Plasma lens effects in elegant (quadrupole)

[eadli]

Dear all,

We are trying to integrate a simple plasma lens effect into our elegant simulation. The model we want to implement is quadrupole focusing, in both planes simultaneously. Our beams may have energy spread of order delta = +/- 50%, so the energy dependence of the focusing must be taken into account to all order.

I.e. if we could define a QUAD with the same sign in both planes our problem would be solved.

Since this does not seem to be possible, we tried to use the LTHINLENS element where focal lengths can be set individually. However, the focal-lengths seem not to be energy-dependent, therefore we cannot use this element either.

Finally, we have looked at the general EMATRIX element, but found no way to include energy-dependence to all orders.

Does anyone have a tip for how to either
a) create an element equivalent to a quadrupole with focusing in both planes?
b) alternatively, is there an element which allows for manipulating the beam in a more general way; not only 1st and 2nd order matrices, but rather x_i = f(..x_j..) ? (Such an element would be very useful for other purposes as well, I believe).

Best regards, Erik Adli
SLAC National Accelerator Laboratory

[michael_borland]

Erik,

The best (i.e., only) way to do this right now is using the SCRIPT element. Basically, it allows you to write an external program or script that is integrated into elegant as an element of the beamline.

Having a built-in option for a lens like this is a good idea. I'll try to work it into the next release.

--Michael

[eadli]

Dear Michael,

Thank you for the quick reply. Yes, it would be awesome and I believe useful for a number of people to have a lens element. An upright quadrupole with the option to set the same focusing for x and y would do the job as a simple lens.

Best regards, Erik