for a burning plasma experiment recommended by US fusion community, not necessarily the government strategy Join ITER If ITER does not go forward, proceed with FIRE

Summary A burning plasma experiment would be a huge step forward in plasma science, and establish the scientific feasibility of fusion energy ITER is a unique international science project, international from conception to execution FIRE is an attractive option if ITER should not move forward

Extra Slides

The Role of International Collaboration ( in executing a large project) The good Cost sharing: essential beyond some cost Sharing of ideas, even in project conception International political support: provides stability International management and execution: a useful experiment, facilitates additional joint activities

The challenges Joint international management and decision-making (site selection, cost-sharing, procurement,…….) Need for international political support (need approval and sustainment from multiple governments) International partnership to build a multi-billion dollar science facility may be without precedent

Fusion community perspective Ready/anxious to study burning plasmas Neutral to whether international or domestic in management The net result of the political pluses and minuses in unknown Any burning plasma experiment will have strong int’l collaboration Any burning plasma experiment will have huge scientific benefit for all nations; and establish the scientific feasibility of fusion energy.

Why Fusion Energy Research? For fundamental plasma physics For fusion energy Clean - no greenhouse gases, no air pollution Safe - no catastrophic accidents Inexhaustible - fuel for thousands of years Available to all nations

The US Strategy for Burning Plasmas based on Three community workshops A 2 week community technical assessment Recommendations of 40 person FESAC panel Recommended by the Fusion Energy Sciences Advisory Committee (Sept, 02) The strategy is the strong consensus of the fusion community

Basis for the strategy ITER and FIRE are each attractive options for the study of burning plasma science. Each could serve as the primary burning plasma facility, although they lead to different fusion energy development paths Because additional steps are needed for the approval of construction of either FIRE or ITER, a strategy that allows for the possibility of either burning plasma option is appropriate

Recommended Strategy for US Join ITER negotiations ITER will be constructed? Join ITER project; if no go, then build FIRE US Participates in ITER Terminate FIRE project Build FIRE, yes No Notes: advance FIRE design until US ITER decision recommended conditions for US participation, set time deadline for US ITER decision (~ 7/04)