Tuesday, May 30, 2006

Mr. Beam Version 3.4.2-016

Bernd sent us the new version of MrBeam, it supports 3 different kinds of CCD camera.
a. LU 160 (wavefront sensor)
b. LU080 (beam stabilization)
c. LU160 (FROG).

Thursday, May 25, 2006

Boyer, Colgate awarded the 2006 Los Alamos Medal

Laboratory technical staff members Keith Boyer and Senior Laboratory Fellow Stirling Colgate, are recipients of the 2006 Los Alamos Medal. The Los Alamos Medal is the highest honor and most prestigious award the Laboratory can bestow upon an individual or small group. Director Bob Kuckuck will present the medals during a formal award ceremony and reception at 4 p.m. May 23, in the J. Robert Oppenheimer Study Center.

Recipients of the Los Alamos Medal are evaluated based on their exceptionally distinguished achievements that have impacted the success of the Laboratory, either through influencing mission accomplishments or enhancing distinction, making a contribution that changed the course of science and establishing a major direction for Los Alamos and/or the nation.

"Keith Boyer's and Stirling Colgate's distinguished careers at Los Alamos span more than four decades. Their contributions to Los Alamos and the nation have been immense and further underscore the vital importance this Laboratory has played in the past and the excellent science we continue to perform in support of the nation. I am honored and humbled to be able to present the 2006 Los Alamos Medal and I want to say to them, 'thank you for your contributions,' " said Director Bob Kuckuck.

Boyer has served the Laboratory for 55 years and is recognized as being the intellectual force behind Los Alamos’s entry into magnetic fusion, nuclear rocketry, laser isotope separation and inertial fusion. Boyer, who received his doctorate in nuclear physics from MIT, is credited with introducing and leading dramatic advances in science and engineering and has been involved in producing the first neutrons from a thermal plasma, co-inventing the electron beam carbon-dioxide laser and advancing x-ray lasers for high resolution microscopy. After retirement, he continued research and is responsible for a breakthrough in the development of an x-ray laser camera that promises to offer a nanoscale measurement technique comparable in importance to the development of the optical microscope. He is also recognized for his foresight in recruiting and nurturing excellent research people within the Laboratory.

“I was surprised and delighted to hear about my being awarded the Los Alamos Medal,” said Boyer. “I am particularly appreciative of the very generous support from my peers. I again feel that I am a member of Los Alamos Laboratory and have begun to think of new developments for the Laboratory.”

Colgate’s association with Los Alamos began when he was a student at the Los Alamos Ranch School until it was closed by the government in the early 1940s. He obtained his doctorate in physics from Cornell University and worked at Lawrence Livermore and New Mexico Institute of Mining and Technology. He joined the Laboratory in 1976 where he worked in the Theoretical (T) Division. He is recognized for leading the nuclear diagnostics of the nation’s largest weapons test conducted by Los Alamos, and for negotiating the cessation of high-altitude and outer space nuclear tests. Colgate also has inspired the inertial fusion and astrophysics programs at Los Alamos and Lawrence Livermore and contributed basic science to fusion ignition and burn, plasma confinement and shock wave physics. His other accomplishments include seminal work in supernovae and gamma ray bursts. Colgate is a recognized leader in recruiting leading weapons physicists and demonstrates by example that basic and applied science must be partners.

“So many people contribute to one’s career and this is especially true of a scientist,” said Colgate. “In serving two national labs and a state institution of learning I feel all those many people who have contributed to and encouraged me so much should feel associated with this honor.”

Colgate and Boyer join past Los Alamos Medal winners, Conrad Longmire, Nobel Laureate Hans Bethe, former Laboratory Director Harold Agnew, and Laboratory Fellows Nerses “Krik” Krikorian, George Cowan, Francis Harlow and Louis Rosen in this distinction.

(By Sallie Boorman)

Wednesday, May 17, 2006

Measuring the output energy

The timing delays of DG 535:

The final output energy was measured about 350 mJ with the seed pulse energy 25 mJ.

