walk into unscientific

be honest.

In fact, from the very beginning, Xu Yun knew that Yang Shiju was by no means a strong-willed person.

After all, in the original history.

Although he once shouted, "There is no way the mainland can shoot down the U2 I drive," this sounded like a morale booster for his own side.

But in fact it is.

He has never dared to fly to the mainland even once in his life. At most, he only flew half a circle to Xiangjiang and Kinmen.

Yang Shiju even wrote this kind of pure oral pleasure in his memoirs, which shows how bad this person's character is.

Therefore, Xu Yun was not surprised that he chose to confess to Lin Anbang.

But what he didn't expect was that Yang Shiju would be so cowardly.
After confirming the identity of 'Li Nanping' pretended by Xu Yun.

He was afraid that the information he provided would overlap with that of Li Nanping, which would reduce Lin Anbang's patience and the money he received, so he started to lose money like he had eaten Wallace.

In the end, he even found out that Bruce Johnson, the then Strategic Air Command commander, liked to find long-legged Taiwanese girls. Xu Yun was very suspicious of whether the water Lin Anbang gave him contained veritaserum.
At the end.

Xu Yun even came up with a guess:
It turned out that Yang Shiju's expression was actually an act. He was ready to react before he saw Li Nanping, and his fierce expression was just to wait for a price.
Of course.

For comrades like Lin Anbang on the secrecy front, this is obviously a good thing.

After all, these days, due to the blockage of the strait and signal problems, it is very difficult to transmit messages between the other side and the mainland.

Otherwise, Xie Hanguang’s tragic story would not have appeared later.

The Air Force to which Yang Shiju belongs is the weakest link in the already weak intelligence system.

Because the profession of pilot requires long-term training, the time span is very long, and basically belongs to the direct lineage of a certain force, so it is difficult to insert a nail.

Therefore, a lot of the information provided by Yang Shiju is indeed of considerable value.

If Yang Shiju fell into the hands of those across the sea, he might actually be able to survive relying on this information - after all, after World War II, they even accepted a certain unit starting with the number seven.

However, rabbits and eagles are born with different values. Yang Shiju's hands were stained with too much blood, and his evil deeds were countless.

Therefore, this kind of person is destined to have only one ending:
The final judgment was carried out amidst the rebuke of the people.

As for how Yang Shiju will scold Xu Yun and Lin Anbang after learning the truth, that is beyond Xu Yun's control.

He's almost dead anyway, why don't you want him to curse a few words?
this afternoon.

After regaining consciousness, Yang Shiju was taken away from the base through secret channels and was sent to an unknown location.

But what is basically certain is that.

After he finishes explaining what he needs to explain, he will probably use his own black blood to apologize to the innocent people in this land who he has harmed.

Xu Yun and Lin Yu quickly put Yang Shiju's matter behind them and refocused their minds on their own affairs.

in the next days.

The entire 221 base continues to move forward at its original pace.

Xu Yun's daily job is to run around in various project teams and do some seemingly ordinary tasks.

But as the saying goes, tall buildings rise from the ground.

No matter how great a construction project is, it is still built with ordinary bricks.

When these small tasks add up day after day, they will inevitably lead to bigger things.
Qualitative change!

A month later.

221 base.

In the basement where the theory team is located.

Today.

In this basement, almost all members of the theoretical department and base leaders of the base are gathered:

Li Jue, Lao Guo, Cheng Kaijia, Lu Guangda, Wang Ganchang, Chen Nengkuan, Da Da, Huang Zuqia
Even the big guys like Qian Bingqiong, Qian Wushi, and Zhao Zhongyao also appeared here.

These two types of people are also clearly divided into two parts from their seats:
The base leaders sat near the back, somewhat similar to the teachers who would sit in on public classes in later generations.

Many members of the theoretical group sat relatively close to the front. Four or five people shared a table with a thick stack of calculation papers placed on the table.

And it's different from usual.

In this basement today, the expressions on everyone's faces are extremely subtle:
There is tension,

There is excitement,

serious,

There are also expectations
Even Xu Yun, a time traveler from later generations, looked the same at this time.

