Optimization of neon soft X-ray emission from 200 J plasma focus device for application in soft X-ray lithography

Abstract

The Fast Miniature Plasma Focus (FMPF) device is basically made up of coaxial electrodes with centrally placed anode and six cathode rods surrounding them concentrically. They are enclosed in a vacuum chamber, filled with low pressure operating gas. However, in our experiments, these cathode rods were removed to investigate the influence of them on neon soft X-ray (SXR) and hard X-ray (HXR) emission from the device. On removal of cathode rods, the cathode base plate serves as cathode and the plasma sheath is formed between the anode and the base plate of cathode. Neon was used as the operating gas for our experiments and the FMPF device used is of 235 J energy capacities. The experimental results showed that the FMPF device was able to focus better and the SXR emission efficiency was five times higher without cathode rods than with cathode rods. On the contrary, HXR emission did not vary with and without cathode rods. This observed phenomenon was further cross-checked through imaging of plasma dynamics, with and without cathode rods. FMPF device consists of 4 Pseudo Spark Gap (PSG) switches, which need to operate synchronously to deliver high voltage from capacitors to the anode. It was also seen that, the presence or absence of cathode rods also influence the synchronous operation of PSG switches. It also implies that this is one definite way to optimize the SXR emission from the FMPF device. This study reveals an important finding that, cathode rods play a vital role in the formation of plasma sheath with consequential influence on the radiation emission from plasma focus devices. Enhancement of the X-ray emission from this device is definitely a stepping stone in the realization of this device for industrial applications such as X-ray lithography for semiconductor industries.

Dense plasma focus: different cathode geometries and their influence on the hard x-ray production

“…Plasma focus devices [1][2][3][4][5] are devices with the capacity of, by the demand of the operator, producing pulses of hard x-ray (several hundred of keV), nuclear fusion neutrons, energetic electrons and ions, plasma jets and other radiations. These interesting characteristics have been and can be applied to different fields, like modification and evaluation of materials [6][7][8][9][10][11][12], preventive analysis of fault [13], detection of nuclides [14], medical applications [15,16], soil humidity measurements [17], nanofabrication of semiconductors [18], to radiograph of biological and inorganic samples [19], lithography [20][21][22][23][24][25] between others. This type of z-pinch are self-scaled [26,27] then, from mJ to MJ, it can be used a set of scale rules to design one.…”

“…Kalaiselvi et al [21] evaluates the behavior of a plasma focus with and without a cathode filling the discharge chamber with neon gas. They do not register any change in the maximum hard x-ray production.…”

Experimental Study of Hard X-Ray Parameters in Plasma Focus Devices

“…Рентгеновское излучение камер ПФ условно можно разделить на мягкое рентгеновское излучение (МРИ) с энергией квантов 1-10 кэВ и жёсткое рентгеновское излучение (ЖРИ) с энергией квантов, доходящей до сотен кэВ. МРИ связывают с объёмным излучением высокотемпературной плазмы пинча в камере ПФ, и ему посвящено достаточно много исследований в рамках рентгенографии, рентгеновской литографии и других применений [12,13].…”

X-ray lithography of SU8 photoresist using fast miniature plasma focus device and its characterization using FTIR spectroscopy

“…This phenomenon is very helpful to monitor the extent of cross linking of the photoresist due to various lithographic parameters [25,26]. The thin films of SU8 on Si wafer were prepared in a class 1000 cleanroom environment facility at LiMiNT beamline of Singapore Synchrotron Light Source (SSLS) [27].…”