Electron beam generation apparatus and electron beam generation method

An electron beam generation method for generating an electron beam by propagating pulsed laser light in a supersonic gas flow, the electron beam generation method comprising:

• a first step of generating the supersonic gas flow flowing along a first direction under a vacuum atmosphere by a supersonic nozzle;
• a second step of inserting a knife edge into the supersonic gas flow from one side in a second direction intersecting the first direction and forming a shock wave in the supersonic gas flow;
• and
• a third step of radiating the pulsed laser light into the supersonic gas flow by a radiation unit, propagating the pulsed laser light to pass through the shock wave in the supersonic gas flow, and generating the electron beam,
• wherein the supersonic nozzle includes
• a convergence portion having a downstream end forming a throat and an upstream end having a flow channel cross-sectional area larger than a cross-sectional area of the throat, and
• a flow straightening chamber configured to be smoothly connected to the upstream end of the convergence portion and extend by a predetermined length, and
• wherein, in the first step, a gas is caused to flow by the predetermined length in the flow straightening chamber, and then the gas converges while being caused to flow in the convergence portion.