Tuesday, May 16, 2006

X-ray Anode time delay adjustment

Randy suggested firing the X-ray Cathode and Anode slightly earlier. The previous delay time was set D=B-1.31us, in this condition the Rail Gap Anode firing was missed sometimes. When the firing time was moved forward, the Rail Gap firing became stable.

The Prometheus has been passivated for about 3 hours with the hight voltage of 10kV and DG 535 time delays of B=A-1.90us, D=A-1.45us. The red light was not changed anymore.

Monday, May 15, 2006

The Prometheus Passivation

Because the output energy of the Prometheus was too low, I decided to passivate it. The chamber was vacuumed this morning, then Helium gas was filled into the chamber about 1 bar. A 16kV H.V. pulse was applied to the rail gap. After filling several mbar fluorine gas, the emission light was changed from white to red. In order to make the railgap firing at the peak time of transformer secondary, I changed the SRS DG-535 channel B timing, from B=A-1.58us to B=A-2.20us. This status has been kept for one hour, then I found a spark on the top 10k Ohm charging resistor. I had to stop passivation, and found the resistor broken. What caused this happened?

Later I replaced the broken resistor, and tried to passivate the Prometheus again. I also measure the Thyratron currents at different timing delays(158us, 190us, 220us).

Friday, May 12, 2006

Cooling the Prometheus gases, ASE too low

The Prometheus ASE was very weak, so I decided to clean the gases by cooling recycle. After cooling, the ASE became bigger, however the ASE energy dropped fast after running for several minutes. The final amplified energy of the system is only about 100 mJ. I want to passivate the Prometheus next Monday to improve the ASE output.

Thursday, May 11, 2006

Cleaning the windows

I removed the windows of the long tube, and found some small black grains on the inside surface. I carefully cleaned the window and reinstalled them immediately. After that I passivted the both tube for about one and half hours, the long and short tubes emitted red light. Finally I measured energy of the TWIN excimer with 45 mJ, and the beam pattern looked better than before.

Wednesday, May 10, 2006

TWIN dirty windows

I tried to measure the laser energy, however I found the output energy of LLG-TWIN was very low. This seed beam could not be amplified up to ~500 mJ after passing the Prometheus. The pre-amplified beam patten looked very bad, I checked the windows and found they are very dirty. So I want to clean them tomorrow.

Tuesday, May 09, 2006

Testing the Eurothrem 7100A Thyristor Controller


The Eurothrem 7100A Thyristor controller is intended to replace the Eratron SCR controller in the Prometheus laser.The Eurotherm units are speced at 100A 230/240V service with a 5 V analog control input signal.


The following circuit was breadboarded to test the Eurotherms. A Stanford Research Instrument Delay Generator is use for timing the firing of the Eurothrem and the discharging of the holding capacitor.
Rep Rate 0.2Hz
A = T+0
B = T+50ms
C = T+1.2s
D = T+1.3s
AB triggers the 900ms flip/flop gating the analog signal to the Eutotherm. CD gates the discharge transistor. The control level is adjustable form 0 to 5V. The full wave bridge output voltage is ~ 160VDC.


The oscilloscope traces shows a built in time delay of ~ 200ms between the rising edge of the control signal input and the firing of the thyristors. If the Eurothrem units are used the 200ms delay will have to figured into the system timing.
Yellow = AB Trigger monitored at F/F input
Blue = Analog Control Signal monitored at Eurotherm input
Violet = E Charge Curve monitored on the holding capacitor
Green = Discharge Signal monitored at the Discharge input
(Written by Michael F. Klawitter)

Monday, May 08, 2006

Trigger channels changed

I tried to trigger channel B (M02) of DG-535 firstly using the SDG II TRIG OUT signal and set up the other channels as below:
A=B+1.57 us
B=T+30 ns
C=B+30 ns
D=B+1.3 us
Under this setup, the laser pulse output is same as the last Friday.

Friday, May 05, 2006

The system timing adjustment

Usually we sent the SYNC OUT signal from SDG II to trigger the Prometheus, it would induce about several hundreds nanoseconds delay time. Today I changed this signal from SYNC OUT to TRIG OUT. Finally I could match the seed beam with the Prometheus ASE.

