We show recent progress of a high efficiency 100 kW IOT amplifier design operating at 1.3 GHz. The IOT is composed of a multi cavity interaction circuit with upward of 80% power efficiency. We present details of the electrical and thermal design of the IOT as well as testing plans.

We show results of 3D space-charge beam dynamics simulation of an L-Band inductive output tube (IOT) rf electron gun. These results are essential to optimize the interaction circuit potentially achieving 100 kW of average power with upward of 80% power efficiency.

L3 Electron Devices has developed a high-power multibeam inductive output tube (MBIOT) for the European Spallation Source. In July 2014, L3 was awarded a contract for the design, manufacture, and test of a 1.2 MW, 704.42 MHz, pulsed power MBIOT. In October 2016, factory acceptance testing of the L6200 1.2-MW MBIOT was completed at L3 Electron Devices. In October 2017, site acceptance testing was successfully completed at the European Organization for Nuclear Research (CERN). The ten-beam, permanent magnet-focused device meets the maximum 1.2-MW output power specification with a dc-to-RF efficiency of 70%; efficiency is maintained above 60% down to 650 kW. Factory testing at L3 was limited to a cathode voltage of 43.6 kV and a maximum pulse width of 200 mu s. The CERN MBIOT test stand enabled operation at the preferred cathode voltage of 45 kV and at the full pulsewidth of 4 ms. The CERN test stand also offered the ability to individually adjust the filament voltage and bias voltage to each gun, which was not possible with the L3 test configuration. The CERN test stand and MBIOT are currently being prepared to demonstrate long-duration operation.

L-3 Electron Devices has successfully completed factory testing of the L6200 1.2 MW Multi-Beam Inductive Output Tube (MBIOT) for the European Spallation Source. The ten-beam, permanent magnet-focused device meets the maximum 1.2 MW output power specification at 704.42 MHz with a DC-to-RF efficiency of 68.4%; efficiency is maintained above 60% down to 650 kW. The gain at 1.2 MW exceeds 21 dB. No oscillations were detected at any point during operation. The MBIOT is currently being prepared for shipment, after which it will undergo long-duration life testing.

L-3 Communications Electron Devices (L-3 EDD) is developing a high power Multi-beam IOT (MBIOT) for the European Spallation Source (ESS). Extensive simulation work has been completed and, where possible, results were validated against experiment using a scaled single-beam prototype. The MBIOT design has been finalized; fabrication of the tube is in progress, and configuration of a factory test bay is underway.

L-3 Communications Electron Devices (L-3 EDD) has provided Inductive Output Tubes (IOTs) for the UHF television broadcast industry since 1998. More recently, we have produced a variety of high power versions specifically for accelerator applications, e.g., the 90 kW 500 MHz L-4444 for the NSLS-II at Brookhaven National Laboratory. L-3 EDD is now leveraging this expertise to develop a new super-power IOT for the European Spallation Source.

This paper will review the evolution of high power UHF vacuum electronics that supports the needs of the TV broadcast community. From the early days of analog, and the advent of digital broadcast, high power VEDs have played an important role in providing free over the air TV.

L-3 Communications, Electron Devices Division (EDD) has developed an inductive output tube (IOT) with large instantaneous bandwidth for radar and communications applications. As in conventional IOTs, this wideband IOT (WBIOT) provides high efficiency, good linearity, and compact size through emission-gated modulation of the electron beam at the cathode surface. Increases in gain, bandwidth, and duty factor will be discussed through test results and simulation.

Modeling of emission-gated electron guns used on inductive output tubes (IOTs) will be presented. The simulations are performed with the time-domain module of the NRL / SAIC electron gun and collector code MICHELLE, with RF electric and magnetic fields imported from the HFSS electromagnetic solver.

Inductive output tubes (IOTs) employ emission gating to modulate the electron beam directly at the cathode surface. The high efficiency of these compact devices has motivated their use in UHF television broadcast and particle accelerators. The instantaneous bandwidth of broadcast IOTs is two percent (6 MHz). Many radar and communications applications - in which the linearity and efficiency of the IOT are highly desirable - require a significantly larger bandwidth. L-3 Electron Devices Division (EDD) is therefore developing a wideband IOT (WBIOT) which will provide output power levels suitable for UHF radar with a 1 dB bandwidth greater than ten percent.