The high negative bias of a sample in a scanning electron microscope constitutes the “cathode lens” with a strong electric field just above the sample surface. This mode offers a convenient tool for controlling the landing energy of electrons down to units or even fractions of electronvolts with only slight readjustments of the column. Moreover, the field accelerates and collimates the signal e...

A high power cross-field amplifier is under develop ment at SLAC with the objective of providing sufficient peak power to feed a section of an X-Band (11.424 GHz) accelerator without the need for pulse compression. The CFA being designed employs a conventional distributed secondary emission cathode but a novel anode structure which consists of an array of vane resonators alternatively coupled t...

It is shown that non-prepoled PLZT ceramics, both in ferroelectric and antiferroelectric phase, emit intense current bursts when a negative exciting voltage is applied to the rear surface of the cathode. The spontaneous polarization induced in the bulk by applying the field through the cathode disk, creates a sheet of negative charge on the diode boundary of the ferroelectric. This, in turn, in...

Diamond-based thermionic emission devices could provide a means to produce clean and renewable energy through direct heat-to-electrical energy conversion. Hindering progress of the technology are the thermionic output current and threshold temperature of the emitter cathode. In this report, we study the effects on thermionic emission caused by in situ exposure of the diamond cathode to beta rad...

Core-shell TiO(2)/C and TiC/C nanofibers are fabricated in situ on Ti and Al ion-implanted Ti substrates by a thermochemical reaction in acetone and the growth mechanism is described. Implantation of Al into Ti leads to in situ growth of TiC/C in lieu of TiO(2)/C nanofibers. This is because Al has a higher affinity to oxygen than Ti and Ti reacts preferentially with C to form TiC. The Ti foil s...

Initial operation of a 17 GHz RF photocathode electron gun has been achieved at MIT. This is the first photocathode electron gun to operate at a frequency above 2.856 GHz. Such electron guns have the potential for achieving record high values of electron beam quality. The 1.5 cell, p-mode, copper cavity was tested with 5-10 MW, 100 ns, 17.145 GHz pulses from a klystron amplifier built by Haimso...

A 140 GHz high power gyrotron has recently been operated in a 14 T Bitter magnet to characterize emission as a function of magnetic field and beam current. The velocity ratio (or pitch angle) a = (v±.)/(v1 ) of the beam electrons is a critical parameter for high efficiency gyrotron operation and was measured using a capacitive probe located in the beam tunnel before the cavity. The observed vel...

Dark current emitted from the surface of high-field RF cavities can contribute to radiation levels and cryo budget and can cause damage to sensitive accelerator components such as the photocathode. The superconducting niobium cavities in the booster module of bERLinPro will have surface fields strong enough to produce significant dark current from field emission, so simulations were made using ...

The light extraction of OLED has been successfully enhanced by the combination of multi-cathode structure and high refractive index intermediate layer, which are introduced to control the surface plasmon coupling in the metal cathode and the distribution of optical energy in OLED, respectively. From the multi scale optical analysis, it was found that an approximately 70% of electromagnetic ener...