Question about fusion

  • Thread starter FEBAUSA
  • Start date
Question about fusion....

What are the problems for development, continuouly power production and economical, in a nuclear fusion reactor and nuclear fusion power plant ?
 

ohwilleke

Gold Member
1,425
350
It takes more energy to create and sustain the reaction than it produces. One of the most common approaches used magenetic fields to contain the reaction, but that takes more energy than the reaction generates, for example,
 

Morbius

Science Advisor
Dearly Missed
1,125
5
FEBAUSA said:
What are the problems for development, continuouly power production and economical, in a nuclear fusion reactor and nuclear fusion power plant ?
FEBAUSA,

In a word - "breakeven".

As of yet, we don't know how to achieve "breakeven" - that is to get as
much energy out of the plasma as we put in to make the plasma.

The basic approaches to fusion are "magnetic confinement" and
"inertial confinement".

Magnetic confinement uses machines like "tokamaks" to confine the
plasma with magnetic fields. The problem there is that a magnetically
confined plasma has all sorts of instabilities - and it breaks up before
we can hold it long enough to get back as much energy as we put into it.
Magnetic confinement is chiefly studied at the Princeton Plasma Physics
Laboratory:

http://www.pppl.gov/

The other approach is "inertial confinement" fusion. Here, you don't
even attempt to try to "hold" the plasma. You create a very dense
plasma that burns very fast, and you count on the fact that the inertia
of the mass of the plasma will hold it together long enough to get
useful energy. The confinement time will be very short - but if the
fusion burn is fast enough - you could still get a useful amount of energy.
[ After all, that's how hydrogen bombs work - they don't hold together
very long - but they produce energy so fast that the small confinement
time is long enough ].

The problem with inertial confinement fusion is that we haven't been
able to create a plasma large enough to trap the alpha particles which
you want to do to get "ignition". That is, just as a fire uses the heat from
combustion to keep the fire going - you want to trap the alpha particles
to keep the fusion fire going. Previous experimental machines couldn't
do that - but that is changing.

The principal means of heating and compressing a plasma in inertial
confinement fusion is with lasers - also called "laser fusion". The
principal research centers are at Lawrence Livermore National Lab,
and the Laboratory for Laser Energetics at the University of Rochester.

Lawrence Livermore National Laboratory is building the NIF - the
National Ignition Facility. This 192 beam laser should be powerful
enough to create a plasma large enough to achieve ignition. The NIF
building is finished, as are the first set of lasers. More lasers will be
brought online during the next few years until the entire 192 beam
complement of lasers is finished. See:

National Ignition Facility at Lawrence Livermore National Laboratory:

http://www.llnl.gov/nif/
http://www.llnl.gov/nif/project/index.html
http://www.llnl.gov/nif/project/news_nel1.html

OMEGA laser at the Laboratory for Laser Energetics at University of Rochester:
http://www.lle.rochester.edu/

Another method for inertial confinement is to use large pulsed power
sources to "magnetically implode" plasmas in what is called "Z-pinch
inertial confinement fusion". This research is underway at the
Sandia National Laboratory in Albuquerque, New Mexico:

http://www.sandia.gov/pulsedpower/
http://www.sandia.gov/LabNews/LN09-24-99/fusion_story.html
http://zpinch.sandia.gov/ [Broken]
http://www.sandia.gov/media/z290.htm
http://zpinch.sandia.gov/Z/Images/z.jpg [Broken]

Hope that's enough to get you started.

Dr. Gregory Greenman
Physicist
 
Last edited by a moderator:
2,193
2
Nice post Morbius! I always enjoy reading your comments.
 

Morbius

Science Advisor
Dearly Missed
1,125
5
pallidin said:
Nice post Morbius! I always enjoy reading your comments.
pallidin,

Thank You

Dr. Gregory Greenman
Physicist
 

enigma

Staff Emeritus
Science Advisor
Gold Member
1,738
9
Antiphon's question has been split into it's own thread
 
What are projects about nuclear controlled fusion reactor to achieve Q > 1, or possibly obtain Q > 1.
 

Astronuc

Staff Emeritus
Science Advisor
18,551
1,674
Fusion is my favorite topic to discuss and read. I just found out from a friend today that undergraduates can take classes dealing with fusion, they used to only be graduate level. I looked around and found that Dr. Weston "Bill" Stacey, a former director of Argonne's fusion program, could be my professor!

Has anyone heard of the text that is used: W. M. Stacey, Fusion Plasma Analysis, 1st Edition, Krieger, 1981?
 

Astronuc

Staff Emeritus
Science Advisor
18,551
1,674
theCandyman said:
Fusion is my favorite topic to discuss and read. I just found out from a friend today that undergraduates can take classes dealing with fusion, they used to only be graduate level. I looked around and found that Dr. Weston "Bill" Stacey, a former director of Argonne's fusion program, could be my professor!

Has anyone heard of the text that is used: W. M. Stacey, Fusion Plasma Analysis, 1st Edition, Krieger, 1981?
Yeah, I have that book and used parts of it when I taught Fusion Engineering almost 20 years ago. I also used Dolan, but it's a set of three, which are hard to find, and I misplaced or lost Parts 2 and 3.
 
Last edited:
Hi Morbius.

I have a question that I think you are very capable of answering.

Do you think that by using an array of LASERs that we could literially paint a high energy image or Photosphere shell like the sun has, but as a miniature version or virtual duplicate of a miniature star with shell and core structures?

Do you think cloning a stars exact exterior and interior structure would be an effective means to copy the exact process within the star itself? .ie Holographic Sun created by LASER interference.

Thanks. :smile:
 

Morbius

Science Advisor
Dearly Missed
1,125
5
OnTheCuttingEdge2006 said:
Hi Morbius.

I have a question that I think you are very capable of answering.

Do you think that by using an array of LASERs that we could literially paint a high energy image or Photosphere shell like the sun has, but as a miniature version or virtual duplicate of a miniature star with shell and core structures?

Do you think cloning a stars exact exterior and interior structure would be an effective means to copy the exact process within the star itself? .ie Holographic Sun created by LASER interference.

Thanks. :smile:
In a word: NO.

You aren't going to be able to "paint" or "copy" a miniature version of the Sun.

For one thing; even if you did - it wouldn't stay the way you copied it.

Suppose you made a ball of high temperature, high density plasma similar to what one
finds in the interior of the Sun. It wouldn't stay that way - it would explode.

The Sun is like a great big exploding Hydrogen Bomb. However, this Hydrogen Bomb
is so massive that its gravity opposes the explosion and keeps the Sun stable.

Without all that mass - and the consequent gravity - there's nothing to hold your plasma
intact - so it would just explode.

In a way, the fusion targets at Livermore are like these little exploding Suns.
However, they won't have a photosphere. You get a photosphere when the distances
that the photons of light travel are much, much less than the diameter of the object.

Clearly, our little exploding suns are much too small to have photospheres.

We can't just copy the ways stars do things - we have to do things that make sense on
Earth - with the quantities of mass that we have available.

Dr. Gregory Greenman
Physicist
 
Last edited:

Related Threads for: Question about fusion

Replies
17
Views
3K
Replies
31
Views
7K
  • Posted
2
Replies
28
Views
7K
Replies
23
Views
7K

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving
Top