After about 2 minutes or so.

Dengdengdeng-

Lu Guangda stood up from the first row, walked quickly to the front of the room, and stopped beside a blackboard.

He looked around, took a deep breath, and said slowly:
"Comrades, before we get down to business, I would like to ask a question first."

"Does any of the comrades here remember how long it has been since our theoretical organization was established?"

Hear this.

A girl in the audience with short hair and a bit buck teeth but looked very energetic raised her hand:
"Director Lu, I remember, today is the 1074th day."

"Yes. It's been 1074 days."

Lu Guangda's eyes showed a hint of reminiscence and emotion, and he said:
"It's been 1074 days. Not to mention the difficulties in life, our theory team has been very tired in the daily studio."

"In the early days, computers had insufficient computing power, so we could only use abacus and pen calculations to solve differential equations. It would take six people an entire night to calculate a formula."

"Later, when we broke through the earliest theoretical barriers, we encountered the dilemma of having no Chinese materials. We could only translate word by word by burning coal lamps."

talking.

Lu Guangda pointed to the wall on the right again and said:

"The first comrades who came to our research group should all know that the layout of our basement was divided into two rooms on the left and right."

"The one on the right is larger and was originally the earliest office location."

"The area of ​​the room we are in now is relatively small, only about one-third of the room next door. The previous plan was to store used calculation papers."

"As we calculated the results, we suddenly discovered that the original room could no longer hold the manuscript paper.

"So I had no choice but to switch the office location and the utility room - I took a look before the meeting and there wasn't much space in that big room to put paper."

Hearing what Lu Guangda said.

The corners of Xu Yun's mouth moved in the audience, but in the end he remained silent.

Although he had learned about these things in Yu Min's interview in later generations, he had already read the content.

But after Lu Guangda said the same words, his emotions still had some uncontrollable ups and downs.

The area of ​​the room they were in was about one hundred square meters, and the height was only a little over two and a half meters because it was located underground. ,
According to Lu Guangda.

The area of ​​the room next door is three times that of this one, and such a large room is filled with manuscript papers.
This is a picture that makes people speechless just thinking about it, and it is nothing more than the painstaking efforts.

This is actually only a small part.

According to the situation mentioned in Mr. Yu Min’s later interviews.

A few years later, the 221 base moved from Jinyintan to the Ninth Hospital of Sichuan Province. As time goes by, there are more than a dozen trucks of manuscript paper.
"call"

thought here.

Xu Yun could only breathe out a breath of inexplicable emotion.

And next to the blackboard.

Lu Guangda made the opposite move to Xu Yun.

His chest bulged, he took a deep breath, and his voice suddenly rose a bit:

"But comrades, our efforts are not in vain. While the space in the next door room is being squeezed, the space we have opened up is getting bigger and bigger."

"From the earliest potential barrier calculations, followed by the derivation of anomaly coefficients, and then the measurement of free radical concentration and neutron transport equations"

"There are 15 steps in the chain reaction, and as of today, only the last one remains!"

Speaking of the end.

Lu Guangda even excitedly waved his hand and grabbed it in the air, as if he had grasped it.
The throat of fate!
That's right.

It is the 1074th day since the establishment of the theoretical group, and it is also the 107th morning of Xu Yun's time travel.

The atomic bomb. That is, the [Yuqing] sub-theoretical part of the Taishang project has finally reached the end of the derivation process.
The last level!
Well known.

After the uranium-235 nucleus absorbs a neutron, the composite nucleus is in an excited state and oscillates.

Oscillation results in two situations:
One is that the composite nucleus is reduced from an ellipsoid to a spherical shape, and then emits gamma rays (prompt gamma rays) to release excess energy;

The other, due to its greater excitation energy, rapidly splits the composite nucleus into two independent nuclei.

The neutrons emitted during the fission of atomic nuclei are called fission neutrons.

Then the uranium nucleus is bombarded with neutrons, and as a result, the nucleus splits into two medium-mass fission fragments, releasing a large amount of energy and 2 to 3 fast neutrons at the same time.

under appropriate conditions.

