I am trying to create the yellow gradient of the beam.
So, far I have unsuccessfully tried it as
So, I am thinking whether this can be achieved through gradient or blend.
Also note that the gradient in your source image will look different in CMYK than in RGB. If you intend to print the design, this won't matter. But deep indigo & fuchsia tones are more drab in CMYK. So if you are having trouble recreating the exact colors in the yellow gradient, this may be good to know.
You can change which color space you work in via File > Document Color Mode.