Timing setup:

SDGII: OUT1=188ns, OUT2=368ns, SYNC OUT=204ns

DG535: A=T+1.60us (Rail Gap), B=A-1.54us (M02), C=B+30ns (M01), D=A-1.31us (X-ray Anode).

Wednesday, May 03, 2006

Jitter of laser pulse

I set the Thyratron heater and reservoir voltages back to 10.06V and 8.17V. In order to avoid the acring, I inserted a plastic plate between the thyratron and ground plate.

In the afternoon, I tried to send the TWIN laser pulse to the Prometheus. Firstly I wanted to use the method of the first pulse triggered and the second pulse amplified. However, it's very difficult to match these two pulses, I thought there was a time jitter between them. The 4 channels of DG-353 were set as: A=T+250ms 212us 236ns (Rail Gap), B=A-1.66us (M02), C=B+30ns (M02), D=A-1.42us (X-ray Anode). I used a fast photo diode to measure the laser pulse and compared it with the Prometheus trigger signals. From the measurement, I found the laser pulse jitter was more than 2.0us, which might cause the failure of two pulses matching.

Then I used only one pulse to trigger the Promethus and to be amplified. The channel A of DG-535 was changed to A=T+1.71us, and the rest channels were set as above. Please notice the time division, the above is 500ns/div, this one is 100ns/div, the tracing time is same. The jitter time is less than several nanoseconds, that's enough for matching the Prometheus pulse.

However, the time delay of 1.71us was still big, the Prometheus should be triggered early a little bit (about 0.25us). Because the Thyratron (M01&M02) would be triggered early 1.66us than the Rail Gap, it means the Rail Gap delay time must be set more than 1.66us. If we want the pulses matching, the A channel should be set A=T+1.46us. I need time to consider the whole system timing.

Tuesday, May 02, 2006

The TWIN system running well

I removed the bad connector of the heater, and reconnected them. The TWIN system ran pretty good. However I found there were the arcing around the Thyratron and the ground plate, this is a small problem, I will put a plastic plate between them or tighten them.

Monday, May 01, 2006

Wire Broken

I open the TWIN chamber this afternoon, and found the wire connected to reservoir voltage was broken. I think it might cause the TWIN not running. I will repair the wire tomorrow. The filter connector was not well when we repaired the TWIN on Oct. 20, 2005.

Changing Heater and Reservoir Voltages for TWIN Thyratron

I adjusted the heater voltage and reservoir voltage. These voltages were set at 10.06 VAC(Heater) and 8.04 VAC (Reservoir) respectively. In the beginning, I turn on the system after 10 or 15 minutes warming up, the TWIN ran at 5 Hz for 1 second, then the repetition rate changed to 1 Hz, after 2 or 3 shoots, there was no operation anymore. I increased the V_H to 10.71 VAC, V_R to 8.35 VAC the TWIN did not run. When I increased the V_R up to 8.77 VAC, the TWIN was interlocked as soon as I turn on.

I have to shut down the TWIN system. Several minutes later, I turn on the system and warmed up, set the V_H 11.38 VAC, V_R 8.40 VAC, the repetition rate 5Hz. This time the TWIN ran normally, then I increased the repetition rate to 6Hz, everything was ok! Then turn off the system, set the repetition rate up to 8 Hz, the TWIN was not running, after a few seconds, it ran at low rate then up to 8 Hz. After the system ran for a couple minutes, I turn it off again and increased the repetition rate up to 10Hz, this time the TWIN ran normally after 1 minute. However, when I decreased the rate down to 5 Hz, the TWIN was dead again.

I have to shut down the TWIN again and left it not run for a couple of minutes. Then I set up the V_H 11.35VAC, V_R 8.35VAC, the TWIN has been run well for about 30 minutes. Then the TWIN excimer became unstable, there were one miss fire after 10 shoots (@repetition rate 10Hz). I switched off the TWIN and waited for several minutes, then turn it on, but just run 1 minutes, the TWIN became unstable either at 5Hz or 10Hz.

I found the TWIN excimer was sensitive to the reservoir voltages, when V_R under 8.35 VAC, the TWIN could be run; when the reservoir value up to 8.35 VAC, the power supply would be interlocked. I don't know why.