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Use of a Mylar filter to eliminate vacuum ultraviolet pulse pileup in low-energy x-ray measurements

Journal Article · · Review of Scientific Instruments
DOI:https://doi.org/10.1063/5.0101712· OSTI ID:1890157
 [1];  [2];  [2];  [3]
  1. Princeton Fusion Systems, Inc., Plainsboro, NJ (United States); Princeton Fusion Systems, Inc.
  2. Princeton Univ., NJ (United States)
  3. Princeton Fusion Systems, Inc., Plainsboro, NJ (United States)
+ Show Author Affiliations
We describe a method to reduce vacuum ultraviolet (VUV) pulse pileup (PPU) in x-ray pulse-height Silicon Drift Detector (SDD) signals. An Amptek FAST SDD, with C1 (Si3N4) window, measures bremsstrahlung emitted from PFRC-2 plasma to extract the electron temperature (Te) and density (ne). The C1 window has low transmissivity for photons with energy below 200 eV though will transmit some VUV and soft x-ray photons, which PFRC-2 plasmas abundantly emit. Multi-VUV-photon PPU contaminates the interpretation of x rays with energy > 100 eV, particularly in a low-energy exponential tail. The predicted low transmissivity of ~1 μm thick Mylar [polyethylene terephthalate (PET)] to photons of energy <100 eV led to the selection of Mylar as the candidate filter to reduce VUV PPU. Experiments were conducted on an x-ray tube with a graphite target and on a quasi-Maxwellian tenuous plasma (ne ~ 109 cm–3) with effective temperatures reaching 1500 eV. A Mylar filter thickness of 850 nm is consistent with the results. The Mylar-filter-equipped SDD was then used on the PFRC-2 plasma, showing a substantial reduction in the low-energy x-ray signal, supporting our hypothesis of the importance of VUV PPU. Here, we describe the modeling and experiments performed to characterize the effect of the Mylar filter on SDD measurements.
Research Organization:
Princeton Fusion Systems, Inc., Plainsboro, NJ (United States)
Sponsoring Organization:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
Grant/Contract Number:
AC02-09CH11466; AR0001099
OSTI ID:
1890157
Alternate ID(s):
OSTI ID: 1890515
Journal Information:
Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 9 Vol. 93; ISSN 0034-6748
Publisher:
American Institute of Physics (AIP)Copyright Statement
Country of Publication:
United States
Language:
English

References (3)

The historical development of the thermoelectrically cooled X-ray detector and its impact on the portable and hand-held XRF industries (February 2009) journal March 2010
RF Plasma Heating in the PFRC-2 Device: Motivation, Goals and Methods
  • Cohen, S.; Brunkhorst, C.; Glasser, A.
  • RADIO FREQUENCY POWER IN PLASMAS: Proceedings of the 19th Topical Conference, AIP Conference Proceedings https://doi.org/10.1063/1.3664976
conference January 2011
Using Poisson-regularized inversion of Bremsstrahlung emission to extract full electron energy distribution functions from x-ray pulse-height detector data journal February 2018

Figures / Tables (13)

FIG. 1(p. 1)figure FIG. 1
FIG. 2(p. 2)figure FIG. 2
FIG. 3(p. 2)figure FIG. 3
FIG. 4(p. 2)figure FIG. 4
FIG. 5(p. 3)figure FIG. 5
FIG. 6(p. 3)figure FIG. 6
FIG. 7(p. 3)figure FIG. 7
FIG. 10(p. 4)figure FIG. 10
FIG. 8(p. 4)figure FIG. 8
FIG. 9(p. 4)figure FIG. 9
FIG. 11(p. 5)figure FIG. 11
FIG. 12(p. 5)figure FIG. 12
FIG. 13(p. 5)figure FIG. 13

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70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Bremsstrahlung
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Vacuum ultraviolet radiation
X-ray spectroscopy