These neutrons will be absorbed by other uranium nuclei, causing fission.

Like a chain, they are interlocked and passed down from generation to generation, forming a self-sustaining chain reaction.

This is the essence of nuclear weapons theory, and everything starts from this principle.

In September three years ago.

The Ninth Institute established a theoretical department, and Lu Guangda served as the director of the theoretical department, thus starting the theoretical research on chain reactions.

Since three years ago.

Lu Guangda and the theoretical designers conducted theoretical work preparations for two full years.

After obtaining a large amount of data on explosion mechanics, neutron transmission, nuclear reactions and material properties under high temperature and pressure, the exploratory pre-research phase was completed at the beginning of this year.

Starting from February this year, they officially entered a new stage:
How to extend the chain reaction to applications, that is, the design of atomic bombs.

According to the original historical trajectory.

Lu Guangda and the others will officially complete the theoretical design between the end of February and early March next year, and then officially begin to shift their focus to parts production and experimentation.

But now with Xu Yun's appearance, this time has been pushed forward by nearly five months.

Even though five months seems like a short time, for rabbits, it is a life-saving time!
Then Lu Guangda quickly glanced at Xu Yun, adjusted his breathing rate, and continued:

"Of course, the last hurdle we face is not easy. It can even be said to be the most difficult problem in the theoretical part."

"That is, the calculation of the thickness of the detonation wave reaction zone."

As mentioned earlier, atomic bombs can be divided into two types from a structural point of view.

One is the squeeze type, also known as the "gun type".

This type of atomic bomb uses a "barrel" device to separate two pieces of fissile material smaller than the critical mass.

When chemical explosives explode.

Under the high pressure generated, they quickly close together and reach a supercritical state, triggering a nuclear explosion.The second type is the implosion type.

Its principle is to use ordinary high explosives to make a spherical device.

A nuclear charge of less than the critical mass—that is, uranium-235 or plutonium-239—is then pelletized and placed in the center of the explosive pellet.

Finally, the electric detonator is ignited synchronously, and all points of the explosive ball detonate at the same time, generating a centripetally focused compression wave.

The compression wave will instantly and violently compress the nuclear charge sphere, increase its density, make it supercritical, and realize a self-sustaining chain reaction to cause a nuclear explosion.

Compared with the compressed atomic bomb, the structural advantage of the implosion type is obviously higher.

However, implosion-type atomic bombs will suffer from poor fission and significantly reduced power if they are compressed unevenly.

Therefore, when designing, the parameters of the thickness of the detonation wave reaction zone must be taken into consideration.

The essence of detonation is violent combustion at supersonic speed, so this part of the situation actually has a corresponding physical model, called ZND.

This is the classic theory of explosive detonation, established by Zelidovich and von Neumann in the 40s.

Only by constructing a suitable ZND model can the theoretical design of the atomic bomb be completed.

The rabbits didn't even grasp the punctuation points of all the information in this part, which shows how difficult it is to derive.

but
Now that we have reached this point, how can we retreat?
Lu Guangda looked around the scene again. Without any more nonsense, he directly started assigning topics:
"Comrade Taiping!"

A middle-aged man in his 30s quickly stood up on the chair diagonally opposite Xu Yun:
"To!"

"Your group is responsible for deriving the precursor core concentration parameters!"

"understand!"

"Comrade Wang Aifang!"

As soon as he finished speaking, another lesbian stood up. This person had an ordinary appearance and dark complexion, but her eyes were very bright:
"To!"

"You and Comrades Huang Wendong, Anyang, and Xu Zhiyuan are responsible for calculating the boundaries of laminar flames!"

"Yes!"

"Comrade Chen Hansheng"

As Lu Guangda announced his name one by one, members of the theoretical team took over their respective tasks one after another.

None of these tasks are easy.

For example, pioneer nuclear concentration.

The precursor nuclear concentration is actually the precursor nuclear concentration of later generations, which involves the generation time of fission neutrons:
The neutrons released during nuclear fission are collectively called fission neutrons. Fission neutrons can be divided into two situations according to their emission time.

