# Presentation: 801757

## 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/m3,
- in burning plasmas experiment ~10 MWatt/m3

- 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 MeV	3.5 MeV

- _The Fusion Challenge_
- Confine plasma that is
- 	hot (100 million Kelvin)
- 	dense (~1014 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

- _The Alfven Wave_

- _in an infinite, uniform plasma_
- 		vphase = vAlfven    where vAlfven ~

- vphase

- B

- Phase velocity spectrum

## vphase

- _in a torus_

- vphase

- _waves driven by wave-particle resonance_

- Alpha particles excite wave,
- Wave scatters alpha particles out of plasma

## Alpha Heating and Burn Control

- temperature

- reaction rate

- thermal stability

## add a little alpha physics,

- temperature

- reaction rate

- Alfven waves

- loss of alphas

- heating by alphas

## etc

- temperature

- reaction 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, 

- plasma current ~15 Meg Amps, magnetic field ~5 Tesla/SC,
- temperature ~ 100 million Kelvin,  density ~ 1014 m -3

## The History of ITER

- 85			discussions begin (Reagan/Gorbachev summit)
- 88 - 91	Conceptual Design Activities
- 			(European Union, Japan, Soviet Union, US)
- 92 - 98	Engineering Design Activities
- 99			US withdraws
- 98 - 01	Design of reduced cost ITER (50%)
- 02			Four sites proposed (Canada, France, Japan, Spain)
- 03			US, China, S. Korea join negotiations
- 03			Sites 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 site				2004
- Authorize construction		2004 - 5
- 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:  ~ 20 - 40 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 1014 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)