Low-energy electron beam generation in inductively coupled plasma via a DC biased grid

Low-energy electron beam generation using a DC biased grid was investigated in an inductively coupled plasma (ICP). The electron beam was measured in argon gas at various pressures, ICP source powers, and substrate voltages (Vsub). At a low ICP source power (50 W), an electron beam was generated even at small values of Vsub (10 V), however at a high ICP source power (200 W), an electron beam was only generated when a higher voltage (30 V) was applied due to the short sheath thickness on the grid surface. The sheath on the grid surface is an important factor for generating electron beams because low-energy electrons are blocked. If the sheath thickness to small, a high voltage should be applied to generate an electron beam, as accelerate regions cannot exist without the sheath. At high pressure, since electrons experience numerous neutral collisions, a high substrate voltage is needed to generate an electron beam. However, if the applied substrate voltage becomes too high (40 V) at high pressure, high-energy electrons result in secondary plasma under the grid. Therefore, maintaining a low pressure and low ICP source power is important for generating electron beams.

Adaptation of energy methods to automated calculation of mobile machines frame constructions

The paper shows that the adaptation of energy methods to automated calculation of mobile machines frame constructions consists of developing a single algorithm applicable to different construction schemes. The calculation outset still remains the idea of getting a function of potential energy of deformation as a function with unknown inner power factors. Search for local function minimum of potential power of deformation has been based on the function’s discrete grid-surface. We managed to reach tactical flexibility of coordinate descent method in an attempt to continue approaching local minimum in cases of a dead end situation by changing the discrete course. The paper suggests extending the implemented algorithm from 3-D surface dealing only with two power factors, to n-D one with many unknown values.

Atmospheric plasma jet device for versatile electron microscope grid treatment

Atmospheric pressure plasmas have been widely applied in surface modification and biomedical treatment due to its ability to generate highly reactive radicals and charged particles. In cryogenic electron microscopy (cryo-EM), plasmas have been used in eliminating the surface contaminants as well as generating the hydrophilic surface to embed the specimen on grids. Particularly, plasma treatment is a prerequisite for negative stain and quantifoil grids,which are coated with hydrophobic carbon on the grid surface. Here we introduce a nonthermal atmospheric plasma jet system as an alternative new tool for surface treatment. Unlike the conventional glow discharger, we found that the plasma jet system successfully cleans the grid surface and introduces hydrophilicity on grids in the ambient environment without introducing a vacuum. Therefore, we anticipate the plasma jet system will be beneficial in many aspects, such as cost-effective, convenient, versatile, and potential applications in surface modification for both negative stain and cryo-EM grid treatment.

Generation of Electron and Fast Atom Beams by a Grid Immersed in Plasma

We present a new method of product processing with beams of accelerated electrons and fast neutral atoms, which are generated by an immersed in plasma grid under a high negative voltage of 5 kV. The electrons appear due to secondary emission from the grid surface provoked by its bombardment with ions accelerated from the plasma. At the gas pressure not exceeding 0.1 Pa the ions with energy of 5 keV reach the grid without collisions in the space charge sheaths near its surface and their current in the grid circuit is by 2-3 times lower than the electron current. At higher pressures accelerated ions due to charge exchange collisions in the sheaths turn into fast neutral atoms leaving the sheaths and forming the beams. With the pressure increasing, the electron beam current diminishes and the current of fast atom beam grows.

Time-resolved cryoEM using Spotiton

We present an approach for preparing cryoEM grids to study short-lived molecular states. Using piezo electric dispensing, two independent streams of ~50 pL sample drops are deposited within 10 ms of each other onto a nanowire EM grid surface, and the mixing reaction stops when the grid is vitrified in liquid ethane, on the order of ~100 ms later. We demonstrate the utility of this approach for four biological systems where short-lived states are of high interest.

Atmospheric Pressure Plasma Processing of an Optical Sinusoidal Grid

Sinusoidal grid with nanometric precision is adopted as a surface encoder to measure multiple degree-of-freedom motions. This paper proposes the atmospheric pressure plasma processing (APPP) technique to fabricate an optical sinusoidal grid surface. The characteristics of removal function and surface generation mechanism are firstly presented. Both simulation and experiment validate the effectiveness of APPP to fabricate a sinusoidal grid surface with nanometric precision. Post mechanical polishing experiments show that APPP features can be well maintained while the surface roughness is greatly reduced to meet the optical requirement.