Difference between revisions of "Grad pulse.m"

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         rho  - spin system state vector
 
         rho  - spin system state vector
 
+
 
           L  - system Liouvillian
 
           L  - system Liouvillian
 
+
 
       g_amp  - gradient amplitude, Gauss/cm
 
       g_amp  - gradient amplitude, Gauss/cm
 
+
 
       s_len  - sample length, cm
 
       s_len  - sample length, cm
 
+
 
       g_dur  - gradient pulse duration, seconds
 
       g_dur  - gradient pulse duration, seconds
 
+
 
       s_fac  - gradient shape factor, use 1 for
 
       s_fac  - gradient shape factor, use 1 for
 
                 square gradient pulses
 
                 square gradient pulses
Line 37: Line 37:
  
  
''Version 2.2, authors: [[Ilya Kuprov]]''
+
''Version 2.2, authors: [[Luke Edwards]], [[Ilya Kuprov]]''

Revision as of 11:32, 14 August 2018

Emulates the effect of a gradient pulse on the sample average density matrix using Edwards formalism. It is assumed that the effect of diffusion is negligible, that the gradient is linear, and that it is antisymmetric about the middle of the sample.

Syntax

    rho=grad_pulse(spin_system,rho,g_amp,s_len,g_dur,s_fac)

Arguments

        rho   - spin system state vector

          L   - system Liouvillian

      g_amp   - gradient amplitude, Gauss/cm

      s_len   - sample length, cm

      g_dur   - gradient pulse duration, seconds

      s_fac   - gradient shape factor, use 1 for
                square gradient pulses

Outputs

     rho - spin system state vector, integrated over
           the spatial coordinate

Examples

See examples/fundamentals/gradient_test_1.m file for an example of using this function.

Notes

  1. The function integrates over sample coordinates - subsequent gradient pulses would not refocus the magnetization that it has defocused. To simulate a gradient sandwich, use grad_sandw.m function. More information on the subject is available in Luke's paper (http://dx.doi.org/10.1016/j.jmr.2014.01.011).
  2. This function is OK for standalone crusher gradients; for more sophisticated gradient work, use the imaging context.

See also

grad_sandw.m, imaging.m


Version 2.2, authors: Luke Edwards, Ilya Kuprov