US-12618709-B2 - Ion beam time of arrival (TOA) gauge

Abstract

A gauge that is configured to detect a time at which radiation enters the gauge. The gauge may include a member that is configured to transition from a first state to a second state upon receipt of the incoming radiation, and may include a light probe that is configured to detect when the member transitions to the second state. The gauge may provide for determining a time of arrival of the radiation at another gauge. For example, the gauge may correlate the time of arrival at the gauge with the another gauge, thereby providing for correlating a response time of a test specimen with actual exposure time of the test specimen to radiation (e.g., an ion beam).

Inventors

• Todd Evan Vande Brake
• Gary Lee Paderewski
• George Williams

Assignees

• ANALEX CORPORATION

Dates

Publication Date

20260505

Application Date

20240118

Claims (20)

1. 1 . A gauge comprising: a housing defining an aperture; a member configured to prevent a laser beam from traveling in a first direction beyond a location of the member when the member is in a first state, wherein the member is configured to transition from the first state to a second state in response to a radiation received by the member via the aperture, wherein when in the second state the member is configured to allow the laser beam to travel beyond the location in the first direction; and a light probe that is configured to detect when the member transitions to the second state by detecting when the laser beam travels beyond the location.
2. 2 . The gauge of claim 1 , wherein the member is configured to reflect the laser beam at the location of the member when in the first state, wherein the light probe is configured to direct the laser beam to the member in the first direction, wherein when the member is in the first state, the laser beam is reflected by the member at the location to the light probe in a second direction that is opposite the first direction, and wherein when the member is in the second state, the laser beam is not reflected by the member, such that the laser beam passes beyond the location along the first direction.
3. 3 . The gauge of claim 2 , wherein the light probe is configured to direct the laser beam along the first direction to the aperture.
4. 4 . The gauge of claim 1 , wherein the member comprises is a vaporizable portion.
5. 5 . The gauge of claim 4 , wherein the vaporizable portion comprises an aluminized coating that is configured to prevent the laser beam from traveling in the first direction beyond the location when the member is in the first state.
6. 6 . The gauge of claim 4 , wherein the vaporizable portion has a thickness anywhere from 200 nm to 355,000 nm thick along a longitudinal axis of the aperture.
7. 7 . The gauge of claim 5 , wherein the member comprises an optically transparent portion that is attached to the vaporizable portion when the member is in the first state, wherein the optically transparent portion is configured to receive the laser beam and allow the laser beam to pass through the optically transparent portion.
8. 8 . The gauge of claim 7 , wherein the optically transparent portion comprises a polymethyl methacrylate (PMMA) and the vaporizable portion coats a surface of the optically transparent portion.
9. 9 . The gauge of claim 1 , further comprising a window that is disposed between the aperture and the light probe.
10. 10 . The gauge of claim 1 , further comprising a spacer between at least a portion of the member and a radially inwardly extending shoulder of the housing.
11. 11 . The gauge of claim 10 , wherein the member comprises the spacer and a vaporizable portion that is attached to the spacer.
12. 12 . The gauge of claim 1 , further comprising a controller configured to determine a time of arrival of the radiation based on a time of the member transitioning to the second state such that the laser beam of the light probe passes beyond the location along the first direction.
13. 13 . The gauge of claim 1 , further comprising a probe adjuster configured to adjust a focus and/or a tip tilt of the light probe.
14. 14 . A test system comprising: a test cage comprising a gauge mount; the gauge of claim 1 attached to the gauge mount; and one or more phase doppler interferometry probes configured to measure a response of a test specimen to a motivating event.
15. 15 . A method of operating the gauge of claim 1 , the method comprising: directing radiation to a test specimen such that a shockwave propagates through the test specimen; and determining a time of arrival of the radiation based on the time of the member transitioning to the second state such that the laser beam of the light probe passes beyond the location along the first direction.
16. 16 . A method of determining a time of arrival of radiation, the method comprising: directing a laser beam along a first direction to a member of a gauge, such that laser beam does not travel in the first direction beyond a location of the member while the member is in a first state; directing radiation to the member such that the member transitions to a second state, whereby the laser beam passes beyond the location along the first direction; detecting, with a light probe, when the member transitions to the second state such that the laser beam travels beyond the location in the first direction; and determining a time of arrival of the radiation based on a time of the member transitioning to the second state such that the laser beam of the light probe passes beyond the location along the first direction.
17. 17 . The method of claim 16 , further comprising blocking the laser beam, with the member, such that the laser beam is prevented from traveling in the first direction beyond the location of the member while the member is in the first state.
18. 18 . The method of claim 17 , wherein the blocking step comprises reflecting the laser beam at the location of the member when the member is in the first state, wherein the light probe is configured to direct the laser beam to the member in the first direction, wherein when the member is in the first state, the laser beam is reflected by the member at the location to the light probe in a second direction that is opposite the first direction, and wherein when the member is in the second state, the laser beam is not reflected by the member, such that the laser beam passes beyond the location along the first direction.
19. 19 . The method of claim 16 , wherein transitioning the member to the second state comprises vaporizing at least a portion of the member such that the laser beam passes beyond the location along the first direction.
20. 20 . The method of claim 16 , further comprising: directing radiation to a test specimen such that a shockwave propagates through the test specimen; producing a shockwave that propagates through the test specimen based on the radiation; measuring, with a measurement device, displacement of the test specimen due to the shockwave; and determining a prompt impulse based on the displacement of the test specimen measured by the measurement device.

