A high-power magnetron assembly comprising: a high-power magnetron comprising: a cathode having a hollow cylinder form, and configured to emit electrons in response to receiving a supply of voltage from a power supply, and an anode concentrically surrounding the cathode and configured to attract the emitted electrons across an interaction region between the cathode and the anode; and a compact magnetic field generator (101, 201, 601) configured to generate a specified magnetic field within the magnetron, the compact magnetic field generator comprising: a plurality of permanent magnets including: a central cylindrical, rod shaped cathode magnet (105, 405, 605) having a longitudinal axis of symmetry and arranged within the cathode, wherein the cathode magnet is annularly surrounded by the cathode; and an anode magnet (130, 430) annularly surrounding an outer perimeter of the anode; wherein an arrangement of the plurality of permanent magnets concentrically about the longitudinal axis of symmetry is configured to form the specified magnetic field within the interaction region that bounds the electrons emitted within the interaction region; and wherein the anode magnet has a length along the longitudinal axis of symmetry, which length is marginally longer than that of the interaction region, whereby the anode magnet is configured to generate a majority of a magnetic flux within the interaction region. a high-power magnetron comprising: a cathode having a hollow cylinder form, and configured to emit electrons in response to receiving a supply of voltage from a power supply, and an anode concentrically surrounding the cathode and configured to attract the emitted electrons across an interaction region between the cathode and the anode; and a cathode having a hollow cylinder form, and configured to emit electrons in response to receiving a supply of voltage from a power supply, and an anode concentrically surrounding the cathode and configured to attract the emitted electrons across an interaction region between the cathode and the anode; and a compact magnetic field generator (101, 201, 601) configured to generate a specified magnetic field within the magnetron, the compact magnetic field generator comprising: a plurality of permanent magnets including: a central cylindrical, rod shaped cathode magnet (105, 405, 605) having a longitudinal axis of symmetry and arranged within the cathode, wherein the cathode magnet is annularly surrounded by the cathode; and an anode magnet (130, 430) annularly surrounding an outer perimeter of the anode; wherein an arrangement of the plurality of permanent magnets concentrically about the longitudinal axis of symmetry is configured to form the specified magnetic field within the interaction region that bounds the electrons emitted within the interaction region; and wherein the anode magnet has a length along the longitudinal axis of symmetry, which length is marginally longer than that of the interaction region, whereby the anode magnet is configured to generate a majority of a magnetic flux within the interaction region. a plurality of permanent magnets including: a central cylindrical, rod shaped cathode magnet (105, 405, 605) having a longitudinal axis of symmetry and arranged within the cathode, wherein the cathode magnet is annularly surrounded by the cathode; and an anode magnet (130, 430) annularly surrounding an outer perimeter of the anode; a central cylindrical, rod shaped cathode magnet (105, 405, 605) having a longitudinal axis of symmetry and arranged within the cathode, wherein the cathode magnet is annularly surrounded by the cathode; and an anode magnet (130, 430) annularly surrounding an outer perimeter of the anode; wherein an arrangement of the plurality of permanent magnets concentrically about the longitudinal axis of symmetry is configured to form the specified magnetic field within the interaction region that bounds the electrons emitted within the interaction region; and wherein the anode magnet has a length along the longitudinal axis of symmetry, which length is marginally longer than that of the interaction region, whereby the anode magnet is configured to generate a majority of a magnetic flux within the interaction region.