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FieldTmp: new solver larmor #68

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merged 3 commits into from
Oct 10, 2013

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ax3l
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@ax3l ax3l commented Sep 25, 2013

Adds a new solver to FieldTmp to calculate the local emitted (relativistic) larmor energy.

- missing math::pow prevents compile so far
@ghost ghost assigned PrometheusPi Sep 25, 2013
const float_X el_factor = charge * charge
/ ( 6.0 * PI * EPS0 *
math::pow(SPEED_OF_LIGHT, 5) * mass * mass );
const float_X energyLarmor = el_factor * math::pow(gamma, 4)
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In the original Lamor equation, gamma^6 is used. Your approach optimzes this by using momentum instead of speed.
However:
beta(t_i) = momentum(t_i) / ( mass * SPEED_OF_LIGHT * gamma(t_i) )
Is the time dependence of gamma in the vector part considered in your derivation?
I am not sure, if we can consider gamma to be constant between two consecutive time steps.

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I personally belief this is not a problem since we are already including an first order error when deriving our acceleration.
Just need to check it.

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All right, that's a good point.

@ax3l
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ax3l commented Sep 25, 2013

Note: still discussing the gamma(t) vs gamma(t-1) problem.

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After discussing this issue with @ax3l we decided to merge this even if we have the following problems:

  • strong acceleration cases rapid rise of gamma, which might cause
    numerical problems with the implemented equation
  • therefore, one has to be careful with strong E fields (B-fields do not change gamma)
  • macro particles are point like (which might be not a good approximation)
  • we are uncertain about the numerical accuracy of the equation used

But other than that, this looks like an excellent tool to determine the origin of the radiation.
Great job @ax3l !!!

let's merge!

PrometheusPi added a commit that referenced this pull request Oct 10, 2013
FieldTmp: new solver larmor
@PrometheusPi PrometheusPi merged commit 04dedf9 into ComputationalRadiationPhysics:dev Oct 10, 2013
@ax3l ax3l deleted the topic/larmor branch October 10, 2013 14:39
ax3l pushed a commit to ax3l/picongpu that referenced this pull request Feb 17, 2015
…x-coinstraints_checker_no_instance

The constraints check is no longer instantiated
psychocoderHPC pushed a commit to psychocoderHPC/picongpu that referenced this pull request Nov 1, 2017
1cc899e Merge pull request ComputationalRadiationPhysics#72 from ComputationalRadiationPhysics/doc-installTBB
f77cbbc Docs: Install TBB
0c523c1 Merge pull request ComputationalRadiationPhysics#69 from psychocoderHPC/topic-tbbSupport
09b45d1 add TBB support
41cc5c7 Merge pull request ComputationalRadiationPhysics#70 from psychocoderHPC/topic-updateAlpaka
8732079 update alpaka to latest dev
a76e409 Merge pull request ComputationalRadiationPhysics#71 from psychocoderHPC/topic-updateTravisModules
3872172 increase cmake minimal version
8967663 update travis modules boost/cmake
fbd0b8e Merge pull request ComputationalRadiationPhysics#68 from psychocoderHPC/fix-cuda9DefaultConstructorWarnings
164ace2 fix warning: CUDA 9

git-subtree-dir: thirdParty/cupla
git-subtree-split: 1cc899ed11a2c7e454a80deb1a2e8e0b06f091d9
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2 participants