# Presentation: 184418

## AST 558:  Graduate Seminar - "Prospects for Fusion Energy"

- •  These seminars will cover both the science and the engineering issues for various fusion concepts, and show how these reactor issues affect the fusion science we do today.
- •  Lectures and background material will be posted
- 			_[http://fire.pppl.gov/ast558_2005.html](http://fire.pppl.gov/ast558)_
- •  Please send questions, comments and additional background material to dmeade@pppl.gov

## Slide 2

## AST 558:  Graduate Seminar - "Prospects for Fusion Energy"

- February 14 	Recent JET Experiments and Science Issues -  Strachan
- February 21  	Advanced Tokamaks FIRE to ARIES - Meade
- February 28  	The ARIES Power Plant Studies – Jardin
- March 7         	IFE basics and NIF  -  Mark Herrmann(LLNL)
- Midterms and Spring Break
- March 21       	The FESAC Fusion Energy Plan - Goldston
- March 28       	Fusion with High Power Lasers  –  Sethian(NRL)
- April 4          	ITER Physics and Technology-  Sauthoff
- April 11         	Stellarator Physics and Technology - Zarnstorff
- April 18         	“New” Mirror Approaches for Fusion - Fisch
- April 25         	ST Science and Technology –  Peng
- May 2          	FRC Science and Technology - Cohen

## A Brief History of Fusionand Fusion Basics

- AST 558
- Dale Meade
- February 7, 2005

## Fusion Fire Powers the Sun

**Fusion Fire Powers the Sun**

**Can we make Fusion Fire on earth?**

## Elements and Issues for a Fusion Power Plant

## Requirements for Development of Fusion

- •  General issues understood very early
- •  Reactor plasma conditions (nE ≈ 3x1020m-3s, Ti ~ 20 keV, Q ≥ 25) - confinement (turbulence), plasma heating
- • Neutron Wall Loading ~ 4 MWm-2 (for economic attractiveness)
- 	- material damage ~ 40 dpa/yr with low radioactive waste
- 	- tritium breeding (TBR > 1) to complete the fuel cycle
- •  Fusion Power Densities ( ~ 5 MWm-3, ––>   p ~ 10 atm)
- 			 = 〈p/ Bc2, MHD stability and coil engineering
- •  Plasma Wall Interaction -
- 			~ 2 MW m-2 thermal load on wall
- 			low impurity levels, low tritium retention (< 0.5 kg-T)
- •  High-duty cycle, essentially steady-state

## Fusion in the Really Early Days (1930s)

- • **1928** - Concept of fusion reactions providing energy radiated by stars proposed by  R. Atkinson and F. G. Houtermans, Physik, **54**, No 9-10, (1929).
- • Australian scientist Sir Mark Oliphant is regarded as the discoverer of the process of fusion in 1932.
- • **1932** - Fusion reactions discovered in the laboratory
- 	Lord Rutherford felt possibility of fusion power using beam - solid target approach was “moonshine.”
- • **1935** - Basic understanding of fusion reactions - tunneling through Coulomb barrier- **fusion requires high temperatures** - Gamov et al
- • **1939** - Hans Bethe develops fusion power cycle for the stars. Nobel prize

