Proposed arrangement consists of large evacuated chamber containing smaller Dewar chamber into which liquid neon is introduced. Zeolite crystal is mounted in wall of chamber, with one side in contact with neon and other exposed to evacuated chamber. Electron gun is used to bombard crystal

Grunthaner, F. J.

English

NASA Technical Reports Server

October 1975	 B75-10239 
NASA TECH BRIEF 
NASA Pasadena Office 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Soft X-Ray Lasers Using Distributed-Feedback Reflection: A Concept 
It has not been possible to construct an X-ray laser 
because no known mirror will reflect X-rays and 
produce a reinforced coherent beam. It has now been 
proposed that an X-ray laser could be made using 
distributed feedback instead of mirrors for reflection 
and coherent reinforcement. The channels in 
molecular-sieve crystals (e.g., zeolites) could be filled 
with a gas such as neon which would be excited to 
emit photons. Bragg scattering of the photons by 
periodic lattice planes in the zeolite would reflect and 
reinforce the photons, and channels in the crystals 
would serve as waveguides. 
Zeolites are aluminosilicate crystals with porous 
structures with one-, two-, or three-dimensional 
channels having diameters of from 3 to 12 X. Neon 
gas at very low pressures could be introduced into the 
channels. Electron bombardment of the gas could 
form Ne+. This would cause K-shell fluorescence and 
produce photons in the soft X-ray region. The photons 
would be scattered at the periodically-located lattice 
planes in the crystals. 
Excited 0--i" '--	 - 
Species O-M.	 Feedback Wave p	 X-Ray Wave 
......... 
Periodic Lattice Unit 
Figure 1. Distributed-Feedback Reflection
The wavelength of the neon Ka emission is at 14.6 
A, and a zeolite with channel periodicity one-half that 
would produce scattering at each site which would be 
in phase with scattering at all the other sites. Because 
of the higher index of refraction within the channel, it 
should act as a waveguide to produce a coherent 
beam. Figure 1 is a diagram of how distributed 
reflection would occur in a zeolite channel. 
A proposed arrangement for an X-ray laser is 
shown in Figure 2. A large evacuated chamber 
contains a smaller Dewar chamber into which liquid 
neon is introduced. A zeolite crystal is mounted in the 
wall of the chamber, with one side in contact with the 
liquid neon and the other exposed to the evacuated 
chamber. An electron gun, aimed by electromagnetic 
deflection, is used to bombard the zeolite crystal. 
A detector (with a beryllium shield to stop scattered 
electrons) is used to aline the electron optics to get the 
maximum channeling. Before the neon is introduced, 
the Faraday cup is moved to get the best electron path 
as measured by the detector. 
Liquid neon is then allowed to diffuse through the 
crystal channels, and the crystal is bombarded with 
electrons. This should generate a plasma in the gas 
mixture (neon with selected amounts of helium 
impurity admitted) leading to an inversion of ionized 
states in the neon. The helium provides He+ for the 
neutralization of space-charge buildup. 
The lasing action could be adjusted by varying the 
power of the electron-beam gun and varying the 
temperature of the crystal. It is anticipated that neon 
Ka line widths on the order of 1 to 10 meV will be 
obtained.
(continued overleaf) 
This document was prepared under the sponsorship of the National	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States 	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19750000239 2020-03-19T20:29:15+00:00Z
Crystal 
Neon 
Cell 
I	 I	 Berryllium
çri hrWindow
 L Detector J
Movable 
Train
Electromagnet'\
Faraday 
!• J	 Cup 
L 
Electron-Beam Gun 
Electron Path
	 -.
-i-Ill
J	 4	 [ 
Vacuum Pump
Figure 2. Proposed Configuration of X-Ray Laser 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Reference: TSP75-10239
Patent status: 
This invention is owned by NASA, and a patent 
application has been filed. Inquiries concerning 
nonexclusive or exclusive license for its commercial 
development should be addressed to: 
Patent Counsel 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Source: Frank J. Grunthaner of 
Caltech/JPL 
(NPO-13532) 
B75-10239	 Category: 03 (Physical Sciences) 


Soft X-ray lasers using distributed-feedback reflection: A concept

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server