Description

STATEMENT OF GOVERNMENTAL INTEREST This invention was made with Government support under Contract No. N00030-20-C-0014 awarded by the United States Navy/Strategic Systems Programs. The U.S. Government has certain rights in the invention. TECHNICAL FIELD The present disclosure relates generally to measurement devices and, in particular, gauges, such as gauges for determining an exposure time of specimens exposed to radiation (e.g., ion beam radiation). BACKGROUND Test samples are exposed to ion beam radiation provided by an ion beam generator at the GAMBLE II Ion Beam Facility of the U.S. Naval Research Laboratory. Measurement tools, such as phase doppler interferometry probes, may measure a response of each test sample to the ion beam radiation. For example, the phase doppler interferometry probes may measure a prompt impulse of each test sample. Also, calorimeters may provide data to determine the fluence of the ion beam radiation, and thus the total energy received by each test sample during a test event. During the test event, there is a delay from the time at which the ion beam generator is triggered to fire and when ion beam radiation actually reaches the test specimens. Thus, an accurate timing mechanism is needed to correlate ion beam exposure time with test specimen response. SUMMARY The present application provides for a gauge that is configured to detect a time at which radiation enters the gauge. The gauge may include a member that is configured to transition from a first state to a second state upon receipt of the incoming radiation, and may include a light probe that is configured to detect when the member transitions to the second state. The gauge may provide for determining a time of arrival of the radiation at another gauge. For example, the gauge may correlate the time of arrival at the gauge with the another gauge, thereby providing for correlating a response time of a test specimen with actual exposure time of the test specimen to radiation (e.g., an ion beam). The gauge may be used at the GAMBLE II Ion Beam facility located at the U.S. Naval Research Laboratory to determine the time of arrival of the ions onto the test specimen. Previously known test assemblies are not able to accurately correlate the response time of the test specimens with the actual exposure time to ions. The gauge of the present application, on the other hand, may provide for correlating such response time with the actual exposure time. The gauge may be arranged such that the radiation arrives at the gauge at about the same time as the test specimen. For example, the gauge and the test specimen may be spaced at about the same distance from a radiation source such that the radiation reaches the gauge within 10 nanoseconds (ns) of the test specimen, or within 5 ns, 4 ns, 3 ns, 2 ns, or 1 ns. The gauge may be spaced from the radiation source a distance that within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1% of a distance that the test specimen is spaced from the radiation source. The gauge and the test specimen may be mounted to the same gauge mount of a test cage such that a plane that is orthogonal to a longitudinal axis of the test cage extends through both the gauge and the test specimen. The gauge may use a photonic displacement interferometry (PDI) to determine the ion beam time of arrival at the test specimen. For example, a laser probe may be focused through a polymethyl methacrylate (PMMA) window onto a vaporizable portion (e.g., an aluminized coating on the PMMA window). The vaporizable portion may be exposed to the ion beam through a small aperture on the TOA gauge directly in front of the vaporizable portion. The vaporizable portion may be vaporized when exposed to the ion beam, thereby causing a loss of signal from the PDI. Thus, the time of arrival of the ion beam at the specimen can be determined based on the time of the loss of signal. The gauge may comprise an aperture at its front end that is followed by the aluminized PMMA window. The gauge may comprise a spacer (e.g., an acetal spacer) followed by a PMMA safety window. The PMMA safety window may protect the PDI laser probe from any blow off or spalling from the vaporizable portion. The gauge may include a wave washer behind the safety window to take up play in the assembly stack up and account for any thickness variations in the individual components of the gauge. According to an embodiment of the present disclosure, a gauge may include a housing defining an aperture. The gauge may also include a member configured to prevent a laser beam from traveling in a first direction beyond a location of the member when the member is in a first state. The member may be configured to transition from the first state to a second state in response to a radiation received by the member via the aperture. When in the second state, the member may be configured to allow the laser beam to travel beyond the location in the first direction. The gauge may furthermore include