## Early Fusion -

-     * 1932 - Mark Oliphant discovered helium 3 and tritium, and that heavy hydrogen nuclei could be made to react with each other.
-     * 1939 - Hans Bethe won the Nobel Prize in physics (awarded 1968) for quantitative theory explaining fusion
-     * 1947 First kiloAmp plasma created by a team at the Imperial College, London, in a doughnut shaped glass vacuum vessel. Plasmas are entirely unstable and only last fractions of seconds.
-     * 1951 - Argentina publicly claimed that they had harnessed controlled nuclear fusion (these claims were false), sparking a responsive research effort in the U.S.
-           o Lyman Spitzer started the Princeton Plasma Physics Laboratory (or PPPL) which was originally codenamed Project Matterhorn - most early work was done on a type of magnetic confinement device called a stellarator.
-           o James Tuck, an English physicist, began research at Los Alamos National Laboratory (LANL) under the codename of Project Sherwood, working on pinch magnetic confinement devices. (Some people claimed that the project was named Sherwood based on Friar Tuck)
-           o 1952 Edward Teller expanded hydrogen bomb research at Lawrence Livermore National Laboratory (LLNL)
-     * 1952 - Cousins and Ware build a small toroidal pinch device in England, and demonstrate that instabilities in the plasma make pinch devices inherently unstable.
- 1954-1958: The ZETA -Zero Energy Toroidal (or Thermonuclear) Assembly device at Harwell
-     * 1952 - 1 Nov, Ivy Mike shot of Operation Ivy: The first detonation of a hydrogen bomb, yield 10.4 megatons.
-     * 1953 - pinch devices in the US and USSR attempt to take the reactions to fusion levels without worrying about stability. Both report detections of neutrons, which are later explained as non-fusion in nature.
-     * 1954 - ZETA stabilized toroidal pinch device starts operation in England built at Harwell south of Oxford.
-     * 1958 - American, British and Soviet scientists began to share previously classified fusion research, as their countries declassified controlled fusion work as part of the Atoms for Peace conference in Geneva (an amazing development considering the Cold War political climate of the time)
-     * 1958 - ZETA experiments end. Several firings produce neutron spikes that the researchers initially attribute to fusion, but later realize are due to other effects. Last few firings show an odd "quiet period" of long stability in a system that otherwise appeared to prove itself unstable. Research on pinch machines generally dies off as ZETA appears to be the best that can be done.
-     * 1967 - Demonstration of Farnsworth-Hirsch Fusor appears to generate neutrons in a nuclear reaction.
-     * 1968 - Results from the T-3 Soviet magnetic confinment device, called a tokamak, which Igor Tamm and Andrei Sakharov had been working on - showed the temperatures in their machine to be over an order of magnitude higher than what was expected by the rest of the community. The Western scientists visited the experiment and verified the high temperatures and confinement, sparking a wave of optimism for the prospects of the tokamak, which is still the dominant magnetic confinement device today, as well as construction of new experiments.

**Early Fusion -**
- http://www.answers.com/topic/timeline-of-nuclear-fusion

## Inertial Confinement Fusion (1940s-early 50s)

- •  Late **1940s** - first ideas on using fusion reactions to boost A bomb yields.
- •  **1950** Teller given approval to develop Super (H-bomb), two stage concept developed - second stage driven by radiation
- •  **1952** Greenhouse/Cylinder - 1951 test of radiation compression of 1 cm D-T pellet.  First US H-bomb, Mike (liquid D2) 1952, exploded “It’s a boy”, followed by a series of tests including Bravo (solid-LiD) 1954 at Bikini Atoll (MNR on observer ship exposed ~ 1R dose).
- • **1950s** Soviet weapons program catches up to US in 1953. Oleg Lavrentiev, Soviet Army sergeant, proposes H-bomb concept to Beria in 1950, and gridded electrostatic confinement for fusion.  Sent to Sakharov and Tamm, who conceive tokamak.
- •  References - Dark Sun by Richard Rhodes, Soviet Program Book
-    History of Soviet Fusion, V. D. Shafranov, Physics-Uspekhi 44(8) 835-865 (2001)

## Toroidal Magnetic Confinement (1940s-early 50s)

- • **1940s** - first ideas on using a magnetic field to confine a hot plasma for fusion.
- •  **1947** Sir G.P. Thomson and P. C. Thonemann began classified  investigations of toroidal “pinch” RF discharge, eventually lead to ZETA, a large pinch at Harwell, England 1956.
- •  **1949** Richter in Argentina issues Press Release proclaiming fusion, turns out to be bogus, but news piques Spitzer’s interest.
- • **1950** Spitzer conceives stellarator while on a ski lift, and makes proposal to AEC ($50k)-initiates Project Matterhorn at Princeton.
- •  **1950s** Classified US Program on Controlled Thermonuclear Fusion (Project Sherwood) carried out until 1958 when magnetic fusion research was declassified.  US and others unveil results at 2nd UN  Atoms for Peace Conference in Geneva 1958.

## Toroidal Confinement-Simple Torus

-    particles to drift vertically
- 	***v***D = (***F***/Ze)X***B***/B2   = ***B***X*********B***/ZeB2
-              = kT***B***X*********B***/ZeB2
- • Charge separation at the edges produces a downward E field that drives outward drift of plasma
-    (both +, -) and field lines.

- Must find toroidal ***B*** geometries that do not allow charge separation

- • Plasma in a simple torus doesn’t have an equilibrium

- •  Can also use an energy principle W =  ∫ (B2/2 + p)dV, compare W before and after a displacement.

***B***

**.**

***B***

## Toroidal Confinement-The Figure 8 Stellarator Solution 

- • The opposite side of the torus is twisted 180% out of the plane causing field lines to effectively spiral connecting the top edge to the bottom edge allowing electron flow along the field lines to short out the ***E*** driven by*********B***.

