LASER MICROFABRICATION OF THZ WAKEFIELD STRUCTURES
- Euclid Techlabs LLC, Cleveland, OH (United States)
Purpose of the research: X-Ray free electron lasers are unique tools for investigating nanoscale structure and dynamics. These are large facilities because they require electrons to be accelerated to few GeV energies. To make them compact, an acceleration at high gradient and high frequency is proposed. However at this moment, there is no reliable fabrication method for high frequency (>100GHz) accelerating structures. Due to small wavelength accelerating structures at high frequency require microfabrication techniques with incredible shape error control (sub-micron). In this case, feature dimensions required lie between the state of the art CNC machining and semiconductor etching technologies. Description of the research: The ultimate goal of the project is to fabricate mm-wave wakefield structure using laser ablation. The waveguide will be produced in a split block: two copper plates with corrugated half-channel ablated in them will be joined together to form the required corrugated waveguide. A combination of laser beam rastering, stage translation and inline metrology allows for precise fabrication of long corrugated waveguides. In recent years, laser micromachining has made impressive improvements in terms of accuracy, scalability and surface finish. Furthermore, the availability of femtosecond lasers yields ablation without melting. Surfaces processed in this fashion exhibit less structural damage and are expected to have a high damage threshold. Results of the research: In Phase I, we produced several waveguide prototypes. We produced a long, 5 cm planar corrugated structure and performed extensive metrology characterization and determined that we were able to hold 3% tolerance on depth (sub-micron absolute value) and 1% tolerance on feature periodicity (2 microns on 200um). We also developed an approach of inside-tube ablation for enclosed cylinder corrugation, however overall outlook for corrugated cylinder fabrication is not promising due to extreme energy densities on off-axis paraboloid mirrors and the need to remove ablated debris. In conclusion: laser ablation was shown to be a promising technology for planar THz geometries. Potential applications: The proposed approach allows the fabrication of intricate corrugated structures for microwave components in the mm and sub-mm range. Currently such structures are fabricated in multiple steps based on semiconductor technologies that include lithography, etching and sputtering. This process is expensive and structures are limited in their size and breakdown strength. Laser microfabrication paired with online metrology is an inexpensive alternative, a perfect approach for rapid prototyping of high power THz structures for vacuum electronics and wakefield acceleration
- Research Organization:
- Euclid Techlabs LLC, Cleveland, OH (United States)
- Sponsoring Organization:
- USDOE
- Contributing Organization:
- UCLA Pegasus Laboratory
- DOE Contract Number:
- SC0019646
- OSTI ID:
- 1630825
- Type / Phase:
- SBIR (Phase I)
- Report Number(s):
- DOE - Euclid Techlabs - PH1 - 19646; 19646
- Country of Publication:
- United States
- Language:
- English
Similar Records
Deep-etch silicon millimeter waveguide structure for electron acceleration
Application of Plasma Waveguides to High Energy Accelerators