New shape of the target

[mimboch]

Hello,
I'm trying to simulate the following shape of the jet gas target, with circular ends and a flat section in the middle .
I would be very grateful if anyone could give me a hand.
Thank you in advance.

[Status-Mirror]

Hey @mimboch,

I've adapted the basic target demo using expressions from the maths parser to obtain the following target:

which was created with this input deck:

begin:control
    nx = 800
    ny = 120
    t_end = 1.0e-15
    x_min = -20e-6
    x_max = 20e-6
    y_min = -3.0e-6
    y_max = 3.0e-6
    stdout_frequency = 100
    npart = 10 * nx * ny
end:control

begin:boundaries
    bc_x_min = open
    bc_x_max = open
    bc_y_min = open
    bc_y_max = open
end:boundaries

begin:constant
    targ_length = 25e-6
    targ_rod_thickness = 600e-9
    targ_ball_radius = 2e-6
    targ_dens = 1.0e24
end:constant

begin:species
    name = Electron
    mass = 1.0
    charge = -1.0
    frac = 0.8
    temp_ev = 1000
    
    # Rod part
    density = if (abs(y) lt 0.5*targ_rod_thickness \
                  and abs(x) lt (targ_length/2 - targ_ball_radius), \
                  targ_dens, 0)
    
    # Balls
    density = if ((abs(x)-targ_length/2 + targ_ball_radius)^2 + \
                   y^2 lt targ_ball_radius^2, targ_dens, density(Electron))
end:species

begin:species
    name = Carbon
    mass = 22033.0
    charge = 6.0
    frac = 0.2
    density = density(Electron) / 6
    temp_ev = 1000
end:species

begin:output
    dt_snapshot = t_end
    number_density = always
end:output

Hope this helps,
Stuart

[mimboch]

Thank you so much for your assistance .

[mimboch]

Hello,
I should have a smooth transition between the circles and the flat section, as shown in the attached picture. I am trying to achieve this with Expo functions, but it didn’t work.
Could you please help me again?
Thank you in advance.

[Status-Mirror]

Can you be more specific about the curve-shape? For an exponential, I would need to know where you want it to start from, which point on the circle you want it to end, and the exponential scale-length $k$, for a functional form $\exp(x/k)$.

If the older ball-rod target above doesn't work for you, then your results must be sensitive to the nature of this curve. If I just give you a random curve, it will probably have the same problem as the simple ball-rod.

[mimboch]

Hello,
Thank you for your reply; I really appreciate it.
Yes, you are absolutely right, but it is not necessarily the goal is to have these curves. For example, I could use a decreasing exponential function from 2 (center of the circle) to 5 µm on the left side and an increasing exponential function from 19 to 23 µm on the right side, with an exponential scale length k=2μm.

[mimboch]

Hello Stuart,
I succeeded in plotting the desired profile by using the following MATLAB code, but when I tried to incorporate the target density (30.n_c for 800 nm wavelength), I often return to the first shape (without curves). Could you please help me further?
` % Constants
% Rectangles
centralRectPosition = [3, -1]; % Bottom-left corner of the central rectangle
centralRectWidth = 21;
centralRectHeight = 2;

leftCirclePosition = [0, -2]; % Bottom-left corner of the left circular end
rightCirclePosition = [21, -2]; % Bottom-left corner of the right circular end
circleDiameter = 4; % Diameter of the circular ends
circleCurvature = [1, 1]; % Curvature to make it a circle

% Arcs
arcRadius = 2; % Radius for both top and bottom arcs
topArcStartPoint = [2.8; 1.8]; % Start point of the top arc
topArcEndPoint = [4.8; 1]; % End point of the top arc
bottomArcStartPoint = [4.8; -1]; % Start point of the bottom arc
bottomArcEndPoint = [2.8; -1.8]; % End point of the bottom arc

% Transformations
translationDistance = 21; % Distance to translate the left shape to the right
rotationAngle = 180; % Rotation angle in degrees
rotationPivot = [23, 0]; % Pivot point for rotation

% Visualization
xAxisLimits = [-5, 30];
yAxisLimits = [-2.5, 2.5];
shapeColor = [0, 0, 1]; % Blue color for the shapes

figure;
% Central rectangle
rectangle("Position", [centralRectPosition, centralRectWidth, centralRectHeight], ...
"FaceColor", shapeColor, "EdgeColor", "none");

hold on;
% Left circular end
rectangle("Position", [leftCirclePosition, circleDiameter, circleDiameter], ...
"FaceColor", shapeColor, "Curvature", circleCurvature, "EdgeColor", "none");

% Right circular end
rectangle("Position", [rightCirclePosition, circleDiameter, circleDiameter], ...
"FaceColor", shapeColor, "Curvature", circleCurvature, "EdgeColor", "none");

% Top and bottom arcs
[xtop, ytop] = topArc(topArcStartPoint, topArcEndPoint, arcRadius);
[xbot, ybot] = bottomArc(bottomArcStartPoint, bottomArcEndPoint, arcRadius);

% Combine arcs into a shape
x_arc = [xtop xbot];
y_arc = [ytop ybot];
left = polyshape(x_arc, y_arc);

% Transform the left shape to create the right shape
right = translate(left, translationDistance, 0); % Move to the right
right = rotate(right, rotationAngle, rotationPivot); % Rotate around the pivot

% Plot the shapes
plot(left, "FaceColor", shapeColor, "FaceAlpha", 1, "EdgeColor", "none");
plot(right, "FaceColor", shapeColor, "FaceAlpha", 1, "EdgeColor", "none");

% Visualization settings
axis equal;
xlim(xAxisLimits);
ylim(yAxisLimits);
xlabel('X (\mum)');
ylabel('Y (\mum)');
grid on;

% Functions
function [x, y] = bottomArc(startPoint, endPoint, radius)
d = norm(endPoint-startPoint);
C = (endPoint+startPoint)/2+sqrt(radius^2-d^2/4)/d*[0,-1;1,0](endPoint-startPoint);
a = atan2(startPoint(2)-C(2),startPoint(1)-C(1));
b = atan2(endPoint(2)-C(2),endPoint(1)-C(1));
b = mod(b-a,2pi)+a; % Ensure that arc moves counterclockwise
t = linspace(a,b,1000);
x = C(1)+radiuscos(t);
y = C(2)+radiussin(t);
end

function [x, y] = topArc(startPoint, endPoint, radius)
d = norm(endPoint-startPoint);
C = (endPoint+startPoint)/2+sqrt(radius^2-d^2/4)/d*[0,-1;1,0](endPoint-startPoint);
a = atan2(startPoint(2)-C(2),startPoint(1)-C(1));
b = atan2(endPoint(2)-C(2),endPoint(1)-C(1));
b = mod(b-a,2pi)+a; % Ensure that arc moves counterclockwise
t = linspace(a,b,1000);
x = C(1)+radiuscos(t);
y = C(2)+radiussin(t);
end`