- Toroidal Confinement-The Figure 8 Stellarator Solution

- • This configuration was the basis for the first stellarator experiments, and the first stellarator power plant studies.
- • The original Figure 8 configurations had very small plasma volume (closed magnetic surfaces) relative to the magnetic field volume.  Spitzer’s original internal reports on this are very interesting. Some modern configurations use a non-planar magnetic axis.

- + +

- - -

- - -

- + +

*E*

*E*

*********B***

***B***

***B***

## Toroidal Confinement-The Helical Coil Stellarator Solution 

- • This idea was the basis for the Model C stellarator, which had a race track shape with an l = 3 winding (trefoil) on one U bend and an l =2 winding (ellipse) on the other.  One straight section had a toroidal divertor and the other had an ICRF launcher.

- Toroidal Confinement-The Helical Coil Stellarator Solution

***i******/2************= #pol/# tor***

- The flexibility of Model C allowed for simple tests of ICRF heating and the divertor but turned out to be a curse for the magnetic surfaces - transitions from U-bends to straight sections generated large magnetic islands.

## Toroidal Confinement-The Tokamak Solution 

- • Spiraling field lines generate a magnetic surface- guaranteed for an axi-symmetric configuration. Nested magnetic surfaces formed radially outward from a singular line -the magnetic axis.
- • Collisions or finite resistivity allows a small ***E*** to exist that drifts the plasma outward where it fills the next magnetic surface- this is Pfirsch-Schluter diffusion, adds to classical diffusion.

- Toroidal Confinement-The Tokamak Solution

- The challenge is to drive the toroidal plasma current efficiently.

## Fusion Reactions of Interest for Fusion Power

**D****+****  +  Li****6****        ––>      2 ****4****He     +     22.4 MeV**

## Fusion Cross Sections and Reaction Rates

- Pf/Vol ~ nDnT<v>Uf  , <v> ~ T2 near 10 kev
-          ~ n2T2  ~ pressure2

## There are Three Principal Fusion Concepts

## Muon-Catalyzed Fusion - Jackson and Alvarez (1957)

**Muon-catalyzed fusion** is a process that allows fusion at room temperature. Although it does produce fusion, it does not currently provide anywhere close to _breakeven_ energy. In muon-catalyzed fusion, _deuterium_ and _tritium_ nuclei form atoms with _muons_. The muons orbit very close to the nuclei, shielding the positive charge of the nuclei so the nuclei can move close enough to fuse. The main problem with muon-catalyzed fusion is that muons are unstable, and hence, there needs to be some cheap means of producing muons, and the muons so produced must be arranged to catalyze as many reactions as possible before decaying. As J.D. Jackson recognized in his seminal 1957 paper [1] , the real problem with muon-catalyzed fusion is that there is a non-vanishing probability (about 1%, actually) that the muon would "stick" to the alpha particle (a Helium-4 nucleus) that results from the _deuterium_ and _tritium_ fusion, removing the muon from the catalysis process. Even if the muon were absolutely stable, it could only catalyze about 100 fusions before sticking, about a factor of 5 too few to provide _breakeven_ energy.
- [1]  J.D. Jackson, “Catalysis of Nuclear Reactions between Hydrogen Isotopes by m- Mesons”, Physical Review 106 (2), 330-339 (1957).
-  [2]  L.W. Alvarez et al., "Catalysis of Nuclear Reactions by Mu Mesons," Phys. Rev. 105(1957):1127-1128.
- See also R. Kulsrud PPPL recent papers

## Plasma Requirements for a Burning Plasma (Lawson Criteria)

- J. D. Lawson, Secret Internal Memo 1955,
- J. D. Lawson, Proc. Phys. Soc. B, V 70, p 6, (1957)

## Status of Laboratory Experiments - Lawson Diagram 

- •  Ti required for fusion has been achieved, but needs 10x nE
- •  Achieved nE ≈ 1/2 required for fusion, but needs 10xTi
- •  After 50 years, MFE is 10% of the way.
- •  Requirements depend on plasma profiles, impurities, synchrotron radiation, etc
- •  Similar curves for ICF but some bremsstrahlung absorption.

