The Instigator
bencbartlett
Pro (for)
Winning
12 Points
The Contender
RationalMadman
Con (against)
Losing
0 Points

Magnetic confinement fusion is more promising as an energy source than inertial confinement fusion.

Do you like this debate?NoYes+0
Add this debate to Google Add this debate to Delicious Add this debate to FaceBook Add this debate to Digg  
Post Voting Period
The voting period for this debate has ended.
after 2 votes the winner is...
bencbartlett
Voting Style: Open Point System: 7 Point
Started: 9/3/2012 Category: Science
Updated: 5 years ago Status: Post Voting Period
Viewed: 3,678 times Debate No: 25434
Debate Rounds (4)
Comments (3)
Votes (2)

 

bencbartlett

Pro

===Resolution===

“Magnetic confinement fusion, as a whole, holds greater and more immediate commercial promise as an energy source than inertial confinement fusion.” I will argue pro and be supporting the use of magnetic confinement fusion; my opponent will argue the use of inertial confinement fusion (which may include inertial electrostatic confinement systems, if he/she wishes to include that). Obviously, this is a shared burden of proof. The argument pertains particularly to near-future (within the next 100 years or so) commercial viability of fusion as an energy source.

===Rules===

Must be somewhat knowledgeable in the subject to accept.

No trolling/semantics.

5000 character limit, 72 hours to respond, 1 week voting period.

No baseless or unscientific speculation.

R1: Accept

R2: Main arguments (no rebuttal from con yet)

R3: Rebuttal (no response to rebuttal from con yet)

R4: Counter-rebuttal and final statements. No new information or rebuttals.

Failure to comply will result in automatic forfeit.

===Definitions===
Magnetic confinement fusion (MCF): "an approach to generating fusion power that uses magnetic fields to confine the hot fusion fuel in the form of a plasma." [1]

Inertial confinement fusion (ICF): “a process where nuclear fusion reactions are initiated by heating and compressing a fuel target, typically in the form of a pellet that most often contains a mixture of deuterium and tritium. [without the use of magnetic fields]” [2]

Inertial electrostatic confinement fusion (IECF): “a concept for retaining a plasma using an electrostatic field whereby the electrostatic field accelerates charged particles (either ions or electrons) radially inward, usually in a spherical but sometimes in a cylindrical geometry.” [3]

===References===

[1] http://en.wikipedia.org...

[2] http://en.wikipedia.org...

[3] http://en.wikipedia.org...

RationalMadman

Con

In inertial confinement fusion, which is a newer line of research, laser or ion beams are focused very precisely onto the surface of a target, which is a pellet of D-T fuel, a few millimetres in diameter. This heats the outer layer of the material, which explodes outwards generating an inward-moving compression front or implosion that compresses and heats the inner layers of material. The core of the fuel may be compressed to one thousand times its liquid density, resulting in conditions where fusion can occur. The energy released then heats the surrounding fuel, which may also undergo fusion leading to a chain reaction (known as ignition) as the reaction spreads outwards through the fuel. The time required for these reactions to occur is limited by the inertia of the fuel (hence the name), but is less than a microsecond. So far, most inertial confinement work has involved lasers.

Recent work at Osaka University's Institue of Laser Engineering in Japan suggests that ignition may be achieved at lower temperature with a second very intense laser pulse guided through a millimetre-high gold cone into the compressed fuel, and timed to coincide with the peak compression. This technique, known as 'fast ignition', means that fuel compression is separated from hot spot generation with ignition, making the process more practical.

In inertial confinement fusion, which is a newer line of research, laser or ion beams are focused very precisely onto the surface of a target, which is a pellet of D-T fuel, a few millimetres in diameter. This heats the outer layer of the material, which explodes outwards generating an inward-moving compression front or implosion that compresses and heats the inner layers of material. The core of the fuel may be compressed to one thousand times its liquid density, resulting in conditions where fusion can occur. The energy released then heats the surrounding fuel, which may also undergo fusion leading to a chain reaction (known as ignition) as the reaction spreads outwards through the fuel. The time required for these reactions to occur is limited by the inertia of the fuel (hence the name), but is less than a microsecond. So far, most inertial confinement work has involved lasers.

