optimal control under fixed gradient field

[Mengjia He]

Dear Prof. Kuprov,

I'm considering running the optimal control under a given gradient field, i.e., applying RF and gradient pulse simultaneously.

In this case, the gradient pulse is known but shaped. To include the gradient in optimal control, I guess it's difficult to contribute the gradient to a drift ensemble because I can only define the Hamiltonian as time-invariant.

Another way is to define the gradient in control. operators, accompanying frozen gradient waveform. I'm not sure if it's possible, but I'd like to modify the ensemble.m to hold my task

do you have any suggestions?

Thank you,
Mengjia

[kuprov]

Actually - it will work just fine: Spinach optimal control module does support time-dependent drifts. Pile up all voxels into blocks of a block-diagonal matrix, stack up all voxel state vectors to match, and simply specify a cell array of drifts instead of a single drift. One per time point of your pulse.

You will need the developer version for that, I think - follow the SVN instructions on the download page.