## The First Tokamak Reactor Design ~ 1955

- • Tamm (1951) and Sakharov (1952) - first discussed with the West at Geneva 1958 after declassification.
- • Objective: intermediate goal of producing fissionable material

- • Parameters of MTR (a **D-D** reactor )
- 	- collisional heat loss,
- 	-  T = 100 keV,  n = 1020m-3
- 	- Ba = 10 Tm,  H2O Cu coils
- 	-  = 1, B = 5 T, ap = 2 m, R0 = 12m
- 	- Pfusion = 880 MW
- 	- would produce 100 g-T per day, or 80 times that of 233U
- 	   major reason for interest was possibility of material for H or A bombs

- Ref: History of Soviet Fusion, V. D. Shafranov, Physics-Uspekhi 44(8) 835-865 (2001)

- Better from Sakharov Works

## The First Stellarator Reactor Design ~ 1955

- •  In 1954, Spitzer et al commissioned a study of the reactor potential of the stellarator - Model D.  The device was a large figure 8 with a divertor in each U-bend. H2O Cu coils
- • Parameters of Model D (D-T reactor):
- 		- confinement assumed to be OK
- 		- T~10 keV, n ≈ 1021 m-3,
- 		-  = 0.24, B = 7.5 T, ap = 0.45 m, R0 = 24m
- 		- Pfusion = 17 GW (90 MWm-3), Pn = 6 MWm-2, Pelec = 4.7 GW

## The Early 1960s - The Depths of Despair

- •  The first stellarator experiments in the late ’50s were plagued with instabilities. Stellarators were limited by fluctuations causing “pump out, Bohm Diffusion or anomalous diffusion.”
- •  Model C was built to reduce complications of impurities (divertor) and wall neutrals ( a = 5 cm).  Experiments in 1961-66 confirmed Bohm diffusion.

- Bohm flux

- KMY Thesis-Phys Fluids **10**, 213 1967

## The Mid 1960s - First Stabilization of Interchange in Mirror

- •  The first mirror in the late ’50s were plagued with instabilities. Mirrors were afflicted by “interchange instabilities.”
- •  1962  New ideas emerge to stabilize the plasma. Linear multipole coils added to simple mirror create a min-B  well to stabilize the interchange.

- Bmult

- Ioffe - IAEA Proceedings Plasma Physics and Contolled Fusion  **1**, 39,1965

## The Mid 1960s - Bohm Barrier Broken in a Torus

- •  1962 - Toroidal Multipoles built to test min ∫ dl/B stabilization. ∫ dl/B is the volume of a flux tube. *********p ******.********* ∫ dl/B  > 0 for stability.

## The Late 1960s - The Tokamak Emerges

- •  Tokamaks were driven forward as a sequence devices resulting in T-3 at Kurchatov,  B= 4T, a= 0.20m, R = 1.0 m with Ip < 200 kA. Ohmically heated.
- •  T-3 soft X-ray and diamagnetic loop measurements presented at the 1968 IAEA in Novosibirsk indicated Te ≈ 1 keV and E/Bohm ≈ 50.  These results were challenged by PPPL as being due to runaway(or slideaway) electrons.

- •  In an unprecedented example of Soviet- West collaboration, a team from Culham took a Thomson Scattering system to T-3.  In less than a year, results were obtained and presented at Dubna 1969.

- •  Within 6 months, Model C stellarator was converted to the Symmetric Tokamak (ST) that led to ATC (1973), PLT (1975), PDX(1979) and TFTR(1982).

## 1973 Oil Embargo - Energy R&D Explodes

## TFTR - Before D-T 

- July 1973 DOE proposes D-T burner to be built at ORNL - a S/C ignition machine FIBX  parameters??
- Dec 1973  PPPL counter proposal for TCT -”If all you want is neutrons” - intense beam heating, conservative, simplest
- July 1974 DOE announces PPPL has won
- Dec 1975 PLT starts operation
- Mar 1976 TFTR Construction project started
- Aug 1978 PLT Ti = 5.5 keV, no Trapped Ion mode
- Dec 24, 1982  First TFTR Operation -  ~50 kA
- Feb 1986  Record n using pellet injection, still stands in 2005
- Jun 1986  Super shots emerge Record Ti, Pdd, fbs etc
- ~ 1990 Evidence for ITG modes starts accumulating using BES- kr<<1, Ti/Ti ≈ 3-4 n/n, first blob plots, Ti(0) ~ Ti(a) - marginal stability

## Next Lectures 

-  February 14 	Recent JET Experiments and Science Issues -  Strachan
-  February 21  	Advanced Tokamaks FIRE to ARIES - Meade