Recent work at Osaka University's Institue of Laser Engineering in Japan suggests that ignition may be achieved at lower temperature with a second very intense laser pulse guided through a millimetre-high gold cone into the compressed fuel, and timed to coincide with the peak compression. This technique, known as 'fast ignition', means that fuel compression is separated from hot spot generation with ignition, making the process more practical.

A completely different concept, the 'Z-pinch' (or 'zeta pinch'), uses a strong electrical current in a plasma to generate X-rays, which compress a tiny D-T fuel cylinder.

Since the late 1940's, researchers have used magnetic fields to confine hot, turbulent mixtures of ions and free electrons called plasmas so they can be heated to temperatures of 100 to 300 million kelvins (180 million to 540 million degrees Fahrenheit). Under those conditions, positively charged deuterium nuclei (containing one neutron and one proton) and tritium nuclei (two neutrons and one proton) can overcome the repulsive electrostatic force that keeps them apart and "fuse" into a new, heavier helium nucleus with two neutrons and two protons. The helium nucleus has a slightly smaller mass than the sum of the masses of the two hydrogen nuclei, and the difference in mass is released as kinetic energy according to Albert Einstein's famous formula E=mc². The energy is converted to heat as the helium nucleus, also called an alpha particle, and the extra neutrons interact with the material around them.

In the 1970's, scientists began experimenting with powerful laser beams to compress and heat the hydrogen isotopes to the point of fusion, a technique called inertial confinement fusion, or ICF. In the "direct drive" approach to ICF, powerful beams of laser light are focused on a small spherical pellet containing micrograms of deuterium and tritium. The rapid heating caused by the laser "driver" makes the outer layer of the target explode. In keeping with Isaac Newton's Third Law ("For every action there is an equal and opposite reaction"), the remaining portion of the target is driven inwards in a rocket-like implosion, causing compression of the fuel inside the capsule and the formation of a shock wave, which further heats the fuel in the very center and results in a self-sustaining burn known as ignition. The fusion burn propagates outward through the cooler, outer regions of the capsule much more rapidly than the capsule can expand. Instead of magnetic fields, the plasma is confined by the inertia of its own mass – thus the term inertial confinement fusion.

Debate Round No. 1
bencbartlett

Pro

===Preface===


My opponent clearly did not read the rules of this debate. First round was acceptance only. I am keenly interested in this debate, so I’m not going to call for immediate forfeit, however, MY OPPONENT CAN NO LONGER MAKE ANY ARGUMENTS OR CLOSING STATEMENTS IN THE FINAL ROUND, as it would give him an unfair advantage. I will call for an automatic forfeit if any arguments are made in the final round. To try and preserve a coherent debate structure, I will simply shift all of Con’s turns up one round.



===Main Arguments===


C1: Magnetic confinement fusion can be self-sustaining. The main reaction used in all fusion reactors is the DT – or deuterium-tritium – reaction, expressed as D+T→He4+n+17.59MeV. [1] My opponent is incorrect in the statement that “the extra neutrons interact with the material around them.” These neutrons are in the non-thermal end of the energy spectrum (energy in the 1E7 eV range, far above the 2E-2eV thermal level), meaning that they almost always only interact with dense moderating materials after scattering for quite some time. [2] The vast majority of the neutrons exit the chamber and, in a MCF design, activate a liquid lithium “blanket”, 1) producing more tritium to use as fuel in the Li7+n→He4+T+n reaction, and 2) heating the lithium, thereby providing energy to boil water, turning a turbine, just like in a conventional nuclear or coal power plant. Alternately, water can be used instead of lithium, though the tritium-producing processes will not take place.


