Traveling wave tube amplifier having a helical slow-wave structure supported by a cylindrical scaffold
Traveling-wave tube amplifiers for high-frequency signals, including terahertz signals, and methods for making a slow-wave structure for the traveling-wave tube amplifiers are provided. The slow-wave structures include helical conductors that are self-assembled via the release and relaxation of strained films from a sacrificial growth substrate.
1. A traveling wave tube amplifier comprising:
a slow-wave structure comprising:
a cylindrical scaffold comprising a dielectric film, the cylindrical scaffold having an interior surface; and
an electrically conductive helix on the interior surface of the cylindrical scaffold, the electrically conductive helix comprising a plurality of electrically conductive strips connected end-to-end;
an electron gun positioned to direct one or more beams of electrons axially through the electrically conductive helix or around the periphery of the electrically conductive helix; and
an electron collector positioned opposite the electron gun.
2. The amplifier of claim 1 , wherein the cylindrical scaffold comprises silicon nitride, silicon oxide, aluminum oxide, or diamond.
3. The amplifier of claim 1 , wherein the electrically conductive helix has an inner diameter in the range from 1 μm to 50 μm.
4. The amplifier of claim 1 , wherein each electrically conductive strip corresponds to one coil of the electrically conductive helix.
5. The amplifier of claim 1 , further comprising a dielectric support membrane, wherein the slow-wave structure is attached to the dielectric support membrane along the length of the slow-wave structure.
6. The amplifier of claim 5 , wherein the dielectric support membrane comprises diamond or silicon nitride.
7. The amplifier of claim 6 , wherein the electrically conductive helix comprises a material that can be electroplated.
8. The amplifier of claim 7 , wherein the electrically conductive helix comprises gold, copper, nickel, or silver.
9. The amplifier of claim 8 , wherein the cylindrical scaffold comprises silicon nitride, the dielectric support membrane comprises diamond, and the electrically conductive helix comprises gold.
10. The amplifier of claim 8 , wherein the electrically conductive helix has an inner diameter in the range from 1 μm to 50 μm.
11. The amplifier of claim 5 , further comprising a device substrate, wherein the portion of the dielectric support membrane to which the slow-wave structure is attached is suspended over the device substrate.
12. The amplifier of claim 1 , wherein the cylindrical scaffold comprises diamond, has a thickness in the range from 10 nm to 20 nm, and has an inside diameter in the range from 0.5 μm to 2 μm.
13. The amplifier of claim 1 , wherein the cylindrical scaffold comprises silicon nitride, has a thickness in the range from 20 nm to 40 nm, and has an inside diameter in the range from 1 μm to 5 μm.
14. The amplifier of claim 1 , wherein the cylindrical scaffold has an inside diameter in the range from 0.5 μm to 30 μm.