The first is that the stimulated complex nucleus splits into two nuclear fragments, each fragment having an excess of neutrons and the excess energy required to emit one neutron from a stability perspective.

This excited unstable nuclear fragment often emits one or several neutrons within a very short time after its formation. These neutrons are called prompt neutrons.

其他的核裂变碎片如87Br及137I等经过贝塔-衰变后分别转化为87Kr和137Xe， 87Kr和137Xe形成后立即衰变并放出中子。

Neutrons like these emitted by 87Kr and 137Xe will be emitted for quite some time after nuclear fission, so they are called slow neutrons.

The time difference between the two is one generation time, and the dispersion peak concentration of prompt neutrons is the precursor core concentration.

The simulation process of this scenario involves a lot of calculations, and it is one of the most difficult aspects even in the derivation of the entire nuclear fission ZND model.

Fortunately, Xu Yun has been doing a lot of work for the theoretical team in the past period, and with their own capabilities, they should have a chance to break through this problem.

1 minute later.

Lu Guangda, who was thinking about the task arrangement, paused slightly and his tone became a little more serious:
"Comrade Xu Yun!"

Hearing his name, Xu Yun immediately sat up straight:
"To!"

Lu Guangda raised his head and looked at him, nodded slightly and said:

"You are in a group with Comrade Yu Min, Comrade Chen Nengkuan, Comrade Cai Shaohui, Comrade Chen Jingrun, Comrade Feng Kang and Comrade Hua Luogeng. Comrade Chen Nengkuan is the team leader and is responsible for the waveform calculation of the explosive lens!"

Swah——

The voice just fell.

Many people at the scene looked at Xu Yun.

If we talk about the derivation of precursor nuclear concentration, it is the most difficult link in the derivation of the nuclear fission ZND model, probably in the top three or five ranges.

Then the waveform calculation of the explosive lens is undoubtedly the most difficult point in the entire process - the most difficult one.

Seeing everyone's gazes on him, Xu Yun couldn't help but feel a little stirred in his heart.

These eyes are pressure, but also expectations.

But Xu Yun did not feel panic.

Isn't it just the waveform calculation of the explosive lens?

Isn't this just fine?
There seemed to be stars twinkling in his eyes, and rivers and seas surging in his chest. Xu Yun's energy sank into his dantian, and he waved his hand with great confidence and pride:

"Greater than! Fix it!"

10 minute later.

Each group after the tasks were assigned began to calculate the data they needed to derive on the spot.

The number of people in Xu Yun's group was larger than that of other groups, and they were assigned a larger rectangular table.

"A few comrades."

After seated.

Among them, Chen Nengkuan, who was second only to Hua Luogeng in age, coughed lightly and said:
"According to the design plan of the atomic bomb, the ignition neutron source device should be designed before the explosive lens."

"However, this module does not belong to the category of chain reaction - it is considered an application field, so the relevant technical research is mainly solved by the comrades from the Second Branch Factory."

"So the main thing we need to consider this time is the explosive lens itself, that is, the calculation of the explosion cross section and the waveform of the detonation wave."

Hearing Chen Nengkuan's words.

Several people at the scene nodded subconsciously.

Chen Nengkuan is currently the leader of the experimental group of the light nuclear group. He is responsible for the study of material properties under high temperature and pressure. He is considered a senior expert in explosive lenses.

Although his popularity is not as high as that of Lu Guangda, he is still one of the two bombs and one satellite, which shows his strong ability.

Seeing that everyone was very cooperative with his words, Chen Nengkuan continued to take out a piece of paper and quickly wrote down a formula:
"This is the critical equation for a spherical nuclear bomb with a reflective layer derived by our light nuclear group. It gives the relationship between the physical properties of various materials and their radii when the core with a reflective layer is critical."

"Based on this equation, it is assumed that a set of explosive lenses detonates the main explosive column to generate a centripetal detonation wave, pushing the neutron reflection layer to rapidly compress the uranium-235 fuel ball."