However, the key advantage of MCF is that it also uses the He4 byproduct to heat the plasma, as He4 retains a charge and can be redirected back into the center of the plasma with the solenoids, imparting the tremendous kinetic energy of the helium ion back into the plasma, heating it up, and eliminating the need for a constant outside energy source – something ICF does not have. This would allow the reaction to continue indefinitely with no power input other than that required to pump additional fuel into the reaction – a “self-sustaining” reaction. In contrast, by the nature of the design of inertial confinement, this cannot take place, as the helium-4 byproduct is simply waste and not utilized to further heat the plasma, making magnetic confinement far superior in this area.


C2: Magnetic confinement fusion outputs power continuously, whereas inertial confinement operates under pulses. The second main reason MCF is superior to ICF for power generation has to do with the method of power output. Magnetic confinement is by design, self-sustaining (given a point of criticality in reaction rates), and outputs power continuously, whereas ICF operates in “bursts”. One might point out that simply reloading the device quickly and refiring it may surmount this problem for power generation, but given the rather small amount of energy released in each individual “shot”, about 15 pellets would need to be expended every second. [3] Obviously, there are a few major problems with this. First, ICF, by design, requires an incredible amount of precision in geometric symmetry, as compressing the pellet unevenly in any manner will cause it to burst to one side only, preventing fusion from taking place, as a centra compression is required. To fix this problem, a hohlram, or small gold cylinder, contains the pellet. Lasers are fired at the foci of the hohlram, creating a symmetrical pattern of x-rays which diffract and compress the pellet more evenly. However, to reload an ICF reactor at rapid speeds, the replacement of the pellets and the hohlram would need to be mechanized, and the machinery to do so would interfere with these foci, destroying the symmetry of the system, and preventing the pellet from collapsing evenly, thereby precluding fusion from occurring. Furthermore, the cost could be prohibitive, as each hohlram must be remachined before each shot, as the lasers destroy both the target and the cylinder.



===Additional Remarks===


I would also like to point out that this debate involves whether or not magnetic confinement fusion is more promising as an energy source than inertial confinement fusion. My opponent has not addressed this topic at all in his argument; instead, he simply defined what magnetic and inertial confinement fusion are and explained how they work, failing to contrast their respective capabilities as a power source. Though his explanations of MCF and ICF are slightly oversimplified, I take no issue with their content. However, currently, he has not even addressed the argument.


I will reserve my rebuttal for the next round, as per the original plan. Con’s next turn will be a rebuttal, since his rounds have been shifted up one slot due to posting his initial arguments one round early.



===References===


[1] http://hyperphysics.phy-astr.gsu.edu...;


[2] http://en.wikipedia.org...


[3] https://lasers.llnl.gov...


[4] http://en.wikipedia.org...

RationalMadman

Con

There are two ways to achieve controlled nuclear fusion, by magnetic confinement and by inertial confinement. Magnetic confinement fusion uses a magnetic field to contain a hot 
plasma. Inertial confinement fusion uses an intense pulse of laser light to compress and heat a small capsule of fuel. The fuel in both cases is usually a deuterium-tritium mixture, because that combination is the easiest to fuse. Most research effort has been directed towards magnetic confinement technology. The plasma geometry is usually based on the toroidal “tokamak” configuration invented by Tamm and Sakharov in 1950 and declassified in 1957 [1]. Over 198 tokamaks have been built [2].

Four large tokamak projects were built in the 1980s. Two of these, the American TFTR [3] and the European JET [4] reactors, were aiming for breakeven fusion energy generation when first conceived, but both fell just short of this goal. Energy breakeven occurs when the energy released by the fusion reaction equals the energy put in to heat the plasma. The Japanese JT-60 tokamak [5] lacks tritium-handling facilities and is restricted to deuterium-only plasmas, but the plasma conditions it has achieved would have yielded break-even fusion output if a deuterium-tritium mix had been used [5]. The Russian T-15 tokamak [6] has explored the use of large superconducting magnets.

The ITER project has mapped out a road map to a commercial fusion power reactor, if ITER continues to demonstrate that the tokamak line of magnetic confinement is the most promising for power generation[7]

This scenario assumes that ITER will deliver on the promise of tokamak-based fusion. That isn’t guaranteed. Magnetic confinement fusion remains a scientific research problem rather than an engineering problem, and the engineering issues have barely been touched.

