Pulsed Supersonic Beams from High Pressure Source: Simulation Results and Experimental Measurements

Abstract

Pulsed beams, originating from a high pressure, fast acting valve equipped with a shaped nozzle, can now be generated at high repetition rates and with moderate vacuum pumping speeds. The high intensity beams are discussed, together with the skimmer requirements that must be met in order to propagate the skimmed beams in a high-vacuum environment without significant disruption of the beam or substantial increases in beam temperature.

Investigation of the on-axis atom number density in the supersonic gas jet under high gas backing pressure by simulation

“…However, as stated in Ref. 9, the boundary layer thickness under high gas pressure is less than tens of micrometers. Hence its effects on the lateral expansion can be neglected under a gas backing pressure of several tens of bars.…”

“…Thus one a Author to whom correspondence should be addressed: kimd@postech.ac.kr 2158-3226/2015/5(10)/107220/7 5, 107220-1 © Author(s) 2015 expects the cluster size deviation when the scaling law is used to estimate the cluster size under a high gas backing pressure. Up to now, there have existed many papers about the investigation of the gas jet and its cluster size, [9][10][11][12][13][14][15][16][17][18][19] and there have been papers reporting the cluster size deviation from the size expected by the scaling laws 20,21 and some works concerned about the understanding of the deviation. 22 In Ref.…”

Improved spatial separation of neutral molecules

“…9,45 These beams have internal temperatures below 1 K, but in order to avoid beam heating, they require large, multi-millimeter diameter skimmers and correspondingly large mechanical apertures for the deflector. Furthermore, strong electric fields and field gradients allow for strong deflection and separation.…”

The radial dimension of a supersonic jet expansion from conical nozzle

“…3,4 The production of a gas jet and its characterization have attracted interests and been extensively studied. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] Usually, a supersonic clustered gas jet can be produced by the adiabatic expansion of gas under a high backing pressure through a conical nozzle into vacuum. The dimension of a gas jet is an important parameter for the determination of interaction length.…”

“…Unfortunately, due to the lateral gas expansion into vacuum, the diameter of a gas jet will be larger than the idealized one. 8,21,22 Thus it is important to know how the lateral gas expansion makes effects on the radial dimension of a supersonic gas jet. In this work, a large number of simulations about supersonic gas jet in case of a conical nozzle with a throat diameter of 0.5 mm were made using the Boldarev's 2D model.…”