Methods and devices for producing an electron beam

An electron gun, comprising:

• a paraelectric cathode including:
• a paraelectric layer, of paraelectric material, having a proximal face and a distal face, said paraelectric layer sandwiched between:
• on said proximal face, a back electrode;
• and
• on said distal face, a front electrode including at least one hole,
• said hole providing fluid communication between said distal face of said paraelectric layer and a volume distal to said front electrode,
• the electron gun further comprising an electrical power supply, functionally associated with said back electrode and with said front electrode, said electrical power supply configured to:
• provide a back electrode rest potential to said back electrode and a front electrode rest potential to said front electrode of not less than −500V different from an anode;
• and
• on activation, to provide an excitation potential pulse to at least one of said front electrode and said back electrode, said excitation pulse sufficient to increases the absolute value of the potential difference between said front electrode and said back electrode by not less than 300 V at a rate not slower than 6 V/nanosecond.

A method of producing an electron beam, comprising:

• a. providing an electron gun, comprising:
• a paraelectric cathode including:
• a paraelectric layer, of paraelectric material, having a proximal face and a distal face, said paraelectric layer sandwiched between:
• on said proximal face, a back electrode;
• and
• on said distal face, a front electrode including at least one hole,
• said hole providing fluid communication between said distal face of said paraelectric layer and a volume distal to said front electrode;
• b. during a rest period, maintaining said back electrode at a back electrode rest potential and said front electrode at a front electrode rest potential, both said rest potentials not less than −500 V different from an anode potential, wherein an electrode rest potential difference value is not greater than 200 V;
• c. applying at least one excitation potential pulse having a duration not greater than 2.5 microsecond to said paraelectric cathode, wherein:
• i. during said application of said excitation potential pulse, increasing the absolute value of the potential difference between said front electrode and said back electrode to not less than 300 V greater than said electrode rest potential difference value at a rate not slower than 6 V/nanosecond, thereby generating plasma in said at least one hole of said front electrode,
• ii. subsequent to ‘i’, maintaining said generated plasma in said at least one hole for a period of not less than 50 nanoseconds, and
• iii. subsequent to ‘ii’, extinguishing said plasma by reducing the value of the potential difference between said front electrode and said back electrode;
• and
• d. during ‘c’, extracting electrons from said generated plasma towards said anode as a beam of electrons.