Sources:
[1] Plasma Physics and the Problem of Controlled Thermonuclear Reactions, I.E. Tamm and A.D. Sakharov, Proceedings of the Second International Conference on the Peaceful Uses of Atomic Energy, Vol.1, pages 1–47. Pergamon, Oxford (1961).
[2] http://www.webcitation.org...
[3] http://www.webcitation.org...
[4] http://www.webcitation.org...
[5] http://iopscience.iop.org...
[6] http://www.webcitation.org...
[7] http://www.iter.org...
Debate Round No. 2
bencbartlett

Pro

My opponent has not adressed the topic at all so far, so I am unable to post a rebuttal or response. The topic, again, is: "Magnetic confinement fusion is more promising as an energy source than inertial confinement fusion." All my opponent has done in his argument is shown that there are two main methods of inducing fusion. He has not given any indication as to why inertial confinement is superior to magnetic confinement. As such, I eagerly await his actual argument in this round. As of current, however, Con has not met the shared burden of proof, as he has not even adressed the topic. Vote Pro.
RationalMadman

Con

Magnetic confusion relies on magnets. Intertial confinement relies on electrical power only. This seems more promising.
Debate Round No. 3
bencbartlett

Pro

Unfortunately, since Con started preemptively in the first round, he is unable to introduce any new evidence in this last round. However, the only direct counterstatement to any of my contentions has been “Magnetic confusion [sic] relies on magnets. Inertial confinement relies on electrical power only. This seems more promising.” No sources have been cited, nor any reasoning for this claim provided. To be honest, I was hoping for a bit more in-depth argument, as I did preface this debate with "must be knowledgeable in the subject to accept". Also, note that the magnets used in magnetic confinement are solenoidal electromagnets, relying also only on electrical power and superconductivity. In any case, Con has not presented a complete argument to counter the original resolution, other than an uncited and unexplained opinion. Vote Pro.

RationalMadman

Con

Stupid debate anyway.
Debate Round No. 4
3 comments have been posted on this debate. Showing 1 through 3 records.
Posted by ObiWan 5 years ago
ObiWan
no problem
Posted by bencbartlett 5 years ago
bencbartlett
I'd be interested in doing that - just let me get through the first round of exams I have coming up first and then I'll challenge you.
Posted by ObiWan 5 years ago
ObiWan
This was quite disappointing really, I was hoping for a more interesting, scientific debate.

Bencbartlett, if you want to try this again, or debate a similar topic I would be happy to accept.
2 votes have been placed for this debate. Showing 1 through 2 records.
Vote Placed by ObiWan 5 years ago
ObiWan
bencbartlettRationalMadmanTied
Agreed with before the debate:--Vote Checkmark0 points
Agreed with after the debate:--Vote Checkmark0 points
Who had better conduct:Vote Checkmark--1 point
Had better spelling and grammar:--Vote Checkmark1 point
Made more convincing arguments:Vote Checkmark--3 points
Used the most reliable sources:Vote Checkmark--2 points
Total points awarded:60 
Reasons for voting decision: Pro was the only one who really addressed the topic, and by the end practically forfeited.
Vote Placed by Zaradi 5 years ago
Zaradi
bencbartlettRationalMadmanTied
Agreed with before the debate:--Vote Checkmark0 points
Agreed with after the debate:--Vote Checkmark0 points
Who had better conduct:Vote Checkmark--1 point
Had better spelling and grammar:--Vote Checkmark1 point
Made more convincing arguments:Vote Checkmark--3 points
Used the most reliable sources:Vote Checkmark--2 points
Total points awarded:60 
Reasons for voting decision: Conduct for breaching the round structure. Args since pro was the only one who's argument addressed the topic in any depth. Sources since, from the differing fonts throughout the round on con's part, I'd be willing to bet he plagiarized the first rounds.