"When the reflective layer and the nuclear fuel are tightly combined, the delay circuit activates the neutron tube to release neutrons to ignite the nuclear fuel in the supercritical state, thereby triggering a chain reaction."

"What we need to calculate now is the specific thickness of the neutron reflection layer and the limit value of u - the latter is actually a certain expression of the waveform."

"Now let's discuss the first point first. Do you have any specific ideas?"

Hear this.

Hua Luogeng, Chen Jingrun and Feng Kang all looked at each other and fell into silence.

After all, they are responsible for computing power support. Such physical and theoretical matters are not their responsibility. Speaking easily will affect the discussion.

Among the remaining people, Xu Yun thought for a while and took the lead in saying:

"Director Chen, I have an idea."

"How about we look at the neutron reflection layer, that is, the maximum acceleration that the flying board can achieve after being driven by explosives and the acceleration time, and then calculate it with the conservation of neutron flux?"

Anyone who was a classmate of Oppenheimer in his previous life should know this.

The critical mass changes according to the shape, and nuclear fission is related to the critical volume and critical mass.

If the volume is not large enough or the mass is not enough, the neutrons will escape before they hit the nucleus.

Relative to the flight of neutrons, the distance between atomic nuclei is very large.

Without enough volume and weight, few neutrons can hit the nucleus.

Neutrons must have a sufficient probability of hitting atomic nuclei in order to produce more neutrons to hit more nuclei to create a chain reaction.

If it takes a long time for one of them to hit, the neutrons produced will most likely fly out, and nuclear fission will not occur at all.

As for ways to increase this probability?
Naturally, it is necessary to add a "shield" outside so that the flying neutrons can be reflected back and hit again.

This is somewhat similar to the cover of a pinball game, which is the neutron reflective layer.

Well known.

铀裂变反应方程式235U+1n=137Ba+97Kr+2n，也就是一个中子和铀-235反应生成137Ba， 97Kr和两个中子。

This is also the source of the energy of the atomic bomb explosion.

At the same time.

On the boundary surface between the nuclear fuel and the reflector, there must be a basic theorem that the neutron flux and the neutron leakage are equal.

That's right!

See here.

Presumably some smart students have already realized this.

The nonlinear neutron transport equation deduced by Xu Yun and Lu Guangda and the others was able to describe the boundary conditions of this scenario.

That is:
∫zJ =uhsΣSφD(r,t)+λs/3=limr→04πDA(rL+1)er/L=SA=S4πD.

At the same time, according to Chen Nengkuan, they have derived the critical equation of a spherical nuclear bomb with a reflective layer.

After the two are combined with each other, a smooth hyperboloid structure can be obtained.

Then we solve the analytical solution for this structure, and the answer is the thickness of the neutron reflection layer in the subcritical state.

By the way.

This was also the big pit where Heisenberg overturned.

At that time, Heisenberg's boundary conditions used the absorption boundary commonly used in physical models, but this thing should actually be calculated using the reflection boundary.

This is also the key to Xu Yun being able to propose a solution based on theory rather than tools in the entire development of nuclear weapons. After all, it involves neutrons, which somewhat overlaps with his original major.

"Is the neutron flux conserved?"

Both Da Yu and Chen Nengkuan are top tycoons in related fields. After Xu Yun proposed this concept, their eyes suddenly lit up.

Good idea!

Seeing that Da Da didn't even say hello, he quickly picked up his pen and started calculating.

"The temperatures of electrons and ions are the same, so the bremsstrahlung power density can be directly applied here, which is the Betty-Heitler formula."

“单个中子的平均能量公式是ε=3/2kBT，已知的主炸药的外径为78.5cm，爆轰波从主炸药外端传播至反射层共耗时t=S/U=2.39X10-5秒.”

"Then their impact speed is about 3KM/s, which can be put into the neutron transport equation and then combined."

After a while.

Da Da suddenly clapped his hands:

"Calculated, the specific thickness of the neutron reflection layer is 4.554 centimeters!"

Note:
I'll post a side story tomorrow, but I'm still short of word count.