Can we short JFET source and gate junctions as shown in the circuit?
Yes, the drain current is the same as the source current and there is no gate current except for a very low level of leakage.

The bottom of Rs should be connected to circuit common (ground).

The drain supply should be a voltage, not a current source.

With an ideal current source the current will always be 7.5mA regardless of the value of Rx or anything else.


More here: https://forum.allaboutcircuits.com/threads/can-we-short-jfet-source-and-gate-junctions-as-shown-in-the-circuit.175900/