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Adjust MAD-NG bend face to match PTC #293

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Merged
merged 5 commits into from
May 4, 2023
Merged

Adjust MAD-NG bend face to match PTC #293

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c715d87
Change bend face to be independent of the side of the magnet.
Mar 30, 2023
33e1dfa
Merge remote-tracking branch 'upstream/dev' into fix_sbend_face
jgray-19 Apr 5, 2023
03a8971
Improve backtracking compatibility
jgray-19 Apr 5, 2023
3984811
Improve backtracking for bend_face
jgray-19 Apr 5, 2023
8381d8c
Update t to be in line with PTC and change sdir to tdir (PTC only use…
jgray-19 Apr 11, 2023
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22 changes: 12 additions & 10 deletions src/madl_dynmap.mad
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Original file line number Diff line number Diff line change
Expand Up @@ -1742,33 +1742,35 @@ function bend_face (h, m, lw) -- [NEWFACE] --

m.atdebug(h, m, lw, 'bend_face:0')

local edir, beam in m
local k0h = 0.5*h * knl[1]/(eld or el)*edir
local edir, sdir, tdir, beam in m
! h is weighted by tdir, el is weighted by sdir, so to get tdir back, we need to multiply by sdir
local k0h = 0.5*h * knl[1]/(eld or el) * sdir
local chg = beam.charge
local _beta = 1/beam.beta

for i=1,m.npar do
local x, px, y, py, t, pt, beam in m[i]
local _beta = beam and 1/beam.beta or _beta
local chg = beam and beam.charge or chg
local k0hq = k0h*chg -- k0hq must be weighted by bdir

if lw == 1 then -- to insure reversal symmetry ; horizontal wedge (only dir)
px = px + chg*k0h*x^2
if tdir == 1 then -- to insure reversal symmetry ; horizontal wedge (only tdir)
px = px + k0hq*x^2
end

local dpp = 1 + 2*pt*_beta + pt^2
local _pt2 = 1/(dpp - px^2)
local xi = 2*k0h*lw*sqrt(dpp)*_pt2
local dxi_px = 2*px*xi *_pt2
local dxi_ddel = -2 *xi*(1+pt) *_pt2
local xi = 2*k0hq*sqrt(dpp)*_pt2
local dxi_px = 2*px*xi *_pt2
local dxi_ddel = -2 *xi*(1+pt) *_pt2

x = x / (1-dxi_px*y^2)
px = px - xi*y^2
py = py - 2*xi*x*y
t = t - dxi_ddel*x*y^2
t = t + dxi_ddel*x*y^2

if lw == -1 then -- to insure reversal symmetry; horizontal wedge (only dir)
px = px - chg*k0h*x^2
if tdir == -1 then -- to insure reversal symmetry; horizontal wedge (only tdir)
px = px + k0hq*x^2
end

m[i].x = x
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